Abstract: A method of removing hydrogen sulfide from a gaseous stream in a contact zone by contacting the gaseous stream with an aqueous alkaline scrubbing solution containing a polyvalent metal chelate at a pH of about 7 to about 10 wherein the polyvalent metal chelate is in one embodiment all or substantially all in the reduced or lower valence state in a contact zone and is oxidized to the oxidized or higher valence state in an oxidation zone so as to convert hydrosulfide and/or sulfide salts present in the contact zone to sulfur. In a second embodiment the aqueous alkaline solution contacting the gaseous stream is a mixture containing higher and lower valence polyvalent metal chelates.

Abstract: A continuous process for removing hydrogen sulfide from a gas stream by contacting the gas stream with a solution of ammonium hydroxide to produce an effluent liquid stream comprising ammonium sulfide which is fed to a heating zone maintained at least at the boiling temperature of said solution and supplied with an oxygen containing gas sparge wherein ammonia and hydrogen sulfide are removed from said zone as vapor and sulfur is removed from said zone as an aqueous dispersion, the sulfur being separated in a filtration zone from the residual aqueous liquid which is recycled back to a contact zone together with said ammonia and said hydrogen sulfide vapor.

Abstract: A process for removing hydrogen sulfide from a gaseous stream containing hydrogen sulfide by contacting said stream with an aqueous solution of ammonium hydroxide to produce ammonium sulfide; converting said ammonium sulfide to an ammonium polysulfide intermediate in an electrolytic cell at ambient temperature and pressure; and oxidizing said ammonium polysulfide to sulfur in a heating zone utilizing an oxygen containing gas sparge.