Effects of ferric and manganese precursors on catalytic activity of Fe-Mn/TiO 2 catalysts for selective reduction of NO

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RESEARCH ARTICLE

Effects of ferric and manganese precursors on catalytic activity of Fe-Mn/TiO2 catalysts for selective reduction of NO with ammonia at low temperature Huan Du 1,2 & Zhitao Han 1,2

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Qimeng Wang 1,2 & Yu Gao 1,2 & Cong Gao 1,2 & Jingming Dong 1,2 & Xinxiang Pan 1,2,3

Received: 3 December 2019 / Accepted: 8 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020

Abstract Fe-Mn/TiO2 catalysts were prepared through the wet impregnation process to selective catalytic reduction of NO by NH3 at low temperature, and series of experiments were conducted to investigate the effects of key precursors on their SCR performance. Ferric nitrate, ferrous sulfate, and ferrous chloride were chosen as Fe precursors while manganese nitrate, manganese acetate, and manganese chloride as Mn precursors. These precursors had been commonly used to prepare Fe-Mn/TiO2 catalysts by numerous researchers. The results showed that there were distinct differences in NO conversion efficiencies at low temperature of catalysts prepared with different precursors. Catalysts prepared with ferric nitrate and manganese nitrate precursors exhibited the best catalytic performance at low temperature, while three kinds of catalysts prepared with manganese chloride precursors exhibited significantly low catalytic activity. All catalysts were characterized by XRD, SEM, H2-TPR, NH3-TPD, and XPS. The results indicated that when the catalysts were prepared with manganese nitrate or manganese acetate as precursors, Mn4+ contents and Oβ/ (Oβ + Oα) ratios decreased in an order of ferric nitrate > ferrous sulfate > ferrous chloride, which was consistent with the change of catalytic activities of the corresponding catalysts at low temperature. It can be found that the excellent catalytic performance of Fe(A)-Mn(a)/TiO2 was ascribed to high redox property and enrichment of Mn4+species and surface chemical labile oxygen groups. Keywords Nitrogen oxides . Precursors . Selective catalytic reduction . Fe-Mn/TiO2 catalysts

Highlights • The effects of Fe and Mn precursors on NH3-SCR performance were investigated. • The catalyst prepared using ferric nitrate and manganese nitrate precursors exhibited the best catalytic activity at low temperature, while the catalysts prepared with chloride precursors exhibited much lower catalytic activities. • The choice of Fe and Mn precursors was crucial for preparing Fe-Mn/ TiO2 catalysts, which would probably affect the redox property, Mn4+ content, the surface chemisorbed labile oxygen content, and the dispersion of active species over support. Responsible Editor: Vítor Pais Vilar Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-10073-y) contains supplementary material, which is available to authorized users. * Zhitao Han [email protected] * Xinxiang Pan [email protected] 1

Marine Engineering College, Dalian Maritime University, No.1, Linghai Road, Dalian 116026, China

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Liaoning Research Center for Marine Internal Combustion Engine Energy-Savi