Method of preparing a molecular sieve composition
A method of preparing a crystalline molecular sieve is provided, which method comprises (a) providing a reaction 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:X 2 =10 to infinity OH − :Y=0.001 to 2 M + :Y=0.001 to 2 wherein M is an alkali metal and the amount of water is at least sufficient to permit extrusion of said reaction mixture; (b) extruding said reaction mixture to form a pre-formed extrudate; and (c) crystallizing said pre-formed extrudate under vapor phase conditions in a reactor to form said crystalline molecular sieve whereby excess alkali metal hydroxide is removed from the pre-formed extrudate during crystallization. The crystalline molecular sieve product is useful as catalyst in hydrocarbon conversion processes.
1. A catalyst or catalyst additive comprising a crystalline molecular sieve prepared by the method comprising the steps of:
(a) providing a reaction 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:X 2 =10 to infinity
OH − :Y=0.001 to 2
M + :Y=0.001 to 2
wherein M is an alkali metal and the amount of water is at least sufficient to permit extrusion of said reaction mixture;
(b) extruding said reaction mixture to form a pre-formed extrudate; and
(c) crystallizing said pre-formed extrudate under vapor phase conditions in a reactor to form said crystalline molecular sieve whereby excess alkali metal hydroxide is removed from the pre-formed extrudate during crystallization.
2. The catalyst or catalyst additive according to claim 1 , characterized by the pre-formed extrudate comprising a structure directing agent R.
3. The catalyst or catalyst additive according to claim 1 , characterized by the reactor containing water and/or structure directing agent R.
4. The catalyst or catalyst additive according to claim 3 , characterized by the pre-formed extrudate being spaced from the water and/or structure directing agent in said reactor.
5. The catalyst or catalyst additive according to claim 1 , characterized by the pre-formed extrudate being disposed in the reactor in a position that is spaced from at least one inner perimeter wall of said reactor.
6. The catalyst or catalyst additive according to claim 5 , characterized by the reactor comprising a support for spacing the extruded mixture from the water and/or structure directing agent.
7. The catalyst or catalyst additive according to claim 1 , characterized by the pre-formed extrudate being provided on a support in the reactor, the support being adapted to allow removal of the alkali metal hydroxide during crystallization of the pre-formed extrudate.
8. The catalyst or catalyst additive according to claim 1 , characterized by the mixture being dried prior to performing step b).
9. The catalyst or catalyst additive according to claim 1 , characterized by the mixture being exposed to an autogenous pressure of 50 psig (345 kPa) to 500 psig (3450 kPa) and a temperature of 50° C. to 250° C. during crystallization.
10. The catalyst or catalyst additive according to claim 1 , characterized by the Y:X 2 ratio being 50 to 5000.
11. The catalyst or catalyst additive according to claim 1 , characterized by the H 2 O:Y ratio being 0.5 to 5.
12. The catalyst or catalyst additive according to claim 1 , the OH − :Y ratio being 0.1 to 1.
13. The catalyst or catalyst additive according to claim 1 , characterized by the M + :Y ratio being 0.01 to 2.
14. The catalyst or catalyst additive according to claim 1 , characterized by the mixture being suited to form crystals of molecular sieves of the MCM-22 family under the applied vapor phase crystallization conditions.
15. The catalyst or catalyst additive according to claim 14 , characterized by the MCM-22 family molecular sieves comprising MCM-22, MCM-49, MCM-56.
16. The catalyst or catalyst additive according to claim 1 , characterized by the pre-formed extrudate further comprising a synthesized molecular sieve to form a dual molecular sieve after crystallization.
17. The catalyst or catalyst additive according to claim 16 , characterized by the synthesized molecular sieve comprising zeolite beta, zeolite Y, Mordenite, ZSM-5 or ZSM-12.
18. The catalyst or catalyst additive according to claim 1 , characterized by the pre-formed extrudate being free from a binder.
19. The catalyst or catalyst additive according to claim 1 , characterized by the source of alkali metal hydroxide comprising a caustic agent, the caustic agent comprising a sodium hydroxide solution.
20. The catalyst or catalyst additive according to claim 1 , characterized by the tetravalent element comprising silicon.
21. The catalyst or catalyst additive according to claim 1 , characterized by the source of ions of the tetravalent element comprising a source of silica.
22. The catalyst or catalyst additive according to claim 1 , characterized by the trivalent element comprising aluminum.
23. The catalyst or catalyst additive according to claim 1 , characterized by the source of ions of the trivalent element comprising a source of alumina.
24. The catalyst or catalyst additive according to claim 1 , further comprising the step of water treating the crystallized extrudate and/or modifying the surface of the crystal to provide a metal oxide on the surface.
25. A process for converting hydrocarbons comprising the step of contacting a hydrocarbon feedstock under conversion conditions with the catalyst or catalyst additive of claim 1 .