Inspecting Promotive Functions of Antimony Oxides for NH3-Assisted Selective Catalytic NOX Reduction

Abstract

It is widely accepted that Sb oxide promotes redox cycling feature and SO₂ resistance of a catalyst utilized for selective catalytic NO_X reduction (SCR) at low temperatures (≤300 ℃). However, promotive roles of Sb oxide have never been explored with the alteration of its crystal phases, which can be crucial to direct the overall acidic/redox characteristics and SCR performance of a catalyst along with its SO₂ tolerance. In this regard, while implementing TiO2-supported Mn oxide (Mn) as a model catalyst, we successfully isolated Sb₂O₃ and Sb₂O₅ on Mn using wet impregnation and precipitation protocols, leading to produce Mn-Sb-I and Mn- Sb-P, respectively. The resulting catalysts were verified to have comparable acidic properties, yet, exhibit distinct redox traits, as evidenced by the greatest quantity of labile oxygens for Mn-Sb-I (Sb₂O₃) compared to Mn and Mn-Sb-P (Sb₂O₅). This leads to significant enhancement of SCR performance and SO₂ resistance for Mn-Sb-I over the others.