表面活性剂对SAPO-34晶体形貌的调控研究

Study on the control of SAPO-34 crystal morphology by the surfactant

分别以拟薄水铝石为铝源,磷酸为磷源,硅溶胶为硅源,三乙胺和四乙基氢氧化铵为模板剂,在反应体系中添加十八烷基三甲基溴化铵(STAB)合成板层状小晶粒SAPO-34分子筛。通过XRD、SEM、FT-IR、NH_3-TPD和N_2吸附-脱附等手段对样品进行表征。并且考察了样品在甲醇制烯烃(MTO)反应中的催化性能。结果表明,由于STAB长链分子的存在,在反应中形成了特定的有机序列,可以使分子筛样品的粒径变小,厚度变薄,强酸量略微增加,对比与传统方法做出的分子筛样品,具有更高的催化寿命和双烯(乙烯+丙烯)选择性。

The layered and small crystals of SAPO-34 molecular sieve were synthesized by adding a certain amount of octadecyltrimethylammonium bromide（STAB）and using pseudoboehmite as aluminum source,phosphoric acid as phosphorus source,silica sol as silicon source,and triethylamine and tetraethylammonium hydroxide as templates.The samples were characterized by XRD,SEM,FT-IR,NH_3-TPD and BET.The catalytic performances of these samples for converting methanol to olefins（MTO）were also evaluated.Results show that,due to the presence of STAB,a specific organic sequence is formed in the reaction and therefore the particle size becomes smaller and thinner and the content of strong acid increases slightly.In contrast with the molecular sieve samples prepared by traditional methods,it has higher catalytic lifetime and selectivity to ethylene and propylene.