Relationship between structure and performance of a novel highly dispersed MnOx on Co-Al layered double oxide for low temperature NH3-SCR

A series of novel highly dispersed MnOx on Co-Al layered double oxide catalysts were fabricated for the low temperature NH3-SCR reaction. The Mn(0.25)/LDO exhibited outstanding catalytic performance with a unique multi-layered structure, which could achieve approximately 100% conversion of NOx in the range of 150-300 degrees C with a GHSV of 40,000 h(-1), as well as excellent H2O or SO2 tolerance and thermal stability. Various characterized techniques were applied to investigate the structural-activity relationship in the SCR reaction. The relative results indicated that the manganese addition could increase the quantity of Mn4+, surface adsorbed oxygen species, reducibility and ammonia adsorption capacity. Meanwhile, this strong interaction between Co-Al LDO and highly dispersed manganese species could significantly increase the positive charge density around Mn cations (Lewis acid sites) based on DFT calculated and in situ DRIFTS. Furthermore, it is proved that the NH3-SCR reaction over Mn(x)/LDO mainly follow E-R reaction pathway.