Mechanism for the synthesis of dimethyl carbonate from oxidative carbonylation of methanol

There are a series of problems on traditional catalysis in the synthesis of DMC from oxidative carbonylation of methanol,including the corrosion to instrument and the loss of catalyst activity for the existence of chlorine.Modified copper catalysts were obtained by loading and adding promoter or ligand and some problems were ameliorated.The modified catalysts were introduced and the mechanisms for them were studied.An active intermediate for CuCl2or CuCl loaded catalyst is Cu(OCH3)Cl or Cu2(OH)3Cl.When CuCl was mixed with ligand,the formation of methoxide species was affected by the structure,kind and amount of ligand.Free-chloride catalyst was realized for the Cu-zeolite catalyst prepared by solid-state exchange,but with low activity.When Si,Al and Ti oxide were used as zeolites,modifications for the surface of these oxides were implemented and catalytic activity was enhanced.Though the rate-determing step is the insertion of CO to the methoxide species for most of copper catalyst,differences remained in the formation of methoxide species and the production of the insertion of CO to the methoxide species.Further study of the reaction mechanism for the catalysts is still the focus in the future.