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/TiO2 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 NH3-SCR reaction over Ce/TiO2 catalyst takes place though two pathways: the L-H mechanisms (<200 degrees C) and the E-R mechanism (>200 degrees C). For CeiTiO(2)-Ca, the NH3-SCR reaction over ins mainly controlled by L-H mechanism. The deactivation of CeiTiO(2)-Ca lies in the following two aspects: (1) the inhibited NH3 adsorption and NO oxidation (<200 degrees C); (2) the greatly suppressed NH3 adsorption and activation (>200 degrees C). (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.