US Patent 7578987 Synthesis of SAPO-34 with essentially pure CHA framework

A process for producing an ElAPO molecular sieve with essentially pure CHA framework having an average crystal size less than about 5 micrometers is disclosed. When El is silicon, the process allows for a broad range of silicon content, and produces a catalyst with a high selectivity for the conversion of methanol to olefins. The process includes making a crystalline metallo-aluminophosphate molecular sieve of the formula (ElxAlyPz)O2from a mixture comprising an aluminum source, a phosphorous source, water, an El source, a fluorine source and an organic template source wherein the molar ratio of the organic template source to phosphorous is less than about 0.5; crystallizing the molecular sieve at a temperature between 100 C and 250 C and calcining in air.