Selective oxidation of propene using an electrochemical membrane reactor with CeO2-based solid electrolyte

The partial oxidation of propene to acrylaldehyde on an inert gold electrode has been studied at 350 to 450 degrees C over an electrochemical membrane reactor using (CeO2)(0.8)(SmO1.5)(0.2) as a solid electrolyte. This material has a high ionic conductivity at low temperatures. On applying a direct current to the reaction cell, acrylaldehyde was formed at the gold anode, and the formation rate of acrylaldehyde increased linearly with increasing current density. The addition of oxygen to the propene-mixed gas at the anode space did not affect the acrylaldehyde production. Hence, it is likely that partial oxidation of propene was carried out by the oxygen species produced electrochemically through the electrolyte, and appearing at the gold-electrolyte gas-phase triple-phase boundary. From the dependence of the acrlylaldehyde selectivity on the amount and the type of dopants, it was found that the complete oxidation of propene with lattice oxygen from the rare-earth-doped CeO2 surface was significant, and that the reactivity of lattice oxygen in CeO2 with hydrocarbons decreased with increasing ionic conduction of the oxide.