Technical Field

This invention relates to hydrocarbon conversion processes and catalysts for use therein. More particularly, it relates to a hydrocracking catalyst of improved activity, selectiv¬ ity, and stability for producing middle distillates from heavy gas oils and the like under hydrocracking conditions.

Background Art

Petroleum refiners often produce desirable products as turbine fuel, diesel fuel, and other middle distillate products by hydrocracking a heavy gas oil, i.e., a hydro¬ carbon fraction having a boiling point range between about 700° F. and 1050° F. (371° and 566 °C). Hydrocracking is accomplished by contacting the heavy gas oil at an elevated temperature and pressure in the presence of hydrogen and a suitable hydrocracking catalyst so as to yield a middle distillate fraction boiling in the 300° to 700° F. (149° to 371° C. ) range and containing the desired turbine and diesel fuels. The three main catalytic properties by which the per¬ formance of a hydrocracking catalyst for producing middle distillate products is evaluated are activity, selectivity, and stability. 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 (usually 60%) of the products boiling below 700° F. (371 °C). The lower the activity temperature for a given catalyst,

the more active such a catalyst is in relation to a cata¬ lyst of higher activity temperature. Selectivity of hydrocracking catalysts may be determined during the fore¬ going described activity test and is measured as that per- centage fraction of the 700° F.-minus (371° C.-minus) product boiling in the range of middle distillate or mid¬ barrel products, i.e., 300° to 700° F. (149° to 371° C.) . 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% or other given conversion.

As could be expected, the aim of the art is to provide a catalyst having at once the highest possible activity, selectivity, and stability. Catalysts usually utilized for hydrocracking comprise a Group VIII metal component, most often cobalt or nickel sulfides, in combination with a Group VIB metal component, most often molybdenum or tung- sten sulfides, supported on a refractory oxide. For given proportions of Group Vlir and Group VIB metal components, the activity, selectivity, and stability of a catalyst change dramatically with different supports. Support mate¬ rials comprising crystalline aluminosilicate zeolites, such as Zeolite Y in the hydrogen form, generally provide high activity but low selectivity, whereas support materials consisting essentially of refractory oxides, such as alu¬ mina, magnesia, and silica-alumina, generally have relative¬ ly poor activity but high selectivity. The object of the present invention, therefore, is to provide a hydrocracking catalyst having superior overall catalytic properties for hydrocracking hydrocarbons. More specifically, it is an object of the invention to provide a catalyst having superior overall activity, selectivity, and stability for hydrocracking in comparison to prior art catalysts. It is a further object to provide a hydro¬ cracking process for converting gas oils and the like to

middle distillate products. It is a further object to provide a support or carrier material useful with hydro¬ genation components as a catalyst for hydrogenating and/or hydrocracking hydrocarbons. These and other objects and advantages will become more apparent in light of the following description of the invention.

Disclosure of Invention

The present invention is an improvement of the cata¬ lyst described in U.S. Patent No. 4,097,365, herein incor- porated by reference. The catalyst described in this patent is a midbarrel hydrocracking catalyst comprising hydrogenation components on a refractory oxide support comprising silica-alumina dispersed in a matrix of alumina. The present invention improves this catalyst by including in the support a crystalline aluminosilicate zeolite having cracking' activity, such as hydrogen Y zeolite o a rare earth-exchanged Y zeolite. In■ addition to having excellent activity for hydrodenitrogenation and hydrodesulfurization, the catalyst of the invention has been found to have superior overall properties of activity, selectivity, and stability for hydrocracking in comparison to the catalyst described in U.S. Patent No. 4,097,365. In the usual instance, the catalyst of the invention is more.active, more stable, and more selective than comparison catalysts having supports consisting essentially of either a disper¬ sion of silica-alumina in an alumina matrix or a zeolite plus a refractory oxide other than a dispersion of silica- alumina in an alumina matrix.

In its broadest embodiment, the present invention provides a catalyst support comprising in intimate admix¬ ture (1) a crystalline aluminosilicate zeolite having cracking activity and (2) a dispersion of silica-alumina in an alumina matrix. Although the support is most pre¬ ferred when used in conjunction with a hydrogenation co - ponent, it may itself be utilized in the absence of a hydrogenation component as a catalyst for converting

hydrocarbons to more valuable products by acid catalyzed reactions, such as catalytic cracking, isomerization of n-paraffins to isoparaffins, isomerization of alkyl aro- matics, alkylation, and transalkylation of alkyl aromatics. In view of the foregoing, it can be seen that the invention in alternative embodiments is directed to improved catalytic hydrocracking, hydrodenitrogenation, or hydrodesulfurization processes wherein the improvement resides in the use of a catalyst comprising hydrogenation components on a refractory oxide support comprising a heterogeneous mixture of (1) a crystalline aluminosilicate zeolite having activity for catalytically cracking hydro¬ carbons and (2) a dispersion of silica-alumina in a gamma alumina matrix. In still other alternative embodiments, the invention is directed to improved catalytic cracking, catalytic isomerization, catalytic alkylation, and cata¬ lytic transalkylation processes wherein the improvement is the use of a catalyst comprising- both a crystalline aluminosilicate zeolite having cracking activity and a dis- persion of silica-alumina in an alumina matrix in intimate heterogeneous admixture.

Modes, Including Best Mode, For Carrying .Out the Invention The catalyst of the invention is an intimate composite of one or more hydrogenation components, a crystalline aluminosilicate zeolite having catalytic activity for cracking hydrocarbons, and a dispersion of silica-alumina in a matrix consisting essentially of alumina. The hydro¬ genation components useful in the invention are the metals, oxides, and sulfides of uranium, the Group VIII elements, and the Group VIB elements. The most suitable hydrogen¬ ation components are selected from the group consisting of the metals, oxides, and sulfides-of platinum, palladium, cobalt, nickel, tungsten, and molybdenum. The preferred catalyst contains at least one Group VIII metal component, and at least one Group VIB metal component, with the most preferred combination being a nickel and/or cobalt

component with a molybdenum and/or tungsten component.

The hydrogenation component or components are inti¬ mately composited on a base or support comprising a mix¬ ture of one or more crystalline aluminosilicate zeolites having cracking activity and a heterogeneous dispersion of finely divided silica-alumina in a matrix of alumina. The suitable zeolites for use herein include crystalline aluminosilicate molecular sieves having catalytic activity for cracking hydrocarbons. Many naturally occurring and synthetic crystalline aluminosilicate zeolites known in the art are useful in the invention, including, for example, faujasite, mordenite, erionite, Zeolite Y, Zeolite X, Zeolite L, Zeolite Omega, Zeolite ZSM-4, and their modifi¬ cations. These and other such zeolitic molecular sieves are known to have activity for cracking hydrocarbons when a substantial proportion of the ion exchange sites are occupied with hydrogen ions or multivalent metal-containing cations, particularly rare earth cations. Normally, crys¬ talline .aluminosilicate zeolites are obtained in the alkali metal form and as such are largely inactive for catalyti- cally cracking hydrocarbons. To produce a zeolite having • cracking activity, the alkali metals are usually replaced with multivalent metal-containing cations, hydrogen ions, or hydrogen ion precursors (e.g. ammonium ion). This replacement of cations is generally accomplished by ion exchange, a method well-known in the art wherein the zeolite in the sodium or other alkali metal form is con¬ tacted with an aqueous solution containing hydrogen ions, ammonium ions, rare earth ions, or other suitable cations. Replacing even a portion of the sodium ions produces a zeolite having some cracking activity, but reducing the alkali metal content to less than 5 wt.%, preferably to less than 1 wt.%, and most preferably to less than about 0.5 wt.% (calculated as the alakali metal oxides), results in a material having substantial cracking activity, with the activity varying according to the zeolite and the amount of alkali metals removed.

In addition to the zeolites referred to above, many other crystalline aluminosilicate zeolites in their non- alkali metal forms may be utilized in the catalyst support of the invention. Preferred zeolites contain at least 50% of their pore volume in pores of diameter greater than

8 Angstroms, with Zeolite Y (and its modifications) in the hydrogen form or in other forms imparting cracking activity to the zeolite being preferred zeolites for use in the invention. Also preferred are zeolites that have been ion- exchanged with ammonium ions and then steam stabilized in accordance with the teachings of U.S. Patent No. 3,929,672, herein incorporated by reference. The most highly preferred zeolite is a material known as LZ-10, a zeolitic molecular sieve available from Union Carbide, Linde Division. Although LZ-10 is a proprietary material, it is known that LZ-10 is a modifiedY zeolite having a silica to alumina ratio between about 3.5 and 4.0, a surface area between about 500 and 700 m^/gm, a unit cell size between- about 24.25 and 24.35 Angstroms, water absorption capacity less than about 8% by weight of the zeolite (at 4.6 mm partial pressure of water vapor and 25° C), and an ion-exchange capacity less than 20% of that of a sodium Y zeolite of comparable silica to alumina ratio. When used as a hydro¬ cracking catalyst, LZ-10 is highly active and selective for midbarrel hydrocracking, especially when composited with alumina and suitable hydrogenation components.

The support material utilized in the invention usually comprises between 2 and about 80% by weight, preferably between about 10 and about 70% by weight, of a crystalline aluminosilicate zeolite such as LZ-10. The support also comprises a substantial proportion of a heterogeneous dis¬ persion of finely divided silica-alumina in an alumina matrix. Usually, the dispersion comprises at least 15% by weight of the support, with the preferred and most prefer- red proportions being in the respective ranges of 30 to 98% and 30 to 90% by weight of the support.

One convenient method of preparing the catalyst support herein is to comull an aluminua hydrogel with a silica- alumina cogel in hydrous or dry form. The cogel is prefer¬ ably homogeneous and may be prepared in a manner such as that described in U.S. Patent No. 3,210,294. Alternatively, the alumina hydrogel may be comulled with a "graft copolymer" of silica and alumina that has been prepared, for example, by first impregnating a silica hydrogel with an alumina salt and then precipitating alumina gel in the pores of the silica hydrogel by contact with ammonium hydroxide. In the usual case, the cogel or copolymer (either of which usually comprises silica in a proportion by dry weight of 20 to 96%, preferably 50 to 90%) is mulled with the alumina hydrogel such that the cogel or copolymer comprises 5 to 75% by weight, preferably 20 to 65% by weight, of the mixture. The overall silica content of the resulting dispersion on a dry basis is usually between 1 and 75 wt.%, preferably between 5 and 45 wt.%.

The mulled mixture of alumina gel with either a silica- alumina cogel or a silica and alumina "graft copolymer" may be utilized in the gel form or may be dried and/or calcined prior to combination with the zeolite. In the preferred method of preparation, the cogel or copolymer is spray dried and then crushed to a powdered form, following which the powder is mulled with a zeolite powder containing hydrogen ions, hydrogen ion precursors, or multivalent metal-contain¬ ing cations, the amounts of cogel or copolymer mulled with said zeolite being such that the support will ultimately contain zeolite and dispersion in the proportions set forth hereinbefore. If desired, a binder may also be incorporated into the mulling mixture, as also may one or mere active metal hydrogenation components in forms such as ammonium heptamolybdate, nickel nitrate or chloride, air— niu meta- tungstate, cobalt nitrate or chloride, etc. After mulling, the mixture is extruded through a die having s ±able openings therein, such as circular openings of diameters between about 1/32 and 1/8 inch (0.08 to 0.32 cm.). Preferably,

however, the die has openings therein in the shape of three- leaf clovers so as to produce an extrudate material similar to that shown in Figures 8 and 8A of U.S. Patent No. 4,028,227. The extruded material is cut into lengths of about 1/32 to 3/4 inch (0.08 to 1.91 cm.), preferably 1/4 to 1/2 inch (0.64 to 1.27 cm.), dried, and calcined at an elevated temperature.

If desired, hydrogenation components may be composited with the support by impregnation; that is, rather than co- mulling the hydrogenation components with the support materials, the zeolite and dispersion are mulled, extruded, cut into appropriate lengths, and calcined. The resulting particles are then contacted with one or more solutions con¬ taining the desired hydrogenation components in dissolved form, and the composite particles thus prepared are dried and calcined to produce finished catalyst particles.

Usually, the finished catalyst contains at least about 0.5 wt.% of hydrogenation components, calculated as the metals. In the usual instance, wherein a Group VIII ^' metal and a Group VIB metal component are utilized in combination, the finished catalyst contains between about 5% and 35%, preferably between about 10 and 30% by weight, calculated as the respective trioxides, of the Group VIB metal compo¬ nents and between about 2% and 15%, preferably between 3 and 10% by weight, calculated as the respective monoxides, of the Group VIII metal components.

If desired, a phosphorus component may also be incor¬ porated in the catalyst by either comulling the support materials with phosphoric acid or including phosphoric acid in the impregnating solution. Usual and preferred propor- tions of phosphorus in the catalyst fall in the ranges of 1 to 10 wt.% and 3 to 8 wt.%, calculated as P2θ ₅ -

The hydrogenation components, which will largely be present in their oxide forms after calcination in air, may be converted to their sulfide forms, if desired, by contact at elevated temperatures with a reducing atmosphere com¬ prising hydrogen sulfide. More conveniently, the catalyst is sulfided in situ, i.e., by contact with a sulfur-

containing feedstock to be catalytically converted to more valuable hydrocarbons in such processes as hydrocracking, hydrotreating, etc.

The foregoing described catalysts are especially useful for hydrogenation reactions, such, as hydrodenitrogenating and hydrodesulfurizing hydrocarbons, but are particularly useful with respect to hydrocracking to convert a hydro¬ carbon feedstock to a more valuable product of lower average boiling point and lower average molecular weight. The feedstocaks that may be treated herein by hydrogenation include all mineral oils and synthetic oils (e.g., shale oil, tar sand products, etc.) and fractions thereof. Typical feedstocks include straight run gas oils, vacuum gas oils, deasphalted vacuum and atmospheric residua, coker distillates, and catcracker distillates. Preferred hydrocracking feedstocks include gas oils and other hydro¬ carbon fractions having at least 50% by weight-of their components boiling above 700° F. (371° C). Suitable and preferred conditions for hydrocracking gas oil feedstocks, as well as for hydrodenitrogenating and/or hydrodesulfur¬ izing such feedstocks are:

TABLE I

Suitable Pre erred

Temperature, °F. (°C.) 500-850 (260-454) 600-800 (316-427) Pressure, psig 750-3500 1000-3000 at 51-234 68-201

LHSV 0.3-5.0 0.5-3.0

H ₂ /Oil*, MSCF/bbl 1-10 2-8 cc/ml 178-1781 356-1425 *as measured at 60° F. (15.6° C.)

As will be shown by the following Examples, which are provided for illustrative purposes and are not to be con¬ strued as limiting the scope of the invention as. defined by the claims, the present catalysts have been found to possess superior overall catalytic properties when conversion of gas oils to midbarrel products by hydrocracking is desired. In

many instances, the catalysts of the inyention have been found to be superior in each of the three main performance categories of activity, selectivity, and stability. Example I 5 An experiment was performed to compare the activity, selectivity, and stability of catalysts of the invention containing LZ-10 and a dispersion of silica-alumina in a gamma alumina matrix versus catalysts having supports con¬ sisting essentially of LZ-10 and gamma alumina. Following

10 are the preparation procedures used for Catalyst Nos. 1 through 4, with Catalyst Nos. 2 and 3 being representative of the invention and Catalyst Nos. 1 and 4 being the com¬ parison catalysts. Catalyst No. 1

15 A mixture of 10% by weight powdered LZ-10 that had been ion-exchanged with ammonium nitrate to reduce the sodium content to about 0-1% by weight sodium (as Na~0) and 90% by weight gamma alumina was extruded through a die having opening therein in a three-leaf clover shape, each leaf

20 being defined by about a 270° arc of a circle having a diameter between about 0.02 and 0.04 inches (0.05 to 0.10 cm.) . The extruded material was cut into 1/4-1/2 inch (0.64 to 1.27 cm.) lengths and calcined at 900° F. (482° C.) in air to convert the LZ-10 material to the hydrogen form.

25 The calcined particles (300 gm) were then impregnated with 330 ml of an aqueous solution containing 67 gm of nickel nitrate (Ni(NO3) -y - 6H2O) and 108 gm of ammonium metatungstate (91% WO3 by weight) . After removing excess liquid, the catalyst was dried at 230° F. (110° C.) and calcined at

30 900° F. (482° C.) in flowing air. The final catalyst con¬ tained 4.4 wt.% nickel components (calculated as NiO) and 25.0 wt.% tungsten components (calculated as WO3) .

~" ' Catalyst No. 2

The procedure described for Catalyst No. 1 was repeated

35 except that in place of alumina a dispersion of spray dried, powdered silica-alumina in alumina prepared in a manner similar to that of Example 3 of U.S. Patent No. 4,097,365

ii was used. The dispersion was prepared by mixing 44 parts by dry weight of a 75/25 silica-alumina graft copolymer and 56 parts by weight of hydrous alumina gel. In the final catalyst the support consisted essentially of 10% LZ-10 in the hydro- gen form and 90% dispersion of silica alumina in an alumina matrix, the dispersion consisting overall of 33% by weight silica and 67% by weight alumina. The resulting catalyst contained 4.1% by weight nickel components (as NiO) and 24.2% by weight tungsten components (as WO3) - Catalyst No. 3

This catalyst was prepared in the same manner as Catalyst No. 2 except that the proportions of LZ-10 and dispersion ad¬ mixed to prepare the support were adjusted so that in the final catalyst the proportion of LZ-10 in the support was 5% by weight and that of the dispersion, 95% by weight. The final catalyst contained 4.1% by weight nickel components (as NiO) and 23.6% by weight tungsten components (as WO3) on a support of 5% LZ-10 and 95% dispersion. Catalyst No. 4 This catalyst was prepared in the same manner as Catalyst No. 1 except that the proportions of LZ-10 and alumina admixed during preparation were such that in the final catalyst the proportion of LZ-10 in the support was 20% by weight and that of the gamma alumina, 80% by weight. The final catalyst con- tained 4.1% by weight nickel components (as NiO) and 24.4% by weight tungsten components (as WO3) on a support of 20% LZ-10 and 80% gamma alumina.

Each of the foregoing catalysts was then activity tested according to the following method. A preheated light Arabian vacuum gas oil having the chemical and physical properties shown in Table II was passed on a once-through basis through an isothermal reactor containing 140 ml of catalyst particles uniformly mixed with 160 ml of 10 to 20 mesh quartz. Operat¬ ing conditions were as follows: 1.0 LHSV, 2000 psig (135 at .), a once-through hydrogen flow of 10,000 scf/bbl (1781 cc/ l) , and a run length of approximately 10 days. The temperature of the reactor was adjusted to provide a

60 volume percent conversion to products boiling at 700° F. (371° C.) or less. The results of the activity testing are reported in Table III.

TABLE II

PROPERTIES ^' OF LIGHT ARABIAN VACUUM GAS OIL

Gravity, °API 22.3 Pour Point, °F. (°C. ) 100.0 (38)

Distillation, °F. (°C) , D-1160 Sulfur, XRF, wt. % 2.37

IBP/5 693/760 ( 367/404 Nitrogen, KJEL,wt. % 0.079

10/20 777/799 ( 414/426 Hydrogen, wt.% 12-20 Chlorine, pern <1.0

30/40 815/832 ( 435/444

Carbon Residue,D-189,wt-% 0.14

50/60 850/870 ( 454/465

Viscosity, SSU at 100° F. 319.0

70/80 894/920 ( 479/493 (38° C.)

90/95 958/979 ( 514/526 Viscosity,SSU at 210° F. 51.1

(99° C.)

EP/%Rec. 1053/99.0( 567/99.0 Specific Gravity 0.9200

TABLE III

Catalyst Activity Selectivity ^• Stability

No. Description Reactor Temp, to Vol.% Conv.to of Support Provide 60% Conv. 300°-700°F.Product °F/day

(149°-371°C.) (°C/day)

10% LZ-10 and 772° F. 83.5 0.68 90% Garrma Alumina (411° C. ) (0.38)

10% LZ-10 and 750° F. 83.5 -0.72 90% Siθ2-Al ₂ θ3 in (399° C. ) (-0.40) Gaπma Alumina Matrix

5% LZ-10 and 776° F. 87.4 0.09 90% Siθ2-Al ₂ θ3 in (413° C. ) (0.05) Gamra Alumina Matrix

20% LZ-10 and 750° F. 75.2 0.39

80% G≤rrrra Alumina (399° C- ) (0.22)

1- Activity data arethose obtained on tenth-day of run. 2. Selectivity data are an average of data obtained over 10 days andarecalculated as the volume of 300°-700° F. (149°-371° C.) components to the total volume of cαπoDnents boiling at or fcelσw 700° F. (371° C.) .

3. Stability da-ta were calculated using the reactor terperature required to produce a 60% conversion on the 2nd and 10th caysof the run.

The data in Table III reveal that in comparison to the two hydrocracking catalysts having supports consisting of LZ-10 and gamma alumina, the catalysts of the invention are far superior in terms of overall activity, selectivity, and stability. A comparison of Catalyst Nos. 1 and 2 shows that, for the same percentage of LZ-10 in the support, Catalyst No. 2 prepared in accordance with the invention was 22° F. (12.2 °C) more active and much more stable than Catalyst No. 1. In addition, Catalyst No. 2 proved to be as selective for producing midbarrel products as Catalyst No. 1. Comparing Catalysts Nos. 2 and 4 and Catalysts 3 and 1 shows that the catalysts of the invention are as active, but substantially more stable and selective, than their LZ-10-alumina comparisons containing twice as much zeolite.

Example II

A second experiment was performed under the fun condi¬ tions of Example I to demonstrate the improved performance attainable with the catalysts of the invention in comparison to the catalysts described in U.S. Patent No. 4; 097,365. The catalysts utilized in the experiment were prepared as follows: Catalyst No. 5

A catalyst support was prepared in the same manner as described in Example 3 of U.S. Patent No. 4,097,365 except that 54 parts of the silica-alumina graft copolymer were mixed with 46 parts of the hydrous alumina gel. The support (in the size and shape as Catalyst No. 1) was calcined and impregnated with a nickel nitrate-ammonium metatungstate solution as in the preparation of Catalyst No. 1, and then dried and calcined in the same way. The final catalyst contained 4.1 wt.% nickel components (as NiO) and 24.4 wt.% tungsten components (as WO3) supported on a base consist¬ ing essentially of a dispersion of 75/25 silica-alumina in an alumina matrix, the base having an overall silica con¬ tent of 40% and an overall alumina content of 60%.

Catalvst No. 6

This catalyst was prepared in the same manner as Catalyst No. 5 except that LZ-10 in the ammonium form and peptized alumina binder were incorporated into the support such that, after calcination, LZ-10 in the hydrogen form comprised 10 percent by weight of the support and the binder comprised 20 percent by weight of the support.

The results obtained from testing Catalysts Nos. 5 and 6 for activity, selectivity, and stability are reported in Table IV.

TABLE IV a a 2 ^

Catalyst Activity Selectivity Stability"

No. Description Reactor Temp- to Vol. % Conv. to of Support Provide 60% Conv. 300°-700°F(149-371°C) °F/day Product (°C/day)

Dispersinn of Siθ2/ l2θ3 in Gaitma Alumina 773 °F 88.7 0.23 Matrix (412 °C) (0.13)

10% LZ-10. and 90% Dispersion of Siθ2~ l2θ3 in 753 °F 87.4 0.05 Gamπa Alumina (401 °C) (0.03)

1. Activity data are those obtained on tenth day of run.

2- Selectivity data are an average of data obtained over 10 days and are calculated as the volume of 300°-700° F. (149-371° C.) components to the total volume of components boiling at or below 700° F. (371°C).

3. Stability data were calculated using the reactor temperatures required to produce a 60% conversion on the 2nd and 10th days of the run.

As is self-evident from the data n Table IV, the catalyst of the invention, Catalyst No. 6, proved far super¬ ior to a catalyst similar to that described in Example 3 of U.S. Patent 4,097,365. Catalyst No. 6 provides substan¬ tially more activity and stability than Catalyst No. 5 with no significant loss in selectivity.

Example III

A third comparison experiment was run to determine the activity of two catalysts of the invention comprising nickel and molybdenum components on supports comprising LZ-10 and a dispersion of silica-alumina in a gamma alumina matrix versus a catalyst comprising nickel and molybdenum components on a support comprising LZ-10 and alumina but containing no dispersion. The catalysts were prepared as follows: Catalyst No. 7

Sixty grams of gamma alumina powder were comulled with. 120 gm LZ-10 in the ammonia form, 20 gm peptized alumina, 75 gm ammonium heptamolybdate ( (NH4) 5M07O24*4H ₂ 0) , and 85 gm nickel nitrate hexahydrate. The mulled mixture was extruded through a die similar to that used in preparing Catalyst No. 1, cut into 1/4-1/2 inch (0.64 to 1.27 cm.) lengths, and calcined in air at 900° F. (482° C) . The resulting cata¬ lyst contained 7.7 wt.% nickel components (as NiO), 21.9 wt.% molybdenum components (as M0O3) , about 43 wt.% LZ-10, about 21 wt.% gamma alumina, and the remainder (about 7 wt.%) peptized alumina. Catalyst No. 8

This catalyst was prepared in the same fashion as was Catalyst No. 7 except that, in place of the gamma alumina, 60 gm of a powdered dispersion of 75/25 silica-alumina in a gamma alumina matrix was used. The dispersion was pre¬ pared by spray drying a mixture comprising 33 parts by weight silica-alumina graft copolymer with 67 parts by weight of hydrous alumina gel. The final catalyst contained 7.4 wt.% nickel components (as NiO) , 21.5' wt.% molybdenum components (as M0O3) , ^a k°u 43 wt.% LZ-10, about 7% of pep¬ tized alumina, and about 21% of the dispersion containing 25 wt.% silica and 75 wt.% alumina overall. Catalyst No. 9 This catalyst was prepared in the same manner as

Catalyst No. 8 except that the dispersion was prepared by mixing 54 parts by weight of 75/25 silica-alumina graft

copolymer with 46 parts by weight of hydrous alumina gel. The final catalyst was of the same composition as Catalyst No. 8 except for the overall silica and alumina contents of the dispersion, which were 40% and 60% by weight, respectively.

The foregoing catalysts were subjected to the 10-day activity tests described in Example I, and the results are shown in Table V. As shown, the results prove the superior¬ ity of the catalysts of the invention (i.e., Catalysts Nos. 8 and 9) in all categories. In addition, the data show the improvement obtained when the silica contents of the catalysts of the invention are increased.

TABLE V

Catalyst Activity 3

Selectiviirv Stability ^" No. Description Reactor Temp. o Vol.% Conv. to of Support Provide 60% Conv. 300°-700°F. (149°-371°C.) °F./day

Product (°C-/day)

LZ-10 and 745° F. 74.8 1-43 Gaπrra Alumina (396°- C. (0.79)

LZ-10 and Si0 ₂ -Al θ3 in Gamma umina Matrix (25% Siθ2 743° F. 79.4 0.17 Overall) (395° C.) (0.09)

LZ-10 and Siθ2- l ₂ θ3 in Gaπma Alumina Matrix (40% Siθ2 733° F. 79.5 0.88 Overall) (389° C.) (0.49)

1. Activity data are those obt i ed on tenth day of run.

2. Selectivity data are an average of data obtai ed over 10 days and are calculated as the volume of 300°-700° F. (149°-371° C.) components to the total volume of cαrponents toiling at or below 700° F. (371°C.) . 3. Stability data were calculated using the reactor tempera¬ tures required to produce a 60% conversion cn the 2nd and 10th days of the run.

Example IV

A fourth experiment was conducted to compare the cat¬ alytic properties of a catalyst of the invention incorpo¬ rating a stabilized Y zeolite with the catalytic properties of a similar catalyst containing stabilized Y zeolite but containing no dispersion of silica-alumina in an alumina matrix. The two catalysts were prepared as follows: Catalyst No. 10

A mixture of 40 gm stabilized Y zeolite (prepared in accordance with the method described in U.S. Patent No.

3,929,672 for Catalyst A in Example 16 but without adding palladium) , 40 gm peptized alumina binder, and 120 gm of dispersion of the kind described for Catalyst No. 9 were comulled with a 380 ml aqueous solution containing 78 gm ammonium heptamolybdate tetrahydrate, 29.1 gm phosphoric acid (85% H3PO4) , and 85 gm nickel nitrate hexahydrate. The resulting material was extruded in the same manner as Catalyst No. 1, cut into particles of 1/4-1/2 inch (0.64 to 1.27 cm.) length, and calcined in air at 900° F. (482° C). The final catalyst contained about 6 wt.% nickel components (as NiO) j about 19 wt.% molybdenum components (as M0O3), and about 6 wt.% phosphorus components (as P ₂ 0,-) . Catalyst No. 11

This catalyst was prepared in a manner similar to that of Catalyst No. 10 with the major difference being (1) that the comulled mixture was extruded through a die having cir¬ cular openings therein of about 1/16 inch (0.16 cm.) dia¬ meter and (2) the comulled mixture contained 120 gm of powdered gamma alumina instead of the dispersion. The resulting catalyst had the same percentage composition of nickel, molybdenum, and phosphorus components as Catalyst No. 10.

The foregoing catalysts were then tested in a manner similar to that described in Example I except that Catalyst No. 10 was run for 13.6 days and Catalyst No. 11 for 8 days. The data obtained are presented in Table VI.

IS

TABLE VI

Catalyst Activity Selectivity Stability

No . Description Reactor Tsi£>.To Vol. % Conv. to °F/Day of Support Provide 60% Conv. 300°-700° F. (°C/Day)

(149°-371° C.) Product

10 Stabilized Y 1.1 for days 3.2 plus Si0 ₂ - to 10 AI2O3 in Gairma 733° F. 70.0 (0.61 for days 3.2 .Alumina Matrix (390° C. to 10)

0 for days 10.9 to 13.6

11 Stabilized Y plus Garrma 739° F. 73.0 0.58 for days 2.8 umina (393° C.) to 8.1 (0.32 for days 2.8 to 8.1)

Activity as reported for Catalyst No. 10 is a corrected value obtained from data determined for the 10th day of the run, and the activity data reported for Catalyst No. 11 is extrapolated from data derived on the eighth day oϊ

2. Selectivity data are the average of data obtained during the first 10 days with Catalyst No. 10 and the 8 days of run with Catalyst No. 11.

3. Stability data were calculated using the reactor tempera¬ tures required to produce a 60% conversion on the days specified in the Table.

The results in Table VI again show the overall superior- ity of the catalyst of the invention (Catalyst No . 10) with respect to activity, selectivity, and stability . The 6° F . (3 . 3 ° C. ) differential in activity between the catalyst of the invention and the comparison catalyst represents about a 20% improvement in activity. Especially significant is the fact that after 10. 9 days , Catalyst No . 10 showed no signs of deactivation , and thus the high activity indicated by the 733 ° F . ( 389° C . ) result could be expected to be maintained .

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Example V

Catalyst No. 12 was prepared in the same manner as

Catalyst No. 9 except that LZ-20 rather than LZ-10 was utilized. (LZ-20 is a crystalline aluminosilicate zeolite, available from Union Carbide, Linde Division, having a unit cell size, a water sorption capacity, a surface area, and an ion exchange capacity somewhat higher than that of LZ-10.)

The catalyst was tested in the same manner as described in Example I except that the run length was 8.5 days rather than 10 days. The results of the experiment were as follows: Activity: 733° F. (390° C.) (the operating temperature on the last day of run) , Selectivity: 67.0%

(as the average percentage conversion to middle distillates during the run), and Stability: 1.94° F/day (1.08° C/day) as calculated between 2.1 days and the end of run and

1.86° F/day (1.03° C/day) between 5.3 days and end of the run. A comparison of these data with those of Catalyst

No. 9 in Example III indicate that better results are obtained with LZ-10 in the catalyst support of the invention than with LZ-20.

Example VI

Catalyst No. 13 was prepared by mulling a mixture con¬ sisting essentially of 140 gm of a dispersion of silica- alumina in an alumina matrix as was used to prepare Catalyst No. 5, 20 gm LZ-10 in ammonia form (i.e., as in Example I), and 40 gm peptized alumina with 380 ml of an aqueous solu¬ tion containing 78 gm ammonium heptamolybdate tetrahydrate, 29.1 gm phosphoric acid (85% H3PO4), and 85 gm nickel nitrate hexahydrate. The mulled mixture was wet sufficient¬ ly to form a paste and extruded through a die similar to that described in Example I. The extrudate was cut into 1/4-1/2 inch (0.64 to 1.27 cm.) particles in length, dried, and calcined at 900° F. (482° C). The finished catalyst contained 7.6 wt.% nickel components (as NiO) , 21.2 wt.% molybdenum components (as M0O3) , and 7.1 wt.% phosphorus components (as P2O5) •

The foregoing catalyst was tested for its catalytic properties in the same manner as described in Example I, and the results were as follows: Activity: 750° F. (399° C. ) on the tenth day of run, Selectivity: 85.6 as the average over the ten days of operation, and Stability: 0.85° F./day (0.47° C/day) from days 2 through 10 and 0.11° F./day (0.06° C/day) from days 5.8 through 10. These results indicate the high activity, selectivity, and stability of this embodiment of the catalyst of the invention.

Example VII

During the runs performed on Catalyst No. 6 in Example II and Catalyst No. 10 in Example IV, samples of the product oils were obtained and analyzed for sulfur content by X-ray fluorescence analysis and nitrogen content by coulometric analysis. As shown by the data in Table II, the sulfur and nitrogen contents of the feedstock were 2.37 wt.% and 0.079 wt.%, respectively. In Table VII are reported the results of the analyses performed on the samples of product oil obtained in the experiments described in Examples II and IV. The data in. Table VII indicate that Catalysts Nos. 6 and 10 had substantial activity for hydrodenitro¬ genation- and hydrodesulfurization.

TABLE VII

Catalyst Tsro.°F. Days into Run When Sulfur in Nitrogen in

(°C.) Sample Taken Product, ptrw Product, p rw

N . 6 750 10 6 - (399)

No- 10 730 10 93 2.2 (388)

Nb. 10 734 13 62 1.3 (390)

Example VIII

Zeolite LZ-10 is believed to be prepared by high tem¬ perature, steam calcining the hydrothermally stable and ammonia-stable Zeolite Y compositions described in U.S. Patent No. 3,929,672, herein incorporated by reference. One specific method by which LZ-10 may be prepared is as follows:

A sample of air-dried ammonium exchanged Zeolite Y having a composition exclusive of water of hydration: 0.156 Na ₂ 0 : 0.849 (NH4) ₂ 0 : Al ₂ 0 ₃ : 5.13 Si0 ₂ is tableted into 1/2 inch (1.27 cm) diameter slugs and charged to a Vycor tube provided with external heating mean and having a 24 inch (61 cm.) length and a 2.5 inch (6.35 cm.) diameter. .The temperature of the charge is first raised to 600° C. in about 25 minutes and then held at this temperature for one hour. During this 1.25 hour period, a pure steam atmosphere at 14.7 psia (1 atin.) generated from demineralized water is passed upwardly through the charge at a rate of 0.1 to 0.5 lbs/hr (45.4 ^" to 227 gm/hr) . Ammonia gas generated during the heating deammoniation of the zeolite is passed from the system continuously. At the termination of the heating period, the steam flow is stopped and the temperature of the charge is lowered to ambient room temperature over a period of five minutes. The charge is removed from the Vycor tube, and the sodium cation content of the steam material is reduced to about 0.25 weight percent (as Na^O) by ion exchange using an aqueous solution of 30 weight percent ammonium chloride at reflux. The low sodium material thus prepared is recharged to the Vycor tube and again steamed, this time using pure steam at 14.7 psia (1 at .) and a temperature of 800° C. for 4 hours. The product is then cooled to ambient temperature and has the following typical characteristics: Surface

2

Area = 530 m /gm, A sorptive Capacity of water at 4.6 mm partial pressure and 25° C. = 4.6 weight percent, and an ion exchange capacity equal to 4% of that of a sodium Y zeolite having a comparable Si0 ₂ :Al ₂ θ3 ratio. (The *

comparable sodium Y zeolite to which LZ-10 zeolite is compared in the specification and claims herein is a sodium Y zeolite having essentially the same silica to alumina ratio as LZ-10 and having a sodium to aluminum content such that the ratio of Na ₂ 0 Al2θ3 is equal to 1.0).

Example IX

In this Example, the most preferred embodiment of the invention will be illustrated.

A gas oil feedstock, such as that shown in Table II, is passed through a reactor vessel of suitable industrial size and therein contacted at temperatures in the range of 700° to 750° F. (371° to 399° C) and at a pressure of about 2000 psig (135 atm. ) with a sulfided catalyst consisting essentially of about 5.0% by weight nickel components, cal- culated as NiO, and 25.0% by weight tungsten components, calculated as WO3, on a support consisting essentially of 40% LZ-10 zeolite in the hydrogen form and the balance a dispersion of a 75/25 silica-alumina dispersed in alumina, with the dispersion consisting of 44 parts silica-alumina and 56 parts alumina. Other conditions employed in the reactor vessel are: 5.0 LHSV space velocity and a hydrogen recycle rate of 5000 SCF/bbl ( 890.56 cc/ml) as measured at 60° F. (15.6° C) .

When operating in the foregoing manner, the overall activity, selectivity, and stability of the catalyst proves highly useful for the production of midbarrel products.

Industrial Applicability

Although it should be more than clear from the foregoing how the invention may be utilized in industry, one may briefly summarize by stating that the invention will find use in the petroleum refining industry, and more particular¬ ly in those processes employed in the petroleum refining industry that require catalysts. Catalysts prepared in accordance with the invention are most usefully employed without hydrogenation components in such processes as

catalytic cracking, catalytic isomerization, catalytic alkylation, and catalytic transalkylation. The catalysts of the invention are most usefully employed with one or more hydrogenation components when catalytic hydrocracking, catalytic hydrodenitrogenation, or catalytic hydrodesulfur¬ ization is required. The best contemplated use of the catalyst of the invention is for hydrocracking of gas oils and the like to produce midbarrel products boiling in the 300° to 700° F. (149° to 371° C.) range, and for such hydro- cracking, the most preferred catalyst comprises sulfided nickel and tungsten components on a support consisting essentially of LZ-10 zeolite in the hydrogen form and a dispersion of silica-alumina in gamma alumina.

While particular embodiments of the invention have been described, it will be understood, of course, that the inven¬ tion is not limited thereto since many obvious modifications can be made, and it is intended to include within this definition any such modifications as will fall within the scope of the appended claims. Having now described the invention, I claim: