Roles of Promoters in V<SUB>2</SUB>O<SUB>5</SUB>/TiO<SUB>2</SUB> Catalysts for Selective Catalytic Reduction of NOx with NH<SUB>3</SUB>: Effect of Order of Impregnation

Abstract

Recently, various promoters for commercial selective catalytic reduction (SCR) catalysts are used to improve DeNOx activity at low temperature. We aimed at finding the optimum condition to prepare V2O5/TiO2 catalyst by changing promoters (W, Ce, Zr and Mn), not only for improving SCR reactivity, but also for reducing N2O formation at high temperature. In addition, we changed the order of impregnation between promoter and vanadium precursors on TiO2 support and observed its effect on activity and N2O selectivity. We utilized various analytical techniques, such as N2 adsorption-desorption, X-ray Diffraction (XRD), Raman spectroscopy, UV-visible Diffuse Reflectance Spectroscopy (UV-vis DRS) and Temperature Programmed Reduction with hydrogen (H2-TPR) to investigate the physicochemical properties of V2O5/TiO2 catalysts. It was found that W and Ce added V2O5/TiO2 catalysts showed the most active DeNOx properties at low temperature. Additionally, the difference in impregnation order affected the SCR activity. The superiority of low temperature activity of the vanadium firstly added catalysts (W or Ce/V/TiO2) is attributed to the formation of more polymerized V2O5 on the sample.

Characterization and SCR Performance of Nano-Structured Iron-Manganese Oxides: Effect of Annealing Temperature

“…Among these catalysts, V 2 O 5 /TiO 2 in combination with MoO 3 and WO 3 has been commercialized in consequence of its high catalytic reactivity, including NO conversion, N 2 selectivity and resistance to sulfur poisoning, and mechanical strength. In view of high reaction temperature and environmental toxicity of vanadium species (Liu and He, 2010;Liu et al, 2011b;Ma et al, 2011;Youn et al, 2016), vanadium-free catalysts attracted much attention including M-zeolite catalysts (M-Fe, Cu, Mn, Mo) (Pérez-RamıŔez et al, 2004;Yoshida et al, 2004;Liu et al, 2011a;Ochońska et al, 2012;Schuricht and Reschetilowski, 2012;Mejri et al, 2016) and metal oxides catalysts (Fe, Mn, Cu, Ce, Cr, etc. ) (Kato et al, 1981;Baksh et al, 1992;Kapteijn et al, 1994;Chen et al, 1995;Schneider et al, 1995;Zhu et al, 1999;Eigenmann et al, 2006;Min et al, 2007;Xu et al, 2008;Liu et al, 2013a;Shin et al, 2016).…”

Review on the latest developments in modified vanadium-titanium-based SCR catalysts

“…Their denitri ication ef iciencies were ˂60% at 200 °C [103]. In addi-tion, although loading on TiO2 can improve the SCR activity at low temperatures (150-250 °C) [104,105] , when added into V2O5/TiO2 as promoter, MnOx had a negative effect on the SCR performance and slightly reduced N2O generation [92].…”

“…Owing to the strong redox ability and oxygen storage capacity of CeO2, ceria-based catalysts have been attracting increasing attention worldwide [88][89][90]. Ce can significantly increase both the low-temperature deNOx efficiency and reaction rate of vanadium-titanium-based SCR catalysts when doped into the carrier [91] or loaded as an additive [87,92]. Current studies generally believe that Ce and V may work synergistically.…”

“…Ce 3+ species would cause charge imbalance, vacant sites, and unsaturated chemical bonds, which increase the amount of chemisorbed oxygen and NO oxidation. Rich surface acidity, strong redox properties, and active intermediate species are the main reasons for the high deNOx activity of Ce-doped SCR catalysts [87,[91][92][93][94][95][96][97]. Furthermore, Zhang et al [94,95] and Li et al [96] respectively chose TiO2-ZrO2 and TiO2-carbon nanotubes (CNT) to replace raw TiO2 as the carrier for Ce-doping catalysts.…”

The Characterization and SCR Performance of Mn-Containing α-Fe2O3 Derived from the Decomposition of Siderite

“…For the catalysts, TiO 2 -supported vanadium-based catalysts such as V 2 O 5 −WO 3 /TiO 2 catalysts are widely used due to their advantages, including high NO conversion, N 2 selectivity, resistance to sulfur toxicity, and strong mechanical strength [10][11][12][13]. However, considering the high reaction temperature and environmental toxicity of vanadium-based catalysts [14][15][16], vanadium-free catalysts like metal oxides (Fe, Mn, Cu, Ce) have received more and more attention [17][18][19].…”