| abstract |
PROBLEM TO BE SOLVED: To produce methacrylic acid with high selectivity and high yield by subjecting isobutane to catalytic gas phase oxidation. SOLUTION: As a catalyst, a catalyst containing (i) a sparingly water-soluble salt of a heteropoly acid and (ii) a composite oxide containing phosphorus, molybdenum and vanadium is used. The component (i) has, for example, an elemental composition (excluding oxygen) represented by the following general formula (1). AaBbMocWd Ve (1) (where A represents a counter cation and at least one selected from potassium, rubidium, cesium and thallium) B represents a central element of the heteropolyacid, and at least one element selected from silicon, phosphorus and arsenic; o, W and V represent molybdenum, tungsten and vanadium, respectively, which are the coordinating atoms of the heteropolyacid; a, b, c, d and e represent the atomic ratio of each component, and b = When 1, a = 3-4, c = 0-12, d = 0-12, e = 0-3, c + d + e = 12. ) |