Study of Sandwich Type Raney Nickel Catalyst by Electron Microprobe X-Ray Analyzer

Abstract

The thickness of layer of sandwich type Raney nickel alloy was measured, and the distribution of sulfur bound to the catalyst surface was observed by means of an electron microprobe X-ray analyzer.The alloy layer, heated at 650°C under a nitrogen atmosphere and then pressed by a dental roller, was about 20 μ thick. The Raney nickel catalyst prepared from this alloy was active in hydrogenation of acetone. When the catalyst was immersed for 15 sec. in a saturated aqueous solution of H2S at 20°C, a large amount of sulfur was found distributed uniformly on its surface (Fig.3(c)). The catalyst thus treated lost its activity. The amount of surface sulfur detected after immersing an ordinary nickel plate, which was inactive for the hydrogenation of acetone, in a H2S solution was very small.When the catalyst was annealed at various temperatures up to 800°C in a hydrogen stream, the catalytic activity decreased abruptly at 400°C. The more the decrease in activity by the annealing, the less the amount of sulfur found on the surface after immersion in a H2S solution.These observations may lead to a conclusion that, as sulfur poisons active centers on the catalyst surface, the relation between the catalytic activity and the amount of sulfur is qualitatively parallel.