METHOD FOR PRODUCING 1,3-BUTADIENE
The present invention has as its object the provision of a method for producing 1,3-butadiene capable of efficiently purifying an absorption solvent while a high productivity is assured. A method for producing 1,3-butadiene includes: a step (A) of obtaining a produced gas containing 1,3-butadiene; a step (B) of cooling the produced gas; a step (C) of separating the produced gas, which has been subjected to the step (B); a step (D1) of separating the absorption solvent, that has absorbed an absorption component comprising the other gases containing 1,3 -butadiene into an absorption solvent that does not substantially contain the absorption component and an absorption solvent that contains the absorption component; a step (D2) of separating the absorption solvent that contains the absorption component into an absorption solvent that contains a reaction by-product and a 1,3-butadiene liquid; and a step (E) of purifying the absorption solvent, that contains the reaction by-product.
1 . A method for producing 1,3-butadiene comprising:
a step (A) of performing an oxidative dehydrogenation reaction, with a molecular oxygen-containing gas in a presence of a metal oxide catalyst, of a raw material gas, which contains n-butene, to obtain a produced gas containing 1,3-butadiene;
a step (B) of cooling the produced gas obtained in the step (A);
a step (C) of separating the produced gas, which has been subjected to the step (B), into molecular oxygen and inert gases, and other gases containing 1,3-butadiene by selective absorption into an absorption solvent; and
a step (D) of separating the absorption solvent, which has been obtained in the step (C), that has absorbed the other gases containing 1,3-butadiene, to obtain a 1,3-butadiene liquid, containing 1,3-butadiene, and the absorption solvent, wherein
the step (D) includes:
a step (D1) of separating the absorption solvent, which has absorbed the other gases containing 1,3-butadiene, into an absorption solvent that does not substantially contain an absorption component including the other gases containing 1,3-butadiene and an absorption solvent that contains the absorption component;
a step (D2) of separating the absorption solvent, which has been obtained in the step (D1), that contains the absorption component into an absorption solvent that contains a reaction by-product and the 1,3-butadiene liquid containing 1,3-butadiene; and
a step (E) of purifying the absorption solvent, which has been obtained in the step (D2), that contains the reaction by-product.
2 . The method for producing 1,3-butadiene according to claim 1 , wherein:
the absorption solvent, which has been obtained in the step (D1), that does not substantially contain the absorption component and the purified absorption solvent that has been obtained in the step (E) are returned to the step (C), and
concentrations of ketones and aldehydes in the absorption solvent returned from the steps (D1) and (E) to the step (C) are 0% by mass or more and not more than 1% by mass.
3 . The method for producing 1,3-butadiene according to claim 1 , wherein in the step (D), an amount of the absorption solvent, which is subjected to the step (D1), that has absorbed the other gases containing 1,3-butadiene is larger than an amount of the absorption solvent, which is subjected to the step (D2), that contains the absorption component.
4 . The method for producing 1,3-butadiene according to claim 2 , wherein in the step (D), an amount of the absorption solvent, which is subjected to the step (D1), that has absorbed the other gases containing 1,3-butadiene is larger than an amount of the absorption solvent, which is subjected to the step (D2), that contains the absorption component.