The effects of two pseudo-boehmites on the synthesis of molecular sieve SAPO-41

A unidimensional medium-pore molecular sieve SAPO-41 was hydrothermally synthesized by using pseudo-boehmite as Al source, silica sol as Si source and di-n-propylamine (DPA) as template. The samples obtained were characterized by XRD and SEM. The pure phase SAPO-41 was obtained from the gels with n(SiO₂)/n(Al₂O₃) in range of 0.08-0.12, n(DPA)/n(Al₂O₃) in range of 2.8-4, pH in range of 7.5-8.5. The effects of two pseudo-boehmites on SAPO-41 crystallization were discussed. When the pseudo-boehmite with high purity and low pore volume was used, the product was crystallized directly to SAPO-41 with high crystallization, while the pseudo-boehmite with relative low purity and high pore volume was used, the product was crystallized to SAPO-11 and SAPO-41 simultaneously, then the SAPO-11 transformed to SAPO-41 during further crystallization time, resulting in the SAPO-41 with low crystallinity.