US3268437A - Hydrocracking of nitrogen containing hydrocarbon oils for the preparation of middle oils - Google Patents

Description

Aug. 23, 1966 BEUTHER ET AL 3,268,437

HYDROCRACKING OF NITROGEN CONTAINING HYDROCARBON OILS FOR THE PREPARATION OF MIDDLE OILS Filed Aug. 29. 1965 ATTOPNEY United States Patent HYDROCRACKING OF NlTRGGEN CGNTAINING HYDRGCARBON 0E5 FOR THE PREPARATEON 0F MIDDLE OILS Harold Beuther, Gihsonia, and Bruce K. fichmid, Pittsburgh, Pa., assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Filed Aug. 29, 1963, Ser. No. 305,543 Claims. (Cl. 20861) This invention relates to improved hydrocracking procedure and in particular to an inexpensive process for producing middle oils, especially furnace oil, from higher boiling petroleum fractions.

It is well known that petroleum fractions can be hydro cracked into lower boiling materials. Formation of gasoline is usually the primary objective. However, it is also known that middle oils such as furnace oil, jet and diesel fuels can be produced by this procedure. Hydrocracking procedures directed primarily toward the production of middle oils necessarily involve the hydrocracking of relatively high boiling feed stocks. The conversion of these materials is relatively diflicult as compared with the conversion of middle oils into gasoline. Furthermore it is difficult to restrain or control the hydrocracking reaction in order to form relatively high ratios of middle oils and prevent the reaction from proceeding to gasoline formation. Another disadvantage of prior procedures for preparing middle oils by hydrocracking is that they have involved the use of relatively high pressures. These high pressures are unattractive because they result in high hydrogen consumption and involve high cost equipment.

This invention has for its object to provide improved procedure for hydrocracking of high boiling feed stocks into middle oils in relatively high ratios as compared with gasoline. Another object is to provide a relatively economical process for hydrocracking higher boiling stocks into middle oils. A still further object is to provide improved procedure in which a heavy stock is hydrocracked into a middle oil which has unusual properties which qualify it for use in viscosity reduction of heavy fuel oils. Another object is to improve the state of the art. Other objects will appear hereinafter.

These and other objects are accomplished in accordance with our invention by subjecting a feed stock which has a higher boiling point than the desired middle oil to hydrocracking in the presence of a two-component catalyst, one component of which comprises nickel-tungsten sulfide and the other component of which comprises a siliceous cracking base having a cracking activity of at least 45 Al. This treatment is carried out at between about 400 and 1200 psi. hydrogen partial pressure, at a temperature between about 800 and 900 F., at a space velocity between about 2 and 8 and maintaining conversion at between about 20 and 50 percent. The feed stock must contain at least about 100 ppm. of nitrogen as nitrogenous compounds. Amounts above about 600 ppm. are advantageous and may be as high as 0.3 percent nitrogen as nitrogenous compounds. We have found in accordance with our invention that by operating in this manner a high ratio of middle oil to gasoline is obtained. We have also found that a relatively long catalyst life can be obtained even at these moderate pressures. This permits a throughput of about 1200 to 12,000 between regenerations of the catalyst. Therefore, by operating in this manner we have provided an economical moderate pressure method of converting high boiling stocks into middle oils and at the same time obtained the advantages of relatively high throughputs or long onstream periods between regenerations.

The predominant part of the feed stock should boil above about 675 F. It may contain minor amounts of Patented August 23, 1966 "ice materials having a lower boiling point, but predominant amounts are not desirable since these lower boiling materials are the products which are to be produced. The feed stock may be a straight run atmospheric or vacuum distillate of petroleum. It may be a wide boiling range fraction boiling above about 675 P. such as would be ordinarily produced by atmospheric or vacuum distillation of petroleum. On the other hand it may be a narrow boiling fraction of petroleum which boils above about 675 F. Cracked gas oils or gas oils from coking or visbreaking can also be used for this process. Use of these stocks would have the advantage that they are lower value materials and would be more economical and appropriate for producing cutter oils for low-value residual fuels. The feed must contain at least p.p.m. of nitrogenous materials. If this nitrogen is not present, the highly active catalyst which is employed will result in extensive hydrocracking to form undesirably large amounts of gasoline. Also deposition of coke on the catalyst will take place at an excessive rate, necessitating uneconomically frequent regenerations. Furthermore absence of this amount of nitrogenous materials would increase hydrogen consumption, and it is an advantage of our invention that hydrogen consumption is reduced. These nitrogenous materials are usually present in these petroleum fractions in the required amounts. However, if the feed stock in question is low in nitrogen, it may be mixed with a petroleum fraction high in nitrogenous impurities or nitrogen compounds such as amines may be added. The feed should be substantially free of asphaltic materials.

The catalyst which is employed in our progress must be a highly active catalyst. A nickel-tungsten sulfide catalyst is the only catalyst which We have found which has satisfactory activity and life under the conditions we employ. The catalyst may contain between about 5 and 40 percent and preferably 10 to 25 percent of nickel plus tungsten (determined as metals). The atomic ratio may be between 1 atom of tungsten to 0.1 of nickel to 1 atom of tungsten to 5 atoms of nickel. The catalyst may be pro-sulfided or it may be sulfided in situ, i.e., by the presence of sulfur in the hydrogen and/ or feed streams. We prefer to employ a pre-sulfided catalyst. The catalyst must be maintained in sulfided condition duringuse. This necessitates the presence of or the addition of sulfur or sulfur compounds during the onstream reaction. Sulfur in an amount above about 0.1 percent of the feed is desirable. Amounts of about 0.1 to 2 percent are advantageous. This sulfur content includes the sulfur in the recycle hydrogen, the recycle feed and the fresh feed.

If the feed does not contain suflicient sulfur any organic or inorganic sulfur compound having a hydrogen-to-sulfur or a carbon-to-sulfur linkage as Well as elemental sulfur can be used such as butyl mercaptan, thiophene, hydrogen sulfide, etc. While we have referred to the catalyst as being sulfided, this does not necessarily mean that the metals are necessarily sulfides. It does mean that the catalyst contains sulfur.

These supports may also contain additional components However, the metals may be present in form of other sulfur compounds than sulfides,

commonly present in such cracking catalysts such as berillia, 'zirconia, thoria, etc. The nickel and tungsten components may be composited with the siliceous cracking support in any desired manner. Thus the nickel and tungsten may be co-precipitated thereon or the two components may be deposited in sequence. Furthermore it is satisfactory to prepare the siliceous cracking base in the presence of nickel and tungsten so that the entire catalyst including the carrier is simultaneously formed.

It is advantageous, although not necessary, to use a catalyst which contains between about 0.1 and 5 percent halogen such as fluorine or chlorine. This increases the initial activity of the catalyst as well as extending its life at the moderate pressures and high temperatures employed in our process. The halogen is advantageously incorporated in the siliceous cracking base during its preparation. However, it may be incorporated in the catalyst during use by adding the halogen to the feed stock and/ or hydrogen.

Our invention is carried out at a hydrogen partial pressure between about 400 and L200 p.s.i. While higher partial pressures can be used, we do not include them within the scope of our invention for several reasons. Thus it is an objective of our invention to provide a moderate pressure procedure for this particular type of hy-drocracking operation. Also higher pressures are not only relatively costly but result in a lower ratio of middle oil to gasoline which is contrary to the objectives of our invention. Also these higher pressures increase hydrogen consumption, which is contrary to one of the objectives of our invention. It is necessary to employ a temperature between about 800 and 900 F. during the onstream reaction and to keep conversion at a relatively low rate of 20 to 50 percent in order to obtain economically attractive throughputs. Conversion is maintained in this range by selecting a temperature and space velocity which will result in the desired conversion. Usually a space velocity of between about 2 and 8 volumes of feed stock per volume of catalyst per hour will be found satisfactory at the 800 to 900 F. temperature. By conversion we mean net make of gasoline plus furnace oil having a boiling point from 100 to 675 F.

Although the process of our invention is carried out at a temperature between about 800 and 900 F., it is advantageous during initial start-up operations using a new catalyst or a freshly regenerated catalyst to employ a temperature between about 600 and 800 F. to take the high activity edge off the catalyst prior to use in the process of our invention at the more elevated temperatures. Thus these fresh catalysts have exceedingly high activity and While high activity is essential in our invention, this excessive activity would cause rapid initial coking if the catalyst were initially employed at the relatively high temperatures of our invention. Therefore the catalyst is contacted with the feed stock at this lower temperature until this high activity edge has been taken off the catalyst. This will ordinarily be accomplished after about 8 to 24 hours. The temperature is then increased to a temperature within the range of 800 to 900 R, which temperature gives the desired conversion of 20 to 50 percent at the selected space velocity between 2 and 8.

We may employ 5000 or more standard cubic feet of hydrogen per barrel of feed. It is advantageous to employ between about 8000 and 12,000 standard cubic feet of hydrogen per barrel of feed. However, higher amounts of hydrogen such as up to 20,000 standard cubic feet or more per barrel of feed can be employed. It is undesirable to employ less than about 5000 s.c.f. of hydrogen per barrel of feed since these lower hydrogen rates result in increased deposition of coke, which deactivates the catalyst and necessitates shorter throughputs. Fur-thermore the use of higher hydrogen ratios such as 5000 s.c.f. per barrel and above increases the ratio of middle oil to gasoline which is one of the primary objectives of our invention.

As the above treatment is continued the activity of the catalyst will gradually decrease. When this activity reaches an undesirably low value, i.e., a conversion below about 20 percent, the reaction is terminated and the catalyst'is regenerated by combustion in the usual manner.

The regenerated catalyst is then re-used in the process preferably after sulfiding and incorporation of halogen lost during the reaction and/ or regeneration. It is advantageous to gradually increase the temperature as the catalyst becomes deactivated in order to maintain conversion approximately constant. When a point is reached where an excessive rate of temperature increase is necessary to maintain desired conversion or when the maximum temperature of 900 F. is reached, the reaction is terminated. The catalyst is regenerated in the usual manner and then re-used.

The use of conversions in the range of .20 to 50 percent is an important factor in accomplishing the objectives of our invention. Thus if a conversion above about 50 percent is employed it will be found that the throughput will be markedly reduced, i.e., the activity of the catalyst will be rapidly reduced due to deposition of coke at these excessive conversions. While conversions below about 20 are satisfactory insofar as throughput is concerned, they are not economically attractive. A conversion of between about 30 and 40 percent is especially advantageous.

The effluent from the hydrocracking reactor is separated in known manner. Thus the hydrogen may be separated in .a high pressure separator and the separated hydrogen may be recycled for re-use in the process. Since hydrocarbon gases, ammonia, hydrogen sulfide, etc. are formed during hydrocracking, at least some of the hydrogen should be bled from the system and make-up hydrogen of a higher concentration added. The liquid products from hydrocracking are subjected to distillation to separate gasoline, middle oil, etc. and the unconverted material, i.e., that boiling above about 675 F. may be recycled to the hydrocracking step if desired. It is substantially upgraded and may be used in other applicaiions where a low nitrogen and low sulfur feed is required. Thus it constitutes an excellent feed stock for catalytic cracking as will be evident from the data in Table III of the following example. The middle oil, i.e., that having a boiling range in the range between about 300 and 675 F., constitutes a good quality furnace oil which may be used as such or which may be blended with a straight run furnace oil to obtain a high quality product. middle oil fraction is advantageously employed for reducing the viscosity of residual petroleum fractions such as atmospheric and vacuum reduced crude. These low-grade residual stocks have such a high viscosity that it is necessary to dilute them with higher quality and more valuable lighter hydrocarbons to improve their free-flowing properties. The middle oil produced in our invention is particularly advantageous for this purpose. Thus, the middle oil produced in accordance with.

our invention has a higher heat of combustion than a middle oil produced by conventional hydrocracking. In addition, the preferred middle distillate is produced at a much lower cost, resulting from the use of a lower operating pressure, a higher space velocity, and a lower hydrogen consumption. The relatively low cost of this oil makes it especially advantageous for use as cutter oil for residual fuels. This low cost oil can be used to replace high value straight run kerosene, which is often currently used as cutter oil to decrease viscosity and pour points of residual fuels.

In order to illustrate our invention in greater detail, reference is made to the attached drawing showing a simplified flow diagram of a preferred employment of our invention.

In the process of the drawing a feed stock boiling above 675 F. and containing at least ppm. of nitrogenous compounds is fed by means of line 10 into bydrocracking reactor 12. Hydrogen is charged to reactor :12 by means of line 14 at a rate of at least 5,000 standard cubic feet of hydrogen per barrel of feed introduced through line '10. The hydrogen of line 14 is contacted with the feed of line in hydrocracking reactor 12 at a hydrogen partial pressure in the range from 400 to 1200 p.s.i. and at a temperature between 800 and 900 F. in the presence of a sulfided nickel-tungsten-halogen catalyst composited with a siliceous cracking base, which base has a cracking activity index above about 45. This is the catalyst required by our invention and described previously. The particular conditions employed in reactor 12 are selected so as to maintain a conversion, i.e., a net make of products boiling in the range of 100 to 675 F., between about and 50 percent. The effluent is removed from reactor 12 by means of line 16 and passed to distillation column 18. In distillation column 18 the hydrocracked product boiling below 675 F. is removed overhead by means of line 20, while that portion of the effluent boiling above 675 F. is removed from the bottom of distillation column 18 by means of line 22 and passed to catalytic cracker 24. The operating conditions and catalyst employed in cracker 24 can be selected from those catalysts and conditions wellknown to the art. The catalytically cracked efiiuent is removed from cracker 24 by means of line 26.

EXAMPLE A Kuwait heavy vacuum gas oil, having the properties listed in Table I, was hydrocracked at the conditions of this invention (run No. 1), and also at conventional conditions for hydrocracking of heavy gas oils (run No. 2). The operating conditions and results of these runs are given in Table II, with the exception of the gas rate which was 10,000 s.c.f. of hydrogen per barrel of feed. Both of these runs were made using the same nickeltnngsten sulfide silica-alumina catalyst, promoted with fluorine (6% Nil9% W2% F on 25% Al O 75% SiO The activity index of the silica-alumina support was 76.

The data of Table II show that the hydrocracking of heavy gas oil in accordance with our invention has sev eral advantages. First, the ratio of middle distillate to gasoline is higher, a distinct advantage in areas where the demand for naphtha and gasoline is low and the demand for fuel oils relatively high. Second, the heat of combustion of the oil produced at these conditions is higher than that of the furnace oil produced at conventional conditions.

The third major advantage of our invention is the lower cost of operation. This results from :the use of a lower operating pressure and a high liquid hourly space velocity, as well as a low hydrogen consumption. This is especially advantageous where the objective of the process is to produce a middle distillate suitable for use as cutter oil in low-value residual fuels.

The major problem in low pressure hydrocracking of furnace oil is catalyst deactivation, but thisis minimized by maintaining the conversion level below about 50 percent. At these lower conversion levels, catalyst life between regenerations i-s sufiiciently long (estimated 13 months depending upon actual conditions) to make this type of processing a practical operation. The low rate of catalyst deactivation was illustrated by a long throughput experiment made at the conditions of run No. 1. In this experiment, the conversion decreased very slightly, from about percent to about 28 percent in 300 hours. In actual commercial operation of the process, the conversion would be maintained constant by slightly increasing the temperature as the run progresses.

In a similar experiment with :the same feed and catalyst but at 1000 p.s.i.g., 800 F, and 1.0 LHSV, the conversion was initially 72 percent. At this high level of conversion, however, catalyst deactivation was rapid, the conversion decreasing to 65 percent in 12 hours. This experiment shows the advantages of maintaining the conversion at a moderate level, preferably below about 50 percent.

In Table III we have given data comparing the feed with that portion of the product from run No. 2 of Table II which boiled above 675 F. These data show that this fraction is a high quality feed stock for catalytic cracking.

Table l Gravity, API 20.7 Sulfur, percent by weight 3.2 Nitrogen, p.p.m. 970 ASTM vacuum distillation:

Over point, F. 459 5% 698 10% 722 30% 799 50% 862 70% 919 Table II Run No. 1 Run No 2 Conditions 1,000 p.s.i.g., 2,000 p.s.i.g., 800 F., 4.0 750 F.. 0.5 LHSV LHSV Conversion, Minus Vol. Percent,

675 F 30. 0 73. 3 Hydrogen Consumption, s.c.f./bbl, 700 1300 Furnace Oil/Gasoline Ratio, 400-675 5400 F r 3.5 1.0 Heat of Combustion of Furnace Oil,

Btu/gal 140, 000 137, 500

Table III 67 5 F. Inspections Charge Product Fraction Gravity, API 20.7 27. 3 Sulfur, Percent 3. 2 0.15 Nitrogen, p.p.m. 970 530 aracterization Fact 11.71 12.12

We claim:

1. The hydrocracking process for preparing a middle oil without substantially deactivating the catalyst which comprises subjecting a feed stock having less than 5 percent by volume of components boiling below about 675 F., containing at least about 100 p.p.m. of nitrogenous compounds to treatment with hydrogen in an amount of at least 5000 s.c.f. of hydrogen per barrel of feed stock at a hydrogen partial pressure between about 400 and 1200 p.s.i., at a temperature between about 800 and 900 F. and at a liquid hourly space velocity from about 2.0 to about 8.0 in the presence of a sulfided nickel-tungsten catalyst composited with a siliceous cracking base, which base ha a cracking activity index above about 45, maintaining conversion (net make of gasoline plus middle oil B.P. 100-675 F.) between about 20 and 50 percent with a ratio of middle oil (400675 F.) to gasoline (C 400 F.) in the converted product of at least 2:1 and continuing said treatment for a throughput of at least 1200 volumes of feed per volume of catalyst.

2. The hydrocra-cking process for preparing a middle oil without substantially deactivating the catalyst which comprises subjecting a feed stock having less than 5 percent by volume of components boiling below about 675 F., containing at least about 100 p.p.m. of nitrogenous compounds to treatment with hydrogen in an amount of at least 5000 s.c.f. of hydrogen per barrel of feed stock at a hydrogen partial pressure between about 400 and 1200 p.s.i., at a temperature between about 800 and 900 F. and at a liquid hourly space velocity from about 2.0 to about 8.0 in the presence of a sulfided 'nickel-tungsten-halogen catalyst composited with a sili- .ceous cracking base, which base has a cracking activity index above about 45, maintaining conversion (net make of gasoline plus middle oil B.P. 100-675 F.) between about 20 and 50 percent with a ratio of middle oil (400 675 F.) to gasoline (C 400 F.) in the converted product of at least 2:1, continuing said treatment for a throughput of at least 1200 volumes of feed per volume of catalyst, subjecting the product to distillation to separate a fraction boiling below about 675 F. and above about 675 F. and subjecting this last mentioned fraction to catalytic cracking.

3. The hydrocracking process for preparing a middle oil without substantially deactivating the catalyst which comprises subjecting a heavy gas oil having less than 5 percent by volume of components boiling below about 675 F., containing at least about 100 ppm. of nitrogenous compounds .to treatment with hydrogen in an amount of at least 5000 s.c.-f. of hydrogen per barrel of feed stock at a hydrogen partial pressure between about 400 and 1200 p.s.i. at a temperature between about 800 and 900 F. and at a liquid hourly space velocity from about 2.0 to about 8.0 in the presence of a sulfided nickel-tungsten-halogen catalyst composited with a siliceous cracking base, which base has a cracking activity index above about 45, maintaining conversion (net make of gasoline plus middle oil B.P. 100- 675 F.) between about 20 and 50 percent with a ratio of middle oil (400-675 F.) to gasoline (C 400 F.) in the converted product of at least 2:1 and continuing said treatment for a throughput of at least 1200 volumes of feed per volume of catalyst.

4. The hydrocracking process for preparing middle oils without substantially deactivating the catalyst which comprises subjecting a straight run heavy gas oil having less than 5 percent by volume of components boiling below about 675 F., containing at least about 100 ppm. of nitrogenous compounds to treatment with hydrogen in an amount of at least 5000 s.c.f. of hydrogen per barrel of feed stock at a hydrogen partial pressure between about 400 and 1200 p.s.i. at a temperature between about 600 and 800 F. and at a liquid hourly space velocity from about 2.0 to about 8.0 in the presence of a sulfided nickel-tungsten-halogen catalyst composited with a siliceous cracking base, which base has a cracking activity index above about 45, for a period of time between about 8 and 24 hours, thereafter increasing the temperature to between about 800 and 900 F. and maintaining conversion (net make of gasoline plus middle oil B.P. 100-675 F.) between about 20 and 50 percent with a ratio of middle oil ,(400675 F.) to gasoline (C -400 F.) in the converted product of at least 2:1 for a throughput of at least 1200 volumes of feed per volume of catalyst.

' .5. The hydrocracking process for preparing middle 'oils without substantially deactivating the catalyst which comprises subjecting a straight run heavy gas oil having less than 5 percent by volume of components boiling below about 67 5 F., containing at least about 100 ppm. of nitrogenous compounds to treatment with hydrogen in anamount of at least 5000 s.c.f. of hydrogen per barrel of feed stock at a hydrogen partial pressure between about 400 and 1200 p.s.i., at a temperature between about 800 and 900 F. and at a liquid hourly space velocity from about 2.0 to about 8.0 in the presence of a sulfided nickel-tungsten-halogen catalyst composited with a siliceous cracking base, which base has a cracking activity index above about 4'5, maintaining conversion (net make of gasoline plus middle oil B.P. 100- 675 F.) between about 20 and 50 percentwith a ratio of middle oil (400675 F.) to gasoline (C -400 F.) in the converted product of at least 2:1, subjecting the liquid portion of the product to distillation to separate a middle oil fraction having a boiling range in the range of 300 to 750 3 F., adding this fraction to a residual petroleum fraction and continuing said hydrogen treatment for a throughput of at least 1200 volumes of feed per volume of catalyst.

6. The hydrocracking process for preparing middle oils without substantially deactivating the catalyst which comprises subjecting a straight run heavy gas oil having less than 5 percent by volume of components boiling below about 675 F., containing at least about ppm. of nitrogenous compounds to treatment with hydrogen in an amount of at least 5000 s.c.f. of hydrogen per barrel of feed stock at a hydrogen partial pressure between about 400 and 1200 p.s.i., at a temperature between about 600 and 800 F. and at a liquid hourly space velocity from about 2.0 to about 8.0 in the presence of a sulfided nickel-tungsten-halogen catalyst composited with a siliceous cracking base, which base has a cracking activity index above about 45 for a period of time between about 8 and 24 hours, thereafter increasing the temperature to between about 800 and 900 F., and maintaining conversion (net make of gasoline plus middle oil B.P. 100675 F.) between about 20 and 50 percent with a ratio of middle oil (400675 F.) to gasoline (C -400 F.) in the converted product of at least 2: 1, subjecting the liquid portion of the product to distillation to separate a middle oil fraction having a boiling range in the range between about 350 and 675 F., adding part of this fraction to a straight run furnace oil, adding -a part of this fraction to a residual petroleum fraction and continuing said hydrogen treatment for a throughput of between about 1200 and 12,000 volumes of feed per volume of catalyst.

7. A process for producing a middle oil without substantially deactivating the catalyst boiling in the range from about 400 to about 675 F. which comprises subjecting a heavy gas oil having less than 5 percent by volume of components boiling below 675 F. and containing at least 100 ppm. of nitrogenous compounds to treatment with hydrogen in an amount of at least 5,000 standard cubic feet of hydrogen per barrel of feed stock in the presence of a sulfided nickel-tungstenhalogen catalyst composited with a silica-alumina cracking base, said nickel and tungsten being present in the approximate mol ratio of about 1:1, said nickel and tungsten combined comprising about 25 percent by weight of the total catalyst composite, said halogen being present in the amount of 2 percent by weight based on the total catalyst composite, said base being comprised of about 75 percent silica and about 25 percent by weight alumina and said base having a cracking activity index above about 45, at a hydrogen partial pressure between about 400 and 1200 p.s.i., at a temperature between about 800 and 900 F. and a liquid hourly space velocity from about 2.0 to about 8.0, maintaining conversion (100 percent minus percent by volume boiling above 675 F.) between about 20 and 50 percent and maintaining production of gasoline (C to 400 F.) at less than about 15 percent wherein the ratio of middle oil (400 F.-675 F.) to gasoline (C -400 F.) in the converted product is at least 2:1.

8. The process of claim 7 wherein the heavy gas oil contains at least 600 ppm. of nitrogenous compounds, the heavy gas oil is treated with at least 10,000 standard cubic feet of hydrogen per barrel of feed, the cracking base has an activity index above about 70, the liquid hourly space velocity is from about 3.0 to about 7.0, the conversion is between about 20 and 30' percent and the production of gasoline is less than 10 percent.

' 9. A process for producing a middle oil without substantially deactivating the catalyst boiling in the range from about 350 to about 675 F. which comprises subjecting a heavy gas oil having less than 5 percent by volume of components boiling below 675 F. and containing at least 100 ppm. of nitrogenous compounds to treatment with hydrogen in an amount of at least 5,000

standard cubic feet of hydrogen per barrel of feed stock in the presence of a sulfided nickel-tungsten-hal ogen catalyst composited with a silica-a1umina cracking base, said nickel and tungsten being present in the approximate mol ratio of about 1:1, said nickel and tungsten combined comprising about 25 percent by weight of the total catalyst composite, said halogen being present in the amount of 2 percent by weight based on the total catalyst composite, said base being comprised of about 75 percent silica and about 25 percent by weight alumina and said base having a cracking activity index above about 45, at a hydrogen partial pressure between about 400 and 1200 psi, at a temperature between about 800 and 900 F. and a liquid hourly space velocity from about 2.0 to about 8.0, maintaining conversion (100 percent minus percent by volume boiling above 675 F.) between about 20 and 50 percent and maintaining production of gasoline (C to 350 F.) at less than about 15 percent wherein the ratio of middle oil (350-675 F.) to gasoline (C5 350 F.) in the converted product is at least 2.5 :1.

10. The process of claim 9 wherein the heavy gas oil References Cited by the Examiner UNITED STATES PATENTS 2,839,450 6/1958 Oettinger 2081 10 2,932,611 4/1960 Scott et a1. 208-61 3,078,221 2/1963 Beuther et a1. 2081 11 3,099,617 7/1963 Tulleners 208--1l0 3,145,160 8/1964 Jacobson 208-110 3,172,838 3/1965 Mason et a1. 20861 DELBERT E. GANTZ, Primary Examiner.

20 ALPHONSO D. SULLIVAN, PAUL M. COUGHLAN,

Examiners.

A. RIMENS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Nox 3,268,43 August 23, 1966 Harold Beuther et a1.

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 6, In Table III, first column, line 4 thereof, for "aractezizatlon" read Characterization Signed and sealed this 26th day of September 1967.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents

Claims (1)

1. 2. THE HYDROCRACKING PROCESS FOR PREPARING A MIDDLE OIL WITHOUT SUBSTANTIALLY DEACTIVATING THE CATALYST WHICH COMPRISES SUBJECTING A FEED STOCK HAVING LESS THAN 5 PERCENT BY VOLUME OF COMPONENTS BOILING BELOW ABOUT 675*

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