Construction of fluffy MnFe nanoparticles and their synergistic catalysis for selective catalytic reduction reaction at low temperature

Abstract

Mn-based catalysts had favorable low temperature SCR performance but it was restricted its practical application due to easy deactivation. Different proportions of Fe species were doped into Mn-MOFs as a precursor by a simple one-pot solvothermal method. A series of MnOx, Mn4FeOx, MnFeOx and MnFe4Ox catalysts with different structures were obtained by calcining under air. MnFeOx showed better catalytic activity and water resistance at low temperature. The NO conversion was 96% at 200 °C and kept above 85% in the range of 120–280 °C. Through a series of characterizations, it was found that manganese and iron species were highly dispersed in the MnFeOx catalyst, which was a vital factor for SCR reaction. Moreover, the MnFeOx catalyst not only possessed a large specific surface area and pore volume but also had a better reduction ability and abundant oxygen vacancies to adsorb and activate the reaction gases. Therefore, the catalyst possessed a satisfactory catalytic performance. More importantly, charging transfer between active manganese species and iron species in MnFeOx catalyst could effectively inhibit H2O poisoning and improve the stability of the catalyst. The results of in situ DRIFTs experiments showed that the low temperature NH3-SCR reaction of MnFeOx catalyst followed L-H mechanism. The effects of Fe doping content on the crystal structure of active species and SCR performance of manganese-based catalysts were revealed.