Method of preparing a molecular sieve and its use in the conversion of oxygenates to olefins
AssigneeExxonMobil Chemical Patents Inc.
InventorsMachteld M. Mertens, Chunshe Cao
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Abstract
A method of preparing a silicoaluminophosphate molecular sieve which comprises the steps of combining a source of silica, a source of phosphorous, a source of alumina and water to form a primary mixture; adding a structure directing agent to said mixture and optional seeds to form a synthesis mixture. The synthesis mixture is synthesized by heating the mixture to a crystallization temperature to form the sieve. The molar ratio of the structure directing agent relative to the source of alumina may vary between 1.3 and 1.9 and the ratio of water to the source of alumina may vary between 20 to 34.
Claims17
A silicoaluminophosphate molecular sieve crystallized from a synthesis mixture comprising a source of colloidal silica (SiO2), a source of phosphorus, a source of alumina (Al2O3), water (H2O), a structure directing agent (R) and optional seeds, wherein the molar ratio of structure directing agent relative to the source of alumina R/Al2O3 ranges from 1.3 to 1.9 and the ratio of water to the source of alumina H2O/Al2O3 ranges from 20 to 34, said sieve comprising a crystal size distribution such that the average crystal size as measured from SEM micrographs, is between 0.7 to 2.2μm.
A method of preparing a silicoaluminophosphate molecular sieve, comprising:
- (a) combining a source of silica (SiO2), a source of phosphorus, a source of alumina (Al2O3), and water (H2O) to form a primary mixture, wherein the source of silica is in the form of a colloidal silica source;
- (b) adding a structure directing agent (R) to said mixture and optionally seeds to form a synthesis mixture;
- followed by (c) heating said synthesis mixture to a crystallization temperature to form the molecular sieve;
- and
- wherein the molar ratio of structure directing agent relative to the source of alumina R/Al2O3 ranges from 1.3 to 1.9 and the molar ratio of water to the source of alumina H2O/Al2O3 ranges from 20 to 34.
Dependencies are inferred from the claim text.