Catalytic oxidation method and method for producing conjugated diene

A method of performing a catalytic oxidation reaction in a tubular reactor in the presence of a molybdenum composite oxide catalyst, the method comprising:

• arranging a molybdenum compound layer containing a molybdenum compound and a composite oxide catalyst layer containing a molybdenum composite oxide catalyst in this order from a reaction raw material supply port side of the tubular reactor;
• and
• feeding a raw material comprising an organic compound into the tubular reactor,
• wherein the molybdenum compound layer supplies molybdenum to the composite oxide catalyst layer,
• wherein the catalytic oxidation reaction comprises an oxidative dehydrogenation reaction for producing, from the organic compound under a reaction temperature, an oxidative dehydrogenation reaction product corresponding to the organic compound,
• wherein a temperature of the molybdenum compound layer at the time of the catalytic oxidation reaction is lower by 3 to 50° C. than a temperature of the catalyst layer,
• wherein the temperature of the molybdenum compound layer at the time of catalytic oxidation reaction is lower by greater than 0° C. to 40° C. than the reaction temperature,
• wherein the molybdenum compound comprises molybdenum oxide and an alkali metal or an alkaline earth metal, and
• wherein, under a flow of a mixed gas at 440° C. composed of a composition containing 75 vol % of air and 25 vol % of water vapor, a molybdenum sublimation amount (μg/NL) of the molybdenum compound is larger than a molybdenum sublimation amount (μg/NL) of the molybdenum composite oxide catalyst.