铌改性HZSM-5分子筛催化环己烯水合反应研究

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%。

Catalytic Activity of Modified HZSM-5 on Hydration of Cyclohexene

A method of modify HZSM-5 by using niobium oxalate ammonium is introduced. We studied the surface acidity of Nb/HZSM-5 with different Nb content and the catalytic activity of cyclohexene hydration reaction. XRD and BET characterization results showed that： niobic acid had been highly dispersed, when Nb205 was added to HZSM-5 with suitable amount, the modified Nb/HZSM-5 showed a preservation of the zeolite structure ; Py-TPD showed that the introduce of the niobium avoiding the dehydroxylation of zeolite which led acid reduction, and also increased the framework stability of zeolite catalyst. Loading with 6% （wt%）Nb2O5, calcined at 450 ℃ for 4 h got the highest catalytic activity, which the conversion of cyclohexene was 14.7% and the selectivity of cyclohexanol was 99.7%.