A thermodynamically consistent surface reaction mechanism for CO oxidation on Pt

The thermodynamic inconsistency of catalytic combustion reaction mechanisms has been a long-standing, fundamental, and practical problem. Here, we develop a thermodynamically consistent catalytic reaction mechanism for CO oxidation on Pt. First, we propose a modification of the bond index of the unity bond index-quadratic exponential potential (UBI-QEP) semiempirical framework for calculation of the activation energy of the Langmuir-Hinshelwood-type bimolecular surface reaction between co-adsorbed CO* and O*. Thermodynamic consistency is then ensured in the reaction mechanism by combining the semiempirical UBI-QEP theory, statistical mechanics, and constraint-based optimization against experimental data. Atmospheric pressure ignition and ultrahigh vacuum molecular beam experiments are selected as targets for optimization. The optimized mechanism is validated against redundant experiments, including temperature-programmed desorption, temperature-programmed reaction, and molecular beam experiments. Our microkinetic model is able to capture multiple types of data while being thermodynamically consistent over a wide range of conditions. (c) 2005 The Combustion Institute. Published by Elsevier Inc. All rights reserved.