用于甲醇直接气相氧化羰基化的负载铜催化剂

 采用浸渍法制备了负载型铜基催化剂,并用其催化甲醇直接气相氧化羰基化合成碳酸二甲酯(DMC), 考察了浸渍溶剂、载体、助催化剂和铜含量的影响. 结果表明,以CuCl为活性组分原料、浓氨水为浸渍溶剂和活性炭为载体制得的负载铜催化剂显示出很高的催化活性,在特定的反应条件下,该催化剂上甲醇的转化率可达27.7%, DMC选择性可达95%. 分子筛负载的铜催化剂上甲醇的转化率低于1%, 但是生成DMC的选择性高达100%. 催化剂活性随着Cu负载量的增加而增大,但负载量过高可引起甲醇的过度氧化反应,导致DMC选择性下降. 催化剂中添加KOH或钯化合物,有利于提高以CuCl2为活性组分原料制得的铜催化剂的活性,但同时也促进了副反应的发生. 随着反应时间的延长,催化剂的活性组分流失,活性下降,但是生成DMC的选择性维持在95%左右.

Supported Copper Catalysts for Direct Vapor-Phase Oxycarbonylation of Methanol

The supported copper catalysts were prepared by the incipient wetness impregnation method and used for direct vapor-phase oxycarbonylation of methanol to dimethyl carbonate (DMC). The effects of impregnation solvents, supports, promoters, and Cu loading on the catalytic activity were investigated. The results showed that the activated carbon (AC)-supported copper catalyst prepared using CuCl as the starting material and ammonia as the impregnation solvent showed high catalytic activity for methanol oxycarbonylation. Under the specified conditions, methanol conversion and DMC selectivity reached 27.7% and 95%, respectively. Compared with the AC support, the zeolite-supported copper catalyst gave a methanol conversion of less than 1% and a selectivity for DMC as high as 100%. The catalytic activity increased with the increase of copper loading. However, the DMC selectivity decreased when the copper loading exceeded a certain value. The addition of palladium compounds or potassium hydroxide enhanced the activity of the catalyst prepared using CuCl_2 as the starting material, but the side reactions were promoted simultaneously. During the reaction for 60 h , DMC selectivity maintained stable while methanol conversion decreased due to the loss of active components.