Catalytic removal of hydrogen sulfide from gases

Claim 1

In a continuous catalytic oxidation-reduction process for the removal of hydrogen sulfide gas from a gaseous stream by contacting the gaseous stream with an aqueous solution containing an iron chelate catalyst having iron in the ferric state adapted to oxidize the hydrogen sulfide to elemental sulfur and be reduced to the ferrous state, separating said elemental sulfur from said solution, and regenerating said solution by contacting said solution with an oxygen containing gas to convert the ferrous iron to the ferric state; the improvement which comprises; (a) contacting the gaseous stream containing said hydrogen sulfide with an aqueous solution of chelated iron containing at least two iron chelating agents with at least one of said iron chelating agents being selected from the group of amines consisting of polyamino polycarboxylic acids, polyamino alkyl polycarboxylic acids, polyamino hydroxyalkyl polycarboxylic acids, and poly(phosphonoalkyl) amines, and their alkali metal salts and another of said iron chelating agents being selected from the group of polyhydroxy compounds consisting of monosaccharides, disaccharides, reduced monosaccharides, reduced disaccharides, monosaccharide acids, disaccharide acids, and their alkali metal salts; and (b) said solution having a pH ranging between about pH 5.5 and about pH 13.