采用原位漫反射红外光谱法研究了Cuβ催化剂上氧化羰基合成碳酸二甲酯(DMC)的反应机理,考察了甲醇、一氧化碳和DMC的单独吸附及混合气吸附.结果表明,Cuβ催化剂上只存在一种活性位,位于六元环中；氧气能够氧化吸附态的甲醇产生甲氧基和水；DMC吸附在Cuβ催化剂上时,以羰基中的氧原子吸附在活性位上更加稳定；反应存在生成单甲氧基物种和双甲氧基物种两条路径,单甲氧基物种与CO反应生成单甲基碳酸盐物种(MMC),MMC再与甲氧基反应生成DMC；CO插入双甲氧基物种也可以得到DMC.在Cuβ催化剂上更倾向于进行CO插入双甲氧基物种这一路径.%The mechanism of oxidative carbonylation of methanol to dimethyl carbonate (DMC) over Cu/3 catalyst was investigated by using in situ DRIFTS; the adsorption of single methanol, carbon monoxide and DMC as well as their mixtures on the Cu/3 catalyst were considered. The results indicated that methoxide species are formed when methanol is adsorbed on the catalyst due to presence of CuOx. Only one type of active sites that are located in the six-membered ring of β zeolite is found, over which adsorbed methanol can be oxidized to methoxide and water. DMC is adsorbed on the catalyst through the contact of the oxygen atom in carbonyl group with the active sites. There were two pathways for the oxidative carbonylation: by the mono-methoxide pathway, carbon monoxide can react with mono-methoxide species to form monomethyl carbonate (MMC) and MMC then reacts with methoxide to form DMC, or by the di-methoxide pathway, DMC is formed through inserting of carbon monoxide in the di-methoxide species; latter one is more favorable 展开▼
