Revealing active species of CePO_(4)catalyst for selective catalytic reduction of NO_(x)with NH_(3)

Revealing the active species of the catalyst is conducive to the design of more efficient catalyst.Herein,we tried to demonstrate the roles of amorphous and crystalline structures on CePO_(4)catalyst during selective catalytic reduction(SCR)of NO_(x)by NH_(3).Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO_(4).Both amorphous and crystalline CePO_(4)species on CePO-X samples can provide acid sites for NH_(3)adsorption,but the former can provide more acid sites.The superior redox property of surface amorphous CePO_(4)species contributes to its high NH_(3)-SCR activity at low temperature,but it also leads to the decrease of high temperature(>350℃)NH_(3)-SCR activity due to the oxidation of NH_(3).In contrast,crystalline CePO_(4)species shows high activity only at high temperature because of its poor redox property.Therefo re,it can be inferred that amo rphous and crystalline structures on CePO_(4)catalyst can be the efficient active species of NH_(3)-SCR at low and high temperature,respectively.