Method for producing conjugated diene

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

• subjecting a raw material gas comprising a monoolefin having a carbon atom number of 4 or more to an oxidative dehydrogenation with a gas comprising molecular oxygen in the presence of a catalyst to obtain a reaction product gas comprising a conjugated diene;
• and
• subjecting the reaction product gas to a cooling stop;
• wherein, in the cooling step, a cooling agent is supplied into a cooling column and is brought into contact with the reaction product gas,
• the cooling agent discharged from the cooling column is then cooled by a condenser,
• a precipitate precipitated by cooling is recovered by at least one separation apparatus, and
• the cooling agent from which the precipitate has been recovered is circulated into the cooling column;
• wherein the cooling agent is water;
• wherein the condenser is heat exchanger, and a liquid linear rate in the condenser is faster than 1.0 m/sec;
• wherein the cooling column comprises an upper zone and a lower zone which are separated by a chimney, and
• the upper zone and the lower zone each comprise at least one tray;
• and
• wherein, in the cooling column, the reaction product gas is introduced to the lower zone,
• a mixture comprising a portion of the reaction product gas and the cooling agent is discharged from a bottom of the upper zone above the chimney,
• the mixture is directed through the at least one separation apparatus to obtain a cooled mixture, and
• the cooled mixture from which the precipitate has been recovered is directed to a top of the upper zone of the cooling column.

A method for producing a conjugated diene the method comprising:

• subjecting a raw material gas comprising a monoolefin having a carbon atom number of 4 or more to an oxidative dehydrogenation reaction with a gas comprising molecular oxygen in the presence of a catalyst, to obtain a reaction product gas comprising a conjugated diene;
• and
• subjecting the reaction product gas to a cooling step;
• wherein water is used as a cooling agent;
• wherein, in the cooling step, the cooling agent is supplied into a cooling column and is brought into contact with the reaction product gas, and the cooling agent discharged from the cooling column is then cooled by at least one heat exchanger and circulated into the cooling column;
• wherein the cooling column comprises an upper zone and a lower zone which are separated by a chimney, and
• the upper zone and the lower zone each comprise at least one tray;
• wherein, in the cooling column, the reaction product as is Introduced to the lower zone,
• a mixture comprising a portion of the reaction product gas and the cooling agent is discharged from a bottom of the upper zone above the chimney,
• the mixture is directed through the at least one heat exchanger and through at least one separation apparatus to obtain a cooled mixture, and
• the cooled mixture from which the precipitate has been recovered is directed to a top of the upper zone of the cooling column;
• and
• by regulating a liquid linear rate of the cooling agent passing through the at least one heat exchanger to 1.0 m/sec or less, 9-fluorenone is accumulated within the at least one heat exchanger, and the 9-fluorenone is separated from the cooling agent, or
• by making a liquid linear rate of the cooling agent passing through the at least one heat exchanger faster than 1.0 m/sec to pass through the at least one heat exchanger, the 9-fluorenone is then separated from the cooling agent by the at least one separation apparatus.