Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G47/00—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions
  • C10G47/02—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions characterised by the catalyst used
  • C10G47/10—Cracking of hydrocarbon oils, in the presence of hydrogen or hydrogen- generating compounds, to obtain lower boiling fractions characterised by the catalyst used with catalysts deposited on a carrier
  • C10G47/12—Inorganic carriers
  • C10G47/16—Crystalline alumino-silicate carriers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
  • B01J29/084—Y-type faujasite

Definitions

• This invention relates to a catalytic hydrocracking process and a catalyst for use therein.
• the invention is particularly concerned with an improved process for producing middle distillate products using a catalyst highly selective for such products.
• Petroleum refiners often produce desirable products such as turbine fuel, diesel fuel, and other hydrocarbon liquids known as middle distillates as well as lower boiling liquids, such as naphtha and gasoline, by hydrocracking a hydrocarbon feedstock derived from crude oil.
• Feedstocks most often subjected to hydrocracking are gas oils and heavy gas oils recovered from crude oil by distillation.
• a typical gas oil comprises a substantial proportion of hydrocarbon components boiling above about 700° F., usually at least about 80 percent by weight boiling above 700° F.
• a typical heavy gas oil has a boiling point range between about 600° F. and 1050° F.
• Hydrocracking is generally accomplished by contacting, in an appropriate reaction vessel, the gas oil or other feedstock to be treated with a suitable hydrocracking catalyst under conditions of elevated temperature and pressure in the presence of hydrogen so as to yield a lower overall average boiling point product containing a distribution of hydrocarbon products desired by the refiner.
• a suitable hydrocracking catalyst is the prime factor in determining such yields.
• middle distillates are not in high demand relative to gasoline in the United States; however, marketing surveys indicate that there will be an increased demand for middle distillates as the year 2000 approaches. For this reason, refiners have recently been focusing on midbarrel hydrocracking catalysts which selectively produce middle distillate fractions, such as turbine fuel and diesel fuel, that boil in the 300° F. to 700° F. range.
• Activity may be determined by comparing the temperature at which various catalysts must be utilized under otherwise constant hydrocracking conditions with the same feedstock so as to produce a given percentage, normally about 60 percent, of products boiling below 700° F. The lower the activity temperature for a given catalyst, the more active such a catalyst is in relation to a catalyst of higher activity temperature.
• Selectivity of midbarrel or middle distillate hydrocracking catalysts may be determined during the foregoing described activity test and is measured as the percentage fraction of the 700° F.- product boiling in the desired midbarrel product range, e.g., 300° F. to 700° F. for diesel fuel and 300° F. to 550° F. for turbine fuel.
• Stability is a measure of how well a catalyst maintains its activity over an extended time period when treating a given hydrocarbon feedstock under the conditions of the activity test. Stability is generally measured in terms of the change in temperature required per day to maintain a 60 volume percent or other given conversion.
• U.S. Patents 4,062,809 and 4,419,271 disclose two different types of very effective middle distillate hydrocracking catalysts.
• the catalyst of U.S. Patent 4,062,809 contains molybdenum and/or tungsten plus nickel and/or cobalt on a support of silica-alumina dispersed in gamma alumina.
• Patent 4,419,271 teaches that the catalyst of U.S. Patent 4,062,809 can be improved by adding an aluminosilicate zeolite to the support, thereby producing a catalyst containing molybdenum and/or tungsten and nickel and/or cobalt supported on a mixture of an aluminosilicate zeolite, preferably an ultrahydrophobic zeolite such as LZ- 10 zeolite, and a dispersion of silica-alumina in a gamma alumina matrix.
• the presence of the zeolite in this catalyst increases the activity of the catalyst without significantly affecting the selectivity.
• middle distillate hydrocracking catalysts comprising one or more hydrogenation components and a Y zeolite having either a unit cell size below about 24.45 angstroms or a water vapor sorptive capacity less than about 10 weight percent at 25° C. and p/p 0 value of 0.10 can be substantially improved by incorporating an amorphous silica-magnesia component into the catalyst.
• the hydrocracking catalyst normally contains one or more hydrogenation components, such as one or more Group VIB or Group VIII metal components, in combination with the Y zeolite, the amorphous silica-magnesia component, and a porous, inorganic refractory oxide binder, such as alumina.
• p/p 0 represents the water vapor partial pressure to which the Y zeolite is exposed divided by the water vapor partial pressure at 25° C.
• the Y zeolite preferably has an overall silica-to-alumina mole ratio less than 6.0, usually between about 4.5 and 5.6.
• the catalyst also comprises a porous, inorganic refractory oxide binder.
• the Y zeolite which comprises the midbarrel hydrocracking catalyst of the invention has either (1) a unit cell size less than about 24.45 angstroms or (2) a sorptive capacity for water vapor at 25° C. and a p/p 0 value of 0.10 of less than 10 weight percent, preferably less than 5 weight percent.
• Preferred Y zeolites meet both of the foregoing requirements.
• the preferred Y zeolite for use in the hydrocracking catalyst of the invention is a UHP-Y zeolite, an ultrahydrophobic Y zeolite.
• the composition and properties of UHP-Y zeolites are disclosed in U.S. Patent 4,401,556 herein incorporated by reference in its entirety. See also Great Britain Patent 2 014 970 B which is also herein incorporated by reference in its entirety.
• UHP-Y zeolites and similar zeolites are, in essence, produced by a four step procedure in which a Y zeolite in the alkali metal form (usually sodium) and typically having a unit cell size of about 24.65 angstroms is cation exchanged with ammonium ions, calcined in the presence of water vapor (preferably in the presence of at least 0.2 psia water vapor, even more preferably at least 1.0 psia water vapor, and more preferably still, at least 10 psia water vapor, and most preferably of all, an atmosphere consisting essentially of or consisting of steam) so as to produce a unit cell size in the range of 24.40 to 24.64 angstroms, preferably 24.42 to 24.62 angstroms, then ammonium exchanged once again, and then calcined again in the presence of sufficient water vapor (preferably in an atmosphere consisting essentially of steam, and most preferably consisting of steam) so as to yield a unit cell
• the first ammonium exchange step typically reduces the sodium content of the starting sodium Y zeolite from a value usually greater than about 8.0 weight percent, usually between 10 and 13 weight percent, calculated as Na 2 0, to a value in the range between about 0.6 and 5 weight percent, while the second ammonium exchange further reduces the sodium content to less than about 0.5 weight percent, usually less than 0.3 weight percent.
• UHP-Y zeolites differ from the Y zeolite taught in U.S. Patent 3,929,672 by the addition of the final steam calcination step, some of the zeolites of said patent being known under the designations Y-82 or LZY-82 and Y-84 or LZY-84.
• UHP-Y zeolites have one or more of the following properties: an overall silica-to-alumina mole ratio from 4.5 to 35; a surface area of at least 350 m 2 /g; and a sorptive capacity for water vapor of less than 5 weight percent at 25° C. and a p/p 0 value of 0.10.
• UHP-Y zeolites having an overall silica-to-alumina mole ratio of 4.5 to 9 and/or a sorptive capacity for water vapor at 25° C. and a p/p 0 value of 0.10 of less than 4 weight percent.
• LZ-10 zeolite is the most preferred UHP-Y zeolite, LZ-10 zeolite being available from UOP.
• LZ-10 zeolite usually has a unit cell size or dimension at or above 24.20 angstroms, preferably between 24.20 and 24.40, and most preferably between about 24.25 and 24.35 angstroms, and has a water vapor sorptive capacity at 4.6 mm water vapor partial pressure and 25° C. less than 8.0 percent by weight of the zeolite. See U.S. Patent 4,419,271 which previously has been incorporated by reference in its entirety.
• the Y zeolites used in the catalyst of the invention are typically made by a process which involves two ammonium exchange steps to reduce the sodium or other alkali metal content of the starting Y zeolite to a value less than 0.5 weight percent sodium, usually less than about 0.3 weight percent, calculated as Na 0.
• These zeolites of reduced sodium content possess catalytic cracking activity and can be used as components of hydrocracking catalysts.
• the selectivity of catalysts containing these Y zeolites for middle distillate production can be substantially increased by ion exchanging the Y zeolites of reduced sodium content with rare earth-containing cations.
• the solution contains more than about 20 grams per liter of rare earth metal cations (calculated as RE 2 0 3 where RE is the sum of all rare earth metals under consideration, regardless of whether any one or more of such metals actually forms a trioxide of equivalent formula) , and the contacting is usually accomplished by immersing the zeolite into the ion- exchange solution and stirring at ambient temperature or above but usually at no more than about 100° C.
• the solution may also contain ammonium ions, and the solution may further contain any of a number of anions that will not interfere with the cation exchange, e.g. chloride, nitrate, sulfate, etc.
• the ion exchange is performed in a manner such that the rare earth-exchanged zeolite contains at least about 1 percent, preferably at least 2 percent, and usually between about 4 and 6 percent, by weight of rare earth metals, calculated as RE 2 0 3 .
• the rare earth metals exchanged into the zeolite will replace some of the residual sodium ions at exchange sites in the zeolite, the largest proportion will exchange with hydrogen ions and/or ammonium ions because of their relatively high concentration versus the low concentration, usually below 0.3 weight percent, calculated as Na 2 0, of sodium cations present.
• Y zeolite to be used in the catalyst of the invention is combined with a binder material to form support particles which serve to carry one or more hydrogenation components.
• this is accomplished by combining the Y zeolite with (1) a material such as an alumina hydrogel or peptized alumina, which, upon calcination, will yield a porous, inorganic refractory oxide binder or (2) a material which itself is a porous, inorganic refractory oxide binder, for example, alumina, silica-alumina, a clay, such as kaolin, as well as physical and chemical combinations of such materials.
• a sufficient amount of the Y zeolite is normally used such that the support comprises between about 2 and 35 weight percent, preferably between about 3 and 20 weight percent, more preferably between about 5 and 10 weight percent, of the Y zeolite.
• the most convenient method for physically integrating the zeolite and the binder is to comull the porous, inorganic refractory oxide binder or precursor material with the zeolite, and subsequently extrude the comulled material through a die having small openings therein of desired cross-sectional size and shape, e.g., circle, trilobal clover-leaf, quadralobal clover leafs, etc., breaking or cutting the extruded matter into appropriate lengths, e.g., 1/16 to 3/4 inch, drying the extrudates, and then calcining at a temperature between 800° F. and 1200° F. to produce a material suitable for use in high temperature hydrocracking reactions.
• desired cross-sectional size and shape e.g., circle, trilobal clover-leaf, quadralobal clover leafs, etc.
• the support be produced in cylindrical form; however, as stated above, other cross-sectional shapes are possible, such as cloverleafs of polylobal design, for example, trilobal or quadralobal shapes, as shown, for example, in Figures 8 and 10, respectively, in U.S. Patent 4,028,227 herein incorporated by reference in its entirety.
• porous, inorganic refractory oxide is used as a binder material to hold the Y zeolite particles together in the support.
• Other materials are normally also incorporated into the comulled mixture, including for example, amorphous, inorganic refractory oxide diluents, which may or may not possess some type of catalytic activity.
• amorphous, inorganic refractory oxide diluents which may or may not possess some type of catalytic activity.
• the silica-magnesia component used in the catalyst of the invention may be prepared by methods generally well known in the art.
• One such method involves first forming a silica hydrogel by precipitating silica from an aqueous solution of a silicate salt, such as an alkali or alkaline earth metal silicate, or silicic acid by reducing the solution pH, usually by the addition of inorganic acids such as hydrochloric, nitric, and sulfuric.
• a silicate salt such as an alkali or alkaline earth metal silicate, or silicic acid by reducing the solution pH, usually by the addition of inorganic acids such as hydrochloric, nitric, and sulfuric.
• the resultant silica hydrogel is washed and then soaked in a solution of a magnesium salt in proportions sufficient to provide the desired relative amounts of magnesia and silica in the final silica-magnesia composi- tion.
• Examples of water-soluble magnesium salts which can be used to make the magnesium solutions include magnesium chloride, magnesium nitrate, magnesium sulfate, magnesium acetate, magnesium bromide, magnesium iodide and the like.
• magnesia is precipitated in situ by adding a base, such as ammonia, ammonium hydroxide and sodium hydroxide, to increase the solution pH.
• a base such as ammonia, ammonium hydroxide and sodium hydroxide
• the silica-magnesia component can be created by mulling magnesium oxide with a dried silica hydrogel. When mulling is used, more effective interaction of the silica and magnesia is obtained if water is present in sufficient quantities to form a coherent paste. The paste is then dried and calcined to form the silica- magnesia component.
• the amount of silica and magnesia in the silica- magnesia component can vary considerably, but usually at least 5 weight percent magnesia based on the combined weight of silica and magnesia is present.
• the silica-magnesia component contains between about 65 and 75 weight percent silica and between about 25 and 35 weight percent magnesia.
• the catalyst support may also be produced in tablet, granules, spheres, and pellets as desired, by any known method for combining zeolites with porous, inorganic refractory oxide components. Regardless of how the support particles are produced, they typically contain between about 5 and 40, preferably from about 10 to 25, weight percent binder and between about 25 and 90, usually between about 40 and 80, weight percent amorphous silica-magnesia..
• the catalyst support particles are converted to catalyst particles by com ⁇ pounding, as by impregnation of the particles, with one or more precursors of at least one catalytically active hydrogenation metal component.
• the impregnation may be accomplished by any method known in the art, including spray impregnation wherein a solution containing the hydrogenation metal precursors in dissolved form is sprayed onto the support particles.
• Another method involves soaking the support particles in a large volume of the impregnation solution.
• Yet another method is the pore volume or pore saturation technique wherein the support particles are introduced into an impregnation solution of volume just sufficient to fill the pores of the support.
• the pore saturation technique may be modified so as to utilize an impregnation solution having a volume between 10 percent less and 10 percent more than that which would just fill the pores.
• an impregnation solution having a volume between 10 percent less and 10 percent more than that which would just fill the pores.
• a subsequent or second calcination as for example at temperatures between 700° F. and 1200° F., will convert the metals to their respective oxide forms. In some cases, calcinations may follow each impregnation of individual active metals.
• Alternative methods of introducing the active metal components into the catalyst support include (l) mixing an appropriate solid or liquid containing the metal components with the materials to be extruded through the die and (2) impregnating the materials to be extruded with the desired metal components prior to carrying out the extrusion. Such methods may prove less expensive and more convenient than the impregnation methods discussed above and will also result in the active hydrogenation components being intimately mixed with the components of the support.
• Hydrogenation components suitable for incor ⁇ poration into the extruded catalyst support particles comprise metals selected from Group VIII and/or Group VIB of the Periodic Table of Elements.
• Periodic Table of Elements refers to the version found in the inside front cover of the Handbook of Chemistry and Physics, 65th Edition, published in 1984 by the Chemical Rubber Company, Cleveland, Ohio.
• Preferred hydrogenation components comprise metals selected from the group consisting of platinum, palladium, cobalt, nickel, tungsten, chromium, and molybdenum.
• the catalyst contains at least one Group VIII metal component and at least one Group VIB metal component, with cobalt or nickel and molybdenum or tungsten being preferred combinations of active components and nickel and tungsten being most preferred.
• the catalyst typically contains up to about 15, usually between about 1 and 10 weight percent, preferably between 2 and 8 weight percent, of a non-noble Group VIII metal, calculated as the monoxide, and up to 30, usually from about 2 to 28 weight percent, and preferably between about 10 and 25 weight percent, of the Group VIB metal, calculated as the trioxide.
• the hydrogenation component comprises a noble metal such as platinum or palladium, it is generally desired that the catalyst contain between about 0.2 and about 10 weight percent, preferably between about 0.30 and 2.0 weight percent, calculated as the metal.
• catalysts with the hydrogenation metals present in the oxide form are prepared as particulates.
• the finished hydrocracking catalysts typically have a BET surface area ranging between about 100 and 350 m 2 /g.
• these catalysts usually comprise (1) between about 2 and 25 weight percent, preferably between about 3 and 15 weight percent, and more preferably between about 4 and 8 weight percent, Y zeolite having a unit cell size below about 24.45 angstroms and/or a water vapor sorptive capacity less than about 10 weight percent at 25° C.
• Catalysts prepared in the oxide form as described above are generally converted to the sulfide form for hydrocracking purposes when non-noble metals are used as hydrogenation components. This can be accomplished by presulfiding the catalyst prior to use at an elevated temperature, e.g., 300° to 700° F., with, for example, a mixture consisting of 10 volume percent H 2 S and 90 volume percent H 2 .
• the catalyst can be presulfided ex situ by various sulfiding processes; as an illustration, see "Sulficat R : Off-Site Presulfiding of Hydroprocessing Catalysts from Eurecat" by J.H. Wilson and G. Berrebi, Catalysis 87.
• the sulfiding is accomplished in situ, i.e., by using the catalyst in the oxide form to hydrocrack a hydrocarbon feedstock containing sulfur compounds under hydrocracking conditions, including elevated temperature and pressure and the presence of hydrogen.
• the feedstocks described above are hydrotreated before being subjected to the hydrocracking process of the invention.
• the hydrotreating is performed in conjunction with hydrocracking, usually by a method referred to as "integral operation."
• the hydrocarbon feedstock is introduced into a catalytic hydro ⁇ treating zone wherein, in the presence of a suitable catalyst and under suitable conditions, including an elevated temperature (e.g., 400° to 1000° F.) and an elevated pressure (e.g., 100 to 5000 p.s.i.g.) and with hydrogen as a reactant, the organonitrogen components and the organosulfur components contained in the feedstock are converted to ammonia and hydrogen sulfide, respectively.
• an elevated temperature e.g., 400° to 1000° F.
• an elevated pressure e.g., 100 to 5000 p.s.i.g.
• Suitable hydrotreating catalysts include zeolite- or molecular sieve-free, particulate catalysts comprising a Group VIII metal component and a Group VIB metal component on a porous, inorganic, refractory oxide support most often composed of alumina.
• the entire effluent removed from the hydrotreating zone is subsequently treated in the hydrocracking zone maintained under suitable conditions of elevated temperature, pressure, and hydrogen partial pressure, and containing the hydrocracking catalyst of the invention.
• the hydrotreating and hydrocracking zones in integral operation are maintained in separate reactor vessels, but, on occasion, it may be advantageous to employ a single, downflow reactor vessel containing one or more upper beds of the hydrotreating catalyst particles and one or more lower beds of the hydrocracking catalyst particles.
• the catalyst of the invention is usually employed as a fixed bed of catalytic extrudates in a hydrocracking reactor into which hydrogen and the feedstock are introduced and passed in a downwardly direction.
• the reactor vessel is maintained at conditions so as to convert the feedstock into the desired product, which is normally a hydrocarbon product containing a substantial portion of turbine fuel and diesel fuel components boiling in the range between 300° F. and 700° F.
• the temperature of the reaction vessel is maintained between about 450° F. and about 850° F. , preferably between about 500° F. and 800° F.
• the pressure normally ranges between about 750 p.s.i.g. and about 3500 p.s.i.g., preferably between about 1000 and about 3000 p.s.i.g.
• the liquid hourly space velocity (LHSV) is typically between about 0.3 and 5.0, preferably between about 0.5 and 3.0, reciprocal hours.
• the ratio of hydrogen gas to feedstock utilized usually ranges between about 1,000 and 10,000 standard cubic feet per barrel, preferably between about 2,000 and 8,000 standard cubic feet per barrel, as measured at 60° C. and 1 atmosphere.
• the typical gas oil feedstock contains no more than about 35 volume percent, usually less than 15 volume percent, constituents boiling in the 300° F. to 700° F. range.
• the hydrocracking operation conditions are chosen so that at least about 80 volume percent, preferably at least about 86 volume percent, and more preferably yet at least about 87 volume percent, of the 700° F.- product boils in the range between 300° F. and 700° F.
• the 700° F.- product contains greater than about 76 volume percent, preferably at least about 78 volume percent, and more preferably greater than about 79 volume percent, hydrocarbons boiling in the range between 300° F. and 550° F.
• the catalyst of the present invention as compared to a highly successful commercial middle distillate hydrocracking catalyst containing a dispersion of silica-alumina particles in a gamma alumina matrix in lieu of an amorphous silica- magnesia component provides for enhanced results when used to selectively produce turbine and diesel f el.
• the catalyst of the invention provides for significant increases in the yield of hydrocarbon distillates boiling in the 300° F. to 550° F. range and the 300° F. to 700° F. range.
• Catalyst 1 Catalyst 1, a catalyst of the invention was prepared by mixing 5 weight percent LZ-10 zeolite, 75 weight percent amorphous silica-magnesia (SM-30 silica- magnesia obtained from the Davison Chemical Division of W. R. Grace and Company) , which contained about 70 weight percent silica and about 30 weight percent magnesia, and 20 weight percent peptized Catapal alumina binder.
• the LZ-10 zeolite which was obtained from UOP, had a unit cell size of about 24.30 angstroms, an effective pore size above about 7.0 angstroms and an overall silica-to-alumina mole ratio of about 5.2.
• the wetted mixture was mulled and then extruded through a 1/16-inch cylindrical die to form cylindrical extrudates that were cut into 1/8 to 1/2 inch lengths.
• the extrudates were dried at 100° C. and then calcined at 900° F.
• the dried and calcined extrudates were then impregnated by the pore saturation method with an aqueous solution containing nickel nitrate and ammonium metatungstate in sufficient quantities such that, after the impregnated extrudates were dried at 100° C. and calcined at 900° F.
• the resultant catalyst particles contained about 5 weight percent nickel, calculated as NiO, and about 22 weight percent tungsten, calculated as W0 3 , on a support consisting of 5 weight percent LZ-10 zeolite, 75 weight percent silica-magnesia, and 20 weight percent alumina binder.
• Catalyst 2 Catalyst 2 , a comparative catalyst, was prepared similarly to Catalyst 1 except that amorphous gamma alumina was used in lieu of the amorphous silica-magnesia.
• the finished catalyst contained the nickel and tungsten in the proportions above specified for Catalyst 1 on a support consisting of 5 weight percent LZ-10 zeolite, 75 weight percent amorphous gamma alumina, and 20 weight percent alumina binder.
• Catalyst 3 Catalyst 3, another comparative catalyst, was prepared similarly to Catalyst 1 except that an amorphous silica-alumina containing about 75 weight percent silica and about 25 weight percent alumina was used instead of the amorphous silica-magnesia.
• the finished catalyst contained the nickel and tungsten in the proportions specified for Catalyst 1 on a support consisting of 5 weight percent LZ- 10 zeolite, 75 weight percent amorphous silica-alumina and 20 weight percent alumina binder.
• Catalyst 4 Catalyst 4, another comparative catalyst, was prepared similarly to Catalyst 1 except that a dispersion of silica-alumina particles in a gamma alumina matrix (Aero 5545 obtained from Criterion Catalyst Company L.P.) was substituted for the amorphous silica-magnesia. The dispersion was amorphous and contained about 55 weight percent alumina and about 45 weight percent silica.
• the finished catalyst contained nickel and tungsten in the proportions specified for Catalyst 1 on a support consisting of 5 weight percent LZ-10 zeolite, 75 weight percent amorphous dispersion of silica-alumina in gamma alumina, and 20 weight percent alumina binder.
• Catalyst 5 is a sample of a commercial middle distillate hydrocracking catalyst obtained from UOP. It was prepared similarly to Catalyst 4 except it contained about 7 weight percent nickel, calculated as NiO, 10 weight percent LZ-10 zeolite, and 70 weight percent of the amorphous dispersion of silica-alumina particles in a gamma alumina matrix used in Catalyst 4.
• the catalyst contained about 7 weight percent nickel, calculated as NiO, and about 22 weight percent tungsten, calculated as W0 3 , on a support consisting of 10 weight percent LZ-10 zeolite, 70 weight percent dispersion of silica-alumina particles in a gamma alumina matrix, and 20 weight percent alumina binder.
• Catalyst 6 was prepared similarly to Catalyst 1, except 10 weight percent LZ-10 zeolite and 70 weight percent of the same silica-magnesia were used.
• the finished catalyst contained about 5 weight percent nickel, calculated as NiO, and about 22 weight percent tungsten, calculated as W0 3 , on a support consisting of 10 weight percent LZ-10 zeolite, 70 weight percent silica-magnesia, and 20 weight percent alumina binder.
• Each of the above-described six catalysts was presulfided by passing a gas stream consisting of 10 volume percent hydrogen sulfide and the balance hydrogen through a bed of the catalyst at a temperature initially of about 300° F. and slowly increased to 700° F. and held at that temperature for about one hour.
• the six catalysts were then tested for activity and selectivity in middle distillate hydrocracking using a hydrotreated light Arabian vacuum gas oil having an API gravity of 37°, an initial boiling point of 436° F. , a final boiling point of 1073° F. and a 50 percent boiling point of 813° F., with about 20 volume percent boiling below about 698° F. and 5 volume percent boiling below 588° F., as determined by a modified ASTM D1160 distillation.
• the vacuum gas oil was passed on a once- through basis through an isothermal reactor containing about 140 ml of the catalyst mixed with 95 ml of six to eight mesh quartz.
• Catalysts 1 through 4 which differ only in the amorphous component of their supports, all have about the same activity, i.e., 729° F. to 732° F.
• Catalyst 1 the catalyst of the invention, has much superior and unexpected selectivities to turbine and diesel fuel.
• the differences in selectivities to turbine fuel range from a high of 8.3 volume percent (79.4 - 71.1) between Catalysts 1 and 4 to a low of 5.2 volume percent (79.4 - 74.2) between Catalysts 1 and 3.
• Catalyst 1 A comparison of Catalyst 1 with Catalyst 5, a commercial catalyst which differs from Catalyst 1 by containing 5 weight percent more LZ-10 zeolite and 70 weight percent dispersion of silica-alumina in alumina instead of 75 weight percent silica-magnesia, indicates that Catalyst 1 is 10° F. less active (729° F. - 719° F.) than Catalyst 5. This lower activity is expected since Catalyst 1 contains less zeolite than Catalyst 5. However, Catalyst 1 is much more selective. According to the data, Catalyst 1 yields 8.1 volume percent (79.4 - 71.3) more turbine fuel boiling in the range between 300° F.
• Catalyst 1 A comparison of Catalyst 1 with Catalyst 6, which differs from Catalyst 1 in containing 5 weight percent more LZ-10 zeolite and 5 weight percent less silica-magnesia, indicates, as would be expected due to its increased zeolite content, that Catalyst 1 is 10° F. less active (729° F. - 719° F.).
• a comparison of the selectivity data for both catalysts shows that Catalyst 1 is much more selective with respect to both turbine fuel (79.4 volume percent vs. 70.3 volume percent) and diesel fuel (89.8 volume percent vs. 82.1 volume percent) .
• catalysts of the invention will have supports which contain between about 2 and 9 weight percent Y zeolite, preferably between 3 and 8 weight percent, and between 70 and 90 weight percent silica-magnesia, preferably 75 to 85 weight percent.

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