| abstract |
An absorbent for the selective removal of hydrogen sulfide from a fluid stream comprises an aqueous solution of a) a tertiary amine, b) a secondary amine with steric hindrance of the general formula (1) in which R¹ and R² are selected each one independently of C₁₋₄ alkyl and C₁₋₄ hydroxyalkyl; R³, R⁴, R⁵ and R⁶ are each independently selected from hydrogen, C₁₋₄ alkyl and C₁₋₄ hydroxyalkyl, with the proviso that at least one radical R⁴ and / or R⁵ in the carbon atom attached directly to the atom Nitrogen is C₁₋₄ alkyl or C₁₋₄ hydroxyalkyl when R³ is hydrogen; x e y are integers from 2 to 4 and z is an integer from 1 to 4; where the molar ratio of b) aa) is in the range of 0.05 to 1, and c) an acid in an amount, calculated as neutralization equivalent to the protonable nitrogen atoms in a) and b), of 0.05 to 15%. A preferred amine of the formula (1) is 2- (2-tert-butylaminoethoxy) ethanol. The absorbent allows to establish a defined H definidaS selectivity at the pressures of the typical class of natural gas processing. |