Oxidative Carbonylation of Methanol to Dimethyl Carbonate Over Cu(II)–1,10-Phenanthroline Bromide Complexes

Abstract

In order to develop the catalysts with low corrosiveness for the oxidative carbonylation of methanol to dimethyl carbonate (DMC), CuBr2 was selected as the metal source to prepare Cu coordination compounds, Cu(phen)Br2, [Cu(phen)2Br]Br and [Cu(phen)3]Br2 (phen=1,10-phenanthroline). These complexes were characterized by thermogravimetric analysis and temperature-programmed reduction. Their catalytic performances were investigated. It was found that the metal coordination environments and thermal stability of the complexes played an important role in their catalytic activities. Cu(phen)Br2 exhibited the highest activity due to the lowest steric hindrance, the most positions occupied by the bromide ions and the highest thermal stability. The turnover number was up to 47.6DMCmol·(Cumol)−1 with selectivity of 92.8% under conditions of 120°C, ratio of partial pressure of CO to O2 of 19:1 (below the explosion limit of CO) and catalyst concentration of 0.011mol·L−1. Furthermore, a plausible reaction mechanism was suggested on the basis of the experimental data.