晶化时间对SAPO-34晶相结构及MTO催化性能的影响

Effect of Crystallization Time on Crystal Phase Structure and MTO Catalytic Performance of SAPO-34

以拟薄水铝石、硅溶胶和磷酸为原料,三乙胺和四乙基溴化铵为模板剂,改变晶化时间,通过水热法合成了一系列SAPO-34分子筛。利用XRD、SEM和NH3-TPD等技术对合成的SAPO-34分子筛晶相结构和物化性能进行分析表征。在固定床反应器上进行了MTO催化活性评价实验。结果表明,不同晶化时间下均合成了纯相的片层状SAPO-34分子筛。晶化时间越长,结晶度越高,片层状厚度随之增加,样品的酸中心数目越多。在反应温度为450℃、空速为2 h^-1、反应压力为0.2 MPa、晶化时间为72 h的条件下,合成SAPO-34分子筛的MTO反应单程寿命达到360 min,双烯收率可达86.8%。

A series of SAPO-34 molecular sieves with different crystallization time were synthesized by hydrothermal method using pseudo-boehmite,silica sol and phosphoric acid as raw materials,TEA&TEABr as template.The crystal structure and physicochemical properties of the synthesized SAPO-34 molecular sieve were characterized by XRD,SEM and NH3-TPD.The catalytic activity of MTO was evaluated in a fixed bed reactor.The results showed that pure phase lamellar SAPO-34 molecular sieves were synthesized under different crystallization time.The longer the crystallization time was,the higher the crystallinity was,the greater the lamellar thickness was,and the more the acid centers were.At 450℃,2 h^-1,0.2 MPa,crystallization time 72 h,the SAPO-34 molecular sieve had the best MTO catalytic activity with a single-pass lifetime 360 min and yield of diene 86.8%.