以溶胶-凝胶法合成的HMS分子筛为载体,采用浸渍法制备了一系列的Cr(Ⅲ)/HMS负载型催化剂。考察了不同铬源、负载量对甲苯液相双氧水氧化制备苯甲醛的影响,并利用XRD、FTIR技术对催化剂进行了表征。结果表明,铬离子已经进入到载体HMS的骨架。以硝酸铬为铬源,铬负载量为15%的催化剂效果最好,甲苯的转化率为20.8%,苯甲醛的选择性达31.7%。并对甲苯液相氧化的反应机理作了初步的探讨。
Cr(Ⅲ)/HMS catalysts were prepared by the impregnation method using Cr(NO3)3 as chromium source supported on HMS synthesized by the sol-gel method.The catalysts were characterized by XRD and FTIR.The effect of loading content of Cr and different chromium sources on liquid-phase oxidation of toluene to benzaldehyde with H2O2 was investigated.The results showed that chromium ion was incorporated into the framework of HMS.Cr(Ⅲ)/HMS catalyst with Cr-loading of 15% gave the best catalytic activity.The conversion of toluene and the selectivity for benzaldehyde reached 20.8% and 31.7% respectively.A reaction mechanism is proposed.