Effect of Hydrothermal Treatment and Chemical Deactivation on the Activity of Cu-SSZ-13 in NH3-SCR
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The effect of hydrothermal treatment and chemical deactivation on the Ammonia Selective Catalytic Reduction (NH3-SCR) with Cu-SSZ-13 zeolite as the catalyst has been studied. The Cu-SSZ-13 samples were first hydrothermally treated at 730 ℃ for 13h and then subsequently individually impregnated via Wet Impregnation method with the chosen chemical species, with either Ca, P, Pt or Zn. The samples were characterized with XRD, IR, UV-Vis and/or N2 physisorption methods and catalytic tests were performed under the Standard SCR reaction conditions within a temperature range of 150-450 ℃. Hydrothermal treatment caused considerable catalyst deactivation due to clustering of the catalytically active Cu2+ ion to inactive Cu oxides. Impregnation with Pt caused formation of Pt0 on the hydrothermally treated Cu-SSZ-13 catalyst which resulted in severe loss in the reaction selectivity. P-impregnation caused complete deactivation of the Cu-SSZ-13 up to reaction temperature of 350 ℃ due to unidentified P-species. Ca and Zn impregnations resulted in less severe catalyst deactivation than the P and Pt impregnations. For Ca, presence of Ca2+ was observed but the deactivating species was not definitely identified while for the Zn-impregnation catalyst deactivation was caused by the formed ZnO.