Hydrodechiorination of 1,1,1-Trichioroethane over Silica-Supported Pd and Pt Catalysts Prepared by an Ion-Exchange Method

Silica-supported Pd and Pt catalysts were prepared by an ion-exchange method using ammoniacal solutions of [Pd(NH3)4]Cl2 and [Pt(NH3)4]Cl2. The catalyst precursors were calcined in air at prescribed temperature and reduced in a hydrogen stream at 450•Ž. The catalysts showed higher metal dispersion than those prepared by a conventional impregnation method. The Pt dispersion decreased with increasing the calcination temperature from 110 to 600•Ž, whereas the Pd dispersion did not change by the calcination at the temperatures lower than 450•Ž. Highly dispersed Pd and Pt catalysts exhibited higher selectivity to ethane in the hydrodechlorination of 1,1,1trichloroethane. Over Pd catalysts, hydrodechlorinative coupling reaction took place to form n-C4H10 at ca 10% selectivity. The turnover frequency of the hydrodechlorination did not depend on the metal dispersion.