Deactivation mechanism of Ca on Ce/TiO2 catalyst for selective catalytic reduction of NOx with NH3

Ca salts in fly ash have a deactivation effect on SCR catalyst. In this study, the deactivation mechanism of Ca on Ce/TiO 2 catalyst was investigated in term of the in situ DRIFT study. The experimental results indicate that the poisoning effect increases with reaction temperature. From the results of in situ DRIFT study, it may be concluded that the NH 3 -SCR reaction over Ce/TiO 2 catalyst takes place though two pathways: the L -H mechanisms (<200 °C) and the E-R mechanism (>200 °C). For Ce/TiO 2 -Ca, the NH 3 -SCR reaction over it is mainly controlled by L -H mechanism. The deactivation of Ce/TiO 2 -Ca lies in the following two aspects: (1) the inhibited NH 3 adsorption and NO oxidation (<200 °C); (2) the greatly suppressed NH 3 adsorption and activation (>200 °C).