以两亲性单季铵盐分子为模板剂合成的多级孔SAPO-34分子筛  

Hierarchical SAPO-34 templated by amphiphilic single-quaternary-ammonium surfactants

作　　者：申学峰 丁佳佳 刘红星 SHEN Xue-Feng;DING Jia-Jia;LIU Hong-Xing(SINOPEC Shanghai Research Institute of Petrochemical Technology Co.,Ltd,Shanghai 201208,China;State Key Laboratory of Green Chemical Engineering and Industrial Catalysis,Shanghai 201208,China)

机构地区：[1]中石化(上海)石油化工研究院有限公司,上海201208 [2]绿色化工与工业催化国家重点实验室,上海201208

出　　处：《无机化学学报》2023年第11期2065-2073,共9页Chinese Journal of Inorganic Chemistry

基　　金：上海市优秀学术/技术带头人计划(No.20XD1433000);上海市青年科技英才扬帆计划资助(No.21YF1459600)资助。

摘　　要：设计合成两亲性的单季铵盐分子作为助结构导向剂,两亲性分子具有晶体生长抑制剂或者致孔剂作用,最终导向合成多级孔/小晶粒SAPO-34分子筛。助结构导向剂减少Si进入AlPO_(4)骨架,降低分子筛的强酸酸性。相较于传统的SAPO-34分子筛(CS),添加助结构导向剂合成的多级孔SAPO-34颗粒尺寸较小,介孔孔体积较高,强酸酸性较弱,其在甲醇制烯烃反应中的双烯(乙烯和丙烯)选择性提高约4%,催化剂的寿命延长一倍。The introduction of mesopores and downsizing of the crystals of SAPO-34 can enhance its diffusion efficiency,leading to high catalytic activity in methanol-to-olefin(MTO)reactions.Amphiphilic single-quaternaryammonium molecules with different lengths of carbon chains([N^(+)(CH_(2)CH_(3))3-CnH_(2n+1)][Br^(-)],Cn-1N(n=4,6,8))were designed and synthesized as co-structure directing agents.Due to the electrostatic interaction,amphiphilic molecules acted as crystal growth inhibitors or pore-forming agents,which resulted in the formation of hierarchical SAPO-34(HS)zeolite with a smaller crystal size.When the carbon chain length was four(C4-1N),the hierarchical SAPO-34 zeolite(HS-4)was synthesized with a smaller crystal size and without other crystal phases.SAPO-34 zeolites with high mesopore volume(HS-6 and HS-8)were synthesized with C6-1N and C8-1N as co-structure directing agents.Without adding a co-structure directing agent,conventional SAPO-34(CS)was synthesized.There were many tetrahedral particles in CS,which is the early morphology of the cubic particles.The results of the X-ray fluorescence spectrometer(XRF)and 29Si magic angle spinning nuclear magnetic resonance(^(29)Si MAS NMR)indicated that Cn-1N molecules restrain Si atoms from incorporating into the AlPO_(4)framework.The results of NH_(3)-temperature-programmed desorption(NH3-TPD)proved the strong acid gradually decreases in the order of CS>HS-8>HS-6>HS-4.The diffusion behaviors of methanol molecules in HS-4,HS-6,and HS-8 were better than in CS.HS-4 showed excellent catalytic performance in MTO reaction:the selectivity of ethylene(C_(2)H_(4))and propylene(C_(3)H_(6))(84.4%)has improved by about 4%compared to that of CS(80.5%),and the catalyst lifetime of HS-4 was about two times the lifetime of CS.HS-6 also exhibited high selectivity of C_(2)H_(4)and C_(3)H_(6)(83.5%),and its lifetime was almost the same as HS-4.HS-8 had a high mesopore volume,but the higher strong acidity promoted hydrogen transfer reactions,leading to alkanes,aromatics,and coke,so the lif

关 键 词：SAPO-34 两亲性分子 多级孔 甲醇制烯烃反应 

分 类 号：O611.4[理学—无机化学]