Deactivation by HCl of CeO 2 -MoO 3 /TiO 2 catalyst for selective catalytic reduction of NO with NH 3 .

The effect of HCl on a CeO 2 -MoO 3 /TiO 2 catalyst for the selective catalytic reduction of NO with NH 3 was investigated with BET, XRD, NH 3 -TPD, H 2 -TPR, XPS and catalytic activity measurements. The results showed that HCl had an inhibiting effect on the activity of the CeO 2 -MoO 3 /TiO 2 catalyst. The deactivation by HCl of the CeO 2 -MoO 3 /TiO 2 catalyst could be attributed to pore blockage, weakened interaction among ceria, molybdenum and titania, reduction in surface acidity and degradation of redox ability. The Ce 3+ /Ce 4+ redox cycle was damaged because unreactive Ce 3+ in the form of CeCl 3 lost the ability to be converted to active Ce 4+ in the SCR reaction. In addition, a decrease in the amount of chemisorbed oxygen and the concentrations of surface Ce and Mo was also responsible for the deactivation by HCl of the CeO 2 -MoO 3 /TiO 2 catalyst.