CO2-selective methanol steam reforming on In-doped Pd studied by in situ X-ray photoelectron spectroscopy

Author

• Christoph Rameshan, University of Innsbruck; Max Planck Society
• Harald Lorenz, University of Innsbruck
• Lukas Mayr, University of Innsbruck
• Simon Penner, University of Innsbruck
• Dmitry Zemlyanov, Birck Nanotechnology Center, Purdue UniversityFollow
• Rosa Arrigo, Max Planck Society
• Michael Haevecker, Max Planck Society
• Raoul Blume, Max Planck Society
• Axel Knop-Gericke, Max Planck Society
• Robert Schloegl, Max Planck Society
• Bernhard Kloetzer, University of Innsbruck

Abstract

In situ X-ray photoelectron spectroscopy (in situ XPS) was used to study the structural and catalytic properties of Pd-In near-surface intermetallic phases in correlation with previously studied PdZn and PdGa. Room temperature deposition of similar to 4 monolayer equivalents (MLEs) of In metal on Pd foil and subsequent annealing to 453 K in vacuum yields a similar to 1:1 Pd/In near-surface multilayer intermetallic phase. This Pd1In1 phase exhibits a similar "Cu-like" electronic structure and indium depth distribution as its methanol steam reforming (MSR)-selective multilayer Pd1Zn1 counterpart. Catalytic characterization of the multilayer Pd1In1 phase in MSR yielded a CO2-selectivity of almost 100% between 493 and 550 K. In contrast to previously studied In2O3-supported PdIn nanoparticles and pure In2O3, intermediate formaldehyde is only partially converted to CO2 using this Pd1In1 phase. Strongly correlated with PdZn, on an In-diluted PdIn intermetallic phase with "Pd-like" electronic structure, prepared by thermal annealing at 623 K, methanol steam reforming is suppressed and enhanced CO formation via full methanol dehydrogenation is observed. To achieve CO2-TOF values on the isolated Pd1In1 intermetallic phase as high as on supported PdIn/In2O3, at least 593 K reaction temperature is required. A bimetal-oxide synergism, with both bimetallic and oxide synergistically contributing to the observed catalytic activity and selectivity, manifests itself by accelerated formaldehyde-to-CO2 conversion at markedly lowered temperatures as compared to separate oxide and bimetal. Combination of suppression of full methanol dehydrogenation to CO on Pd1In1 inhibited inverse water-gas-shift reaction on In2O3 and fast water activation/conversion of formaldehyde is the key to the low-temperature activity and high CO2-selectivity of the supported catalyst. (C) 2012 Elsevier Inc. All rights reserved.

Keywords

PdIn near-surface alloy; Pd foil; Methanol dehydrogenation; Methanol steam reforming; Water activation; In situ X-ray photoelectron spectroscopy (AP-XPS); WATER-GAS SHIFT; NEAR-SURFACE ALLOYS; MEAN FREE PATHS; HYDROGEN-PRODUCTION; ZN; CATALYSTS; PD(111); ADSORPTION; SELECTIVITY; GROWTH

DOI

10.1016/j.jcat.2012.08.008

Citation

Journal of Catalysis Volume 295, November 2012, Pages 186–194

Date of this Version

11-2012

Recommended Citation

Rameshan, Christoph; Lorenz, Harald; Mayr, Lukas; Penner, Simon; Zemlyanov, Dmitry; Arrigo, Rosa; Haevecker, Michael; Blume, Raoul; Knop-Gericke, Axel; Schloegl, Robert; and Kloetzer, Bernhard, "CO2-selective methanol steam reforming on In-doped Pd studied by in situ X-ray photoelectron spectroscopy" (2012). Birck and NCN Publications. Paper 1108.
http://dx.doi.org/10.1016/j.jcat.2012.08.008