Process for the removal of H.sub.2 S and CO.sub.2 from a gas mixture

A process for the removal of H.sub.2 S and CO.sub.2 from a gaseous feed mixture and preparation of a gas with a H.sub.2 S concentration suitable to be used in a Claus process, which process comprises:

• (a) countercurrently contacting said gaseous feed mixture at elevated pressure in a first absorption zone with a lean absorbent solution comprising the mixture of a tertiary amine, sulfolane and water, therein producing an unabsorbed portion and a first loaded absorbent solution;
• (b) passing said first loaded absorbent solution to a flashing zone maintained at a pressure below the total partial pressure of the CO.sub.2 and H.sub.2 S present in said first loaded absorbent solution at the temperature present in said flashing zone, therein effecting the liberation of a gaseous stream containing a portion of said CO.sub.2 and H.sub.2 S present in said first loaded absorbent solution and producing a semi-loaded absorbent solution;
• (c) countercurrently contacting said gaseous stream from step (b) with a lean absorbent solution comprising the mixture of a tertiary amine, sulfolane and water in a second absorption zone under conditions which are selective for H.sub.2 S removal, therein producing a CO.sub.2 -rich unabsorbed gaseous stream and a second loaded absorbent solution;
• (d) passing a portion of said first loaded absorbent solution to a regeneration zone, therein regenerating said first loaded absorbent and producing a lean absorbent solution;
• (e) passing said second loaded absorbent solution to a regeneration zone, therein regenerating said second loaded absorbent and producing a lean absorbent solution;
• (f) stripping at least a portion of said semi-loaded absorbent solution from step (b) with said CO.sub.2 -rich unabsorbed gaseous stream from step (c) in a stripping zone, therein producing a stripped gaseous stream and a stripped absorbent stream;
• (g) passing said stripped absorbent stream to said first absorption zone at a point between where said gaseous feed mixture enters said first absorption zone and where said lean absorbent solution enters said first absorption zone;
• (h) concurrently contacting said stripped gaseous stream from step (f) with a lean absorbent solution comprising the mixture of a tertiary amine, sulfolane and water in a third absorption zone under conditions which are selective for H.sub.2 S removal, therein producing an unabsorbed gaseous stream and a third loaded absorbent solution;
• and
• (i) passing said third loaded absorbent solution to a regeneration zone, therein regenerating said third loaded absorbent and producing a lean absorbent solution.