Contribution to the study of isotopic exchange of oxygen between nickel oxide and the gases arising from the oxidation reaction of carbon monoxide

The 3 isotopic reactions of oxygen: C18O + Ni16O ↔ C16O + Ni18O, 16O18O + Ni16O ↔ 16O2 + Ni18O, and C16O18O + Ni16O ↔ C16O2 + Ni18O between CO, CO2, O2 and NiO are studied using a mass spectrometer. The isotopic gaseous mixtures are prepared from oxygen-18 enriched water. A first order kinetic law has been found for these reactions in the gaseous phase, and the activation energies have been determined. Only CO and CO2 exchange oxygen, at room temperature, but only with part of the oxide surface. Gaseous O2 reacts with the whole surface at 250 C, the slow step of the exchange process, in the gaseous phase, being certainly the mobility of oxygen ions on the surface of NiO. (author)