title: Inhibition of ammonia poisoning by addition of platinum to Ru/α-Al2 O3 for preferential CO oxidation in fuel cells.
abstract: In polymer electrolyte fuel cell (PEFC) systems, small amounts of ammonia (NH3 ) present in the reformate gas deactivate the supported ruthenium catalysts used for preferential oxidation (PROX) of carbon monoxide (CO). In this study, we investigated how the addition of a small amount of platinum to a Ru/α-Al2 O3 catalyst (Pt/Ru=1:9 w/w) affected the catalyst's PROX activity in both the absence and the presence of NH3 (130 ppm) under conditions mimicking the reformate conditions during steam reforming of natural gas. The activity of undoped Ru/α-Al2 O3 decreased sharply upon addition of NH3 , whereas Pt/Ru/α-Al2 O3 exhibited excellent PROX activity even in the presence of NH3 . Ruthenium K-edge X-ray absorption near-edge structure (XANES) spectra indicated that in the presence of NH3 , some of the ruthenium in the undoped catalyst was oxidized in the presence of NH3 , whereas ruthenium oxidation was not observed with Pt/Ru/α-Al2 O3 . These results suggest that ruthenium oxidation is retarded by the platinum, so that the catalyst shows high activity even in the presence of NH3 .
authors.affiliation: Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245 (Japan); Department of Applied Chemistry, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan), Fax: (+81) 97-554-7979.
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Sato
authors.forename: Sho
authors.initials: S
authors.lastname: Yagi
authors.forename: Shuhei
authors.initials: S
authors.lastname: Zaitsu
authors.forename: Godai
authors.initials: G
authors.lastname: Kitayama
authors.forename: Yuto
authors.initials: Y
authors.lastname: Kayada
authors.forename: Kentaro
authors.initials: K
authors.lastname: Teramura
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Takita
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Nagaoka
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D000641:Ammonia / Q000032:analysis*; D002248:Carbon Monoxide / Q000737:chemistry*; D011211:Electric Power Supplies; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D010984:Platinum; D000641:Ammonia; D002248:Carbon Monoxide; D012428:Ruthenium; D000537:Aluminum Oxide
keywords: X-ray absorption spectroscopy; fuel cells; heterogeneous catalysis; hydrogen; natural gas