Adsorption Studies of Gases on Pt−Rh Bimetallic Catalysts by Reversed-Flow Gas Chromatography

Abstract

In the present work, the relatively new technique of reversed-flow gas chromatography was applied for the study of adsorption of carbon monoxide, oxygen, and carbon dioxide on Pt−Rh bimetallic catalysts. Using suitable mathematical analysis, equations were derived by means of which rate constants for adsorption, desorption, and disproportionation reaction were calculated. From the variation of these rate constants with temperature and the nature of the catalyst (Pt content), as well as from the finding that the CO adsorption is a dissociative process, useful conclusions concerning the mechanism for the CO oxidation reaction over Pt−Rh bimetallic catalysts were extracted. The catalytic fractional conversions for the CO disproportionation reaction were found to be higher for the Pt−Rh bimetallic catalysts than those for the pure Pt catalyst, indicating the presence of beneficial Pt−Rh synergism.