Low-temperature SCR of NO with NH3 over biomass char supported highly dispersed Mn[sbnd]Ce mixed oxides

Abstract

Series of catalysts with MnCe mixed oxides loaded onto biomass char (BC) modified by nitric acid were prepared via impregnation method. And these catalysts were used for the selective catalytic reduction (SCR) of NO with NH3. MnCe (7:3)/BC catalysts with loading 6% (mass ratio) MnCe oxides showed the best NO conversion ratio of 99.2% at 175 °C. The changes of the microstructure, phase composition, metal valence state and functional groups were investigated through SEM, BET, XRD, XPS and FT-IR. It showed that nitric acid modification could increase surface acidic functional groups of biomass char. And surface functional groups on BC could increase NH3 and NO adsorption capacity. In the denitration process, oxygen was transferred from CeO2 to Mn2O3, which could promote the cyclic catalytic reaction rate, then significantly enhanced the NO conversion in the MnCe/BC catalysts. Based on the experimental results and theoretical analysis, the synergetic mechanism model of surface functional groups on the surface of BC, Mn and Ce on the catalysts was set up.