In situ construction of heteroatom F-doped Mn3O4 spinel catalysts with robust activity and SO2 resistance for NH3-SCR at low temperature

Abstract

Herein, we propose a novel in situ construction method of F-doped Mn3O4 catalysts through a crystallization-pyrolysis-oxidation strategy. The F-Mn3O4-3 % exhibits a NO conversion above 90 % from 150° to 310°C at an ultra-high GHSV of 400,000 h−1. The SO2 resistance is also significantly improved compared to pure Mn3O4. Doping of Mn3O4 with F increases the surface acidity and tunes the electronic properties of the catalysts. The increase of acid sites not only facilitates the adsorption of NH3 species, thereby improving NH3-SCR activity, but also inhibits SO2 adsorption on the catalyst surface. The electron conduction between SO2 and Mn3+ can also be effectively inhibited after F replaces O, resulting in the F-doped Mn3O4 catalysts can selectively oxidizing NO to NO2 rather than oxidizing SO2 to SO3, thereby causing the decrease of sulfate species. Our work provides a novel idea for the design of SCR catalysts with high activity and SO2 resistance.