Novel manganese-based assembled nanocatalyst with “nitrous oxide filter” for efficient NH3-SCR in wide low-temperature window: Optimization, design and mechanism

• Introduction of WO 3 promoted N 2 selectivity and broadened temperature window. • Novel assembly strategy “ acidity u & redox d ” balanced activity and N 2 selectivity. • Doping WO 3 changed the reaction mechanism that promoted NH 3 /inhibited NO adsorption. • Doping rare earth elements improved redox ability and low temperature activity. • The modified acid zeolite-like montmorillonite is an efficient SCR catalyst support. It is still a challenge for de-NO x catalysts to have high activity and N 2 selectivity in a wide low-temperature operating temperature window. In this work, we used layered zeolite-like montmorillonite as the support and then obtained a composite catalyst with satisfactory NO x conversion and excellent N 2 selectivity in the temperature range of 100–300 °C with the method of pillaring modification, active component doping, and catalyst assembly. It has been proved that doping rare earth elements can improve the redox ability of the catalyst, and WO 3 modification can enhance the acidity of the catalyst. The redox ability and the surface acidity of the catalyst system were balanced by assembling the WO 3 -modified catalyst and the WO 3 -unmodified catalyst. Besides, we found the composite Pr 1 Mn 9 /Fe 7 Ti 3 -W u -mmt catalyst had the best catalytic activity and N 2 selectivity only when the reaction gas first passed through the catalyst modified by WO 3 , in which the WO 3 -modified catalyst acted as the role of nitrous oxide filter. What’s more, according to the results of in situ DRIFTS, it can be indicated that the montmorillonite-supported catalysts in this work followed the L-H mechanism and E-R mechanism; while the E-R mechanism was dominant when the catalyst was modified by WO 3 . The results in present work indicate that the novel strategy of assembling catalysts is practicable to obtain an efficient de-NO x catalyst with a wide low-temperature operating temperature window, high NO x conversion, and high N 2 selectivity. Furthermore, the novel assembly strategy of tandem catalysis with stronger acidity sites and redox sites in turn “ acidity u & redox d ” can be extended to other SCR catalytic systems.