Recent Advances in Regeneration of Aqueous Low‐Vanadium Mo–V‐Phosphoric Heteropoly Acid Solutions with O2

At present, the aqueous solutions of low‐vanadium Mo−V‐phosphoric heteropoly acids (HPA‐1 and HPA‐2) are widely used in various areas of catalysis owing to their oxidizing ability. It has been shown that in the presence of concentrated acetic acid the reduced solutions of these HPAs can be almost completely oxidized with oxygen at high reaction rate at a temperature below 100 °C and atmospheric pressure. This opens broad prospects for the development of new catalytic oxidation technologies in the presence of low‐vanadium heteropoly acid solutions as reversible oxidants. At present, there are no efficient methods to oxidize the reduced forms of heteropoly acids H3+xPMo12‐xVxO40 with x of 1–2 (HPAs) that possess a great potential as homogeneous oxidation catalysts. Addition of acetic acid was found to ensure an efficient and almost full regeneration of such aqueous solutions at 70 °C under atmospheric pressure that opens new application areas of HPAs.