title: Sulphur poisoning of palladium catalysts used for methane combustion: effect of the support.
abstract: Four different supported palladium catalysts (using alumina, silica, zirconia and titania as supports), prepared by incipient wetness impregnation, were tested as catalysts for methane oxidation in presence of sulphur dioxide. The catalyst supported on zirconia showed the best performance, whereas the silica-supported one showed the fastest deactivation. Temperature-programmed desorption experiments of the poisoned catalysts suggest that SO(2) adsorption capacity of the support plays a key role in the catalyst poisoning. In order to study the effect of promoters, expected to improve the thermal stability and thioresistance of the catalyst, commercial zirconia modified by yttrium and lantane was tested as supports. It was found that the presence of these promoters does not improve the performance of the zirconia-supported catalyst. A deactivation model -- considering two different active sites (fresh and poisoning), pseudo-first order dependence on methane concentration and poisoning rate depending on sulphur concentration and fraction of non-poisoned palladium -- was used for modelling the deactivation behaviour.
authors.affiliation: Department of Chemical and Environmental Engineering, University of Oviedo, C/Julián Clavería s/n, Oviedo, Spain.
authors.forename: Lara S
authors.initials: LS
authors.lastname: Escandón
authors.forename: Salvador
authors.initials: S
authors.lastname: Ordóñez
authors.forename: Aurelio
authors.initials: A
authors.lastname: Vega
authors.forename: Fernando V
authors.initials: FV
authors.lastname: Díez
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D000397:Air Pollution / Q000517:prevention & control; D002384:Catalysis; D008697:Methane / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D010087:Oxides; D013458:Sulfur Dioxide; D010165:Palladium; D008697:Methane