Sulfur poisoning resistant mesoporous Mn-base catalyst for low-temperature SCR of NO with NH3

Abstract

Mesoporous MnO2-Fe2O3-CeO2-TiO2 was prepared with sol–gel method and demonstrated to have good low-temperature activity and sulfur-poisoning resistance for selective catalytic reduction (SCR) of NO with NH3 in SO2-containing gases. In comparison with this, the catalyst with the same composition but made according to the conventional impregnation method exhibited obviously lower SO2-poisoning resistance and selectivity to the formation of N2 in the SCR reactions. FTIR analysis of the spent catalysts after SCR reactions for 16h and 60h in a SO2-contaning gas demonstrated that there was little difference in the amount of deposited ammonium sulfate over the mesoporous catalyst between the two cases. The mesopore channels existing in the mesoporous catalyst enabled probably a dynamic balance between the formation and decomposition of ammonium sulfate in SCR reactions. This concern was justified through comparing the N2 adsorptions and XPS spectra for the catalysts made with the impregnation and sol–gel methods. The article clarified as well the facilitation effects of introducing Ce and Fe into the mesoporous catalyst on activity, selectivity and SO2-poisoning resistance.