Optimization of Robust FeMnSmOx Catalyst for Low-Temperature (<150 °C) NH3–SCR of NOx

To realize the efficient denitrification of low-temperature (<150 °C) flue gas in nonelectric industries, the most promising strategy is to develop NH3 selective catalytic reduction (NH3–SCR) catalysts with superior low-temperature activity. Conversely, the low working temperature offered great flexibility for tuning the calcination temperature during catalyst manufacturing. Herein, starting with the Sm-doped FeMnOx catalyst, an easy but practical strategy of calcination temperature regulation was proposed. With the increase in the calcination temperature from 300 to 600 °C, the low-temperature activity of FeMnSmOx increased first and then decreased, and 500 °C was the optimal calcination temperature. Detailed characterizations revealed that the calcination at 500 °C could better facilitate the formation of more weak acid sites and enhance the redox properties of FeMnSmOx, thus promoting the low-temperature NH3–SCR activity. NH3–SCR reaction on FeMnSmOx followed the "NO-assisted NH4NO3 pathway", in which gaseous NO would assist the reduction and decomposition of NH4NO3.