Oxidation of Propylene over Pd(5 5 1): Temperature Hysteresis Induced by Carbon Deposition and Oxygen Adsorption Full article
Journal |
Catalysis Today
ISSN: 0920-5861 , E-ISSN: 1873-4308 |
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Output data | Year: 2015, Volume: 244, Pages: 29-35 Pages count : 7 DOI: 10.1016/j.cattod.2014.08.023 | ||||||||
Tags | Heterogeneous catalysis, Palladium, Propylene oxidation, Temperature hysteresis | ||||||||
Authors |
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Affiliations |
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Funding (2)
1 | Russian Foundation for Basic Research | 12-03-00766 |
2 | The Ministry of Education and Science of the Russian Federation |
Abstract:
The oxidation of propylene over a Pd(5 5 1) single crystal surface has been studied by X-ray photoelectron spectroscopy (XPS) and temperature-programmed reaction spectroscopy during both heating and cooling in various oxygen/propylene mixtures. In all the experiments, the partial pressure of propylene was approximately 1 × 10−7 mbar and the partial pressure of oxygen was varied to achieve molar oxygen/propylene ratios of 1, 3, 10, and 100. Under all these conditions, we observed a temperature hysteresis: temperature dependences of the catalyst activity and product distribution were different during heating and cooling. It was shown that the temperature hysteresis was due to concurrent accumulation of carbon and oxygen atoms on the palladium surface. At low temperatures, a high concentration of carbonaceous deposits detected by XPS resulted in a low catalytic activity due to blocking of the palladium surface. Increasing temperature led to full dehydrogenation of the carbonaceous species and dissolution of carbon atoms into subsurface palladium layers. As a result, even under oxygen-rich conditions, the formation of a PdCx phase was detected by XPS at 373 K. This process had no influence on the selectivity in the oxidation of propylene at least under UHV conditions. A shift of selectivity toward CO2 was found to result from an increase in the oxygen concentration on the palladium surface. The state with a low catalytic activity in the oxidation of propylene was associated with palladium in the metallic state covered by carbon deposits. The high-active state of palladium was associated with palladium in the metallic state with a high concentration of chemisorbed oxygen and a moderate concentration of a surface oxide. Bulk PdO was not detected by XPS under all conditions used.
Cite:
Matveev A.V.
, Kaichev V.V.
, Saraev A.A.
, Gorodetskii V.V.
, Knop-Gericke A.
, Bukhtiyarov V.I.
, Nieuwenhuys B.E.
Oxidation of Propylene over Pd(5 5 1): Temperature Hysteresis Induced by Carbon Deposition and Oxygen Adsorption
Catalysis Today. 2015.
V.244. P.29-35. DOI: 10.1016/j.cattod.2014.08.023
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Oxidation of Propylene over Pd(5 5 1): Temperature Hysteresis Induced by Carbon Deposition and Oxygen Adsorption

Files:
Full text from publisher
Dates:
Submitted: | Mar 31, 2014 |
Accepted: | Aug 19, 2014 |
Published online: | Sep 12, 2014 |
Published print: | Apr 1, 2015 |
Identifiers:
Web of science: | WOS:000349088000005 |
Scopus: | 2-s2.0-84922879246 |
Elibrary: | 24008328 |
Chemical Abstracts: | 2014:1510748 |
Chemical Abstracts (print): | 162:286988 |
OpenAlex: | W2022352502 |