ZrO₂ Modified MnO_x/Attapulgite Catalysts for NH₃-SCR of NO at Low Temperature

Abstract

A series of Zirconium modified MnO_x/Attapulgite (aZr–Mn/ATP) catalysts were synthesized by sol–gel method and evaluated for their performance in the low-temperature NH₃-SCR of NO and resistance to sulfur dioxide (SO₂). It was found that the NO conversion of Mn/ATP catalyst significantly improved after adding Zr. Among the catalysts investigated, the 4%Zr–Mn/ATP catalyst exhibited the highest catalytic activity, 96% NO conversion at 200°C, almost 100% N₂ selectivity in the whole test temperature range and good resistance to SO₂. The properties of catalysts were characterized by XRD, FTIR spectra, SEM and N₂ adsorption. In the catalyst, ATP is the support which supplies high surface areas, manganese (Mn₃O₄ and MnO₂) as the main active component plays an important role for NO reduction and zirconium (ZrO₂) acts as the auxiliary catalyst which can improve the diffusion of Mn, boost the low-temperature reduction performance and enhance the N₂ selectivity of the catalyst.