A method for the production of acid anhydrides and a catalyst for the production thereof as well as catalysts which may be used therefor

摘要

Catalysts for the oxidation of hydrocarbons to acid anhydrides, for example maleic and phthalic anhydrides, are prepared from a vanadium/phosphorus mixed oxide precursor by conditioning it by contact with a strong acid of concentration at least 3 N and solvent extraction to remove unwanted phases. The treated precursor is converted to a catalytically active form by heating. Novel catalysts containing phase X are produced. The catalysts may contain rare earth metal promoters.