Direct synthesis of dimethyl carbonate over activated carbon supported Cu-based catalysts

Abstract

A series of Cu-based catalysts have been synthesized by the conventional incipient wetness impregnation and utilized in the dimethyl carbonate (DMC) synthesis. The effects of preparation and reaction conditions on the catalytic activities were intensively investigated. The surface properties and morphology of the employed catalysts were fully characterized using TPD-NH 3, XRD, SEM-EDX, TEM and XPS techniques. Structural investigation indicated that Cu 0, Cu + and Cu 2+ co-existed on the surface of employed catalyst and they were the main active species in DMC synthesis. Calcining the catalyst at proper temperature could promote the formation of active species, hence the activity of CuCl 2/AC catalyst. Maintaining proper and effective Cu structure on AC surface will promote more selective DMC formation. Catalytic evaluation suggested that regardless of catalyst compositions, the optimal reaction conditions for DMC synthesis were found to be 393 K and 1.2 MPa. DMC formation rate was strongly related to the Cu loading, calcination temperature and Cl/Cu ratio. Under the optimal conditions of 7 wt% Cu loading and 673 K calcination, the highest DMC formation rate of 4.77 mmol h −1 and DMC selectivity of 90.1% could be achieved, respectively.