Method of preparing butadiene

A method of preparing butadiene, comprising:

• passing a reaction raw materials stream containing butene, oxygen (O2), steam, and butane as a diluent gas through an oxidative dehydrogenation reactor to oxidatively dehydrogenate the butene into oxidative dehydrogenation reaction products containing butadiene, water, n-butane, butene, COx and O2;
• removing water from the oxidative dehydrogenation reaction products by passing the oxidative dehydrogenation reaction products through a cooling separation part;
• condensing hydrocarbons by passing the oxidative dehydrogenation reaction products, from which the water is removed, through a condensation separation part;
• recovering all hydrocarbons not condensed in the condensation separation part by passing the oxidative dehydrogenation reaction products containing hydrocarbons not condensed in the condensation separation part through an absorption separation part;
• and
• separating the butadiene by passing crude hydrocarbons comprising the n-butane, the butene, and the butadiene, which are condensed in the condensation separation part, and crude hydrocarbons comprising the n-butane, the butene, and the butadiene excluding the COx and the O2, which are recovered in the absorption separation part, through a purification part,
• wherein the n-butane and the butene excluding the butadiene, which are separated in the purification part, are fed again into the oxidative dehydrogenation reaction part,
• wherein, in the oxidative dehydrogenation reaction part, the oxidative dehydrogenation is performed in a molar ratio of butene:oxygen:steam:diluent gas=1:0.5 to 3:0.1 to 20:0.1 to 20.