US2766179A

US2766179A - Hydrocarbon conversion process

Info

Publication number: US2766179A
Application number: US426958A
Authority: US
Inventors: Ellsworth R Fenske; Clarence G Gerhold
Original assignee: Universal Oil Products Co
Current assignee: Universal Oil Products Co
Priority date: 1954-05-03
Filing date: 1954-05-03
Publication date: 1956-10-09
Anticipated expiration: 1973-10-09

Description

Oct. 9, 1956 E. R. FENsKE ETAL HYOROOARBON CONVERSION PROCESS Filed May 5,\ 1954 Nk /w A from/E V5.-

HvnnocoN coNvnnsioN Pno'cnss Ellsworth R. Fenske, Lyons, and Clarence Gerhold, Riverside, El., assignors to Universal Oil Products Company, Des Plaines, lll., a corporation of Delaware Application May 3, 1954, Serial No. 426,958

12 Claims. (Cl. 19o-28) This invention relates to a process for producing high octane gasoline and in particular relates to a combination process including purification and reforming of a contaminated gasoline or naphtha fraction to produce a pure, stable, high octane motor fuel.

It is well known that in recent years the increased use of motor vehicles has made it necessary for higher yields of gasoline to be produced from crude oil. It is equally well known that as the technology of internal combustion engines progresses the need for higher octane gasoline becomes more acute. The need for greater quantities of gasoline has been substantially met by processes wherein fractions of the crude other than those boiling in the gasoline range are converted to gasoline, however, the conversion of other fractions into gasoline does not necessarily produce large quantities of gasoline having sufficient quality to be good motor fuels. For example, thermal cracking and catalytic cracking processes provide a means of producing gasoline from higher boiling material such as gas oil, reduced crude, etc., however, the cracking processes produce substantial quantities of unsaturated olefinic material. Although olefinic material possesses rather high octane characteristics, it is unstable in storage and tends to form undesirable gums and sludges when burned in an internal combustion engine. Cracked gasoline is an abundant source of material which, if improved by other processes, will substantially satisfy the great demand. One means of improving such a fraction is by reforming processes, wherein a combination of reactions including hydrogenation of olefins to produce more stable material, isomerization of straight chain molecules to produce more highly branched chain molecules and hence higher octane gasolines, aromatization of cycloparaiiinic, olefmic and to a lesser extent parafhnic material to produce aromatic material, which greatly improves both octane characteristics and stability, and other reactions, greatly improve the quality of the gasoline. The reforming process not only changes the characteristicsof the molecules from straight chained to branched chain Vbut redistributes the hydrogen contained in the fraction so that the unsaturated material is saturated and a great deal of the saturated material is aromatized.

One difficulty experienced in reforming gasoline fractions is that when the fraction is heated to reforming temperatures polymerization reactions occur in the heater causing carbonaceous deposits, resulting from these polymerization reactions, to be formed on the heater tubes thereby seriously impairing the heat transfer ability of the tubes, reducing efficiency and eventually causing such severe clogging that the process must be shut down in order to clean the heater. It has been found that a foremost reason for this condition is the presence of dissolved oxygen in the gasoline. Oxygen dissolved in the gasoline, which is generally due to the equilibrium established with air, in some manner promotes polymerization, with its resultant difficulties, at temperatures far below the temperature at which beneficial reforming is effected, from about 300 F. and higher. The nitrogen contained in the Patented Got. 9, i955 air that is dissolved in the charge stock, although not causing deposits in the heater, is not beneficial since it forms ammonia gas under the hydrogenating conditions of a reforming Zone and ammonia gas is frequently detrimental to catalytic activity.

Hydrocarbon fractions generally contain impurities such as oxygen-containing compounds, compounds containing co-mbined sulfur and/ or containing combined nitrogen as well as minor quantities of metallic impurities and others. In many cases the presence of combined sulfur causes diiiiculty in catalytic processes since the sulfur contained in the charge impairs catalytic activity. At the hydrogenating conditions of a reforming process the sulfur contained in the charge stock is converted to hydrogen sulfide and the catalytic material, which is usually a metal at least partially is sulfided. Except in rare cases when the metal sulde is equally as good a catalyst as the metal, the reforming activity is impaired due to the formation of the sulfide. Although the metal sulfide may be reduced by the hydrogen in the reforming zone, it may be seen that a certain proportion of the metal will be in the sulded state at all times and, in order to reduce the proportion of the metal that is in the sulfded state, higher pressures of hydrogen will be required with the resultant expense of requiring high pressure equipment. From the foregoing discussion it may readily be seen that elimination of or reduction of the amount of sulfur in a feed stock is advantageous to the process. Further reasons for eliminating sulfur from the feed stocks are that the presence of sulfur in a gasoline product causes it to be sour smelling, reduces its lead susceptibility, increases its corrosiveness, and is generally undesirable.

The present invention broadly provides a method of producing a pure, stable, high octane gasoline from contaminated and/ or unsaturated charge stocks in a manner that substantially eliminates the above difficulties. The present invention, through a series of inter-related and complementary steps, removes the oxygen from a charge stock prior to heating it and simultaneously recovers ordinarily wasted products, hydroreiines the oxygen-free fraction to convert the combined sulfur contained therein to hydrogen sulfide by utilizing the net gas make from a subsequent reforming process, separates the hydrogen sulfide from the hydrorefiner efliuent in an economical manner that does not require that the pressure elevation of the stock be radically changed and subsequently reforms the stock to produce a stable, high octane, purified gasoline and a net gas make which is utilized in prior steps of the same process.

In one embodiment the present invention relates to a process for producing pure, stable, high octane gasoline from a contaminated sulfur and oxygen-containing charge stock which comprises countercurrently contacting said charge stock with a stream of hydrogen and hydrocarboncontaining gas to remove dissolved oxygen therefrom, heating the resultant oxygen-free stream and passing said heated stream into contact with a hydrorefining catalyst at hydrorelining conditions in the presence of hydrogen, passing the effluent from said hydrorelining Zone into a receiver wherein a hydrogen sulfide-containing gas phase separates from a liquid phase, passing said liquid phase into contact with an alkaline solution to remove dissolved hydrogen sulfide therefrom, subsequently passing a substantially sulfur-free charge stock into countercurrent contact with water to remove alkaline material therefrom, passing the resultant sulfur and alkaline material free hydrocarbon into Contact with a reforming catalyst at reforming conditions in the presence of hydrogen, passing the reformed material into a high pressure receiver wherein a hydrogen-containing gas is separated from the reformed liquid, passing a portion of said hydrogen-containing gas into contact with said substantially sulfur and alkaline material free charge stock contacting said reforming catalyst, passing another portion of said hydrogen-containing gas into contact with said oxygen-free material passing into said hydroreiining zone, passing the reformed liquid from said high pressure receiver into a low pressure receiver maintained at the substantially lower pressure than said high pressure receiver wherein a hydrogen and hydrocarbon-containing gas phase separates `from a liquid gasoline phase, passing at least a portion of said hydrogen and hydrocarbon gas phase into countercurrcnt contact with said contaminated charge stool; and withdrawing said liquid gasoline phase as said stable high octane gasoline.

As hereinbefore stated the charge stock. to be converted in the present process is a light petroleum distillate preferably in the gasoline or naphtha boiling range. The material may be straight run gasoline or naphtha, natural gasoline, cracked gasoline or naphtha which may be cracked either thermally or catalytically or combinations thereof. Since it is required that a net hydrogen make is realized from the reforming step of the present operation it is generally necessary that the charge stock contain at least some saturated gasoline of either the straight run or natural variety. Mildly cracked stocks may produce suflicient hydrogen from the aromatization reactions of the reforming zone to satisfy the hydrogen requirements of the other reactions, however, since straight run gasoline generally has poor octane characteristics and is available in suliicient supply, the process will generally utilize either straight run material or a mixture of straight run and cracked gasoline as a charge stock. The present process as hereinbefore described is capable of converting charge stocks containing extremely high quantities of impurities and may be used with gasolines containing up to 3 or 4 weight percent sulfur or more when conditions are suitably adjusted.

It is recognized that the presence of dissolved oxygen in a charge stock enhances its ability to polymerize at low temperature and cause coking diliiculties in the tubes of heaters. It is also recognized that removing dissolved oxygen substantially prevents the coking. The present process provides for stripping the charge stock at low temperatures with a Waste gas from the present process containing large quantities of hydrogen and low boiling hydrocarbons. By countercurrently contacting the charge stock with the gas of the present process that is produced as the gas phase from the beforementioned low pressure receiver, a multiple advantage is gained. First, the operation of removing oxygen and also dissolved nitrogen and other gases from the charge stock is accomplished by the stripping action of a gas which is compatible with hydrocarbons, namely hydrogen and hydrocarbon gases. A second advantage is that the hydrocarbons contained in a gas stream that results from an equilibrium ash of the reformed gasoline contain substantial quantities of useful hydrocarbons in the Cr and C5 range which are recovered by being adsorbed in the charge stock. A third advantave is that the gas from the low pressure receiver is at suiiiciently high pressure to be vented through the oxygen stripper Without further additions of energy in the form of a compressor. The stripping gas and the energy required to drive it through the stripper are free, so to speak, since the only cost is for the original equipment. It is not even necessary to preheat the charge to the stripper since the stripping may be effected at ambient temperature and is preferably effected at temperatures below 200 F.

The charge stock passing from the oxygen stripping zone is now in condition to be heated Without excessive polymerization and therefore the amount of deposit forming in the heater tubes will be so slight that the length of operation of the process will be controlled by other factors than heater deposits, such as catalyst life.

The material from the oxygen stripper is heated to hydrorefining conditions, commingled with hydrogen, and

passed into contact with a hydrorening catalyst. The hydrorening reactions consist of severing the bond holding combined sulfur and/ or combined nitrogen atoms to a hydrocarbon molecule and subsequently hydrogenating both the hydrocarbon fragment and the sulfur or nitrogen fragment to form a hydrocarbon and either hydrogen sulfide or ammonia. The reaction must therefore be effected in the presence of hydrogen and at conditions favorable both for severing a bond and for hydrogenating. Since hydrogenation is an important factor it is preferable that a substantial hydrogen pressure is maintained in the reaction zone and therefore the operation is preferably effected at pressures of from about 250 p. s. i. to about 1500 p. s. i. depending upon the nature of the charge stock, the purity of the hydrogen-containing gas, the amount of impurities to be removed and other factors. The hydrorefining process must be effected at temperatures sufiicieutly high to cause the severence of bonds but is limited by the adverse effect of high temperature upon hydrogenation equilibrium and by the tendency of hydrocarbons to be destructively converted at high temperatures. The desulfurization and denitrogenation reactions have been found to be readily elfected at temperatures of from about 550 F. to about 700 F. and this is the preferred temperature range of the present process.

The hydrorefining step is effected in the presence of a catalyst which is active with regard to hydrogenating combined sulfur and combined nitrogen molecules and resistant to the products of the hydrogcnation. The catalytic material used must be one that has hydrogenating activity in the metallic state as well as in the sulfidcd state. T here are many such materials including platinum, palladium, nickel, iron, cobalt, molybdenum, tungsten, manganese, chromium and many others. These materials may be used in the form of a metal or as a compound and may be used alone or in mixtures. The catalytic material may also be used in extended surface conditions, as when combined with a suitable carrier such as silica, alumina, magnesia, zirconia, activated charcoal, combinations thereof such as silica-alumina, silica-magnesia, silica-alumina-zirconia, etc. or with a naturally occurring material such as clay, kieselguhr, pumice, etc.

One particularly suitable catalytic material which shows great resistance to sulfur and nitrogen deactivation is a composite of cobalt, molybdenumy and alumina. The combination gives results that are superior to either supported cobalt or molybdenum used alone indicating that there is a complementary elect by combining the two. 'Ihe alumina carrier may be composited with other material to give it an acid acting quality which facilitates its ability to sever bonds, such material including silica, halogen, phosphoric acid, etc. As hereinbefore stated the preferred hydrorelining catalyst of the present invention comprises a composite of alumina, cobalt, and molybdenum containing from about 0.5 to about l5 Weight percent cobalt, from about 0.5 to about 25 Weight percent molybdenum and alumina which may or may not contain combined chlorine or iiuorine in an amount of from about 0.05 Weight percent to about 8 Weight percent. The cobalt and molybdenum may be converted to the sulfide form prior to use by treating the composite with H28.

The eliiuent from the hydrorening step is passed to a receiver maintained at hydrorening pressure and reduced temperature and in the receiver a hydrogen suldecontaining gas separates from a liquid phase. The gas contains hydrogen sulde, ammonia, hydrogen and hydrocarbons and this gas may be vented or may be passed either entirely or partly into the lower portion of the oxygen stripper as a portion of the before mentioned hydrogen and hydrocarbon-containing gas.

rl`he liquid from the receiver contains large quantities of dissolved hydrogen sulde due to the high pressure maintained in the receiver. Since the subsequent reforming step to be performed is also a high pressure operation it is desirable to maintain the liquid material at high pressure thereby eliminating the need for recompressing. Ordinarily, in order to remove the dissolved hydrogen sulfide from the treated stream it is necessary to strip or fractionate the liquid and this operation necessitates a reduction in pressure to cause suthcient difference in boiling point between the components of the stream. It is also necessary to reduce the stream temperature so that the desired portion of the material is in the liquid state at fractionation pressure conditions. The present process removes dissolved hydrogen sulfide from the liquid stream without altering its pressure or temperature by countercurrently contacting the stream with an alkaline solution which reacts with the hydrogen sulfide to effect a substantially complete removal thereof.

The alkaline solution may be inorganic in nature including such materials as solutions of tripotassium phosphate, sodium hydroxide, potassium hydroxide, sodium carbonate, or other basic salts or it may be organic in nature including such material as the amines and preferably high boiling amines such as diethanol amine, triethanol amine, etc. The preferred alkaline materials are diethanol amine and tripotassium phosphate since these materials form unstable complex hydrogen sulfide compounds which may be decomposed in a zone remote from the treating zone to recover the alkaline medium for reuse and to produce a separate stream of hydrogen sulde. When a regeneratable alkaline solution is used, regeneration equipment may be associated with the process to produce a recycling stream of alkaline solution.

The alkaline material may be slightly soluble in the charge stock and it is therefore preferred, in order to prevent possible deactivation of the catalyst and also to prevent the loss of alkaline solution, to recover this dissolved alkaline solution from the purified charge. This may readily be done by countercurrently contacting the charge stock with water, in which the alkaline solution is extremely soluble. rl`he countercurrent contact with Water is also advantageous in that it removes from the liquid hydrocarbon any ammonia which was produced in the hydrorefining step and not removed in the equilibrium tiash. The countercurrent contact with water may be readily effected in the same vessel as the purification step by passing the alkaline soiution into contact with the hydrocarbon liquid at an upper intermediate portion of a contacting column to descend through the column while the water may be introduced into the upper portion of the column at a point above the point of alkaline solution introduction. The water thereby scrubs the hydrocarbon in the zone between the points of water introduction and alkaline solution introduction.

When water is harmful to the process it may be necessary to dry the liquid hydrocarbon prior to reforming. This may be done by any conventional method or combination of methods including cooling to remove Water by reducing its solubility in the hydrocarbon thereby causing phase separation from which the hydrocarbon may be withdrawn by decantation, contact with a desiccant such as silica gel, alumina or commercially available material such as Drierite, contacting with a liquid dessicant such as concentrated sulfuric acid, etc. The preferred method of drying the stream is by a combination including decantation of a separated water phase followed by contact with a bed or" solid drying material such as silica gel.

The material that is charged to the reforming stage is, as a result of the previous pretreating steps, oxygen free, sulfur free and dry. This material may be commingled with hydrogen and passed to a reforming zone which contains a reforming catalyst and is maintained at reforming conditions which are preferably at a temperature of from about 700 F. to about l200 F. and at a pressure of from about 250 p. s. i. to about 1500 p. s. i. The reforming process effects a group of desirable reactions which increase the quality of the gasoline and redistribute the hydrogen contained therein to more advantageous positions. These hereinbefore discussed reactions including aromatization of naphthenes, isomerization, aromatization of parafiins, saturation of olens and selective hydrocracking of the heavier molecules contained in the feed may be promoted by a reforming catalyst so that they may be effected at milder conditions of temperature and pressure and also so that a more selec tive product is obtained. Suitable reforming catalysts may include composites of a metal and a carrier material which may also have catalytic activity. Suitable carrier materials include silica, alumina, magnesia, zirconia, activated charcoal, etc., combinations thereof such as silicaalumina, silica-magnesia, s-ilica-alumina-Zirconia etc. or composites of a carrier with an acid acting material such as composites of alumina-chlorine, alumina-duorine, alumina-phosphoric acid, etc. These carrier materials are composited with metallic catalysts having hydrogenation activity, which may include platinum, palladium, nickel, cobalt, iron, vanadium, manganese, tungsten, molybdenum, etc., compounds of these or any combinations thereof. The preferred reforming catalyst of the present invention is a composite comprising platinum, alumina, and combined halogen and preferably containing platinum in a weight percent of from about 0.01 to about 10, combined chlorine or uorine in a weight percent of from about 0.05 to about 10 on alumina pellets or spheres which are synthetically prepared to have low impurity content and high surface area.

The reformed material is separated into a gas phase and a liquid phase by reducing the stream temperature in a high pressure receiver which is operated at substantially the same pressure as the reaction Zone. The gas phase thus obtained consists largely of hydrogen and hydrocarbons having from l to 4 carbon atoms. This gas may contain hydrogen concentrations in excess of mol percent and will usually contain from about 75 to about 90 mol percent hydrogen and is therefore extremely suitable as a source of hydrogen to hydrocarbon processing operations. The reforming gas from the high pressure receiver is largely disposed of within the process of the present invention by passing to the inlet of the reformer as the hydrogen-containing gas required therein and also to the inlet to the hydrorefining stage as the hydrogen-containing gas required therein.

The liquid product from the high pressure receiver is throttled to a lower pressure, of from about p. s. i. to about 500 p. s. i., in a second receiver herein called the low pressure receiver. In the low pressure receiver an equilibrium flash occurs and the gas phase resulting therefrom consists of hydrogen and low boiling hydrocarbons, however, in contrast to the gas phase from the high pressure receiver, the gas phase from the low pressure receiver contains substantially greater quantities of hydrocarbon and substantially less hydrogen. The quantity of gas produced in the low pressure receiver may be regulated by the pressure and temperature at which the receiver is maintained. Although a one-stage flash, such as that effected in the low pressure receiver, causes valuable hydrocarbons to enter the gas stream, these hydrocarbons are not lost since the gas phase from the low pressure receiver is used as the stripping gas in the oxygen stripping stage of the process. The dual function of removing oxygen from the charge stock and adsorbing valuable hydrocarbons from the low pressure receiver gas is effected in the oxygen stripper and as a result of the countercurrent contact maintained therein the vent gas from the oxygen stripper consists largely of oxygen, nitrogen, hydrogen and hydrocarbon gases having from l to 3 carbon atoms. The liquid phase from the low pressure receiver, when stabilized, is a stable, high quality, high octane, extremely pure gasoline.

The accompanying drawing is included to further illustrate the process of the present invention and will be described in relation to the processing of a straight run naphtha with a cobalt-molybdenum-alumina hydrorefining catalyst, an alkaline solution comprising diethanolamine and water and a reforming catalyst comprising platinum, alumina and combined halogen. It is to be understood that the specific process herein described is for the purpose of illustration and not limitation,

Straight run naphtha charge passing through line 1 is pumped by pump 2 into line 3 which discharges the naphtha into the upper portion of oxygen stripper 4. In oxygen stripper 4, which contains suitable internal devices to effect the advantageous intimate contact of a descending liquid stream and a rising gas stream such as bubble trays, seive decks, packing, etc., the charge stock is countercurrentlv and intimately contacted at ambient temperature with an ascending gas stream obtained as hereinafter described, entering the lower portion of oxygen stripper 4 through line o and comprising hydrogen and light hydrocarbons. As a result of the countercurrent Contact, dissolved oxygen, nitrogen and other gases are removed from the charge stock and pass from the upper portion of oxygen stripper flthrough line 5 as vent gas which may be vented to the atmosphere, burned as fuel or otherwise disposed of.

The naphtha charge, now free of dissolved gaseous impurities, is withdrawn from the lower portion of oxygen stripper 4 through line 7 and is pumped by pump 8 into line 9 which discharges into heater 10. Heater 10, which may be any conventional heater or heat exchanger, discharges into line 11 wherein the oxygen-free naphtha charge is commingled with a hydrogen-containing gas stream which enters line 11 through line 12. The hot commingled stream passes into the upper portion of hydroreiiner 13 wherein it is contacted with the before mentioned catalytic composite comprising cobalt, molybdenum and alumina. In the hydrorelining zone the reactions forming hydrogen sulfide from combined sulfur compounds, ammonia from combined nitrogen compounds and to some extent the adsorption of metallic impurities are effected at a temperature of from about 550 F. to about 700 F. and a pressure of from about 250 p. s. i. to about 1500 p. s. i. and the effluent stream containing substantially hydrocarbons, hydrogen sulfide and ammonia is withdrawn from hydroreiiner 13 through line 14. The effluent from the hydroreiiner passes into an intermediate portion of receiver 15 at substantially the pressure of the hydrorener and at reduced temperature, about 100 F. to 350 F., which results in the formation of a gas phase and a liquid phase. The gas phase consists largely of hydrogen, hydrogen sulfide and ammonia, the ammonia being a minor portion Since low quantities of nitrogen-containing compounds are generally found in a charge stock. The gas phase from receiver 15 is withdrawn throughline 15 and valve 17 and passes into the before mentioned line 6 which provides stripping gas to the lower portion of oxygen stripper 4. When it is .desired to remove the hydrogen sulfide from the process instead of recycling it through the oxygen stripper to be discharged with the vent gas through line 5, valve 17 may be closed and the entire gas phase from receiver 15 may be passed through line 45 and valve 45 and removed from the process. The stream may of course, be distributed so that a portion is vented and another portion is passed to the bottom of oxygen stripper 4.

The liquid portion of the hydroreiining zone effluent which contains hydrocarbon and dissolved hydrogen sultide and ammonia passes through line 13 into the lower portion of scrubber 19. In scrubber 19 the liquid is countercurrently contacted with liquid alkaline solution which reacts with the hydrogen sulfide dissolved in the hydrocarbon to form an unstable complex compound in the water phase and therefore removes hydrogen sulfide from the hydrocarbon phase. Alkaline solution is introduced into an upper intermediate portion of scrubber 19 through line 22 and descends in liquid-liquid contact with the ascending hydrocarbon stream. When the ascending hydrocarbon stream reaches an elevation higher than the inlet of line 22 it is contacted with a descending water stream entering the upper portion of scrubber 19 through line 23 and as a result of the countercurrent contact the dissolved alkaline solution and remaining ammonia from the hydroreiining step are removed. As the water from line 23 descends the column to the point where the alkaline solution from line Z2 enters the co1- umn, the water dilutes the alkaline solution and the two descend together and are collected in the lower portion of scrubber 19 eventually to be discharged from the column through line 20. It may be seen that a more concentrate-.1i alkaline solution than is desired in the scrubber should be charged to line 22 so that the resultant dilution with water will cause a solution of the proper concentration to be present in the scrubber.

The scrubbing step may be effected in two vessels, one of which contains alkaline solution and the other water. Although the use of two vessels removes the necessity of controlling concentrations, the single vessel is preferred since it reduces the amount of equipment necessary. Since the concentration of alkaline solution is not critical the less precise single vessel system is suitable.

When the preferred alkaline solution of the present invention, that is diethanol amine, is used, it may be regenerated by passing the contaminated solution in line to a fractionation zone wherein it is subjected to heat which separates the diethanol amine from the water and causes the unstable amine-hydrogen sulfide complex to dissociate. In such a regeneration zone an overhead product comprising water and H25 may be removed and a substantially pure bottoms product comprising diethanol amine may be recovered. When a regeneration step is used the diethanol amine thus recovered will be returned to scrubber 19 through the before mentioned line 22.

A purified hydrocarbon stream is withdrawn from the upper portion of scrubber 19 through line 21 and passed to a reforming stage. When the reforming catalyst is sensitive to water it may be necessary to remove the water in dryer 24. The dried, purified feed stock passes from dryer 24 through line 26 and is pumped by pump 27 into line 28 wherein the feed stock is commingled with a stream of hydrogen-containing gas entering line 28 through line 36 and valve 37. The commingled stream passes to heater 29 wherein it is heated to reforming temperatures and passes through line 30 into the upper portion of reformer 31 and into contact with reforming catalyst. In reformer 31 a catalyst bed, preferably of alumina, platinum and combined halogen, is maintained at temperatures of from about 700 F. to about l200 F. and preferably at temperatures of from about 850 F. to about 950 F., and under a pressure of from about 250 p. s. i. to about 150() p. s. i. and preferably from about 500 p. s. i. to about 800 p. s. i. As a result of the contact of the charge stock and the reforming catalyst the desired reforming reactions are effected and the effluent from the reforming zone passes from the lower portion thereof through line 32 and into an intermediate portion of high pressure receiver 33 which is maintained at substantially the same pressure as reformer 31. In high pressure receiver 33 the stream temperature is lowered and a hydrogen-containing gas phase separates from a reformed liquid phase. The hydrogen-containing gas phase consists almost exclusively of hydrogen and hydrocarbon and mostly of hydrogen having a hydrogen concentration of from about volume percent to about volume percent or more. This hydrogen rich gas passes through line 34 which discharges partially into the before mentioned line 36 passing into line 28 carrying charge stock to the reforming zone. Another portion of the gas in line 34 passes to line 35 into the before mentioned line 12 which discharges into line 11 to the inlet of the hydrorener 13. Line 47 and valve 4S are provided to vent a portion of the gas from the high pressure receiver if such venting is necessary in order to prevent a pressure buildup.

The liquid phase in high pressure .receiver 33 passes through line 38 and throttling valve 2S and is discharged into low pressure receiver 39 at a pressure substantially less than that maintained in reformer 31. As a result of the pressure reduction an equilibrium flash occurs in receiver 39 forming another gas phase and a liquid phase. The gas phase, which contains hydrogen and hydrocarbon, passes through line 40 and valve 41 into the before mentioned line 6 which discharges into the lower portion of oxygen stripper 4. When it is desired to vent a portion of the gas from low pressure receiver 39, line 42 and valve 43 are provided.

The liquid phase that collects in low pressure receiver 39 is withdrawn through line 44, stablized and ready for storage. This liquid phase is a high octane, high quality, clean, stable gasoline that is ready for marketing.

We claim as our invention:

1. A process for producing stable high octane gasoline from a contaminated sulfur and oxygen-containing charge stock which comprises countercurrently contacting said charge stock with a stream of hydrogen and hydrocarbon-containing gas, obtained as hereinafter set forth, and removing dissolved oxygen therefrom, heating the resultant oxygen-free stream and passing said heated stream into contact with a hydroretining catalyst at hydrorening conditions in the presence of hydrogen, passing the euent from said hydrorening zone into a receiver wherein a hydrogen sulfide-containing gas phase separates from a liquid phase, passing said liquid phase into countercurrent contact with an alkaline solution to remove dissolved hydrogen sulde therefrom, subsequently passing the resultant substantially sulfur-free charge stock into countercurrent contact with water to remove alkaline material therefrom, passing the resultant sulfur and alkaline material free hydrocarbon into contact with a reforming catalyst at reforming conditions in the presence of hydrogen, passing the reformed material into a high pressure receiver wherein a hydrogen-containing gas is separated from a reformed liquid, passing a portion of said hydrogen-containing gas into contact with said substantially sulfur and alkaline material free hydrocarbon contacting said reforming catalyst, passing another portion of said hydrogen-containing gas into contact with said oxygen-free stream passing into said hydrorening zone, passing the reformed liquid from said high pressure receiver into a low pressure receiver maintained at a substantially lower pressure wherein a hydrogen and hydrocarbon-containing gas phase separates from a liquid gasoline phase, passing at least a portion of said hydrogen and hydrocarbon-containing gas phase into countercurrent contact with said contaminated charge stock as aforesaid and withdrawing said liquid gasoline phase as said stable, high octane gasoline.

2. A process for producing stable, high octane gasoline which comprises passing an oxygen and sulfur-containing charge stock into countercurrent contact with a hydrogen and hydrocarbon-containing gas stream at a temperature not in excess of 200 F., heating the resultant oxygen-free charge stock and passing said heated charge stock into contact with a hydroreiining catalyst at a temperature of from about 550 F. to about 700 F. and a pressure of from about 250 p. s. i to about 1500 p. s. i. in the presence of hydrogen, passing the resultant hydroreined material into a receiver wherein a hydrogen sultide-containing gas phase separates from a liquid phase, passing said liquid phase into countercurrent contact with an alkaline solution to remove dissolved hydrogen suliide therefrom, subsequently contacting said liquid phase with water to remove alkaline material therefrom, heating the sulfur and alkaline material free liquid phase and passing the latter into Contact with a reforming catalyst at a temperature of from about 700 F. to about l200 F. and a pressure of from about 250 p. s. i. to about 1500 p. s. i in the presence of hydrogen, passing the reformed product into a high pressure receiver maintained substantially at the pressure of the reaction Zone wherein a hydrogen-containing gas phase separates from a reformed liquid phase, passing a portion of said hydrogencontaining gas phase to said reforming zone as said hydrogen, passing another portion of said hydrogen-containing gas phase to said hydroreiining zone as said hydrogen, passing the reformed liquid phase into a low pressure receiver maintained at a pressure of from about p. s. i. to about 500 p. s. i. wherein a hydrogen and hydrocarboncontaining gas phase separates from a liquid gasoline phase, passing at least a portion of said hydrogen and hydrocarbon-containing gas phase into countercurrent contact with said incoming charge stock as at least a portion of said hydrogen and hydrocarbon-containing gas stream and withdrawing said liquid gasoline phase from said low pressure receiver as a stable, high octane gasoline.

that at least a portion of said hydrogen sulfide-containing gas from said hydrorening zone receiver is passed intov countercurrent contact with the incoming charge stock as a portion of said hydrogen and hydrocarbon-containing gas stream.

4. The process of claim 1 further characterized in that the hydrogen sulfide and alkaline material free hydrorened charged stock is contacted with a desiccant prior to being contacted with reforming catalyst.

5. The process of claim l further characterized in that said hydroretined catalyst comprises a sulded composite of cobalt, molybdenum and alumina.

6. The process of claim 1 further characterized in that said reforming catalyst comprises platinum, alumina and combined halogen.

7. A process for producing stable, high octane gasoline which comprises passing an oxygen and sulfur-containing charge stock into countercurrent contact with a hydrogen and hydrocarbon-containing gas stream at a temperature not in excess of 200 F., heating the resultant oxygenfree charge stock and passing said heated charge stock into contact with a hydrorein-ing catalyst comprising cobalt, molybdenum and alumina a-t a temperature of from about 550 F. to about 700 F. and a pressure of from about 250 p. s. i. to about 1500 p. s. i. in the presence of hydrogen, passing the resultant hydrorelined material into a receiver wherein a hydrogen sulfide-containing gas phase separates from a liquid phase, passing said liquid phase into coun-tercurrent contact with a solution comprising diethanol amine and water to remove dissolved hydrogen sulde therefrom, subsequently contacting said liquid phase with water to remove alkaline material therefrom, drying the liquid phase, heating .the sulfur and alkaline material free liquid phase and passing the latter into contact with a reforming catalyst comprising platinum, alumina and combined halogen at a temperature of from about 700 F. to about 1200 F. at a pressure of from about 250 p. s. i. to about 1500 p. s. i. in the presence of hydrogen, passing the reformed product into a high pressure receiver maintained substantially at the pressure of the reaction zone wherein a hydrogen-containing gas phase separates from a reformed liquid phase, passing a portion of said hydrogen-containing gas phase to said reforming zone as said hydrogen, passing another portion of said hydrogen-containing gas phase to said hydroreiining zone as said hydrogen, passing the reformed liquid phase into a low pressure receiver maintained at a pressure of from about 100 p. s. i. to about 500 p. s. i. wherein a hydrogen and hydrocarbon-containing gas phase separates from a liquid gasoline phase, passing at least a portion of said hydrogen and hydrocarbon-containing gas phase into countercurrent contact with said incoming charge stock as at least a portion of said hydrogen and hydrocarbon-containing gas stream and withdrawing said liquid gasoline phase from said low pressure receiver as a stable, high octane gasoline.

8. The process of claim 7 further characterized in that said hydrorelining catalyst contains from Vabout 0.5 to about 15 weight percent cobalt and from about 0.5 to about 25 weight percent molybdenum.

9. The process of claim 7 further characterized in that said reforming catalyst contains from about 0.01 to about l0 Weight percent platinum and from labout 0.05 to about l() weight percent halogen.

10. A process for producing stable, high octane gasoline from a contaminated sulfur and oxygen-containing charge stock which comprises countercurrently contacting said charge stock with a stream of hydrogen yand hydrocarboncontaining gas to remove dissolved oxygen therefrom, heating the resultant oxygen-free stream and passing said heated stream into contact with a hydrorelining catalyst at hydrorening conditions in the presence of hydrogen, passing the effluent from said hydroretining zone into a receiver wherein a hydrogen sulfide-containing gas phase separates from a liquid phase, passing said liquid phase into contact with a reforming catalyst at reforming conditions in the presence of hydrogen, passing said reformed material into a high pressure receiver wherein a hydrogencontaining gas is separated from a reformed liquid, passing a portion of said hydrogen-containing gas into contact with said liquid phase contacting said reforming catalyst, passing another portion of said hydrogen-containing gas into contact with said oxygen-free stream passing into said Ihydroretining zone, passing the reformed liquid from said high pressure receiver into a low pressure receiver maintained at a substantially lower pressure wherein a hydrogen and hydrocarbon-.containing gas phase separates from a liquid gasoline phase, passing at least a portion of said hydrogen and hydrocarbon-containing gas phase into countercurrent contact with said contaminated charge 12 stock and withdrawing said liquid gasoline phase as said stable, .high octane gasoline.

l1. A process for producing high octane gasoline from light petroleum distillate contaminated with sulfur Iand dissolved oxygen, which comprises contacting the contaminated distillate with a gas stream containing hydrogen and C4 and C5 hydrocarbons to remove dissolved oxygen from the distillate and to absorb C4 -an'd C5 hydrocarbons in the distillate, thereafter heating the distillate to hydrorening temperature and contacting the heated distillate with a hydrorelining catalyst in the presence of hydrogen, separating the resultant products into a liquid phase and a gas phase containing hydrogen sulfide, reforming said liquid phase in the presence of hydrogen, separating a hydrogen-containing gas from the reformed liquid under high pressure, reducing the pressure on said reformed liquid and separating therefrom a gas phase containing hydrogen and C4 4and C5 hydrocarbons, and supplying at least a portion of said gas phase to the rst-mentioned contacting step as said gas stream for contact with the contaminated distillate therein.

12. The process of claim 11 further characterized in that separate portions of said hydrogen-containing gas separated from the reformed liquid are supplied to the hy drorening step and to the reforming step.

References Cited in the tile of this patent UNITED STATES PATENTS 2,300,877 Drennan Nov. 3, 1942 2,580,478 Stine Jan. l, 1952 2,606,141 Meyer Aug. S, 1952 2,671,754 De Rosset et al Mar. 9, 1954 2,691,623 Hartley Oct. 12, 1954

Claims

1. A PROCESS FOR PRODUCING STABLE HIGH OCTANE GASOLINE FROM A CONTAMINATED SULFUR AND OXYGEN-CONTAINING CHARGE STOCK WHICH COMPRISES COUNTERCURRENTLY CONTACTING SAID CHARGE STOCK WITH A STREAM OF HYDROGEN AND HYDROCARBON-CONTAINING GAS, OBTAINED AS HEREINAFTER SET FORTH, AND REMOVING DISSOLVED OXYGEN THEREFROM, HEATING THE RESULTANT OXYGEN-FREE STREAM AND PASSING SAID HEATED STREAM INTO CONTACT WITH A HYDROREFINING CATALYST AT HYDROREFINING CONDITIONS IN THE PRESENCE OF HYDROGEN, PASSING THE EFFLUENT FROM SAID HYDROREFINING ZONE INTO A RECEIVER WHEREIN A HYDROGEN SULFIDE-CONTAINING GAS PHASE SEPARATES FROM A LIQUID PHASE, PASSING SAID LIQUID PHASE INTO COUNTERCURRENT CONTACT WITH AN ALKALINE SOLUTION TO REMOVE DISSOLVED HYDROGEN SULFIDE THEREFROM, SUBSEQUENTLY PASSING THE RESULTANT SUBSTANTIALLY SULFUR-FREE CHARGE STOCK INTO COUNTERCURRENT CONTACT WITH WATER TO REMOVE ALKALINE MATERIAL THEREFROM, PASSING THE RESULTANT SULFUR AND ALKALINE MATERIAL FREE HYDROCARBON INTO CONTACT WITH A REFORMING CATALYST AT REFORMING CONDITIONS IN THE PRESENCE OF HYDROGEN, PASSING THE REFORMED MATERIAL INTO A HIGH PRESSURE RECEIVER WHEREIN A HYDROGEN-CONTAINING GAS IS SEPARATED FROM A REFORMED LIQUID, PASSING A PORTION OF SAID HYDROGEN-CONTAINING GAS INTO CONTACT WITH SAID SUBSTANTIALLY SULFUR AND ALKALINE MATERIAL FREE HYDROCARBON CONTACTING SAID FEFORMING CATALYST, PASSING ANOTHER PORTION OF SAID HYDROGEN-CONTAINING GAS INTO CONTACT WITH SAID OXYGEN-FREE STREAM PASSING INTO SAID HYDROREFINING ZONE, PASSING THE REFORMED LIQUID FROM SAID HIGH PRESSURE RECEIVER INTO A LOW PRESSURE RECEIVER MAINTAINED AT A SUBSTANTIALLY LOWER PRESSURE WHEREIN A HYDROGEN AND HYDROCARBON-CONTAINING GAS PHASE SEPARATES FROM A LIQUID GASOLINE PHASE, PASSING AT LEAST A PORTION OF SAID HYDROGEN AND HYDROCARBON-CONTAINING GAS PHASE INTO COUNTERCURRENT CONTACT WITH SAID CONTAMINATED CHARGE STOCK AS AFORESAID AND WITHDRAWING SAID LIQUID GASOLINE PHASE AS SAID STABLE, HIGH OCTANE GASOLINE.