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

Abstract

The poisoning effect of PbO and PbCl2 on CeO2-TiO2 catalyst for selective catalytic reduction of NO with NH3 was investigated and compared. Both Pb species could deactivate the CeO2-TiO2 catalyst and PbO had a stronger poisoning effect than PbCl2. From the characterization results of BET, XRD, XPS, NH3-TPD and H2-TPR, it was concluded that the more serious deactivation by PbO could be ascribed to smaller BET surface area, fewer surface Ce3+ and chemisorbed oxygen, stronger interaction between PbO and CeO2-TiO2 catalyst, lower redox properties and surface acidity. The in situ DRIFT study results revealed that the NH3-SCR reaction over CeO2-TiO2 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 Ce3+ and more serious inhibition of NO oxidation to NO2 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 NH3 adsorption on the Lewis acid sites, aggravating the deactivation of CeO2-TiO2 catalyst.