软模板剂添加时间对SAPO-34分子筛的合成及MTO催化性能的影响  

Effect of adding time of soft template on synthesis of SAPO-34 molecular sieve and catalytic performance for MTO reaction

作　　者：李渊[1,2] 杨晨芳 LI Yuan;YANG Chen-fang(State Key Laboratory of Separation Membranes and Membrane Processes,Tiangong University,Tianjin 300387,China;School of Chemical Engineering and Technology,Tiangong University,Tianjin 300387,China)

机构地区：[1]天津工业大学省部共建分离膜与膜过程国家重点实验室,天津300387 [2]天津工业大学化学工程与技术学院,天津300387

出　　处：《天津工业大学学报》2022年第5期33-39,共7页Journal of Tiangong University

基　　金：国家自然科学基金资助项目(91745116)。

摘　　要：为合成更高性能的多级孔SAPO-34分子筛催化剂,使用四乙基氢氧化铵(TEAOH)和三乙胺(TEA)为混合模板剂,以聚乙二醇(PEG1500)为软模板剂,采用水热合成法合成多级孔SAPO-34分子筛催化剂。考察软模板剂的添加时间对多级孔SAPO-34分子筛合成的影响;采用XRD、SEM、FT-IR、NH3-TPD、XRF和BET等多种手段对样品进行表征,并使用固定床反应器对其MTO催化性能进行评价。结果表明:聚乙二醇作为介孔导向剂和结晶抑制剂,不仅可以在微孔结构中引入介孔,还可以起到抑制晶体结晶的作用;不同时间加入软模板剂对分子筛晶体的成核和生长产生不同结果,晶化4 h和22 h时添加软模板剂得到的产品形貌规整且不存在无定形颗粒,晶化8 h和14 h时添加软模板剂得到的产品晶体存在缺陷且有无定形颗粒存在;改变软模板剂添加时间,对分子筛的酸性会产生不同影响,晶化4 h时添加PEG1500得到的样品具有最优的催化效果,表现出最长的催化寿命(180 min)以及最高的双烯选择性(91.86%)。In order to synthesize SAPO-34 molecular sieve with better catalytic performance,using tetraethyl ammonium hydroxide(TEAOH)and TEA as mixed template and polyethylene glycol(PEG1500)as the soft template,hierarchical SAPO-34 molecular sieve catalyst was synthesized by hydrothermal method.The effect of changing the addition time of soft template on the synthesis of hierarchical SAPO-34 molecular sieve was investigated.The synthesized samples were characterized by XRD,SEM,FT-IR,NH3-TPD,XRF,BET and other methods,and its catalytic performance for methanol to olefin(MTO)reaction was evaluated by the fixed bed reactor.The results show that as a mesoporous directing agent and crystallization inhibitor,polyethylene glycol can not only introduce mesoporous into the microporous structure,but also inhibit crystal crystallization;the addition of soft template at different times has different effects on the nucleation and growth of molecular sieve crystals,the products obtained by adding soft template at the crystallization time of 4 h and 22 h have regular morphology and no amorphous particles,but the products obtained by adding soft template at the crystallization time of 8 h and 14 h have defects and amorphous particles;changing the addition time of soft template will have different effects on the acidity of molecular sieve,the sample obtained by adding PEG1500 at 4 h has the best catalytic effect,which shows the longest catalytic life(180 min)and the highest diene selectivity(91.86%).

关 键 词：软模板剂 多级孔 分子筛 结晶 酸性 甲醇制烯烃(MTO) 

分 类 号：TQ426[化学工程]