CuCl2 immobilized on amino-functionalized MCM-41 and MCM-48 and their catalytic performance toward the vapor-phase oxy-carbonylation of methanol to dimethylcarbonate

Amino-functionalized MCM-41 and MCM-48 mesoporous silicas were used to immobilize CuCl2 for the vapor-phase oxy-carbonylation of methanol to produce DMC. Higher reaction rates and better catalytic stability were obtained with CuCl2 supported onto amino-functionalized MCM-41 and MCM-48 in the DMC yield in comparison with those with CuCl2 supported on nonfunctionalized mesoporous silicas under identical conditions. The best DMC yield was obtained with a CuCl2 loading of about 10 wt%, which corresponds to the N/Cu atomic ratios of 1.5 and 2.4 in the CuCl2/1N-MCM-41 and CuCl2/2N-MCM-41, respectively. Characterizations with XRD, N2 adsorption, XPS, and HRTEM revealed that the regular hexagonal/cubic arrays in MCM-41 and MCM-48 were retained after the amino-functionalization and the immobilization of CuCl2 with a loading weight lower than 20 wt%. The Cu species in the catalysts with loadings lower than 10 wt% were mainly located and finely dispersed in the mesopores of amino-functionalized MCM-41 and MCM-48 through a coordinative complexation with the amino groups, forming (N)2 → Cu2+ complex species. The better performance of CuCl2 on amino-functionalized MCM-41 and MCM-48 for the DMC production via vapor-phase oxy-carbonylation of methanol may be ascribed to the high dispersion of active sites at regular mesopores, in addition to the accelerated redox process of Cu2+/Cu+ in the complex species.