Removal of acid gases from a gas mixture

Claim 1

A process for the selective removal of H 2 S from a gas mixture containing H 2 S and CO 2 , comprising: (a) contacting in a first contact zone at elevated pressure the gas mixture with a lean and regenerable absorbent, from which zone purified gas mixture and a first loaded absorbent containing H 2 S and CO 2 are removed; (b) heating the first loaded absorbent and flashing in a separating vessel at reduced pressure a substantially CO 2 -containing off-gas including a minor amount of H 2 S from the first loaded absorbent, from which separating vessel off-gas and partly loaded absorbent are removed; (c) contacting in a second contact zone the off-gas with a lean and regenerable absorbent that selectively absorbs H 2 S, from which zone an almost H 2 S-free CO 2 -containing gas mixture and a second loaded absorbent are removed; (d) adding the second loaded absorbent to the first loaded absorbent in the separating vessel or upstream of the heating in step (b); (e) introducing the partly loaded absorbent from steps (b) and (d) into a regeneration zone and obtaining a regenerated absorbent used as the lean and regenerable absorbent in steps (a) and (c), and a substantially H 2 S-containing gas mixture.