Method for regenerating heteropolyacid catalyst and method for producing methacrylic acid

摘要

The invention provides a method for regenerating with high efficiency a deteriorated catalyst of reduced activity, said catalyst originating from a heteropolyacid catalyst containing heteropolyacid formed of molybdophosphoric acid and/or molybdovanadophosphoric acid, or a salt thereof, to a heteropolyacid catalyst which exhibits approximately equivalent activity level to that of the fresh catalyst. Said method comprises mixing a deteriorated catalyst and a nitrogen-containing heterocyclic compound under the conditions whereunder ammonium ions and nitrate anions are present at such ratio that the amount of total ammonium ions per mol of total nitrate anions does not exceed 1.7 mols, drying the mixture and calcining the same.