Kinetic Study of Selective CO Oxidation over Pt-Co-Ce/Al_2O_3 Catalyst in Hydrogen-Rich Streams

The kinetics of the selective CO oxidation was studied in a fixed-bed microreactor at atmospheric pressure over Pt-Co-Ce/Al2O3 catalyst, which was prepared using the incipient to wetness co-impregnation technique. Intrinsic kinetic data were obtained in the initial rate region using 8 different sets of CO and O2 concentrations, each at 2 space times, i.e. 2 catalyst loadings, at 110 °C. The kinetic models based on elementary reaction steps were constructed and tested using nonlinear regression analysis with Levenberg-Marquardt algorithm. The alternative models proposed for the similar catalytic systems in the literature were also tested. It was found that Pt-Co-Ce/Al2O3 acts as a bifunctional catalyst (assuming ceria and cobalt sites are identical) and the reactions proceed via a Langmuir-Hinshelwood (L-H) type mechanism. However, no further discrimination could be made among the models based on bifunctionality and L-H kinetics. An empirical power law model was also tested and the results were found to be quite satisfactory.