| abstract |
The present invention relates to an absorbent for selectively removing hydrogen sulfide from a fluid stream containing an aqueous solution of a) a tertiary amine, b) a sterically hindered secondary amine of general formula (I), where R and R are respectively independently selected from C-C-alkyl and CC- hydroxyalkyl; R, R, R and R are independently independently selected from hydrogen, C-C-alkyl and C-C-hydroxyalkyl with the proviso that at least one residue R 5 and / or R on the carbon atom that is directly attached to the nitrogen atom means CC -alkyl or C-C-hydroxyalkyl, if R is hydrogen; x and y are integers 2-4, and z is an integer 1-4; moreover, the molar ratio of b) to a) is in the range of 0.3-0.7, and c) acid in an amount calculated as the equivalent of neutralization relative to the protonated nitrogen atoms in a) and b) in the range of 1.0-9.0 % One preferred amine of formula I is 2- (2-tert-butylaminoethoxy) ethanol. The absorbent allows the establishment of a certain selectivity for HS at a pressure that is usually present during the purification of natural gas. In addition, the present invention relates to a method for removing acid gases from a fluid stream having a partial pressure of HS of at least 0.1 bar and / or a partial pressure of a cobalt of at least 0.2 bar, by means of said absorbent. |