Fluoride-free synthesis of high-silica CHA-type aluminosilicates by seed-assisted aging treatment for starting gel.

High-silica CHA-type aluminosilicates (Si/Al molar ratio >100) were synthesized hydrothermally in the absence of fluoride media, where the seed-assisted aging treatment played an important role on the crystallization. These aluminosilicates showed a long catalytic lifetime with high selectivity toward lower olefins in the methanol-to-olefins reaction.