| abstract |
PROBLEM TO BE SOLVED: To provide a gas-phase catalytic oxidation of isobutylene or tertiary butanol with molecular oxygen to suppress a decrease in catalytic function in production of methacrolein and methacrylic acid, thereby enabling long-term operation. SOLUTION: Isobutylene or tertiary butanol is oxidized in contact with a catalyst comprising a composite oxide containing molybdenum, bismuth and iron as essential components to produce methacrolein and methacrylic acid. When the boundary temperature of the activation energy of the reaction for obtaining methacrolein and methacrylic acid is T ° C., the reaction starts at a temperature of (T-3) ° C. or lower, and the reaction is performed while increasing the reaction temperature as the activity of the catalyst decreases. , And at least one activation treatment is performed on the catalyst before the reaction temperature becomes higher than the boundary temperature. |