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

Abstract

To realize the efficient denitrification of low-temperature (<150 °C) flue gas in nonelectric industries, the most promising strategy is to develop NH 3 selective catalytic reduction (NH 3 −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 FeMnO x 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 FeMnSmO x 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 FeMnSmO x , thus promoting the low-temperature NH 3 −SCR activity. NH 3 −SCR reaction on FeMnSmO x followed the "NOassisted NH 4 NO 3 pathway", in which gaseous NO would assist the reduction and decomposition of NH 4 NO 3 .

A Novel MnOx–MoOx Codoped Iron-Based Catalyst for NH3-SCR with Superior Catalytic Activity over a Wide Temperature Range

“…We investigated the redox characteristics of the FeO x , MF, and MFMo 4 catalysts by H 2 -TPR, and the outcomes are plotted in Figure . For the FeO x catalyst, three reduction peaks were observed near 335, 560, and 855 °C, corresponding to the reduction sequence of Fe 2 O 3 → Fe 3 O 4 → FeO → Fe. , The reduction peaks of the MF and MFMo 4 catalysts exhibited similarities. For the MF catalyst, reduction peaks appearing at 227, 297, and 411 °C were due to the reduction of MnO 2 → Mn 2 O 3 , Mn 2 O 3 → Mn 3 O 4 , and Mn 3 O 4 → MnO.…”