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Selective catalytic reduction of NOx by ammonia (NH3‐SCR) was affected by HCl, which was widely present in industrial flue gas. In this study, the SCR performances over MOx‐WO3/TiO2 (MW/Ti, M=Mn, Ce and V) catalysts after HCl treatment were investigated. It was found that HCl poisoning showed inhibition and promotion in NOx conversion over MnW/Ti and CeW/Ti catalysts, respectively. While the SCR activity over VW/Ti catalyst was hardly affected by HCl. Over MnW/Ti catalyst, the rupture of the Mn−O bond by the strong Mn−Cl binding induced the formation of amorphous MnCl2 species. This Cl‐containing species with Mn in a low oxidation state exhibited poorer redox ability and NO activation, resulting in a decrease in low‐temperature SCR activity. However, instead of directly affecting the CeOx and VOx sites, gaseous HCl reacted with NH3 to form NH4Cl species on the surface of CeW/Ti and VW/Ti catalysts. As a result, the SCR activity of VW/Ti catalyst was scarcely influenced by HCl, taking the unchanged redox ability and NH3 adsorption. With a further accumulation of NH4Cl on CeW/Ti catalyst, the NOx conversion at low temperature was evidently enhanced due to the promotion in NO‐to‐NO2 conversion (Fast‐SCR). [ABSTRACT FROM AUTHOR]

Selective catalytic reduction of NOx by ammonia (NH3‐SCR) was affected by HCl, which was widely present in industrial flue gas. In this study, the SCR performances over MOx‐WO3/TiO2 (MW/Ti, M=Mn, Ce and V) catalysts after HCl treatment were investigated. It was found that HCl poisoning showed inhibition and promotion in NOx conversion over MnW/Ti and CeW/Ti catalysts, respectively. While the SCR activity over VW/Ti catalyst was hardly affected by HCl. Over MnW/Ti catalyst, the rupture of the Mn−O bond by the strong Mn−Cl binding induced the formation of amorphous MnCl2 species. This Cl‐containing species with Mn in a low oxidation state exhibited poorer redox ability and NO activation, resulting in a decrease in low‐temperature SCR activity. However, instead of directly affecting the CeOx and VOx sites, gaseous HCl reacted with NH3 to form NH4Cl species on the surface of CeW/Ti and VW/Ti catalysts. As a result, the SCR activity of VW/Ti catalyst was scarcely influenced by HCl, taking the unchanged redox ability and NH3 adsorption. With a further accumulation of NH4Cl on CeW/Ti catalyst, the NOx conversion at low temperature was evidently enhanced due to the promotion in NO‐to‐NO2 conversion (Fast‐SCR). [ABSTRACT FROM AUTHOR]

Selective catalytic reduction of nitrogen oxides (NOx) with C3H6 (C3H6‐SCR) was investigated over NiO catalysts supported on different metal‐oxides. A NiAlOx mixed oxide phase was formed over NiO/γ‐Al2O3 catalyst, inducing an immediate interaction between NiOx and AlOx species. Such interaction resulted in a charge transfer from Ni to Al site and the formation of Ni species in high oxidation state. In comparison to other NiO‐loaded catalysts, NiO/γ‐Al2O3 catalyst exhibited the highest NOx conversion at temperature higher than 450 °C, but a poor C3H6 oxidation activity due to the decreased nucleophilicity for surface oxygen species. By temperature‐programed NO oxidation, it is indicated that nitrate species were rapidly formed and stably maintained at high temperature over NiO/γ‐Al2O3 catalyst. In situ transient reactions further verified the Langmuir–Hinshelwood mechanism for C3H6‐SCR, where both gaseous NO and C3H6 were adsorbed and activated on catalyst surface and reacted to generate N2. Due to the strong metal‐support interaction over NiO/γ‐Al2O3 catalyst, both nitrate and CxHyOz intermediates were well preserved to attain high C3H6‐SCR activity. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction of nitrogen oxides (NOx) with C3H6 (C3H6‐SCR) was investigated over NiO catalysts supported on different metal‐oxides. A NiAlOx mixed oxide phase was formed over NiO/γ‐Al2O3 catalyst, inducing an immediate interaction between NiOx and AlOx species. Such interaction resulted in a charge transfer from Ni to Al site and the formation of Ni species in high oxidation state. In comparison to other NiO‐loaded catalysts, NiO/γ‐Al2O3 catalyst exhibited the highest NOx conversion at temperature higher than 450 °C, but a poor C3H6 oxidation activity due to the decreased nucleophilicity for surface oxygen species. By temperature‐programed NO oxidation, it is indicated that nitrate species were rapidly formed and stably maintained at high temperature over NiO/γ‐Al2O3 catalyst. In situ transient reactions further verified the Langmuir–Hinshelwood mechanism for C3H6‐SCR, where both gaseous NO and C3H6 were adsorbed and activated on catalyst surface and reacted to generate N2. Due to the strong metal‐support interaction over NiO/γ‐Al2O3 catalyst, both nitrate and CxHyOz intermediates were well preserved to attain high C3H6‐SCR activity. [ABSTRACT FROM AUTHOR]