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.