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

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 47.6 DMC mol·(Cu mol)− 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 0.011 mol·L− 1. Furthermore, a plausible reaction mechanism was suggested on the basis of the experimental data.

The coordination environment and the thermal stability of the complexes influence the steric and electronic properties of the catalytic centers and the catalytic behaviors.Figure optionsDownload as PowerPoint slide