Palladium Catalysts on Carbon Supports. 1. General Features of Adsorption of H2PdCl4 on Carbon Supports
Russian Chemical Bulletin
, E-ISSN: 1573-9171
||Chloride Palladium Adsorption Site Carbon support Palladium catalyst
Institute of Catalysis, Siberian Branch, Academy of Sciences of the USSR
Impregnation of a carbon support (CS) with a solution of H2PdCI 4 with subsequent reduction is the traditional method of preparation of Pd/C catalysts. The nature of the CS has a significant effect on the properties of the catalysts obtained [I]. This is due to the differences in the type of distribution of the active component with respect to the support
grain and the effect of the pore structure of the CS on the dispersion of the catalysts obtained [2, 3], considering the support an inert substrate. It is also possible that the character of the reaction of the surface of the CS with Pd(ll) compounds in the stage of impregnation of the support with the H2PdCI 4 solution also affects the formation of active
sites. It was noted in [i, 4-6] that H2PdCI 4 is adsorbed on active carbon in significant quantities. It was hypothesized in [5, 6] that metal particles are formed. The effect of the degree of oxidation of the surface of the CS on the dispersio n of the applied metallic phase was demonstrated in . However, the nature of the reaction of H2PdCI 4 with
the surface of the CS has not been examined in detail. The features of adsorption of H2PdCI ~ on different CS were investigated in the present study.
1. The reaction of H2PdCl4 with carbon supports results in the formation of chloride complexes of Pd(II) with adsorption sites located on the unoxidized sections of the surface.
2. At least three types of H2PdCl4 adsorption sites which differ in the strength of the complexes with Pd(II) formed and the reactivity to the effect of oxidants were found. It was hypothesized that the elements of the π system of the carbon support are the adsorption sites of Pd(II).