Ultra-low temperature selective catalytic reduction of NOx into N2 by micron spherical CeMnOx in high-humidity atmospheres containing SO2

The solvothermal synthesis of optimized micron-sized spherical Ce1Mn7Ox-350 yields remarkable results in ultra-low temperature NH3-SCR of NOx, with over 91 % NOx conversion achieved between 59 and 255 ℃. Notably, under 5 vol% H2O and 50 ppm SO2, the Ce1Mn7Ox maintains NOx conversion >99 % at 127 ℃ for extended periods, surpassing current ultra-low temperature deNOx standards. This superior performance is attributed to the material's unique characteristics: the regular and porous surface morphology enhances exposure to active sites, particularly Mn3O4(112) facets crucial for ultra-low temperature deNOx, while the rough and loose surface and high Mn2O3(222) exposure mitigate water vapor and SO2 poisoning. Furthermore, the thermal storage effect of the Mn2O3/Mn3O4 system within Ce1Mn7Ox facilitates rapid thermal dissipation and ammonium sulfite decomposition. This process is further augmented by the pores, which aid in the confinement of deNOx reaction heat and facilitate the flushing of flowing flue gas, thereby impeding the formation of ammonium bisulfate. © 2024 Elsevier B.V.