The effects of manganese precursors on Mn-based/TiO2 catalysts for catalytic reduction of NO with NH3

Abstract

Manganese acetate (MnAc) and manganese nitrate (MnN) were employed as precursors for the preparation of Mn(Ac)/TiO2, Mn (N)/TiO2, Mn(Ac)-Ce/TiO2, and Mn(N)-Ce/TiO2 by impregnation. These complexes were used as catalysts in the low-temperature selective catalytic reduction of NO with NH3. The influence of manganese precursors on catalyst characteristics, the reduction activity, and the stability of the catalysts to poisoning by H2O and SO2 were studied. Experiments showed that Mn(N) produced MnO2 with large grain sizes in Mn(N)/TiO2 catalyst. On the contrary, Mn(Ac) led to highly dispersed and amorphous Mn2O3 in Mn (Ac)/TiO2 catalyst, which had better catalytic activity and stability to SO2 at low temperatures. The doping of cerium reduced the differences in catalytic performance between the catalysts derived from different Mn precursors. Implications: Developing catalyst for selective catalytic reduction (SCR) of NOx from stationary sources at low reaction temperature is an attractive and key area of alternative process for existing SCR technology due to economical and environmental reasons. Manganese-based catalysts were proven very active at low temperature. In this paper, comparative studies were conducted on how manganese precursors were affecting the properties of resultant Mn-based/TiO2 catalysts. Different precursors could lead to different grain size of active components, manganese oxide dispersion, and surface phase state of Mn/TiO2 catalyst, whereas these influences are reduced with the doping of cerium oxides into Mn/TiO2. © 2012 A&WMA.