Influence of tin doping on the activity and mechanism of CeO2catalyst for selective catalytic reduction of NOxwith NH3

Herein, the gelatin bio-template sol-gel self-combustion was confirmed to fabricate fluorite structured CeO2 catalyst with a high crystallinity, although the doping of Sn improved its NH3-SCR activity at medium-low temperatures due to the incorporating into the lattice of crystals. Furthermore, this doping restricted the growth of both SnO2 and CeO2 crystals in the mixed oxide catalyst and enlarged the BET surface area of CeO2 catalyst. Moreover, Ce4Sn2Oz presented the best catalytic performance mainly attributed to the largest low-temperature reactive oxygen species and weak acid sites. DFT calculations demonstrated that the doping of Sn induced new reactive sites formed on the CeO2 (111) surface and reduced the total energy barrier of NH3-SCR reaction. Furthermore, the doping of Sn changed the reaction path, and the decomposition process of NH4NO2 intermediate was the found as rate determining step for the NH3-SCR reaction over Sn-CeO2 (111), which was different from the activation of NH3 species on CeO2 (111).