Liquid-phase hydrodechlorination of CCl4 in a medium of acetal and diethyl carbonate

Abstract

During the liquid-phase hydrodechlorination (HDC) Of CCl4 over supported Pd or Pt catalysts in the presence of C2H5OH and molecular oxygen, the selective catalytic synthesis of CHCl3 as well as the conversion of C2H5OH to diethyl carbonate (DEC) and 1,1-diethoxyethane (DEE) was observed. The protic solvent, C2H5OH, could easily donate proton that reacts with the adsorbed chlorine on the catalyst surface to form HCl. This facile removal of chlorine from the catalyst surface could be the main reason for the enhancement of the catalytic stability and conversion of C2H5OH. The rate of DEC formation was accelerated with the increase in the partial pressure of molecular oxygen, and the selectivity to DEE was enhanced by the increased surface acidity of catalysts. Compared to the reactions of the hydrodechlorination of CCl4 without C2H5OH, the conversion of CCl4 and the selectivity to CHCl3 was greatly enhanced in the presence of C2H5OH. (C) 2003 Elsevier B.V. All rights reserved