| 摘要 |
The present invention relates to a process for producing methacrylic acid by oxidizing methacrolein in vapor phase with molecular oxygen or a gas containing molecular oxygen, characterized in that the oxidation is carried out in the presence of a catalyst having a composition shown by the following formula: MoaVbPcXdYeOf wherein Mo, V, P and O respectively represent molybdenum, vanadium, phosphorus and oxygen; X represents at least one element selected from the group consisting of potassium, rubidium, cesium, and thallium; Y represents at least one element selected from the group consisting of copper, silver, tin, thorium, germanium, nickel, iron, cobalt, titanium, rhenium, chromium, cerium, antimony and magnesium; and a, b, c, d, e and f denote the atomic ratio of respective elements where, a is 10, b is a number of 6 or less than 6 excluding 0, preferably 0.5 to 3, c is a number of 0.5 to 6, preferably 0.5 to 3, d is a number of 0.5 or less than 0.5 excluding 0, preferably 0.01 to 0.3, e is a number of 5 or less than 5 exclusing 0, preferably 0.01 to 1 and f is a number determined by the valence and atomic ratio of the other elements and usually is a number of 35 to 80, and comprising heteropolyacid having the elements above-mentioned as its components and X-metal salt of the heteropolyacid both of which are present in a mixed state, and relates also to the above-mentioned catalyst. |
