caa a22 4500 475843878 CHVBK 20180406123908.0 cr unu---uuuuu 170329e20001201xx s 000 0 eng 10.1023/A:1009098714759 doi (NATIONALLICENCE)springer-10.1023/A:1009098714759 Surface reactions on inverse model catalysts: CO adsorption and CO hydrogenation on vanadia- and ceria-modified surfaces of rhodium and palladium [Elektronische Daten] [Konrad Hayek, Bernd Jenewein, Bernhard Klötzer, Wolfgang Reichl] Reducible transition metal oxides are well-known promoters of the hydrogenation of CO on noble metal surfaces. In this study the promotional effect of vanadia and ceria adlayers on Rh and Pd surfaces was investigated with emphasis on the effect of the oxidation state on CO adsorption and catalytic activity. "Inverse supported catalysts” were prepared by UHV deposition of V and Ce on the noble metal surface (Rh(111), Pd(111) or Rh foil). After oxidation and specified reduction, the reaction kinetics on polycrystalline Rh was measured at atmospheric pressure, and the molecular and dissociative chemisorption of CO on Rh(111) and Pd(111) and the methanation kinetics on Rh(111) were investigated by molecular beam techniques. On Rh(111), the probability of CO dissociation and the reaction rate are enhanced by submonolayer VO x deposits. Local pressures between 10-2 and 1 mbar are sufficient to drive the methanation at 573 K with measurable amounts of products, accompanied by significant restructuring of the catalyst surface. Although the reaction on Rh is generally promoted by small quantities of vanadia and ceria, the reaction rates depend strongly on the extent and temperature of hydrogen reduction. The observed increase of the reaction rate by reduction up to 673 K can be correlated to concomitant changes of the structure and composition of the VO x deposits. If the reduction temperature is raised above 673 K, metallic V is partially dissolved in the bulk, and the resulting V/Rh subsurface alloy exhibits a particularly high activity. Contrary to vanadia, ceria islands on Rh promote the initial reaction only after a low-temperature reduction, but the activity decreases after reduction above 573 K. Plenum Publishing Corporation, 2000 catalysis nationallicence surface reaction nationallicence single crystal nationallicence rhodium nationallicence vanadium oxide nationallicence cerium oxide nationallicence subsurface alloy nationallicence carbon monoxide nationallicence hydrogen nationallicence CO hydrogenation nationallicence molecular beam nationallicence high-pressure cell nationallicence Hayek Konrad Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut Jenewein Bernd Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut Klötzer Bernhard Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut Reichl Wolfgang Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut Topics in Catalysis Kluwer Academic Publishers-Plenum Publishers 14/1-4(2000-12-01), 25-33 1022-5528 14:1-4<25 2000 14 11244 https://doi.org/10.1023/A:1009098714759 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1009098714759 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hayek Konrad Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut NATIONALLICENCE 700 1- Jenewein Bernd Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut NATIONALLICENCE 700 1- Klötzer Bernhard Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut NATIONALLICENCE 700 1- Reichl Wolfgang Institut für Physikalische Chemie, Universität Innsbruck, Innrain 52a, A-6020, Innsbruck, Austria aut NATIONALLICENCE 773 0- Topics in Catalysis Kluwer Academic Publishers-Plenum Publishers 14/1-4(2000-12-01), 25-33 1022-5528 14:1-4<25 2000 14 11244 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer