title: Understanding the redox behaviour of PbCrO4 and its application in selective hydrogen combustion.
abstract: The performance of PbCrO(4) during reduction/oxidation cycles has been studied over the temperature range 673-873 K. During thermal treatment in an inert atmosphere, PbCrO(4) is stable up to 773 K. At higher temperatures, it decomposes rapidly and irreversibly to Pb(2)(CrO(4))O. Moreover, the redox cycling of Pb(2)(CrO(4))O is also irreversible at 873 K when the reduction semi-reaction is prolonged beyond 3 min. Taking a standard 2 min cyclic treatment, we demonstrate that the surface reduction/oxidation of Pb(2)(CrO(4))O is exothermic between 773-873 K. In contrast, the redox cycling of PbCrO(4) is endothermic at 673 K. These findings demonstrate for the first time the potential of Pb(2)(CrO(4))O as a solid oxygen reservoir for the oxidative dehydrogenation of alkanes; especially at T ≥ 773 K, where H(2) oxidation by Pb(2)(CrO(4))O is exothermic. Preliminary kinetic studies suggest that Pb(2)(CrO(4))O reduction and oxidation both proceed through a "3D diffusion of the reacting front" mechanism. Our results open up opportunities for developing energy-efficient oxidative dehydrogenation routes to commercially important olefins.
authors.affiliation: Van't Hoff Institute for Molecular Sciences, University of Amsterdam, P.O. Box 94157, 1090 GD Amsterdam, The Netherlands.
authors.forename: Santiago
authors.initials: S
authors.lastname: Gómez-Quero
authors.forename: Carlos
authors.initials: C
authors.lastname: Hernández-Mejía
authors.forename: Ruud
authors.initials: R
authors.lastname: Hendrikx
authors.forename: Gadi
authors.initials: G
authors.lastname: Rothenberg