Modification of the Catalytic Behavior of Cobalt by the Addition of Copper

Abstract

The interaction of ethylene and ethylene/hydrogen mixtures with cobalt and copper-doped cobalt has been studied using a combination of flow reactor and transmission electron microscopy techniques. From the analysis of both gas product distribution and the amount of solid carbon formed, it was possible to follow changes in the fraction of cobalt atoms present in the surface of the bimetallic catalyst as a function of time, temperature, and gas composition. The results of this investigation highlight the manner by which the incorporation of copper can enhance the catalytic activity of cobalt particles toward the formation of filamentous carbon. In addition, it has been demonstrated that the composition of the reactant gas plays an important role in determining the performance of the catalyst. In some cases the presence of hydrogen in the reactant is essential in order to induce catalytic activity and extend the life of the bimetallic particles to higher operating temperatures. The inclusion of copper modifies the morphology of the cobalt particles to such an extent that both the structural conformation and degree of crystallinity of the deposited carbon created from the decomposition of ethylene is completely different to that when unadulterated cobalt is reacted under the same conditions.more » 73 refs., 9 figs., 3 tabs.« less