Kinetics of CO and H2 oxidation over CuO-CeO2 and CuO catalysts

The kinetics of CO and H-2 oxidation over CuO-CeO2 and CuO catalysts have been investigated. Rate expressions derived from red-ox (Mars-van Krevelen) reaction mechanisms describe satisfactorily the observed kinetic behavior in both oxidation reactions. In the case of CuO-CeO2, both a standard redox expression (with P-O2(n), n similar to 0.07) and a redox expression (with n=1) including the CO adsorption term describe equally well the kinetic results. The promoting effect of CeO2 is present only in CO oxidation and is due mostly to enhancement of the surface reduction rate constant via lowering of the activation energy for surface reduction. On the other hand, the CuO-CeO2 catalyst is actually less active than CuO in H-2 oxidation. The calculated heat of adsorption of CO2, which inhibits both oxidation reactions, is twice as large on CuO compared to CuO-CeO2. (C) 2011 Elsevier B.V. All rights reserved.