关键词: 磷酸硅铝, 分子筛, 模板剂, 二乙胺, 三乙胺, 合成

Abstract: Using various templates, triethylamine (TEA), diethylamine (DEA) and TEA+DEA, SAPO-34 molecular sieve was synthesized, respectively. The test results showed that pure SAPO-34 crystal phase (CHA) could not be formed when using TEA as template, only CHA/AEI intergrowth crystal was formed. When using DEA as template, pure CHA phase was obtained under narrow synthesis conditions. SAPO-34 with pure CHA structure could be easily synthesized when using TEA+DEA mixed template having a DEA/TEA ratio of over 1. The effects of templates on the physicochemical properties and catalytic performance of the obtained products were studied. It was found that with the increase of DEA proportion in the mixed template, the content of silicon in the obtained molecular sieve increased, the specific surface area and pore volume decreased, the crystal size increased, the number of active acid sites decreased and with acid strength weaken. When the obtained SAPO-34 molecular sieve samples were used as catalysts in the methanol-to-olefin (MTO) reaction, it was observed that with the increase of DEA proportion in the mixed template, the ethylene yield decreased, propylene yield increased, and the selectivity of C2=+C3= increased gradually.

Key words: silicoaluminophosphate, molecular sieve, template, diethylamine, triethylamine, synthesis