Catalytic activity of Cu-SSZ-13 prepared with different methods for NH3-SCR reaction

A series of Cu-SSZ-13 catalysts with the same Cu loading were prepared by different methods of incipient wetness impregnation [Cu-SSZ-13(IWI)], ion exchange[Cu-SSZ-13(IE)] and hydro-thermal synthesis [Cu-SSZ-13(HTS)]. Their activity for selective catalytic reduction of nitrogen oxides(NO) with NH3 was determined. The results show that the Cu-SSZ-13(HTS) catalyst exhibits a better ammonia selective catalytic reduction(NH3-SCR)activity compared with the other two catalysts, over which more than 90% NO conversion is obtained at 215-600℃under the space velocity of 180,000 h. The characterization results reveal that the Cu-SSZ-13(HTS) catalyst possesses more amount of stable Cuin the six-membered ring and high ability for NH3 and NO adsorption, leading to its high NH3-SCR activity, although this catalyst has low surface area. On the other hand, the activity of Cu-SSZ-13(IE) catalyst is almost the same as that of Cu-SSZ-13(IWI) catalyst at the temperature lower than 400 ℃, but the activity of the former is much higher than that of the latter at > 400 ℃ due to the high activity of Cu-SSZ-13(IWI) catalyst for NH3 oxidation.