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

The solvothermal synthesis of optimized micron-sized spherical Ce₁Mn₇O_x-350 yields remarkable results in ultra-low temperature NH₃-SCR of NO_x, with over 91 % NO_x conversion achieved between 59 and 255 ℃. Notably, under 5 vol% H₂O and 50 ppm SO₂, the Ce₁Mn₇O_x maintains NO_x conversion >99 % at 127 ℃ for extended periods, surpassing current ultra-low temperature deNO_x 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 deNO_x, 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 Ce₁Mn₇O_x facilitates rapid thermal dissipation and ammonium sulfite decomposition. This process is further augmented by the pores, which aid in the confinement of deNO_x reaction heat and facilitate the flushing of flowing flue gas, thereby impeding the formation of ammonium bisulfate.