abstract |
C4 vanadium - phosphorus oxidation catalysts for producing maleic acid are prepared in an aqueous phosphoric acid solution using a reducing agent comprising an organic acid or aldehyde and a secondary alcohol such as oxalic acid and ethanol in a mole of 1:1 to 3 respectively, in which an inorganic vanadium compound such as V2O5 is dissolved and reduced to vanadium of 5<+> valency or less. |