US3180817A

US3180817A - Two stage hydrocarbon conversion process with hydrocracking of the residual oil fromthe second stage, in the first stage

Info

Publication number: US3180817A
Application number: US241849A
Authority: US
Inventors: William H Claussen; William J Rossi
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1962-12-03
Filing date: 1962-12-03
Publication date: 1965-04-27
Anticipated expiration: 1982-04-27

Description

3,180,817 TWO STAGE HYDROCARBON CONVERSION PROCESS WITH HYDROGRACKING April 27, 1965 w. H. CLAUSSEN ETAL OF THE RESIDUAL OIL FROM THE SECOND STAGE,

THE FIRST STAGE Filed Dec. 3, 1962 3 MN :.omm \w w. 3 2 W ud w- W. A r m S N w 85 3755 A m omm com .2 a Q \h a d v wzoN w 0223 522: u 2 o k N 2 h .oom ..o2 a 2 w 2 a N: hrofi o 2 w. m N o ATTORNEYS fi aip mZON United States Patent M INTRODUCTION This invention relates to a hydrocarbon conversion process, more particularly to a hydrocarbon conversion process for converting petroleum distillates and residual into various valuable products, and still more particularly to a catalytic conversion process capable of producing middle distillates, heavy gasoline and light gasoline.

PRIOR ART HYDROCRACKING OF HYDRO-CAR- BON FEEDS TO PRODUCE MIDDLE DISTIL- LATES AND GASOLINE, AND PROBLEMS IN- VOLVED A. Nitrogen content 0 feed-It is Well known that nitrogen in a hydrocarbon feed is deleterious to certain hydrocracking catalysts, particularly highly acidic hydrocracking catalysts, and that, in order to provide a prac tical process for producing gasoline from a feed containing substantial amounts of nitrogen, a first stage catalyst relatively insensitive to nitrogen poisoning and having no more than Weak acidity has been necessary. However, such catalysts having no more than weak acidity frequently result in the production of substantial quantities of middle distillates, heavy gasoline and even heavier materials, although they do produce some light gasoline.

B. Ratio of lira-C to normal-C product.It is well known that a high iso-C, to normal-C product from a hydrocracking zone is highly desirable. Isobutane, for example, is a valuable product for use in motor gasoline blending, whereas normal butane is less valuable. A low iso-C, to normal-C product ratio has been a disadvantage of many prior art processes.

C. Parafiinicity of unconverted bottoms fraction recycled to react0r.lt is well known that various prior art catalysts, particularly catalysts of extremely low activity which are useful in the production of middle distillates and catalysts of extremely high activity which are useful in the production of gasoline, produce an unconverted bottoms fraction having a high content of normal paraffins. It is known that these normal parafiins are deleterious to the hydrocracking operation because they are extremely refractory to further hydrocracking and therefore, particularly where high middle distillate production is desired, as a practical matter, cannot be recycled. It would be desirable if a two-stage process were available for producing middle distillates, light gasoline and heavy gasoline in both stages without producing a first stage bottoms product having a normal paraffin content too high to permit a practical recycle thereof to the first stage.

D. Regenerati0n.-It is known that many prior art hydrocracking catalysts lose a great deal of their fresh catalyst activity upon regeneration, and it would be very desirable if the catalysts used in processes for meeting the foregoing prior art problems were regenerable.

OBJECTS In view of the foregoing, it is an object of the invention to provide a two-stage process using selected catalysts, capable of converting both hydrocarbon feed stocks that 3,180,817 Patented Apr. 27, 1965 have a high nitrogen content and those that have been denitrified, to produce middle distillates, heavy gasoline and light gasoline in' large quantities, while minimizing light gas production, at reasonable starting and operating temperatures.

' It is a further object of the present invention to provide such a process and catalysts wherein the unconverted bottoms fraction from the first stage has a sufficiently low content of normal parafiins to permit recycling a selected portion of this fraction to the first stage reactor in sustained recycle operation, to increase the overall yield of gasoline.

It is a further object of the present invention to provide such a process wherein the catalysts in each stage may be regenerated to reimpart to them a substantial portion of their original fresh activity.

DRAWING The invention Will best be understood, and further objects and advantages thereof will be apparent, from the following description when read in conjunction with the accompanying drawing which is a diagrammatic illustration of process units and flow paths suitable for carrying out the process of the invention.

STATEMENT OF INVENTION In accordance with the present invention, there is provided a process for producing gasoline and middle distillates from a hydrocarbon feed selected from the group consisting of petroleum distillates boiling from 650 to 1100 F. and petroleum residua boiling above 650 F., which comprises contacting said feed and from 1000 to 10,000 s.c.f. of hydrogen per barrel of said feed in a first conversion zone at a temperature of from 500 to 950 F., a pressure above 500 p.s.i.g. and an LHSV of 0.1 to 4.0 with a catalyst comprising at least one hydrogenating component selected from the Group VI metals and compounds of Group VI metals and at least one hydrogenating component selected from the Group VIII metals and compounds of Group VIII metals on a catalyst support comprising silica-magnesia, recovering from the efliuent from said first conversion zone a middle distillate product, a heavy gasoline product and a light gasoline product, hydrocracking in a second conversion zone in the presence of an active acidic hydrocracking catalyst a portion of the eifiuent from said first conversion zone boiling above about 650 F., and recovering from said second conversion zone a middle distillate product, a heavy gasoline product and a light gasoline product.

Further in accordance with the present'inventiomthere is provided a process 'for producing gasoline and middle distillates which comprises converting a heavy gas oil feed boiling above about 650 F. in a first conversion zone in the presence of a catalyst comprising nickel and tungsten on a silica-magnesia support at a temperature of from 500 to :950 F., a pressure above 500 psig. and

an LHSV of from 0.4 to 2.0, to a total product contain- 7 ing above 60 volume percent, based on feed converted, of 320 to 650 F. middle distillate, separating said total product into fractions including a middle distillate fraction and a gasoline fraction, recovering said middle distillate and gasoline fractions as products, hydrocracking in a second conversion zone in the presence of an active acidic hydrocracking catalyst a portioh 'of the effluent from said first conversion zone boiling above about 650 F., recovering a gasoline product from said second conversion zone, and recycling to said first conversion zone at least a portion of the effluent from said first conversion zone boiling above about 650 F.

Still further in accordance with the present invention, there is provided a process for converting a nitrogen containing hydrocarbon feed selected from the group consisting of petroleum distillates boiling from 650 F. to 1100 F. and petroleum residua boiling above 650 P. which comprises concurrently hydrofining and hydrocracking said feed by contacting said feed in a first stage in the presence of from 1000 to 10,000 s.c.f. of hydrogen per barrel of said feed and in the presence of a catalyst comprising at least one hydrogenating component selected from the group consisting of Group VI metals and compounds thereof and at least one hydrogenating component selected from the group consisting of Group VIII metals and compounds thereof on a silica-magnesia catalyst support at a temperature of 500 to 950 F., a pressure above 500 p.s.i.g. and an LHSV of from 0.1 to 4.0, hydrocracking in a second stage in the presence of an active acidic hydrocracking catalyst at least a substantial portion of the liquid efiluent from said first stage boiling above about 650 F., recovering a gasoline product from said second stage, and recycling to said first stage at least a portion of the efiluent from said first stage boiling above about 650 F., and recycling to said first stage at least a portion of the effiuent from said second stage boiling above about 650 F.

Still further in accordance with the present invention, there is provided a process as aforesaid wherein at least two reactors are used in said first conversion zone, each containing said silica-magnesia supported catalyst, and wherein said reactors are so arranged that they can be switched from parallel, for maximizing middle distillate production, to series, for maximizing either gasoline or middle distillate production, whereby the ratio of middle distillate product to gasoline product can be varied.

HYDROCARBON FEEDS SUITABLE FOR USE IN THE PROCESS OF THE PRESENT INVENTION Suitable feeds for use in the process of the present invention are petroleum distillates boiling from 650 to 1100 F., and petroleum residua boiling above 650 F., and mixtures of the foregoing. Heavy gas oils and catalytic cycle oils are excellent feeds to the process as well as conventional FCC feeds and portions thereof. Residual feeds may include Minas and other parafiinic-type residua.

The present process is particularly capable of producing middle distillates, including jet fuels, which are exceptionally high in naphthene content and low in aro matic content (therefore having high smoke points) and low in normal paraffin content (therefore having low freeze points). The feed to the present process, with an initial boiling point above 650 F., is converted directly to a synthetic material, i.e., one boiling below the initial boiling point of the feed, which is a preferred jet fuel or middle distillate having high naphthene content, low normal paraffin content and therefore low freeze point, and low aromatic content and therefore exceptionally high smoke point. It has been found that feeds having lower initial boiling points, for example around 300 to 400 F., tend to produce excessive quantities of nonsynthetic products having high aromatics content and therefore exceptionally low smoke points, although the freeze point may be satisfactory. Such a nonsynthetic product also tends to have a high pour point.

FIRST CONVERSION ZONE IN PROCESS OF PRES- ENT INVENTION, AND NITROGEN CONTENT OF FEED THERETO It has been found that the silica-magnesia supported hydrocracking catalyst in the first conversion zone of the process of the present invention is relatively nitrogen insensitive, compared with conventional acidic hydrocracking catalysts such as nickel sulfide on silica-alumina. Accordingly, the nitrogen content of the feed used in the process of the present invention may be relatively high, and excellent hydrocracking results still may be obtained in said conversion zone at reasonable temperatures, without the necessity for rapidly raising the temperature to maintain conversion as is necessary when hydrocracking a high nitrogen content feed over a conventional acidic hydrocracking catalyst such as nickel sulfide on silicaalumina. Although high nitrogen content feeds can be tolerated by said first conversion zone hydrocracking catalyst, it will be noted that said catalyst also is an excellent hydrodenitrification catalyst, and is efficient in concurrently hydrofining as well as in hydrocracking the feed. Nevertheless, the process of the present invention may be rendered even more efiicient if the feed either is low in nitrogen content or first is hydrofined by conventional methods prior to being hydrocracked in said first conversion zone in accordance with the process of the present invention. And in certain applications a conventional hydrofining zone following said first conversion zone is desirable; as will be discussed below, in one embodiment of the present invention, wherein very heavy feeds, for example propane deasphalted residua, are used, the feed may be processed in three stages; in the first stage, the feed may be concurrently hydrocracked and denitrified to a large extent over a silica-magnesia supported catalyst, following which a portion of the eflluent from the first stage may be further denitrified in a second stage before being hydrocracked over an acidic hydrocracking catalyst in a third stage.

Generally speaking, it is possible to operate the first conversion zone in the process of the present invention at slightly lower temperatures when the feed has a low nitrogen content, for example from 0 to 10 ppm. total nitrogen, than temperatures that are necessary for the same conversion when the feed hasa high nitrogen content, for example from 10 to 1000 ppm. total nitrogen. However, even feeds containing considerably higher levels of nitrogen than 1000 ppm. total nitrogen may be satisfactorily converted in the process of the present invention to valuable products, contrary to conventional prior art processes wherein acidic hydrocracking catalysts, such as nickel sulfide on silica-alumina, are used. In such conventional processes, it is impossible as a practical matter to use feeds with such high nitrogen contents.

The catalyst in the first conversion zone in the process of the present invention is capable of concurrently accomplishing both denitrification and hydrocracking. The hydrocracking facilitates the concurrent denitrification because, upon the breaking of carbon-to-carbon bonds, nitrogen is more easily removed. At higher levels of cracking conversion, somewhat higher pressures may be desired to counteract catalyst fouling and deactivation.

The nitrogen compounds tend to concentrate in the heavier portions of the feed; accordingly, such heavier portions are more difiicult to denitrify. However, it will be noted from the foregoing that such heavier portions also are easier to crack.

OPERATING CONDITIONS IN FIRST CONVERSION ZONE The first conversion zone of the process of the present invention, which contains a silica-magnesia supported catalyst, discussed below, is operated at combinations of conditions selected from Within the varying ranges that will produce the desired degree of hydrocracking: a temperature of about 500 to 950 F., preferably 650 to 850 F.; a hydrogen partial pressure of 500 to 3500 p.s.i.g., preferably 1000 to 2500 p.s.i.g.; and an LHSV of from about 0.1 to 4.0, preferably 0.4 to 2.0. The hydrogen flow to said conversion zone is from 1000 to 10,000 s.c.f. per barrel of feed, and preferably 2500 to 8000 s.c.f. per barrel of feed. The higher hydrogen partial pressures, particularly with unrefined feeds, give lower catalyst fouling rates and therefore for longer catalyst lives it is preferable to operate above 2000 p.s.i.g. In general, the hydrogen partial pressure will depend upon a number of factors, including type of feed stock and nitrogen content thereof, degree of denitrification re- CATALYST IN FIRST CONVERSION GROUP A. Composition of catalyst-It is essential that the catalyst in the first conversion zone in the process of the present invention have (a) a silica-magnesia support, and (b) at least two hydrogenating components, at least one of which must be a Group VI metal or compound thereof and at least one of which must be a Group VIII metal or compound thereof. It has been found that, where the catalyst comprises a Group VI metal or compound thereof alone, without a Group VIII metal or compound thereof, the catalyst has an unacceptably low activity. It has been found that, Where the catalyst comprises a Group VIII metal or compound thereof alone, without a Group VI metal or compound thereof, the catalyst has an exceptionally high fouling rate. However, where the catalyst comprises at least one Group VIII metal or compound thereof and also at least one Group VI metal or compound thereof, the catalyst has a high activity and a low fouling rate. The Group VI metals and compounds thereof that may be used include chromium, molybdenum and tungsten and compounds thereof. The Group VIII metals and compounds thereof that may be used include iron, cobalt, nickel, platinum, and palladium and compounds thereof. The most preferred catalysts comprise nickel and either tungsten or molybdenum on a silica-magnesia support, the catalyst in each case preferably being sulfided. The single main preferred catalyst which has been found to have the most outstanding qualities in the process of the present invention comprises nickel and tungsten on silica-magnesia, preferably sulfided. The Group VI metal or compounds thereof may be present in the catalyst in an amount from 1 to 40 weight percent, preferably from 2 to 25 weight percent, based on the total catalyst composite; the Group VIII metal or compound thereof may be present in an amount of from 1 to 20 weight percent, preferably from 2 to 12 weight percent, based on the total catalyst composite. The magnesia content of the silicamagnesia support may range from 5 to 75 weight percent, preferably from to 50 weight percent, and still more preferably from to 35 weight percent.

B. Preparation of catalyst-The silica-magnesia support of the catalyst can be prepared by any conventional method, and the plurality of hydrogenating components may be incorporated in the catalyst by any conventional method. A particularly effective method for preparing the catalyst is set forth in the following example.

Example I A powdery silica-magnesia material containing about 20% magnesia was compressed, together with about 5% by weight of a conventional glue-type bonding material used in catalyst preparation, into x pellets, and was calcined in air at 950 F. for six hours.

1000 cc. of the aforesaid calcined material were impregnated for four hours with 800 cc. of a solution of nickel nitrate containing 11.2% nickel, and the impregnated material was dried for 24 hours at 250 F. and then calcined for four hours at 900 F. The resulting product was a catalyst supportcontaining 9.43% nickeL' The aforesaid catalyst support was impregnated three 7 times with separate 800 ccJportions of a solution consisting of 960g. of tungstic acid (H WO dissolved in a mixture of.1152 cc. of ammonia (NH and 3460 cc. of

water. ments, the impregnated composite was dried at 250 F.

substantial amounts of sulfur compounds, the catalyst automatically will tend to become sulfided on the surface under the operating conditions of the process. It is somewhat rnore preferable to presulfide the catalyst before placing it on-stream, and such sulfiding may be accom plished by any conventional method.

D. Regeneration of the catalyst.lt is an outstanding advantage of the catalyst of the present invention that it may be regenerated, particularly in view of the difficulties that have been met. by the art in the regeneration of many prior art catalysts. While regeneration may be accomplished by any conventional method, and while the relative effectiveness of such methods may be readily determined by those skilled in the art, the regeneration method set forth in Table IV below is a highly effective one.

B. Preferred catalysts.-The preferred catalysts for use in the process of the present invention are set forth above.

F. Activity 0 catalyst for denitrificati0n.The catalyst of the present invention is a denitrification catalyst, as well as a hydrocracking catalyst, and in the process of the present invention performs both functions under the conditions of the process. The catalyst has excellent denitrification activity, but it is relatively insensitive to nitrogen,

, and is highly insensitive to nitrogen compared with a con- After each of the aforesaid impregnation treat- 7 for 20 hours, and calcined at 900 F. for four hours. The

C. Sulfiding the catalyst.Although the catalyst of the present invention maybe used in the unsulfided form, the sulfided form is preferable. With feeds containing any 'of the two groups.

ventional acidic hydrocracking catalyst such as nickel sul-' fide on silica-alumina.

Not only are a plurality of hydrogenation components, at least one of which must be a Group VI metal or compound thereof and at least one of which must be a Group VIII metal or compound thereof, essential to the hydrocracking activity of the catalyst of the present invention, but this same plurality of hydrogenation components is essential to the denitrification activity of the catalyst of the present invention. For example, the preferred nickeltungsten on silica-magnesia catalyst of the present invention would not have good denitrification activity if only nickel or only tungsten were present; single hydrogenating components, for example molybdenum or tungsten from Group VI or nickel or cobalt from Group VIII, are relatively ineffective for denitrification when not accompanied by a hydrogenating component from the other one- Further information regarding the denitrification activity of the catalyst is set forth in Table V below. a

G. Selectivity of catalyst for middle distillate producti0n.--The catalyst of the present invention has a high selectivity for the production of middle distillates from various hydrocarbon feeds. It has a much greater selectivity for the production of middle distillates than convenventional acidic hydrocracking catalysts, such as nickel sulfide on silica-alumina. The high yields of middle distillates resulting from the selectivity of the catalyst of the present invention for middle distillate product is unexpected in view of the selectivity for gasoline production that is characteristic of many prior art hydrocracking catalysts, for example nickel sulfide on silica-alumina. Further information regarding the selectivity of the present invention catalyst for the production of middle distillates is set forth in Table III below.

DESCRIPTION OF PROCESS FLOW ARRANGE- MENTS SUITABLE FOR. CARRYING OUT THE PROCESS OF THE PRESENT INVENTION Referring now to the drawing, there shown is a diagrammatic illustration of an embodiment of process units and flow pathssuitable for carrying out the process of the present invention.

[zone 5 from which hydrogen is recycled through line 6,

ammonia is withdrawn through line '7, and remaining materials are passed through line 8 to separation zone 9.

(1 From separation zone 9 a C and lighter stream, including isobutane, is withdrawn through line 10, and remaining materials are passed through line to separation zone 16. From separation zone 16 a light gasoline product is Withdrawn through line 17, a heavy gasoline product boiling from about 180 to 300 F. is withdrawn through line 18, and materials heavier than about 300 F. are passed through line 20 to separation zone 25.

From separation zone middle distillate products boiling from about 300 to 650 F. are withdrawn through line 26 and materials boiling above about 650 F. are recycled through line 27 to hydrocracking zone 2. If desired, a minor portion of the materials in line 27 may be withdrawn from the system through line 28. A portion of the materials in line 27 are passed through line 37 to hydrocracking zone 19, the exact amount depending upon the desired ratio between the products from hydrocracking zone 2 and the generally lighter products from zone 19. Hydrocracking zone 19 may contain a conventional acidic hydrocracking catalyst, for example nickel sulfide on silica-alumina, platinum on silica-alumina, etc., and may operate under conventional hydrocracking conditions, for example a pressure of from 500 to 3000 p.s.i.g. and a temperature of from 550 to 850 F. It is well known that such catalysts can be subjected to regeneration with an oxygen-containing gas under conventional regeneration conditions. Hydrocracking zone 19 is supplied with hydrogen through line 35. Zone 19 efiluent may be passed through line 36 to separation zone 16.

Hydrocracking zone 2 may comprise two hydrocracking reactors, each containing the catalyst of the present invention and each operating under the aforesaid process conditions. These two reactors may be arranged in a known manner so that alternately they can be connected in parallel and in series. When connected in parallel, they will operate to maximize middle distillate production, and when switched to series operation they may maximize gasoline or middle distillate production. In series operation, middle distillate production may be maximized by withdrawing middle distillate. as a product from the first reactor as well as from the second, for example from an interreactor fractionation zone. In series operation, gasoline production may be maximized by including the middle distillate produced in the first reactor in the feed to the second reactor. In either series arrangement, it is preferred to remove from the system any ammonia produced in the first reactor, rather than permitting it to pass to the second reactor. Such switch.- ing arrangements will enable the ratio of middle distillate to gasoline product to be varied in order to achieve further process application flexibility. In series operation to produce gasoline, where ammonia formed in the first reactor has been removed, the secondreactor, because it is operating with a feed that has been denitrified in the first reactor, is operable at lower temperatures, thus providing leeway for increase in severity of the operating conditions in the second reactor to increase gasoline production. The resulting gasoline, produced over the catalyst of the present invention, is isoparaffinic and of high quality, in contrast to the normal parafi'inic character of gasoline produced over hydrocracking catalysts having weak acidity.

Because the catalyst in zone 2 serves as an effective hydrofining catalyst, the materials in line 8 are low in nitrogen and therefore are especially suitable for further hydrocracking in the presence of the acidic catalyst in zone 19.

The process of the present invention is especially effective for converting heavy feed such as residua and propane deasphalted oils when a conventional denitrification zone is inserted between the first hydrocracking zone and the second hydrocracking zone of the process. Because such feeds generally are especially difiicult to denitrify, and because for most efiicient results the feed to the second conversion zone 19 here, containing an acidic hydrocracking catalyst, should have a minimum nitrogen level, the insertion of a conventional denitrification zone between the two hydrocracking zones in the present process can be of significant value.

The conventional denitrification zone may be inserted, for example, in line 8 or line 15, and may be operated under conventional denitrification conditions With either the silica-magnesia supported catalyst used in hydrocracking zone 2, or with any conventional denitrification catalyst. Such a three-stage process enables the heavier feeds to be hydrocracked and partially denitrified in the first stage, thereby reducing both the molecular weight and the nitrogen level of the feed and greatly accelerating the rate of the remaining denitrification to be accomplished in the second, or conventional, denitrification zone.

TABLE I.COMPARISON OF FIRST STAGE CATALYST OF PROCESS OF PRESENT INVENTION WITH CON- VENTIONAL CATALYSTS RE STARTING TEMPERA- TURES AND FOULING RATES The following table sets forth on a comparative basis single stage hydrocracking results of processing a 650 to 980 F. heavy Arabian gas oil having a total nitrogen content of 660 to 700 ppm. at the indicated average catalyst temperature, about to volume percent substantially constant per-pass conversion to products boiling below the initial boiling point of the feed, 1.0 LHSV, 2000 p.s.i.g. and a hydrogen rate sufilcient to permit withdrawal from the hydrocracking zone of 4500 s.c.f. of hydrogen per barrel of feed, over the first stage catalyst of the present invention compared with hydrocracking the same feed under the same conditions over various prior art catalysts. The factors compared are: 1) the average catalyst temperature necessary to give said substantially constant 50 to 55% per-pass conversion, which substantially constant conversion is indicated by the substantially constant product gravity shown; and (2) the catalyst fouling rate.

Support Hydrogenating com- Av. eat. Cat. ponent (percent) Area, tomp., F. Product Fouling N 0. mJ/g. necessary gravity rate for desired SlOz-AlgOa, SiOz-MgO Ni W Mo Pt conversion 1 27% MgO 759 40. 0 None observable. 2 27% MgO" 755 40. 3 D0. 3. 27% Mg0 756 39. 9 Moderate. 4- 27% Mg0 767 39. 5 Do. 5--- 27% MgO 790 39. 5 High. 6 27% Mg0 765 40. 3 Very high. 7 27% MgO 845 38. 5 Do. 8... 25% A1203. 790 40. 3 None observable. 9.-. 28% A1203. 792 40.0 Moderate. 10. 47% A1203. 780 40. 0 D0. ll 47% A1203- 790 39. 8 D0. 12 10% A1203- 805 39. 8 High.

B 0.05 F. per hour.

b -0.100.15 F. per hour.

6 -0.5 F. per hour. 4 -1.0 F. per hour.

lysts 1 to 4 resulted in both (1) the desired conversion rate ata reasonably low average catalyst temperature, in each case 767 F. or below, and (2) a reasonably low catalyst fouling rate, in each case, moderate, as defined, or less. It will be noted that catalysts 5 to 7, each having one hydrogenating component only, on a silicamagnesia support, resulted in an excessive catalyst fouling rate, i.e., one that was high, as defined, or higher. It will be noted that catalysts 8 to 12, each having a silica alumina support rather than the silica-magnesia support of the first stage catalyst of the present invention, resulted in the desired conversion being obtained only at an unreasonably high average catalyst temperature, in each case 780 F. or above.

TABLE II.'COMPARISON OF FIRST STAGE CATALYST OF PRESENT INVENTION WITH CONVENTIONAL CATALYSTS RE ACIDITY, STARTING TEMPERATURE, ISO TO NORMAL Ci PRODUCT RATIO, MIDDLE DIs- TILLATE T GASOLINE PRODUCT RATIO AND NOR- lgoAfisPARAFFlN CONTENT OF UNCONVERTED BOT- The following table sets forth on a comparative basis single-stage hydrocracking results of processing an Arabian straight run feed, at 0.5 LHSV, 2000 p.s.i.a, 60% per-pass conversion to products boiling below the initial boiling point of the feed, and extinction recycle, over the first stage catalyst of the present invention, compared with hydrocracking the same feed under the same conditions over various prior art catalysts. The factors compared are: (1) starting temperature necessary to give said 60% per-pass conversion; (2) the ratio of iC to nCi, in the product; (3) the ratio of 400 to 650 F. product to C to 400 F. product; i.e., the ratio of middle distillate production to gasoline production; (4) the hydrogen consumption, in s.c.f. per barrel of feed; and (5) the change, in F., of the pour point of the same bottoms fraction in each case, from the pour point of the feed, as an indication of the effect of the reaction in each case on normal parafiins in the system.

dicated to have a greater normal parafiin content than the feed. With Catalysts B, C and D the unconverted bottoms material is less paraffinic than the feed, which is extremely desirable because normal paraifins are refractory to hydrocracking and therefore build up in recycle bottoms during recycle operation. A build-up of refractory normal paraffins can effectively prevent the practical use of recycle hydrocracking to produce middle distillates, because prohibitive temperature and pressure increases can be required to crack these refractory compounds; (5) with Catalysts B, C and D the undesirable refractory normal paraffins are selectively cracked and/or are isomerized to valuable isoparaflins, to an extent adequate to permit satisfactory recycle operation.

TABLE III.-COMPARISON OF FIRST STAGE CATALYST OF PRESENT INVENTION WITH CATALYST HAVING SILICA-ALUMINA SUPPORT RE PRODUCTION OF MIDDLE DISTILLATES Total couver- Percent of Catalyst Temp, sion to prodproduct in F. ucts boiling 400650 F.

below 650 F. boiling range NlW on SiOs-AlzOa 650 53. 2 41 NiW on SiO -MgO 650 53. 4 49 r TABLE IV.-REGENERAB1LITY on FIRST STAGE CAT:

ALYST OF PRESENT INVENTION AND REGENERATED CATALYST ACTIVITY I Start. 400650 F./ H2, Bottoms Cat. Cat. comp. 'I., F iC /IIC 05-400" F. s.o.f./bbl. pour point change, F.

A 6% Ni+22% Mo on A1 03.-." 850 0. 2 1. 4 1,300 +13 B NiMo on Sim-A1 0 30% Sio 705 0.6 1. 4 1, 700 3s 0..... NiW on SiOz-MgO, 27% MgO- 720 1.1 1. 4 2, 000 -25 D- NiMo on Sim-A1 03, 90% SiO2 790 0.6 0.9 1,800 15 6% Ni on Slog-A1203, 90% S102 740 1.1 0. 4 2,600 +19 The catalysts in the above table are set forth in order of the present invention. A catalyst comprising 7.0%

of increasing acidities, with Catalyst A having the lowest acidity increases, the product iso to normal ratio inlyst C is an example of the first stage catalyst of the present invention, while the other catalysts indicated are representative of various prior art catalysts.- 7

From the above table it will be noted that: (1) as acidity increases, the prdouct iso to normal ratio increases smoothly, except in the case of the first stage catalyst of the present invention, with which is obtained a higher ratio than would be expected'from inspection of the prior art catalysts alone; (2) as acidity increases, the product middle distillate to gasoline ratio decreases, but remains as high with the first stage catalyst of the present invention as with catalysts of weaker acidity, which is entirely unexpected; heretofore, it has been believed that a catalyst of higher acidity would produce less middle distillate per unit of gasoline production than a'more weakly acidic catalyst; (3) as acidity increases, hydrogen consumption increases smoothly, except in the case of the first stage catalyst of the present invention, with which is obtained a higher hydrogen consumption and improved product quality; (4) as acidity increases, the normal parafiin content of the uncoverted bottoms material, as indicated by the F. change in bottoms pour point from the pour point of the feed, decreases and then increases; with Catalysts A and E the bottoms material is innickel and 19.3% tungsten on a silica-magnesia support containing 27.7% magnesia, with van area of 316 mF/gz, was placed in hydrocracking reactor and contacted for 120 hours at 2000 p.s.i.g., 1.0 LHSV,759 F. average catalyst temperature, and hydrogen rate of 5500 s.c.f.

per barrel of feed, with a hydrocarbon feed boiling from 650 to 982 F., said feed having agravity of 235 API, an aniline point of 178.9% F., a pour point of ASTM and a total nitrogen content of 665 p.p.m. The catalyst under these conditions converted54 weight percent of the feed to products boiling below the 650 F. initial boiling point of the feed, and the gravity of the total products produced was 40.3 API.

After the foregoing on-stream period the catalyst was regenerated in a nitrogen-oxygen stream, at a reactor pressure of 600 p.s.i.g. and a gas rate of 20 cubic feet per hour, for a total period of 20 hours. During this period the temperature was slowly raised from 500 to 900 F., and the oxygen content of the gas was raised from 0.1 to 4.0 volume percent.

The regenerated catalyst, having an area of 237 m. /g., was then used to hydrocrack the same feed that it had been used to hydrocrack prior to regeneration, under the same conditions. The activity of the regenerated catalyst was substantially equal to its original fresh activity, as indicated by its conversion, at an average catalyst tem- 1 1 perature of 750 F., of 48 weight percent of the feed to products boiling below the initial boiling point of the feed, the total products produced having a gravity of 38.8 API.

The following summarizes the foregoing results:

TABLE V.--COHPARISON OF FIRST STAGE CATALYST OF PRESENT INVENTION WITH CONVENTIONAL CATALYSTS RE DENITRIFICATION ABILITY, NITRO- GEN SENSITIVITY AND ABILITY TO CONVERT NITRO- GEN-CONTAINING FEEDS TO MIDDLE DISTILLATES The following table indicates results obtainable with the first stage catalyst of the present invention and with a low acidity prior art catalyst, and a high acidity prior art catalyst, respectively, when used to hydrocrack a 650 to 1000 F. hydrocarbon feed at the indicated temperatures, and at 1.0 LHSV, 2000 p.s.i.g. and a hydrogen rate of 6500 s.c.f. per barrel, with extinction recycle of unconverted products. The indicated low nitrogen feeds refer to feeds containing from zero to p.p.m. nitrogen and the indicated high nitrogen feeds refer to feeds containing above 10 p.p.m. nitrogen, for example 10 to 1000 ppm. nitrogen.

NiW on S102- 6% Ni+22% 6% Ni on MgO, 27% B10 011 A1203 Slot-A1203, MgO 90% Bio:

Temperature, in F. for

50% conversion with low feeds 650 850 550 Temperature, in F. for

50% conversion with high N feeds 740 850 760 Maximum yield of 320650 F. middle distillate, with high N feeds, percent 75-85 75-85 55-65 iCilnCi product ratio High Low High Pour point of synthetic middle distillate product,

F -40 -00 Relative denitrification aetivit 1.8 1. 0 0. 1 Sensitivity to S"--- Nil Nil Nil Sensitivity to N Low Nil High From the foregoing it will be seen that the process of the present invention is effective to convert a wide range of hydrocarbon feeds to valuable products, mainly middle distillates, heavy gasoline and light gasoline.

Although only specific embodiments of the present invention have been described, numerous variations could be made in those embodiments without departing from the spirit of the invention, and all such variations that fall within the scope of the appended claims are intended to be embraced thereby.

We claim:

1. In a process for producing gasoline and middle distillates from a hydrocarbon feed selected from the group consisting of petroleum distillates boiling from 650 to i2 1100 F. and petroleum residua boiling above 650 F., which comprises contacting said feed and from 1000 to 10,000 s.c.f. of hydrogen per barrel of said feed in a first catalytic conversion zone at a temperature from 500 to 950 F., a pressure from 1000 to 2500 p.s.i.g. and an LHSV of 0.1 to 4.0, and producing materials boiling above 650 F. in a second catalytic conversion zone in the presence of an acidic catalyst from a 650 F.+ portion of the efiluent from said first conversion zone, the improvement which comprises using in said first conversion zone a catalyst comprising at least one hydrogenating component selected from the Group VI metals and compounds of Group VI metals and at least one hydrogenating component selected from the Group VIII metals and compounds of Group VIII metals and a catalyst support comprising silica-magnesia, recovering from the effluent from said first conversion zone a fraction boiling above about 650 F., a middle distillate product, a heavy gasoline product and a light gasoline product, withdrawing said products from the system, hydrocracking in a second conversion zone in the presence of an active acidic hydrocracking catalyst at least a portion of said fraction from said first conversion zone boiling above about 650 F., recovering from said second conversion zone a fraction boiling above about 650 F., a middle distillate product, a heavy gasoline product and a light gasoline product, and returning to said first conversion zone at least a portion of said fraction from said second conversion zone boiling above about 650 F., whereby a wide range of products including light and heavy gasolines and middle distillates are produced in and recovered from each of said two conversion zones.

2. A process as in claim 1, wherein said hydrogenating component selected from the Group VI metals and compounds of Group VI metals is present in an amount from 1 to 40 weight percent, based on the total catalyst composite.

3. A process as in claim 1, wherein said hydrogenating component selected from the Group VIII metals and compounds of Group VIII metals is present in an amount from 1 to 20 weight percent, based on the total catalyst composite.

4. A process as in claim 1 wherein said hydrogenating components comprise nickel and tungsten.

5. A process as in claim 1 wherein at least two reactors are used in said first conversion zone, each containing said silica-magnesia supported catalyst, and wherein said reactors are so arranged that they can be switched from parallel, for maximizing middle distillate production, to series, for maximizing gasoline production, whereby the ratio of middle distillate product to gasoline product can be varied.

Eeferences Cited by the Examiner UNITED STATES PATENTS 2,952,611 9/60 Haxton et a1. 208 3,047,690 7/62. Myers 20859 3,072,560 1/63 Paterson et al 208111 3,119,765 1/64 Corneil et al. 20859 ALPHONSO D. SULLIVAN, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,180,817 April 27, 1965 William H. Claussen et al. A

It is hereby certified that error appears in the above numbered patent reqiiring correction and that the said Letters Patent should read as correctedbelow.

Column 1, line 16, for "residual" read residua column 5, line 4, for "GROUP" read ZONE line 53, for "20%" read 28% column 9, lines 50 to 52, strike out "with Catalyst A having the lowest acidity increases, the product iso to normal ratio in-lyst C is an example" and insert instead with Catalyst A having the lowest acidity and Catalyst E having the highest acidity. Catalyst C is an example Signed and sealed this 28th day of September 1965.

(SEAL) Altest:

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

Claims

1. IN A PROCESS FOR PRODUCING GASOLINE AND MIDDLE DISTILLATES FROM A HYDROCARBON FEED SELECTED FROM THE GROUP CONSISTING OF PETROLEUM DISTILLATES BOILING FROM 650* TO 1100*F. AND PETROLEUM RESIDUA BOILING ABOVE 650*F., WHICH COMPRISES CONTACTING SAID FEED AND FROM 1000 TO 10,000 S.C.F. OF HYDROGEN PER BARREL OF SAID FEED IN A FIRST CATALYTIC CONVERSION ZONE AT A TEMPERATURE FROM 500* TO 950*F., A PRESSURE FROM 1000 TO 2500 P.S.I.G. AND AN LHSV OF 0.1 TO 4.0, AND PRODUCING MATERIALS BOILING ABOVE 650*F. IN A SECOND CATALYTIC CONVERSION ZONE IN THE PRESENCE OF AN ACIDIC CATALYST FROM A 650*F.+ PORTION OF THE EFFLUENT FROM SAID FIRST CONVERSION ZONE, THE IMPROVEMENT WHICH COMPRISES USING IN SAID FIRST CONVERSION ZONE A CATALYST COMPRISING AT LEAST ONE HYDROGENATING COMPONENT SELECTED FROM THE GROUP VI METALS AND COMPOUNDS OF GROUP VI METALS AND AT LEAST ONE HYDROGENATING COMPONENT SELECTED FROM THE GROUP VIII METALS AND COMPOUNDS OF GROUP VIII METALS AND A CATALYST SUPPORT COMPRISING SILICA-MAGNESIA, RECOVERING FROM THE EFFLUENT FROM SAID FIRST CONVERSION ZONE A FRACTION BOILING ABOVE ABOUT 650*F., A MIDDLE DISTILLATE PRODUCT, A HEAVY GASOLINE PRODUCT AND A LIGHT GASOLINE PRODUCT, WITHDRAWING SAID PRODUCTS FROM THE SYSTEM, HYDROCRACKING IN A SECOND CONVERSION ZONE IN THE PRESENCE OF AN ACTIVE ACIDIC HYDROCRACKING CATALYST AT LEAST A PORTION OF SAID FRACTION FROM SAID FIRST CONVERSION ZONE BOILING ABOVE ABOUT 650*F., RECOVERING FROM SAID SECOND CONVERSION ZONE A FRACTION BOILING ABOVE ABOUT 650*F., A MIDDLE DISTILLATE PRODUCT, A HEAVY GASOLINE PRODUCT AND A LIGHT GASOLINE PRODUCT, AND RETURNING TO SAID FIRST CONVERSION ZONE AT LEAST A PORTION OF SAID FRACTION FROM SAID SECOND CONVERSION ZONE BOILING ABOVE ABOUT 650*F., WHEREBY A WIDE RANGE OF PRODUCTS INCLUDING LIGHT AND HEAVY GASOLINES AND MIDDLE DISTILLATES ARE PRODUCED IN AND RECOVERED FROM EACH OF SAID TWO CONVERSION ZONES.