Effect of templates on synthesis of SAPO-41 and their catalytic performance in n-octane hydroisomerization

摘要

Silicoaluminophosphate molecular sieve SAPO-41 was synthesized with di-n-propylamine (DPA) and a mixture of DPA and diethylamine (DEA) as templates. The effect of templates on synthesis of SAPO-41 and their catalytic performance was studied. The products were characterized by XRD, XRF, SEM, MAS NMR and IR. Compared with the single-template method, the double-template method needs lower amounts of template and tends to make pure SAPO-41 with smaller crystal size and stronger acidity. The MAS NMR spectroscopic study showed that both DPA and DEA were entrapped in the channels of SAPO-41 sample synthesized by the double-template method. The structure of SAPO-41 molecular sieve synthesized by the single-template method was changed after calcination, while the structure of the SAPO-41 molecular sieve synthesized by the double-template method was retained. The SAPO-41 sample synthesized by DPA + DEA exhibited higher conversion of n-octane but lower isomer selectivity as compared to the SAPO-41 sample synthesized by DPA.