Development of Surface Reaction Mechanisms of CO / O2 on Pt and Rh for Three Way Catalyst based on Gas Phase and Surface Species Analyses

Abstract

ABSTRACT In this study, detailed surface reaction mechanisms for CO/O2 system on Pt/Al2O3 and Rh/Al2O3 have been developed based on the measurements of gaseous and surface species. The conventional conversion rate experiments for gaseous CO to CO2 were conducted with the monolith honeycomb catalyst, and furthermore, the adsorbed surface species were identified with the powdered catalyst by in-situ FTIR under the same conditions as conversion rate experiment. As a result, it was found that only linear CO adsorption was detected for Pt, while twin CO adsorption was detected for Rh. Based on the results, detailed surface reaction mechanisms have been developed for Pt/Al2O3 and Rh/Al2O3. As a result of numerical simulation, it was confirmed that the variations of CO to CO2 conversion rate with temperature were quantitatively reproduced for various O2 concentration conditions. Furthermore, using those reaction mechanisms, CO conversion rate on bimetal, Pt/Rh Al2O3 catalysts were examined for several Pt/Rh ratios. Numerical simulation results for bimetal catalysts were also quantitatively agreed with experimental results for various Pt/Rh ratios as well as CO/O2 ratios.