Ion Cyclotron Resonance Study of CO Oxidation in the Gas Phase in the Presence of Rhenium Cations with Carbonyl and Oxygen Ligands. Comparison with Heterogeneous Catalysis
Gas-phase oxidation of CO in the presence of rhenium cations with carbonyl and oxygen ligands has been studied by Fourier transform ion cyclotron resonance (FT-ICR) spectrometry. Rhenium cations have been generated by the electron impact of Re2(CO)10 vapour. Contrary to the unreactive rhenium ions, rhenium monocarbonyl ions have been found to react with 02 molecules yielding rhenium monoxide ions and CO2 molecules. ReO+ ions are subsequently oxidized with 02 to di-and trioxide ions. The bond energies in rhenium oxide ions were estimated as D0 =104 4-14, D0 118,D0 +- O) = 122 :k 4 kcal/m01. Simultaneous addition of CO and Oz molecules to the reaction volume leads to the gas-phase catalytic oxidation of CO with pairs of rhenium oxide ions ReO~-/ReO + serving as the oxidized and reduced forms of the catalyst. The mechanisms of the above reactions are discussed in connection with that for oxidation of CO over solid oxide catalysts.
