| abstract |
An absorbent for the selective removal of hydrogen sulfide from a fluid stream comprises an aqueous solution a) of a tertiary amine, b) a sterically hindered secondary amine of the general formula (I) wherein R 1 and R 2 are each independently selected from C 1-4 alkyl and C 1-4 hydroxyalkyl; R 3 , R 4 , R 5 and R 6 are each independently selected from hydrogen, C 1-4 alkyl and C 1-4 hydroxyalkyl, with the proviso that at least one of R 4 and R 5 on the carbon atom which is bonded directly to the nitrogen atom, is C 1-4 alkyl or C 1-4 hydroxyalkl, when R 3 is hydrogen; x and y are integers from 2 to 4 and z is an integer from 1 to 4; wherein the molar ratio of b) to a) in the range of 0.05 to 1.0 and c) an acid in an amount, calculated as neutralization equivalents based on the protonatable nitrogen atoms in a) and b), from 0.05 to 15.0%. A preferred amine of the formula I is 2- (2-tert-butylaminoethoxy) ethanol. The absorbent allows the adjustment of a defined H 2 S selectivity at pressures typically present in natural gas processing. |