非晶Ce-Ti氧化物用于NH_3选择性催化还原NO的原位红外研究

In situ IR studies of selective catalytic reduction of NO with NH_3 on Ce-Ti amorphous oxides

采用原位红外光谱研究了在具有短程有序Ce–O–Ti结构的非晶Ce-Ti氧化物上NH3选择性催化还原(SCR)NOx反应.在反应条件下,催化剂表面主要被NH3吸附物种覆盖,而检测不到NOx吸附物种.经测定,NO的反应级数为0.5–0.6,表明Langmuir-Hinshelwood机理和Eley-Rideal机理同时存在.可能的机理是NH3吸附物种和弱吸附的NOx反应,生成NHyNO3(y=0–4)活性中间物种,并通过GAUSSIAN计算和原位红外结果证实了它们的存在.Ce–O–Ti结构中Ce与Ti之间表现出原子尺度的相互作用,所以在SCR反应的活性温度窗口下,催化剂的氧化还原活性提高.

A series of in situ infrared（IR） studies of the selective catalytic reduction（SCR） of NOx with NH3 on the short‐range ordered structure Ce–O–Ti sites in amorphous Ce‐Ti mixed oxides were performed. Under the reaction conditions, the catalyst surface was mainly covered by NH3 ad‐species and no NOx ad‐species were detected. The reaction order of 0.5–0.6 with respect to NO confirmed a hybrid Langmuir‐Hinshelwood and Eley‐Rideal mechanism. A possible route may involve the reaction of NH3 ad‐species and weakly adsorbed NOx to form an active intermediate, NHyNO3（y = 0–4）; this was confirmed by GAUSSIAN calculations and the in situ IR results. The Ce–O–Ti structure, with Ce‐Ti interactions on the atomic scale, enhanced the redox properties in the active temperature window of the SCR reactions.