Active and Stable Supported MnO x -CeO x Mixed Oxide Catalysts for Low-Temperature NH 3 -SCR-DeNO x

High Resolution Image Download MS PowerPoint Slide The influence of the composition of MnO x -CeO x catalysts for low-temperature NH 3 -SCR-DeNO x supported on TiO 2 doped with different contents of SiO 2 on the conversion of NO x, the yield of N 2 O, and the stability in the presence of SO 2 and water were investigated. The dual redox cycle of MnO x and CeO x shifts the reduction temperature obtained by TPR-H 2 and the conversion of NO x during NH 3 -SCR-DeNO x to lower temperatures by roughly 25 K for MnO x -CeO x /TiO 2 -4SiO 2 with n Mn / n Ce = 4 compared to MnO x /TiO 2 -4SiO 2 . Above 473 K, the increased redox abilities cause an increased oxidation of NH 3 and formation of N 2 O. Doping the support with SiO 2 suppresses the oxidation of NH 3 to N 2 O above 573 K with no significant influence on the conversion of NO x in the absence of water. Water adsorption at 433 K reveals that the addition of 4.4 wt % SiO 2 reduces the water uptake by about 70% compared to the pure TiO 2 support, leading to improved resistance toward water poisoning during NH 3 -SCR-DeNO x . The protective effect of CeO x for MnO x in the presence of SO 2 results in a highly active and stable low-temperature NH 3 -SCR-DeNO x catalyst for exhaust gas treatment in stationary power plants.