Method for regenerating phosphorus-molybdenum-alkali containing oxidation catalyst

摘要

A method for regenerating a spent oxidation catalyst useful in the production of unsaturated carboxylic acids by vapor-phase oxidation of unsaturated aldehydes, the catalyst containing, at least, phosphorus, molybdenum, and an alkali metal(s), which method comprises dissolving and/or suspending the spent catalyst in a liquid composition, wherein the contents of ammonium ion and nitrate ion are controlled to be from 7 to 15 moles and from 0.1 to 4.0 moles, respectively, per 12 gram atoms of molybdenum, and immediately thereafter mixing the spent catalyst and the liquid composition.