Molecular sieve composition

Abstract

The invention relates to a crystalline molecular sieve composition which is obtainable by crystallizing a pre-formed extrudate mixture in a reactor and, during crystallization, removing excess alkali metal hydroxide from the pre-formed extrudate. The pre-formed extrudate mixture comprises at least one source of ions of tetravalent element Y, at least one source of alkali metal hydroxide, water, optionally at least one seed crystal, and optionally at least one source of ions of trivalent element X. The reaction mixture has the following mole composition: Y:X2=10 to infinity; OH−:Y=0.001 to 2; and M+:Y=0.001 to 2; wherein M is an alkali metal. The amount of water in the mixture is at least sufficient to permit extrusion of said reaction mixture.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings in which:

FIG. 1 presents a diagrammatic cross sectional view of a chamber for crystallizing a molecular sieve synthesis mixture under vapor phase conditions according to one embodiment of the invention, and

FIG. 2 presents a diagrammatic cross sectional view of a chamber for crystallizing a molecular sieve synthesis mixture under vapor phase conditions to form a crystalline molecular sieve according to another embodiment of the invention.

Claims

1. A crystalline molecular sieve composition obtainable by a) crystallizing a pre-formed extrudate mixture in a reactor, the preformed extrudate mixture comprising at least one source of ions of tetravalent element Y, at least one source of alkali metal hydroxide, water, optionally at least one seed crystal, and optionally at least one source of ions of trivalent element X, said reaction mixture having the following mole composition: Y:X2=10 to infinityOH−:Y=0.001 to 2M+:Y=0.001 to 2wherein M is an alkali metal and the amount of water is at least sufficient to permit extrusion of said reaction mixture; andb) during crystallization, removing excess alkali metal hydroxide from the pre-formed extrudate.

2. A composition according to claim 1, characterized in that the source of ions of the tetravalent element Y binds the extrudate during crystallization to form a three-dimensional interconnecting crystallized structure.

3. A composition according to claim 1, characterized by the pre-formed extrudate comprising a structure directing agent R.

4. A composition according to claim 1, characterized by the reactor containing water and/or structure directing agent R.

5. A composition according to claim 1, characterized by the Y:X2 ratio being 50 to 5000.

6. A composition according to claim 1, characterized by the water:Y ratio being 0.5 to 5.

7. A composition according to claim 1, the OH−:Y ratio being 0.1 to 1.

8. A composition according to claim 1, characterized by the M+:Y ratio being 0.01 to 2.

9. A composition according to claim 1, characterized by the tetravalent element being silicon.

10. A composition according to claim 9, characterized by the source of ions of the tetravalent element comprising a source of silica.

11. A composition according to claim 1, characterized by the trivalent element being aluminum.

12. A composition according to claim 11, characterized by the source of ions of the trivalent element comprising a source of alumina.

13. A composition according to claim 1, characterized by the mixture comprising silica/alumina in a ratio of between 10 to 5000.

14. A composition according to claim 13, characterized by the mixture comprising SiO2/Al2O3 in a ratio of 10 to 500.

15. A composition according to claim 1, characterized by the mixture comprising OH/SiO2 in a ratio of 0.001 to 1, preferably 0.1 to 1.

16. A composition according to claim 1, characterized by the mixture comprising Na/SiO2 in a ratio of 0.001 to 2, preferably 0.01 to 2.

17. A composition according to claim 1, characterized by the mixture comprising H2O/SiO2 in a ratio of 1 to 20.

18. A composition according to claim 1, characterized by the seed concentration being from 0.1-40 wt % of the weight of the mixture.

19. A composition according to claim 1, characterized by the composition comprising a crush strength of at least 5.4 kg/cm (30 lb/inch), preferably at least 7.2 kg/cm (40 lb/inch) and more preferably at least 9.8 kg/cm (55 lb/inch).

20. A crystalline molecular sieve composition having a crush strength of at least 5.4 kg/cm (30 lb/inch).

21. A composition according to claim 20 having a crush strength of at least 18 kg/cm (39.7 lb/inch), preferably at least 9.8 kg/cm (55 lb/inch).

22. A composition according to claim 20, characterized by the composition comprising a surface area of at least 300 m2/g, preferably at least 400 m2/g.

23. A composition according to claim 20, characterized by the composition comprising a bulk density of less than 1 g/cc, preferably less than 0.75 g/cc, more preferably less than 0.5 g/cc.

24. A composition according to claim 20, characterized by the composition comprising an intrusion volume of greater than 1 ml/g, preferably greater than 1.5 ml/g.

25. A composition according to claim 20, characterized by the molecular sieve being a sieve of the MCM-22 family.

26. A composition according to claim 25, characterized by the MCM-22 family sieves comprising MCM-22, MCM-49 or MCM-56.

27. A composition according to claim 20, characterized by the composition being a dual molecular sieve.

28. A composition according to claim 27, characterized by the molecular sieve comprising zeolite beta, zeolite Y, Mordenite, ZSM-5 or ZSM-12.

29. A composition according to claim 20, characterized by the composition being free from a binder.

30. A catalyst or catalyst additive comprising the composition according to claim 1 or 20.

31. A post treated catalyst according to claim 30, the catalyst being post-treated by water washing, and/or acid solution washing, and/or metal oxide surface modification, and/or calcining and/or combinations of the aforesaid treatments.

32. A process for converting hydrocarbons comprising the step of contacting a hydrocarbon feedstock under conversion conditions with a catalyst or catalyst additive according to claim 30.