Solvent-free elaboration of Ni-doped MnOx catalysts with high performance for NH3-SCR in low and medium temperature zones

Abstract Cryptomelane-type Ni-doped MnOx catalysts (NMOs) prepared by solvent-free doping method showed very attractive performances in wide temperature zones and stability for selective catalytic reduction (SCR) at 100–300 ℃. The effect of Ni loading on NH3-SCR activity at medium temperature (200–300 ℃) was investigated. The NMOs-4 catalyst not only maintained excellent low temperature (100–200 ℃) NH3-SCR activity, the NO conversion was approached to 100 %, but also significantly improved the medium temperature activity while the NO conversion increased from 54.4% to 87.2% at 300 ℃ (T95 = 100–265 ℃) compared with undoped MOs catalyst (T95 = 100–225 ℃). Appropriate Ni loading could effectively tune the surface lattice oxygen activity and acidity of catalyst to ensure the NH3 activation ability at low temperature and inhibit the occurrence of NH3 direct oxidation at higher temperature. On other words, moderate NH3 activation capacity was the key to achieve a wide temperature region of MnOx-based catalysts.