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J Chem Phys. 2005 Nov 1;123(17):174706.

The application of infrared spectroscopy to probe the surface morphology of alumina-supported palladium catalysts.

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1
Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom.

Erratum in

  • J Chem Phys. 2006 Feb 14;124(6):069901.

Abstract

Five alumina-supported palladium catalysts have been prepared from a range of precursor compounds [palladium(II) nitrate, palladium(II) chloride, palladium(II) acetylacetonate, and tetraamminepalladium(II) tetraazidopalladate(II)] and at different metal loadings (1-7.3 wt %). Collectively, this series of catalysts provides a range of metal particle sizes (1.2-8.5 nm) that emphasize different morphological aspects of the palladium crystallites. The infrared spectra of chemisorbed CO applied under pulse-flow conditions reveal distinct groupings between metal crystallites dominated by low index planes and those that feature predominantly corner/edge atoms. Temperature-programmed infrared spectroscopy establishes that the linear CO band can be resolved into contributions from corner atoms and a combination of (111)(111) and (111)(100) particle edges. Propene hydrogenation has been used as a preliminary assessment of catalytic performance for the 1 wt % loaded catalysts, with the relative inactivity of the catalyst prepared from palladium(II) chloride attributed to a diminished hydrogen supply due to decoration of edge sites by chlorine originating from the preparative process. It is anticipated that refinements linking the vibrational spectrum of a probe molecule with surface structure and accessible adsorption sites for such a versatile catalytic substrate provide a platform against which structure/reactivity relationships can be usefully developed.

PMID:
16375556
DOI:
10.1063/1.2101487

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