Hydrodechlorination Of Chlorinated Aromatics Over Nickel Based Catalysts

The disposal of chlorinated organic wastes is a serious environmental problem. The catalytic hydrodechlorination (HDC) is receiving more and more attention because it is simple, effective and safe.Liquid phase hydrodechlorination of chlorobenzene was studied over Ni/active carbon (Ni/AC). The complete hydrodechlorination of chlorobenzene was realized at 333-343 K on Ni/AC under hydrogen atmosphere of 1.0 MPa in the presence of alkaline hydroxide. Aryl halides, three chlorotoluenes (o-, m-, and p-), three chloroanilines, three chlorobenzotrifluorides, three dichlorobenzenes and two trichloro- benzenes (1, 2, 3- and 1, 2, 4-) were also completely hydrodechlorinated (Conversion ~100%) under the similar conditions.The activity of Ni was greatly affected by support, diameter and distribution of Ni particles and preparation methods. The addition of Ag enhances the catalytic performance of nickel supported on activated carbon. The steric effect of chlorobenzene derivatives gave a large influence on the product distribution.Transformer oil containing PCBs was directly treated by nanometric sodium hydride (nano-NaH) and transition metal catalysts. High destruction and removal efficiency (99.9%) can be attained under mild conditions.