Ultradispersed diamond as a new carbon support for hydrodechlorination catalysts

The properties of palladium and nickel catalysts supported on ultradispersed diamond (UDD) were studied in the vapor-phase hydrodechlorination (HDC) reaction of chlorobenzene and the multiphase HDC of polychlorobenzenes. The catalysts on UDD exhibited a number of advantages: the vapor-phase HDC of chlorobenzene on Ni/UDD occurred at lower temperatures, and the multiphase HDC of chlorobenzene, 1,3,5-trichlorobenzene, and 2,4,8-trichlorodibenzofuran on Pd/UDD occurred more rapidly than that on catalysts supported on activated carbon. The structure of the catalysts and the electronic states of the active components were studied using IR spectroscopy, temperature-programmed reduction, and adsorption techniques. It was found that the properties of the catalysts depend on the electronic state of palladium, which depends on its concentration in the sample; the structural properties, which are responsible for the accessibility of the active surface to adsorption; and the presence of other metal impurities.