Effect of the Aging Temperature of Gel on the Synthesis and Properties of the Silicoaluminophosphate Molecular Sieve SAPO-11

摘要

The effect of the aging temperature of the starting silicoaluminophosphate gel on the crystallization of the SAPO-11 molecular sieve was studied. When pseudoboehmite was used as an aluminum source, a gel containing di-n-propylamine phosphate, undissolved pseudoboehmite, and amorphous silicoaluminophosphate were formed. An increase in the aging temperature of the gel from 25 to 90 degrees C led to an increase in the fraction of the amorphous phase in the latter. Crystallization of the silicoaluminophosphate gel aged at 90 degrees C allows crystallization of SAPO-11 of high phase purity and nearly 98% crystallinity. High activity and selectivity for linear dimers (86%) of SAPO-11 in the dimerization of alpha-methylstyrene was shown.