Correlation between the physicochemical properties and catalytic performances of CexSn1–xO2 mixed oxides for NO reduction by CO

Abstract

A series of CexSn1–xO2 mixed oxides and single oxides (CeO2 and SnO2) were prepared by inverse co-precipitation method and calcined at 450 and 750°C to investigate the correlation between the physicochemical properties and catalytic performances of these catalysts for NO reduction by CO. The obtained samples were characterized in detail by means of XRD, UV-Raman, N2-physisorption, H2-TPR, XPS, and in situ DRIFTS technologies. Moreover, the catalytic performances of these samples were evaluated through NO reduction by CO model reaction. These results indicate that the incorporation of Sn4+ into the lattice of CeO2 can result in the decrease of crystallite size, the increase of lattice strain and the improvement of reduction behavior, which are beneficial to the enhancement of catalytic performance. Furthermore, the catalyst with the optimal mole ratio (Ce:Sn=2:1) exhibits the best catalytic performance for NO reduction by CO model reaction, because that more catalytic domains (CD, -Ce3+-□-Sn2+- species) can be generated in the reaction process due to the enhancement of reduction behavior and the formation of uniform solid solution without crystalline SnO2 blocking the active sites. Finally, in order to explore the significant role of catalytic domain (CD, -Ce3+-□-Sn2+- species) in NO reduction by CO model reaction, a possible reaction mechanism is tentatively proposed.