Studies in catalytic combustion.—part II. The union of carbon monoxide and oxygen in contact with nickel, copper and their oxides

After investigating the action of gold in causing the union of carbon monoxide and oxygen at temperatures between 275° and 325° C., as already described in Part I of this series,* we turned our attention to nickel, copper and their oxides, as examples of surfaces which certainly are not chemically indifferent to the reacting gases. For, as is well known, freshly reduced nickel forms a carbonyl with carbon monoxide at quite moderate temperatures (30° to 80° C.), and copper (as we have found) is by no means indifferent to the gas at somewhat higher temperatures. Again, whilst copper very readily combines with oxygen at moderate temperatures, nickel is more resistent to oxidation, but, like iron, will burn if sufficiently heated in oxygen. Nickel, therefore, has a greater affinity for carbon monoxide, but a less affinity for oxygen, than has copper ; also, their oxides are all readily reducible by carbon monoxide at moderate temperatures. Altogether, the properties of these two metals and their oxides are such as would seem to be highly conducive to “catalytic” activity towards mixtures of carbon monoxide and oxygen, if, in any circumstances, such activity is essentially chemical. Hence our choice of them for a detailed experimental study, the results of which are summarized in this paper. The apparatus and experimental method employed were in all essential respects the same as those already detailed in Part I hereof, namely, the “circulation method” as introduced by Bone and Wheeler, with the inclusion of a suitable arrangement for continuously removing the reaction product (CO 2 ) from the system by means of a solution of purified barium hydroxide. Also, the plan of recording the experiments in their chronological sequence will again be adopted, using the same symbols as before.