Low-Temperature NH(3)-SCR over Hierarchical MnO(x) Supported on Montmorillonite Prepared by Different Methods

[Image: see text] Hierarchical MnO(x) pillared or supported on montmorillonite were prepared by three methods, i.e., impregnation (IM), chemical precipitation (CP), and in situ deposition (SP). The catalysts were characterized by low-temperature N(2) adsorption (BET), XRD, XPS, SEM, TEM, H(2)-TPR, NH(3)-TPD, NO-TPD, TPSR, in situ DRIFTS, and evaluation of catalytic performance for NH(3)-SCR. The best catalytic performance was obtained for catalysts prepared by SP in terms of activity and selectivity, obtaining >90% NO conversion with >95% selectivity to N(2) in 100–300 °C and GHSV of 70,000 h(–1). Compared to IM and CP, SP greatly simplified catalyst preparation, resulting in higher BET surface areas; a spongy pore structure; more highly dispersed, pillared MnO(x) species; and higher density of acid sites distributed on catalysts surface, which all contributed to its superior performance for NH(3)-SCR. The activity for low-temperature NH(3)-SCR of manganese catalysts could be widely tailored by preparation methods.