Selective Crystallization of AlPO4-41 Molecular Sieve in the Presence of Diethylamine

Abstract

A promising method providing the practical implementation of synthesis of AlPO4-41 alumophosphate molecular sieve with high phase purity using boehmite, phosphoric acid, and diethylamine as the template has been proposed. It has been shown that the mixing of the precursors at room temperature leads to the formation of a gel consisting of diethylamine phosphate, an amorphous aluminophosphate, and undissolved boehmite. It has been found that the introduction of the stage of gel aging at 90°C leads to the dominant formation of an amorphous aluminophosphate, the subsequent crystallization of which ensures the formation of high phase purity AlPO4-41 having cubic morphology of crystals with a size of 0.5–1 μm, a BET specific surface area S of 210 m2/g, and a micropore volume of 0.08 cm3/g.