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 CePO₄ catalyst during selective catalytic reduction (SCR) of NO_x by NH₃. Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO₄. Both amorphous and crystalline CePO₄ species on CePO-X samples can provide acid sites for NH₃ adsorption, but the former can provide more acid sites. The superior redox property of surface amorphous CePO₄ species contributes to its high NH₃-SCR activity at low temperature, but it also leads to the decrease of high temperature (>350 °C) NH₃-SCR activity due to the oxidation of NH₃. In contrast, crystalline CePO₄ species shows high activity only at high temperature because of its poor redox property. Therefore, it can be inferred that amorphous and crystalline structures on CePO₄ catalyst can be the efficient active species of NH₃-SCR at low and high temperature, respectively.

揭示催化剂的活性物种有利于设计更高效的催化剂。在此，我们试图证明在NH _{3对 NO x}进行选择性催化还原 (SCR) 过程中，无定形和晶体结构对 CePO ₄催化剂的作用。较高的煅烧温度促进了CePO ₄表面上非晶结构向晶体结构的转变。CePO- X样品上的无定形和结晶CePO ₄物质都可以为NH ₃吸附提供酸性位点，但前者可以提供更多的酸性位点。表面无定形 CePO ₄物种优异的氧化还原性能有助于其高 NH ₃-SCR 活性在低温下，但也导致高温（>350 ℃）NH ₃ -SCR 活性因NH ₃的氧化而降低。相反，结晶CePO ₄物质由于其较差的氧化还原性能而仅在高温下显示出高活性。因此，可以推断CePO _{4催化剂上的无定形和晶体结构可以分别是NH 3} -SCR在低温和高温下的有效活性物种。