甲醇气相氧化羰基化合成碳酸二甲酯研究进展

介绍了气相直接法和气相间接法的工艺特点,比较了各类活性催化剂的结构特征及其催化性能。分析认为,气相间接法的关键是有效控制第一步反应并确保剧毒NO气体的安全循环使用;气相直接法避免了NO有毒气体的使用。评述了固态离子交换法制备的铜分子筛在气相直接法合成DMC反应中表现出比负载型CuCl2催化剂和Wacker型催化剂更高的稳定性以及较低的腐蚀性,但受分子筛表面酸位的限制,存在交换容量低,残余CuCl难以脱除的不足;而浸渍法制备的无Cl型铜分子筛对DMC的选择性较低;硅基复合氧化物通过改变制备条件可以有效控制表面B酸位的数量、强度及其分布,是基于固态离子交换反应原理制备负载铜催化剂的理想载体材料,值得关注。

Advances in dimethyl carbonate synthesis by gas-phase oxidative carbonylation of methanol

The advances in dimethyl carbonate synthesis by gas-phase oxidative carbonylation of methanol are summarized,the technical features of direct gas-phase process and methylnitrite process are introduced respectively,and the structure characteristics as well as the catalytic performances for different catalysts are presented in details. According to previous research results the key for methylnitrite process is to control the first step reaction and ensure the safety in the application of NO,and the NO-free direct gas-phase process simplifying the reaction mechanismis considered to be a potential commercialization route for DMC synthesis. Compared to CuCl2 loading catalysts and Wacker catalysts,solid state ion-exchange derived copper zeolites present higher stability and lower corrosivity to the reactor. However,limited by the acid sites on the surface of zeolites,only lower ion-exchange rate could be achieved,and it is difficult to remove the residual CuCl adsorbed in the micropores. whereas chloride-free Cu-impregnated zeolite catalysts gave lower DMC selectivity. Si-based mixed oxides are reported as one kind of solid acids,the amounts,intensity and distribution of Brnsted acid sites could be effectively controlled through choosing appropriate preparation conditions, which could be used as ideal support materials to prepare catalysts through solid ion-exchange reaction.