Structure sensitive hydrogen adsorption: Effect of Ag on Ru/SiO{sub 2} catalysts
- Iowa State Univ., IA (United States)
- Middle East Technical Univ., Ankara (Turkey). Chemical Engineering
The dynamics and energetics of hydrogen chemisorption on silica-supported ruthenium and ruthenium-silver bimetallic catalysts were studied by {sup 1}H NMR spectroscopy and microcalorimetry. It was observed that the amount of hydrogen adsorbed on Ru particles having intermediate and low heats of adsorption was significantly reduced with increasing amounts of silver. The desorption and adsorption rate constants, determined from selective excitation NMR experiments, were lower on Ru-Ag catalysts than those on Ru catalysts at the same temperature and hydrogen coverage. The apparent sticking coefficients of hydrogen on a Ru-Ag catalyst with 10 at% Ag were more than 10 times lower than those on a Ru catalyst and were comparable to sticking coefficients reported in the literature for hydrogen adsorbing on Ru single crystal. Thus silver was found to greatly affect both the dynamics and energetics of hydrogen chemisorption on Ru/SiO{sub 2}. However, ensemble and electronic effects did not play any role in causing these effects. It is postulated here that the influence of silver was due to its tendency to selectively segregate to edge, corner, and other low coordination structures on the Ru particle surface. Hence, hydrogen adsorption on these surfaces was found to be structure sensitive.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 659069
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 178; ISSN 0021-9517; ISSN JCTLA5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Characterization of silica-supported Ru-Ag and Ru-Au bimetallic catalysts by hydrogen chemisorption and NMR of adsorbed hydrogen
Characterization of silica-supported Cu monometallic and Ru-Cu bimetallic catalysts by hydrogen chemisorption and NMR of adsorbed hydrogen
Hydrogen chemisorption and mobility on Ru/SiO{sub 2}, K/Ru/SiO{sub 2} and Ru-Ag/SiO{sub 2}
Journal Article
·
Tue May 01 00:00:00 EDT 1990
· Journal of Catalysis; (USA)
·
OSTI ID:6437714
Characterization of silica-supported Cu monometallic and Ru-Cu bimetallic catalysts by hydrogen chemisorption and NMR of adsorbed hydrogen
Journal Article
·
Wed Jan 31 23:00:00 EST 1990
· Journal of Catalysis; (USA)
·
OSTI ID:6437759
Hydrogen chemisorption and mobility on Ru/SiO{sub 2}, K/Ru/SiO{sub 2} and Ru-Ag/SiO{sub 2}
Conference
·
Mon Dec 30 23:00:00 EST 1996
·
OSTI ID:468023