MOF-74-M (M = Mn, Co, Ni, Zn, MnCo, MnNi, and MnZn) for Low-Temperature NH<sub>3</sub>-SCR and In Situ DRIFTS Study Reaction Mechanism
Shangzhi Xie, Qiuju Qin, Hao Liu, Lijian Jin, Xiaoling Wei, Jiaxing Liu, Xia Liu, Yinchao Yao, Lihui Dong, Bin Li
Abstract
Monometallic and bimetallic MOF-74-M (M = Mn, Co, Ni, Zn, MnCo, MnNi, and MnZn) catalysts were prepared by the solvothermal method for NH3-SCR. XRD, BET, SEM, and EDS-mapping tests indicate the successful synthesis of the MOF-74-M catalyst with uniform distribution of metal elements and large specific surface area, and the morphology is almost hexagonal. Adding Mn element to a single-metal catalyst can enhance activity, which is mainly because of the existence of various valence states of Mn so that it has excellent redox properties; the catalytic activity of water and sulfur resistance tests showed that the catalytic activity of MOF-74-M increases after adding a proper amount of SO2, mainly because of the increase in acidic sites. In situ DRIFTS results indicate that the low-temperature range of MOF-74-MnCo and MOF-74-Mn is dominated by the E–R mechanism and the high-temperature range is dominated by the L–H mechanism. The entire temperature range of MOF-74-Zn is dominated by the L–H mechanism.