Catalytic decomposition of nitrogen oxide over Cu/HZSM-5 catalysts prepared by different methods

Cu/HZSM-5 catalysts were prepared by different methods of ion exchange, solid-state dispersion and solid-state microwave irradiation. The obtained Cu/HZSM-5 catalysts were characterized by means of BET, XRD and XPS. Experimental results exhibited that the location of Cu species was strongly dependent on the preparation method. Cu species on the external surface of the zeolite prepared by solid-state microwave irradiation and solid-state dispersion are more than ion exchange. And the crystalline diffraction peaks of CuO species can be found in the samples prepared by solid-state dispersion. In addition, the catalytic performance of the catalyst for NO catalytic decomposition was investigated. Compared with the other two methods, the catalysts prepared by solide-state microwave irradiation showed higher catalytic activity and stability for NO catalytic decomposition. Under anaerobic conditions, the NO conversion was up to 89.2% and could remain at 70%, after 25h. Under the condition of excess oxygen, the deactivation rate of the catalyst was lower than that of the catalysts prepared by ion exchange. Corresponding with the characterization results, we can draw a conclusion that the Cu species, which exist as ion exchange state on the external surface of zeolite, are helpful to the decomposition of NO reaction and its catalytic stability is better.