钛钨改性HMS的合成及催化氧化苯甲醇合成苯甲醛

Catalytic Oxidation of Benzyl Alcohol to Benzyl Aldehyde with Ti/W-HMS

通过改变硅钛摩尔比和硅钨摩尔比合成了Ti-HMS和Ti/W-HMS型分子筛,并进行了NH3-TPD测试分析。结果表明,当n(Si)∶n(Ti)=30∶1、n(Si)∶n(W)=400∶1时,分子筛的酸量最大。利用上述不同HMS为催化剂,ω(H2O2)=30%的H2O2水溶液为氧化剂,在无有机溶剂及相转移催化剂条件下,氧化苯甲醇制备苯甲醛。结果表明,Ti/W-HMS可选择性氧化苯甲醇制备苯甲醛;催化剂的酸量和酸强度越大,越有利于提高催化活性和选择性。利用Ti(30)/W(400)-HMS为催化剂,当n(醇)∶n(H2O2)=1∶2、ω(催化剂)=4%、反应时间为5 h时,苯甲醇的转化率和苯甲醛的选择性分别为72.6%、96.9%。催化剂重复使用4次后,苯甲醇的转化率和苯甲醛的选择性分别为63.2%、89.1%。

Ti-HMS and Ti/W-HMS molecular sieves were synthesized by varying the ratio of n （Si）/n （Ti） and n（ Si）/n（ W）, and were used for the NH3-TPD analysis. The acidity of the molecular sieve is the largest when n （ Si ） ： n （ Ti ） = 30： 1, n （ Si ） ： n （W） = 400： 1. Different HMS were used for the oxidation of benzyl alcohol to benzyl aldehyde with 30% hydrogen peroxide solution as the oxidizing agent without any organic solvent and phase transfer catalyst. The results show that benzyl alcohol can be selectivity oxidized to benzyl aldehyde by Ti/W-HMS molecular sieves. The activity and selectivity of catalyst can be improved with increasing the acidity and acid strength. With Ti （30）/W （400） -HMS as catalyst, at n （alcohol） ： n （ hydrogen peroxide） = 1：2, to（catalyst） = 4%, and the reaction time 5 h, the conversion of benzyl alcohol and the selectivity of benzyl aldehyde reached to 72.6% and 96.9%, respectively. The conversion of benzyl alcohol and the selectivity of benzyl aldehyde reached to 63.2% and 89. 1%, respectively, after catalyst was used for four times.