Hydrogen-Water Deuterium Exchange Reaction Over Mixed Oxide Supported Nickel Catalysts

Three series of catalysts, Ni/Al₂O₃-SiO₂, Ni/Al₂O₃-Cr₂O₃ and Ni/SiO₂-Cr₂O₃, were prepared by co-precipitation. In all samples the nickel content was kept constant at 70 at.% Ni, while the support composition was varied. The nickel surface areas, which are required to measure the specific catalytic activities, were determined by hydrogen chemisorption. In the case of the single oxide supported nickel catalysts, the order of the specific catalytic activity values was: Ni/Cr₂O₃<Ni/Al₂O₃<Ni/SiO₂. The specific catalytic activity of the Ni/Al₂O₃-SiO₂ samples, as a function of the support composition, follows approximately the weighted sum of the specific activities of the single oxide supported nickel catalysts. The specific catalytic activity value of the Ni/Al₂O₃-Cr₂O₃ and Ni/SiO₂-Cr₂O₃ samples more closely resembled that of Ni/Cr₂O₃ catalyst. The presence on chromia surface of the chromic anhydride and its tendency to spread onto are supposed to be the cause of this behaviour. Due to their enhanced activity, the Ni/Al₂O₃-Cr₂O₃ catalysts can be used for the production and detritiation of heavy water.