Influence of Fe‐modified Mn–Ce–Fe–Co–Ox/P84 catalytic filter materials for low‐temperature NO removal synergistic Hg0oxidation

Abstract

AbstractA series of Mn–Ce–Fe–Co–Ox/P84 (polyimide) catalytic filter materials by in situ method (ISM) were investigated for the low‐temperature catalytic activities for NO and elemental mercury Hg0in the simulated flue fixed‐bed system, especially under mixed atmosphere conditions with water and sulfur. The influence of Fe and Co doping ratio, Fe of loading sequence, and the types of precursors are systematically investigated under 8% H2O and 75 ppm SO2atmosphere. Results showed that the toxic effects of H2O and SO2on the catalytic filter materials were obvious. When using Mn–Ce–Fe–Co–Ox/P84 catalytic filter materials (Mn/Ce/Fe/Co = 4:5:0.5:0.5, in mol), the NO reduction and Hg0oxidation decreased from 95.0% to 40.0% and 55%, respectively. As the molar ratio of Fe/Co increased, the anti‐sulfur and water resistance activity of catalytic filter materials showed a trend of first increasing and then decreasing. Active components of Mn–Ce–Fe–Co–Ox/P84 (Mn/Ce/Fe/Co = 4:5:1.25:1 in mol) could achieve 81.0% of NO reduction and 79.2% Hg0oxidation simultaneously. As the molar ratio of Fe/Co increased, the NOxsynergistic Hg0conversion efficiency of the catalytic filter materials was first promoted and then suppressed. Comparing the order of Fe impregnation and the types of Fe precursors revealed that using Fe(NO3)3to generate Fe2O3was more active than directly using Fe2O3at 170°C to 260°C. Electron transfer between Mn, Ce and Fe increases the high ratio of Mn4+/(Mn4++Mn3+) and Ce3+/(Ce3++Ce4+) which may enhance the sulphur and water resistance of the catalytic filter materials.