CA1122620A - Process for the preparation of an aromatic hydrocarbon mixture - Google Patents
Process for the preparation of an aromatic hydrocarbon mixtureInfo
- Publication number
- CA1122620A CA1122620A CA319,382A CA319382A CA1122620A CA 1122620 A CA1122620 A CA 1122620A CA 319382 A CA319382 A CA 319382A CA 1122620 A CA1122620 A CA 1122620A
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- Prior art keywords
- catalyst
- fraction
- process according
- mixture
- natural gas
- Prior art date
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
- C10L1/00—Liquid carbonaceous fuels
- C10L1/04—Liquid carbonaceous fuels essentially based on blends of hydrocarbons
- C10L1/06—Liquid carbonaceous fuels essentially based on blends of hydrocarbons for spark ignition
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/87—Gallosilicates; Aluminogallosilicates; Galloborosilicates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/88—Ferrosilicates; Ferroaluminosilicates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/22—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
- C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
- C01B3/36—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using oxygen or mixtures containing oxygen as gasifying agents
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
- C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
- C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
- C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
- C07C1/04—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon from carbon monoxide with hydrogen
- C07C1/0425—Catalysts; their physical properties
- C07C1/043—Catalysts; their physical properties characterised by the composition
- C07C1/0435—Catalysts; their physical properties characterised by the composition containing a metal of group 8 or a compound thereof
- C07C1/044—Catalysts; their physical properties characterised by the composition containing a metal of group 8 or a compound thereof containing iron
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
- C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
- C07C1/04—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon from carbon monoxide with hydrogen
- C07C1/0485—Set-up of reactors or accessories; Multi-step processes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/06—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of zinc, cadmium or mercury
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- C07C2523/24—Chromium, molybdenum or tungsten
- C07C2523/26—Chromium
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
- C07C2523/72—Copper
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/88—Ferrosilicates; Ferroaluminosilicates
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Abstract
A B S T R A C T
Process for the preparation of aromatic gasoline from natural gas. Natural gas is converted into synthesis gas. The synthesis gas is converted into an aromatic hydrocarbon mixture over a catalyst containing a crystalline iron silicate. From the aromatic hydrocarbon mixture a C2?fraction, an isobutane fraction and an aromatic liquid gasoline fraction are separated. The C2?fraction is converted into synthesis gas. The isobutane fraction is converted by alkylation into a product from which a gasoline fraction is separated. The two gasoline fractions are mixed.
Process for the preparation of aromatic gasoline from natural gas. Natural gas is converted into synthesis gas. The synthesis gas is converted into an aromatic hydrocarbon mixture over a catalyst containing a crystalline iron silicate. From the aromatic hydrocarbon mixture a C2?fraction, an isobutane fraction and an aromatic liquid gasoline fraction are separated. The C2?fraction is converted into synthesis gas. The isobutane fraction is converted by alkylation into a product from which a gasoline fraction is separated. The two gasoline fractions are mixed.
Description
~lZ2620 A PROCESS FOR THE PREPARATION OF AN
AROMATIC HYDROCARBON MIXTURE
The invention relates to a process for the preparation of an aromatic hydrocarbon mixture from natural gas.
Aromatic hydrocarbon mixtures are used on a large scale as gasoline. They are, as a rule, obtained by catalytic reforming of aliphatic hydrocarbon mixtures based on mineral oil, which are boiling in the gasoline range.
In view of the increasing need of gasoline and the decreasing reserves of mineral oil there is a great interest in processes permitting the conversion, in an economically Justified way, of aliphatic hydrocarbons boiling below the gasoline range into aromatic hydro-carbon mixtures boiling in the gasoline range.
It is known that aliphatic hydrocarbons boiling below the gasoline range can be converted into a mixture of carbon monoxide and hydrogen, the so~called synthesis gas. It is further known that synthesis gas can be converted into a mixture of hydrocarbons, a part ~,~
~, of which boils in the gasoline range by contacting the synthesis gas with a suitable catalyst. Finally, it is known that isobutane can be converted into a hydro-carbon mixture boiling in the gasoline range by contact-ing the isobutane, together with lower olefins such aspropene and butene, with an alkylation catalyst.
The Applicant has carried out an investigation in order to find out how far the above-mentioned three processes can be used in the preparation of gasoline from natural gas. It has been found in this investigat-ion that an aromatic hydrocarbon mixture which is very suitable as gasoline can be prepared from natural gas by combining the three above-mentioned processes, provided that the following conditions are satisfied.
First of all, the natural gas should be converted into synthesis gas. Then, the synthesis gas should be converted into an aromatic hydrocarbon mixture, using a catalyst containing a crystalline silicate which (a) is thermally stable to temperatures above 600C, (b) after dehydration at 400C in vacuum, is capable of adsorbing more than 3 %w water at ~5C and saturated water vapour pressure, and (c) in dehydrated form, has the following overall composition, expressed in moles of the oxides:
O. _ - 3)(R)2/n ~ a Fe203. b Al203. c Ga203 /.
y (d SiO2. e GeO2), where R = one or more mono- or bivalent cations, a ~ 0.1, b ~, 0, c ~ O, a+b+c= 1, y ~, 10, d ~ 0.1, e ~ -d+e= ~, 1, and n = the valency of R.
From the aromatic hydrocarbon mixture thus obtain-ed a number of fractions should then be separated, viz.a C2 fraction which is recycled to the synthesis gas preparation, an isobutane-containing gaseous fraction which is contacted with an alkylation catalyst and an aromatic liquid fraction boiling in the gasoline range. Finally, a fraction boiling in the gasoline range is separated from the product obtained in the alkylation and this fraction is mixed with the aromatic gasoline fraction obtained earlier.
The present invention therefore relates to a process for the preparation of an aromatic hydrocarbon mixture from natural gas, in which (a) natural gas is converted into synthesis gas, ~b) the synthesis gas is corverted into an aromatic ~ .
~l;Z'~62~
hydrocarbon mixture, using a catalyst containing a crystalline silicate as defined hereinbefore, (c) a C2 fraction, an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range are separated from the aromatic hydrocarbon mixture, (d) the C2 fraction is recyled to step (a) of the process, (e) the isobutane-containing gaseous fraction is converted by alkylation into a product from which a fraction boiling in the gasoline range is separated, and (f) the two fractions boiling in the gasoline range obtained according to (c) and (e) are mixed.
Natural gas, from which the process according to the invention is started, consists substantially of saturated aliphatic hydrocarbons with four or less carbon atoms per molecule (C4 hydrocarbons), in particular methane, ethane, propane and butane. In addition to these C4 hydrocarbons, natural gas may - depending on its origin - also contain up to about 10% saturated aliphatic hydrocarbons with five or more carbon atoms (C5+ hydrocarbons), in particular hexane, heptane and octane. The latter saturated aliphatic hydrocarbons are liquid at normal temperature and pressure; in natural gas, however, they are present in the vapour phase. The process according to the Z~O
invention may start both from a so~called crude natural gas containing in addition to C4 hydrocarbons also C5+ hydrocarbons, and from a so called residual natural gas consisting substantially of C4 hydrocarbons and which is left, after a so-called natural gas condensate consisting substantially of c5+ hydrocarbons has been separated from a crude natural gas. In attractive variant of the process according to the invention is one in which a crude natural gas is separated into a residual natural gas and a natural gas condensate, the residual natural gas being used as the feed for step(a) of the process and the natural gas condensate as the feed component for step(b) of the process. Besides crude natural gas and residual natural gas a so-called dry gas which contains only the methane and ethane present in the natural gas can also very suitably be used as the feed for step(a). When only this C2 fraction of natural gas is used as the feed for step(a), LPG is also obtained as the end product in the process according to the invention.
In step(a) of the process natural gas or at least the C2 fraction thereof is converted into synthesis gas. This conversion can very conveniently be effected by catalytic steam reforming or by partial oxidation.
The catalytic steam reforming is preferably carried out by contacting the feed together with stea~ at a temperature of from 750 to 1000C and a pressure of a~
112Z62~) from 1 to 35 bar with a nickel, iron or platinum catalyst. The partial oxidation is preferably carried out by treating the feed with oxygen at a temperature of from 900 to 1600C and a pressure of from 1 to 35 bar.
The synthesis gas which has been prepared according to step(a) of the process is converted in step(b) into an aromatic hydrocarbon mixture, using a catalyst containing a crystalline sili-cate, which belongs to a special class. These silicates effect a high conversion of aliphatic hydrocarbons into aromatic hydrocar-bons in commercially desirable yields and are generally very activein conversion reactions in which aromatic hydrocarbons are involved.
In the process according to the invention preference is given to the use of silicates in which no gallium and germanium are present, in other words, silicates of which, in the above-mentioned overall composition, c and e are o. Such silicates are the subject of Canadian Patent Application No. 291,509 (see also United Kingdom Patent 1,555,928). Further,preference is given to the use of sili-cates of which, in the above-mentioned overall composition, a is greater than 0.5. Particular preference is given to silicates in which no aluminium is present, in other words, silicates of which, in the above-men-B
.
ll;~Z620 tioned overall composition, b is o. It should be noted that in thesilicates used in the process according to the invention, y is pre-ferably less than 600 and in particular less than 300. Finally, in the process according to the invention preference is given to silicates whose X-ray powder diffraction pattern has, inter alia, the reflections given in Table A of Canadian patent application No.
291,509.
In step(b) of the process synthesis gas should be converted into an aromatic hydrocarbon mixture. Step(b) may in itself be carried out as a one-step or as a two-step process. In the two-step process the cynthesis gas is contacted in the first step with a catalyst containing one or more metal components having catalytic activity for the conversion of an H2/CO mixture into hydrocarbons and/or oxygen-containing hydrocarbons ~for the sake of convenience further designated catalyst X). In the second step the product thus obtained is converted into an aromatic hydrocarbon mixture by con-tacting it under aromatization conditions with the crystalline silicate (for the sake of convenience designated catalyst Y). If step(b) is carried out as a two-step process using a natural gas 20 condensate as the feed component, this natural gas ~B
l~ZZ620 condensate may be added both to the feed for the first step and to the feed for the second step, or be divided between the two feeds. If step(b) is carried out as a one-step process, the synthesis gas is contacted with a bifunctional catalyst which contains, in addition to the crystalline silicate, one or more metal components having catalytic activity for the conversion of an H2/C0 mixture into hydrocarbons and/or oxygen-containing hydrocarbons. The bifunctional catalysts which may be used in step(b) of the process are preferably composed of two separate catalysts X and Y.
If an X-catalyst is used which is capable of converting an H2/C0 mixture into substantially oxygen-containing hydrocarbons, preference is given to a catalyst that is capable of converting the H2/C0 mixture substantially into methanol and/or dimethyl ether. For the conversion of an H2/C0 mixture substantially into methanol, catalysts containing one or more of the metals zinc, copper and chromium are very suitable. Preference is given to catalysts containing at least two of these metals such as the combinations zinc-copper, zinc-chromium and zinc-copper-chromium. Particular preference is given to the combination zinc-chromium. If desired, the said metal combinations may be placed on a carrier material.
By introducing an acid function into these catalysts, for instance by placing the metal combination on an ,, ll;~Z6ZO
acid carrier, it may be secured that, apart from the conversion of the H2/C0 mixture into methanol, a considerable part of the mixture will be converted into dimethyl ether. X-catalysts which are capable of converting an H2/C0 mixture substantially into hydro-carbons are referred to in the literature as Fischer-Tropsch catalysts. Such catalysts often contain one or more metals of the iron group or ruthenium together with one or more promoters to increase the activity and/or selectivity and sometimes a carrier material.
They can be prepared by precipitation, melting or by impregnation. If in step(b) of the process according to the invention use is made of a Fischer-Tropsch catalyst as X-catalyst, it is preferred to choose for this purpose an iron or cobalt catalyst, in particular such a catalyst which has been prepared by impregenation.
If desired, it is possible in step(b) of the process according to the invention to use X-catalysts which are capable of converting an H2/C0 mixture into a mixture containing both hydrocarbons and oxygen-containing hydrocarbons in comparable quantities. An example of an X-catalyst of this type is an iron-chromium oxide catalyst. If desired, it is also possible in step(b) of the process according to the invention to use mixtures of two or more X-catalysts, for instance a ll;~Z620 mixture of a first X-catalyst which is capable of converting an H2/C0 mixture substantially into hydro-carbons and a second X-catalyst which is capable of converting an H2/C0 mixture substantially into oxygen-containing hydrocarbons.
The crystalline silicates which are used as the catalyst in step(b) of the process according to the invention, are usually prepared from an aqueous mixture as the starting material which contains the following compounds in a given ratio: one or more compounds of an alkali metal, one or more compounds containing an organic cation or from which such a cation is formed during the preparation of the silicate, one or more silicon compounds, one or more iron compounds, and, optionally, one or more aluminium, gallium and/or germanium compounds. The preparation is effected by maintaining the mixture at elevated temperature until the silicate has been formed and then separating the crystals of the silicate from the mother liquor. Before being used in the process according to the invention the organic cations introduced during the preparation should be converted by calcining into hydrogen ions. In the process it is preferred to use silicates whose alkali metal content is less than 1 ~w and in particular less than 0.05 %w.
Such silicates can be prepared from the above-mentioned calcined silicates by ion exchange, for instance with 11;~;~620 an aqueous solution of an ammonium salt followed by calcining.
Step(b) of the process according to the invention is preferably carried out at a temperature of from 200 to 500C, a pressure of from 1 to 250 bar and a space velocity of from 50 to 50,000 Nl gas.l catalyst.h.
In the conversion of an H2/C0 mixture into hydro-carbons and in the conversion of oxygen-containing hydrocarbons into an aromatic hydrocarbon mixture in step(b) of the process water is formed. If step(a) of the process is carried out by catalytic steam reforming, it is preferred to recycle this water, at least partly, to step(a). If step(b) is carried out as a two-step process using an X-catalyst in the first step which contains one or more metal components having catalytic activity for the conversion of an H2/C0 mixture substantially into hydrocarbons, the water formed in the first step is preferably separated from the reaction product of the first step before the latter is contacted with catalyst Y. Non-converted synthesis gas which is present in the reaction product of the first step of the two-step process is preferably recycled to the first step.
In the process according to the invention a C2 fraction, an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range should be separated from the aromatic hydrocarbon , l~ZZ6ZO
mixture obtained according to step(b). The reaction product resulting from step(b) is preferably separated in step(c) into a C2- fraction, a propane fraction, an isobutane-containing fraction, an n-butane fraction, an aromatic liquid fraction boiling in the gasoline range and, optionally, water. In step(d) of the process the C2 fraction is recycled to step(a). If desired, the propane and/or n-butane fractions may also be recycled entirely or partly to step(a). Naturally, the propane and n-butane fractions may also be combined to LPG, if desired together with LPG which has been separated from the natural gas in the preparation of a C2 dry gas as the feed for the process according to the invention.
In step(e) of the process according to the invention the isobutane-containing gaseous fraction should be converted by alkylation into a product from which a fraction boiling in the gasoline range can be separated. This alkylation can very conveniently be
AROMATIC HYDROCARBON MIXTURE
The invention relates to a process for the preparation of an aromatic hydrocarbon mixture from natural gas.
Aromatic hydrocarbon mixtures are used on a large scale as gasoline. They are, as a rule, obtained by catalytic reforming of aliphatic hydrocarbon mixtures based on mineral oil, which are boiling in the gasoline range.
In view of the increasing need of gasoline and the decreasing reserves of mineral oil there is a great interest in processes permitting the conversion, in an economically Justified way, of aliphatic hydrocarbons boiling below the gasoline range into aromatic hydro-carbon mixtures boiling in the gasoline range.
It is known that aliphatic hydrocarbons boiling below the gasoline range can be converted into a mixture of carbon monoxide and hydrogen, the so~called synthesis gas. It is further known that synthesis gas can be converted into a mixture of hydrocarbons, a part ~,~
~, of which boils in the gasoline range by contacting the synthesis gas with a suitable catalyst. Finally, it is known that isobutane can be converted into a hydro-carbon mixture boiling in the gasoline range by contact-ing the isobutane, together with lower olefins such aspropene and butene, with an alkylation catalyst.
The Applicant has carried out an investigation in order to find out how far the above-mentioned three processes can be used in the preparation of gasoline from natural gas. It has been found in this investigat-ion that an aromatic hydrocarbon mixture which is very suitable as gasoline can be prepared from natural gas by combining the three above-mentioned processes, provided that the following conditions are satisfied.
First of all, the natural gas should be converted into synthesis gas. Then, the synthesis gas should be converted into an aromatic hydrocarbon mixture, using a catalyst containing a crystalline silicate which (a) is thermally stable to temperatures above 600C, (b) after dehydration at 400C in vacuum, is capable of adsorbing more than 3 %w water at ~5C and saturated water vapour pressure, and (c) in dehydrated form, has the following overall composition, expressed in moles of the oxides:
O. _ - 3)(R)2/n ~ a Fe203. b Al203. c Ga203 /.
y (d SiO2. e GeO2), where R = one or more mono- or bivalent cations, a ~ 0.1, b ~, 0, c ~ O, a+b+c= 1, y ~, 10, d ~ 0.1, e ~ -d+e= ~, 1, and n = the valency of R.
From the aromatic hydrocarbon mixture thus obtain-ed a number of fractions should then be separated, viz.a C2 fraction which is recycled to the synthesis gas preparation, an isobutane-containing gaseous fraction which is contacted with an alkylation catalyst and an aromatic liquid fraction boiling in the gasoline range. Finally, a fraction boiling in the gasoline range is separated from the product obtained in the alkylation and this fraction is mixed with the aromatic gasoline fraction obtained earlier.
The present invention therefore relates to a process for the preparation of an aromatic hydrocarbon mixture from natural gas, in which (a) natural gas is converted into synthesis gas, ~b) the synthesis gas is corverted into an aromatic ~ .
~l;Z'~62~
hydrocarbon mixture, using a catalyst containing a crystalline silicate as defined hereinbefore, (c) a C2 fraction, an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range are separated from the aromatic hydrocarbon mixture, (d) the C2 fraction is recyled to step (a) of the process, (e) the isobutane-containing gaseous fraction is converted by alkylation into a product from which a fraction boiling in the gasoline range is separated, and (f) the two fractions boiling in the gasoline range obtained according to (c) and (e) are mixed.
Natural gas, from which the process according to the invention is started, consists substantially of saturated aliphatic hydrocarbons with four or less carbon atoms per molecule (C4 hydrocarbons), in particular methane, ethane, propane and butane. In addition to these C4 hydrocarbons, natural gas may - depending on its origin - also contain up to about 10% saturated aliphatic hydrocarbons with five or more carbon atoms (C5+ hydrocarbons), in particular hexane, heptane and octane. The latter saturated aliphatic hydrocarbons are liquid at normal temperature and pressure; in natural gas, however, they are present in the vapour phase. The process according to the Z~O
invention may start both from a so~called crude natural gas containing in addition to C4 hydrocarbons also C5+ hydrocarbons, and from a so called residual natural gas consisting substantially of C4 hydrocarbons and which is left, after a so-called natural gas condensate consisting substantially of c5+ hydrocarbons has been separated from a crude natural gas. In attractive variant of the process according to the invention is one in which a crude natural gas is separated into a residual natural gas and a natural gas condensate, the residual natural gas being used as the feed for step(a) of the process and the natural gas condensate as the feed component for step(b) of the process. Besides crude natural gas and residual natural gas a so-called dry gas which contains only the methane and ethane present in the natural gas can also very suitably be used as the feed for step(a). When only this C2 fraction of natural gas is used as the feed for step(a), LPG is also obtained as the end product in the process according to the invention.
In step(a) of the process natural gas or at least the C2 fraction thereof is converted into synthesis gas. This conversion can very conveniently be effected by catalytic steam reforming or by partial oxidation.
The catalytic steam reforming is preferably carried out by contacting the feed together with stea~ at a temperature of from 750 to 1000C and a pressure of a~
112Z62~) from 1 to 35 bar with a nickel, iron or platinum catalyst. The partial oxidation is preferably carried out by treating the feed with oxygen at a temperature of from 900 to 1600C and a pressure of from 1 to 35 bar.
The synthesis gas which has been prepared according to step(a) of the process is converted in step(b) into an aromatic hydrocarbon mixture, using a catalyst containing a crystalline sili-cate, which belongs to a special class. These silicates effect a high conversion of aliphatic hydrocarbons into aromatic hydrocar-bons in commercially desirable yields and are generally very activein conversion reactions in which aromatic hydrocarbons are involved.
In the process according to the invention preference is given to the use of silicates in which no gallium and germanium are present, in other words, silicates of which, in the above-mentioned overall composition, c and e are o. Such silicates are the subject of Canadian Patent Application No. 291,509 (see also United Kingdom Patent 1,555,928). Further,preference is given to the use of sili-cates of which, in the above-mentioned overall composition, a is greater than 0.5. Particular preference is given to silicates in which no aluminium is present, in other words, silicates of which, in the above-men-B
.
ll;~Z620 tioned overall composition, b is o. It should be noted that in thesilicates used in the process according to the invention, y is pre-ferably less than 600 and in particular less than 300. Finally, in the process according to the invention preference is given to silicates whose X-ray powder diffraction pattern has, inter alia, the reflections given in Table A of Canadian patent application No.
291,509.
In step(b) of the process synthesis gas should be converted into an aromatic hydrocarbon mixture. Step(b) may in itself be carried out as a one-step or as a two-step process. In the two-step process the cynthesis gas is contacted in the first step with a catalyst containing one or more metal components having catalytic activity for the conversion of an H2/CO mixture into hydrocarbons and/or oxygen-containing hydrocarbons ~for the sake of convenience further designated catalyst X). In the second step the product thus obtained is converted into an aromatic hydrocarbon mixture by con-tacting it under aromatization conditions with the crystalline silicate (for the sake of convenience designated catalyst Y). If step(b) is carried out as a two-step process using a natural gas 20 condensate as the feed component, this natural gas ~B
l~ZZ620 condensate may be added both to the feed for the first step and to the feed for the second step, or be divided between the two feeds. If step(b) is carried out as a one-step process, the synthesis gas is contacted with a bifunctional catalyst which contains, in addition to the crystalline silicate, one or more metal components having catalytic activity for the conversion of an H2/C0 mixture into hydrocarbons and/or oxygen-containing hydrocarbons. The bifunctional catalysts which may be used in step(b) of the process are preferably composed of two separate catalysts X and Y.
If an X-catalyst is used which is capable of converting an H2/C0 mixture into substantially oxygen-containing hydrocarbons, preference is given to a catalyst that is capable of converting the H2/C0 mixture substantially into methanol and/or dimethyl ether. For the conversion of an H2/C0 mixture substantially into methanol, catalysts containing one or more of the metals zinc, copper and chromium are very suitable. Preference is given to catalysts containing at least two of these metals such as the combinations zinc-copper, zinc-chromium and zinc-copper-chromium. Particular preference is given to the combination zinc-chromium. If desired, the said metal combinations may be placed on a carrier material.
By introducing an acid function into these catalysts, for instance by placing the metal combination on an ,, ll;~Z6ZO
acid carrier, it may be secured that, apart from the conversion of the H2/C0 mixture into methanol, a considerable part of the mixture will be converted into dimethyl ether. X-catalysts which are capable of converting an H2/C0 mixture substantially into hydro-carbons are referred to in the literature as Fischer-Tropsch catalysts. Such catalysts often contain one or more metals of the iron group or ruthenium together with one or more promoters to increase the activity and/or selectivity and sometimes a carrier material.
They can be prepared by precipitation, melting or by impregnation. If in step(b) of the process according to the invention use is made of a Fischer-Tropsch catalyst as X-catalyst, it is preferred to choose for this purpose an iron or cobalt catalyst, in particular such a catalyst which has been prepared by impregenation.
If desired, it is possible in step(b) of the process according to the invention to use X-catalysts which are capable of converting an H2/C0 mixture into a mixture containing both hydrocarbons and oxygen-containing hydrocarbons in comparable quantities. An example of an X-catalyst of this type is an iron-chromium oxide catalyst. If desired, it is also possible in step(b) of the process according to the invention to use mixtures of two or more X-catalysts, for instance a ll;~Z620 mixture of a first X-catalyst which is capable of converting an H2/C0 mixture substantially into hydro-carbons and a second X-catalyst which is capable of converting an H2/C0 mixture substantially into oxygen-containing hydrocarbons.
The crystalline silicates which are used as the catalyst in step(b) of the process according to the invention, are usually prepared from an aqueous mixture as the starting material which contains the following compounds in a given ratio: one or more compounds of an alkali metal, one or more compounds containing an organic cation or from which such a cation is formed during the preparation of the silicate, one or more silicon compounds, one or more iron compounds, and, optionally, one or more aluminium, gallium and/or germanium compounds. The preparation is effected by maintaining the mixture at elevated temperature until the silicate has been formed and then separating the crystals of the silicate from the mother liquor. Before being used in the process according to the invention the organic cations introduced during the preparation should be converted by calcining into hydrogen ions. In the process it is preferred to use silicates whose alkali metal content is less than 1 ~w and in particular less than 0.05 %w.
Such silicates can be prepared from the above-mentioned calcined silicates by ion exchange, for instance with 11;~;~620 an aqueous solution of an ammonium salt followed by calcining.
Step(b) of the process according to the invention is preferably carried out at a temperature of from 200 to 500C, a pressure of from 1 to 250 bar and a space velocity of from 50 to 50,000 Nl gas.l catalyst.h.
In the conversion of an H2/C0 mixture into hydro-carbons and in the conversion of oxygen-containing hydrocarbons into an aromatic hydrocarbon mixture in step(b) of the process water is formed. If step(a) of the process is carried out by catalytic steam reforming, it is preferred to recycle this water, at least partly, to step(a). If step(b) is carried out as a two-step process using an X-catalyst in the first step which contains one or more metal components having catalytic activity for the conversion of an H2/C0 mixture substantially into hydrocarbons, the water formed in the first step is preferably separated from the reaction product of the first step before the latter is contacted with catalyst Y. Non-converted synthesis gas which is present in the reaction product of the first step of the two-step process is preferably recycled to the first step.
In the process according to the invention a C2 fraction, an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range should be separated from the aromatic hydrocarbon , l~ZZ6ZO
mixture obtained according to step(b). The reaction product resulting from step(b) is preferably separated in step(c) into a C2- fraction, a propane fraction, an isobutane-containing fraction, an n-butane fraction, an aromatic liquid fraction boiling in the gasoline range and, optionally, water. In step(d) of the process the C2 fraction is recycled to step(a). If desired, the propane and/or n-butane fractions may also be recycled entirely or partly to step(a). Naturally, the propane and n-butane fractions may also be combined to LPG, if desired together with LPG which has been separated from the natural gas in the preparation of a C2 dry gas as the feed for the process according to the invention.
In step(e) of the process according to the invention the isobutane-containing gaseous fraction should be converted by alkylation into a product from which a fraction boiling in the gasoline range can be separated. This alkylation can very conveniently be
2~ performed by contacting the fraction with a strong acid as the catalyst, such as sulphuric acid or hydrofluoric acid. Since the gaseous part of the reaction product of step(b), as a rule, contains only small amounts of olefins, the isobutane-containing gaseous fraction which is separated from it will often have too low an olefin content to permit a sufficient conversion of the isobutane present therein by alkylation. It is there-fore preferred to increase the olefin content of thefraction before subjecting it to alkylation. An increase in the olefin content of the isobutane-containing fraction can conveniently be effected by mixing the fractlon with an olefin-rich stream. This stream may come from an external source or be prepared from paraffins obtained in the process, such as a propane fraction, an n-butane fraction or an LPG fraction.
From these fractions an olefin-rich stream can very conveniently be prepared by dehydrogenation of these fractions or by subjecting them to thermal cracking, whereby ethene is formed as the main product and the desired olefin-rich stream is obtained as a by-product.
From the product obtained in the alkylation a fraction boiling in the gasoline range is separated and this fraction is then mixed in step(f) of the process according to the invention with the aromatic liquid fraction boiling in the gasoline range obtained in step(c). The non-converted isobutane is preferably separated from the product obtained in the alkylation and recycled to step(e). In order to increase the vapour pressure of the gasoline mixture thus obtained, light hydrocarbons are preferably added to it. Light hydro-carbons very suitable for use include n-butane and LPG, which may be obtained as products or by-products of the process.
Three process schemes for the conversion of natural gas into aromatic gasoline according to the invention will be explained in more detail hereinafter with the aid of figures.
5 Process_scheme I (see Fig.1) The process is carried out in an apparatus compris-ing successively a synthesis gas preparation section(1), a hydrocarbon preparation section(2), the first separation section(3)S a dehydrogenation section(4), an 10 alkylation section(5) and the second separation section(6). A mixture of natural gas(7), a C2 fraction (8), propane(9) and n-butane(10) is converted by partial oxidation with oxygen(11) and steam(12) into a synthesis gas(13). The synthesis gas(13) is converted over a 15 bifunctional catalyst according to the invention into an aromatic reaction product(14), which is separated into a C2 fraction(8), propane(15), isobutane(16), n-butane(17), an aromatic gasoline fraction(18) and water(19). The C2 fraction(8) is recycled to the 20 synthesis gas preparation section. n-Butane(17) is divided into two portions(10) and (20), of which portion(10) is recycled to the synthesis gas preparation section. Propane(15) is converted by dehydrogenation into a mixture of propene and propane(21). Isobutane(16) 25 is alkylated together with isobutane(22) and the mixture of propene and propane(21). The alkylated product(23) is separated into propane(9), isobutane(22) and a l~ZZ620 gasoline fraction(24). Propane(9) is recycled to the synthesis gas preparation section and isobutane(22) is recycled to the alkylation section. The gasoline fraction(24) is mixed with the gasoline fraction(18) and with n-butane portion(20) to form gasoline(25).
Process scheme II (see Fig.1) The process is carried out in the same apparatus as used in process scheme I and in substantially the same way as described therein, however, with this difference that in the present case propane(9) is conducted to the dehydrogenation section(4) instead of to the synthesis gas preparation section(1).
Process scheme III (see Fig.2) The process is carried out in an apparatus 15 comprising successively the first separation section(1), a synthesis gas preparation section(2), a methanol preparation section(3), the second separation section(4), a hydrocarbon preparation section(5), the third separation section(6), an alkylation section(7) and the fourth section(8). Natural gas(9) is separated into a C2 fraction(10) and a C3+ fraction(11). A mixture of the C2 fraction(10) and a C2 fraction(12) is convert-ed by partial oxidation with oxygen(13) and steam(14) into synthesis gas(15). A mixture of the synthesis gas(15) and a synthesis gas(16) is converted over a methanol synthesis catalyst into a reaction product~17), which ia separated into non-converted synthesis gas(16) .~2~
and methanol(18). Synthesis gas(16) is recycled to the methanol preparation section. Methanol(18) is converted over a crystalline silicate according to the invention into an aromatic reaction product(19) which is separated into a C2 fraction(12), propane(20), isobutane(21), n-butane(22), an aromatic gasoline fraction(23) and water(24). The C2 fraction(12) is recycled to the synthesis gas preparation section.
n-Butane(22) is separated into two portions(25) and (26). Isobutane(21) is alkylated together with iso-butane(27) and a propene/butene stream(28) originating from an external source. The alkylated product(29) is separated into isobutene(27) and a gasoline fraction(30).
Isobutane(27) is recycled to the alkylation section.
Gasoline fraction(30) is mixed with gasoline fraction(23) and with n-butane portion(26) to form gasoline(31).
C3* fraction(11) is mixed with propane(20) and n-butane portion(25) to form LPG(32).
Process scheme IV (see Fig.2) The process is carried out in the same apparatus as used in process scheme III and in substantially the same way as described therein, however with this differ-ence that in the present case for the preparation of an aromatic reaction product(19) a natural gas condens-ate(18a) is used, in addition to methanol(18), as the feed component for the hydrocarbon preparation section.
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The present patent application also comprises apparatus for carrying out the process according to the invention, as schema~ically shown in Figs. 1 and 2.
The invention will now be further explained with the aid of the following examples.
A crystalline iron silicate (silicate A) was prepared as follows. A mixture of Fe(N03)3, SiO29NaNO3 and / (C3H7)4N /OH in water with the molar composition Na 0. 1.5 / (C3H7)4N_/20. 0.125 Fe203 2 1O 468 H20 was heated for 48 hours in an autoclave at 150C under autogenous pressure. After the reactlon mixture had cooled down, the silicate formed was filter-ed off, washed with water until the pH of the wash water was about 8 and dried for two hours at 120C.
Silicate A thus prepared had the following chemical composition: 0.8 / (C3H7)4_/20. 3 2 2 3 200 SiO2. 55 H20. The silicate had an X-ray powder diffraction pattern substantially as given in Table B
of United ICingdom patent No. l,555,928. The silicate was thermally stable to temperatures higher than 900C and was capable, after dehydration at 400C, of adsorbing 7 %w water in v~cuum at 25C and saturated water vapour pressure. With silicate A as the starting material, silicate B was prepared by successively calcining silicate A at 500 C, boiling with 1.0 molar NH4N03 solution, washing with water, boiling again with 1.0 molar NH4N03 solution and washing, drying at ~ ' 120C and calcining at 500C.
A catalyst C was prepared by thoroughly mixing a Co/Th/Mg/SiO2 Fischer-Tropsch catalyst, prepared by impregnation, and silicate B in a weight ratio of 1:2.
Example I
This example was carried out according to process scheme I. The starting material was a natural gas of the following composition in %v:
C1 95.9 C3 0.5 C4 0.2 C5 0.2 A mixture of 90 parts by volume of this natural gas, 9 parts by volume of a C2- recycle stream and 1.5 parts by volume of a combined propane and n-butane recycle stream was used as the feed for the preparatlon of synthesis gas by partial oxidation. 70 Parts by volume of oxygen and 0.05 part by volume of water were added to the hydrocarbon mixture and the partial oxidation was carried out at 1500C and 5 bar. After purification of the reaction product a synthesis gas was obtained which consisted of 35 parts by volume of carbon monoxide and 65 parts by volume of hydrogen.
This synthesis gas was contacted at a temperature of 280C, a pressure of 30 bar and a space velocity of 250 l.l 1.h 1 with catalyst C. The conversion of the synthesis gas was 95~. The hydrocarbon mixture obtained had the following composition in %w:
n-c4 i-C4 2 C5+ gasoline 60 The olefin content of both the C3 and the C4 fractlons was less than 1 %w. The reaction product was separated by cooling into a C2 fraction and a C3+
fraction. The C2 fraction was recycled to the reactor in which the partial oxidation of the natural gas was carried out. The C3+ fraction was separated into a propane fraction, an isobutane fraction, an n-butane fraction and a C5+ gasoline fraction. The propane fraction was converted into a mixture of propane and propene by dehydrogenation at 600C over a Cr203 catalyst. The conversion of propane into propene was 32%. The mixture of propane and propene thus obtained was mixed with the isobutane fraction and the mixture was converted by contacting it at 40C with an HF
alkylation catalyst. From the product obtained in the alkylation a propane fraction, an isobutane fraction and a gasoline fraction were separated. By isobutane recycling a constant isobutane/olefin ratio of 14 was maintained in the alkylation reactor. The yield of - ~
alkylation gasoline was 95%. The alkylation gasoline was mixed with the gasoline obtained earlier in the process. To bring the vapour pressure of the mixture to the proper value, part of the n-butane fraction was added to it. The gasoline thus prepared had an octane number (CRON) of 90. The remaining part of the n-butane fraction obtained from the C3~ fraction of the hydrocarbon synthesis product and the propane fraction obtained from the alkylation product were recycled to the reactor in which the partial oxidation of the natural gas was effected .
Example II
This example was carried out according to process scheme III. 100 Parts by volume of natural gas were separated into 96 parts by volume of C1/C2 fraction (dry gas) and 4 parts by volume of C3/C4 fraction. A
mixture of the 96 parts by volume of the C1/C2 fraction and 4 parts by volume of a C2- recycle stream was used as the feed for the preparation of synthesis gas by partial oxidation. 70 Parts by volume of oxygen and 0.05 part by volume of water were added to the hydro-carbon mixture and the partial oxidation was carried out at 1500C and 5 bar. After purification of the reaction product a synthesis gas was obtained which consisted of 35 parts by volume of carbon monoxide and 65 parts by volume of hydrogen. 100 Parts by volume of this synthesis gas were mixed with 2 parts by volume a~ ~
of water and the mixture was contacted at a temperature of 375C, a pressure of 80 bar and a space velocity of 25,000 l.l 1.h 1 with a ZnO-Cr203 methanol synthesis catalyst. From the reaction product methanol was 5 separated by cooling. After removal of C02 the non-converted synthesis gas was recycled to the reactor in which the methanol synthesis was effected. Methanol was converted into an aromatic hydrocarbon mixture by contacting it at a temperature of 350C, a pressure of 5 bar and a space velocity of 0.5 l.l 1.h 1 with silicate B. The conversion of methanol was almost 100%.
The hydrocarbon mixture obtained had the following composition in %w:
C1 + C2 11.4 C3 + n-C4 7.2 i-C4 2.1 C5+ gasoline79.3 The olefin content of both the C3 and the C4 fractions was less than 1 %w. The reaction product was separated by cooling into a C2 fraction and a C3+
fraction. The C2 fraction was recycled to the reactor in which the partial oxidation of the C2- fraction of the natural gas was carried out. The C3+ fraction was separated into a propane fraction, an isobutane fraction, an n-butane fraction and a C5+ gasoline fraction. The isobutane fraction was mixed with 80 %v of a C3-C5 olefin mixture originating from an external source and ~. .
-" ll;~Z620 the mixture was converted by contacting it at 40C
with an HF alkylation catalyst. By isobutane recycling a constant isobutane/olefin ratio of 14 was maintained in the alkylation reactor. The alkylate which was obtained in a yield of 95% was mixed with the gasoline obtained earlier in the process. To bring the vapour pressure of the mixture to the proper value, part of the n-butane fraction was added to it. The gasoline thus prepared had an octane number (CRON) of 92. The remaining part of the n-butane fraction and the propane fraction obtained from the C3+ fraction of the hydro-carbon synthesis product were mixed with the C3/C4 fraction separated from the natural gas to form LPG.
From these fractions an olefin-rich stream can very conveniently be prepared by dehydrogenation of these fractions or by subjecting them to thermal cracking, whereby ethene is formed as the main product and the desired olefin-rich stream is obtained as a by-product.
From the product obtained in the alkylation a fraction boiling in the gasoline range is separated and this fraction is then mixed in step(f) of the process according to the invention with the aromatic liquid fraction boiling in the gasoline range obtained in step(c). The non-converted isobutane is preferably separated from the product obtained in the alkylation and recycled to step(e). In order to increase the vapour pressure of the gasoline mixture thus obtained, light hydrocarbons are preferably added to it. Light hydro-carbons very suitable for use include n-butane and LPG, which may be obtained as products or by-products of the process.
Three process schemes for the conversion of natural gas into aromatic gasoline according to the invention will be explained in more detail hereinafter with the aid of figures.
5 Process_scheme I (see Fig.1) The process is carried out in an apparatus compris-ing successively a synthesis gas preparation section(1), a hydrocarbon preparation section(2), the first separation section(3)S a dehydrogenation section(4), an 10 alkylation section(5) and the second separation section(6). A mixture of natural gas(7), a C2 fraction (8), propane(9) and n-butane(10) is converted by partial oxidation with oxygen(11) and steam(12) into a synthesis gas(13). The synthesis gas(13) is converted over a 15 bifunctional catalyst according to the invention into an aromatic reaction product(14), which is separated into a C2 fraction(8), propane(15), isobutane(16), n-butane(17), an aromatic gasoline fraction(18) and water(19). The C2 fraction(8) is recycled to the 20 synthesis gas preparation section. n-Butane(17) is divided into two portions(10) and (20), of which portion(10) is recycled to the synthesis gas preparation section. Propane(15) is converted by dehydrogenation into a mixture of propene and propane(21). Isobutane(16) 25 is alkylated together with isobutane(22) and the mixture of propene and propane(21). The alkylated product(23) is separated into propane(9), isobutane(22) and a l~ZZ620 gasoline fraction(24). Propane(9) is recycled to the synthesis gas preparation section and isobutane(22) is recycled to the alkylation section. The gasoline fraction(24) is mixed with the gasoline fraction(18) and with n-butane portion(20) to form gasoline(25).
Process scheme II (see Fig.1) The process is carried out in the same apparatus as used in process scheme I and in substantially the same way as described therein, however, with this difference that in the present case propane(9) is conducted to the dehydrogenation section(4) instead of to the synthesis gas preparation section(1).
Process scheme III (see Fig.2) The process is carried out in an apparatus 15 comprising successively the first separation section(1), a synthesis gas preparation section(2), a methanol preparation section(3), the second separation section(4), a hydrocarbon preparation section(5), the third separation section(6), an alkylation section(7) and the fourth section(8). Natural gas(9) is separated into a C2 fraction(10) and a C3+ fraction(11). A mixture of the C2 fraction(10) and a C2 fraction(12) is convert-ed by partial oxidation with oxygen(13) and steam(14) into synthesis gas(15). A mixture of the synthesis gas(15) and a synthesis gas(16) is converted over a methanol synthesis catalyst into a reaction product~17), which ia separated into non-converted synthesis gas(16) .~2~
and methanol(18). Synthesis gas(16) is recycled to the methanol preparation section. Methanol(18) is converted over a crystalline silicate according to the invention into an aromatic reaction product(19) which is separated into a C2 fraction(12), propane(20), isobutane(21), n-butane(22), an aromatic gasoline fraction(23) and water(24). The C2 fraction(12) is recycled to the synthesis gas preparation section.
n-Butane(22) is separated into two portions(25) and (26). Isobutane(21) is alkylated together with iso-butane(27) and a propene/butene stream(28) originating from an external source. The alkylated product(29) is separated into isobutene(27) and a gasoline fraction(30).
Isobutane(27) is recycled to the alkylation section.
Gasoline fraction(30) is mixed with gasoline fraction(23) and with n-butane portion(26) to form gasoline(31).
C3* fraction(11) is mixed with propane(20) and n-butane portion(25) to form LPG(32).
Process scheme IV (see Fig.2) The process is carried out in the same apparatus as used in process scheme III and in substantially the same way as described therein, however with this differ-ence that in the present case for the preparation of an aromatic reaction product(19) a natural gas condens-ate(18a) is used, in addition to methanol(18), as the feed component for the hydrocarbon preparation section.
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l~LT ~Z6~ZO
The present patent application also comprises apparatus for carrying out the process according to the invention, as schema~ically shown in Figs. 1 and 2.
The invention will now be further explained with the aid of the following examples.
A crystalline iron silicate (silicate A) was prepared as follows. A mixture of Fe(N03)3, SiO29NaNO3 and / (C3H7)4N /OH in water with the molar composition Na 0. 1.5 / (C3H7)4N_/20. 0.125 Fe203 2 1O 468 H20 was heated for 48 hours in an autoclave at 150C under autogenous pressure. After the reactlon mixture had cooled down, the silicate formed was filter-ed off, washed with water until the pH of the wash water was about 8 and dried for two hours at 120C.
Silicate A thus prepared had the following chemical composition: 0.8 / (C3H7)4_/20. 3 2 2 3 200 SiO2. 55 H20. The silicate had an X-ray powder diffraction pattern substantially as given in Table B
of United ICingdom patent No. l,555,928. The silicate was thermally stable to temperatures higher than 900C and was capable, after dehydration at 400C, of adsorbing 7 %w water in v~cuum at 25C and saturated water vapour pressure. With silicate A as the starting material, silicate B was prepared by successively calcining silicate A at 500 C, boiling with 1.0 molar NH4N03 solution, washing with water, boiling again with 1.0 molar NH4N03 solution and washing, drying at ~ ' 120C and calcining at 500C.
A catalyst C was prepared by thoroughly mixing a Co/Th/Mg/SiO2 Fischer-Tropsch catalyst, prepared by impregnation, and silicate B in a weight ratio of 1:2.
Example I
This example was carried out according to process scheme I. The starting material was a natural gas of the following composition in %v:
C1 95.9 C3 0.5 C4 0.2 C5 0.2 A mixture of 90 parts by volume of this natural gas, 9 parts by volume of a C2- recycle stream and 1.5 parts by volume of a combined propane and n-butane recycle stream was used as the feed for the preparatlon of synthesis gas by partial oxidation. 70 Parts by volume of oxygen and 0.05 part by volume of water were added to the hydrocarbon mixture and the partial oxidation was carried out at 1500C and 5 bar. After purification of the reaction product a synthesis gas was obtained which consisted of 35 parts by volume of carbon monoxide and 65 parts by volume of hydrogen.
This synthesis gas was contacted at a temperature of 280C, a pressure of 30 bar and a space velocity of 250 l.l 1.h 1 with catalyst C. The conversion of the synthesis gas was 95~. The hydrocarbon mixture obtained had the following composition in %w:
n-c4 i-C4 2 C5+ gasoline 60 The olefin content of both the C3 and the C4 fractlons was less than 1 %w. The reaction product was separated by cooling into a C2 fraction and a C3+
fraction. The C2 fraction was recycled to the reactor in which the partial oxidation of the natural gas was carried out. The C3+ fraction was separated into a propane fraction, an isobutane fraction, an n-butane fraction and a C5+ gasoline fraction. The propane fraction was converted into a mixture of propane and propene by dehydrogenation at 600C over a Cr203 catalyst. The conversion of propane into propene was 32%. The mixture of propane and propene thus obtained was mixed with the isobutane fraction and the mixture was converted by contacting it at 40C with an HF
alkylation catalyst. From the product obtained in the alkylation a propane fraction, an isobutane fraction and a gasoline fraction were separated. By isobutane recycling a constant isobutane/olefin ratio of 14 was maintained in the alkylation reactor. The yield of - ~
alkylation gasoline was 95%. The alkylation gasoline was mixed with the gasoline obtained earlier in the process. To bring the vapour pressure of the mixture to the proper value, part of the n-butane fraction was added to it. The gasoline thus prepared had an octane number (CRON) of 90. The remaining part of the n-butane fraction obtained from the C3~ fraction of the hydrocarbon synthesis product and the propane fraction obtained from the alkylation product were recycled to the reactor in which the partial oxidation of the natural gas was effected .
Example II
This example was carried out according to process scheme III. 100 Parts by volume of natural gas were separated into 96 parts by volume of C1/C2 fraction (dry gas) and 4 parts by volume of C3/C4 fraction. A
mixture of the 96 parts by volume of the C1/C2 fraction and 4 parts by volume of a C2- recycle stream was used as the feed for the preparation of synthesis gas by partial oxidation. 70 Parts by volume of oxygen and 0.05 part by volume of water were added to the hydro-carbon mixture and the partial oxidation was carried out at 1500C and 5 bar. After purification of the reaction product a synthesis gas was obtained which consisted of 35 parts by volume of carbon monoxide and 65 parts by volume of hydrogen. 100 Parts by volume of this synthesis gas were mixed with 2 parts by volume a~ ~
of water and the mixture was contacted at a temperature of 375C, a pressure of 80 bar and a space velocity of 25,000 l.l 1.h 1 with a ZnO-Cr203 methanol synthesis catalyst. From the reaction product methanol was 5 separated by cooling. After removal of C02 the non-converted synthesis gas was recycled to the reactor in which the methanol synthesis was effected. Methanol was converted into an aromatic hydrocarbon mixture by contacting it at a temperature of 350C, a pressure of 5 bar and a space velocity of 0.5 l.l 1.h 1 with silicate B. The conversion of methanol was almost 100%.
The hydrocarbon mixture obtained had the following composition in %w:
C1 + C2 11.4 C3 + n-C4 7.2 i-C4 2.1 C5+ gasoline79.3 The olefin content of both the C3 and the C4 fractions was less than 1 %w. The reaction product was separated by cooling into a C2 fraction and a C3+
fraction. The C2 fraction was recycled to the reactor in which the partial oxidation of the C2- fraction of the natural gas was carried out. The C3+ fraction was separated into a propane fraction, an isobutane fraction, an n-butane fraction and a C5+ gasoline fraction. The isobutane fraction was mixed with 80 %v of a C3-C5 olefin mixture originating from an external source and ~. .
-" ll;~Z620 the mixture was converted by contacting it at 40C
with an HF alkylation catalyst. By isobutane recycling a constant isobutane/olefin ratio of 14 was maintained in the alkylation reactor. The alkylate which was obtained in a yield of 95% was mixed with the gasoline obtained earlier in the process. To bring the vapour pressure of the mixture to the proper value, part of the n-butane fraction was added to it. The gasoline thus prepared had an octane number (CRON) of 92. The remaining part of the n-butane fraction and the propane fraction obtained from the C3+ fraction of the hydro-carbon synthesis product were mixed with the C3/C4 fraction separated from the natural gas to form LPG.
Claims (18)
1. A process for the preparation of an aromatic hydrocarbon mixture from natural gas, characterized in that (a) natural gas is converted into synthesis gas;
(b) the synthesis gas is converted into an aromatic hydrocarbon mixture, using a catalyst containing a crystalline silicate which (1) is thermally stable to temperatures above 600°C, (2) after dehydration at 400°C in vacuum, is capable of adsorbing more than 3 %w water at 25°C and saturated water vapour pressure, and (3) in dehydrated form, has the following overall composition, expressed in moles of the oxides:
(1.0 + 0.3)(R)n/20.[a Fe203. b A12O3. c Ga203].
y (d SiO2. e Ge02), where R = one or more mono- or bivalent cations, a ? 0.1, b ? 0, c ? 0, a+b+c = 1, y ? 10, d ? 0.1, e ? 0, d+e = 1, and n = the valency of R;
(c) from the aromatic hydrocarbon mixture a C2? fraction, an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range are separated;
(d) the C2 fraction is recycled to step(a) of the process;
(e) the isobutane-containing gaseous fraction is convert-ed by alkylation into a product from which a fraction boiling in the gasoline range is separated;
and (f) the two fractions boiling in the gasoline range obtained according to (c) and (e) are mixed.
(b) the synthesis gas is converted into an aromatic hydrocarbon mixture, using a catalyst containing a crystalline silicate which (1) is thermally stable to temperatures above 600°C, (2) after dehydration at 400°C in vacuum, is capable of adsorbing more than 3 %w water at 25°C and saturated water vapour pressure, and (3) in dehydrated form, has the following overall composition, expressed in moles of the oxides:
(1.0 + 0.3)(R)n/20.[a Fe203. b A12O3. c Ga203].
y (d SiO2. e Ge02), where R = one or more mono- or bivalent cations, a ? 0.1, b ? 0, c ? 0, a+b+c = 1, y ? 10, d ? 0.1, e ? 0, d+e = 1, and n = the valency of R;
(c) from the aromatic hydrocarbon mixture a C2? fraction, an isobutane-containing gaseous fraction and an aromatic liquid fraction boiling in the gasoline range are separated;
(d) the C2 fraction is recycled to step(a) of the process;
(e) the isobutane-containing gaseous fraction is convert-ed by alkylation into a product from which a fraction boiling in the gasoline range is separated;
and (f) the two fractions boiling in the gasoline range obtained according to (c) and (e) are mixed.
2. A process according to claim 1, characterized in that the preparation of the synthesis gas is carried out according to step(a), starting from a dry gas or residual gas separated from natural gas.
3. A process according to claim 2, characterized in that a natural gas condensate separated from natural gas is used as the feed component for step (b).
4. A process according to claim 1, characterized in that the conversion of the natural gas into synthesis gas is effected by catalytic steam reforming or by partial oxidation.
5. A process according to claim 1, characterized in that the catalyst which is used in step(b) contains a crystalline silicate of which, in the formula giving the overall composition, c and e are equal to 0.
6. A process according to claim 1, characterized in that the catalyst which is used in step(b) contains a crystalline silicate of which, in the formula giving the overall composition, a is greater than 0.5.
7. A process according to claim 1, characterized in that the catalyst which is used in step(b) contains a crystalline silicate of which, in the formula giving the overall composition, y is less than 600.
8. A process according to claim 1, characterized in that the catalyst which is used in step(b) contains a crystalline silicate with an alkali metal content of less than 1 %w.
9. A process according to claim 1, characterized in that step(b) is carried out as a two-step process by contacting the synthesis gas in the first step with a catalyst containing one or more metal components having catalytic activity for the conversion of an H2/C0 mixture into hydrocarbons and/or oxygen-containing hydrocarbons (catalyst X) and by converting the product thus obtained in the second step into an aromatic hydrocarbon mixture by contacting it under aromatization conditions with the crystalline silicate (catalyst Y).
10. A process according to claim 1, characterized in that step(b) is carried out as a one-step process by contacting the synthesis gas with a bifunctional catalyst composed of two separate catalysts of which one catalyst (catalyst X) contains one or more metal components having catalytic activity for the conversion of an H2/CO mixture into hydrocarbons and the other catalyst (catalyst Y) is the crystalline silicate.
11. A process according to claim 9 or 10, characterized in that a catalyst X is used which is capable of converting an H2/CO mixture into methanol and/or dimethyl ether.
12. A process according to claim 9 or 10, characterized in that catalyst X is capable of converting an H2/CO mixture into methanol and/or dimethyl ether, and contains at least two of the metals zinc, copper and chromium.
13. A process according to claim 9 or 10, characterized in that catalyst X is a Fischer-Tropsch catalyst.
14. A process according to claim 9 or 10, characterized in that catalyst X is a Fischer-Tropsch catalyst which contains an iron or cobalt catalyst.
15. A process according to claim 1, characterized in that step(b) is carried out at a temperature from 200 to 500°C, a pressure from 1 to 250 bar and a space velocity from 50 to 50,000.
16. A process according to claim 1, characterized in that step(a) is carried out by catalytic steam reforming and that water formed as a by-product during step(b) is recycled, at least partly, to step(a).
17. A process according to claim 1, characterized in that the reaction product resulting from step(b) is separated in step(c) into a C2? fraction, a propane fraction, an isobutane fraction, a n-butane fraction, and an aromatic liquid fraction boiling in the gasoline range.
18. A process according to claim 1, characterized in that propane and/or n-butane which is formed in the process is recycled at least in part to step(a).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7803707 | 1978-04-07 | ||
| NL7803707A NL7803707A (en) | 1978-04-07 | 1978-04-07 | Gasoline prodn. from natural gas - by conversion to synthesis gas, hydrocarbon synthesis, fractionation and isobutane alkylation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122620A true CA1122620A (en) | 1982-04-27 |
Family
ID=19830613
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA319,382A Expired CA1122620A (en) | 1978-04-07 | 1979-01-10 | Process for the preparation of an aromatic hydrocarbon mixture |
Country Status (4)
| Country | Link |
|---|---|
| AU (1) | AU527900B2 (en) |
| CA (1) | CA1122620A (en) |
| NL (1) | NL7803707A (en) |
| NZ (1) | NZ190105A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2529099A2 (en) * | 1982-06-25 | 1983-12-30 | Azote & Prod Chim | Catalyst for converting synthesis gas to hydrocarbon(s) - comprises transition metals and de:aluminated mordenite |
| EP0192289A2 (en) * | 1985-02-22 | 1986-08-27 | Shell Internationale Researchmaatschappij B.V. | Process for the preparation of an aromatic hydrocarbons-containing mixture |
| EP0269297A1 (en) * | 1986-11-06 | 1988-06-01 | The British Petroleum Company p.l.c. | Process for the production of aromatic hydrocarbons incorporating by-product utilisation |
| US9938217B2 (en) | 2016-07-01 | 2018-04-10 | Res Usa, Llc | Fluidized bed membrane reactor |
| US9981896B2 (en) | 2016-07-01 | 2018-05-29 | Res Usa, Llc | Conversion of methane to dimethyl ether |
| US10189763B2 (en) | 2016-07-01 | 2019-01-29 | Res Usa, Llc | Reduction of greenhouse gas emission |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL176551C (en) * | 1979-04-25 | 1985-05-01 | Shell Int Research | PROCESS FOR PREPARING AN AROMATIC HYDROCARBON MIXTURE BY CATALYTIC CONVERSION OF A MIXTURE OF CARBON MONOXIDE AND HYDROGEN. |
| NL8002582A (en) * | 1980-05-06 | 1981-12-01 | Shell Int Research | PROCESS FOR PREPARING HYDROCARBONS. |
| EP0084469B1 (en) * | 1982-01-14 | 1984-12-27 | Societe Chimique De La Grande Paroisse, Azote Et Produits Chimiques | Synthesis gas conversion catalysts |
| FR2519563B1 (en) * | 1982-01-14 | 1986-01-10 | Azote & Prod Chim | SYNTHESIS GAS CONVERSION CATALYSTS |
-
1978
- 1978-04-07 NL NL7803707A patent/NL7803707A/en not_active Application Discontinuation
-
1979
- 1979-01-10 CA CA319,382A patent/CA1122620A/en not_active Expired
- 1979-04-05 NZ NZ190105A patent/NZ190105A/en unknown
- 1979-04-05 AU AU45768/79A patent/AU527900B2/en not_active Ceased
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2529099A2 (en) * | 1982-06-25 | 1983-12-30 | Azote & Prod Chim | Catalyst for converting synthesis gas to hydrocarbon(s) - comprises transition metals and de:aluminated mordenite |
| EP0192289A2 (en) * | 1985-02-22 | 1986-08-27 | Shell Internationale Researchmaatschappij B.V. | Process for the preparation of an aromatic hydrocarbons-containing mixture |
| EP0192289A3 (en) * | 1985-02-22 | 1987-08-05 | Shell Internationale Research Maatschappij B.V. | Process for the preparation of an aromatic hydrocarbons-containing mixture |
| EP0269297A1 (en) * | 1986-11-06 | 1988-06-01 | The British Petroleum Company p.l.c. | Process for the production of aromatic hydrocarbons incorporating by-product utilisation |
| AU601776B2 (en) * | 1986-11-06 | 1990-09-20 | British Petroleum Company Plc, The | Process for the production of aromatic hydrocarbons incorporating by-product utilisation |
| US9938217B2 (en) | 2016-07-01 | 2018-04-10 | Res Usa, Llc | Fluidized bed membrane reactor |
| US9981896B2 (en) | 2016-07-01 | 2018-05-29 | Res Usa, Llc | Conversion of methane to dimethyl ether |
| US10189763B2 (en) | 2016-07-01 | 2019-01-29 | Res Usa, Llc | Reduction of greenhouse gas emission |
Also Published As
| Publication number | Publication date |
|---|---|
| NL7803707A (en) | 1979-10-09 |
| AU527900B2 (en) | 1983-03-31 |
| AU4576879A (en) | 1979-10-11 |
| NZ190105A (en) | 1981-07-13 |
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