Hydrogen adsorption states on silica-supported Ru–Ag and Ru–Cu bimetallic catalysts investigated via microcalorimetry

The nature of hydrogen adsorption states on silica supported Ru, Ru–Ag and Ru–Cu was investigated using microcalorimetry and selective hydrogen chemisorption. The differential heats of hydrogen adsorption as a function of hydrogen coverage were determined for Ru and bimetallics with varying Ag and C...

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Bibliographic Details
Published in:Thermochimica acta 1998-03, Vol.312 (1), p.105-114
Main Authors: Narayan, R.L, King, T.S
Format: Article
Language:English
Subjects:
Hydrogen adsorption
Microcalorimetry
Ru bimetallic catalysts
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Summary:The nature of hydrogen adsorption states on silica supported Ru, Ru–Ag and Ru–Cu was investigated using microcalorimetry and selective hydrogen chemisorption. The differential heats of hydrogen adsorption as a function of hydrogen coverage were determined for Ru and bimetallics with varying Ag and Cu contents. The initial heats of hydrogen adsorption (differential heat at coverages approaching zero) were found to be similar on all three catalyst systems suggesting the absence of effects that directly alter the chemisorptive bond (e.g. electron transfer between Ru and the added metal). The addition Ag to Ru significantly reduced the total amount of hydrogen adsorbed per surface Ru atom. That is, the stoichiometry of adsorption was altered by the addition of Ag even though Ag does not adsorb hydrogen. Similarly, the addition of Cu reduced the amount of hydrogen adsorbed per surface metal atom. In both cases, the reduced amount of hydrogen adsorbed per surface atom (adsorptive stoichiometry) was associated with the loss of hydrogen adsorbed from weak and intermediate energy adsorption states (
ISSN:0040-6031
1872-762X
DOI:10.1016/S0040-6031(97)00444-9