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Ceria-based solid solutions were synthesized and used as supports to prepare MnO x /Ce 0.8 Ti 0.2 O 2 and MnO x /Ce 0.8 Sn 0.2 O 2 catalysts (Mn/CeTi and Mn/CeSn) for low temperature selective catalytic reduction of NO by NH 3 . The effects of Ti or Sn doping on the catalytic performance of MnO x /CeO 2 catalyst were investigated. Experimental results show that doping of Ti or Sn increases the NO removal efficiency of MnO x /CeO 2 . The NO conversion of Mn/CeTi catalyst is more than 90% at temperature window of 175–300 °C under a gas hour space velocity of 60,000 mL g −1 h −1 . Modified catalysts are also found to exhibit greatly improved resistance to sulfur-poisoning. Characterization results indicate that doping of Ti or Sn brings about catalysts with higher BET surface area, enhanced oxygen storage capacity and increased surface acidity. X-ray photoelectron spectroscopy (XPS) analysis of spent catalysts following SCR reaction in the presence of SO 2 verify that the loss of surface Mn species was inhibited by doping of Ti, which contributes to extend the sulfur durability. The SCR activity is considered as well to be promoted by the dual redox cycles in Mn/CeTi (Mn 4+ + Ce 3+ ↔ Mn 3+ + Ce 4+ , Ce 4+ + Ti 3+ ↔ Ce 3+ + Ti 4+ ) and Mn/CeSn (Mn 4+ + Ce 3+ ↔ Mn 3+ + Ce 4+ , 2Ce 4+ + Sn 2+ ↔ 2Ce 3+ + Sn 4+ ) catalysts. [ABSTRACT FROM AUTHOR]

Abstract: High surface area Ti0.5Sn0.5O2 mixed oxide with rutile phase was prepared by a coprecipitation method. The surface area of Ti0.5Sn0.5O2 sample is 76.7m2 g−1, and VO x /Ti0.5Sn0.5O2 catalysts were prepared using the mixed oxide as support. Characterizations using XRD, FT-IR, LRS, EPR, UV–vis, and TEM demonstrated that vanadium oxide species are highly dispersed on the surface of Ti0.5Sn0.5O2 support when the loading amount of vanadium oxide is ≤1.5mmolV/100m2 Ti0.5Sn0.5O2. The dispersed vanadium oxide species form epitaxial-growth layer on the support. In situ FT-IR (NH3 adsorption), combined with NH3-TPD, indicate that the catalyst with vanadium loading amount of 1.5mmolV/100m2 Ti0.5Sn0.5O2, which equals to the dispersion capability, possesses a maximum amount of Brønsted acid sites. The 1.5V/Ti0.5Sn0.5O2 catalyst exhibits the best catalytic performance and good resistance to water vapor poison for the “NO+NH3 +O2” reaction, indicating that surface dispersed polymeric vanadium oxide species are the primary active species. A possible reaction mechanism is proposed on the basis of in situ FT-IR results. [Copyright &y& Elsevier]