Synthesis of chabazite-containing molecular sieves and their use in the conversion of oxygenates to olefins

Abstract

A method is disclosed of synthesizing a crystalline material comprising a CHA framework type molecular sieve and having a composition involving the molar relationship:()XO:YO,wherein X is a trivalent element; Y is a tetravalent element; and n is from 0 to less than 0.01. The method comprises preparing a reaction mixture capable of forming said material, said mixture comprising a source of water, a source of an oxide of a tetravalent element Y and optionally a source of an oxide of a trivalent element X, wherein the reaction mixture is substantially free of fluoride ions added as HF; maintaining the reaction mixture under conditions sufficient to form crystals of the crystalline material; and than recovering the crystalline material. The reaction mixture comprises either a specific directing agent for directing the formation of a CHA framework type molecular sieve and/or a HO:YOmolar ratio of greater than 20. In one embodiment, the resultant crystalline material is free of stacking faults and/or any intergrown phase with an AEI framework type molecular sieve.