The effect of Ce–Zr on NH 3 -SCR activity over MnO x (0.6)/Ce 0.5 Zr 0.5 O 2 at low temperature

A series of Mn/Ce–Zr-based catalysts with various Ce/Zr ratios and Mn loadings were employed to investigate the selective catalytic reduction (SCR) of NO at low temperatures. The physicochemical properties of these catalysts were investigated by a variety of characterization methods. The experimental and kinetic model results showed that the MnOx(0.6)/Ce0.5Zr0.5O2 catalyst exhibited high NO conversion (nearly 100%) at low temperature, good resistance to H2O and SO2 and high N2 selectivity. The apparent activation energy of the MnOx(0.6)/Ce0.5Zr0.5O2 catalyst was 18.08 kJ mol−1, which is much lower than that of MnOx/TiO2 (38 kJ mol−1). The presence of ZrO2 in the catalyst introduced high total H2 consumption, surface acidity and Brunauer–Emmett–Teller (BET) specific surface area, and the introduction of CeO2 to the catalyst lowered the H2 reduction temperature and enhanced the Mn4+/Mn3+ ratio and adsorbed oxygen species on the surface. The combination of the advantages of the ZrO2 and CeO2 supports contributed to the highest NO conversions for MnOx(0.6)/Ce0.5Zr0.5O2 catalyst.