Evaluation of surfactant templates for one-pot hydrothermal synthesis of hierarchical SAPO-5

Abstract Hierarchical SAPO-5 molecular sieves were synthesized with three different mesopore structure directing agents (meso-SDAs) (cetyltrimethyl-ammonium bromide (CTAB), myristyltrimethyl-ammonium bromide (MTMAB) and [3-(trimethoxysilyl) propyl] dimethyloctadecylammonium chloride (TPOAC)) based on a soft-template hydrothermal synthesis procedure. To investigate the modified porosity of the hierarchical SAPO-5s, they were characterized thoroughly with the results being compared to the conventional microporous SAPO-5. Nitrogen sorption measurements revealed considerable hysteresis loops for the hierarchical SAPO-5s as well as larger mesopore volumes (≥0.15 cm3 g-1) compared to the conventional SAPO-5 (0.05 cm3 g-1). The relative number of acid sites were calculated from FTIR adsorption data and were in the order of C-SAPO-5>H-CTAB > H-MTMAB > H-TPOAC. The hierarchical SAPO-5s had a significantly increased lifetime (>150 h) in the methanol to hydrocarbons (MTH) model reaction compared to the conventional SAPO-5 (