Hydrocracking catalyst

1. A middle distillate selective hydrocracking catalyst composition which comprises a metal hydrogenation component selected from the group of metals consisting of molybdenum, tungsten, cobalt, nickel and combinations of two or more thereof supported on a carrier comprising an amorphous binder component and from 2 to 80% by weight, based on the total weight of the carrier, a zeolite of the faujasite structure having a unit cell size in the range of from 24.14 to 24.38 Å, a bulk silica to alumina ratio (SAR) above about 12, a surface area of at least about 850 m 2 /g as measured by the BET method and ATSM D 4365-95 with nitrogen adsorption at a p/po value of 0.03, and a micropore volume of at least about 0.28 ml/g.

2. A composition as claimed in claim 1 , wherein the zeolite has a unit cell size in the range of from 24.24 to 24.38 Å.

3. A composition as claimed in claim 1 , wherein the zeolite has a SAR in the range of from about 20 to about 100.

4. A composition as claimed in claim 1 , wherein the zeolite has a surface area of at least about 890 m 2 /g.

5. A composition as claimed in claim 1 , wherein the zeolite has a micropore volume greater than 0.30 ml/g.

6. A composition as claimed in claim 1 , which further comprises a second zeolite.

7. A composition as claimed in claim 6 , which further comprises in the range of from 1 to 5% by weight of zeolite beta, basis total carrier.

8. A hydrocracking catalyst composition of any one of claims 1 , 2 , 3 , 4 , 5 , 6 , and 7 , wherein said zeolite is made by a process which comprises

a) hydrothermally treating a starting zeolite of the faujasite structure having a silica to alumina molar ratio in the range of from about 4.5 to about 6.5, and an alkali content of less than about 1.5% wt; at a temperature in the range of from 600° C. to 800° C. and at a partial pressure of steam in the range of from about 0.2 to about 1 atmosphere for a time effective to produce an intermediate zeolite having a unit cell size of from 24.30 to 24.45 Å;

b) contacting said intermediate zeolite with an acidified solution comprising an acid and an ammonium salt under conditions effective to produce said zeolite; and

c) recovering said zeolite.

9. A middle distillate selective hydrocracking catalyst composition as recited in claim 1 , wherein said unit cell size of said zeolite is in the range of from 24.24 to 24.38 Å and said bulk silica to alumina ratio is in the range of from 20 to 100.

10. A middle distillate selective hydrocracking catalyst composition as recited in claim 9 , wherein said metal hydrogenation component includes at least two hydrogenation components with a first hydrogenation component selected from the group consisting of molybdenum and tungsten, and a second hydrogenation component selected from the group consisting of nickel and cobalt.

11. A middle distillate selective hydrocracking catalyst composition as recited in claim 10 , further comprising: a second zeolite selected from the group consisting of zeolite beta, ZSM-5 and zeolite Y having a second zeolite unit cell size greater than 24.40 Å.

12. A middle distillate selective hydrocracking catalyst composition as recited in claim 11 , wherein said amorphous binder component is selected from the group consisting of alumina, silica, silica-alumina, and mixtures thereof.

13. A middle distillate selective hydrocracking catalyst composition as recited in claim 12 , wherein said zeolite is present in said composition in amount up to 90 weight percent and said second zeolite is present in said composition in an amount up to 20 weight percent, wherein said weight percents are based on the total sum weight of said amorphous binder component, said high surface area zeolite and said second zeolite; and wherein said metal hydrogenation component is present in said composition in the range of from 2 to 40 parts by weight (calculated as metal) per 100 parts by weight of the total composition.

14. A middle distillate selective hydrocracking catalyst composition as recited in claim 1 , wherein said unit cell size is in the range of from 24.30 to 24.36 Å.

15. A middle distillate selective hydrocracking catalyst composition as recited in claim 1 , wherein said unit cell size is in the range of from 24.30 to 24.35 Å.

16. A middle distillate selective hydrocracking catalyst composition as recited in claim 1 , wherein said zeolite has an alkali content of less than about 1% wt.

17. A process for the conversion of a hydrocarbonaceous feedstock into lower boiling materials, which comprises contacting the feedstock with hydrogen at elevated temperature and pressure in the presence of a hydrocracking catalyst composition which comprises a metal hydrogenation component selected from the group of metals consisting of molybdenum, tungsten, cobalt, nickel and combinations of two or more thereof supported on a carrier comprising an amorphous binder component and from 2 to 80% by weight, based on the total weight of the carrier, a zeolite of the faujasite structure having a unit cell size in the range of from 24.14 to 24.38 Å, a bulk silica to alumina ratio (SAR) above about 12, and a surface area of at least about 850 m 2 /g as measured by the BET method and ATSM D 4365-95 with nitrogen adsorption at a p/po value of 0.03, and a micropore volume of at least about 0.28 ml/g.

18. A process as claimed in claim 17 , which is carried out at a temperature in the range of from 250 to 500° C. and a total pressure in the range of from 3×10 6 to 3×10 7 Pa.

19. A composition comprising: a first zeolite of the faujasite structure having a first zeolite unit cell size in the range of from 24.24 to 24.38 Å; a bulk silica to alumina molar ratio in the range of from 20 to 100; and a surface area of at least 850 m 2 /g.

20. A composition as recited in claim 19 , further comprising: a metal hydrogenation component selected from the group consisting of nickel, cobalt, molybdenum, tungsten, platinum and palladium.

21. A composition as recited in claim 20 , further comprising: a second zeolite selected from the group consisting of zeolite beta, ZSM-5 and zeolite Y having a second zeolite unit cell size greater than 24.40 Å.

22. A composition as recited in claim 21 , further comprising: an amorphous binder component selected from the group consisting of alumina, silica, silica-alumina, and mixtures thereof.

23. A composition as recited in claim 22 , wherein said first zeolite is present in said composition in amount up to 90 weight percent and said second zeolite is present in said composition in an amount up to 20 weight percent, wherein said weight percents are based on the total sum weight of said amorphous binder component, said first zeolite and said second zeolite; and wherein said metal hydrogenation component is present in said composition in the range of from 2 to 40 parts by weight (calculated as metal) per 100 parts by weight of the total composition.

24. A composition as recited in claim 19 , wherein said first zeolite unit cell size is in the range of from 24.24 to 24.36.

25. A composition as recited in claim 19 , wherein said first zeolite unit cell size is in the range of from 24.30 to 24.35.

26. A composition as recited in claim 19 , wherein said first zeolite has a micropore volume of greater than about 0.28 m 2 /g and said first zeolite unit cell size is in the range of from 24.30 to 24.35, said bulk silica to alumina molar ratio is in the range of from 20 to 50, and said surface area is at least 910 m 3 /g.

27. A middle distillate selective hydrocracking process, comprising: providing a feedstock comprising hydrocarbons boiling in the range of from 330° C. to 650° C.; contacting said feedstock in the presence of hydrogen at an elevated temperature and an elevated pressure with a middle distillate selective hydrocracking catalyst composition as defined in any one of claims 1 , 2 , 3 , 4 , 5 , 6 , 7 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , and 16 ; and yielding a middle distillate product comprising middle distillate hydrocarbons boiling in the range of from 150° C. to 370° C., wherein said elevated temperature is in the range of from 250° C. to 500° C.; said elevated pressure is in the range of from 3×10 6 to 3×10 7 Pa; and said hydrogen is present in an amount such that the hydrogen partial pressure is in the range of from 4×10 6 to 2.5×10 7 Pa; and the space velocity is in the range of from 0.1 to 10 kg of said feedstock per liter of said middle distillate selective hydrocracking catalyst composition per hour (kg×l −1 ×hr −1 ).

28. A composition as recited in any one of claims 19 , 24 , and 25 , wherein said surface area is at least 875 m 2 /g.

29. A composition as recited in claim 19 , 24 , 25 and 28 , wherein said first zeolite has a first zeolite micropore volume greater than about 0.28 m 3 /g.

30. A composition as recited in claim 19 , 24 , 25 and 28 , wherein said bulk silica to alumina molar ratio is in the range of from 20 to 50.

31. A composition as recited in claim 19 , 24 , 25 and 28 , wherein said first zeolite is made by a process that comprises:

a) hydrothermally treating a starting zeolite of the faujasite structure having a silica to alumina molar ratio in the range of from about 4.5 to about 6.5, and an alkali content of less than about 1.5% wt; at a temperature in the range of from 600° C. to 800° C. and at a partial pressure of steam in the range of from about 0.2 to about 1 atmosphere for a time effective to produce an intermediate zeolite having a unit cell size of from 24.30 to 24.45 Å;

b) contacting said intermediate zeolite with an acidified solution comprising an acid and an ammonium salt under conditions effective to produce said first zeolite; and

c) recovering said first zeolite.