EP2886629B1 - Process for the hydrodesulfuration of hydrocarbon fractions - Google Patents

Process for the hydrodesulfuration of hydrocarbon fractions Download PDF

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Publication number
EP2886629B1
EP2886629B1 EP14306951.6A EP14306951A EP2886629B1 EP 2886629 B1 EP2886629 B1 EP 2886629B1 EP 14306951 A EP14306951 A EP 14306951A EP 2886629 B1 EP2886629 B1 EP 2886629B1
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Prior art keywords
stage
metal
weight
hydrocarbons
cut
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German (de)
French (fr)
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EP2886629A1 (en
Inventor
Julien Gornay
Philibert Leflaive
Olivier TOUZALIN
Annick Pucci
Delphine Largeteau
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G67/00—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only
    • C10G67/02—Treatment of hydrocarbon oils by at least one hydrotreatment process and at least one process for refining in the absence of hydrogen only plural serial stages only
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
    • C10G45/02—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing
    • C10G45/04—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing characterised by the catalyst used
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
    • C10G45/02—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing
    • C10G45/04—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing characterised by the catalyst used
    • C10G45/06—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing characterised by the catalyst used containing nickel or cobalt metal, or compounds thereof
    • C10G45/08—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to eliminate hetero atoms without changing the skeleton of the hydrocarbon involved and without cracking into lower boiling hydrocarbons; Hydrofinishing characterised by the catalyst used containing nickel or cobalt metal, or compounds thereof in combination with chromium, molybdenum, or tungsten metals, or compounds thereof
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G65/00—Treatment of hydrocarbon oils by two or more hydrotreatment processes only
    • C10G65/02—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only
    • C10G65/04—Treatment of hydrocarbon oils by two or more hydrotreatment processes only plural serial stages only including only refining steps
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1037—Hydrocarbon fractions
    • C10G2300/104—Light gasoline having a boiling range of about 20 - 100 °C
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1037—Hydrocarbon fractions
    • C10G2300/1044—Heavy gasoline or naphtha having a boiling range of about 100 - 180 °C
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1037—Hydrocarbon fractions
    • C10G2300/1048—Middle distillates
    • C10G2300/1051—Kerosene having a boiling range of about 180 - 230 °C
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1037—Hydrocarbon fractions
    • C10G2300/1048—Middle distillates
    • C10G2300/1055—Diesel having a boiling range of about 230 - 330 °C
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1037—Hydrocarbon fractions
    • C10G2300/1048—Middle distillates
    • C10G2300/1059—Gasoil having a boiling range of about 330 - 427 °C
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/20—Characteristics of the feedstock or the products
    • C10G2300/201—Impurities
    • C10G2300/202—Heteroatoms content, i.e. S, N, O, P
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
    • C10G2400/02—Gasoline
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
    • C10G2400/04—Diesel oil
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
    • C10G2400/06—Gasoil

Definitions

  • the present invention relates to a process for the simultaneous production of two cuts of hydrocarbons with low sulfur contents.
  • the process makes it possible to desulfurize jointly (as a mixture) a gasoline cut containing olefins and a cut heavier than the gasoline cut so as to subsequently produce a desulfurized gasoline cut with a limited loss of octane number and a heavy cut also desulfurized.
  • the present invention is particularly interesting for producing two desulfurized cuts which can be sent respectively to the gasoline pool and to the diesel, kerosene and/or fuel oil pool.
  • Sulfur in fuels is an undesirable impurity because it is converted to sulfur oxides when these products are burned.
  • Sulfur oxides are unwanted air pollutants that can further deactivate most catalysts that have been developed for catalytic converters used in cars to catalyze the conversion of harmful exhaust gases. Therefore, it is desirable to reduce the sulfur content of products used in gasoline and diesel fuel compositions to the lowest possible levels.
  • Catalytic cracking gasoline is the essential product of FCC (FCC "Fluid Catalytic Cracking” according to Anglo-Saxon terminology) obtained with a yield of around 50% and represents approximately 25 to 30% of the gasoline pool of refineries. 'Western Europe.
  • FCC Fluid Catalytic Cracking
  • the main negative characteristic of these FCC gasolines compared to commercial fuels is their high sulfur contents and thus constitute the main vector of the presence of sulfur in fuels.
  • hydrocarbons produced from catalytic cracking processes are conventionally treated by hydrotreating.
  • the hydrotreating process includes contacting the hydrocarbon feed with hydrogen in the presence of a catalyst so as to convert the sulfur contained in the impurities into hydrogen sulfide, which can then be separated and converted in elemental sulfur.
  • Hydrotreating processes can result in partial destruction of feedstock olefins by converting them to saturated hydrocarbons through hydrogenation. This destruction of olefins by hydrogenation is not desirable in the case of cracked gasolines because it results in costly hydrogen consumption and a significant reduction in the octane number of hydrodesulfurized gasolines.
  • the residual sulfur compounds generally present in desulfurized gasoline can be separated into two distinct families: the non-hydrodesulfurized sulfur compounds present in the feed and the sulfur compounds formed in the hydrodesulfurization reactor by secondary reactions known as recombination.
  • the majority compounds are the mercaptans resulting from the addition of the H 2 S formed in the reactor to the mono-olefins present in the feed. Reducing the content of recombinant mercaptans can be achieved by catalytic hydrodesulphurization but at the cost of saturation of a significant part of the mono-olefins, which then leads to a sharp reduction in the octane number of the gasoline. as well as overconsumption of hydrogen.
  • the document process EP 902 078 thus treats a distillate resulting from an atmospheric distillation step.
  • This type of distillate contains practically no compounds olefinic hydrocarbons unlike the feed treated in the present invention, one of the cuts which compose it contains a significant content of olefins, typically greater than 20% by weight relative to the total weight of said cut.
  • the majority of recombinant sulfur compounds encountered in the process of the document EP 902 078 are therefore not mercaptans resulting from the addition of the H 2 S formed in the reactor to the mono-olefins present in the feed, but probably the result of the addition of the H 2 S formed to olefins resulting cracking reactions induced by the high temperature necessary for very deep desulphurization of the feed.
  • the solution recommended by the patent EP 902 078 consists of carrying out extensive hydrodesulfurization at high temperature in a first reactor followed by gentler hydrodesulfurization in a second reactor which makes it possible to eliminate any recombination mercaptans and/or olefins which would have been produced in the first reactor.
  • This way of operating is unsuitable for a feed containing gasoline from a conversion unit with a high olefin content because it risks causing significant hydrogenation of said olefins during the first step, thus inducing a loss of octane number. unwanted.
  • the document US 2013/0087484 describes a process for producing p-xylene from a mixture of naphtha and light cutting oil (LCO, “Light Cycle Oil” according to Anglo-Saxon terminology) from a catalytic cracking unit.
  • the process comprises a step of hydrodesulfurization of said mixture followed by fractionation of the desulfurized effluent into three cuts, namely, a light C 2 -C 4 cut, a naphtha cut and a heavy cut.
  • the intermediate naphtha cut is processed in a catalytic reforming unit to produce aromatics and the heavy cut is hydrocracked to give an aromatics-rich effluent which is recycled to the fractionation column.
  • the second hydrodesulfurization step is carried out at a temperature lower by at least 10°C, preferably by at least 20°C, than that of the first hydrodesulfurization step.
  • the prior art also includes the document FR 2811328 which teaches a process for hydrodesulfurization of a gasoline cut which can be a mixture of gasolines coming from different conversion processes such as steam cracking, coking or visbreaking processes or even gasolines directly resulting from the atmospheric distillation of petroleum.
  • An aim of the invention is to propose a hydrodesulfurization process which can respond to the problems of overcapacity of gasoline hydrodesulfurization units.
  • the boiling temperatures can fluctuate by plus or minus 5°C compared to the values mentioned.
  • the inventors have surprisingly observed that it is possible to jointly hydrodesulfurize a mixture containing a gasoline cut and a distillate cut loaded with sulfur and with a low olefin content in order to produce a gasoline cut with a low sulfur content, in particular in mercaptans, without significant loss of octane number and a cut of distillate depleted in sulfur which can then be upgraded to the diesel and/or kerosene pool or as fuel for maritime use.
  • the treatment in the first hydrodesulfurization step of the hydrocarbon mixture leads surprisingly to limit the formation of recombinant mercaptans, reaction products of the addition of H 2 S with the olefins, and thus to obtain at the end of the process a gasoline cut having a very low mercaptan content.
  • the second hydrodesulfurization step is carried out under conditions which then favor the hydroconversion of the more refractory sulfur compounds which essentially come from the distillate cut.
  • the process according to the invention responds well to the problem of overcapacity of gasoline hydrodesulphurization units to the extent that these same units can now be used to jointly desulphurize gasoline cuts and middle distillate cuts which are bases for the formulation of fuels.
  • the invention therefore relates to a process implementing at least two successive hydrodesulphurization stages of a mixture of hydrocarbons consisting of a first and a second hydrocarbon fraction with an intermediate stage of elimination of the hydrogen sulfide (H 2 S) formed in the first hydrodesulfurization step and with a reaction temperature in the second hydrodesulfurization step which is higher than that in the first hydrodesulfurization step.
  • H 2 S hydrogen sulfide
  • the catalyst of step a) is a hydrodesulfurization catalyst which comprises a Group VIII metal chosen from nickel and cobalt and a Group VIB metal chosen from molybdenum and tungsten.
  • the catalyst of step c) is also a hydrodesulfurization catalyst which comprises a metal from group VIII chosen from nickel and cobalt and a metal from group VIB chosen from molybdenum and tungsten.
  • the first fraction of hydrocarbons containing olefins is an olefinic gasoline cut from a catalytic cracking, steam cracking, coking, visbreaking unit.
  • the second hydrocarbon fraction of the mixture treated by the process according to the invention is a light oil cut from a catalytic cracking unit (LCO or "Light Cycle Oil” according to Anglo-Saxon terminology).
  • LCO catalytic cracking unit
  • the feed for the process according to the invention is a mixture containing a catlaytic cracked gasoline cut and an LCO light oil cut.
  • said mixture is the product of a distillation of an effluent from a catalytic cracking unit.
  • the light fraction of the LCO i.e. the compounds having a boiling point lower than 300°C, and very preferably lower than 265°C, is used in mixture with the catalytic cracking gasoline.
  • the first fraction or hydrocarbon cut represents between 30 and 70% by weight of the mixture.
  • the first fraction of the mixture is a heavy fraction of a catalytic cracked gasoline and the second fraction is a cut of light LCO oil.
  • the heavy fraction of catalytically cracked gasoline is obtained by distillation of a catalytically cracked gasoline cut into two fractions, a light C5- fraction comprising hydrocarbons having a number of carbon atoms of between 2 and 5 atoms and a heavy C6+ fraction comprising hydrocarbons having a number of atoms of carbon greater than or equal to 6.
  • said gasoline cut is treated in a step of selective hydrogenation of the diolefins.
  • the first cut of hydrocarbons treated by the process according to the invention is sent via line 1 to a first hydrodesulphurization reactor 2.
  • This first cut of hydrocarbons is combined (mixed) with a second cut of hydrocarbons supplied by line 3.
  • the mixture which is made up of two fractions, is then treated in the first hydrodesulfurization reactor 2.
  • the first hydrocarbon cut an olefinic gasoline cut from a catalytic cracking, steam cracking, coking, visbreaking unit.
  • the gasoline cut is a catalytic cracked gasoline.
  • the gasoline cut has an initial boiling temperature of between 35°C and 100°C and a final boiling temperature of between 130 and 200°C, preferably between 150 and 170°C and more preferably between 155 and 165°C.
  • the olefin content of the first cut (or first fraction making up the mixture) is between 20 and 80% by weight of said cut.
  • the second hydrocarbon cut has an initial boiling temperature of approximately 160°C and the final boiling temperature of between 260 and 340°C and comprises a fraction of at least 10% by weight of hydrocarbons having a temperature boiling temperature between 220°C and its final boiling temperature.
  • This second hydrocarbon cut is a light oil cut from a catalytic cracking unit (LCO or “Light Cycle Oil” according to Anglo-Saxon terminology).
  • LCO catalytic cracking unit
  • This second cut has an olefin content lower than that of the first cut and a total sulfur content higher than that of the first cut.
  • said second fraction comprises at least 10% by weight of hydrocarbons having a boiling temperature range between 220°C and the final boiling temperature of the mixture.
  • the first hydrodesulfurization step converts part of the sulfur present in the mixture into hydrogen sulfide (H 2 S). It consists of passing the mixture of hydrocarbons to be treated in the presence of hydrogen (supplied via line 4), over a hydrodesulphurization catalyst, at a temperature between 200°C and 400°C, preferably between 250°C. C and 340°C and at a pressure of between 1 and 10 MPa, preferably between 1.5 and 4 MPa.
  • the liquid space velocity is generally between 1 and 10 h -1 , preferably between 2 and 5 h -1 and the H 2 /HC ratio is between 50 Nliters/liter (l/l) and 500 Nliters/liter, preferably between 100 Nliters/liter and 450 Nliters/liter, and more preferably between 150 Nliters/liter and 400 Nliters/liter.
  • the H 2 /HC ratio is the ratio between the volume flow rate of hydrogen under 1 atmosphere and at 0°C and the volume flow rate of hydrocarbons.
  • the effluent resulting from this hydrodesulfurization step withdrawn by line 5 comprises the mixture of partially desulfurized hydrocarbons, the residual hydrogen and the H 2 S produced by decomposition of sulfur compounds.
  • This hydrodesulfurization step is carried out for example in a fixed bed or moving bed reactor.
  • the catalyst used during the first hydrodesulfurization step of the hydrodesulfurization process according to the invention comprises an active metal phase deposited on a support, said active phase comprising at least one metal from group VIII of the periodic table of elements (groups 8, 9 and 10 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ) and at least one metal from group VIB of the periodic table of elements (group 6 according to the new notation of the periodic table of elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ).
  • the active phase of said catalyst further comprises phosphorus.
  • the catalyst of the first hydrodesulfurization step may also additionally contain one or more organic compounds.
  • the content of metal(s) from group VIB in said catalyst of the first hydrodesulfurization step is between 4 and 40% by weight of oxide(s) of metal(s) from group VIB, preferably between 8 and 35% by weight of metal oxide(s) from group VIB, very preferably between 10 and 30% by weight of metal oxide(s) from group VIB relative to the total weight of the catalyst.
  • the Group VIB metal is molybdenum or tungsten or a mixture of these two elements, and more preferably the Group VIB metal consists solely of molybdenum or tungsten.
  • the Group VIB metal is most preferably molybdenum.
  • the content of metal(s) from Group VIII in said catalyst of the first hydrodesulfurization step is between 1.5 and 9% by weight of oxide(s) of metal(s) from Group VIII, of preferably between 2 and 8% by weight of oxide(s) of metal(s) from Group VIII relative to the total weight of the catalyst.
  • the group VIII metal is a non-noble metal from group VIII of the periodic table of elements.
  • said Group VIII metal is cobalt or nickel or a mixture of these two elements, and more preferably the Group VIII metal consists solely of cobalt or nickel.
  • the Group VIII metal is most preferably cobalt.
  • the molar ratio of metal(s) from group VIII to metal(s) from group VIB in the catalyst in oxide form is between 0.1 and 0.8, very preferably between 0.2 and 0.6, and so even more preferred between 0.3 and 0.5.
  • the phosphorus content of the catalyst of the first hydrodesulfurization step is preferably between 0.1 and 20% by weight of P 2 O 5 , more preferably between 0.2 and 15% by weight of P 2 O 5 , very preferably between 0.3 and 10% by weight of P 2 O 5 relative to the total weight of the catalyst.
  • the molar ratio of phosphorus to metal(s) of group VIB in the catalyst of the first hydrodesulfurization step is greater than or equal to 0.05, preferably greater than or equal to 0.1, more preferably between 0.15 and 0.6, even more preferably between 0.15 and 0.5.
  • the support of the catalyst of the first hydrodesulfurization step on which the active phase is deposited is advantageously formed of at least one porous solid in oxide form chosen from the group consisting of aluminas, silicas, silica-alumina or even titanium or magnesium oxides used alone or mixed with alumina or silica-alumina. It is preferably chosen from the group consisting of silicas, transition aluminas and silica-alumina. More preferably, said support consists solely of a transition alumina or of a mixture of transition aluminas.
  • the specific surface area of the catalyst is generally between 100 and 400 m 2 /g, preferably between 150 and 300 m 2 /g.
  • the catalyst of the first hydrodesulfurization step is advantageously in the form of beads, extrudates, pellets, or irregular and non-spherical agglomerates whose specific shape can result from a crushing step.
  • said support is in the form of balls or extrudates.
  • the catalyst of the first hydrodesulfurization step is preferably used at least partly in its sulfurized form.
  • Sulfurization consists of passing a charge containing at least one sulfur compound, which once decomposed leads to the fixation of sulfur on the catalyst.
  • This charge can be gaseous or liquid, for example hydrogen containing H 2 S, or a liquid containing at least one sulfur compound.
  • the sulfurization step can be carried out in situ, that is to say within the process according to the invention, or ex situ, that is to say in a unit dedicated to the sulfurization of catalysts.
  • the process comprises a step where the H 2 S is at least partly eliminated from the effluent obtained at the end of the first hydrodesulfurization step.
  • This step can be carried out using any techniques known to those skilled in the art. It can be carried out directly in the conditions in which the effluent is found at the end of this step or after the conditions have been changed in order to facilitate the elimination of at least part of the H 2 S.
  • a gas/liquid separation following which the liquid effluent is sent to a stripping column while the gaseous effluent is sent to a stage of amine wash.
  • the effluent from the reactor of the first hydrodesulphurization stage is sent via line 5 to a stripping column 6 which makes it possible to separate at the top of the column a gaseous flow 7 containing hydrogen and H 2 S and at the bottom an effluent containing a mixture of hydrocarbons 8 partially desulfurized and freed of H 2 S.
  • a mixture of hydrocarbons is obtained having a total sulfur content of between 100 and 1000 ppm by weight, preferably between 200 and 500 ppm by weight.
  • the effluent comprising the partially desulfurized hydrocarbon mixture is treated in an additional hydrodesulfurization step (HDS) aimed at improving the final desulfurization rate.
  • This second step aims to transform the refractory sulfur compounds present in the mixture and which are essentially provided by the second cut implemented in the process according to the invention.
  • the effluent is sent via line 8 to a hydrodesulfurization reactor 9 and is brought into contact with a hydrodesulfurization catalyst in the presence of hydrogen supplied by line 10.
  • the temperature of the second HDS stage is higher than that of the first HDS stage, preferably higher by at least 5°C and even more preferably by at least 10°C.
  • the second hydrodesulfurization step uses a catalyst having a selectivity in hydrodesulfurization with respect to the hydrogenation of olefins greater than the catalyst of the first hydrodesulfurization step.
  • the catalyst suitable for this second hydrodesulfurization step comprises at least one metal from group VIII (groups 8, 9 and 10 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ) and at least one metal from group VIB (group 6 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ) on an appropriate support.
  • the Group VIII metal content expressed as oxide is generally between 0.5 and 15% by weight, preferably between 1 and 10% by weight relative to the total weight of catalyst.
  • the metal content of group VIB is generally between 1.5 and 60% by weight, preferably between 3 and 50% by weight per contribution to the total weight of catalyst.
  • the Group VIII metal is preferably cobalt and the Group VIB metal is generally molybdenum or tungsten.
  • the catalyst for the second hydrodesulfurization step further comprises phosphorus.
  • the phosphorus content of said catalyst is preferably between 0.1 and 20% by weight of P 2 O 5 , more preferably between 0.2 and 15% by weight of P 2 O 5 , very preferably between 0.3 and 10% by weight of P 2 O 5 relative to the total weight of the catalyst.
  • the catalyst further comprises one or more organic compounds.
  • the catalyst support is usually a porous solid, such as for example alumina, silica-alumina or other porous solids, such as for example magnesia, silica or titanium oxide, alone or in combination. mixture with alumina or silica-alumina.
  • a porous solid such as for example alumina, silica-alumina or other porous solids, such as for example magnesia, silica or titanium oxide, alone or in combination. mixture with alumina or silica-alumina.
  • the catalyst according to the invention preferably has a specific surface area less than 200 m 2 /g, more preferably less than 180 m 2 /g, and very preferably less than 150 m 2 /g.
  • the catalyst of the second hydrodesulfurization step is preferably used at least partly in its sulfurized form.
  • Sulfurization consists of passing the charge containing at least one sulfur compound, which once decomposed leads to the fixation of sulfur on the catalyst.
  • This charge can be gaseous or liquid, for example hydrogen containing H 2 S, or a liquid containing at least one sulfur compound.
  • the sulfurization step can be carried out in situ, that is to say within the process according to the invention, or ex situ, that is to say in a unit dedicated to the sulfurization of catalysts.
  • the desulfurized effluent has a total sulfur content generally less than 50 ppm by weight, preferably less than 30 ppm by weight and has a mercaptan content generally less than 10 ppm by weight.
  • the effluent which is withdrawn from the second hydrodesulfurization reactor 9 is sent via line 11 to a separation unit 12.
  • the effluent from the reactor is first sent to a balloon gas/liquid separation allowing the separation of a gas rich in H 2 S from the liquid effluent.
  • This liquid effluent is then sent to a stabilization column in order to eliminate the last traces of solubilized H 2 S and produce a stabilized column bottom product, that is to say whose vapor pressure has been corrected by elimination of the lightest hydrocarbon compounds.
  • the gas/liquid separation and stabilization steps are classic steps for those skilled in the art and are not shown on the figure 1 .
  • the separation or distillation step consists of separating the stabilized effluent containing the mixture of hydrocarbons into at least two hydrocarbon cuts, namely a cut light hydrocarbons and a heavy hydrocarbon cut both desulfurized.
  • the cutting point is generally between 160°C and 220°C, limits included.
  • the separation unit used is a distillation column configured to separate at the top of the column a light desulphurized cut 13, equivalent to a gasoline cut and at the bottom a heavy desulphurized cut 14 equivalent to a distillate cut.
  • the gasoline cut is sent to the gasoline pool and the desulfurized distillate cut is sent to the diesel, kerosene or fuel oil pool.
  • the sulfur content in the desulfurized light cut is less than 50 ppm by weight, preferably less than 30 ppm by weight and even more preferably less than 10 ppm by weight.
  • the sulfur content in the desulfurized heavy cut is less than 50 ppm by weight, optionally less than 30 ppm by weight or even less than 10 ppm by weight.
  • distillate cut is recovered at the bottom, the gasoline cut is withdrawn laterally several trays below the top tray while the lightest compounds are eliminated at the top of the column in the gaseous effluent.
  • the effluent from the stabilization column containing the desulfurized hydrocarbon mixture is separated into three cuts.
  • the two cutting points will generally be around 160°C and around 220°C.
  • the three hydrocarbon cuts have a total sulfur content of less than 50 ppm by weight, preferably less than 30 ppm by weight and even more preferably less than 10 ppm by weight.
  • a first cut of gasoline type hydrocarbons is sent to a pretreatment reactor 15 before being mixed with a second cut of hydrocarbons.
  • the hydrocarbon feedstock is preferably a catalytically cracked gasoline cut which generally contains diolefins at a content of between 0.1 and 3% by weight.
  • the pretreatment consists of a step of selective hydrogenation of the diolefins into corresponding mono-olefins, which is carried out in the presence of a catalyst and hydrogen.
  • the catalyst for selective hydrogenation of diolefins suitable for pretreatment comprises at least one metal from group VIB and at least one metal from group VIII deposited on a porous support described in the patent applications FR 2 988 732 And EP 2 161 076 of the plaintiff.
  • the catalytic selective hydrogenation reaction is generally carried out in the presence of hydrogen, at a temperature between 80°C and 220°C, and preferably between 90°C and 200°C, with a liquid space velocity (LHSV) comprised between 1 and 10 h -1 , the unit of liquid space velocity being the liter of charge per liter of catalyst and per hour (l/lh).
  • the operating pressure is between 0.5 MPa and 5 MPa, preferably between 1 and 4 MPa.
  • the gasoline produced contains less than 0.5% by weight of diolefins, and preferably less than 0.25% by weight of diolefins.
  • the first pretreated hydrocarbon cut is directed via line 16 to a separation column 17 (splitter according to Anglo-Saxon terminology) which is designed to split said pretreated charge respectively into a light fraction C5 - and a heavy fraction C6+.
  • the light fraction is advantageously sent to the gasoline pool via line 18, while the heavy C6+ fraction entering line 1 is hydrodesulfurized by the process described above, that is to say mixed with a cut of middle distillate at low olefin content.
  • An ⁇ hydrodesulfurization catalyst is obtained by impregnation “without excess solution” of a transition alumina in the form of beads with a specific surface area of 130 m 2 /g and a pore volume of 0.9 ml/g, by a aqueous solution containing molybdenum and cobalt in the form of ammonium heptamolybdate and cobalt nitrate.
  • the catalyst is then dried and calcined in air at 500°C.
  • the cobalt and molybdenum content of the ⁇ catalyst is 3% by weight of CoO and 10% by weight of MoOs.
  • the catalyst is first sulfurized by treatment for 4 hours under a pressure of 3.4 MPa at 350°C, in contact with a charge consisting of 2% by weight of sulfur in the form of dimethyldisulfide in n-heptane.
  • the treated feed C is a catalytic cracked gasoline whose initial boiling point is 61°C and the final point is 162°C. Its sulfur content is 765 ppm by weight and its bromine index (IBr) is 75.9 g/100 g, which corresponds approximately to 42% by weight of olefins.
  • This charge C is treated with the catalyst ⁇ , under a pressure of 2 MPa, a volume ratio of hydrogen to charge to be treated (H 2 /HC) of 300 NI/l and a VVH of 4 h -1 .
  • H 2 /HC volume ratio of hydrogen to charge to be treated
  • VVH VVH of 4 h -1
  • the effluent is cooled and the hydrogen rich in H 2 S is separated from the liquid gasoline, and the gasoline is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate the residual traces of H 2 S dissolved in the desulfurized gasoline.
  • Table 1 shows the influence of the temperature involved on the desulfurization rates and the RON index of the desulfurized effluents.
  • Table 1 Analysis of desulfurized gasoline Temperature in the hydrodesulfurization reactor, 285 °C Temperature in the hydrodesulfurization reactor, 295 °C Mercaptans, ppm weight 16 7 Total sulfur, ppm weight 25 12 Desulfurization rate, % 96.7 98.4 RON loss 6.9 8.4
  • a ⁇ hydrodesulfurization catalyst in the form of extrudates with a specific surface area of 180 m 2 /g whose content (weight of oxide(s) relative to the total weight of the catalyst) in cobalt, molybdenum and phosphorus are respectively 4.4% by weight of CoO and 21.3% by weight of MoO 3 and 6.0% by weight of P 2 O 5 are placed in a fixed bed tubular hydrodesulfurization reactor.
  • the catalyst is first sulfurized by treatment for 4 hours under a pressure of 2 MPa at 350°C, in contact with a filler consisting of 2% by weight of sulfur in the form of dimethyldisulfide in n-heptane.
  • the treated feed D has an initial boiling point of 160°C and an end point of 269°C. Its sulfur content is 5116 ppm by weight and its bromine index (IBr) is 19.5 g/100 g which corresponds approximately to 10% by weight of olefins.
  • the fraction of charge D having a boiling point between 220°C and 269°C is 26.3% by weight.
  • Charge D is treated with catalyst ⁇ , at a temperature of 300°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to charge to be treated (H 2 /HC) of 300 NI/I and a VVH of 4 h -1 .
  • H 2 /HC volume ratio of hydrogen to charge to be treated
  • the effluent is cooled, the hydrogen rich in H 2 S is separated from the liquid effluent, and the effluent is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate the residual traces of dissolved H 2 S before being analyzed.
  • Table 2 shows the desulfurization rate and the sulfur and mercaptan content of the desulfurized effluent.
  • Table2 Analysis Mercaptans, ppm weight 12 Total sulfur, ppm weight 34 Desulfurization rate, % 99.3
  • a charge E tested in Example 3 is a mixture containing 50% by weight of charge C and 50% by weight of charge D.
  • the initial boiling point of the mixture is 61°C and the final point is 269°C. vs.
  • Its sulfur content is 2512 ppm by weight and its bromine index (IBr) is 53.4 g/100 g which corresponds approximately to 29.2% by weight of olefins.
  • This charge E is first treated on the catalyst ⁇ , at a temperature of 330°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to charge to be treated (H 2 /HC) of 300 NI/I and a VVH from 4 a.m. -1 .
  • H 2 /HC volume ratio of hydrogen to charge to be treated
  • VVH VVH from 4 a.m. -1 .
  • the feed E used in Example 3 is treated in a first hydrodesulfurization step on the catalyst ⁇ , at a temperature of 260°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to feed to be treated (H 2 /HC) of 300 NI/I and a VVH of 4 h -1 .
  • H 2 /HC volume ratio of hydrogen to feed to be treated
  • VVH volume ratio of hydrogen to feed to be treated
  • the feedstock F is then treated in a second hydrodesulfurization step on the ⁇ catalyst, at a temperature of 280°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to feedstock to be treated (H 2 /HC) of 300. l/l and a VVH of 4 h -1 .
  • H 2 /HC volume ratio of hydrogen to feedstock to be treated
  • VVH volume ratio of hydrogen to feedstock to be treated
  • the effluent from the second hydrodesulfurization stage is then separated into two cuts: a first cut (petrol cut) with a final boiling point of 160°C and a second cut with an initial point of 160°C.
  • a first cut petrol cut
  • a second cut with an initial point of 160°C.
  • Table 4 References 1st cut 2nd cut 61°C-160°C 160°C-269°C Mercaptans, ppm weight 7 11 Total sulfur, ppm weight 9 42 Desulfurization rate, % 98.8 99.2 RON loss 5.9 Not applicable
  • Example 4 shows that it is possible, from a mixture of hydrocarbons comprising at least a first cut of hydrocarbons having a boiling temperature of between 61° and 160°C and whose olefin content is of 42% by weight and a second cut of hydrocarbons having a boiling point between 160° and 269°C of which the fraction having a boiling point greater than 220°C is 26.3%, to obtain two desulphurized cuts whose sulfur content are respectively less than 10 ppm by weight of sulfur for the desulphurized cut having a boiling temperature between 61°C and 160°C and less than 50 ppm by weight of sulfur for the desulphurized cut having a temperature of boiling between 160° and 269°C while limiting the loss of RON index linked in particular to the hydrogenation of part of the olefins present in the mixture.

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Description

La présente invention concerne un procédé de production concomitante de deux coupes d'hydrocarbures à basses teneurs en soufre. En particulier le procédé permet de désulfurer conjointement (en mélange) une coupe essence contenant des oléfines et une coupe plus lourde que la coupe essence de manière à produire par la suite une coupe essence désulfurée avec une perte d'indice d'octane limitée et une coupe lourde également désulfurée.The present invention relates to a process for the simultaneous production of two cuts of hydrocarbons with low sulfur contents. In particular, the process makes it possible to desulfurize jointly (as a mixture) a gasoline cut containing olefins and a cut heavier than the gasoline cut so as to subsequently produce a desulfurized gasoline cut with a limited loss of octane number and a heavy cut also desulfurized.

La présente invention est notamment intéressante pour produire deux coupes désulfurées qui sont susceptibles d'être envoyées respectivement au pool essence et au pool diesel, kérosène et/ou fioul.The present invention is particularly interesting for producing two desulfurized cuts which can be sent respectively to the gasoline pool and to the diesel, kerosene and/or fuel oil pool.

Etat de la techniqueState of the art

Le soufre dans les carburants est une impureté indésirable car il est converti en oxydes de soufre lorsque ces produits sont brûlés. Les oxydes de soufre sont des polluants atmosphériques indésirables qui peuvent en outre désactiver la plupart des catalyseurs qui ont été développés pour les pots catalytiques utilisés dans les voitures pour catalyser la conversion des gaz d'échappement nocifs. Par conséquent, il est souhaitable de réduire la teneur en soufre des produits qui entrent dans les compositions de la carburante essence et gazole à des niveaux les plus bas possibles.Sulfur in fuels is an undesirable impurity because it is converted to sulfur oxides when these products are burned. Sulfur oxides are unwanted air pollutants that can further deactivate most catalysts that have been developed for catalytic converters used in cars to catalyze the conversion of harmful exhaust gases. Therefore, it is desirable to reduce the sulfur content of products used in gasoline and diesel fuel compositions to the lowest possible levels.

L'essence de craquage catalytique est le produit essentiel du FCC (FCC "Fluid Catalytic Cracking" selon la terminologie anglo-saxonne) obtenu avec un rendement de l'ordre de 50% et représente environ 25 à 30% du pool essence des raffineries d'Europe Occidentale. La principale caractéristique négative de ces essences de FCC vis-à-vis des carburants commerciaux est leurs teneurs en soufre élevées et constituent ainsi le principal vecteur de la présence de soufre dans les carburants.Catalytic cracking gasoline is the essential product of FCC (FCC "Fluid Catalytic Cracking" according to Anglo-Saxon terminology) obtained with a yield of around 50% and represents approximately 25 to 30% of the gasoline pool of refineries. 'Western Europe. The main negative characteristic of these FCC gasolines compared to commercial fuels is their high sulfur contents and thus constitute the main vector of the presence of sulfur in fuels.

Pour répondre aux contraintes des spécifications en soufre, les hydrocarbures produits à partir de procédés de craquage catalytique sont classiquement traités par hydrotraitement. Le procédé d'hydrotraitement comprend la mise en contact de la charge d'hydrocarbures avec de l'hydrogène en présence d'un catalyseur de manière à convertir le soufre contenu dans les impuretés en sulfure d'hydrogène, qui peut être ensuite séparé et converti en soufre élémentaire. Les procédés d'hydrotraitement peuvent entraîner une destruction partielle des oléfines de la charge en les convertissant en hydrocarbures saturés par hydrogénation. Cette destruction d'oléfines par hydrogénation n'est pas souhaitable dans le cas des essences de craquage car il en résulte une consommation coûteuse en hydrogène et une diminution significative de l'indice d'octane des essences hydrodésulfurées.To meet the constraints of sulfur specifications, hydrocarbons produced from catalytic cracking processes are conventionally treated by hydrotreating. The hydrotreating process includes contacting the hydrocarbon feed with hydrogen in the presence of a catalyst so as to convert the sulfur contained in the impurities into hydrogen sulfide, which can then be separated and converted in elemental sulfur. Hydrotreating processes can result in partial destruction of feedstock olefins by converting them to saturated hydrocarbons through hydrogenation. This destruction of olefins by hydrogenation is not desirable in the case of cracked gasolines because it results in costly hydrogen consumption and a significant reduction in the octane number of hydrodesulfurized gasolines.

Les composés soufrés résiduels généralement présents dans l'essence désulfurée peuvent être séparés en deux familles distinctes : les composés soufrés non hydrodésulfurés présents dans la charge et les composés soufrés formés dans le réacteur d'hydrodésulfuration par des réactions secondaires dites de recombinaison. Parmi cette dernière famille de composés soufrés, les composés majoritaires sont les mercaptans issus de l'addition de l'H2S formé dans le réacteur sur les mono-oléfines présentes dans la charge. La réduction de la teneur en mercaptans de recombinaison peut être réalisée par hydrodésulfuration catalytique mais au prix d'une saturation d'une partie importante des mono-oléfines, ce qui entraîne alors une forte diminution de l'indice d'octane de l'essence ainsi qu'une surconsommation d'hydrogène.The residual sulfur compounds generally present in desulfurized gasoline can be separated into two distinct families: the non-hydrodesulfurized sulfur compounds present in the feed and the sulfur compounds formed in the hydrodesulfurization reactor by secondary reactions known as recombination. Among this last family of sulfur compounds, the majority compounds are the mercaptans resulting from the addition of the H 2 S formed in the reactor to the mono-olefins present in the feed. Reducing the content of recombinant mercaptans can be achieved by catalytic hydrodesulphurization but at the cost of saturation of a significant part of the mono-olefins, which then leads to a sharp reduction in the octane number of the gasoline. as well as overconsumption of hydrogen.

De nos jours, dans de nombreux pays et en particulier en Europe, le marché des carburants s'est essentiellement orienté vers celui du diesel et du kérosène, ce qui a pour effet que de nombreux raffineurs européens sont confrontés à des problèmes de surcapacité pour leurs unités dédiées à la production de coupes essence désulfurées et de sous capacité vis-à-vis des unités d'hydrodésulfuration qui traitent des coupes de distillats intermédiaires rentrant dans la composition du carburant diesel et/ou kérosène.Nowadays, in many countries and particularly in Europe, the fuel market has mainly shifted towards that of diesel and kerosene, which has the effect that many European refiners are faced with overcapacity problems for their units dedicated to the production of desulphurized gasoline cuts and undercapacity vis-à-vis hydrodesulphurization units which process intermediate distillate cuts used in the composition of diesel and/or kerosene fuel.

Il existe donc aujourd'hui un besoin pour des procédés qui permettent au raffineur de mieux répondre à la demande du marché en utilisant les surcapacités existantes au niveau des unités d'hydrodésulfuration des coupes essences.There is therefore a need today for processes that allow the refiner to better respond to market demand by using existing excess capacity at the hydrodesulphurization units for gasoline cuts.

On connaît dans l'état de la technique le document EP 902 078 qui divulgue un procédé de traitement du pétrole brut qui comprend les étapes suivantes:

  • une étape de distillation atmosphérique du pétrole afin de séparer un distillat comprenant du gasoil et des fractions dont le point d'ébullition est inférieur à celui du gasoil;
  • une première étape d'hydrodésulfuration du distillat;
  • une seconde étape d'hydrodésulfuration du distillat partiellement désulfuré qui est réalisée à une température inférieure à celle de la première étape d'hydrodésulfuration; et
  • une étape de séparation du distillat désulfuré en des fractions de gasoil, de kérosène, de naphta lourd et de naphta léger.
We know in the state of the art the document EP 902 078 which discloses a process for processing crude oil which comprises the following steps:
  • an atmospheric petroleum distillation step in order to separate a distillate comprising gas oil and fractions whose boiling point is lower than that of the gas oil;
  • a first step of hydrodesulfurization of the distillate;
  • a second step of hydrodesulfurization of the partially desulfurized distillate which is carried out at a temperature lower than that of the first hydrodesulfurization step; And
  • a step of separating the desulphurized distillate into fractions of diesel, kerosene, heavy naphtha and light naphtha.

Le procédé du document EP 902 078 traite ainsi un distillat issu d'une étape de distillation atmosphérique. Ce type de distillat ne contient pratiquement pas de composés hydrocarbures oléfiniques contrairement à la charge traitée dans la présente invention dont une des coupes qui la compose contient une teneur importante en oléfines, typiquement supérieure à 20% poids par rapport au poids total de ladite coupe. Les composés soufrés de recombinaison majoritaires rencontrés dans le procédé du document EP 902 078 ne sont donc pas des mercaptans issus de l'addition de l'H2S formé dans le réacteur sur les mono-oléfines présentes dans la charge, mais probablement le résultat de l'addition de l'H2S formé sur des oléfines issues de réactions de craquage induite par la température élevée nécessaire à la désulfuration très profonde de la charge. En effet, le naphta lourd issu de la distillation atmosphérique est généralement destiné à être converti dans une unité de reformage catalytique et doit par conséquent être désulfuré de manière poussée (la teneur en soufre total est typiquement inférieure à 1 ppm poids). Par contre la spécification en soufre admissible dans un pool essence est moins sévère (environ 10 ppm poids). L'homme du métier cherche donc dans le cas de l'hydrodésulfuration d'un distillat comprenant du gasoil et des fractions dont le point d'ébullition est inférieur à celui du gasoil issu d'une distillation atmosphérique, à maximiser la réaction d'hydrodésulfuration tout en évitant les réactions (notamment les réactions de craquage) susceptibles de former des oléfines.The document process EP 902 078 thus treats a distillate resulting from an atmospheric distillation step. This type of distillate contains practically no compounds olefinic hydrocarbons unlike the feed treated in the present invention, one of the cuts which compose it contains a significant content of olefins, typically greater than 20% by weight relative to the total weight of said cut. The majority of recombinant sulfur compounds encountered in the process of the document EP 902 078 are therefore not mercaptans resulting from the addition of the H 2 S formed in the reactor to the mono-olefins present in the feed, but probably the result of the addition of the H 2 S formed to olefins resulting cracking reactions induced by the high temperature necessary for very deep desulphurization of the feed. Indeed, heavy naphtha from atmospheric distillation is generally intended to be converted in a catalytic reforming unit and must therefore be extensively desulfurized (the total sulfur content is typically less than 1 ppm by weight). On the other hand, the admissible sulfur specification in a gasoline pool is less strict (around 10 ppm weight). Those skilled in the art therefore seek, in the case of the hydrodesulfurization of a distillate comprising gas oil and fractions whose boiling point is lower than that of gas oil resulting from atmospheric distillation, to maximize the hydrodesulfurization reaction. while avoiding reactions (in particular cracking reactions) likely to form olefins.

La solution préconisée par le brevet EP 902 078 consiste à réaliser une hydrodésulfuration poussée à haute température dans un premier réacteur suivi d'une hydrodésulfuration plus douce dans un second réacteur qui permet d'éliminer les éventuels mercaptans de recombinaison et/ou les oléfines qui auraient été produits dans le premier réacteur. Cette manière d'opérer est inadaptée à une charge contenant une essence issue d'une unité de conversion à haute teneur en oléfines car elle risque de provoquer une hydrogénation importante desdites oléfines lors de la première étape induisant ainsi une perte d'indice d'octane non souhaitée.The solution recommended by the patent EP 902 078 consists of carrying out extensive hydrodesulfurization at high temperature in a first reactor followed by gentler hydrodesulfurization in a second reactor which makes it possible to eliminate any recombination mercaptans and/or olefins which would have been produced in the first reactor. This way of operating is unsuitable for a feed containing gasoline from a conversion unit with a high olefin content because it risks causing significant hydrogenation of said olefins during the first step, thus inducing a loss of octane number. unwanted.

Le document US 2013/0087484 décrit un procédé de production de p-xylène à partir d'un mélange de naphta et d'huile de coupe légère (LCO, "Light Cycle Oil" selon la terminologie anglo-saxonne) issus d'une unité de craquage catalytique. Le procédé comprend une étape d'hydrodésulfuration dudit mélange suivie d'un fractionnement de l'effluent désulfuré en trois coupes à savoir, une coupe légère C2-C4, une coupe naphta et une coupe lourde. La coupe naphta intermédiaire est traitée dans une unité de reformage catalytique pour produire des composés aromatiques et la coupe lourde est hydrocraquée pour donner un effluent riche en aromatiques qui est recyclé dans la colonne de fractionnement.The document US 2013/0087484 describes a process for producing p-xylene from a mixture of naphtha and light cutting oil (LCO, “Light Cycle Oil” according to Anglo-Saxon terminology) from a catalytic cracking unit. The process comprises a step of hydrodesulfurization of said mixture followed by fractionation of the desulfurized effluent into three cuts, namely, a light C 2 -C 4 cut, a naphtha cut and a heavy cut. The intermediate naphtha cut is processed in a catalytic reforming unit to produce aromatics and the heavy cut is hydrocracked to give an aromatics-rich effluent which is recycled to the fractionation column.

Le document FR 2837831 décrit un procédé d'hydrodésulfuration d'une coupe essence issue du craquage catalytique ou de la cokéfaction d'une charge lourde hydrocarbonée mettant en jeu :

  • une première étape d'hydrodésulfuration de ladite coupe essence;
  • une étape de séparation de la majeure partie de l'H2S de l'effluent issu de la première hydrodésulfuration;
  • une seconde étape d'hydrodésulfuration de ladite coupe essence débarrassée de l'H2S.
The document FR 2837831 describes a process for hydrodesulfurization of a gasoline cut resulting from catalytic cracking or coking of a heavy hydrocarbon feed involving:
  • a first step of hydrodesulfurization of said gasoline cut;
  • a step of separating the majority of the H 2 S from the effluent resulting from the first hydrodesulfurization;
  • a second step of hydrodesulfurization of said gasoline cut freed of H 2 S.

Selon ce document, la seconde étape d'hydrodésulfuration est conduite à une température inférieure d'au moins 10°C, de préférence d'au moins 20°C à celle de la première étape d'hydrodésulfuration.According to this document, the second hydrodesulfurization step is carried out at a temperature lower by at least 10°C, preferably by at least 20°C, than that of the first hydrodesulfurization step.

L'art antérieur comprend également le document FR 2811328 qui enseigne un procédé d'hydrodésulfuration d'une coupe essence qui peut être un mélange d'essences provenant de différents procédés de conversion tels que les procédés de vapocraquage, de cokéfaction ou de viscoréduction voire des essences directement issues de la distillation atmosphérique du pétrole.The prior art also includes the document FR 2811328 which teaches a process for hydrodesulfurization of a gasoline cut which can be a mixture of gasolines coming from different conversion processes such as steam cracking, coking or visbreaking processes or even gasolines directly resulting from the atmospheric distillation of petroleum.

Un but de l'invention est de proposer un procédé d'hydrodésulfuration qui puisse répondre aux problèmes de surcapacités des unités d'hydrodésulfuration des essences.An aim of the invention is to propose a hydrodesulfurization process which can respond to the problems of overcapacity of gasoline hydrodesulfurization units.

Résumé de l'inventionSummary of the invention

L'invention concerne donc un procédé de production concomitante de deux coupes d'hydrocarbures à basses teneurs en soufre à partir d'un mélange d'hydrocarbures ayant une température d'ébullition initiale comprise entre 35°C et 100°C et une température d'ébullition finale comprise entre 260°C et 340°C et ayant une teneur en soufre total comprise entre 30 et 10000 ppm poids, ledit mélange d'hydrocarbures est constitué de:

  • une première fraction comprenant des hydrocarbures ayant une gamme de températures d'ébullition comprise entre la température d'ébullition initiale du mélange et 160°C et dont la teneur en oléfines est comprise entre 20 et 80% poids de ladite première fraction et la première fraction étant choisie parmi une coupe essence oléfinique issue d'une unité de craquage catalytique, de vapocraquage, de cokéfaction, de viscoréduction, la première fraction représentant entre 30 et 70 % poids du mélange, et
  • une seconde fraction comprenant des hydrocarbures ayant une gamme de températures d'ébullition comprise entre 160°C et la température d'ébullition finale du mélange, ladite seconde fraction comprenant au moins 10% poids d'hydrocarbures ayant une gamme de températures d'ébullition comprise entre 220°C et la température d'ébullition finale du mélange, la seconde fraction étant une huile légère issue d'une unité de craquage catalytique,
le procédé comprenant les étapes suivantes:
  1. a) on traite dans un premier réacteur ledit mélange constitué de ladite première fraction et de ladite seconde fraction dans une première étape d'hydrodésulfuration en présence d'hydrogène et d'un catalyseur comprenant au moins un métal du groupe VIII, au moins un métal du groupe VIB et un support, la teneur en métal(ux) du groupe VIII étant comprise entre 1,5 et 9% poids d'oxyde(s) de métal(ux) du groupe VIII et la teneur en métal(ux) du groupe VIB étant comprise entre 4 et 40% poids d'oxyde(s) de métal(ux) du groupe VIB, le rapport molaire métal(ux) du groupe VIII sur métal(ux) du groupe VIB dans le catalyseur sous forme oxyde est compris entre 0,1 et 0,8, la première étape d'hydrodésulfuration étant réalisée à une température comprise entre 200 et 400°C, à une pression comprise entre 1 et 10 MPa, avec une vitesse spatiale liquide comprise entre 0,1 et 10 h-1 et avec un ratio (volume d'hydrogène / volume de mélange d'hydrocarbures) compris entre 50 et 500 Nlitre/litre;
  2. b) on élimine le sulfure d'hydrogène de l'effluent partiellement désulfuré issu de l'étape a);
  3. c) on traite dans un second réacteur le mélange partiellement désulfuré issu de l'étape b) dans une seconde étape d'hydrodésulfuration en présence d'hydrogène et d'un catalyseur comprenant au moins un élément du groupe VIII, au moins un élément du groupe VIB et un support, la teneur en métal(ux) du groupe VIII étant comprise entre 0,5 et 15% poids d'oxyde(s) de métal(ux) du groupe VIII et la teneur en métal(ux) du groupe VIB étant comprise entre 1,5 et 60% poids d'oxyde(s) de métal(ux) du groupe VIB, la seconde étape d'hydrodésulfuration étant réalisée à une température comprise entre 205 et 500°C, à une pression comprise entre 1 et 3 MPa, avec une vitesse spatiale liquide comprise entre 1 et 10 h-1 et avec un ratio (volume d'hydrogène / volume de mélange) compris entre 50 et 500 Nlitre/litre, la température de la seconde étape d'hydrodésulfuration c) étant supérieure à celle de la première étape d'hydrodésulfuration a); et
  4. d) on fractionne le mélange désulfuré issu de l'étape c) en au moins deux coupes d'hydrocarbures légère et lourde désulfurées, la coupe d'hydrocarbures légère ayant une température d'ébullition initiale comprise entre 35°C et 100°C et une température d'ébullition finale comprise entre 160°C et 220°C et dont la teneur en soufre total est inférieure à 50 ppm poids et la coupe d'hydrocarbures lourde ayant une température d'ébullition initiale comprise entre 160°C et 220°C et une température d'ébullition finale comprise entre 260°C et 340°C.
The invention therefore relates to a process for the simultaneous production of two cuts of hydrocarbons with low sulfur contents from a mixture of hydrocarbons having an initial boiling temperature of between 35°C and 100°C and a temperature of final boiling point of between 260°C and 340°C and having a total sulfur content of between 30 and 10,000 ppm by weight, said mixture of hydrocarbons consists of:
  • a first fraction comprising hydrocarbons having a range of boiling temperatures between the initial boiling temperature of the mixture and 160°C and whose olefin content is between 20 and 80% by weight of said first fraction and the first fraction being chosen from an olefinic gasoline cut from a catalytic cracking, steam cracking, coking, visbreaking unit, the first fraction representing between 30 and 70% by weight of the mixture, and
  • a second fraction comprising hydrocarbons having a boiling temperature range between 160°C and the final boiling temperature of the mixture, said second fraction comprising at least 10% by weight of hydrocarbons having a boiling temperature range between between 220°C and the final boiling temperature of the mixture, the second fraction being a light oil from a catalytic cracking unit,
the process comprising the following steps:
  1. a) said mixture consisting of said first fraction and said second fraction is treated in a first reactor in a first hydrodesulfurization step in the presence of hydrogen and a catalyst comprising at least one metal from group VIII, at least one metal of group VIB and a support, the content of metal(s) of group VIII being between 1.5 and 9% by weight of oxide(s) of metal(s) of group VIII and the content of metal(s) of the group VIB being between 4 and 40% by weight of oxide(s) of metal(s) of group VIB, the molar ratio metal(s) of group VIII to metal(s) of group VIB in the catalyst in oxide form is between 0.1 and 0.8, the first hydrodesulfurization step being carried out at a temperature between 200 and 400°C, at a pressure between 1 and 10 MPa, with a liquid space velocity between 0.1 and 10 h -1 and with a ratio (volume of hydrogen / volume of hydrocarbon mixture) of between 50 and 500 Nliter/liter;
  2. b) the hydrogen sulphide is removed from the partially desulphurized effluent resulting from step a);
  3. c) the partially desulfurized mixture resulting from step b) is treated in a second reactor in a second hydrodesulfurization step in the presence of hydrogen and a catalyst comprising at least one element from group VIII, at least one element from group VIII, group VIB and a support, the content of metal(s) of group VIII being between 0.5 and 15% by weight of oxide(s) of metal(s) of group VIII and the content of metal(s) of group VIB being between 1.5 and 60% by weight of metal oxide(s) from group VIB, the second hydrodesulphurization step being carried out at a temperature between 205 and 500°C, at a pressure between 1 and 3 MPa, with a liquid space velocity between 1 and 10 h -1 and with a ratio (volume of hydrogen / volume of mixture) between 50 and 500 Nliter/liter, the temperature of the second hydrodesulfurization stage c) being greater than that of the first hydrodesulfurization step a); And
  4. d) the desulfurized mixture resulting from step c) is fractionated into at least two desulfurized light and heavy hydrocarbon cuts, the light hydrocarbon cut having an initial boiling temperature of between 35°C and 100°C and a final boiling temperature of between 160°C and 220°C and whose total sulfur content is less than 50 ppm by weight and the heavy hydrocarbon cut having an initial boiling temperature of between 160°C and 220° C and a final boiling temperature of between 260°C and 340°C.

Dans le contexte de l'invention, les températures d'ébullition peuvent fluctuer à plus ou moins 5°C par rapport aux valeurs mentionnées.In the context of the invention, the boiling temperatures can fluctuate by plus or minus 5°C compared to the values mentioned.

Les inventeurs ont observé de façon surprenante qu'il est possible d'hydrodésulfurer de manière conjointe un mélange contenant une coupe essence et une coupe de distillat chargée en soufre et à basse teneur en oléfines afin de produire une coupe essence à basse teneur en soufre, en particulier en mercaptans, sans perte significative de l'indice d'octane et une coupe de distillat appauvrie en soufre qui peut être ensuite valorisée au pool diesel et/ou kérosène ou comme combustible à usage maritime.The inventors have surprisingly observed that it is possible to jointly hydrodesulfurize a mixture containing a gasoline cut and a distillate cut loaded with sulfur and with a low olefin content in order to produce a gasoline cut with a low sulfur content, in particular in mercaptans, without significant loss of octane number and a cut of distillate depleted in sulfur which can then be upgraded to the diesel and/or kerosene pool or as fuel for maritime use.

En particulier le traitement dans la première étape d'hydrodésulfuration du mélange d'hydrocarbures conduit de façon surprenante à limiter la formation de mercaptans de recombinaison, produits de réaction de l'addition de l'H2S avec les oléfines, et à obtenir ainsi à l'issue du procédé une coupe essence ayant une teneur très faible en mercaptans. La seconde étape d'hydrodésulfuration est réalisée dans des conditions qui favorisent ensuite l'hydroconversion des composés soufrés plus réfractaires qui proviennent essentiellement de la coupe de distillat.In particular, the treatment in the first hydrodesulfurization step of the hydrocarbon mixture leads surprisingly to limit the formation of recombinant mercaptans, reaction products of the addition of H 2 S with the olefins, and thus to obtain at the end of the process a gasoline cut having a very low mercaptan content. The second hydrodesulfurization step is carried out under conditions which then favor the hydroconversion of the more refractory sulfur compounds which essentially come from the distillate cut.

Le procédé selon l'invention répond bien au problème de surcapacités des unités d'hydrodésulfuration des essences dans la mesure où ces mêmes unités peuvent maintenant servir à désulfurer conjointement des coupes essences et des coupes de distillat moyen qui sont des bases pour la formulation des carburants diesel et/ou kérosène ou utilisables comme combustibles à usage maritime à basse teneur en soufre.The process according to the invention responds well to the problem of overcapacity of gasoline hydrodesulphurization units to the extent that these same units can now be used to jointly desulphurize gasoline cuts and middle distillate cuts which are bases for the formulation of fuels. diesel and/or kerosene or usable as fuels for maritime use with low sulfur content.

Description détaillée de l'inventionDetailed description of the invention

L'invention concerne donc un procédé mettant en oeuvre au moins deux étapes d'hydrodésulfuration successives d'un mélange d'hydrocarbures constitué d'une première et d'une seconde fractions d'hydrocarbures avec une étape intermédiaire d'élimination du sulfure d'hydrogène (H2S) formé dans la première étape d'hydrodésulfuration et avec une température de réaction dans la seconde étape d'hydrodésulfuration qui est supérieure à celle de la première étape d'hydrodésulfuration.The invention therefore relates to a process implementing at least two successive hydrodesulphurization stages of a mixture of hydrocarbons consisting of a first and a second hydrocarbon fraction with an intermediate stage of elimination of the hydrogen sulfide (H 2 S) formed in the first hydrodesulfurization step and with a reaction temperature in the second hydrodesulfurization step which is higher than that in the first hydrodesulfurization step.

Dans un mode de réalisation préféré, le catalyseur de l'étape a) est un catalyseur d'hydrodésulfuration qui comprend un métal du groupe VIII choisi parmi le nickel et le cobalt et un métal du groupe VIB choisi parmi le molybdène et le tungstène.In a preferred embodiment, the catalyst of step a) is a hydrodesulfurization catalyst which comprises a Group VIII metal chosen from nickel and cobalt and a Group VIB metal chosen from molybdenum and tungsten.

De préférence le catalyseur de l'étape c) est également un catalyseur d'hydrodésulfuration qui comprend un métal du groupe VIII choisi parmi le nickel et le cobalt et un métal du groupe VIB choisi parmi le molybdène et le tungstène.Preferably the catalyst of step c) is also a hydrodesulfurization catalyst which comprises a metal from group VIII chosen from nickel and cobalt and a metal from group VIB chosen from molybdenum and tungsten.

La première fraction d'hydrocarbures contenant des oléfines est une coupe essence oléfinique issue d'une unité de craquage catalytique, de vapocraquage, de cokéfaction, de viscoréduction.The first fraction of hydrocarbons containing olefins is an olefinic gasoline cut from a catalytic cracking, steam cracking, coking, visbreaking unit.

La seconde fraction d'hydrocarbures du mélange traité par le procédé selon l'invention est une coupe d'huile légère issue d'une unité de craquage catalytique (LCO ou "Light Cycle Oil" selon la terminologie anglo-saxonne).The second hydrocarbon fraction of the mixture treated by the process according to the invention is a light oil cut from a catalytic cracking unit (LCO or "Light Cycle Oil" according to Anglo-Saxon terminology).

La charge du procédé selon l'invention est un mélange contenant une coupe essence de craquage catlaytique et une coupe d'huile légère LCO. De manière avantageuse, ledit mélange est le produit d'une distillation d'un effluent issu d'une unité de craquage catalytique.The feed for the process according to the invention is a mixture containing a catlaytic cracked gasoline cut and an LCO light oil cut. Advantageously, said mixture is the product of a distillation of an effluent from a catalytic cracking unit.

La fraction légère du LCO, i.e. les composés ayant un point d'ébullition inférieur à 300°C, et de manière très préférée inférieur à 265°C est utilisé en mélange avec l'essence de craquage catalytique.The light fraction of the LCO, i.e. the compounds having a boiling point lower than 300°C, and very preferably lower than 265°C, is used in mixture with the catalytic cracking gasoline.

La première fraction ou coupe d'hydrocarbures représente entre 30 et 70% poids du mélange.The first fraction or hydrocarbon cut represents between 30 and 70% by weight of the mixture.

Selon un mode de réalisation alternatif, la première fraction du mélange est une fraction lourde d'une essence de craquage catalytique et la seconde fraction est une coupe d'huile légère LCO. La fraction lourde de l'essence de craquage catalytique est obtenue par distillation d'une coupe essence de craquage catalytique en deux fractions, une fraction légère C5- comprenant les hydrocarbures ayant un nombre d'atomes de carbone compris entre 2 et 5 atomes et une fraction lourde C6+ comprenant les hydrocarbures ayant un nombre d'atomes de carbone supérieur ou égal à 6.According to an alternative embodiment, the first fraction of the mixture is a heavy fraction of a catalytic cracked gasoline and the second fraction is a cut of light LCO oil. The heavy fraction of catalytically cracked gasoline is obtained by distillation of a catalytically cracked gasoline cut into two fractions, a light C5- fraction comprising hydrocarbons having a number of carbon atoms of between 2 and 5 atoms and a heavy C6+ fraction comprising hydrocarbons having a number of atoms of carbon greater than or equal to 6.

Dans un mode de réalisation très préféré, avant l'étape de séparation de la coupe essence de craquage catalytique en deux fractions, on traite ladite coupe essence dans une étape d'hydrogénation sélective des dioléfines.In a very preferred embodiment, before the step of separating the catalytically cracked gasoline cut into two fractions, said gasoline cut is treated in a step of selective hydrogenation of the diolefins.

D'autres caractéristiques et avantages de l'invention vont apparaître à la lecture de la description qui va suivre, donnée à titre uniquement illustratif et non limitatif, et à laquelle est annexée :

  • la figure 1 qui montre un schéma de principe du procédé selon l'invention.
Other characteristics and advantages of the invention will appear on reading the description which follows, given for illustrative and non-limiting purposes only, and to which is appended:
  • there figure 1 which shows a block diagram of the process according to the invention.

En référence à la figure 1, la première coupe d'hydrocarbures traitée par le procédé selon l'invention est envoyée par la conduite 1 vers un premier réacteur d'hydrodésulfuration 2. Cette première coupe d'hydrocarbures est combinée (mélangée) à une seconde coupe d'hydrocarbures apportée par la conduite 3. Le mélange, qui est constitué de deux fractions, est ensuite traité dans le premier réacteur d'hydrodésulfuration 2.In reference to the figure 1 , the first cut of hydrocarbons treated by the process according to the invention is sent via line 1 to a first hydrodesulphurization reactor 2. This first cut of hydrocarbons is combined (mixed) with a second cut of hydrocarbons supplied by line 3. The mixture, which is made up of two fractions, is then treated in the first hydrodesulfurization reactor 2.

La première coupe d'hydrocarbures, une coupe essence oléfinique issue d'une unité de craquage catalytique, de vapocraquage, de cokéfaction, de viscoréduction. De préférence, la coupe essence est une essence de craquage catalytique. Typiquement, la coupe essence a une température d'ébullition initiale comprise entre 35°C et 100°C et une température d'ébullition finale comprise entre 130 et 200°C, de préférence comprise entre 150 et 170°C et de manière plus préférée comprise entre 155 et 165°C. Généralement la teneur en oléfines de la première coupe (ou première fraction composant le mélange) est comprise entre 20 et 80% poids de ladite coupe.The first hydrocarbon cut, an olefinic gasoline cut from a catalytic cracking, steam cracking, coking, visbreaking unit. Preferably, the gasoline cut is a catalytic cracked gasoline. Typically, the gasoline cut has an initial boiling temperature of between 35°C and 100°C and a final boiling temperature of between 130 and 200°C, preferably between 150 and 170°C and more preferably between 155 and 165°C. Generally the olefin content of the first cut (or first fraction making up the mixture) is between 20 and 80% by weight of said cut.

La seconde coupe d'hydrocarbures a une température d'ébullition initiale d'environ 160°C et la température d'ébullition finale comprise entre 260 et 340°C et comprend une fraction d'au moins 10% poids d'hydrocarbures ayant une température d'ébullition comprise entre 220°C et sa température d'ébullition finale.The second hydrocarbon cut has an initial boiling temperature of approximately 160°C and the final boiling temperature of between 260 and 340°C and comprises a fraction of at least 10% by weight of hydrocarbons having a temperature boiling temperature between 220°C and its final boiling temperature.

Cette seconde coupe d'hydrocarbures est une coupe d'huile légère issue d'une unité de craquage catalytique (LCO ou "Light Cycle Oil" selon la terminologie anglo-saxonne).This second hydrocarbon cut is a light oil cut from a catalytic cracking unit (LCO or “Light Cycle Oil” according to Anglo-Saxon terminology).

Cette seconde coupe présente une teneur en oléfines inférieure à celle de la première coupe et une teneur en soufre total supérieure à celle de la première coupe.This second cut has an olefin content lower than that of the first cut and a total sulfur content higher than that of the first cut.

Ainsi le mélange d'hydrocarbures traité a une température d'ébullition initiale comprise entre 35°C et 100°C et une température d'ébullition finale comprise entre 260°C et 340°C et une teneur en soufre total comprise entre 30 et 10000 ppm poids. Le mélange traité est constitué de :

  • une première fraction comprenant des hydrocarbures ayant une gamme de températures d'ébullition comprise entre la température d'ébullition initiale du mélange et 160°C et dont la teneur en oléfines est comprise entre 20 et 80% poids de ladite première fraction, la première fraction étant choisie parmi une coupe essence oléfinique issue d'une unité de craquage catalytique, de vapocraquage, de cokéfaction, de viscoréduction, la première fraction représentant entre 30 et 70 % poids du mélange, et
  • une seconde fraction comprenant des hydrocarbures ayant une gamme de températures d'ébullition comprise entre 160°C et la température d'ébullition finale du mélange, la seconde fraction étant une huile légère issue d'une unité de craquage catalytique.
Thus the treated hydrocarbon mixture has an initial boiling temperature of between 35°C and 100°C and a final boiling temperature of between 260°C and 340°C and a total sulfur content of between 30 and 10,000. ppm weight. The treated mixture consists of:
  • a first fraction comprising hydrocarbons having a boiling temperature range between the initial boiling temperature of the mixture and 160°C and whose olefin content is between 20 and 80% by weight of said first fraction, the first fraction being chosen from an olefinic gasoline cut from a catalytic cracking, steam cracking, coking, visbreaking unit, the first fraction representing between 30 and 70% by weight of the mixture, and
  • a second fraction comprising hydrocarbons having a boiling temperature range between 160°C and the final boiling temperature of the mixture, the second fraction being a light oil from a catalytic cracking unit.

Selon l'invention, ladite seconde fraction comprend au moins 10% poids d'hydrocarbures ayant une gamme de températures d'ébullition comprise entre 220°C et la température d'ébullition finale du mélange.According to the invention, said second fraction comprises at least 10% by weight of hydrocarbons having a boiling temperature range between 220°C and the final boiling temperature of the mixture.

La première étape d'hydrodésulfuration permet de convertir une partie du soufre présent dans le mélange en sulfure d'hydrogène (H2S). Elle consiste à faire passer le mélange d'hydrocarbures à traiter en présence d'hydrogène (apporté par la conduite 4), sur un catalyseur d'hydrodésulfuration, à une température comprise entre 200°C et 400°C, de préférence entre 250°C et 340°C et à une pression comprise entre 1 et 10 MPa, de préférence entre 1,5 et 4 MPa. La vitesse spatiale liquide est généralement comprise entre 1 et 10 h-1, de préférence entre 2 et 5 h-1 et le rapport H2/HC est compris entre 50 Nlitres/litre (l/l) et 500 Nlitres/litre, de préférence entre 100 Nlitres/litre et 450 Nlitres/litre, et de façon plus préférée entre 150 Nlitres/litre et 400 Nlitres/litre. Le rapport H2/HC est le rapport entre le débit volumique d'hydrogène sous 1 atmosphère et à 0°C et le débit volumique d'hydrocarbures.The first hydrodesulfurization step converts part of the sulfur present in the mixture into hydrogen sulfide (H 2 S). It consists of passing the mixture of hydrocarbons to be treated in the presence of hydrogen (supplied via line 4), over a hydrodesulphurization catalyst, at a temperature between 200°C and 400°C, preferably between 250°C. C and 340°C and at a pressure of between 1 and 10 MPa, preferably between 1.5 and 4 MPa. The liquid space velocity is generally between 1 and 10 h -1 , preferably between 2 and 5 h -1 and the H 2 /HC ratio is between 50 Nliters/liter (l/l) and 500 Nliters/liter, preferably between 100 Nliters/liter and 450 Nliters/liter, and more preferably between 150 Nliters/liter and 400 Nliters/liter. The H 2 /HC ratio is the ratio between the volume flow rate of hydrogen under 1 atmosphere and at 0°C and the volume flow rate of hydrocarbons.

L'effluent issu de cette étape d'hydrodésulfuration soutiré par la ligne 5 comprend le mélange d'hydrocarbures partiellement désulfuré, l'hydrogène résiduel et l'H2S produit par décomposition des composés soufrés. Cette étape d'hydrodésulfuration est effectuée par exemple dans un réacteur en lit fixe ou en lit mobile.The effluent resulting from this hydrodesulfurization step withdrawn by line 5 comprises the mixture of partially desulfurized hydrocarbons, the residual hydrogen and the H 2 S produced by decomposition of sulfur compounds. This hydrodesulfurization step is carried out for example in a fixed bed or moving bed reactor.

Le catalyseur utilisé au cours de la première étape d'hydrodésulfuration du procédé d'hydrodésulfuration selon l'invention comprend une phase métallique active déposée sur un support, ladite phase active comprenant au moins un métal du groupe VIII de la classification périodique des éléments (groupes 8, 9 et 10 selon la nouvelle notation de la classification périodique des éléments : Handbook of Chemistry and Physics, 76ième édition, 1995-1996 ) et au moins un métal du groupe VIB de la classification périodique des éléments (groupe 6 selon la nouvelle notation de la classification périodique des éléments : Handbook of Chemistry and Physics, 76ième édition, 1995-1996 ). De manière préférée, la phase active dudit catalyseur comprend en outre du phosphore. Le catalyseur de la première étape d'hydrodésulfuration peut également en outre contenir un ou plusieurs composés organiques.The catalyst used during the first hydrodesulfurization step of the hydrodesulfurization process according to the invention comprises an active metal phase deposited on a support, said active phase comprising at least one metal from group VIII of the periodic table of elements (groups 8, 9 and 10 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ) and at least one metal from group VIB of the periodic table of elements (group 6 according to the new notation of the periodic table of elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ). Preferably, the active phase of said catalyst further comprises phosphorus. The catalyst of the first hydrodesulfurization step may also additionally contain one or more organic compounds.

De manière générale, la teneur en métal(ux) du groupe VIB dans ledit catalyseur de la première étape d'hydrodésulfuration est comprise entre 4 et 40% poids d'oxyde(s) de métal(ux) du groupe VIB, de manière préférée entre 8 et 35% poids d'oxyde(s) de métal(ux) du groupe VIB, de manière très préférée entre 10 et 30% poids d'oxyde(s) de métal(ux) du groupe VIB par rapport au poids total du catalyseur. De préférence, le métal du groupe VIB est le molybdène ou le tungstène ou un mélange de ces deux éléments, et de manière plus préférée le métal du groupe VIB est constitué uniquement de molybdène ou de tungstène. Le métal du groupe VIB est de manière très préférée le molybdène.Generally, the content of metal(s) from group VIB in said catalyst of the first hydrodesulfurization step is between 4 and 40% by weight of oxide(s) of metal(s) from group VIB, preferably between 8 and 35% by weight of metal oxide(s) from group VIB, very preferably between 10 and 30% by weight of metal oxide(s) from group VIB relative to the total weight of the catalyst. Preferably, the Group VIB metal is molybdenum or tungsten or a mixture of these two elements, and more preferably the Group VIB metal consists solely of molybdenum or tungsten. The Group VIB metal is most preferably molybdenum.

De manière générale, la teneur en métal(ux) du groupe VIII dans ledit catalyseur de la première étape d'hydrodésulfuration est comprise entre 1,5 et 9% poids d'oxyde(s) de métal(ux) du groupe VIII, de manière préférée comprise entre 2 et 8% poids d'oxyde(s) de métal(ux) du groupe VIII par rapport au poids total du catalyseur. De préférence, le métal du groupe VIII est un métal non noble du groupe VIII de la classification périodique des éléments. De manière très préférée, ledit métal du groupe VIII est le cobalt ou le nickel ou un mélange de ces deux éléments, et de manière plus préférée le métal du groupe VIII est constitué uniquement de cobalt ou de nickel. Le métal du groupe VIII est de manière très préférée le cobalt.In general, the content of metal(s) from Group VIII in said catalyst of the first hydrodesulfurization step is between 1.5 and 9% by weight of oxide(s) of metal(s) from Group VIII, of preferably between 2 and 8% by weight of oxide(s) of metal(s) from Group VIII relative to the total weight of the catalyst. Preferably, the group VIII metal is a non-noble metal from group VIII of the periodic table of elements. Very preferably, said Group VIII metal is cobalt or nickel or a mixture of these two elements, and more preferably the Group VIII metal consists solely of cobalt or nickel. The Group VIII metal is most preferably cobalt.

Le rapport molaire métal(ux) du groupe VIII sur métal(ux) du groupe VIB dans le catalyseur sous forme oxyde est compris entre 0,1 et 0,8, très préférentiellement compris entre 0,2 et 0,6, et de manière encore plus préférée compris entre 0,3 et 0,5.The molar ratio of metal(s) from group VIII to metal(s) from group VIB in the catalyst in oxide form is between 0.1 and 0.8, very preferably between 0.2 and 0.6, and so even more preferred between 0.3 and 0.5.

Lorsque le catalyseur contient du phosphore, la teneur en phosphore du catalyseur de la première étape d'hydrodésulfuration est de préférence comprise entre 0,1 et 20% poids de P2O5, de manière plus préférée entre 0,2 et 15% poids de P2O5, de manière très préférée entre 0,3 et 10% poids de P2O5 par rapport au poids total du catalyseur.When the catalyst contains phosphorus, the phosphorus content of the catalyst of the first hydrodesulfurization step is preferably between 0.1 and 20% by weight of P 2 O 5 , more preferably between 0.2 and 15% by weight of P 2 O 5 , very preferably between 0.3 and 10% by weight of P 2 O 5 relative to the total weight of the catalyst.

Le rapport molaire phosphore sur métal(ux) du groupe VIB dans le catalyseur de la première étape d'hydrodésulfuration est supérieur ou égal à 0,05, de préférence supérieur ou égal à 0,1, de manière plus préférée compris entre 0,15 et 0,6, de manière encore plus préférée compris entre 0,15 et 0,5.The molar ratio of phosphorus to metal(s) of group VIB in the catalyst of the first hydrodesulfurization step is greater than or equal to 0.05, preferably greater than or equal to 0.1, more preferably between 0.15 and 0.6, even more preferably between 0.15 and 0.5.

Le support du catalyseur de la première étape d'hydrodésulfuration sur lequel est déposée la phase active est avantageusement formé d'au moins un solide poreux sous forme oxyde choisi dans le groupe constitué par les alumines, les silices, les silices-alumine ou encore les oxydes de titane ou de magnésium utilisé(s) seul ou en mélange avec l'alumine ou la silice-alumine. Il est de préférence choisi dans le groupe constitué par les silices, les alumines de transition et les silices-alumine. De manière plus préférée, ledit support est constitué uniquement d'une alumine de transition ou d'un mélange d'alumines de transition. La surface spécifique du catalyseur est généralement comprise entre 100 et 400 m2/g, de préférence entre 150 et 300 m2/g. Le catalyseur de la première étape d'hydrodésulfuration se présente avantageusement sous forme de billes, d'extrudés, de pastilles, ou d'agglomérats irréguliers et non sphériques dont la forme spécifique peut résulter d'une étape de concassage. De manière très avantageuse, ledit support se présente sous forme de billes ou d'extrudés.The support of the catalyst of the first hydrodesulfurization step on which the active phase is deposited is advantageously formed of at least one porous solid in oxide form chosen from the group consisting of aluminas, silicas, silica-alumina or even titanium or magnesium oxides used alone or mixed with alumina or silica-alumina. It is preferably chosen from the group consisting of silicas, transition aluminas and silica-alumina. More preferably, said support consists solely of a transition alumina or of a mixture of transition aluminas. The specific surface area of the catalyst is generally between 100 and 400 m 2 /g, preferably between 150 and 300 m 2 /g. The catalyst of the first hydrodesulfurization step is advantageously in the form of beads, extrudates, pellets, or irregular and non-spherical agglomerates whose specific shape can result from a crushing step. Very advantageously, said support is in the form of balls or extrudates.

Le catalyseur de la première étape d'hydrodésulfuration est de préférence utilisé au moins en partie sous sa forme sulfurée. La sulfuration consiste à passer une charge contenant au moins un composé soufré, qui une fois décomposé conduit à la fixation de soufre sur le catalyseur. Cette charge peut être gazeuse ou liquide, par exemple de l'hydrogène contenant de l'H2S, ou un liquide contenant au moins un composé soufré. L'étape de sulfuration peut être réalisée in situ, c'est-à-dire au sein du procédé selon l'invention, ou ex situ, c'est à dire dans une unité dédiée aux sulfurations de catalyseurs.The catalyst of the first hydrodesulfurization step is preferably used at least partly in its sulfurized form. Sulfurization consists of passing a charge containing at least one sulfur compound, which once decomposed leads to the fixation of sulfur on the catalyst. This charge can be gaseous or liquid, for example hydrogen containing H 2 S, or a liquid containing at least one sulfur compound. The sulfurization step can be carried out in situ, that is to say within the process according to the invention, or ex situ, that is to say in a unit dedicated to the sulfurization of catalysts.

Selon l'invention, le procédé comprend une étape où l'H2S est au moins en partie éliminé de l'effluent obtenu à l'issu de la première étape d'hydrodésulfuration. Cette étape peut être réalisée au moyen de toutes techniques connues de l'homme du métier. Elle peut être réalisée directement dans les conditions dans lesquelles se trouve l'effluent à l'issue de cette étape ou après que les conditions aient été changées afin de faciliter l'élimination d'au moins une partie de l'H2S. Comme technique envisageable, on peut par exemple citer une séparation gaz/liquide (où le gaz se concentre en H2S et le liquide est appauvri en H2S), une étape de stripage l'effluent, une étape de lavage aux amines, une captation de l'H2S par une masse absorbante opérant sur l'effluent gazeux ou liquide, une séparation de l'H2S de l'effluent gazeux ou liquide par une membrane. Une combinaison de une ou plusieurs des possibilités présentées précédemment est aussi possible, comme par exemple une séparation gaz/liquide à la suite de laquelle l'effluent liquide est envoyé dans une colonne de stripage tandis que l'effluent gazeux est envoyé dans une étape de lavage aux amines.According to the invention, the process comprises a step where the H 2 S is at least partly eliminated from the effluent obtained at the end of the first hydrodesulfurization step. This step can be carried out using any techniques known to those skilled in the art. It can be carried out directly in the conditions in which the effluent is found at the end of this step or after the conditions have been changed in order to facilitate the elimination of at least part of the H 2 S. As possible technique, we can for example cite a gas/liquid separation (where the gas concentrates in H 2 S and the liquid is depleted in H 2 S), an effluent stripping step, an amine washing step, a capture of H 2 S by an absorbent mass operating on the gaseous or liquid effluent, separation of H 2 S from the gaseous or liquid effluent through a membrane. A combination of one or more of the possibilities presented previously is also possible, such as for example a gas/liquid separation following which the liquid effluent is sent to a stripping column while the gaseous effluent is sent to a stage of amine wash.

En référence à la figure 1, l'effluent issu du réacteur de la première étape d'hydrodésulfuration est envoyé via la conduite 5 dans une colonne de stripage 6 qui permet de séparer en tête de la colonne un flux gazeux 7 contenant de l'hydrogène et de l'H2S et en fond un effluent contenant un mélange d'hydrocarbures 8 partiellement désulfuré et débarrassé de l'H2S.In reference to the figure 1 , the effluent from the reactor of the first hydrodesulphurization stage is sent via line 5 to a stripping column 6 which makes it possible to separate at the top of the column a gaseous flow 7 containing hydrogen and H 2 S and at the bottom an effluent containing a mixture of hydrocarbons 8 partially desulfurized and freed of H 2 S.

De manière surprenante, les inventeurs ont trouvé que la présence d'une coupe de distillat en mélange avec une coupe essence a un effet positif sur la réduction de la formation de mercaptans de recombinaison dans l'effluent partiellement désulfuré.Surprisingly, the inventors have found that the presence of a distillate cut mixed with a gasoline cut has a positive effect on reducing the formation of recombination mercaptans in the partially desulfurized effluent.

Généralement, à l'issue de l'étape de séparation de l'H2S, on obtient un mélange d'hydrocarbures ayant une teneur en soufre totale comprise entre 100 et 1000 ppm poids, de préférence comprise entre 200 et 500 ppm poids.Generally, at the end of the H 2 S separation step, a mixture of hydrocarbons is obtained having a total sulfur content of between 100 and 1000 ppm by weight, preferably between 200 and 500 ppm by weight.

En référence à la figure 1, l'effluent comprenant le mélange d'hydrocarbures partiellement désulfuré est traité dans une étape supplémentaire d'hydrodésulfuration (HDS) visant à améliorer le taux de désulfuration final. Cette seconde étape a pour but de transformer les composés soufré réfractaires présents dans le mélange et qui sont essentiellement apportés par la seconde coupe mise en oeuvre dans le procédé selon l'invention. A cette fin, l'effluent est envoyé par la ligne 8 dans un réacteur d'hydrodésulfuration 9 et est mis en contact avec un catalyseur d'hydrodésulfuration en présence d'hydrogène apporté par la ligne 10.In reference to the figure 1 , the effluent comprising the partially desulfurized hydrocarbon mixture is treated in an additional hydrodesulfurization step (HDS) aimed at improving the final desulfurization rate. This second step aims to transform the refractory sulfur compounds present in the mixture and which are essentially provided by the second cut implemented in the process according to the invention. To this end, the effluent is sent via line 8 to a hydrodesulfurization reactor 9 and is brought into contact with a hydrodesulfurization catalyst in the presence of hydrogen supplied by line 10.

Les conditions opératoires pour la seconde étape d'hydrodésulfuration sont les suivantes:

  • une température comprise entre 205°C et 500°C, de préférence entre 250°C et 320°C ;
  • une pression comprise entre 1 et 3 MPa, de préférence entre 1,5 et 2,5 MPa
  • une vitesse spatiale liquide est généralement comprise entre 1 et 10 h-1, de préférence entre 2 et 5 h-1,
  • un rapport H2/HC est compris entre 50 Nlitres/litre (l/l) et 500 Nlitres/litre, de préférence entre 100 Nlitres/litre et 450 Nlitres/litre, et de façon plus préférée entre 150 Nlitres/litre et 400 Nlitres/litre. Le rapport H2/HC est le rapport entre le débit d'hydrogène sous 1 atmosphère et à 0°C et le débit d'hydrocarbures.
The operating conditions for the second hydrodesulfurization step are as follows:
  • a temperature between 205°C and 500°C, preferably between 250°C and 320°C;
  • a pressure between 1 and 3 MPa, preferably between 1.5 and 2.5 MPa
  • a liquid space velocity is generally between 1 and 10 h -1 , preferably between 2 and 5 h -1 ,
  • an H 2 /HC ratio is between 50 Nliters/liter (l/l) and 500 Nliters/liter, preferably between 100 Nliters/liter and 450 Nliters/liter, and more preferably between 150 Nliters/liter and 400 Nliters /liter. The H 2 /HC ratio is the ratio between the hydrogen flow rate under 1 atmosphere and at 0°C and the hydrocarbon flow rate.

Selon l'invention, la température de la seconde étape d'HDS est supérieure à celle de la première étape d'HDS, de préférence supérieure d'au moins 5°C et de manière encore plus préférée d'au moins 10°C. De façon avantageuse, la seconde étape d'hydrodésulfuration met en oeuvre un catalyseur ayant une sélectivité en hydrodésulfuration par rapport à l'hydrogénation des oléfines supérieure au catalyseur de la première étape d'hydrodésulfuration.According to the invention, the temperature of the second HDS stage is higher than that of the first HDS stage, preferably higher by at least 5°C and even more preferably by at least 10°C. Advantageously, the second hydrodesulfurization step uses a catalyst having a selectivity in hydrodesulfurization with respect to the hydrogenation of olefins greater than the catalyst of the first hydrodesulfurization step.

Le catalyseur adapté pour cette seconde étape d'hydrodésulfuration comprend au moins un métal du groupe VIII (groupes 8, 9 et 10 selon la nouvelle notation de la classification périodique des éléments : Handbook of Chemistry and Physics, 76ième édition, 1995-1996 ) et au moins un métal du groupe VIB (groupe 6 selon la nouvelle notation de la classification périodique des éléments : Handbook of Chemistry and Physics, 76ième édition, 1995-1996 ) sur un support approprié.The catalyst suitable for this second hydrodesulfurization step comprises at least one metal from group VIII (groups 8, 9 and 10 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ) and at least one metal from group VIB (group 6 according to the new notation of the periodic classification of the elements: Handbook of Chemistry and Physics, 76th edition, 1995-1996 ) on an appropriate support.

La teneur en métal du groupe VIII exprimée en oxyde est généralement comprise entre 0,5 et 15 % poids, préférentiellement entre 1 et 10% poids par rapport au poids total de catalyseur.The Group VIII metal content expressed as oxide is generally between 0.5 and 15% by weight, preferably between 1 and 10% by weight relative to the total weight of catalyst.

La teneur en métal du groupe VIB est généralement comprise entre 1,5 et 60% poids, préférentiellement entre 3 et 50% poids par apport au poids total de catalyseur.The metal content of group VIB is generally between 1.5 and 60% by weight, preferably between 3 and 50% by weight per contribution to the total weight of catalyst.

Le métal du groupe VIII est de préférence le cobalt et le métal du groupe VIB est généralement le molybdène ou le tungstène.The Group VIII metal is preferably cobalt and the Group VIB metal is generally molybdenum or tungsten.

De manière préférée, le catalyseur de la seconde étape d'hydrodésulfuration comprend en outre du phosphore. La teneur en phosphore dudit catalyseur est de préférence comprise entre 0,1 et 20% poids de P2O5, de manière plus préférée entre 0,2 et 15% poids de P2O5, de manière très préférée entre 0,3 et 10% poids de P2O5 par rapport au poids total du catalyseur.Preferably, the catalyst for the second hydrodesulfurization step further comprises phosphorus. The phosphorus content of said catalyst is preferably between 0.1 and 20% by weight of P 2 O 5 , more preferably between 0.2 and 15% by weight of P 2 O 5 , very preferably between 0.3 and 10% by weight of P 2 O 5 relative to the total weight of the catalyst.

De manière préférée, le catalyseur comprend en outre un ou plusieurs composés organiques.Preferably, the catalyst further comprises one or more organic compounds.

Le support du catalyseur est habituellement un solide poreux, tel que par exemple une alumine, une silice-alumine ou d'autres solides poreux, tels que par exemple de la magnésie, de la silice ou de l'oxyde de titane, seuls ou en mélange avec de l'alumine ou de la silice-alumine.The catalyst support is usually a porous solid, such as for example alumina, silica-alumina or other porous solids, such as for example magnesia, silica or titanium oxide, alone or in combination. mixture with alumina or silica-alumina.

Pour minimiser l'hydrogénation des oléfines présentes dans l'essence lourde il est avantageux d'utiliser préférentiellement un catalyseur dans lequel la densité de molybdène, exprimée en % poids de MoOs par unité de surface de catalyseur, est supérieure à 0,07 et de préférence supérieure à 0,10. Le catalyseur selon l'invention présente, de préférence, une surface spécifique inférieure à 200 m2/g, de manière plus préférée inférieure à 180 m2/g, et de manière très préférée inférieure à 150 m2/g.To minimize the hydrogenation of the olefins present in heavy gasoline, it is advantageous to preferably use a catalyst in which the density of molybdenum, expressed in weight% of MoOs per unit surface area of catalyst, is greater than 0.07 and preferably greater than 0.10. The catalyst according to the invention preferably has a specific surface area less than 200 m 2 /g, more preferably less than 180 m 2 /g, and very preferably less than 150 m 2 /g.

Dans un mode de réalisation préféré, le catalyseur sélectif de la seconde étape d'hydrodésulfuration comprend du cobalt, du molybdène et éventuellement du phosphore déposés sur un support alumine et ayant les teneurs suivantes:

  • CoO comprise entre 1 et 6% poids par rapport au poids total de catalyseur;
  • MoOs comprise entre 3 et 15% poids par rapport au poids total de catalyseur;
  • P2O5 comprise entre 0 et 3 % poids par rapport au poids total de catalyseur;
  • une surface spécifique de catalyseur inférieure à 150 m2/g, de préférence comprise entre 50 et 150 m2/g.
In a preferred embodiment, the selective catalyst for the second hydrodesulfurization step comprises cobalt, molybdenum and optionally phosphorus deposited on an alumina support and having the following contents:
  • CoO between 1 and 6% by weight relative to the total weight of catalyst;
  • MoOs between 3 and 15% by weight relative to the total weight of catalyst;
  • P 2 O 5 between 0 and 3% by weight relative to the total weight of catalyst;
  • a specific catalyst surface area of less than 150 m 2 /g, preferably between 50 and 150 m 2 /g.

Le catalyseur de la seconde étape d'hydrodésulfuration est de préférence utilisé au moins en partie sous sa forme sulfurée. La sulfuration consiste à passer la charge contenant au moins un composé soufré, qui une fois décomposé conduit à la fixation de soufre sur le catalyseur. Cette charge peut être gazeuse ou liquide, par exemple de l'hydrogène contenant de l'H2S, ou un liquide contenant au moins un composé soufré. L'étape de sulfuration peut être réalisée in situ, c'est-à-dire au sein du procédé selon l'invention, ou ex situ, c'est à dire dans une unité dédiée aux sulfurations de catalyseurs.The catalyst of the second hydrodesulfurization step is preferably used at least partly in its sulfurized form. Sulfurization consists of passing the charge containing at least one sulfur compound, which once decomposed leads to the fixation of sulfur on the catalyst. This charge can be gaseous or liquid, for example hydrogen containing H 2 S, or a liquid containing at least one sulfur compound. The sulfurization step can be carried out in situ, that is to say within the process according to the invention, or ex situ, that is to say in a unit dedicated to the sulfurization of catalysts.

Après la seconde étape d'hydrodésulfuration, l'effluent désulfuré a une teneur en soufre total généralement inférieure à 50 ppm poids, de préférence inférieure à 30 ppm poids et présente une teneur en mercaptans généralement inférieure à 10 ppm poids.After the second hydrodesulfurization step, the desulfurized effluent has a total sulfur content generally less than 50 ppm by weight, preferably less than 30 ppm by weight and has a mercaptan content generally less than 10 ppm by weight.

Conformément à l'invention et comme représenté à la figure 1, l'effluent qui est soutiré du second réacteur d'hydrodésulfuration 9 est envoyé par la ligne 11 vers une unité de séparation 12. De manière préférée, avant d'être séparé, l'effluent du réacteur est d'abord envoyé vers un ballon de séparation gaz/liquide permettant de séparer un gaz riche en H2S de l'effluent liquide. Cet effluent liquide est ensuite envoyé dans une colonne de stabilisation afin d'éliminer les dernières traces d'H2S solubilisées et produire un produit de fond de colonne stabilisé, c'est-à-dire dont la pression de vapeur a été corrigée par élimination des composés hydrocarbures les plus légers. Les étapes de séparation gaz/liquide et de stabilisation sont des étapes classiques pour l'homme de l'art et ne sont pas représentées sur la figure 1.In accordance with the invention and as shown in figure 1 , the effluent which is withdrawn from the second hydrodesulfurization reactor 9 is sent via line 11 to a separation unit 12. Preferably, before being separated, the effluent from the reactor is first sent to a balloon gas/liquid separation allowing the separation of a gas rich in H 2 S from the liquid effluent. This liquid effluent is then sent to a stabilization column in order to eliminate the last traces of solubilized H 2 S and produce a stabilized column bottom product, that is to say whose vapor pressure has been corrected by elimination of the lightest hydrocarbon compounds. The gas/liquid separation and stabilization steps are classic steps for those skilled in the art and are not shown on the figure 1 .

L'étape de séparation ou de distillation consiste à séparer l'effluent stabilisé contenant le mélange d'hydrocarbures en au moins deux coupes d'hydrocarbures à savoir une coupe d'hydrocarbures légère et une coupe d'hydrocarbures lourde toutes deux désulfurées. De manière préférée, le point de coupe est généralement compris entre 160°C et 220°C, bornes incluses. En référence la figure 1, l'unité de séparation mise en oeuvre est une colonne de distillation configurée pour séparer en tête de la colonne une coupe légère désulfurée 13, équivalente à une coupe essence et en fond une coupe lourde désulfurée 14 équivalente à une coupe de distillat. La coupe essence est envoyée au pool essence et la coupe de distillat désulfurée est envoyée au pool diesel, kérosène ou fioul.The separation or distillation step consists of separating the stabilized effluent containing the mixture of hydrocarbons into at least two hydrocarbon cuts, namely a cut light hydrocarbons and a heavy hydrocarbon cut both desulfurized. Preferably, the cutting point is generally between 160°C and 220°C, limits included. In reference to the figure 1 , the separation unit used is a distillation column configured to separate at the top of the column a light desulphurized cut 13, equivalent to a gasoline cut and at the bottom a heavy desulphurized cut 14 equivalent to a distillate cut. The gasoline cut is sent to the gasoline pool and the desulfurized distillate cut is sent to the diesel, kerosene or fuel oil pool.

De préférence, la teneur en soufre dans la coupe légère (ou coupe essence) désulfurée est inférieure à 50 ppm poids, de manière préférée, inférieure à 30 ppm poids et de manière encore plus préférée inférieure à 10 ppm poids. De préférence, la teneur en soufre dans la coupe lourde (ou coupe de distillat) désulfurée est inférieure à 50 ppm poids, éventuellement inférieure à 30 ppm poids voire inférieure à 10 ppm poids.Preferably, the sulfur content in the desulfurized light cut (or gasoline cut) is less than 50 ppm by weight, preferably less than 30 ppm by weight and even more preferably less than 10 ppm by weight. Preferably, the sulfur content in the desulfurized heavy cut (or distillate cut) is less than 50 ppm by weight, optionally less than 30 ppm by weight or even less than 10 ppm by weight.

Il est également possible de réaliser la stabilisation et la distillation de manière concomitante dans une colonne à soutirage latéral et reflux externe total. La coupe de distillat est récupérée en fond, la coupe essence est soutirée latéralement plusieurs plateaux en dessous du plateau de tête tandis que les composés les plus légers sont éliminés en tête de colonne dans l'effluent gazeux.It is also possible to carry out stabilization and distillation concomitantly in a column with side withdrawal and total external reflux. The distillate cut is recovered at the bottom, the gasoline cut is withdrawn laterally several trays below the top tray while the lightest compounds are eliminated at the top of the column in the gaseous effluent.

De manière alternative, l'effluent issu de la colonne de stabilisation contenant le mélange d'hydrocarbures désulfuré est séparé en trois coupes. Dans ce cas, les deux points de coupe seront généralement à environ 160°C et à environ 220°C. Les trois coupes d'hydrocarbures présentent une teneur en soufre total inférieure à 50 ppm poids, de manière préférée, inférieure à 30 ppm poids et de manière encore plus préférée inférieure à 10 ppm poids.Alternatively, the effluent from the stabilization column containing the desulfurized hydrocarbon mixture is separated into three cuts. In this case, the two cutting points will generally be around 160°C and around 220°C. The three hydrocarbon cuts have a total sulfur content of less than 50 ppm by weight, preferably less than 30 ppm by weight and even more preferably less than 10 ppm by weight.

De façon surprenante, les inventeurs ont trouvé que la mise en oeuvre de deux étapes successivement d'hydrodésulfuration avec une étape intermédiaire d'élimination de l'H2S sur un mélange d'une coupe essence et de distillat moyen permet in fine de fournir une essence désulfurée avec une basse teneur en mercaptans et sans perte notable de l'indice d'octane et cela sans requérir à des conditions d'hydrodésulfuration particulièrement sévères qui s'accompagnent généralement d'une hydrogénation non négligeable des composés hydrocarbures mono-oléfiniques. En effet il est connu que la perte d'octane liée à l'hydrogénation des mono-oléfines lors des étapes d'hydrodésulfuration est d'autant plus grande que la teneur en soufre visée est basse, c'est à dire que lorsque l'on cherche à éliminer en profondeur les composés soufrés présents dans la charge.Surprisingly, the inventors have found that the implementation of two successive stages of hydrodesulfurization with an intermediate stage of elimination of H 2 S on a mixture of a gasoline cut and middle distillate ultimately makes it possible to provide a desulphurized gasoline with a low mercaptan content and without significant loss of octane number and this without requiring particularly severe hydrodesulphurization conditions which are generally accompanied by significant hydrogenation of the mono-olefinic hydrocarbon compounds. Indeed it is known that the loss of octane linked to the hydrogenation of mono-olefins during the hydrodesulfurization stages is all the greater as the targeted sulfur content is low, that is to say when the we seek to thoroughly eliminate the sulfur compounds present in the load.

Selon un mode de réalisation alternatif du procédé selon l'invention également représenté à la figure 1, une première coupe d'hydrocarbures du type essence est envoyée dans un réacteur de prétraitement 15 avant d'être mélangée avec une seconde coupe d'hydrocarbures. Comme indiqué plus haut, la charge d'hydrocarbures est de préférence une coupe essence de craquage catalytique qui contient généralement des dioléfines à une teneur comprise entre 0,1 et 3% poids). Le prétraitement consiste en une étape d'hydrogénation sélective des dioléfines en mono-oléfines correspondantes, qui est mise en oeuvre en présence d'un catalyseur et d'hydrogène. Le catalyseur d'hydrogénation sélective des dioléfines adapté pour le prétraitement comprend au moins un métal du groupe VIB et au moins un métal du groupe VIII déposés sur un support poreux décrits dans les demande de brevet FR 2 988 732 et EP 2 161 076 de la demanderesse. La réaction catalytique d'hydrogénation sélective est généralement conduite en présence d'hydrogène, à une température comprise entre 80°C et 220°C, et de préférence entre 90°C et 200°C, avec une vitesse spatiale liquide (LHSV) comprise entre 1 et 10 h-1, l'unité de la vitesse spatiale liquide étant le litre de charge par litre de catalyseur et par heure (l/l.h). La pression opératoire est comprise entre 0,5 MPa et 5 MPa, de préférence comprise entre 1 et 4 MPa.According to an alternative embodiment of the method according to the invention also represented in figure 1 , a first cut of gasoline type hydrocarbons is sent to a pretreatment reactor 15 before being mixed with a second cut of hydrocarbons. As indicated above, the hydrocarbon feedstock is preferably a catalytically cracked gasoline cut which generally contains diolefins at a content of between 0.1 and 3% by weight. The pretreatment consists of a step of selective hydrogenation of the diolefins into corresponding mono-olefins, which is carried out in the presence of a catalyst and hydrogen. The catalyst for selective hydrogenation of diolefins suitable for pretreatment comprises at least one metal from group VIB and at least one metal from group VIII deposited on a porous support described in the patent applications FR 2 988 732 And EP 2 161 076 of the plaintiff. The catalytic selective hydrogenation reaction is generally carried out in the presence of hydrogen, at a temperature between 80°C and 220°C, and preferably between 90°C and 200°C, with a liquid space velocity (LHSV) comprised between 1 and 10 h -1 , the unit of liquid space velocity being the liter of charge per liter of catalyst and per hour (l/lh). The operating pressure is between 0.5 MPa and 5 MPa, preferably between 1 and 4 MPa.

Généralement, l'essence produite contient moins de 0,5% poids de dioléfines, et de préférence moins de 0,25% poids de dioléfines.Generally, the gasoline produced contains less than 0.5% by weight of diolefins, and preferably less than 0.25% by weight of diolefins.

De façon avantageuse et comme indiquée sur la figure 1, la première coupe d'hydrocarbures prétraitée est dirigée via la ligne 16 vers une colonne de séparation 17 (splitter selon la terminologie anglo-saxonne) qui est conçue pour fractionner ladite charge prétraitée respectivement en une fraction légère C5- et une fraction lourde C6+. La fraction légère est avantageusement envoyée au pool essence par la ligne 18, alors que la fraction lourde C6+ rentrant dans la ligne 1 est hydrodésulfurée par le procédé décrit plus haut, c'est-à-dire en mélange avec une coupe de distillat moyen à faible teneur en oléfines.Advantageously and as indicated on the figure 1 , the first pretreated hydrocarbon cut is directed via line 16 to a separation column 17 (splitter according to Anglo-Saxon terminology) which is designed to split said pretreated charge respectively into a light fraction C5 - and a heavy fraction C6+. The light fraction is advantageously sent to the gasoline pool via line 18, while the heavy C6+ fraction entering line 1 is hydrodesulfurized by the process described above, that is to say mixed with a cut of middle distillate at low olefin content.

ExemplesExamples Exemple 1 (comparatif)Example 1 (comparative)

Un catalyseur α d'hydrodésulfuration est obtenu par imprégnation « sans excès de solution » d'une alumine de transition se présentant sous forme de billes de surface spécifique de 130 m2/g et de volume poreux 0,9 ml/g, par une solution aqueuse contenant du molybdène et du cobalt sous forme d'heptamolybdate d'ammonium et de nitrate de cobalt. Le catalyseur est ensuite séché et calciné sous air à 500°C. La teneur en cobalt et en molybdène du catalyseur α est de 3% poids de CoO et 10% poids de MoOs.An α hydrodesulfurization catalyst is obtained by impregnation “without excess solution” of a transition alumina in the form of beads with a specific surface area of 130 m 2 /g and a pore volume of 0.9 ml/g, by a aqueous solution containing molybdenum and cobalt in the form of ammonium heptamolybdate and cobalt nitrate. The catalyst is then dried and calcined in air at 500°C. The cobalt and molybdenum content of the α catalyst is 3% by weight of CoO and 10% by weight of MoOs.

50 ml du catalyseur α sont placés dans un réacteur d'hydrodésulfuration tubulaire à lit fixe. Le catalyseur est tout d'abord sulfuré par traitement pendant 4 heures sous une pression de 3,4 MPa à 350°C, au contact d'une charge constituée de 2% poids de soufre sous forme de diméthyldisulfure dans du n-heptane.50 ml of the α catalyst are placed in a tubular fixed-bed hydrodesulfurization reactor. The catalyst is first sulfurized by treatment for 4 hours under a pressure of 3.4 MPa at 350°C, in contact with a charge consisting of 2% by weight of sulfur in the form of dimethyldisulfide in n-heptane.

La charge traitée C est une essence de craquage catalytique dont le point initial d'ébullition est de 61°C et le point final de 162°C. Sa teneur en soufre est de 765 ppm poids et son indice de brome (IBr) est de 75,9 g/100 g ce qui correspond approximativement à 42% poids d'oléfines.The treated feed C is a catalytic cracked gasoline whose initial boiling point is 61°C and the final point is 162°C. Its sulfur content is 765 ppm by weight and its bromine index (IBr) is 75.9 g/100 g, which corresponds approximately to 42% by weight of olefins.

Cette charge C est traitée avec le catalyseur α, sous une pression de 2 MPa, un rapport volumique hydrogène sur charge à traiter (H2/HC) de 300 NI/l et une VVH de 4 h-1 . Après traitement, l'effluent est refroidi et l'hydrogène riche en H2S est séparé de l'essence liquide, et l'essence est soumise à un traitement de stripage par injection d'un flux d'hydrogène afin d'éliminer les traces résiduelles d'H2S dissous dans l'essence désulfurée.This charge C is treated with the catalyst α, under a pressure of 2 MPa, a volume ratio of hydrogen to charge to be treated (H 2 /HC) of 300 NI/l and a VVH of 4 h -1 . After treatment, the effluent is cooled and the hydrogen rich in H 2 S is separated from the liquid gasoline, and the gasoline is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate the residual traces of H 2 S dissolved in the desulfurized gasoline.

Le tableau 1 montre l'influence de la température mise en jeu sur les taux de désulfuration et l'indice RON des effluents désulfurés. Tableau 1 Analyse de l'essence désulfurée Température dans le réacteur d'hydrodésulfuration, 285 °C Température dans le réacteur d'hydrodésulfuration, 295 °C Mercaptans, ppm poids 16 7 Soufre total, ppm poids 25 12 Taux de désulfuration, % 96,7 98,4 Perte RON 6,9 8,4 Table 1 shows the influence of the temperature involved on the desulfurization rates and the RON index of the desulfurized effluents. Table 1 Analysis of desulfurized gasoline Temperature in the hydrodesulfurization reactor, 285 °C Temperature in the hydrodesulfurization reactor, 295 °C Mercaptans, ppm weight 16 7 Total sulfur, ppm weight 25 12 Desulfurization rate, % 96.7 98.4 RON loss 6.9 8.4

On constate que lorsque la température mise en oeuvre augmente, le taux de désulfuration est amélioré mais au prix d'une augmentation du taux d'hydrogénation des oléfines.It is noted that when the temperature used increases, the rate of desulfurization is improved but at the cost of an increase in the rate of hydrogenation of the olefins.

Exemple 2 (comparatif)Example 2 (comparative)

50 ml d'un catalyseur β d'hydrodésulfuration se présentant sous forme de extrudés de surface spécifique de 180 m2/g dont la teneur (poids d'oxyde(s) par rapport au poids total du catalyseur) en cobalt, molybdène et phosphore sont respectivement de 4,4% poids de CoO et 21,3% poids de MoO3 et 6,0% poids de P2O5 sont placés dans un réacteur d'hydrodésulfuration tubulaire à lit fixe. Le catalyseur est tout d'abord sulfuré par traitement pendant 4 heures sous une pression de 2 MPa à 350°C, au contact d'une charge constituée de 2% poids de soufre sous forme de diméthyldisulfure dans du n-heptane.50 ml of a β hydrodesulfurization catalyst in the form of extrudates with a specific surface area of 180 m 2 /g whose content (weight of oxide(s) relative to the total weight of the catalyst) in cobalt, molybdenum and phosphorus are respectively 4.4% by weight of CoO and 21.3% by weight of MoO 3 and 6.0% by weight of P 2 O 5 are placed in a fixed bed tubular hydrodesulfurization reactor. The catalyst is first sulfurized by treatment for 4 hours under a pressure of 2 MPa at 350°C, in contact with a filler consisting of 2% by weight of sulfur in the form of dimethyldisulfide in n-heptane.

La charge traitée D a un point initial d'ébullition de 160°C et un point final de 269°C. Sa teneur en soufre est de 5116 ppm poids et son indice de brome (IBr) est de 19.5 g/100 g ce qui correspond approximativement à 10% poids d'oléfines. La fraction de la charge D ayant un point d'ébullition compris entre 220°C et 269°C est de 26,3% poids.The treated feed D has an initial boiling point of 160°C and an end point of 269°C. Its sulfur content is 5116 ppm by weight and its bromine index (IBr) is 19.5 g/100 g which corresponds approximately to 10% by weight of olefins. The fraction of charge D having a boiling point between 220°C and 269°C is 26.3% by weight.

La charge D est traitée avec le catalyseur β, à une température de 300°C, sous une pression de 2 MPa, avec un rapport volumique hydrogène sur charge à traiter (H2/HC) de 300 NI/I et une VVH de 4 h-1. Après traitement, l'effluent est refroidi, l'hydrogène riche en H2S est séparé de l'effluent liquide, et l'effluent est soumis à un traitement de stripage par injection d'un flux d'hydrogène afin d'éliminer les traces résiduelles d'H2S dissous avant d'être analysé. Le tableau 2 indique le taux de désulfuration et la teneur en soufre et en mercaptans de l'effluent désulfuré. Tableau2 Analyse Mercaptans, ppm poids 12 Soufre total, ppm poids 34 Taux de désulfuration, % 99,3 Charge D is treated with catalyst β, at a temperature of 300°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to charge to be treated (H 2 /HC) of 300 NI/I and a VVH of 4 h -1 . After treatment, the effluent is cooled, the hydrogen rich in H 2 S is separated from the liquid effluent, and the effluent is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate the residual traces of dissolved H 2 S before being analyzed. Table 2 shows the desulfurization rate and the sulfur and mercaptan content of the desulfurized effluent. Table2 Analysis Mercaptans, ppm weight 12 Total sulfur, ppm weight 34 Desulfurization rate, % 99.3

Exemple 3 (comparatif)Example 3 (comparative)

Une charge E testée dans l'exemple 3 est un mélange contenant 50% poids de la charge C et de 50% poids de la charge D. Le point initial d'ébullition du mélange est de 61°C et le point final de 269°C. Sa teneur en soufre est de 2512 ppm poids et son indice de brome (IBr) est de 53,4 g/100 g ce qui correspond approximativement à 29,2 % poids d'oléfines.A charge E tested in Example 3 is a mixture containing 50% by weight of charge C and 50% by weight of charge D. The initial boiling point of the mixture is 61°C and the final point is 269°C. vs. Its sulfur content is 2512 ppm by weight and its bromine index (IBr) is 53.4 g/100 g which corresponds approximately to 29.2% by weight of olefins.

Cette charge E est d'abord traitée sur le catalyseur α, à une température de 330°C, sous une pression de 2 MPa, avec un rapport volumique hydrogène sur charge à traiter (H2/HC) de 300 NI/I et une VVH de 4 h-1. Après traitement, l'effluent est refroidi, l'hydrogène riche en H2S est séparé de l'effluent liquide, et l'effluent est soumis à un traitement de stripage par injection d'un flux d'hydrogène afin d'éliminer les traces résiduelles d'H2S dissous.This charge E is first treated on the catalyst α, at a temperature of 330°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to charge to be treated (H 2 /HC) of 300 NI/I and a VVH from 4 a.m. -1 . After treatment, the effluent is cooled, the hydrogen rich in H 2 S is separated from the liquid effluent, and the effluent is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate the residual traces of dissolved H 2 S.

L'effluent est ensuite séparé en deux coupes : une première coupe (coupe essence) avec un point final d'ébullition de 160°C et une seconde coupe avec un point initial de 160°C. Tableau 3 Analyse 1ère coupe 2nd coupe 61°C-160°C 160°C-269°C Mercaptans, ppm poids 6 8 Soufre total, ppm poids 6 49 Taux de désulfuration, % 99,2 99 Perte RON 9,8 Non applicable The effluent is then separated into two cuts: a first cut (petrol cut) with a final boiling point of 160°C and a second cut with an initial point of 160°C. Table 3 Analysis 1st cut 2nd cut 61°C-160°C 160°C-269°C Mercaptans, ppm weight 6 8 Total sulfur, ppm weight 6 49 Desulfurization rate, % 99.2 99 RON loss 9.8 Not applicable

Exemple 4 (selon l'invention)Example 4 (according to the invention)

La charge E utilisé dans l'exemple 3 est traitée dans un première étape d'hydrodésulfuration sur le catalyseur β, à une température de 260°C, sous une pression de 2 MPa, avec un rapport volumique hydrogène sur charge à traiter (H2/HC) de 300 NI/I et une VVH de 4 h-1. Après traitement, l'effluent issu de la première étape d'hydrodésulfuration est refroidi, l'hydrogène riche en H2S est séparé de l'effluent liquide, et l'effluent est soumis à un traitement de stripage par injection d'un flux d'hydrogène afin d'éliminer les traces résiduelles d'H2S dissous. L'effluent strippé constitue la charge F traitée dans la seconde étape d'hydrodésulfuration.The feed E used in Example 3 is treated in a first hydrodesulfurization step on the catalyst β, at a temperature of 260°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to feed to be treated (H 2 /HC) of 300 NI/I and a VVH of 4 h -1 . After treatment, the effluent from the first hydrodesulfurization step is cooled, the hydrogen rich in H 2 S is separated from the liquid effluent, and the effluent is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate residual traces of dissolved H 2 S. The stripped effluent constitutes the feedstock F treated in the second hydrodesulfurization step.

La charge F est ensuite traitée dans un deuxième étape d'hydrodésulfuration sur le catalyseur α, à une température de 280°C, sous une pression de 2 MPa, avec un rapport volumique hydrogène sur charge à traiter (H2/HC) de 300 l/l et une VVH de 4 h-1. Après traitement, l'effluent issu de la seconde étape d'hydrodésulfuration est refroidi, l'hydrogène riche en H2S est séparé de l'effluent liquide, et l'effluent est soumis à un traitement de stripage par injection d'un flux d'hydrogène afin d'éliminer les traces résiduelles d'H2S dissous.The feedstock F is then treated in a second hydrodesulfurization step on the α catalyst, at a temperature of 280°C, under a pressure of 2 MPa, with a volume ratio of hydrogen to feedstock to be treated (H 2 /HC) of 300. l/l and a VVH of 4 h -1 . After treatment, the effluent from the second hydrodesulfurization step is cooled, the hydrogen rich in H 2 S is separated from the liquid effluent, and the effluent is subjected to a stripping treatment by injection of a flow of hydrogen in order to eliminate residual traces of dissolved H 2 S.

L'effluent de la deuxième étape d'hydrodésulfuration est ensuite séparé en deux coupes : une première coupe (coupe essence) avec un point final d'ébullition de 160°C et une seconde coupe avec un point initial de 160°C. Tableau 4 Références 1ère coupe 2nd coupe 61°C-160°C 160°C-269°C Mercaptans, ppm poids 7 11 Soufre total, ppm poids 9 42 Taux de désulfuration, % 98,8 99,2 Perte RON 5,9 Non applicable The effluent from the second hydrodesulfurization stage is then separated into two cuts: a first cut (petrol cut) with a final boiling point of 160°C and a second cut with an initial point of 160°C. Table 4 References 1st cut 2nd cut 61°C-160°C 160°C-269°C Mercaptans, ppm weight 7 11 Total sulfur, ppm weight 9 42 Desulfurization rate, % 98.8 99.2 RON loss 5.9 Not applicable

L'exemple 4 montre qu'il est possible, à partir d'un mélange d'hydrocarbures comprenant au moins une première coupe d'hydrocarbures ayant une température d'ébullition comprise entre 61° et 160°C et dont la teneur en oléfines est de 42% poids et une seconde coupe d'hydrocarbures ayant une température d'ébullition comprise entre 160° et 269°C dont la fraction ayant un point d'ébullition supérieur à 220°C est de 26,3%, d'obtenir deux coupes désulfurées dont la teneur en soufre sont respectivement inférieure à 10 ppm poids soufre pour la coupe désulfurée ayant une température d'ébullition comprise entre 61°C et 160°C et inférieure à 50 ppm poids en soufre pour la coupe désulfurée ayant une température d'ébullition comprise entre 160° et 269°C tout en limitant la perte d'indice de RON liée notamment à l'hydrogénation d'une partie des oléfines présentes dans le mélange.Example 4 shows that it is possible, from a mixture of hydrocarbons comprising at least a first cut of hydrocarbons having a boiling temperature of between 61° and 160°C and whose olefin content is of 42% by weight and a second cut of hydrocarbons having a boiling point between 160° and 269°C of which the fraction having a boiling point greater than 220°C is 26.3%, to obtain two desulphurized cuts whose sulfur content are respectively less than 10 ppm by weight of sulfur for the desulphurized cut having a boiling temperature between 61°C and 160°C and less than 50 ppm by weight of sulfur for the desulphurized cut having a temperature of boiling between 160° and 269°C while limiting the loss of RON index linked in particular to the hydrogenation of part of the olefins present in the mixture.

Claims (12)

  1. Process for the concomitant production of two hydrocarbon cuts having low sulfur contents starting from a mixture of hydrocarbons having a starting boiling point of between 35°C and 100°C and a final boiling point of between 260°C and 340°C and having a total sulfur content of between 30 and 10 000 ppm by weight, said mixture of hydrocarbons consists of:
    • a first fraction comprising hydrocarbons having a range of boiling points of between the initial boiling point of the mixture and 160°C and the content of olefins of which is between 20% and 80% by weight of said first cut, the first fraction being chosen from an olefinic petrol cut resulting from a catalytic cracking, steam cracking, coking or visbreaking unit, the first fraction representing between 30% and 70% by weight of the mixture, and
    • a second fraction comprising hydrocarbons having a range of boiling points of between 160°C and the final boiling point of the mixture, said second fraction comprising at least 10% by weight of hydrocarbons having a range of boiling points of between 220°C and the final boiling point of the mixture, the second fraction being a light oil resulting from a catalytic cracking unit, the process comprising the following stages:
    a) in a first reactor, said mixture consisting of said first fraction and of said second fraction is treated in a first hydrodesulfurization stage in the presence of hydrogen and of a catalyst comprising at least one metal from group VIII, at least one metal from group VIB and a support, the content of metal(s) from group VIII being of between 1.5% and 9% by weight of oxide(s) of metal(s) from group VIII and the content of metal(s) from group VIB being of between 4% and 40% by weight of oxide(s) of metal (s) from group VIB, the molar ratio of metal(s) from group VIII to metal(s) from group VIB in the catalyst in oxide form is between 0.1 and 0.8, the first hydrodesulfurization stage being carried out at a temperature of between 200°C and 400°C, at a pressure of between 1 and 10 MPa, with a liquid space velocity of between 0.1 and 10 h-1 and with a volume of hydrogen/volume of mixture of hydrocarbons ratio of between 50 and 500 Slitre/litre;
    b) the hydrogen sulfide is removed from the partially desulfurized effluent resulting from stage a);
    c) in a second reactor, the partially desulfurized mixture resulting from stage b) is treated in a second hydrodesulfurization stage in the presence of hydrogen and of a catalyst comprising at least one element from group VIII, at least one element from group VIB and a support, the content of metal(s) from group VIII being of between 0.5% and 15% by weight of oxide(s) of metal(s) from group VIII and the content of metal (s) from group VIB being of between 1.5% and 60% by weight of oxide(s) of metal(s) from group VIB, the second hydrodesulfurization stage being carried out at a temperature of between 205°C and 500°C, at a pressure of between 1 and 3 MPa, with a liquid space velocity of between 1 and 10 h-1 and with a volume of hydrogen/volume of mixture ratio of between 50 and 500 Slitre/litre, the temperature of the second hydrodesulfurization stage c) being greater than that of the first hydrodesulfurization stage a); and
    d) the desulfurized mixture resulting from stage c) is fractionated into at least two light and heavy cuts of hydrocarbons, the light cut of hydrocarbons having an initial boiling point of between 35°C and 100°C and a final boiling point of between 160°C and 220°C and the total sulfur content of which is less than 50 ppm by weight and the heavy cut of hydrocarbons having an initial boiling point of between 160°C and 220°C and a final boiling point of between 260°C and 340°C.
  2. Process according to Claim 1, in which the catalyst of stage a) comprises a metal from group VIII chosen from nickel and cobalt and a metal from group VIB chosen from molybdenum and tungsten.
  3. Process according to Claim 2, in which the catalyst of stage a) comprises phosphorus.
  4. Process according to one of the preceding claims, in which the catalyst of stage c) comprises a metal from group VIII chosen from nickel and cobalt and a metal from group VIB chosen from molybdenum and tungsten.
  5. Process according to Claim 4, in which the catalyst of stage c) additionally comprises phosphorus.
  6. Process according to one of the preceding claims, in which the first fraction of hydrocarbons is a petrol cut resulting from a catalytic cracking unit.
  7. Process according to Claim 6, in which the first fraction of hydrocarbons is a cut of C6+ hydrocarbons obtained by distillation of a petrol cut resulting from a catalytic cracking unit.
  8. Process according to Claim 7, in which, before the distillation stage, the petrol cut was subjected to a stage of selective hydrogenation of the diolefins present in said petrol cut.
  9. Process according to one of the preceding claims, in which the temperature of stage c) is greater by at least 5°C than the temperature of stage a).
  10. Process according to one of the preceding claims, in which the temperature of stage c) is greater by at least 10°C than the temperature of stage a).
  11. Process according to Claims 6 and 8, in which, before stage a), a stage of mixing the first and second cuts of hydrocarbons is carried out upstream of the reactor of the first hydrodesulfurization stage.
  12. Process according to Claims 6 and 8, in which a mixing of the first and second cuts of hydrocarbons is carried out in the reactor of the first hydrodesulfurization stage.
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FR3014896A1 (en) 2015-06-19
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CN104726132B (en) 2018-12-07
EP2886629A1 (en) 2015-06-24
US9505993B2 (en) 2016-11-29
RU2014150770A (en) 2016-07-10
KR20150071665A (en) 2015-06-26
RU2652982C2 (en) 2018-05-04
US20150166907A1 (en) 2015-06-18
KR102276776B1 (en) 2021-07-12
FR3014896B1 (en) 2018-07-27
PL2886629T3 (en) 2024-03-25

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