US2697681A

US2697681A - Hydrocarbon conversion process

Info

Publication number: US2697681A
Application number: US215112A
Authority: US
Inventors: Maurice J Murray; Haensel Vladimir
Original assignee: Universal Oil Products Co
Current assignee: Universal Oil Products Co
Priority date: 1951-03-12
Filing date: 1951-03-12
Publication date: 1954-12-21
Anticipated expiration: 1971-12-21

Description

Dec. 21, 1954 MURRAY r 2,697,681

HYDROCARBON CONVERSION PROCESS Filed March 12, 1951 :0 Juan b 2 F 92364533: 2 E

Y I I uzjow m. mwzmouum k m Al P n mm D n u u n I b in l r mu 3 x wzimofim omm a INVENTORS: MAURICE J. MURRAY VLADIMIR HAENSEL W 7/ AT ORNEYS United States Patent HYDROCARBON CONVERSION PROCESS Maurice J. Murray, Naperville, and Vladimir Haensel,

Hinsdale, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application March 12, 1951, Serial No. 215,112

6 Claims. (Cl. 196-1411) This invention relates to :the conversion of hydrocarbons. More particularly, it is concerned with the production of motor fuel and other valuable products from crude oil by an improved process comprising a series of interdependent and interrelated steps whereby increased utilization of the combined hydrogen in the charge stock is obtained.

Present day refining processes, including integrated operations, do not obtain optimum utilization of the combined hydrogen present in crude oil. This is reflected in product distribution and quality, which, although fairly satisfactory, nevertheless fall short of the theoretical obtainable. We have invented a method of processing crude oils and converting at least a part of the higher boiling portion thereof into motor fuels and high quality intermediate oils in a manner that more efiectively utilizes the hydrogen content of the charge stock.

It is an object of this invention to produce valuable products from crude oil.

It is another object of this invention to convert crude oil to more valuable products by a process that'efliciently utilizes the combined hydrogen in the crude oil.

Another object of this invention is to produce high yields of good quality gasoline comprising primarily isoparatfins and aromatics.

Still another object is to provide a process for the production of high quality, 1'. e., substantially saturated and aromatic-free, distillate fuel utilizab'le in domestic burners and diesel engines.

A further object is to produce high yields of gasoline and fuel oils from crude oil with the production of minimum quantities of tar and residual oils.

In a broad aspect our invention relates to the distillation of crude oil to produce gasoline and reduced crude, reforming at least a portion of the gasoline to produce hydrogen, removing asphalt from the reduced crude, hydrocracking at least a portion of the asphalt-free Oll in the presence of hydrogen produced in the reforming step, and reforming at least a portion of the resultant gasoline to produce additional hydrogen for use in the hydrocracking step.

In one embodiment our invention relates to a process which comprises distilling a crude oil to separate gasoline and reduced crude, reforming at least a portion of said gasoline under conditions that result in a net production of hydrogen, deasphalting at least a portion of the reduced crude, hydrocracking at least a portion of the resultant deasphalted oil in the presence of hydrogen from the reforming step to produce gasoline, and passing at least a portion of the gasoline thus produced to said reforming step.

In a more specific embodiment our invention relates to a process which comprises distilling a crude oil under substantially atmospheric pressure to separate gasoline, at least one higher boiling fraction, and reduced crude, subjecting at least a higher boiling fraction of said gasoline to reforming in the presence of hydrogen and a platinum-alumina-combined halogen catalyst at a temperature of from about 750 F. to about 1000: F. and a pressure of from about 50 to about 1000 p. s. -1. 'to tl1ereby produce a net yield of hydrogen, deasphaltmg at least a portion of the reduced crude, hydrocracking at least a portion of the resultant deaspha'lted oil in the presence of hydrogen from the reforming step to produce gasoline, and passing at least a portion of the gasoline thus produced to said reforming step.

Our invention will be further illustrated and explained Patented Dec. 21, 1954 in connection with .the following description :of *the flow diagram shown in the figure. For purposes of simplification, the .various hydrocarbon conversion steps are shown blocked out, i. e., detailssuch .as reactors, separators, and the like, are not shown. However, 'it is .to be understood that .these .items of equipment should .be .installed wherever :necessary in .an actual process.

Crude oil is passed through line 1, pump .2, .line .3 containing valve 4, :and into distillation column .5. Gaseous hydrocarbons and .a light straight-run naphtha, with an @end hoilingzpoint of about 15.0 E, is removed overhead LfiEOIIl-LOlllfllll 5 through .line 6 containing 'valve 7. Straight-run naphtha having a boiling .point of -400" 'F.. is withdrawn throughvline ,8. Two .fuel oils of diiferent boiling ranges are withdrawn through line v9 containing valve 1'0, and through line 11 containing valve .12. .Reduced crude is withdrawn from the .bottom of distillation column 5 through line .13 containing valve 14 and is passed into vdeasphalting unit 15.

The deasphalting step of our process .may be conducted in batch pperation by mixing the reduced crude with .a suflicient volume of solvent to form two phases. Generally, the volume ratio of solvent to oil is about 410 '1 and the temperature is usually'within the range of about 60-200 F. The two phases are separated and the deasphalted oil is recovered from one phase and asphalt .is recovered from the other. The asphalt is best precipitated by use of solvents in-which the lubricating, cracking charge stock, etc., fractions are soluble, but in which the asphalt is insoluble. Because of its desirable properties, propane usually is the solvent selected.

The preferred method of operation is of the continuous type. One mode of continuous operation .is the so-called stage type. In such processes the oil .and the solvent are combined, mixed, and heated to a predetermined temperature which causes part or .all of the asphalt to form .a phase which has a low solvent content. The resultant mixture of phases is separated continuously in a settling vessel, a deasphalted oil solution is withdrawn from the top of the vessel, and an asphalt solution is withdrawn from the bottom of the vessel. In some :units provision is made for using a portion of the solvent for the purpose of washing the asphalt in order to increase the yield of good oil and to better control the melting point of the asphalt. Stage units may have two or more stages of precipitation. Conditions are then maintained in the primary stage to cause separation of the major part of the asphalt and the conditions in the succeeding stages are adjusted to throw out lower melting point asphalt and high viscosity oil.

Another mode of continuous operation is the so-called tower type. The reduced crude is introduced into a vertical baflle tower at a point approximately mid-way between the top and the bottom. Solvent is introduced into the tower near the bottom thereof. The ratio of solvent to reduced crude charged to the tower is approximately 4 to 1. The material in the bottom of the tower is maintained at a temperature of F., and the material in the top of the tower is maintained at a temperature of about F. by means of steam valves or the like. Within the tower, asphalt is precipitated from the reduced crude. The asphalt phase, being the heavier, starts for the bottom of the tower and, as it descends. it is scrubbed by the upcoming stream of propane. The more soluble oil which may have started down with the asphalt is dissolved in the propane. The oil in the propane solution moving upwardly just above the reduced crude feed point still contains some asphaltic material which precipitates as this phase moves into the higher tem perature zone near the top of the tower. The deasphalted oil-solvent phase leaves the top of the tower and is passed into a propane evaporator, wherein the major proportion of the propane is removed, condensed. and returned to the tower. The asphalt phase is withdrawn from the tower, is heated, and flashed to remove the propane. The propane is recovered and returned to the tower. Asphalt is rem ved from the system through line 16 containing valve 17.

Substantially propane-free deasphalted oil is removed from the deasphalting section of our process through line 18, containing valve 19, is joined by a stream of recycle hydrogen, prepared as hereinafter described, flowing through line 20-containing valve 21, and the combined streams are passed into heater 22. The combined stream is heated to the desired reaction temperature, and is withdrawn from heater 22 through line 23 and is introduced into hydrocracking zone 24.

A suitable hydrocracking catalyst, such as 0.5-15% nickel, 4-20% molybdenum, 0.115% platinum, palladium or ruthenium, or 0.5-15% tungsten on a cracking component such as silica-alumina, silica-zirconia, silicaalumina-zirconia, alumina-boria, or silica-magnesia; or nickel, cobalt, molybdena, tungsten, platinum, palladium, or ruthenium, on a base comprising alumina containing about 0.33.0% fluorine, is used in zone 24.

The conditions in the hydrocracking step of the process will vary with the particular type of catalyst employed, etc., but, in general, the temperature will be within the range of from about 500 to about 1000" F., the pressure will be from about 500 to about 1200 pounds or more, the weight hourly space velocity will be from about 0.2 to about 5, and the hydrogen to hydrocarbon molal ratio will be from about 2 to about 10 or more. Hydrocracking catalysts comprising nickel on a cracking catalyst base, such as nickel on silica-alumina, usually are very active, hence are employed at temperatures not greatly in excess of about 500 F. in order to avoid excessive gas production.

In the hydrocracking step, a high quality distillate fuel useful as domestic burner oil or as diesel fuel is produced. This oil is substantially saturated and free from aromatics. The gasoline that is produced in the hydrocracking step predominates in isoparafiins and in naphthenes. It is a particularly desirable charge stock for reforming processes wherein dehydrogenation of naphthenes is one of the predominant reactions. The final reformed gasoline then 1 contains a high proportion of isoparaflins and aromatics, both of which possess excellent antiknock characteristics as well as outstanding storage stability.

The hydrocarbons that boil above gasoline, which are herein referred to by the general term fuel oil, are withdrawn from hydrocracking step 24 through line 25 containing valve 26. The gasoline, or a higher boiling fraction thereof, is removed from hydrocracking step 24 through line 27 containing valve 28, and is combined with the straight-run naphtha withdrawn from distillation column through line 8 and pump 29, and flowing through line 30 containing valve 31. The combined stream of gasoline is commingled with a stream of recycle hydrogen flowing through line 32 containing valve 33. The commingled mixtures of gasoline and hydrogen are passed into heater 22 wherein they are heated to the desired reaction temperature, and the heated mixture is passed through line 34 into reforming step 35.

The catalytic agent utilized in the reforming, or aromatization, stage of our process may be a synthetically formed mass comprising a relatively inert support upon which is disposed from about 2% to about 50% of a promoting oxide selected from the oxides of the metals appearing at the left hand column of groups V and VI of the periodic table, and particularly those of chromium, molybdenum, tungsten, and vanadium. The relatively inert supports utilizable in the preparation of catalysts of this type include alumina, magnesia, zinc oxide, titanium oxide, bauxite, silica, fire-brick, pumice, various clays, etc., or mixtures thereof. Normally, a major proportion of the support with a relatively minor proportion of one or more of the above-mentioned promoting oxides is used, the latter being present in the composite in amounts ranging from about 2% to about or more of the total composite.

We prefer to use an aromatization or reforming catalyst that possesses some hydrocracking and isomerizing activity as well as dehydrogenation activity. This is for the reason that the straight-run gasoline, and to a smaller extent the hydrocracked gasoline, contains some high boiling normal paraflins that can best be up-graded by isomerization and by hydrocracking, i. e., splitting into two smaller molecular weight paraffins of increased octane number. A preferred catalyst that possesses these desirable types of activity comprises a platinum-aluminacombined halogen catalyst of the type described in U. S. Patent No. 2,479,109, issued August 16, 1949. We have found that catalysts of this type, especially those containing 0.051.5% platinum and about 0.1-2.0% combined fluorine and/or 0.1-4.0% combined chlorine, are

especially effective and economical in our process because of the long life they exhibit and also, as hereinbefore stated, because they promote parafiin isomerization and hydrocracking reactions as well as naphthene dehydrogenation.

The pressure at which our reforming process is conducted may range from substantially atmospheric pressure to about 1000 p. s. i. a. If a platinum-aluminacombined halogen catalyst is employed, the pressure ordinarily will range from about 50 p. s. i. a. to about 1000 p. s. i. a. If an appreciable amount of hydrocracking is desired when employing this particular type of catalyst, the pressure ordinarily will exceed about 500 pounds. On the other hand, if it is desired to obtain maximum dehydrogenation of naphthenes accompanied by very little hydrocracking, the pressure should be within the range of from about 50 to about 500 pounds. In general, the hydrogen to hydrocarbon molal ratio employed in our reforming step will be greater than about 2 to 1, the temperature ordinarily will lie within the range of from about 750 F. to about 1000 F., and the weight hourly space velocity ordinarily will lie within the range of from about 0.5 to about 6.

The efiluent from the reforming zone will be cooled and passed into a separator, from which a gaseous stream predominating in hydrogen can be recycled to the heater and to the reforming zone, and a part thereof directed to the hydrocracking zone. Reformed gasoline is withdrawn from reforming step 35 through line 36 containing valve 37.

The hydrocracking operation and the reforming operation may be conductedusing fixed beds, fluidized-fixed beds, moving beds, or fluidized beds of catalyst. In the reforming step, which ordinarily is substantially endothermic, a series of fixed beds of catalyst having interheaters therebetween may be employed.

Further features and advantages of our process will become apparent from the following example, which is given for illustrative and not for limitative purposes.

Example A Kansas crude oil having an API gravity of 38.0 is charged at the rate of 10,000 barrels per day to an atmospheric distillation column similar to column 5 shown in the figure. Some gas is removed overhead together with 480 barrels per day of IBP- F. end point light naphtha. There are withdrawn as side-cuts 2720 barrels per day of 150400 F. straight-run naphtha, 960 B./D. of kerosene, and 1,290 B./D. of gas-oil. Reduced crude is removed from the distillation column as a bottoms product at the rate of 4,550 barrels per day. The reduced crude is subjected to propane deasphalting in a tower-type operation. 3050 barrels of deasphalted o l are removed from the deasphalting unit and combined with hydrogen in such proportion that the molal ratio of hydrogen to hydrocarbons is 6 to 1. The combined stream is heated to a temperature of 545 F. and the heated mixture is passed over a bed of catalyst comprising 3% nickel on silica-alumina. The space velocity in the hydrocracking step is 1.0 and the pressure is 800 pounds. The gasoline produced in the hydrocracking step amount to 1680 barrels per day and the fuel oil, 1. e., the liquid hydrocarbons boiling above gasoline amounts to 1590 barrels per day. It will be noted that the llqllld volume percent yield based on the charge to the hydrocracking step is 107. This increase in yield is due to the great decrease in density that is effected in the molecular weight of the charging stock and to the extremely small production of catalyst carbon, methane, ethane, and propane.

T he gasoline produced in the hydrocracking step is distilled to remove the material boiling up to 150 F. and the remaining naphtha, i. e., ISO-400 F., is combined with hydrogen and the 150-400 F. straight-run naphtha and reformed in the presence of a catalyst comprising 0.3% platinum on alumina containing 0.18% combined fluorine. The operating conditions are an average catalyst temperature of 890 F., a liquid hourly space velocity of 3.5, and a pressure of 700 p. s. i. g. A 93% yield, i. e., 3800 barrels per day, of reformed gasoline having an F1+3cc. TEL/gal. octane number of 94.7 is produced in the reforming step. There is a net production of approximately 1000 cubic feet of hydrogen per barrel of hydrocarbon charge stock in the reforming step. Since .the hydrocracking step consumes only about 800 cubic feet of hydrogen per barrel of charge stock, and since the charge to the hydrocracking step is less than the charge rate to the reforming step, our process is self-sufficient in hydrogen.

The hydrocarbon products from the hydrocracking and reforming steps have low sulfur contents since the bulk of the sulfur compounds are converted to hydrogen sulfide in said steps.

It can be seen that our process produces high yields of gasoline having excellent antilcnock characteristics and outstanding storage stability (because of the absence of olefins), and distillate fuel oils that are saturated and aromatic-free. This process is able to achieve outstanding results in product distribution and quality because (a) it rejects, in the propane deasphalting step, hydrogen-deficient material that is difficult to process, that requires a disproportionately high consumption of hydrogen to upgrade, and that contains the bulk of the inorganic contaminants present in the crude oil, (b) it attains favorable hydrogen distribution by a combination of hydrocracking and reforming whereby high molecular Weight, hydrogen-poor material is converted into high quality, hydrogen-rich intermediate oils and high quality motor fuel While low quality straight-run gasoline is upgraded with concomitant production of hydrogen, (c) the hydrocracking and the reforming steps are operated with catalysts and at conditions that minimize gas formation, since the production of appreciable quantities of methane, ethane, and propane result in a large loss of hydrogen from the process.

In summary, our process:

1. Produces high yields of an excellent quality motor fuel comprising chiefly isoparafiinic and aromatic hydrocarbons and characterized by low sulfur content, high stability, and outstanding antiknock rating.

2. Produces large quantities of a high quality, substantially olefinand aromatic-free, distillate fuel.

3. Produces markedly smaller amounts of residue based on total crude than are produced in conventional crude oil conversion processes, which cannot successfully handle residual stocks, but only selected fractions of the crude.

We claim as our invention:

1. A process which comprises distilling a crude oil to separate gasoline and reduced crude, reforming at least a portion of said gasoline under conditions that result in a net production of hydrogen, deasphalting at least a portion of the reduced crude, hydrocracking at least a portion of the deasphalted oil in the presence of hydrogen from the reforming step to produce gasoline, and passing at least a portion of the gasoline thus-produced to said reforming step.

2. A process which comprises distilling a crude oil to separate gasoline, at least one high boiling fraction, and reduced crude, subjecting at least a high boiling fraction of said gasoline to catalytic reforming at conditions that result in a net production of hydrogen, deasphalting at least a portion of the reduced crude, hydrocracking at least a portion of the deasphalted oil in the presence of hydrogen from the reforming step to produce gasoline, and passing at least a portion of the gasoline thus-produced to said reforming step.

3. A process which comprises distilling crude oil under substantially atmospheric pressure to separate gasoline, at least one higher boiling fraction, and reduced crude, subjecting at least a higher boiling fraction of said gasoline to reforming in the presence of hydrogen and a platinumalumina-combined halogen catalyst at a temperature of from about 750 F. to about 1000 F. and a pressure of from about to about 1000 F. to thereby produce a net yield of hydrogen, deasphalting at least a portion of the reduced crude, hydrocracking at least a portion of the deasphalted oil in the presence of a hydrocracking catalyst and hydrogen from the reforming step to produce gasoline, and passing at least a portion of the gasoline thus produced to said reforming step.

4. The process of claim 3 further characterized in that said platinum-alumina-combined halogen catalyst comprises alumina containing 0.051.5% platinum and about 0.12.0% combined fluorine.

5. The process of claim 3 further characterized in that said platinum-alumina-combined halogen catalyst comprises alumina containing about 0.051.5% platinum and about 0.1-4.0% combined chlorine.

6. The process of claim 3 further characterized in that said hydrocracking catalyst comprises 0.515% nickel on silica-alumina.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,149,900 Pier et a1. Mar. 7, 1939 2,312,445 Ruthrufl Mar. 2, 1943 2,334,159 Friedman Nov. 9, 1943 2,377,116 Voorhies et al May 29, 1945 "479,110 Haerzsel Aug. 16, 1949

Claims

1. A PROCESS WHICH COMPRISES DISTILLING A CRUDE OIL TO SEPARATE GASOLINE AND REDCUED CRUDE, REFORMING AT LEAST A PORTION OF SAID GASOLINE UNDER CONDITIONS THAT RESULT IN A NET PRODUCTION OF HYDROGEN, DEASPHALTING AT LEAST A PORTION OF THE REDUCED CRUDE, HYDROCARACKING AT LEAST A PORTION OF THE DEASPHALTED OIL IN THE PRESENCE OF HYDROGEN FROM THE REFORMING STEP TO PRODUCE GASOLINE, AND PASSING AT LEAST A PORTION OF THE GASOLINE THUS-PRODUCED TO SAID REFORMING STEP.