PREPARATION OF CATALYST FOR PREPARING METHACRYLIC ACID

摘要

PURPOSE:To obtain the catalyst for preparing methacrylic acid having low temp. activity and long life by a method wherein an ammonium ion containing stock solution is concentrated to dryness and the obtained substance is subjected to final baking in a specific temp. range in an inert gas. CONSTITUTION:In preparating a catalyst comprising heteropolyacid having a general formula PaMobVcXdYeOf (wherein X is K, Ce or the like, Y is Cu, Fe or the like, a is 0.1-6, b is 12, C is 0-6, d is 0-3, e is 0-6) or a salt thereof, an ammonium ion is contained in a stock solution and, after the obtained mixed solution is concentrated to dryness, final baking is carried out at 400-500 deg.C in an inert gas of which oxygen concn. is below 5vol%. In preparing methacrylic acid by subjecting methacrolein to contact oxidation by molecular oxygen in a gas phase, this catalyst lowers reaction temp. and keeps activity thereof for a long period of time.