Effect of second metals and Cu content on catalyst performance of Ni-Cu/SiO2 in the hydrodechlorination of 1,1,2-trichloroethane into vinyl chloride monomer

The hydrodechlorination of 1,1,2-trichloroethane (TCEA), which is one of the chlorinated organic wastes produced in the ethylene dichloride process, to vinyl chloride monomer (VCM) was carried out over Ni-Cu/SiO(2) catalysts. The effects of added metals from IB group and the Cu content on the performance of the bimetallic catalysts were systematically investigated. Of the screened bimetallic catalysts tested, Ni-Cu/SiO(2) catalysts efficiently converted TCEA into VCM in 95% or higher selectivity. Cu in Ni-Cu/SiO(2) reduced the metal particle size and weakened the adsorption strength of Ni, and led to low conversion of TCEA and a high VCM selectivity. A series of CO-IR and extended X-ray absorption fine structure (EXAFS) measurements revealed that added Cu had no effect on the electronic structure of Ni and that Cu altered the geometric nature of Ni-Cu/SiO(2) catalyst. HCl converted metallic Ni to NiCl(2) and Cu to CuCl to modify the crystal structure. Cu played a role in the cooperation with Ni in the hydrodechlorination of TCEA, serving as other than an inert spacer. (C) 2001 Elsevier Science B.V. All rights reserved.