INFLUENCE OF SURFACE OXYGEN VACANCIES ON THE CATALYTIC ACTIVITY OF COPPER-OXIDE .1. OXIDATION OF CARBON-MONOXIDE

The reduction of copper oxide by carbon monoxide has been modelled by means of a cellular automaton, and the predictions of the model have been validated by experiments. In the model, carbon monoxide is adsorbed at an oxygen vacancy and subsequently reacts with a neighboring oxygen atom. Diffusion of oxygen proceeds in the bulk and on the surface of the copper oxide particle. In the case of a temperature-programmed reduction, the model predicts that all surface oxygen atoms are removed first, before the bulk oxygen starts to react. The model also predicts that during isothermal reduction the rate of reaction should increase with time. Both predicted phenomena were confirmed by experiments. The results of the reduction experiments were used to explain the catalytic activity of copper (oxide) for the catalytic oxidation of carbon monoxide in reducing and oxidizing atmospheres.