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采用草酸铌氨为改性剂,研究了担载不同铌含量的Nb/HZSM-5分子筛的表面酸性以及环己烯水合反应的催化活性和选择性。XRD和BET分析表明:Nb2O5在HZSM-5呈高度分散状态,适宜负载量时,改性Nb/HZSM-5分子筛保持较好的结构特征;Py-TPD分析表明:铌组元的引入,避免了脱羟基作用使沸石分子筛的酸性降低,增加了分子筛的骨架稳定性。结果表明,在Nb2O5负载量6%(质量分数,下同),450℃焙烧4 h的条件下,催化剂活性最高,环己烯转化率达到14.7%,环己醇选择性为99.7%。
Niobium oxalate was used as modifier to study the surface acidity and the catalytic activity and selectivity of cyclohexene hydration for Nb / HZSM-5 zeolites loaded with different niobium. The results of XRD and BET show that the Nb2O5 is highly dispersed in HZSM-5, and the modified Nb / HZSM-5 molecular sieve retains good structural characteristics under suitable loading. Py-TPD analysis shows that the introduction of niobium Dehydroxylation reduces the acidity of the zeolite and increases the framework stability of the zeolite. The results show that the catalyst has the highest activity under the conditions of 6wt% Nb2O5 loading and 450 ℃ calcination for 4 h. The conversion of cyclohexene reaches 14.7% and the selectivity to cyclohexanol is 99.7%.