Preparation and Characterization of Mesoporous CuO/ZSM-5 Catalysts for Automotive Exhaust Purification

Mesoporous zeolite ZSM-5 was prepared from microporous zeolite ZSM-5 treated with alkaline solution. Then CuO/ZSM-5 catalysts were successfully fabricated by an equal volume impregnation method. The texture structure, crystal phase, and acidity were characterized by N-2 physisorption-desorption, X-ray diffraction (XRD), F- scanning electron micrographs (SEM), and NH3-TPD techniques. The results showed that the mesoporous surface area and pore volume of ZSM-5 treated with alkali increased significantly from 77 m( )(2)g(-1) and 0.086 cm(3) g(-1) to 192 m(2) g(-1) and 0.326 cm(3) g(-1), respectively. The mesoporous surface area and mesoporous pore volume of ZSM-5 loaded with CuO decreased slightly. XRD patterns showed that the crystallinity of the zeolite decreased gradually with the increase of alkali concentration. The XRD patterns of the CuO/ZSM-5 samples indicated high CuO dispersion in the zeolites treated by alkali. All zeolites have the MFI framework topology. The catalytic activity of CuO/ZSM-5 series for simulating automobile exhaust shows that the optimum catalyst is CuO/ZSM-5(0.5). To purify auto-exhaust, the CuO/ZSM-5 exhibited improved catalytic activities than that of ZSM-5 and the conversion rate of NO, CO, and C3H6 was 100%, 85.87%, and 100%, respectively.