The effect of dopants (Fe, Al) on the low-temperature activity and SO2 tolerance in solvothermally synthesized MnOx NH3-SCR catalysts.

[Display omitted] • Fe/Al-doped MnO x catalysts synthesized by solvothermal method. • Fe/Al doping improved the SCR activity and N 2 selectivity of MnO x catalysts. • Improved redox capability of MnFeO x enhanced LT SCR activity and H 2 O/SO 2 resistance. • Thermal regeneration weakened metal-sulfate interactions in poisoned MnFeO x. • MnFeO x exhibited higher thermal regenerability than MnAlO x. Fe-doped MnO x catalyst prepared by a preferred solvothermal method displayed noticeably better low-temperature (LT) NH 3 -SCR performance and water stability than an analogously prepared Al-doped MnO x catalyst. The SCR activity of both catalysts decreased markedly when exposed to SO 2 , but the resultant MnFeO x -S catalyst retained higher LT activity than MnAlO x -S and recovered significantly more of its original activity after thermal regeneration (400 °C). Comprehensive characterization confirmed that the deactivation of the catalysts was governed by formation of stable metal sulfates, which only decomposed to a minor extent upon thermal treatment although Al doping lowered the thermal stability of the adsorbed sulfur species. Additionally, Fe doping was found to facilitate electron transfer between Mn and Fe ions and weaken the interaction between active sites and deposited sulfates during the heating procedure, which promoted re-oxidation of Mn2+ to catalytically active Mn3+/Mn4+. Altogether, the altered redox properties resulted in improved LT SCR performance, enhanced water stability, higher SO 2 tolerance and superior regeneration of the MnFeO x catalyst. [ABSTRACT FROM AUTHOR]