ISSN:
1572-879X
Schlagwort(e):
microcalorimetry
;
IR
;
ruthenium
;
tin
;
copper
;
ethylene
;
CO
;
adsorption
;
DFT
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Abstract Microcalorimetric measurements of the adsorption of H2, CO and C2H4 were conducted on silica-supported Ru, Ru/Sn, Ru/Cu and Cu catalysts; infrared spectroscopic measurements were made of adsorbed CO and C2H4. The adsorption of C2H4 leads to formation of di-σ-adsorbed ethylene and ethylidyne species on Ru/SiO2 at 300 K, with an initial heat of 160 kJ/mol. Ethylene adsorption at 203 K leads to the formation of di-σ-adsorbed ethylene, ethylidyne species and weakly adsorbed π-bonded ethylene. The initial heats are 110, 95 and 75 kJ/mol on Ru/SiO2, 5Ru/Sn/SiO2 and Ru/Cu/SiO2, respectively. Lower heats of CO and C2H4 adsorption are measured on Ru/Cu/SiO2, primarily as a result of these adsorbates binding on both Cu and Ru. Quantum chemical calculations employing density functional theory were performed using (0001) slabs of Ru and Ru/Sn. The results of these calculations indicate that Sn weakens the interaction of π-bonded ethylene, di-σ-bonded ethylene and ethylidyne species with Ru by 41, 23 and 15 kJ/mol, respectively. This behavior is in contrast to the effect of adding Sn to Pt and Pd, for which Sn preferentially weakens the bonding of ethylidyne species to the surface.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1023/A:1019047806971
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