Promotional effect of Mn modification on DeNOx performance of Fe/nickel foam catalyst at low temperature.

Manganese (Mn)-modified ferric oxide/nickel foam (Fe/Ni) catalysts were prepared using Ni as a carrier, Fe and Mn as active components to study NH3-SCR of NOx at low temperature. The effects of different Fe loads and Mn-modified Fe/Ni catalysts on the DeNOx activity were investigated. Results show that when the amount of Fe is 10%, Fe/Ni catalyst has the highest NOx conversion. For the Mn-modified Fe/Ni catalysts, the NOx conversions firstly increase and then decrease with the Mn loading amount increasing. 3MnFe/Ni catalyst shows high NOx conversions, which reach 98.4-100% at 120-240 °C. The characterization analyses reveal that Mn-modified Fe/Ni catalysts increase the FeOx dispersion on Ni surface, improve significantly the valence ratio of the Fe3+/Fe2+, the content of lattice oxygen which promotes the catalyst storage and exchange oxygen capacity at low temperature, and the number of Brønsted active acid sites on the catalyst surface, and enhance the low-temperature redox capacity. These factors remarkably increase the NOx conversions at low temperature. Especially, 3Mn10Fe/Ni catalyst not only has excellent DeNOx activity but also has better water resistance. However, the anti-SO2 poisoning performance needs to be improved. To further analyze the reason why different catalysts show different DeNOx performance, the reaction kinetics was also explored.