title: The beneficial effect of hydrogen on CO oxidation over Au catalysts. A computational study.
abstract: Density functional theory calculations have been carried out to explore the effect of hydrogen on the oxidation of CO in relation to the preferential oxidation of CO in the presence of excess hydrogen (PROX). A range of gold surfaces have been selected including the (100), stepped (310) surfaces and diatomic rows on the (100) surface. These diatomic rows on Au(100) are very efficient in H-H bond scission. O(2) hydrogenation strongly enhances the surface-oxygen interaction and assists in scission of the O-O bond. The activation energy required to make the reaction intermediate hydroperoxy (OOH) from O(2) and H is small. However, we postulate its presence on our Au models as the result of diffusion from oxide supports to the gold surfaces. The OOH on Au in turn opens many low energy cost channels to produce H(2)O and CO(2). CO is selectively oxidized in a H(2) atmosphere due to the more favorable reaction barriers while the formation of adsorbed hydroperoxy enhances the reaction rate.
authors.affiliation: Physics Division, Pakistan Institute of Science and Technology, P. O. Nilore, Islamabad 44000, Pakistan. ahmohal@yahoo.com
authors.forename: Akhtar
authors.initials: A
authors.lastname: Hussain
authors.forename: Jose
authors.initials: J
authors.lastname: Gracia
authors.forename: J W
authors.initials: JW
authors.lastname: Niemantsverdriet
authors.forename: B E
authors.initials: BE
authors.lastname: Nieuwenhuys
mesh_terms: D000327:Adsorption; D002245:Carbon Dioxide / Q000737:chemistry; D002248:Carbon Monoxide / Q000737:chemistry*; D002384:Catalysis; D003198:Computer Simulation; D006046:Gold / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D013499:Surface Properties
chemical_list: D010087:Oxides; D002245:Carbon Dioxide; D006046:Gold; D002248:Carbon Monoxide; D006859:Hydrogen; D006861:Hydrogen Peroxide
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