Effects of copper precursors on catalytic performance of Cu/SSZ-13 catalyst for NH3 selective catalytic reduction of NO

Abstract:

Cu/SSZ-13 catalysts with the nearly same content of copper species were prepared by ion exchange technology with copper acetate, copper chloride, copper nitrate and copper sulfate as precursors, respectively. The effects of copper source on NH₃ selective catalytic reduction (NH₃-SCR) were probed detailedly. The physicochemical properties of the catalysts were investigated by XRD, ICP, N₂ absorption-desorption, SEM, H₂-TPR, XPS and NH₃-TPD. The results of activity test display that the performance of Cu/SSZ-13 zeolite for ammonia selective catalytic reduction at low temperature is significantly different. The light off temperature T50 (the temperature when conversion efficiency ≥ 50 %) follows the order of Cu (copper acetate) / SSZ-13 < Cu (copper chloride) / SSZ-13 < Cu (copper sulfate) / SSZ-13 < Cu (copper nitrate) / SSZ-13. The characterization results manifest that the distribution and quantity of copper species and the acidity of zeolite catalysts are affected by copper source. The Cu/SSZ-13 catalyst prepared with copper acetate as precursor possesses the largest number of isolated Cu^₂₊ and strong L acid sites, which are conducive to the low-temperature NH₃-SCR reaction.