Effect of synthesis conditions on the crystallinity and catalytic performances of SAPO-11 molecular sieves

A series of SAPO-11 molecular sieves were synthesized hydrothermally by varying the synthesis conditions, and were characterized by X-ray diffraction (XRD). The effects of synthesis conditions on the catalytic performances of SAPO-11 were also investigated. The results indicated that synthesis conditions had strong influence on the crystallinity and catalytic performances of SAPO-11. SAPO-11 molecular sieve was synthesized with di-n-propylamine (DPA) template at n(DPA):n(Al2O3) = 1.5, n(SiO2):n(Al2O3) = 0.2, crystallization time of 24 h and crystallization temperature of 170 °C, which was beneficial to the methylation of naphthalene with methanol. The deactivation behavior of SAPO-11 molecular sieve for the methylation of naphthalene with methanol was investigated. The results showed that a large number of water were generated in the methylation of naphthalene with methanol, which led to the structure collapse by the dealumination of high temperature stream, thus leading to the deactivation of molecular sieves.