| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing a methacrylic acid with good productivity over a long period of time.SOLUTION: In a method of producing a methacrylic acid by oxidizing methacrolein with oxygen using a continuous system, after a mixture gas containing methacrolein, 300-3,000 volume ppm of isobutylene and oxygen is supplied and oxidation is started so that a methacrolein conversion rate in a reactor exit becomes at least 85%, the oxidation is continued while supplying the mixture gas wherein the isobutylene content is 300-3,000 volume ppm until a difference (X1-X2) between a methacrolein conversion rate (X2) in the reactor exit and the methacrolein conversion rate (X1) in the reactor exit at the start of the oxidation becomes any of 2-30%, and after the difference (X1-X2) becomes any of 2-30%, the oxidation is continued while supplying the mixture gas wherein the isobutylene content is ≤500 volume ppm. |
