Patent ID: 8197778

Claim:
A method for removing sulfur dioxide (SO 2 ) from carbon dioxide feed gas comprising SO 2 as a contaminant, said method comprising: maintaining said carbon dioxide feed gas, or a SO 2 -lean carbon dioxide gas derived therefrom, at elevated pressure(s) in a sour gas reactor system in the presence of oxygen (O 2 ), water and NO x for a period of time sufficient to convert SO 2 to sulfuric acid condensate and NO x to nitric acid condensate; separating said acid condensates from said carbon dioxide gas to produce SO 2 -depleted, NO x -lean carbon dioxide gas; and neutralizing at least a portion of said sulfuric acid condensate by reaction with an alkaline sorbent in an acid/sorbent reactor system to produce sorbent-derived sulfate, wherein said sour gas reactor system comprises at least one stage operating at elevated pressure and said acid/sorbent reactor system operates at a lower pressure than said elevated pressure, said lower pressure being at least 2 bar, said method comprising depressurizing said sulfuric acid condensate produced at said stage to produce reduced pressure sulfuric acid condensate and desorbed carbon dioxide gas at said lower pressure; and feeding said reduced pressure sulfuric acid condensate to said acid/sorbent reactor system.