Chabazite-type molecular sieve, its synthesis and its use in the conversion of oxygenates to olefins
AssigneeExxonMobil Chemical Patents Inc.
InventorsMachteld M. Mertens, Guang Cao, Hailian Li, Anil S. Guram, Robert J. Saxton, Mark T. Muraoka, Jeffrey C. Yoder
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Abstract
The synthesis of a crystalline material, in particular a high silica zeolite, having a chabazite-type framework is aided by the addition to the synthesis mixture of seeds of an AEI framework-type material. The chabazite-type product has a relatively small crystal size and exhibits activity and selectivity in the conversion of methanol to lower olefins, especially ethylene and propylene.
Claims57
A method of synthesizing a crystalline material having a CHA framework-type, the method comprising:
- a) forming a reaction mixture capable of forming said crystalline material having a CRA framework-type, wherein the reaction mixture further comprises seeds of a crystalline material comprising an AEI framework-type;
- and
- b) recovering from said reaction mixture said crystalline material comprising a CHA framework-type.
A method of synthesizing a crystalline material having a CHA framework-type and having, in its calcined and anhydrous form, a composition involving the molar relationship:
- (n)X2O3:YO2,
- wherein X is a trivalent element;
- Y is a tetravalent element, and n is from 0 to less than 0.01, the method comprising:
- (a) preparing a reaction mixture capable of forming said crystalline material having a CHA framework-type, said reaction mixture comprising a source of water, a source of an oxide of the tetravalent element Y, optionally a source of an oxide of the trivalent element X, an organic directing agent for directing the formation of said crystalline material having a CHA framework-type and seeds of a crystalline material having a framework-type other than CHA,
- (b) maintaining said reaction mixture under conditions sufficient to form crystals of said crystalline material having a CHA framework-type;
- and
- (c) recovering said crystalline material from (b).
A crystalline material having a CHA framework type and having, in its calcined and anhydrous form, a composition involving the molar relationship:
- (n)X2O3:YO2,
- wherein X is a trivalent element, Y is a tetravalent element and n is from 0 to less than 0.01, and wherein the crystals of said material have an average diameter of from about 0.5 micron to 4 micron.
A crystalline material having a CHA framework type and having, in its caicined and anhydrous form, a composition involving the molar relationship:
- (n)X2O3:YO02,
- wherein X is a trivalent element, Y is a tetravalent element and ii is from 0 to less than 0.01, and wherein the crystals of said material are twinned.
Dependencies are inferred from the claim text.