Kinetic study for the direct synthesis of dimethyl carbonate from methanol and CO2 over CeO2 at high pressure conditions

The kinetics for the direct synthesis of dimethyl carbonate was studied over CeO2 at high pressure conditions in a batch reactor. Langmuir-Hinshelwood and Eley-Rideal mechanisms were proposed and compared by the performance of the respective reaction rate expression in fitting to the experimental kinetic data. The reactions were held at different temperatures (378-408 K), CO2/methanol molar ratios (1.1-4.0) and pressures (15-20 MPa) in order to adjust the kinetic parameters. An activation energy of 106 kJ mol(-1), as well as the standard enthalpy and Gibbs energy of reaction (-20.10 and 31.50 kJ mol(-1)) were calculated from experiments. Furthermore, the changes in pressure revealed an effect on the kinetic constant, with an activation volume equal to -0.208 cm(3) mol(-1). (c) 2013 Elsevier B.V. All rights reserved.