US3214366A

US3214366A - Hydrocarbon conversion process

Info

Publication number: US3214366A
Application number: US383650A
Authority: US
Inventors: Harry M Brennan; Herder Marvin J Den
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1964-07-20
Filing date: 1964-07-20
Publication date: 1965-10-26
Anticipated expiration: 1982-10-26

Description

Oct. 26, 1965 HYDROCARBON CONVERSION PROCESS M. BRENNAN ETAL Filed July 20, 1964 Olefin F eea' /4 2 Makeup H -H YDROGRA CK 1N6 REA 0 TOR 23 i Recycle H L ighf Hydrocrac/rafe Heavy Hydrocrackafe INVENTORS. Harry M. Brennan Marvin J. Den/ferder United States Patent 3,214,366 HYDROQARBQN CONVERSION PROCESS Harry M. Brennan, Hammond, Ind., and Marvin J. Den Herder, Olympia Fields, Ill., assignors to Standard Oil fiompany, Chicago, 111., a corporation of Indiana Filed July 20, 1964, Ser. No. 383,650 15 Claims. (Cl. 208-110) This invention relates to .a hyrocar-bon conversion process and more particularly it relates to an improved method of hydrocracking a relatively high-boiling hydrocarbon feedstock to produce lower-boiling hydrocarbons boiling predominantly within the gasoline boiling range. This application is a continuation-in-part of SN. 134,030, now abandoned.

As is well known to those skilled in the art, hydrocracking is a general term applied to refining processes wherein hydrocarbon feedstocks of relatively high molecular Weight are converted to mixtures of hydrocarbons of lower molecular weights, and wherein the conversion is carried out at elevated temperature and pressure in the presence of a hydrogen-affording gas. In the hydro-cracking operation, it is, of course, desirable to increase the efficiency of the process, and one of the main objects is to obtain the maximum conversion of the high molecular weight feed to lower boiling materials, and at the same time provide a product having the desired characteristics. In hydrocracking, typically, hydrocarbon feeds such as catalytic :cycle oils and gas oils boiling in the range of about 350 F. to 1,000 F. are hydrocracked to obtain gasoline-boiling-range products and light distillates.

It has been discovered that the operation of a hydrocracking process can be improved by carrying out the conversion in the presence of a small amount of light olefin hydrocarbons, e.g., C to C olefins, and preferably, C to C olefins. According o the concept of the present invention, a relatively high boiling hydrocarbon feed is contacted with a hydrocra'clcing catalyst in the presence of hydrogen, or .a hydrogen-affording gas, under hyd-rocracking conditions and in the presence of about 0.3 to 20 mole percent of light olefins, based on feed, to increase the hydrocracking reaction rate without adversely affecting the product distribution. A concentration of 0.3 to 6 mole percent of light olefins is advantageous; a concentration of 1.5 to 4 mole percent is preferred.

In a preferred embodiment of the invention a light olefinic hydrocarbon such as a light catalytically cracked naphtha rich in C -C olefins of a C fraction thereof is added to the feedstock prior to its introduction into the hydrocracking zone to provide between 1.5 and 4 mole percent light olefin, based on feed, during the conversion. The hydrocracking process preferably is one employing a Group VIII metal hydrogenation component and a solid acidic cracking component wherein the catalyst activities are balanced to provide a high iso to normal ratio in the parafiins produced; and the hydrocra-cking conditions advantageously include a temperature between about 450 F. and 750 F., optimally, 500 F.-700 F.; and a pressure between about 200 and 2,000 p.s.i.g., optimally, 7S0l,000 p.s.i.g. Advantageously, a catalytically cracked cycle oil containing a substantial concentration of polynuclear aromatics is employed .as feed to the hydrocracker.

The present method has been found to increase the rate of the hydrocrack-in-g conversion without adversely affecting the product distribution. This enables the refiner to employ processing equipment of a smaller size; and/or to employ less severe hydrocr-acking conditions; and/ or requires a smaller catalyst charge. Further, light normal olefins which are introduced into the hydrocracking zone and similar hydrocarbons formed during the conversion 3,214,366 Patented Oct. 26, 1965 are converted to saturated, branched hydrocarbons, and the iso to normal paraffin ratio is greater than the ther modynamic equilibrium ratio. The isoparaffins formed are additional high octane gasoline components. It is believed that the olefins introduced into the hydrocracking zone form carbonium ions which occupy catalyst sites so as to promote the hydrocracking reaction, while :at the same time the olefins undergo hydrogenation and/or isomerization and are converted to isoparaffins.

The advantages of the invention are obtained to the fullest extent by injecting the light olefins to the hydrocracking reaction zone in a stagewise manner. In fixed bed or other systems Where the reactants llow through the reaction zone, olefins injected with the feed tend to be hydrogenated relatively rapidly and their valuable promotional effect dissipated. Thus, stepwise injection of the light olefins provides beneficial results. Moreover, it has been found that when an amount of light olefin exceeding upwards of about 6 mole percent is add-ed, the advantage of increased conversion deriving from the invention is lost and, as the proportion of olefins is increased, conversion tends to be decreased. Since, however, it is often advantageous in refinery operation to maximize utilization of light olefins, multiple injection of the light olefins within the limits contemplated by the invention is most beneficial.

The number of injection points and, consequently, the total amount of olefin injected, can vary according to the dimensions of the reaction vessel employed. Likewise, the injection points may be aligned longitudinally along the vessel, or they may be located at various points at the circumference.

The invention will be better understood by reference to the following description and accompanying drawing which is illustrative of a preferred hydrocracking scheme.

In the operation of the process, a selected feedstock is introduced into a reaction zone containing catalyst along with a hydrogen-affording gas such as hydrogen gas, catalytic reformer make-gas or a recycled hydrogen-rich gas from the present process. The process may be operated in the liquid phase, the vapor phase or mixed vapor-liquid phase. The catalyst system may be of the fixed-bed type,

as well as a fluidized bed or other appropriate type of system. The feedstocks employed may be derived from petroleum, shale, gilsonite or other such sources.

The feedstocks which may be satisfactorily hydrocracked in the present process may have compositions ranging from essentially all saturates to all aromatics. Saturates are hydrocracked to gasoline boiling-range parafiins containing a greater than equilibrium concentration of isoparaffins in the product, while in the case of polynuclear aromatics these are partially hydrogenated and the hydrogenated ring portion is hydrocracked to afford an alkyl substituted benzene and an isoparaflin. A

High boiling fractions of crude oil which boil up to about 1-200 F. may constitute advantageous feedstocks for the process of the invention. Most generally the feedstock will range from naphtha and kerosene through the light and heavy gas oils. The feedstock will normally lboil between about 300 F. and 1,000 F. Advantageously, the boiling range of the feedstock is about 300 F. to about 850 F. Examples of desirable feedstocks are light catalytic cycle oil having a boiling range of from about 350 F. to 650 F heavy catalytic cycle oil boiling in the range of about 500 F. to 850 F., virgin gas oil boiling from about 400 F. to 1,000 F. and coker gas oil boiling in the range of about 350 F. to 800 F.

Product yields are especially dependent upon the nature of the feedstock, the process conditions and the catalyst employed in the process. In each instance it is necessary *to correlate the aforementioned factors according to the desired product.

Normal amounts of sulfur which are found in the above-described feedstocks do not adversely affect the catalyst employed in the present invention. Desirably, nitrogen and oxygen as components of compounds in the feedstock are kept as low as possible in order to maintain a desirably long cycle life, i.e., the period of time for which the catalyst remains effective in producing the desired product. With higher nitrogen contents in the feedstock more frequent regenerations are required to maintain a suitable cycle life. The feed may contain up to about 0.1 weight percent nitrogen, but preferably is less than about 0.001 weight percent nitrogen in order to maintain a more satisfactory cycle life.

Since a number of refining streams suitable as hydrocracking feeds contain considerable amounts of nitrogen, it is highly desirable to pretreat such streams to reduce the nitrogen content thereof. Hydrogen treating processes, such as that wherein the feed is contacted with a cobalt-molybdena-on-alumina catalyst in the presence of hydrogen at elevated temperatures and pressure, are suitable for pretreating the feed.

The light olefinic hydrocarbons employed in the invention, typically, may be selected from the available light cracked gasolines and naphtha which contain light olefins in substantial amounts. Advantageously, catalytic naphtha, containing about 50 percent C -C olefins, coker gasoline containing C C hydrocarbons and substantial light olefins, or fractions of such streams can be employed as the source of light olefins. As noted above, the conversion is carried out in the presence of about 0.3 to 6 mole percent, preferably about 1.5 to 4 mole percent, of the light olefins.

The process conditions which are employed in the present invention can be selected over a relatively wide range and are correlated, according to the nature of the feedstock and of the particular catalyst employed, so as to produce either a desired conversion; i.e., as the percentage of feedstock converted to product, or a product of a desired octane number. The formation of alkylbenzenes from polynuclear aromatics is favored by higher pressures and moderate temperatures, and an increase in both of these variables has the effect of increasing the degree of conversion. Satisfactory conversions are obtained with the above described feedstocks at pressures in the range of about 200 and 2,000 p.s.i.g., and temperatures in the range of about 400 F. to 1,000 F., although pressures and temperatures outside of these ranges may be employed when utilizing certain feedstocks, particularly highly refractory feeds. Advantageonsly, pressures in the range of about 750 to 1,500 p.s.i.g., and temperatures between about 500 F. to 700 F. are employed. It may be desirable during the course of a run to in crease the temperature within the reaction zone as the catalyst deactivates in order to compensate for a drop in catalyst activity. Thus, with a fresh or newly regenerated catalyst it may be desirable to come on stream at a temperature of about 500 F. and to gradually increase the operating temperature towards about 700 F. during the course of a run. In most instances it is desirable to maintain a low operating temperature, since higher temepratures have been found to result in increased coking and increased amounts of gas formation.

The space velocity, expressed herein as liquid hourly space velocity (LHSV), in terms of volumes of oil charged to the reaction zone per hour per volume of catalyst, may range from about 0.1 to 10, normally from about 0.2 to 5, and preferably from about 0.25 and 2 LHSV. Lower space velocities tend to increase the degree of conversion.

Hydrogen is consumed in the process and it is necessary to maintain an excess of hydrogen in the reaction zone. However, the process is relatively unaffected by changes in the hydrogen-to-oil ratio within the general range of 4 operations. The hydrogen-to-oil ratio employed, desirably, is in the range of about 1,000 to 10,000 standard cubic feet of hydrogen gas per barrel of feed (s.c.f.b.) and advantageously about 2,000 to 5,000 s.c.f.b. is employed.

With a light catalytically cracked cycle oil as feed, it has been found that over wide ranges of operating conditions the products of the hydrocracking process predominantly boil within the gasoline boiling range. The dry gas make; i.e., methane through propane, generally is less than about 5 weight percent and, typically, is in the order of about 2 to 3 weight percent. Typically, the butane-pentane fraction of the product also is about 15 to 30 weight percent, with the amount produced being more dependent upon operating conditions and the nature of the feedstock. When employing a feedstock such as light catalytic cycle oil the pentane-plus to 400 F. fraction of the product generally will range upwardly from about 70 weight percent of the total converted product.

Typically, when it is desired to maximize the production of light distillates, i.e., materials boiling above the gasoline range and having an endpoint of about 550600 F. a heavy catalytic cycle oil boiling above about 600 F. is utilized as feed. The hydrocrackate is fractionated to provide a heavy bottoms fraction boiling above about 600 F. which is recycled to the hydrocracking zone. The amount of heavy hydrocarbons converted to distillates can be further increased by decreasing the conversion per pass.

The catalyst employed in the present process may be selected from the various well known hydrocracking catalysts, which typically comprise a hydrogenation component, which possesses hydrogenation-dehydrogenation activity and may exist in the form of certain hereinafterspecified metals or the oxides or sulfides thereof, and a solid acidic cracking component. Preferably, the hydrocracking catalyst further comprises an activity control-affording material which effectively balances the catalyst activities to provide a low rate of hydrogenation relative to the isomerization occurring during the over-all conversion. Such catalysts having balanced activities have been found to be capable of providing a product of suitable characteristics, such as more highly branched paraffins and better product distribution. These activity control-affording elements are normally employed in relatively small amounts, depending upon the activity of the hydrogenation component relative to that of the acidic component, and are further described hereinbelow.

The acidic cracking component of the catalyst may comprise one or more solid acidic components such as silica-alumina (naturally occurring and/ or synthetic) silica-magnesia, silica-alumina-zirconia, and the like. Also, acid-treated-aluminas, with or without halogens, such as fiuorided alumina, boria-alumina, and the heteropolyacid-treated aluminas, i.e., treated with phosphotungstic acid, phosphovanadic acid, silicotungstic acid, silicomolybdovanadic acid and the like, may be employed. However, it is critical that such materials possess substantial cracking activity in the finished catalyst composite. A preferred acidic component of the present catalyst composition is one of the commercially available synthetic silica-alumina cracking catalysts which may contain about 5 to 40 weight percent alumina. Preferably, the acidic component of the catalyst is employed as a support and it is highly porous, having a surface area of between about and 500 square meters per gram. The preparation and properties of the acidic cracking components are well-known in the art and they need not be described further herein for the purpose of the present invention. For example, see the series entitled Catalysis by Emmett (Reinhold Publishing Corporation), particularly volume VII, pp. 1-91.

Many of the well-known metallic hydrogenation catalysts may be incorporated in the present catalyst, but preferably, the metallic constituent of this component is selected from the metals of Group VIII of the Periodic Table which are known to possess satisfactory hydrogenation activities, especially nickel, platinum, cobalt and palladium, or from the metals of Group VI, especially tungsten molybdenum. The hydrogenation component of the catalyst advantageously can be incorporated into the catalyst by impregnating a porous acidic cracking component with a heat-decomposable compound of the hydrogenation metal, followed by calcining to provide a composite. Typically, a silica-alumina cracking catalyst or an acid-treated alumina base is impregnated with a solution of nickel acetate, chloroplatinic acid or the like, and then dried; followed by pelleting and calcining at an elevated temeparture (about 1,000 F.).

However, it is contemplated that the finished catalyst may also be produced by various methods such as by cogelling the various components and by other wellknown variations in catalyst preparation techniques to produce a finished catalyst having the desired properties.

The amount of the hydrogenation component incorporated in the catalyst can vary over a wide range, with the amount being selected to provied the desired catalyst activity. For example, large amounts of nickel, e.g., up to about 30 weight percent can be employed, and relatively small amounts of nickel, e.g., as little as about 0.1 weight percent is also effective with about 0.5 to weight percent nickel being preferred. Typically, about 0.1 to 2 weight percent platinum is effective in the catalyst and preferably about 0.1 to 1 weight percent platinum is employed. The amount of the hydrogenation component employed in the catalyst thus will depend upon the catalytic ability and economic factors.

Elements which have been found to be capable of providing and advantageous balance in activities between the metallic hydrogenation component and the solid acidic component include the normally solid elements of Group VIA of the Periodic Table, especially sulfur; the normally solid elements of Group VA of the Periodic Table, especially arsenic and antimony; and metals such as lead, mercury, copper, zinc, cadimum and the like, especially lead, mercury and copper. These catalyst modifying elements typically are incorporated into the catalyst during the catalyst manufacture by impregnating a composite such as nickel on silica-alumina with a solution of an organic or inorganic compound, such as triphenyl arsine, arsenic trioxide, triphenyl stibine, lead nitrate, or mercuric nitrate, and/ or by treating with sulfur compounds, such as carbon disulfide and hydrogen sulfide, which may be present in the feed or in the hydrogen. Where the composite is inpregnated with a liquid solution such as organo-metallic compound of the desired element, the liquid is evaporated to leave a deposit on the base and the impregnated deposit is then treated with hydrogen at an elevated temperature, typically about 850 F., to reduce the catalyst. However, it is also contemplated that the above elements may be introduced into the reaction zone during the on-oil period or during the other processing periods such as during the regeneration to contact the catalyst base in situ and thereby incorporate the element into the catalyst. As mentioned above only small amounts of activity control-affording elements are generally required in the catalyst. Typical- 1y about 0.1 to 5 moles of arsenic or antimony, preferably 6 readily regenerable catalyst can be employed in the process.

Turning now to the drawing, a hydrocracking feedstock such as a heavy catalytic cycle oil boiling in the range of about 550 F.650 F. and containing substantial amounts of polycyclic aromatic hydrocarbons is passed by way of line 11 into a hydrocracking reactor 12 containing a bed of arsenided nickel on silica-alumina catalyst. The catalyst contains 5 percent nickel, 2.5 percent arsenic and the silica-alumina support contains about 25 percent A1 0 Hydrogen from line 13 is commingled with the feedstock and introduced into the reactor. Make-up hydrogen may be introduced into the system by way of line 13 A catalytic debutanized naphtha having an ASTM distillation initial boiling point of 78 F. and an endpoint of 339 F., containing 8.8 weight percent C s 34.4 Weight percent C s 28.1 weight percent C s and 17.1 weight percent C s and containing 53.5 percent olefins is introduced into the reactor through line 14. Typically, about 3 weight percent naphtha, based on total feed (about 4.4 mole percent olefins) is introduced into the reactor commingled with the feed. Conditions within the hydrocracking reactor 12 include a temperature in the range of about 500 F.-700 F., a pressure in the range of 750 to 1,500 p.s.i.g., an overall liquid hourly space velocity between about 0.5 and 5 volumes of hydrocarbon per hour per volume of catalyst. The effiuent is withdrawn from the reactor 12 via line 18, cooled by passing through a heat exchanger 19 and passed by way of line 21 into a high pressure separator 22 wherein a hydrogen-rich gas is separated from the liquid hydrocrackate and passed by way of line 23 to line 13 to be recycled to the hydrocracking zone in the reactor. The hydrogen-to-hydrocarbon ratio within the reaction zone is between about 1,000 and 10,000 standard cubic feed of hydrogen per barrel of hydrocarbon. The remaining liquid hydrocrackate is then passed by way of line 24 to a separation means, such as fractionator 26, wherein it is distilled to separate out a light gaseous overhead fraction containing predominantly C through C hydrocarbons, a light isoparaffin-rich hydrocrackate fraction boiling in the range of C to 180 F. and a heavy aromatics-rich hydrocrackate fraction boiling the range of about 180 F. and 400 F. A bottoms fraction boiling above 400 F. is withdrawn via line 27 and is recycled to the hydrocracking zone by way of line 28.

The present invention will be better understood by reference to the following examples, which illustrate the beneficial effects on the operation of a hydrocracking process obtained by the addition of small amounts of light olefins to the hydrocracking reaction zone. It is to be understood that the following examples which are given for the purpose of illustration only do not serve in any way to limit the scope of the present invention.

EXAMPLE 1 A catalyst was prepared which comprised 5 weight percent nickle and 2.5 weight percent arsenic on a silicaalumina support containing about 25 weight percent alumina. In preparing the catalyst, a commercially high alumina silica-alumina cracking catalyst was impregnated with an aqueous solution of nickel acetate. The impregnated composite was dried at about 400 F., and calcined at 1,000 F. The calcined catalyst was then impregnated with a solution of triphenyl arsine in normal heptane. The heptane was evaporated and the arsenic treated catalyst was reduced in flowing hydrogen at atmospheric pressure and about 850 F.

A light catalytic cycle oil (LCCO) was hydrodesulfurized over a cobalt-molybdena catalyst to reduce the sulfur and nitrogen to 3 p.p.m. and 9 p.p.m. respectively. The estimated molecular weight of the cycle oil was about 200.

The hydrogen-treated cycle oil, together with varying amounts of pentane-2, was hydrooracked by contacting vof the varying amounts of olefins to the hydrocracking feedstock are shown below in Table I wherein the product analysis and percentage conversion of the feedstock are given. Also indicated are the iso to normal (i/n) paraffin ratios for the butane and pentane fractions of the reactor effluent.

contacting the mixture of said olefinic hydrocarbon and said feedstock in a hydrocracking reaction zone with a hydrocracking catalyst, in the presence of a hydrogenalfording gas at a temperature in the range of about 400 F. to about 1000" F. and a pressure in the range of about 200 to about 2,000 p.s.i.g., said catalyst comprising a metallic hydrogenation component containing a metal selected from the hydrogenation metals of Group VI and Group VIII of the Periodic Table and a solid acidic cracking component, the activities of said hydrogenation component and of said cracking component being balanced to provide a high iso-to-normal ratio in the paraffins produced.

Table l Wt. Percent Approx i/n Ratio Weight Percent Yields Olefin Mole Percent Example No. Based Percent LCGO on LOCO Based C4 C C -C 0 -180 180-400 400+ Converted on LOGO EXAMPLE 2 A sulfided nickel on silica-alumina catalyst was prepared by impregnating a silica-alumina cracking catalyst percent alumina) with an aqueous solution of nickel acetate. The impregnated composite was dried and calcined as described above. The final composite contained 5 weight percent nickel. Subsequently, the nickel on silicaalumina composite was sulfided by contacting it with a mixture of 92 percent hydrogen and 8 percent hydrogen sulfide at atmospheric pressure and a temperature of 750 F. A cetane feed containing 0.5 weight percent sulfur as carbon disulfide was contacted with the sulfided nickel on silica-alumina catalyst under the same conditions as described above. Varying amounts of pentane-2 were added to the feed and the results of the olefin addition are shown below in Table II.

2. The process of claim 1 wherein said catalyst further comprises a minor amount of an activity-control-afiording element effective to control the activities of said hydrogenation component and said acidic component to pro- 'vide a high iso-to-normal ratio in the paraffins produced.

F., a pressure in the range of about 200 to 2,000 p.s.i.g.,

From the above examples it is seen that small amounts of light olefins added to the hydrocracking feed resulted in a surprising increase in the degree of conversion of the high boiling feed to lower boiling hydrocarbons. It is further seen that if the olefins are present in excess amounts the conversion level is not increased and in fact, may even be lowered.

From the foregoing description of the present invention various modifications in the details of the operation of the hydrocracking process will become apparent to the skilled artisan, which modifications fall within the spirit and scope of the present invention.

What is claimed is:

1. A hydrocracking process which comprises adding an olefinic hydrocarbon having from 4 to 7 hydrocarbons per molecule to a high-boiling hydrocarbon feedstock to provide said olefinic hydrocarbon in an amount in the range of from about 0.3 to 6 mole percent, based on feed, and

a liquid hourly space velocity in the range of about 0.1 to 10 volumes of hydrocarbon per hour per volume of catalyst and a hydrogen-to-hydrocarbon ratio in the range of about 1,000 to 10,000 standard cubic feet of hydrogen per barrel of hydrocarbon, said catalyst comprising .(a) a solid acidic support having substantial cracking from the metals of Group VIII of the Periodic Table 'which are known to possess satisfactory hydrogenation activities, especially nickel, platinum, cobalt and palladium, or from the metals of Group VI, especially tungsten molybdenum. The hydrogenation component of the catalyst advantageously can be incorporated into the catalyst by impregnating a porous acidic cracking component with a heat-decomposable compound of the hydrogenation metal, followed by calcining to provide a composite. Typically, a silica-alumina cracking catalyst or an acid-treated alumina base is impregnated with a solution of nickel acetate, chloroplatinic acid or the like, and then dried; followed by pelleting and calcining at an elevated temeparture (about 1,000 F.).

The amount of the hydrogenation component incorporated in the catalyst can vary over a wide range, with the amount being selected to provied the desired catalyst activity. For example, large amounts of nickel, e.g.,

up to about weight percent can be employed, and relatively small amounts of nickel, e.g., as little as about 0.1 weight percent is also elfective with about 0.5 to 5 weight percent nickel being preferred. Typically, about 0.1 to 2 weight percent platinum is effective in the catalyst and preferably about 0.1to 1 weight percent platinum is employed. The amount of the hydrogenation component employed in the catalyst thus will depend upon the catalytic ability and economic factors.

Elements which have been found to be capable of providing and advantageous balance in activities between the metallic hydrogenation component and the solid acidic component include the normally solid elements of Group VIA of the Periodic Table, especially sulfur; the normally solid elements of Group VA of the Periodic Table, especially arsenic and antimony; and metals such as lead, mercury, copper, zinc, cadimum and the like,

especially lead, mercury and copper. These catalyst modifying elements typically are incorporated into the catalyst during the catalyst manufacture by impregnating a composite such as nickel on silica-alumina with a solution of an organic or inorganic compound, such as triphenyl arsine, arsenic trioxide, triphenyl stibine, lead.

nitrate, or mercuric nitrate, and/ or by treating with sulfur compounds, such as carbon disulfide and hydrogen sulfide, which may be present in the feed or in the hydrogen. Where the composite is impregnated with a liquid solution such as organo-metallic compound of the desired element, the liquid is evaporated to leave a deposit on the. base and the impregnated deposit is then treated with hydrogen at an elevated temperature, typically about 850 F., to reduce the catalyst. However, it is also contemplated that the above elements may be introduced into the reaction zone during the on-oil period or during the other processing periods such as during the regeneration to contact the catalyst base in situ and thereby incorporate the element into the catalyst. As mentioned above only small amounts of activity control-affording elements are generally required in the catalyst. Typically about 0.1 to 5 moles of arsenic or antimony, preferably 0.1 to 1 mole and optimally 0.25 to 0.75 mole of these elements per mole of the hydrogenation metal is employed. Likewise, about 0.03 to 5, optimally about 0.05 to 2 and preferably about 0.1 to 1 mole of the metals such 6 readily regenerable catalyst can be employed in the process.

Turning now to the drawing, a hydrocracking feedstock such as a heavy catalytic cycle oil boiling in the range of about 550 F.-650 Rand containing substantial amounts of polycyclic aromatic hydrocarbons is passed by way of line 11 into a hydrocracking reactor 12 containing a bed of arsenided nickel on silica-alumina catalyst'. The catalyst contains 5 percent nickel, 2.5 percent arsenic and the silica-alumina support contains about 25 percent A1 0 Hydrogen from line 13 is commingled with the feedstock and introduced into the reactor. Make-up hydrogen may be introduced into the system by way of line 13*. A catalytic debutanized naphtha having an ASTM distillation initial boiling point of 78 F. and an endpoint of 339 F., containing 8.8 weight percent C s 34.4 weight percent C s 28.1 weight percent C s and 17.1 weight percent 07 3 and containing 53.5 percent olefins is introduced into the reactor through line 14. Typically, about 3 weight percent naphtha, based on total feed (about 4.4 mole percent olefins) is introduced into the reactor commingled with the feed. Conditions within the hydrocracking reactor 12 include a temperature in the range of about 500 F.700 F., a pressure in the range of 750 to 1,500 p.s.i.g., an overall liquid hourly space velocity between about 0.5 and 5 volumes of hydrocarbon per hour per volume of catalyst. The efiluent is withdrawn from the reactor 12 via line 18, cooled by passing through a heat exchanger 19 and passed by way of line 21 into a high pressure separator 22 wherein a hydrogen-rich gas is separated from the liquid hydrocrackate and passed by way of line 23 to line 13 to be recycled to the hydrocracking zone in the reactor.

The hydrogen-to-hydrocarbon ratio within the reaction zone is between about 1,000 and 10,000 standard cubic feed of hydrogen per barrel of hydrocarbon. The remaining liquid hydrocrackate is then passed by way of line 24 to a separation means, such as fractionator 26, wherein it is distilled to separate out a light gaseous overhead fraction containing predominantly C through C hydrocarbons, a light isoparaffin-rich hydrocrackate fraction boiling in the range of C to 180 F. and a heavy aromatics-rich hydrocrackate fraction boiling the range of about 180 F. and 400 F. A bottoms fraction boiling above 400 F. is withdrawn via line 27 and is recycled to the hydrocracking zone by way of line 28.

The present invention will be better understood by reference to the following examples, which illustrate the beneficial effects on the operation of a hydrocracking processobtained bythe addition of small amounts of light olefins to the hydrocracking reaction zone. It is to be understood that the" following examples which are given for the purpose of illustration only do not serve in any way to limit the scope of the present invention.

'EXAMPLE 1 calcined at 1,000 F. The calcined catalyst was then as copper, lead or mercury per mole of the hydrogena- 1 impregnated with a solution of triphenyl arsine in normal heptane. The heptane was evaporated and the arsenic treated catalyst was reduced in flowing hydrogen at atmospheric pressure and about 850 F.

A light catalytic cycle oil (LCCO) was hydrodesulfurized over a cobalt-molybdena catalyst to reduce the sulfur and nitrogen to 3 ppm. and 9 p.p.m. respectively.

fication of catalyst reactivation techniques whereby a The estimated molecular weight of the cycle oil was about 200.

The hydrogen-treated cycle oil, together with varying amounts of pentane-2, was hydroeracked by contacting the hydrocarbons with the arsenided-nickel-on-silicaalumina cataylst in a reactor at 550 F., 1000 p.s.i.g., a liquid hourly space velocity of 0.5 volume of hydrocarbon per hour per volume of catalyst. Hydrogen gas was supplied to the reactor to provide a hyd-rogen-to-hydrocarbon ratio of 6,350 standard cubic feet of hydrogen per barrel of hydrocarbon. The results obtained from the addition of the varying amounts of olefins to the hydrocracking feedstock are shown below in Table I wherein the product analysis and percentage conversion of the feedstock are given. Also indicated are the iso to normal (i/n) paraffin ratios for the butane and pentane fractions of the reactor effluent.

contacting the mixture of said olefinic hydrocarbon and said feedstock in a hydrocracking reaction zone with a hydrocracking catalyst, in the presence of a hydrogenaifording gas at a temperature in the range of about 400 F. to about 1000 F. and a pressure in the range of about 200 to about 2,000 p.s.i.g., said catalyst comprising a metallic hydrogenation component containing a metal selected from the hydrogenation metals of Group VI and Group VIII of the Periodic Table and a solid acidic cracking component, the activities of said hydrogenation component and of said cracking component being balanced to provide a high iso-to-normal ratio in the parafiins produced.

Table l Wt. Percent Approx. i/n Ratio Weight Percent Yields Olefin Mole Percent Example No. Based Percent LOCO on LOCO Based C C C1-C C -180 180-400 400+ Converted on LC 00 EXAMPLE 2 2. The process of claim 1 wherein said catalyst further A sulfided nickel on silica-alumina catalyst was prepared by impregnating a silica-alumina cracking catalyst percent alumina) with an aqueous solution of nickel acetate. The impregnated composite was dried and calcined as described above. The final composite contained 5 weight percent nickel. Subsequently, the nickel on silicaalumina composite was sulfided by contacting it with a mixture of 92 percent hydrogen and 8 percent hydrogen sulfide at atmospheric pressure and a temperature of 750 F. A cetane feed containing 0.5 weight percent sulfur as carbon disulfide was contacted with the sulfided nickel on silica-alumina catalyst under the same conditions as described above. Varying amounts of pentane-Z were added to the feed and the results of the olefin addition are shown below in Table II.

comprises a minor amount of an activity-control-affording element effective to control the activities of said hydrogenation component and said acidic component to provide a high iso-to-normal ratio in the paraffins produced.

3. A hydrocracking process which comprises adding an olefinic hydrocarbon having from 4 to 7 carbon atoms per molecule to a hydrocarbon feedstock boiling in the range of about 350 F. to about 850 F. to provide said olefinic hydrocarbon in an amount in the range of about 0.3 to 6 mole percent, based on feed, and contacting the mixture of said olefinic hydrocarbon and said feedstock in a hydrocracking reaction zone with a hydrocracking catalyst in the presence of a hydrogen-affording gas at a temperature in the range of about 450 F. to about 750 F., a pressure in the range of about 200 to 2,000 p.s.i.g.,

What is claimed is:

a liquid hourly space velocity in the range of about 0.1 to 10 volumes of hydrocarbon per hour per volume of catalyst and a hydrogen-to-hydrocarbon ratio in the range of about 1,000 to 10,000 standard cubic feet of hydrogen per barrel of hydrocarbon, said catalyst comprising (a) a solid acidic support having substantial cracking activity, and (b) a metallic hydrogenation component comprising a metal selected from the group consisting of the hydrogenation metals of Group VI and Group VIII of the Periodic Table and a minor amount, effective to provide a high iso-to-normal ratio in the parafiins produced, of an activity-control-affording element selected from the group consisting of sulfur, lead, mercury, copper, arsenic and antimony.

4. The process of claim 3 wherein said olefinic hydrocarbon is added to said feedstock prior to its introduction into said reaction zone.

5. The process of claim 1 wherein the addition of said 9 olefinic hydrocarbon to said feedstock is made in said reaction zone at at least one point.

6. The process of claim 1 wherein said olefinic hydrocarbon is added to provide an amount of about 1.5 to 4 mole percent, based on said feedstock.

7. The process of claim 3 wherein said olefinic hydrocarbon has from 5 to 6 carbon atoms per molecule.

8. The process of claim 3 wherein said feedstock is a catalytic cycle oil substantially boiling in the range of about 350 F. to about 850 F.

9. The process of claim 3 wherein said olefinic hydrocarbon is provided by a catalytic naphtha hydrocarbon containing substantial C and C olefins.

10. The process of claim 3 wherein said catalyst comprises a sulfided nickel on silica-alumina cracking support.

11. The process of claim 3 wherein said catalyst comprises an arsenided nickel on silica-alumina cracking support.

12. The process of claim 3 wherein the addition of said olefinic hydrocarbon to said feedstock is made in said reaction zone at at least one point.

13. The process of claim 3 wherein said hydrogenation metal is a Group VIII metal and said activity-controlatfording element is sulfur, said sulfur being present in an amount from about 0.1 to 1 mole per mole of said Group VIII metal.

14. The process of claim 3 wherein said hydrogenation metal is a Group VIII metal and said activity-controlaflording element is arsenic, said arsenic being present in an amount from about 0.1 to 1 mole per mole of said Group VIII metal.

15. The process of claim 3 wherein said olefinic hydrocarbon is added to provide an amount of 1.5 to 4 mole percent, based on said feedstock.

References Cited by the Examiner UNITED STATES PATENTS 2,280,258 4/42 Pier 208-108 ALPHONSO D. SULLIVAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,214,366 October 26, 1965 Harry M. Brennan et aln It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 36, for "0" read n to line 48, for "of" read or column 5, line 5, before "molybdenum" insert and line 14, for "temeparture" read temperature line 22, for "provied" read provide M line 34, for "and" read an line 40, for "cadimum" read cadmium same column 5, line 50, for "inpregnated" read impregnated column 6, line 43, after "boiling" insert in a Signed and sealed this 12th day of July 1966 (SEAL) Attest:

ERNEST w. SWIDER EDWARD J. BRENNER Athcsting Officer Commissioner of Patents

Claims

1. A HYDROCRACKING PROCESS WHICH COMPRISES ADDING AN OLEFINIC HYDROCARBON HAVING FROM 4 TO 7 HYDROCARBONS PER MOLECULE TO A HIGH-BOILING HYDROCARBON FEEDSTOCK TO PROVIDE SAID OLEFINIC HYDROCARBON IN AN AMOUNT IN THE RANGE OF FROM ABOUT 0.3 TO 6 MOLE PERCENT, BASED ON FEED, AND CONTACTING THE MIXTURE OF SAID OLEFINIC HYDROCARBON AND SAID FEEDSTOCK IN A HYDROCRACKING REACTION ZONE WITH A HYDROCRACKING CATALYST, IN THE PRESENCE OF A HYDROGENAFFORDING GAS AT A TEMPERATURE IN THE RANGE OF ABOUT 400* F. TO ABOUT 1000*F. AND A PRESSURE IN THE RANGE OF ABOUT 200 TO ABOUT 2,000 P.S.I.G., SAID CATALYST COMPRISING A METALLIC HYDROGENTAION COMPONENT CONTAINING A METAL SELECTED FROM THE HYDROGENATION METALS OF GROUP VI AND GROUP VII OF THE PERIODIC TABLE AND A SOLID ACIDIC CRACKING COMPONENT, THE ACTIVITIES OF SAID HYDROGENATION COMPONENT AND OF SAID CRACKING COMPONENT BEING BALANCED TO PROVIDE A HIGH ISO-TO NORMAL RATIO IN THE PARAFFINS PRODUCED.