The promotion effects of TiO 2 on the selective catalytic reduction of NO x with NH 3 over ceo 2 ‐WO 3 /ZrO 2 : The catalytic performance and reaction route

ZrO 2 ‐TiO 2 mixed oxides with different contents of TiO 2 were prepared by a co‐precipitation method, which were used as the carrier material of CeO 2 ‐WO 3 /ZrO 2 ‐TiO 2 catalysts. The influence of doping TiO 2 on NH 3 ‐SCR activity and reaction path of CeO 2 ‐WO 3 /ZrO 2 was systematically investigated by several techniques, including N 2 ‐physisorption, XRD, H 2 ‐TPR, XPS, NO x ‐TPD, NH 3 ‐TPD, and in situ DRIFTS. The activity result suggested that the CeO 2 ‐WO 3 /ZrO 2 ‐TiO 2 with 0.20 g/g TiO 2 exhibited the optimal NH 3 ‐SCR performance, its operational temperature window was broadened about 55 °C from 254–445 °C of CeO 2 ‐WO 3 /ZrO 2 to 221–467 °C of CeO 2 ‐WO 3 /ZrO 2 ‐TiO 2 . The characterization results indicated that the reducibility of CeO 2 ‐WO 3 /ZrO 2 was obviously improved by adding TiO 2 into ZrO 2 , which could improve the low‐temperature NH 3 ‐SCR activity. Besides, TiO 2 ‐doping enhanced the adsorption and activation of NH 3 , which played a positive role in NH 3 ‐SCR reaction. Finally, the results of in situ DRIFTS demonstrated that the NH 3 ‐SCR reaction route could be transferred from the Eley‐Rideal mechanism over CeO 2 ‐WO 3 /ZrO 2 to the Langmuir‐Hinshelwood mechanism over CeO 2 ‐WO 3 /ZrO 2 ‐TiO 2 at 250 °C.