Selectivity and stoichiometry of copper oxide in propylene oxidation

The oxidation of propylene to acrolein on the surface of a cuprous oxide crystal was studied. Simultaneous in situ measurements were carried out of the catalytic activity, the electrical conductance, and the optical properties of the catalyst. The results indicate that the most active solid phase for acrolein formation is stoichiometric or copper-rich cuprous oxide. Oxygen-rich cuprous oxide and cupric oxide, on the other hand, favor complete oxidation of propylene to carbon dioxide and water. A mechanism is postulated that is based on a solid-state model with surface state energy levels.