A STUDY OF METALS SUPPORTED ON ACTIVE-CARBON WITH A TEMPERATURE-PROGRAMMED REDUCTION (TPR) TECHNIQUE

The influence of active carbon as support on the reducibility of supported metals (Ni, Cu, Cd, Zn) has been studied by means of a temperature programmed reduction (TPR) technique. The TPR profiles indicate that active carbon behaves as a dispersion agent and the supported metal is dispersed in a disordered phase rather than as a stoichiometric compound. The hydrogen consumed in the reduction indicates that the metal residues are present in monovalent and divalent forms. High-temperature reduction peaks were also observed and are explained on the basis of metal - surface interactions and the porosity of the active carbon. Nitrogen adsorption reveals that the active carbon porosity decreases due to progressive closure of the pores when metals are supported on the surface of active carbon.