Influence of ceria modification on the properties of TiO2–ZrO2 supported V2O5 catalysts for selective catalytic reduction of NO by NH3

Abstract

TiO2–ZrO2 (hereafter denoted as Ti–Zr) supported V2O5 catalysts with different loadings of CeO2 were synthesized, and their physicochemical properties were characterized by Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), in situ Fourier transform infrared spectroscopy (in situ FT-IR) and temperature-programmed reduction (TPR). Their catalytic activities toward the NOx reduction reaction with NH3 were tested. We found that with the addition of CeO2, more NO was removed in a wide temperature range of 220–500°C. As the CeO2 content was increased from 10% to 20% (i.e., the molar ratio of Ce to Ti–Zr), NO conversion increased significantly; after that, increasing CeO2 content, however, decreased NO conversion. In particular, the addition of CeO2 to V2O5/Ti–Zr suppressed the coke deposition and rendered a stable and high catalytic activity. The characterization results indicated that: (1) the deposited vanadium and cerium oxides were highly dispersed over the Ti–Zr support, and in addition to ZrV2O7, a common binary compound observed in V2O5/Ti–Zr, CeVO4 and Ce3ZrO8 was formed upon increasing CeO2 content; (2) the introduction of CeO2 to V2O5/Ti–Zr sample promoted the redox ability of the resulting catalysts; and (3) the Ce-containing catalysts possessed the greater amount of surface acidic and active intermediate.