Catalytic dechlorination of polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins with supported noble metal catalysts

Abstract

Catalytic dechlorination of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins (PCDDs) was carried out in a solution of NaOH in 2-propanol with supported noble metal catalysts under mild conditions. In the presence of Pd/C or RhIC, dechlorination of PCBs (KC-400) efficiently occurred at temperatures below 82°C to give biphenyl as a main chlorine-free product. PCDDs such as 2, 7-dichlrodibenzo-p-dioxin (2, 7-DCDD) and 1, 2, 6, 7-tetrachlorodibenzo-p-dioxin (1, 2, 6, 7-TCDD) were converted to dibenzo-p-dioxin with Pd/C at 30°C. It was proposed that the dechlorination reaction includes hydrogen transfer from 2-propanol to organic chlorides.