Mesoporous bimetallic PdCl_2-CuCl_2 catalysts for dimethyl carbonate synthesis by vapor phase oxidative carbonylation of methanol

摘要

Dimethyl carobnate (DMC) synthesis reaction by oxidative carobnylation of methanol has been studied in a flow reaction system at atmospheric pressure in thepresence of quaternary ammonium salt (QAS)-promotede bimetallic PdCl_2-CuCl_2 catalysts system supported on mesoporous HMS silica.The effects of the various QAS promoters,the promoter doping level and the Cu/Pd mole ratio were investigated,as well as the reaction conditions on the catlaytic reactivares. The results showed that the tetrabutylammonium bromide (TBAB)promotede PdCl_2-CuCl_2/HMS catlayst system has the best catlaytic performance. The characterization of TBAB promoter is to facilitate the Pd(0)/Pd(II) and Cu(II)/Cu(I) redox processes. The formation of substantial amounts of surface stabilized cuprous species on the bimetallic HMS catalysts may account for the significant enhancement of the catalytic performance in DMC synthesis.