Enhanced performance of iron-cerium NOx reduction catalysts by sulfuric acid treatment: The synergistic effect of surface acidity and redox capacity

Abstract

CeO2-based catalysts have raised extensive attention in selective catalytic reduction of NO with NH3 but the poor T90 operation window limits their industrial application. In present work, FeOx-CeO2 mixed oxides were prepared by a sol-gel method for NH3-SCR, and the effects of sulfuric acid treatment on the catalytic performance were systematically investigated. The results showed that sulfuric acid treatment significantly improved the high temperature activity. Compared to the FeOx-CeO2 sample, the T90 operation window of FeOx-CeO2-S was greatly broadened from 200−300 °C to 250−450 °C. Various characterizations demonstrated that sulfuric acid introduction increased redox capacity and also enhanced surface acidity. The synergistic effect of these two parameters was closely associated with the enhanced performance. Further investigations revealed that the sulfuric acid modification favored the formation of active intermediate species for N2 generation, while inhibited the formation of N2O and NOx, thus contributing to the high catalytic activity and N2 selectivity.