Preparation and behaviour of acetylene black press-electrodes as adsorbents and metal catalysts supports

Abstract

Acetylene black press-electrodes were prepared through stirring acetylene black in distilled water, mixing with a Teflon-emulsion and pressing the obtained compact mass on a nickel lattice. The above electrodes exhibit a large surface and show strong adsorptive properties, which were studied in the case of nitro compounds. The adsorptive properties of the acetylene black material become much more pronounced after its electrochemical pretreatment through application of alternated oxidative and reductive potentiostatic pulses. Through this procedure cation-exchangeable groups are created on the carbon surface, while simultaneously the effective area of the material becomes larger. Considerable amounts of nitro compounds can be attached to the electrooxidized material through a procedure of successive adsorption of the nitro compound and its electroreduction.Through ion-exchange of the electrooxidized material in aqueous solutions containing noble metal salts, followed by electrochemical reduction of the exchanged metal ions to the metallic state, catalytically active noble metal systems are obtained, Ag-modified electrodes were found to catalyze the electroreduction of aliphatic nitrocompounds, while Pd-modified electrodes showed catalytic activity in the electroreduction of nitrobenzene and the electrooxidation of formic acid. Moreover, Pd-modified systems proved to be very suitable for the catalysis of chemical reactions, eg, for the hydrogenation of benzoyl chloride and oleic acid.