Removal of aromatic hydrocarbons from lean acid gas feed for sulfur recovery

A process for the removal of aromatic hydrocarbons, such as benzene, toluene, ethyl benzene and xylene (BTX) and aliphatic hydrocarbons having 4 carbon atoms or more (C4+) from a lean acid gas containing CO2 and less than 20 mol. % of H2S, which process comprises:

• a) contacting the lean acid gas stream (1) with a H2S-selective liquid absorbent solution (29) in a first absorption zone (2) to produce a gas stream depleted in H2S (3) and containing CO2, aromatic hydrocarbons and C4+ aliphatic hydrocarbons, and an absorbent solution enriched in H2S (4), also containing co-absorbed C4+ aliphatic hydrocarbons, aromatic hydrocarbons and CO2,
• b) introducing the absorbent solution enriched in H2S (4) into a non-thermic stripping zone (8) where it is contacted with a stripping gas stream (7), preferably fuel gas, to obtain an absorbent solution depleted in C4+ aliphatic hydrocarbons and aromatic hydrocarbons (9) and containing H2S and CO2 and a stripping gas stream enriched in aromatic hydrocarbons and C4+ aliphatic hydrocarbons (10), also containing H2S and CO2,
• c) contacting the stripping gas stream enriched in aromatic hydrocarbons and C4+ aliphatic hydrocarbons (10), also containing H2S and CO2 obtained in step b) with a H2S-selective liquid absorbent solution (28) in a second absorption zone (12) to obtain a stripping gas stream depleted in H2S and containing aromatic hydrocarbons, C4+ aliphatic hydrocarbons and CO2 (13), and an absorbent solution enriched in H2S (14) also containing co-absorbed aromatic hydrocarbons, C4+ aliphatic hydrocarbons and CO2, said H2S-selective liquid absorbent solution being preferably identical to that used in step a),
• d) introducing the absorbent solution depleted in C4+ aliphatic hydrocarbons and aromatic hydrocarbons (9) obtained in step b) into a desorption zone (16) wherein the H2S-selective liquid absorbent solution (17) is recovered and a lean acid gas containing H2S and CO2, depleted in C4+ aliphatic hydrocarbons and aromatic hydrocarbons (21) is produced.