Study of the sorption of carbon monoxide, oxygen and carbon dioxide on platinum–rhodium alloy catalysts by a new gas chromatographic methodology

Abstract

The mechanism of the CO oxidation reaction over Pt–Rh alloy catalysts was extracted from the adsorption of CO, O 2 and CO 2 on these catalysts. Reversed-flow gas chromatography was applied to the study of these important sorption processes. Using suitable mathematical analysis, equations were derived by means of which rate constants for the adsorption and desorption of CO, O 2 and CO 2 on and from the Pt–Rh bimetallic catalysts were determined. Temperature dependence of the rate constants for the sorption processes were also determined and the Arrhenius parameters for the adsorption and desorption were calculated. The dependence of activation energies for adsorption, desorption and disproportionation reaction on the catalyst Pt content indicates that for the CO oxidation reaction the most active is the Pt-rich catalyst, while for the CO disproportionation reaction the most active is the Rh-rich catalyst.