Simultaneous removal of SO2 and NO with OH from the catalytic decomposition of H2O2 over Fe-Mo mixed oxides

Abstract In this paper, the simultaneous removal of SO2 and NOx catalyzed by Fe-Mo mixed oxides at varying Mo/Fe atomic ratios was reported for the first time with the aim of reducing H2O2 consumption and elucidating the roles of Fe and Mo species in the catalytic process. Fe-Mo mixed oxides with varying Mo/Fe atomic ratios were synthesized and the catalytic performances were systematically studied. The catalyst with Mo/Fe atomic ratio of 2.0 exhibited the highest activity, with which removal efficiencies of 89.4 % for NOx and 100 % for SO2 can be attained at extremely low H2O2 dosage. Products analysis revealed that SO2 was mainly removed via wet scrubber, while the adequate oxidation resulting from OH radicals was the prerequisite for NOx removal. The redox pair of Fe2+/Fe3+ played a significant role in decomposing H2O2, while Mo species had double effect on catalytic activity. Higher Mo content resulted in abundant oxygen vacancies and stronger surface acidity, which favored OH formation. However, the excessive Mo content involved severe surface Mo enrichment and remarkably reduced the active sites of Fe species. The H2O2/Fe-Mo catalyst system showed excellent stability and had a promising prospect for simultaneously removing SO2 and NOx in coal-fired flue gas.