Enhanced stability of Cu/AC catalyst with modified hydrophobic layer for methanol oxidative carbonylation to dimethyl carbonate

Abstract

The by-product water generated in the oxidative carbonylation of methanol to dimethyl carbonate (DMC) causes severe oxidation and deactivation of Cu catalysts, so how to minimize the effect of water on Cu catalysts is a great challenge. Here, we report a strategy to stabilize the Cu+ species in Cu/AC catalyst by hydrophobic modification with methyltriethoxysilane. Compared to Cu/AC catalyst, the modified Cu/AC-CH3 catalyst shows that the crystalline structure and the average Cu particle size were not changed, the BET surface area was slightly decreased while the amount of adsorbed methanol was obviously increased. The catalytic stability of Cu/AC-CH3 was significantly improved with a deactivation rate of only 11.9% compared to Cu/AC catalyst (29.2%). The spent Cu/AC-CH3 shows that the water contact angle remained at 119° and Cu+ species were still present as the main component, which was attributed to the confinement effect of the hydrophobic layer that inhibited the aggregation of Cu particles and prevented the Cu+ species from oxidizing water, thus improving the catalyst stability even in the presence of water. This work provides a practical strategy for improving the stability of Cu-based catalysts in the reaction, which produces water as a by-product.