Diamine having tert-alkylamino group and primary amino group for use in gas scrubbing
A compound of the general formula (I) in which R 1 , R 2 and R 3 are independently selected from C 1-4 -alkyl and C 1-4 -hydroxyalkyl; each R 4 is independently selected from hydrogen, C 1-4 -alkyl and C 1-4 -hydroxyalkyl; each R 5 is independently selected from hydrogen, C 1-4 -alkyl and C 1-4 -hydroxyalkyl; m is 2, 3, 4 or 5; n is 2, 3, 4 or 5; and o is an integer from 0 to 10. A preferred compound of the formula (I) is 2-(2-tert-butylaminoethoxy)ethylamine. Absorbents comprising a compound of the formula (I) have rapid absorption of carbon dioxide from fluid streams and are also suitable for processes for the simultaneous removal of H 2 S and CO 2 , where given H 2 S limits have to be observed but complete removal of CO 2 is not required.
1. An absorbent for removing carbon dioxide and/or hydrogen sulfide from fluid streams, comprising an aqueous solution of a compound of the general formula (I)
in which R 1 and R 3 are each independently selected from C 1-4 -alkyl and C 1-4 -hydroxyalkyl;
each R 4 is independently selected from hydrogen, C 1-4 -alkyl and C 1-4 -hydroxyalkyl;
each R 5 is independently selected from hydrogen, C 1-4 -alkyl and C 1-4 -hydroxyalkyl;
m is 2, 3, 4 or 5;
n is 2, 3, 4 or 5; and
o is an integer from 1 to 10.
2. The absorbent according to claim 1 , with the proviso that the R 5 radical on the carbon atom bonded directly to the primary amino group is hydrogen.
3. The absorbent according to claim 1 , wherein the absorbent comprises at least one organic solvent.
4. The absorbent according to claim 1 , wherein the absorbent comprises at least one acid.
5. The absorbent according to claim 1 , wherein the concentration of the compound of the formula (I) in the absorbent is 10% to 60% by weight.
6. The absorbent according to claim 1 , also comprising at least one tertiary amine and/or a sterically hindered primary or secondary amine.
7. The absorbent according to claim 6 , wherein the tertiary amine is methyldiethanolamine.
8. A process for removing carbon dioxide and/or hydrogen sulfide from fluid streams, the process comprising:
contacting an absorbent according to claim 1 with a fluid stream, to obtain a CO 2 - and H 2 S-depleted fluid stream and a CO 2 - and H 2 S-laden absorbent.
9. The process according to claim 8 , wherein the fluid stream comprises at least one hydrocarbon.
10. The process according to claim 8 , wherein the fluid stream has a total pressure of at least 3.0 bar.
11. The process according to claim 8 ,
further comprising: regenerating the CO 2 - and H 2 S-laden absorbent,
wherein said regenerating comprises at least one of heating, decompressing and stripping the absorbent with an inert fluid.
12. A compound of the general formula (Ia)
in which R 1 , R 2 and R 3 are each independently selected from C 1-4 -alkyl and C 1-4 -hydroxyalkyl;
each R 4 is independently selected from hydrogen, C 1-4 -alkyl and C 1-4 -hydroxyalkyl;
each R 5 is independently selected from hydrogen, C 1-4 -alkyl and C 1-4 -hydroxyalkyl; and
m is 2, 3, 4 or 5.
13. The compound according to claim 12 , with the proviso that the R 5 radical on the carbon atom bonded directly to the primary amino group is hydrogen.
14. The compound according to claim 13 , which is 2-(2-tert-butylaminoethoxy)ethylamine.