| abstract |
A process for producing methacrolein and methacrylic acid by oxidizing isobutyl aldehyde with molecular oxygen or molecular oxygen-containing gas in the vapor phase characterized by the use of a catalyst of heteropoly-acid or a mixture of heterpoly-acid and its salt which has the general formula: MoaVbPcXdYeOf wherein Mo, V, P and O represent respectively molybdenum, vanadium, phosphorus and oxygen, X represents one or more elements selected from the group consisting of copper, tin, thorium, aluminum, germanium, nickel, iron, cobalt, zinc, titanium, lead, rhenium, zirconium, cerium, chromium, bismuth and arsenic, Y represents one or more elements selected from the group consisting of potassium, rubidium, cesium and thallium and a, b, c, d, e and f represent the atomic ratio of the elements where, a is 10, b is a number of 6 or less than 6 excluding 0, c is a number of 0.5 to 6, d is a number of 3 or less than 3 excluding 0, e is a number of 0 to 0.8, f is a number determined depending on the valency and atomic ratio of other elements. |