Structure, Reducibility and Catalytic Activity of Nickel-ruthenium Composite Oxide Catalysts

Abstract

The reduction characteristics of alumina supported nickel-ruthenium composite oxide catalysts were investigated by a thermal analysis method. The reduction peak of ruthenium oxide was found at 150°C. A nickel-ruthenium composite oxide, low in the ruthenium content, showed a single reduction peak at a temperature lower than that of nickel oxide. The catalytic activity was tested with hydrogenation of acetone. As a general tendency, the catalytic activity increased with the reduction temperature below 400°C, irrespective of the amount of nickel loaded on the catalyst carrier and the amount of ruthenium addition. However, the catalyst, reduced above 400°C, showed a remarkable decrease in the activity.H₂ chemisorption behavior indicated a characteristic tendency, corresponding to the catalytic activity. From consideration of both the amount of H₂ chemisorbed on the catalyst and the current distribution in depth from the catalyst surface, it is concluded that the surface area of exposed metal on the catalyst is decreased by the catalyst diffusion into the carrier as well as sintering of the catalytic metal.