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Surface and structural properties of pt/ceo2catalyst under preferential co oxidation in hydrogen (PROX) |
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| Authors: | Detre Teschner Attila Wootsch Olga Pozdnyakova Hermann Sauer Axel Knop-Gericke Robert Schl?gl |
| Affiliation: | (1) Department of Inorganic Chemistry, Fritz-Haber-Institut der MPG, Institute of Isotopes, CRC, HAS,, Faradayweg 4-6, 14195 Berlin, Germany Budapest, Konkoly-Thege M. 29-33, H-1525, Hungary;(2) Institute of Isotopes, CRC, HAS,, Budapest, Konkoly-Thege M. 29-33, H-1525, Hungary;(3) Institute of Isotopes, CRC, HAS,, Budapest, Konkoly-Thege M. 29-33, H-1525, Hungary;(4) Department of Inorganic Chemistry, Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany;(5) Department of Inorganic Chemistry, Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany;(6) Department of Inorganic Chemistry, Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, Germany |
| Abstract: | Summary Preferential oxidation of CO in the presence of excess hydrogen was studied on Pt/CeO2with 5% metal loading. Catalytic data were similar to those observed on 1% Pt/CeO2earlier [16]. The optimum temperature region is T￡373 K; conversion and selectivity of CO oxidation strongly decreased at higher temperatures. High-pressure XPS indicated CO adsorbed on platinum particles and significant amount of water on the ceria surface. The top-most ceria surface re-oxidized as small amount of oxygen (3%) was introduced into the H2/CO feed. Despite this surface re-oxidation, high-resolution TEM after reaction indicated oxygen deficient ceria bulk structure, in which the defects formed a super-cell, with CeO1.695structure. The defective ceria is suggested to play an important role stabilizing the hydrogen bonded surface water, which (i) suppresses further hydrogen oxidation and (ii) reacts at the metal/support interface with linearly adsorbed CO in a low temperature water-gas-shift type reaction to produce CO2. |
| Keywords: | platinum ceria HRTEM Hydrogen purification preferential CO oxidation PROX Pt/CeO2 high pressure XPS |
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