Studies of the nickel-catalyzed hydrogenation of graphite

Abstract

Controlled atmosphere electron microscopy has been used to study the effects of small nickel particles on the hydrogenation of single crystal graphite. These particles propagated channels in the graphite basal plane, the majority of these channels being parallel to the 〈112̄0〉 directions. Increase in channel propagation rate occurred with increase in temperature, but at temperatures above 1075 K nickel particle disappearance was frequent, believed to be due to diffusion of metal into the graphite structure. At higher temperatures graphite platelets were formed from immobile nickel particles. Quantitative analysis also revealed that the rate of carbon gasification was proportional to the external surface areas of individual particles and not to the leading catalyst/graphite interfacial area. All these effects and possible reaction mechanisms are discussed.