Patent ID: 8916117

Claim:
A method for operating an acid gas treatment unit with reduced corrosion by the in situ generation of polysulfide ions comprising: (a) contacting an acid gas stream containing H 2 S with an aqueous alkaline absorbent solution to absorb the H 2 S into the solution to form a process stream including HS and/or S 2 -ions; and (b) subjecting the stream containing the HS- and/or S 2 -ions to electrochemical oxidation to oxidize the HS- and/or S2-ions to generate polysulfide ions, and (c) regenerating the aqueous alkaline absorbent solution to release acid gas components from the solution; wherein the aqueous alkaline absorbent solution is contained in an acid gas treatment unit having a metal surface which the polysulfide ions contact to form metal-polysulfide on the metal surface to ameliorate corrosion of the metal surface.