Method of vapor phase catalytic oxidation using multitubular reactor

A method of a vapor phase catalytic oxidation of a substance to be oxidized with a gas containing molecular oxygen by means of a multitubular reactor, the multitubular reactor comprising:

• a cylindrical reactor shell fitted with a raw material supply port and a product outlet;
• multiple circular conduits disposed around the cylindrical reactor shell and used to introduce a heat medium into the cylindrical reactor shell or to lead the heat medium out therefrom;
• a circulation device for connecting the multiple circular conduits to each other;
• multiple reaction tubes restrained by means of multiple tube plates of the reactor and having a catalyst accommodated therein;
• and multiple baffles arranged in a longitudinal direction of the reaction tube and used to change a direction of the heat medium introduced into the reactor shell, wherein the method comprises:
• performing a reaction of vapor phase catalytic oxidation under such conditions that a heat transfer coefficient of the heat medium is 1,000 W/(m2·K) or higher, and preventing the reaction of vapor phase catalytic oxidation in an area of the reactor having a heat transfer coefficient of the heat medium less than 1,000 W/(m2·K).