Trapping of radiolytic hydrogen by amorphous cobalt oxysulfide

Hydrogen production from the radiolysis of liquid and gaseous hydrocarbons was studied in the presence of several transition metal sulfides. Cobalt oxysulfide obtained by aqueous precipitation was the most efficient admixture to decrease radiolytic production of hydrogen by pure hydrocarbons or mixtures of saturated and unsaturated hydrocarbons. Cobalt oxysulfide was characterized by XRD, scanning and transmission microscopy, and IR spectroscopy. It seems to be amorphous compound with the impurities of lamellar Co(OH)2 phase. The organic phases were analysed before and after irradiation by γ-rays or protons in order to elucidate the origin of the effect. It has been shown that the solid does not change the composition neither the amount of the organic radiolysis products, neither in liquid nor in gas phase experiments. Therefore the presence of solid does not influence any radiolysis processes in the organics. Amorphous cobalt oxysulfide acts essentially as a trap of hydrogen, being able to absorb considerable amounts of H2 (up to 0.5 mol H2/at. Co). The study of the solid-gas interaction showed that slow reaction of cobalt oxysulfide with hydrogen occurs at ambient conditions independently of the irradiation of the system.