以三乙胺和四乙基氢氧化铵为混合模板剂,在反应体系中添加一定量氢氧化六甲双铵为辅助模板剂,成功合成出板层状SAPO-34分子筛,考察了添加辅助模板剂对SAPO-34分子筛合成过程的影响;采用XRD、SEM、FT-IR、XRF、NH3-TPD和低温N_2吸附-脱附等手段表征所合成样品,并评价了其在甲醇制烯烃(MTO)反应中的催化性能。结果表明,一定范围内,随着双头季铵碱添加量的增加,所合成的板层状SAPO-34分子筛晶粒粒径变小,强酸量变低;小晶粒板层状形貌的SAPO-34分子筛在MTO催化反应中表现出了更长的寿命、更短的诱导期,并能得到更高的(乙烯+丙烯)选择性。
The layered SAPO-34 molecular sieve was synthesized by adding a certain amount of hydroxide hexamethonium and with triethylamine and tetraethyl-ammonium hydroxide as template agent.The synthesized samples were characterized by XRD,SEM,FT-IR,XRF,NH_3-TPD,BET and the catalytic performances of these samples for methanol to olefins(MTO)reaction were evaluated.The influence of additive amount of hydroxide hexamethonium was studied.The results showed that the smaller layered crystals of SAPO-34 were obtained in certain range with the increase of hydroxide hexamethonium amount,which possessed a longer life expectancy and a shorter induction period in catalytic MTO reaction,and higher light olefins selectivity can be realized.