Process for increased selectivity and capacity for hydrogen sulfide capture from acid gases
A process for selectively separating H 2 S from a gas mixture which also comprises CO 2 is disclosed. A stream of the gas mixture is contacted with an absorbent solution comprising one or more amines, alkanolamines, hindered alkanolamines, capped alkanolamines, or mixtures thereof. The H 2 S/CO 2 selectivity of the absorbent solution is preferably greater than about 4.0 for an acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] between about 0.2 and about 0.6, and is achieved by reducing pH of the absorbent solution.
1. A process for selectively separating H 2 S from a gas mixture which also comprises CO 2 , the process comprising:
contacting a stream of the gas mixture with an absorbent solution comprising methoxyethoxyethoxyethanol-t-butylamine (M3ETB);
wherein the M3ETB concentration in the absorbent solution is between 20 and 30 wt %.
2. The process of claim 1 , wherein the M3ETB concentration in the absorbent solution is between 25 and 30 wt %.
3. The process of claim 1 , wherein the H 2 S/CO 2 selectivity of the absorbent solution is greater than about 5.0 over the entire acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] range between 0.2 and 0.55.
4. The process of claim 1 , wherein the H 2 S/CO 2 selectivity of the absorbent solution is greater than about 6.0 over the entire acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] range between 0.2 and 0.55.
5. The process of claim 1 , wherein the H 2 S/CO 2 selectivity of the absorbent solution is greater than about 7.0 over the entire acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] range between 0.2 and 0.55.
6. A process for selectively separating H 2 S from a gas mixture which also comprises CO 2 , the process comprising:
contacting a stream of the gas mixture with an absorbent solution comprising methoxyethoxyethoxyethanol-t-butylamine (M3ETB);
wherein the M3ETB concentration in the absorbent solution is between 25 and 30 wt %.
7. The process of claim 6 , wherein the H 2 S/CO 2 selectivity of the absorbent solution is greater than about 5.0 over the entire acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] range between 0.2 and 0.55.
8. The process of claim 6 , wherein the H 2 S/CO 2 selectivity of the absorbent solution is greater than about 6.0 over the entire acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] range between 0.2 and 0.55.
9. The process of claim 6 , wherein the H 2 S/CO 2 selectivity of the absorbent solution is greater than about 7.0 over the entire acid gas loading [mol(CO 2 +H 2 S)/mol(amine)] range between 0.2 and 0.55.