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 had 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 methanol conversion of less than 1% and DMC selectivity as high as 100%. The catalytic activity increased with increasing copper loading. However, the DMC selectivity decreased when the copper loading exceeded a certain amount. The addition of palladium compounds or potassium hydroxide enhanced the activity of the catalyst prepared using CuCl2 as the starting material; however, the side reactions were promoted simultaneously. During the reaction for 60 h, the DMC selectivity remained stable, whereas methanol conversion decreased because of the loss of active components.