Poisoning of Pt/C catalysts by CO and its consequences over the kinetics of hydrogen chemisorption |
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Authors: | Philippe Trens Robert Durand Bernard Coq Christophe Coutanceau Sverine Rousseau Claude Lamy |
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Affiliation: | aInstitut Charles Gerhard de Montpellier, UMR 5253 CNRS/ENSCM/UM2/UM1, “Matériaux Avancés pour la Catalyse et la Santé”, Ecole Nationale Supérieure de Chimie de Montpellier, 8 rue de l’Ecole Normale, 34296 Montpellier Cedex 5, France;bLaboratoire de Catalyse en Chimie Organique, UMR 6503 CNRS – Université de Poitiers, 40, Avenue du Recteur Pineau, 86022 Poitiers Cedex, France |
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Abstract: | The initial rate of hydrogen dissociation was studied as a function of irreversible CO coverage at 353 K on 30 wt.% Pt/carbon catalysts (Pt/C) prepared according to different processes. The Pt/C catalysts exhibit similar Pt dispersion (D 0.07) and mean Pt particles size (dp 16 nm). The turnover frequency (number of hydrogen molecules dissociated per CO-free surface Pt atom) was determined as a function of CO coverage from 0.0 to 0.8. The evolution of TOF as a function of CO coverage is in agreement with the model of CO adsorbing on low coordination sites (edges, corners) and then spreading across the faces to grow islands as Brandt suggested in the past (R.K. Brandt, M.R. Hughes, L.P. Bourget, K. Truszkowska, R.G. Greenler, Surf. Sci. 286 (1993) 15–25). At high CO coverage (0.8), TOF depends on the process by which the Pt/C catalyst was prepared. In particular, a Pt/C elaborated according to a colloidal process exhibits a low sensitivity to CO poisoning with an increase of TOF by one order of magnitude. |
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Keywords: | H2 dissociation CO poisoning Pt/C Fuel cell Kinetics |
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