Physico-Chemical Property and Catalytic Activity of a CeO<SUB>2</SUB>-Doped MnO<I><SUB>x</SUB></I>–TiO<SUB>2</SUB> Catalyst with SO<SUB>2</SUB> Resistance for Low-Temperature NH<SUB>3</SUB>-SCR of NO<I><SUB>x</SUB></I>

Abstract

The effects of CeO2 addition on the catalytic activity and the SO2 resistance of CeO2-doped MnO(x)-TiO2 catalysts were investigated for the low-temperature selective catalytic reduction (SCR) with NH3 of NO(x) emissions in marine applications. The most active catalyst was obtained from 30 wt% CeO2-MnO(x)-TiO2 catalyst in the whole temperature range of 100-300 degrees C at a low gas hourly space velocity (GHSV) of 10,000 h(-)1, and its de-NO(x) efficiency was higher than 90% over 250 degrees C. The enhanced catalytic activity may contribute to the dispersion state and catalytic acidity on the catalyst surface, and the highly dispersed Mn and Ce on the nano-scaled TiO2 catalyst affects the increase of Lewis and Brønsted acid sites. A CeO2-rich additive on MnO(x)-TiO2 could provide stronger catalytic acid sites, associated with NH3 adsorption and the SCR performance. As the results of sulfur resistance in flue gas that contains SO2, the de-NO(x) efficiency of MnO(x)-TiO2 decreased by 15% over 200 degrees C, whereas that of 30 wt% ceria-doped catalyst increased by 14-21% over 150 degrees C. The high SO2 resistance of CeO2-MnO(x)-TiO2 catalysts that resulted from the addition of ceria suppressed the formation of Mn sulfate species, which led to deactivation on the surface of nano-catalyst.

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

“…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).…”

Recent advances and perspectives in the resistance of SO2 and H2O of cerium-based catalysts for NOx selective catalytic reduction with ammonia

“…In general, W, 40 Mo, 95 Nb, 118 Cu, 75,119 Mn, 120 Fe, 121,122 Co, Ag, Cr, Ni, Sn 76,123 and other metallic elements have excellent anti-H 2 O performance in selective catalytic reduction of NO by NH 3 . Because the existence of H 2 O can facilitate the formation of hydroxyl groups on the cerium-based catalyst surface, decreasing the adsorption capacity of NH 3 and NO and the number/intensity of the active sites will be restrained.…”