Production process of 1,3-butadiene
A process of producing 1,3-butadiene includes: a first step of obtaining gases containing 1,3-butadiene by an oxidative dehydrogenation reaction of a raw material gas with a molecular oxygen-containing gas in the presence of a metal oxide catalyst, the raw material gas containing 1-butene and 2-butene and having a proportion of 2-butene to a sum of 1-butene and 2-butene, which is defined as 100% by volume, being not less than 50% by volume; a second step of cooling the produced gases obtained in the first step; and a third step of separating the produced gases having undergone the second step into molecular oxygen and inert gases and other gases containing 1,3-butadiene by selective absorption to an absorbing solvent, wherein the concentration of methyl vinyl ketone in the produced gases having been cooled in the second step is 0% by volume or more and not more than 0.03% by volume.
1. A process of producing 1,3-butadiene, the process comprising:
conducting an oxidative dehydrogenation reaction of a raw material gas with a molecular oxygen-containing gas in the presence of a metal oxide catalyst, thereby obtaining gases comprising 1,3-butadiene, the raw material gas comprising 1-butene and 2-butene and having a proportion of 2-butene to a stun of 1-butene and 2-butene, which is defined as 100% by volume, being not less than 50% by volume;
cooling the gases; and
separating cooled gases into molecular oxygen and inert gases and other gases comprising 1,3-butadiene by selective absorption to an absorbing solvent,
wherein a concentration of methyl vinyl ketone in the cooled gases is 0% by volume or more and not more than 0.03% by volume,
wherein a first pressure in the conducting is not less than 0.1 MPaG and not more than 0.4 MPaG,
wherein a second pressure in the cooling is not more than the first pressure, and
wherein a third pressure in the separating is not more than the second pressure.
2. The process of claim 1 , wherein, in the cooled gases:
a concentration of molecular nitrogen is not less than 60% by volume and not more than 94% by volume,
a concentration of the sum of 1-butene and 2-butene is 0% by volume or more and not more than 2% by volume,
a concentration of 1,3-butadiene is not less than 2% by volume and not more than 15% by volume, and
a concentration of ketones and aldehydes is 0% by volume or more and not more than 0.3% by volume.
3. The process of claim 1 , wherein, in the cooling, the gases are cooled by being brought into contact with a cooling medium, and a concentration of an organic acid in the cooling medium having been in contact with the gases is not more than 7% by mass.
4. The process of claim 1 , wherein the first pressure in the conducting is not less than 0.15 MPaG and not more than 0.4 MPaG.
5. The process of claim 1 , wherein the molecular oxygen and inert gases is flown back to the conducting, and
wherein a concentration of molecular nitrogen in the gases to be flown back from the separating to the cooling is not less than 87% by volume and not more than 97% by volume, and a concentration of the molecular oxygen therein is not less than 1% by volume and not more than 6% by volume.
6. The process of claim 1 , wherein the first pressure in the conducting is not less than 0.2 MPaG and not more than 0.4 MPaG.
7. The process of claim 1 , wherein the first pressure in the conducting is not less than 0.1 MPaG and not more than 0.35 MPaG.
8. The process of claim 1 , wherein the first pressure in the conducting is not less than 0.1 MPaG and not more than 0.3 MPaG.
9. The process of claim 1 , wherein the first pressure in the conducting is not less than 0.2 MPaG and not more than 0.3 MPaG.
10. The process of claim 1 , wherein a concentration of the sum of the 1-butene and the 2-butene in the raw material gas is not less than 75% by volume.
11. The process of claim 1 , wherein a concentration of the sum of the 1-butene and the 2-butene in the raw material gas is not less than 95% by volume.
12. The process of claim 1 , wherein the proportion of 2-butene to a sum of 1-butene and 2-butene in the raw material gas is not less than 75% by volume.
13. The process of claim 1 , wherein the proportion of 2-butene to a sum of 1-butene and 2-butene in the raw material gas is not less than 87% by volume.
14. The process of claim 1 , wherein a difference in pressure between the separating to the cooling is 0 MPaG or more and not more than 0.05 MPaG.
15. The process of claim 1 , wherein a difference in pressure between the separating to the cooling is 0.01 MPaG or more and not more than 0.04 MPaG.
16. The process of claim 1 , wherein the raw material gas comprises not more than 25% by volume impurities, per 100% by volume of the raw material gas.
17. The process of claim 1 , wherein the raw material gas comprises not more than 5% by volume impurities, per 100% by volume of the raw material gas.
18. The process of claim 1 , wherein the concentration of the methyl vinyl ketone in the cooled gases is 0% by volume or more and not more than 0.028% by volume.
19. The process of claim 1 , wherein the concentration of the methyl vinyl ketone in the cooled gases is 0% by volume or more and not more than 0.008% by volume.
20. The process of claim 1 , wherein the absorbing solvent is not less than 10 times by mass and not more than 100 times by mass, relative to a mass flow rate of the sum of the butadiene, 1-butene, and 2-butene in gases produced after the cooling.