In situ IR studies of selective catalytic reduction of NO with NH3 on Ce-Ti amorphous oxides

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.

Graphical AbstractThe selective catalytic reduction of NOx with NH3 on a short-range ordered Ce–O–Ti structure was confirmed to involve the reaction of NH3 ad-species, and weakly adsorbed NOx to form an intermediate, NHyNO3 (y = 0–4).Figure optionsDownload as PowerPoint slide