Synergistic removal of nitrogen oxides (NOx) and particulate matter (PM) can be achieved using multifunctional catalytic membranes. In this work, CePO4 nanorods were loaded on the pore surfaces of SiC membranes to construct the CePO4/SiC-X catalytic membranes. The stacked nanorod structure of the CePO4 catalyst layer facilitates the diffusion of gases to the catalyst surface during reactions. Owing to the high specific surface area, rich surface acidity, and strong redox capacity, the CePO4/SiC-400 catalytic membrane exhibits the best ammonia-selective catalytic reduction (NH3–SCR) denitration activity, achieving >90% NO conversion at a temperature of 250–380 °C and negligible N2O byproduct. In addition, the CePO4/SiC-400 catalytic membrane demonstrates excellent H2O and SO2 resistance. The performance of dust filtration and simultaneous dust filtration and denitration at 250–350 °C proposed that the dust rejection efficiency reached more than 99% at various conditions, and the dust filtration process did not affect the NH3–SCR performance of the CePO4/SiC-400 catalytic membrane. From the above results, the CePO4/SiC-400 catalytic membrane presents a broad application prospect in the simultaneous dust removal and denitration of high-temperature flue gas.
Revealing the active species of the catalyst is conducive to the design of more efficient catalyst. Herein, we tried to demonstrate the roles of amorphous and crystalline structures on CePO 4 catalyst during selective catalytic reduction (SCR) of NO x by NH 3 . Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO 4 . Both amorphous and crystalline CePO 4 species on CePO- X samples can provide acid sites for NH 3 adsorption, but the former can provide more acid sites. The superior redox property of surface amorphous CePO 4 species contributes to its high NH 3 -SCR activity at low temperature, but it also leads to the decrease of high temperature (>350 °C) NH 3 -SCR activity due to the oxidation of NH 3 . In contrast, crystalline CePO 4 species shows high activity only at high temperature because of its poor redox property. Therefore, it can be inferred that amorphous and crystalline structures on CePO 4 catalyst can be the efficient active species of NH 3 -SCR at low and high temperature, respectively.
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