Deactivation of Ru Catalysts under Catalytic CO Oxidation by Formation of Bulk Ru Oxide Probed with Ambient Pressure XPS

WOS: 000321236400022The surface science approach of using model catalysts in conjunction with the development of in situ spectroscopic tools, such as ambient pressure X-ray photoelectron spectroscopy (AP-XPS), offers a synergistic strategy for obtaining a substantially better understanding of deactivation phenomena. In this study, we investigated the nature of Ru oxides on a Ru polycrystalline film under oxidizing, reducing, and catalytic CO oxidation reaction conditions. Thus, bulk Ru oxide was easily formed on such Ru catalysts, the growth of which was dependent on reaction temperature. Once formed, such an oxide is irreversible and cannot be completely removed even under reducing conditions at elevated temperatures (200 degrees C). Our reaction studies showed substantial deactivation of the Ru film during catalytic CO oxidation, and its activity could be partially recovered after reduction pretreatment. Such continuous deactivation of a Ru film is correlated with irreversibly formed bulk Ru oxide, as shown by AP-XPS. Such in situ spectroscopic evidence of the transition of oxides to a catalytically inactive state can enable more effective design of catalysts with less deactivation.WCU (World Class University) program through the National Research Foundation [31-2008-000-10055-0, 2012R1A2A1A01009249]; Research Center Program of IBS (Institute for Basic Science) [CA1201]; Fundamental R&D Program for Core Technology of Materials; Ministry of Knowledge Economy, Republic of KoreaThis work was supported by the WCU (World Class University) program (31-2008-000-10055-0 and 2012R1A2A1A01009249) through the National Research Foundation, the Research Center Program (CA1201) of IBS (Institute for Basic Science) and from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Korea