CATALYTIC VAPOR-PHASE OXIDATION METHOD

PROBLEM TO BE SOLVED: To provide a simple catalytic vapor-phase oxidation reaction for decreasing a hot spot. SOLUTION: In catalytic vapor-phase oxidation reaction by a multitubular reactor where a heating medium 10 is made to circulate into a reactor shell 1 through a circulator 30 joining circular conduits 11a and 11b, the vapor-phase oxidation reaction features that a part of the heating medium 10 taken out from the shell 1 is heat-exchanged and also a heating medium inlet 32 for receiving the heat-exchanged heating medium is located near a heating medium cycling port 31 of the circulator 30 or is the circular conduit 11b. It is preferable that an amount of the heat-exchanged heating medium is in the range of 2-40 vol.% based on the amount of the heating medium in the reactor shell and difference in temperature between the heating media existing in the inlet and the outlet is 15-150 deg.C. Thus, hot spot in the reactor can uniformly be decreased, and therefore the catalytic vapor-phase oxidation reaction of propylene or isobutylene can be carried out in such as way that an objective reaction product is obtained in a good yield.