Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10244386 | Journal of Catalysis | 2005 | 8 Pages |
Abstract
We have investigated the preferential oxidation (PROX) of carbon monoxide at Pt/mordenite (Pt/M), Fe/mordenite (Fe/M), and Pt-Fe/mordenite (Pt-Fe/M) for a purification of reformates to supply polymer electrolyte fuel cells (PEFCs). Pt-Fe/M exhibited remarkable PROX activity up to an extremely high space velocity (i.e., ca. 100% selectivity, SV=â¼105hâ1) even at 50â°C, although Pt/M and Fe/M had negligibly small PROX activity. CO, H2, and O2 chemisorption measurements demonstrated that Pt sites act as adsorption sites for CO and/or H2 and Fe (dominantly FeO) sites only for O2, so that the addition of Fe to Pt/M can preserve O2 adsorption sites for the PROX reaction even in CO/excess H2 gas flow. The poor reactivity of Pt/M and Fe/M can be ascribed to the lack of CO and/or O2 adsorption as the essential requisite for the Langmuir-Hinshelwood mechanism. We propose the so-called “bifunctional mechanism” for the distinctive performance at Pt-Fe/M, where the Pt site acts as a CO adsorption site and the Fe site acts as an O2 dissociative-adsorption site and enhances the surface reaction between the reactants on the neighboring sites.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Catalysis
Authors
Masashi Kotobuki, Akiko Watanabe, Hiroyuki Uchida, Hisao Yamashita, Masahiro Watanabe,