| abstract |
The invention relates to an absorbent for the selective removal of hydrogen sulfide from a gaseous fluid stream containing an aqueous solution of a) a tertiary alkanolamine; b) a sterically hindered secondary amine of the general formula (I), where R and R independently are selected from C-C C alkyl and C алки-C-hydroxyalkyl; R, R, R and R are independently independently selected from hydrogen, CC-alkyl and CC-hydroxyalkyl, provided 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 CC -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 0.3-0.7; and c) an acid in an amount calculated as a neutralization equivalent relative to the protonated nitrogen atoms in (a) and (b) in the range of 1.0–9.0%, with acid c) selected from inorganic acids selected from phosphoric acid and sulfuric acids, and organic acids selected from phosphonic acids, sulfonic acids, carboxylic acids, tertiary aminocarboxylic acids, N-sec-alkylaminocarboxylic acids and N-tert-alkylaminocarboxylic acids. The preferred amine of formula (I) is 2- (2-tert-butylaminoethoxy) ethanol. The absorbent allows the establishment of a specific HS selectivity at a pressure that is usually present during the purification of natural gas. In addition, the invention relates to a method for removing hydrogen sulfide from a gaseous fluid stream having a partial pressure of HS of at least 0.1 bar and / or a partial pressure of CO at least 0.2 bar, by means of said absorbent. |