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. (C) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.