US2911352A - Process for manufacture of high octane naphthas - Google Patents

Description

N0V- 3, 1959 L. A. GORETTA Erm. 2,911,352

PRocEss FOR MANUFACTURE oF HIGH ocTANE NAPHTHAS Filed oct. 31, 1957 High cfane Gasol/'ne ATTORNEY A tract phase (a portion of which is subjected to hydrogenative cracking) is essential in obtaining the 100+ United States Patent O ce r l 2911352 I Patented Nov. 3, 1959 (F-l) octane number naphtha. At the same time extraction prior to hydrodesulfurization reduces the hydrogen 2,911,352 requirements for hydrodesulfurization. The raffinate from the solvent extraction step may be catalytically PROCESS OF HIGH 5 cracked to make more high octane naphtha for gasoline blendlng, or it may be employed as a very superior blend- Louis A. Goretta, Hammond, Ind., and Marvin J. Den -ing stock for fuel oils.

Herder, Olymlfia Fields, me aSSigllOrs to Standard Oil Another aspect of the present invention concerns an ComPanys Chlcago, ma a c01'P0l'f0lfl 0f Indiana integrated process wherein crude oil is fractionated and Application October 31, 1957, serial No. 693,731 naphtha and gas oil fractions are recovered therefrom.

- The gas oil fraction is then processed in the manner indi- 7 Claims. (Cl. 208-68) cated in the preceding paragraph, i.e. it is catalytically cracked, unconverted gas oil is solvent extracted, the extract phase is hydrodesulfurized and then fractionated to 'Ihis invention relates to a process whereby hydrocar- 15 produce a lower boiling fraction (substantially all of bon oils are catalytically converted to high octane which boils between about 400 and 600 F.) and a naphthas in high yields. higher boiling fraction, the higher boiling fraction is A problem which continuously confronts petroleum catalytically cracked, and the lower boiling fraction is refiners is to produce the highest octane number naphthas hydrogenatively cracked. The naphtha fraction removed for blending into high anti-knock gasoline, and at the from the crude oil is preferably hydrodesulfurized first same time maximizing the yields of such naphthas. and is then catalytically hydroformed to improve its oc- Various processes such as catalytic cracking of gas oils, tane number and at the same time produce hydrogen. hydroforming of virgin and cracked naphthas, hydrode- A hydrogen stream is separated from the products of the sulfurization of oils, and hydrogenation of oils have been catalytic hydroforming step, and the hydrogen stream is proposed or are in actual use for the production of high employed in the hydrogenative cracking step. A portion octane naphtha fractions necessary. of this hydrogen stream from catalytic hydroforming may An object of this invention is to provide a combination also be used in the hydrodesulfurization steps. Because' vof refining processes which produces naphthas of maxithe activity of the hydrogenative-cracking catalyst bemum octane number in high yields. A further object is comes reduced when subjected to large amounts of hyto provide acombination of refining processes for convertdrogen sulfide and nitrogen compounds, it is important ing gas oil to high octane naphtha fractions in substanin this integrated process to employ the hydrogen protial yields while reducing the rates of catalyst deactivation duced from the catalytic hydroforming of a hydrodesuland coke deposition thereon that are normally encounfurized naphtha. After the hydrogen passes through the tered. A further object is to provide an integrated pehydrogenative-cracking unit it may advantageously then troleum reiining process wherein hydrogen is produced be employed in the hydrodesulfurization units. The

.and is used to maximum advantage in reducing the rate makeup hydrogen to the hydrodesulfurization units of catalyst deactivation and maximizing the octane num- (makeup hydrogen is added to compensate for that which ber of the naphtha fractions produced. Other objects is consumed in the hydrodesulfurization reaction) is thus and advantages of the invention will be apparent from the hydrogen stream which has been recovered from the the detailed description thereof. 40 products of hydrogenative cracking. This latter hydro- In one aspect of the present invention, a gas oil is gen stream has a higher HZS content than does the hycatalytically cracked to produce a high octane naphtha drogen stream recovered from the products of hydroand unconverted gas oil. The unconverted gas oil is forming.V In this manner the hydrogen suliide content separated from the high octane naphtha and the former within the hydrogenative cracking unit is maintained at is contacted with a selective solvent which preferentially 45 a low level which is beneficial to the maintenance of high extracts aromatic hydrocarbons. A hydrocarbon extract activity of the hydrogenative-cracking catalyst. phase rich in aromatic hydrocarbons and a hydrocarbon Figure 1 shows in diagrammatic form an embodiment raffinate phase lean in aromatic hydrocarbons is thereby of the present invention whereby components of crude oil produced. The hydrocarbon extract phase is then hyare converted to high octane naphtha fractions in high drodesulfurized by contact with hydrogen and a catalyst yield. Numerous pumps, heaters, and detailed features at an elevated temperature. Thereafter the hydrodesulhave been omitted for the purpose of clarity. These furized extract phase is fractionated into a lower boiling omitted features will be apparent to those skilled in the fraction, which usually boils between about 400 and 600 art.

F., and a higher boiling fraction. The lower boiling In this embodiment 30,000 barrels/day of crude oil is fraction of the hydrodesulfurized hydrocarbonextract iS charged from source 11 by way of line 12 into a crude hydrogenatively cracked by contacting it at atemperature oil fractitionation system as represented by vessel 13. of about 850 to 1000 F. and a pressure of about l000 From fractionating system 13 fixed gases are removed to 5000 p.s.i.g. with hydrogen and a dual-functioning overhead by way of line 14; 7,500 barrels/day of a "catalyst having hydrogenation and cracking properties. naphtha fraction is removed by way of line 16; about A very high octane number naphtha on the order of 12,000 barrels/day of a gas oil fraction is removed by 100-1-l (F-l) can thereby be produced. The higher boilway of line 17; and a residual oil is removed from the ing fraction of the hydrodesulfurized hydrocarbon extract bottom by way of line 18. The gas oil, which may boil makes. a superior charge stock to catalytic cracking. A within the range of about 400 or 450 to 900 F. and naphtha having an octane number above 90, e.g. 95 F-l above and in the embodiment herein boils within the isproduced therefrom. By splitting the hydrodesulfur- 65 range of 450 to 750 F., is passed by way of line 17 into ized extract at about the cut point indicated and catafurnace 19 wherein it is heated to a temperature suitable lytically cracking the higher boiling portion rather than for catalytic cracking. The heated gas oil is then passed passing the latter to the hydrogenative cracking step, by way of line 21 into a catalytic cracking unit, indicated higher octane products can be produced. Extraction of ,herein as vessel 22. The gas oil is catalytically cracked Y-the unconverted gas oil to produce an aromatics-rich exunder usual cracking conditions which may comprise a temperature of 850 to l050 F., a pressure of 5` to 50 p.s.i.g., a catalyst to oil ratio in the range of about 2:1

to 20:1 on a weight basis, a weight space velocity in Vthe y range of about 0.2 to 20 pounds of oil per pound of catalyst per hour. A silaceous cracking catalyst such as natural clay, activated natural clay, synthetic catalysts such as silica alumina, silica magnesia, silica alumina zirconia, etc. is used. Inthe embodiment shown herein, the gas oil is catalytically cracked using a silica alumina catalyst, a temperature of about 950 F. and a pressure of about 25 p.s.i.g., a catalyst to oil weight ratio of about 10, and a space velocity of about 3 pounds of oil per hour per pound of catalyst in the reactor. A conversion of about 50% of the gasoil to lower boiling products, principally high octane naphtha, is obtained. Any of the various types of commercial catalytic cracking processes such as uidzed bed, moving bed, fixed bed, etc. may be employed.

The products from the catalytic cracking step are removed and passed by way of line 23 into fractionating system indicated herein as fractionator 24. Light gases are removed from fractionator 24 by way of line 2.6 and passed to a vapor recovery means, not shown herein, for the removal of C3 and C., hydrocarbons. A naphtna fraction is removed from fractionator 24 by way of line 27. It has an octane number of approximately 95 or greater, the greater octane number being obtained at conversions of gas oil in excess of 50% or thereabouts. Unconverted gas oil, in the amount of about 6,000 barrels/ day based upon one-pass operation, is removed from fractionator 24 and passed by way of line 28 to solvent extraction vessel 29. This unconverted gas oil (commonly called catalytic cycle oil) boils within the range of about 400 to 750 or 800 F. and has an aromatics content in the neighborhood of about 50% and a rather high sulfur content. Its high content of polycyclic aromatic hydrocarbons makes yit an undesirable catalytic cracking charge stock since it is difficult to crack, gives low gasoline yields and causes the deposition of large amounts of coke upon the catalyst and leads to more rapid deactivation of the catalyst.

A typical solvent extraction with a solvent which is selective for aromatic hydrocarbons is carried out in extraction vessel 29. Selective solvents such as liquid SO2, phenol, cresol, Chlorex, furfural, etc. may be used in amounts of about 25 to 200 volume precent based upon oil in a solvent extraction process employing one or a considerable number of stages. In the embodiment shown herein liquid SO2 is employed as the selective solvent at an extraction temperature of about to 25 C., e.g. about C. and under sufficient pressure to maintain the SO2 in the liquid phase. The extraction is carried out in three stages, employing about 50 volume percent of liquid SO2 based upon oil in each stage. In the schematic diagram shown in Figure 1 liquid SO2 from source 31 is passed by Way of line 32 into the top of extraction vessel 29. The descending stream of liquid SO2 passes downwardly through the ascending stream of lighter oil in extraction unit 29 and extracts the aromatic hydrocarbons (as well as considerable amounts of sulfur compounds) from the cycle oil. The raliinate phase which consists primarily of cycle oil, which is now lean in aromatics, together with some occluded SO2 is removed from the top of extraction vessel 29. lt is then passed vby wa-y of line 33 into ash drum 34 wherein SO2 is vented from the oil. The SO2 is removed from the top of flash drum 34 and passed by way of line 36 into line 37 by which it is passed to line 32 for recycle to extraction vessel 29. The hydrocarbon rainate oil, which may vamount to 3,000 barrels/ day based upon the first pass of oil through the process, is removed from the bottom of ash drum 34 by way of line 38 and freed of residual SO2 by equipment not shown. A portion of it may be withdrawn by way of valved line 39 and used for blending in the manufacture of high quality fuel oil. The remainder is passed by way of line 41 to line 17 as a portion of the charge to the catalytic cracking step. This rainate oil is an excellent charge stock to catalytic cracking. An extract phase consisting of liquid SO2 containing dissolved cycle oil which is enriched in aromatic hydrocarbons, is removed from the bottom of extraction vessel 29 and passed by way of line 42 into flash drum 43. SO2, which is flashed from the extract phase in dash drum 43, is taken overhead and passed by way of line 44 into line 37 and then is recycled by Way of line 32 to extraction vessel 29. The aromatics-rich hydrocarbon extract phase, which boils between about 400 and 750 to 800 F. and now has an aromatics content of about is removed from the bottom of flash drum 43, freed from residual SO2 and passed by way of line 46 into furnace 47. The cycle oil extract may amount to about 3,000 barrels/day based upon the initial pass of crude oil on a once-through basis in this embodiment (all iigures presented herein concerning amounts of oil charged to various units and hydrogen consumed therein are based upon the initial charge of 30,000 barrels/day of crude oil without compensation for recycling of streams to various units).

The aromatic-rich hydrocarbon extract phase is heated in furnace 47 to about the hydrodesulfurization reaction temperature, and is then passed by way of line 48 into hydrodesulfurization unit 49. In the hydrodesulfurization unit, the hydrocarbon extract is contacted with a hydrodesulfurization catalyst at a temperature between about 550 to 850 F. with hydrogen in an amount between about. 1000 and 5000 s.c.f. per barrel of oil at a pressure between about 500 and 2000 p.s.i.g., eg. about 750 to 1500 p.s.i.g., and at a space velocity of about 0.5 to 20 volumes of oil per volume of catalyst per hour. Any of the various hydrodesulfurization catalysts such as the mixed oxides of cobalt and molybdenum supported on an alumina carrier, molybdena on alumina, nickle tungsten sulde, and in general the oxides and/ or suliides of groups 6 and/or 8 metals of the periodic table supported upon an alumina-type carrier may be employed. In the ernbodirnent illustrated herein, the aromatics-rich extract is contacted with approximately 3000 scf. of hydrogen per barrel of oil at a pressure of about 1000 p.s.i.g. and a temperature of about 750 F. while employing a space velocity of about 5 volumes of oil per hour per volume of catalyst. A cobaltoxide-molybdenurn oxide-alumina containing about 3% cobalt oxide and 9% molybdenum oxide is used. Approximately hydrodesulfurization of the cycle oil is obtained. Hydrogen consumption is about 1000 sci/barrel of charge to hydrodesulfurization unit 49. Based upon the 3,000 barrels per day of cycle oil extract obtained in the initial pass of crude oil through the process, hydrogen consumption amounts to about three million s.c.f. of hydrogen per day. Additional hydrogen requirements would occur if the cycle oil were not solvent extracted. ln addition to reducing the sulfur content of the cycle oil, some hydrogenation and a slight amount of cracking occurs so that the hydrodesulfurized oil has a somewhat lower boiling point.

The hydrodesulfurized cycle oil extract is passed by way of line 51 into means for separating it into various boiling fractions. This means is depicted here as fractionating tower 52. A hydrogen stream containing some of the H28 evolved during hydrodesulfurization is taken overhead and passed by way of line 53 into valved line 54 by which it is returned to line 46 and employed in hydrodesulfurization vessel 49. Naphtha formed during hydrodesulfurization (which may amount to about 10% of the charge to hydrodesulfurization vessel 49, i.e. about 300 barrels per day based upon the initial charge of crude oil to the process) is removed from fractionating tower 52 and sent by way of line 55 to hydroforrning. A higher boiling fraction, substantially all of which boils above about 600 F. and usually boils within the range of about 600 to 750 or 800 F., is removed from the bottom of fractionator 52 by Way of line 57. This higher boiling fraction amounts to about S00 barrels per day based upon the initial ypass of crude oil through the process. YA portion or all of it may be withdrawn by way.V of valved line 58 and employed for blending in fuel oil. Due to its reduced sulfur content and greater stability it forms a valuable component for that purpose. lBecause of its reduced sulfur content and because it has been partially hydrogenated, it may be passed from line 57 into valved line 59 and then sent to valved line 41 by which it may be recycled as a stock suitable for catalytic cracking.

A fraction of the hydrodesulfurized extract, substantially all of which boils within the range of about 400 to 600 F. is removed from fractionator 52 by way of line 61. This lower boiling fraction of the hydrodesulfurized extract oilamounts to about 1,900 barrels per day based upon the initial crude oil passed on a once-through basis through the system. This oil is passed into furnace 62 wherein it is heated to the temperature needed for its .hydrogenative cracking. The heated oil which may be at a temperature of about 600 to 900 F. is passed from the furnace by way of line 63 into hydrogenative cracking unit 64. In vessel 64 this lower boiling hydrodesulfurized extract oil is contacted withV hydrogen and a hydrogenative cracking catalyst at a temperature which is in the range of about 850 to l000 F.

The catalyst is a dual-functioning catalyst which combines hydrogenation properties and cracking. properties so as to cause hydrogenation of the extract oil and thereafter cracking of the oil. The hydrogenation components of such a catalyst may be the oxides and/or sulides of the metals of group 6 and/or 8 of the periodic table (or the metals themselves). These are supported .on a carrier having cracking properties such as natural and activated clays, synthetic catalytic cracking catalysts such as silica alumina, silica magnesia, silica alumina zirconia, or cracking bases such as HF promoted alumina. The catalyst may contain between 1 to 10%, preferably about 5% or thereabouts by weight, of the hydrogenation component supported in extended form upon the cracking component. The catalyst may be prepared by any of the conventional techniques such as by' impregnation of the support with an aqueous solution of the hydrogenation component, by precipitation of the hydrogenation com- 'ponent upon the cracking support, or by co-precipitation of the hydrogenation component with the cracking corn- -ponent. For example a silica alumina cracking catalyst "containing between 5 and 20% alumina with the remainder being silica, may be impregnated with a solution of ammonium molybdate, the impregnated catalyst dried and then calcined to convert the-ammonium molybdate to molybdenum oxide; thereby producing a catalyst containing about 5% M003. Other catalysts such as nickle on 'Vsilica alumina, iron on silica alumina, platinum on silica alumina, platinum on uorided alumina, cobalt molybdate on fluorided alumina, molybdenum oxide on luorided terrana earth, and similar dual-functioning catalyst may be employed. T his dual-functioning catalyst converts the polycyclic aromatics in the lower boiling extract oil to naphtha by hydrogenating one ring of the polycyclic, and thereafter by reason of the cracking component of the catalyst this hydrogenated ring is cracked whereupon the naphtha boiling range monocyclic aromatic is produced. AIn hydrogenative cracking vessel 64, the lower boiling ex- `tract oil is contacted with the dual-functioning catalyst at vthe defined temperature (about 950 F. in this embodiyment) and at a'pressure of about 1000 to 5000 p.s.i.g., eg. about 3000 p.s.i.g. while employing hydrogen in the amount of about 2000 to 6000 s.c.f./barrel of feed. A space velocity-of from 1 to 20, e.g. about 5 volumes of oil per hour per volume of catalyst may be used. Conversions to lower boiling products on the order of 80% 1or higher are obtained, most of it being high octane naphtha having an antiknock value such as 100 F-l or higher. Omission of the extraction step or the hydrodesulfurization step causes a drasticreduction inthe octane number of the naphtha. Omission of the hydrodesulfurization step also causes a reduction in the extent of conversion as well as causing an increase in the rate of deactivation of the catalyst. Thus these preceding steps are essential. Fractionation of the hydrodesulfurized extract so that only the dened lower boiling fraction is charged to hydrogenative cracking is also essential to the production of high antiknock naphtha. Because the naphtha produced by hydrogenative cracking of the higher boiling fraction of the hydrodesulfurized extract has been found to have anioctane number of F-l or lower, this higher boiling ,fraction is advantageously processed through the catalytic'` cracking unit wherein it yields a naphtha having an F-l octane number of or higher. In addition, this higher boiling extract fraction is much more resistant to conversionv in the hydrogenative cracking unit. Only about one-third of it is converted to lower boiling products as compared with 80% conversion of the lower boiling extracts. Its presence in the hydrogenative cracking unit 64 would thus `tend to build up. Because increased coke formation is encountered through the use of this higher boiling extract fraction, the dual-functioning catalyst would have to be regenerated more frequently. Approximately l2000 to 2500 s.c.f. of hydrogen per barrel of hydrodesulfurized extract charged to the hydrogenative cracking unit are consumed during the reaction. If the higher boiling fraction of the extract were processed through the hydrogenative cracking unit, an insuicient supply of hydrogen would exist. It would be necessary to employ generated hydrogen rather than to use the hydrogen which is produced during the hydroforming of the naphtha fraction. In the process described herein, suicient hydrogen is generated to satisfy the total requirements of the integrated reliningA scheme. In this embodiment approximately four million s.c.'f. ofhydrogen/day (based upon the initial crude oil on a once-through basis) are consumed in hydrogenative cracking unit 64. To maintain high catalyst activity, the hydrogen stream which is introducedinto vessel 64 is relatively free of H28. This hydrogen stream is one which is separated from the productsnfrom the'hydroforming of a desulfurized naphtha. The hydrogen 'stream is introduced by way of line 66 into line 61 by which it eventually reaches the hydrogenative cracking'vessel 64.

The reaction products from the hydrogenative cracking vessel 64 are removed therefrom and passed by way of line 67 to a fractionation system represented herein by fractionator 68. Unconverted extract oil is separated as a bottom stream and passed by way of line 69 back to the hydrogenative cracking vessel 64. The high octane naptha is removed as a side stream and passed by way of line 71 into line 27 where it is later blended with the other high octane naptha fractions produced to form the high octane gasoline. A hydrogen stream is removed overhead by way of line 72. Because this stream will normally have a higher HZS content than the hydrogen stream from hydroforming, it is passed to the hydrodesulfurization vessels wherein it serves as the hydrogen employed therein. If necessary, a portion of this stream may be recycled to the hydrogenative cracking vessel by way of line 73, but itis preferred not to do so. The major portion of the hydrogen stream owing in line 72 is` diverted and passed by Way of line 74 into line 54 by which it is charged to hydrodesulfurization vessel 49. The remaining portion of the hydrogen stream is passed by Way of line 75 and is employed in the hydrodesulfurization of the virgin naphtha.

The virgin naphtha removed from the crude oil in frac- ',tionatng system 13 is passed by Way of line 16 into furnace 76 wherein it is heated to the usual hydrodesulfurization temperature. The hydrogen stream in line 75 is also heated in the furnace tubes and is passed with the naphtha by way of line 77 into hydrodesulfurization unit 78. In

'silica alumina support, etc.

vof 100 to 400 p.s.i.g.

conditions and with the catalyst employed in hydrodesulfurization unit 49, except that a somewhat lower tempera- Ature on the order of about 550 to 750 F. is used. Hy-

drogen consumption amounts to about 20 to 60 s.c.f., usually about 40 s.c.f. of hydrogen/barrel of naphtha charged. On the basis of once-through processing of the initial crude oil, as hereinbefore dened, hydrogen consumption amounts toV about 300,000 s.c.f./day.

The products from hydrodesulfurization vessel 78 are passed by way of line 79 into fractionation system represented vherein by fractionator 81. A recycle hydrogen stream is removed overhead and is returned by way of line 82 to line 75. The desulfurized naphtha isremoved as a bottom stream from fractionator 81 and passed by way of line 83 through heater 84. The small amount of naphtha produced during the hydrodesulfurization of the cycle oil extract -is passed by way of line 56 into line 83. The heated naphtha is then passed by way of line 86 into hydro-forming unit 87.

In hydroforming unit 87, the octane number of the naphtha is greatly improved, e.g., it is increased from about 60 F-l up to 95 F-l or higher. In the hydroorming reaction, naphthenes are dehydrogenated to -higher octane aromatics and parains are cyclized to aromatcs also. A substantial quantity of hydrogen is 'produced per barrel of naphtha charged. This may vary from about 500 to 1200 s.c.f. of hydrogen per barrel of naphtha charged. The catalysts employed in hydroforming are those such as molybdena on alumina, chrornia on alumina, and platinum plus halogen on alumina or Of these, it is preferred to employ a platinum-typecatalyst because it produces the greatest improvement in octane number of the naphtha and also results in a higher net production of hydrogen. It is particularly preferred to employ the process known as Ultraforming since it produces highest octane numbers and maximum hydrogen production, due in part to its operation at somewhat lower pressures on the order The hydroforming reaction is carried out by contacting the naphtha with the catalyst at a temperature of about 850 to 1000 F. and a pressure of about 50 to 750 p.s.i.g. A space velocity from 0.5 to

` volumes of naphtha/hour/volume of catalyst is used.

Hydrogen is introduced to the reactor at the rate of about 1000 to 6000 scf/barrel of naphtha. In the embodiment described herein the naphtha is contacted with a platinum supported an alumina catalyst containing about 1% or even less of platinum at a temperature of about 925 F., a pressure of about 250 p.s.i.g., a space velocity of 1.5, with the introduction of about 3-4000 s.c.f. of hydrogen/barrel of naphtha charge. The octane number of the naphtha is improved from about 60 to about 98 F-1, and a net production of hydrogen in the neighborhood of about 1000 sci/barrel of naphtha charge is obtained. Based upon the amount charged in this embodiment, 7.8 million cubic feet of hydrogen/day are produced.

The reaction products from the hydroforming step are passed by way of line 88 into a fractionating system, indicated herein by fractionating tower 89, wherein various fractions are separated. High octane naphtha is removed from the bottom of fractionator 89 and passed by way of line 91 wherein it meets with the other high octane naptha fractions produced in the process. These fractions are blended with additional components to form the product high octane gasoline. A hydrogen stream is removed overhead from fractionator 89 by way of line 92. A portion of this stream is recycled to the hydroforming lprocess by way of line 92. The remainder ofthe stream is diverted and passed by way of line 93 to the hydrogenative cracking vessel 64. In startup operations it may jbe desirable to employ some of this hydrogen in the hydrodesulfurization units, but thereafter the integrated process functions best by charging the net production of hydrogen from the hydroformer directly to the furnace of the hydrogenative cracking vessel 64.

It is apparent from the foregoing description, that the process of this invention provides an integrated system for producing maximum octane number naphtha in high yields in an eicient manner which eliminates the need for using outside hydrogen, and employs hydrogen produced in the integrated process in a manner which further benefits operation of the process.

Thus having described the invention what is claimed l. A process for the manfacture yof high octane naphtha fractions which comprises fractionating crude oil to produce naphtha and gas oil fractions therefrom, catalytically hydroforming said naphtha fraction vto improve its octane number and simultaneously producel hydrogen, catalytically cracking said gas oil fraction to produce high octane naphtha and catalytic gas oil, solvent extracting said catalytic gas oil to separate an aromatics-rich hydrocarbon extract phase from-an aromatics-lean hydrocarbon ratinate phase, hydrodesulfurizing said hydrocarbon extract phase, splitting the hydrodesulfurized extract phase into a lower boiling fraction substantially all of which boils below about 600 F. and a higher boiling fraction, catalytically cracking said higher boiling fraction to produce high octane naphtha, hydrogenatively cracking said lower boiling fraction in the presence of a hydrogen stream recovered from the products of said catalytic hydroforming and in the presence of a catalyst having hydrogenation and cracking properties to produce a high octane naphtha.

2. The process of claim l wherein a hydrogen stream is separated from the products of the hydrodesulfurization step and recycled thereto, and the makeup hydrogen which is supplied to said hydrodesulfurization step is a hydrogen stream separated from the products of the hydrogenative cracking step.

3. The process of claim 1 wherein the naphtha produced during said hydrodesulfurization step is passed to said hydroforming step.

4. A process for producing high octane gasoline boiling range hydrocarbons which comprises catalytically cracking a gas oil to produce high octane naphtha and catalytic gas oil, extracting said catalytic gas oil with a solvent which preferentially extracts aromatic hydrocarbons and thereby producing a hydrocarbon extract phase rich in aromatic hydrocarbons and a hydrocarbon raffinate phase lean in aromatic hydrocarbons, hydrodesulfurizing said hydrocarbon extract phase, splitting said hydrodesulfurized hydrocarbon extract phase into a lower boiling fraction and a higher boiling fraction, `hydrogenatively cracking said lower boiling fraction by contacting it with a catalyst having hydrogenation and cracking properties in the presence of hydrogen and at a temperature of about 850 to 1000 F. and thereby producing a high octane naphtha.

5. The process of claim 4 wherein substantially all of said lower boiling hydrodesulfurized extract fraction boils between about 400 and 600 F., and wherein said higher boiling hydrodesulfurized extract is catalytically cracked.

6. A process for the manufacture of high octane naphtha fractions which comprises fractionating crude oil to produce naphtha and gas oil fractions therefrom, hydrodesulfurizing said naphtha fraction and thereafter hydroforming said hydrodesulfurized naphtha fraction to improve its octane number and simultaneously produce hydrogen, catalytically cracking said gas oil fraction to produce high octane naphtha and catalytic gas oil, solvent extracting said catalytic gas oil to separate an aromaticsrich hydrocarbon extract phase from an aromatics-lean hydrocarbon raflinate phase, charging said hydrocarbon railinate phase to the catalytic cracking step, hydrodesulfurizing said hydrocarbon extract phase, splitting the hydrodesulfurized extract phase into a lower boiling of about 400 to 600 F. and a higher boiling fraction substantiall al1 of which boils above about 600 F., charging said higher boiling fraction to said catalytic cracking step, hydrogenatively cracking said lower boiling 'fraction at a temperature between about 850 to 1000 F., a pressure between about 1000 and 5000 p.s.i.g. in the presence of hydrogen anda catalyst having hydrogenation and cracking properties and lthereby producing high octane naphtha, recovering a hydrogen stream from the productsof the hydroforming step and charging said hydrogen stream to the hydrogenative cracking step, recovering a second hydrogen stream from the products of the hydrogenative cracking step and charging portions of said second hydrogen stream to the hydrodesulfurization steps.

7. The process of claim 6 wherein said hydroforming step employs a supported platinum catalyst, an operating temperature of about 850 to l000 F. and a pressure of about 50 to 400 p.s.i.g.

References Cited in the file of this patent UNITED STATES PATENTS Laughlin Oct. 22, 1946 2,608,470 Helmers et a1. Aug. 26, 1952 2,703,308 Oblad et al Mar. 1, 1955 2,769,753 Hutchings et a1 Nov. 6, 1956

Claims (1)

1. A PROCESS FOR THE MANUFACTURE OF HIGH OCTANE NAPHTHA FRACTIONS WHICH COMPRISES FRACTIONATING CRUDE OIL TO PRODUCE NAPHTHA AND GAS OIL FRACTIONS THEREFROM, CATALYTICALLY HYDROFORMNG SAID NAPHTHA FRACTION TO IMPROVE ITS OCTANE NUMBER AND SIMULTANEOUSLY PRODUCE HYDROGEN, CATALYTICALLY CRACKING SAID GAS OIL FRACTION TO PRODUCE HIGH OCTANE NAPHTHA AND CATALYTIC GAS OIL, SOLVENT EXTRACTING SAID CATALYTIC GAS OIL TO SEPARATE AN AROMATICS-RICH-HYDROCARBON EXTRACT PHASE FROM AN AROMATIC-LEAN HYDROCARBON RAFFINATE PHASE, HYDRODESULFURIZING SAID HYDROCARBON EXTRACT PHASE, SPLITTING THE HYDRODESULFURIZED EXTRACT PHASE INTO A LOWER BOILING FRACTION SUBSTANTIALLY ALL OF WHICH BOILS BELOW ABOUT 600*F. ANDA HIGHER BOILING FRACTION, CATALYTICALLY CRACKING SAID HIGHER BOILING FRACTION TO PRODUCE HIGH OCTANE NAPHTHA, HYDROGENATIVELY CRACKING SAID LOWER BOILING FRACTION IN THE PRESENCE OF A HYDROGEN STREAM RECOVERED FROM THE PRODUCTS OF SAID CATALYTIC HYDROFORMING AND IN THE PRESENCE OF A CATALYST HAVING HYDROGENATION AND CRACKING PROPERTIES TO PRODUCE A HGH OCTANE NAPHTHA.

Images