Synthesis of Both Powdered and Preformed MnO_x–CeO₂–Al₂O₃ Catalysts by Self-Propagating High-Temperature Synthesis for the Selective Catalytic Reduction of NO_x with NH₃

摘要

MnO_(x) –CeO_(2)–Al_(2)O_(3) powdered and preformed catalysts were prepared through self-propagating high-temperature synthesis (SHS) and impregnation methods. Compared to the traditional impregnation method, the SHS method has a shorter catalyst preparation cycle and simpler preparation process. The characterization results showed that mixed crystals of cerium, aluminum, and manganese oxides were formed through the SHS method, the binding energy of Mn~(4+) increased, and the active components were distributed uniformly. The MnO_(x) –CeO_(2)–Al_(2)O_(3) powdered catalyst had an extensive pore structure, with a Brunauer–Emmett–Teller surface area of approximately 136 m~(2)/g, a pore volume of approximately 0.17 cm~(3)/g, and an average pore diameter of approximately 5.1 nm. Furthermore, the MnO_(x) –CeO_(2)–Al_(2)O_(3) powdered catalyst achieved a NO_(x) conversion higher than 80% at 100–250 °C. Coating liquids with identical metal-ion concentrations were prepared using the catalysts, and the preformed catalyst obtained through the SHS method had a higher loading capacity after one coating. The MnO_(x) –CeO_(2)–Al_(2)O_(3) preformed catalyst achieved a NO_(x) conversion higher than 70% at 200–350 °C.