Method for producing conjugated diolefin

A method for producing a conjugated diolefin, the method comprising:

• feeding a monoolefin having four or more carbon atoms and an oxygen-containing gas into a fluidized bed reactor having an oxide catalyst containing molybdenum therein, and bringing the oxide catalyst, the monoolefin having four or more carbon atoms, and the oxygen-containing gas into contact with each other to produce a conjugated diolefin,
• wherein at least 50% or more of a total amount of the oxygen-containing gas is fed from an oxygen-containing gas feed nozzle located at a bottom of the fluidized bed reactor,
• wherein the monoolefin having four or more carbon atoms is fed from a plurality of monoolefin feed nozzles installed at n places located at heights a1, a2, . . . , and an from the oxygen-containing gas feed nozzle, respectively,
• wherein the plurality of monoolefin feed nozzles at the heights a1, a2, . . . , and an feed the monoolefin having four or more carbon atoms at ratios of b1, b2, . . . , and bn, respectively, based on a total amount of the monoolefin having four or more carbon fed into the fluidized bed reactor such that b1+b2+ . . . +bn=1, and
• wherein a weighted mean value represented by the following formula is 100 mm or greater:
• weighted mean value=a1*b1+a2*b2+ . . . +an*bn.