Studies On Water-phase Hydrodechlorination Of Chlorinated Organic Compounds Over Cobalt-based Catalysts

Chlorinated organic compounds (COCs) are major pollutants in waste water, which bring harm to the environment and turn to be a threat human body. Among the available various detoxification techniques, catalytic hydrodechlorination (HDC), which is gradually taken into account in recent years, is an feasible one that can be employed to eliminate chlorinated organic pollutants under mild conditions.In this dissertation, taking Pd/Co catalytic system as the case research object, a series of catalysts were prepared with different methods, also characterized and tested by means of BET, XRD, TEM, SAED, ESR, EDS, ICP-AES and water-phase hydrodechlorination performance of monochlorobenzene, dichlorobenzene and trichlorobenzene at ambient temperature and pressure conditions.The surface area of amorphous CoPdB-1 catalyst with precipitation-reduction preparation method was the largest than other methods. Because the Pd species were highly dispersed on the cobalt whose valence was+1, this may lead to the strong interaction between Pd and Co species which was beneficial to the hydrogen and C-Cl bond dissociative chemisorption on the electron-deficient centers. The dechlorination efficiency of amorphous catalysts was much higher than that of crystalline samples due to the structural and electronic effect. Moreover, the amorphous CoPdB-1 catalyst can be used at least three times without loss of its high catalytic activities, even after running five times cycles, the conversion of MCB was still up to 80%. Additionally, the CoPdB-1 catalyst with strong magnetism can be easily recovered by using an external permanent magnet, which will greatly promote their industrial application to eliminate the chlorobenzene from wastewater.Doping with Ni, the Pd active species on the surface of amorphous CoPdNiB-1 catalyst with precipitation-reduction preparation method were further highly dispersed on the cobalt and less likely to agglomerate. With the optimal weight ratio of Pd:Ni:Co which was 5:10:100, the dechlorination efficiency of CoPdNiB-1 was almost equal to CoPdB-1.