硅源对ZSM-5分子筛合成和催化性能的影响

为了考察硅源对ZSM-5分子筛合成和催化性能的影响,分别采用白炭黑、硅胶、硅溶胶和单分散SiO₂为硅源合成ZSM-5分子筛，对合成的ZSM-5分子筛进行XRD、SEM、BET和NH₃-TPD表征，并以C₄烯烃为原料评价合成的ZSM-5分子筛的催化裂解性能。结果表明，以硅溶胶为硅源合成的ZSM-5分子筛具有较好的结晶度和催化活性。水热处理使分子筛酸量减少，孔容缩小，改善了分子筛的乙烯丙烯选择性。经600 ℃水热处理4 h的ZSM-5分子筛在常压、580 ℃和空速9 h^-1反应条件下，丁烯催化裂解为乙烯和丙烯平均转化率为90.2%，乙烯和丙烯总收率达61.1%。

Effects of silicon sources on synthesis and catalytic properties of ZSM-5 zeolites

ZSM-5 zeolites were synthesized by using fumed-silica,silica gel,silica sol and monodisperse silica as silicon sources,respectively. The influence of silicon sources on synthesis and catalytic properties of ZSM-5 zeolites was investigated. The as-synthesized zeolites were characterized by XRD,SEM,BET and NH3-TPD,and their catalytic performance was evaluated by cracking of butene. The results indicated that the zeolite prepared with silica sol as silicon source exhibited higher relative crystallinity and better catalytic performance than other three zeolites. The hydrothermal treatment made the acid amount and pore volume of ZSM-5 zeolites decrease,which was favorable to the improvement of the selectivity to ethene and propene. Under the reaction condition of atmospheric pressure,580 ℃ and WHSV 9 h-1,the conversion of butene was 90. 2% and the total yield of ethene and propene was 61. 1% over ZSM-5zeolite treated by stream at 600 ℃ for 4 h.