Catalytic Transfer Hydrodechlorination of Plastic Pyrolysis Oil on Supported Transition-Metal Catalysts Using Isopropanol as a Hydrogen Donor

Catalytic transfer hydrodechlorination of plastic pyrolysis oil on supported transition-metal catalysts using isopropanol as a hydrogen donor was investigated in this work. The catalysts were characterized by N2 adsorption, X-ray diffraction, hydrogen temperature-programmed desorption, and X-ray photoelectron spectroscopy, and the reaction products were identified by GC-MS. Among various Al2O3-supported transition-metal (Cu, Co, Ni) catalysts, Cu/Al2O3 exhibited the best catalytic transfer hydrodechlorination performance due to the superior activation ability of Cu/Al2O3 for isopropanol. The doping of Ni in Cu/Al2O3 significantly enhanced its catalytic activity due to the inherent excellent hydrogenation activity of Ni, good metal dispersion, and strong Ni–Cu interaction in Ni–Cu/Al2O3. GC-MS results revealed that chlorobenzene was hydrogenated to benzene and HCl, and isopropanol was dehydrogenated to form acetone, which was subsequently transformed to methyl isobutyl ketone. The reactivities of three representative organochlorine compounds followed the order of chlorobenzene > tetrachloroethane > tetrachloroethylene. Ultradeep dechlorination of real plastic pyrolysis oil was achieved by catalytic transfer hydrodechlorination over the optimal 15Ni-10Cu/Al2O3 catalyst. The chlorine content of real plastic pyrolysis oil was reduced from 61.7 to 0.5 mg/L with a chlorine removal of 99.2% after reaction for 3 h at the reaction temperature of 210 °C.