Selective catalytic reduction of NO with NH3 over the Cu/SAPO-34 catalysts derived from different Cu precursors

Hydrothermal stability of the Cu(A, N, Cl or S)/SAPO-34 samples derived from different Cu precursors (A: Cu-acetate; N: Cu-nitrate; Cl: Cu-chloride; and S: Cu-sulfate) was investigated. The physical and chemical properties of the samples were investigated by various analytical techniques, and their catalytic activities for NO conversion and NH3 oxidation were evaluated. The results of NH3-SCR activity show that the Cu(A)/SAPO-34 sample was better than that of the Cu(N, Cl or S)/SAPO-34 sample, which was due to the existence of a less amount of CuO species and a more amount of the isolated Cu2+ species. Moreover, catalytic activities of all aged catalysts decreased in the whole temperature range, which was attributed to the drop in the amount of isolated Cu2+ species in the hydrothermally treated Cu/SAPO-34 samples. After hydrothermal aging treatment, part of the isolated Cu2+ was transformed to CuO, leading to structural instability and deactivation of the catalysts.