The poisoning effect of PbO and PbCl2 on CeO2-TiO2 catalyst for selective catalytic reduction of NO with NH3.

The poisoning effect of PbO and PbCl 2 on CeO 2 -TiO 2 catalyst for selective catalytic reduction of NO with NH 3 was investigated and compared. Both Pb species could deactivate the CeO 2 -TiO 2 catalyst and PbO had a stronger poisoning effect than PbCl 2 . From the characterization results of BET, XRD, XPS, NH 3 -TPD and H 2 -TPR, it was concluded that the more serious deactivation by PbO could be ascribed to smaller BET surface area, fewer surface Ce 3+ and chemisorbed oxygen, stronger interaction between PbO and CeO 2 -TiO 2 catalyst, lower redox properties and surface acidity. The in situ DRIFT study results revealed that the NH 3 -SCR reaction over CeO 2 -TiO 2 catalyst was governed by both E-R and L-H mechanisms, which wasn’t changed over the Pb-poisoned samples. The greater loss of Brønsted acid sites attributed to fewer surface Ce 3+ and more serious inhibition of NO oxidation to NO 2 due to fewer surface chemisorbed oxygen were two key factors responsible for more serious deactivation by PbO. Furthermore, the presence of Pb species inhibited the NH 3 adsorption on the Lewis acid sites, aggravating the deactivation of CeO 2 -TiO 2 catalyst. [ABSTRACT FROM AUTHOR]