Kinetics of the Oxidation of Reduced Mo-V-Phosphoric Heteropoly Acid Species with Dioxygen in Concentrated Aqueous Solutions
Reaction Kinetics and Catalysis Letters
, E-ISSN: 1588-2837
||Dioxygen, Heteropoly acids
Boreskov Institute of Catalysis, Pr. Ak. Lavrentieva 5, Novosibirsk 630090, Russia
Concentrated (0.2 M) aqueous solutions of HP-acids, such as H3+x+mPVIVmVVx-mMo12-xO40 and their analogues with an excess VO2+ cation, are oxidized by dioxygen at 343 K and atmospheric pressure through intermediate active complexes (IAC) [Hx+m-1PVIVmVVx-mMo12-xO404-] · [VO2+]y · O2, where m + y ≥ 3. The electron transfer to the coordinated O2 molecule inside AC is the limiting stage at high m. At low m, the formation of IAC becomes the limiting stage that results in a sharp decrease in the oxidation rate.