from first principles PP-I-1

OP-III-25Ce-O-Pt Active Sites in Ceria Promoted NO x Storage Reduction CatalysisSay Z. 1 , Vovk E.I. 1,2 , Bukhtiyarov V.I. 2 , Özensoy E. 11 Department of Chemistry, Bilkent University, 06800 Ankara, Turkey2 Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russiaozensoy@fen.bilkent.edu.trThe NO x emissions from automobile exhausts have serious destructive effects on the globalecosystem as well as on the human health. NO x storage/reduction (NSR) catalysts which areused for NO x abatement in the absence of additional reducing agents such as poly-urea arecomposed of precious metal nanoparticles which act as redox centres, a high surface areasupport material (γ-Al 2 O 3 ) and a NO x storage component (BaO) that interacts with NO x in theoxidizing conditions forming nitrates and decompose under the reducing conditions releasingharmless N 2 and H 2 O [1,2]. Ceria promotion leads to a significant improvement in a widerange of catalytic processes, including NSR catalysis, owing to its high oxygen storage andoxygen transport capacity [1,3]. In the current work, we investigated the nitration and thesubsequent NO x reduction by H 2 over ceria promoted NSR model catalysts (Pt/CeO 2 /Al 2 O 3and BaO/Pt/CeO 2 /Al 2 O 3 ) by means of in-situ FTIR. The ceria promotion was found tofacilitate the nitrate reduction process. Characterization of the synthesized catalysts by XRD,BET, XPS and Raman spectroscopy revealed the existence of a strong Pt – ceria interactionand the formation of Pt-O-Ce anchoring sites that may be responsible for the higher stabilityand the dispersion of Pt sites. The enhanced NO x reduction efficiency of ceria promoted NSRcatalysts can be explained by the presence of Pt-O-Ce sites operating as oxygen transportcenters facilitating the oxygen transfer between the nitrate species adsorbed on the CeO 2 /BaOsites and the Pt sites activating H 2 . A plausible NO x reduction mechanism is proposed in thelight of the current structural characterization and in-situ spectroscopic results.Authors acknowledge the financial support from Turkish Academy of Sciences (TUBA)through the “Outstanding Young Investigator Grant” and the RFBR (Russia)#12-03-91373-СТа and #10-03-00596-а projects.References:[1] S. Roy and A. Baiker, Chem. Rev. 109 (2009) 4054.[2] E.I. Vovk, E. Emmez, M. Erbudak, V.I. Bukhtiyarov, and E. Ozensoy, J. Phys. Chem. C 115(2011) 24256.[3] A. Trovarelli, Catal. Rev. 38,4 (1996) 439.69