Abstract: A process for treating a hydrogen sulfide-containing hydrogenated Claus process tail gas to convert the hydrogen sulfide to elemental sulfur in which said gas is contacted with an aqueous alkaline solution containing a water-soluble metal vanadate, a water-soluble anthraquinone disulfonate, and a water-soluble, inorganic fluoride, borate, or phosphate complexing agent to yield an effluent gas to reduced sulfur content. The solution is thereafter regenerated by contact with an oxygen-containing gas, elemental sulfur is recovered from the solution, and the regenerated solution is recycled to the gas-contacting step. The complexing agent contained in the solution reduces the chemical consumption of the anthraquinone disulfonate.

Abstract: A process for treating a hydrogen sulfide-containing hydrogenated Claus process tail gas to convert the hydrogen sulfide to elemental sulfur in which said gas is contacted with an aqueous alkaline solution containing a water-soluble metal vanadate, a water-soluble anthraquinone disulfonate, and a water-soluble phenolic complexing agent or a water-soluble carboxylic complexing agent, to yield an effluent gas of reduced sulfur content. The solution is thereafter regenerated by contact with an oxygen-containing gas, elemental sulfur is recovered from the solution, and the regenerated solution is recycled to the gas-contacting step. The complexing agent contained in the solution reduces the chemical consumption of the anthraquinone disulfonate.

Abstract: A process for treating a hydrogen sulfide-containing hydrogenated Claus process tail gas to convert the hydrogen sulfide to elemental sulfur in which said gas is contacted with an aqueous alkaline solution containing a water-soluble metal vanadate, a water-soluble anthraquinone disulfonate, and a water-soluble, inorganic fluoride, borate, or phosphate complexing agent to yield an effluent gas of reduced sulfur content. The solution is thereafter regenerated by contact with an oxygen-containing gas, elemental sulfur is recovered from the solution, and the regenerated solution is recycled to the gas-contacting step. The complexing agent contained in the solution reduces the chemical consumption of the anthraquinone disulfonate.

Abstract: A process for treating a hydrogen sulfide-containing feed gas, deficient in thiocyanate ion precursors, to convert the hydrogen sulfide to elemental sulfur in which said gas is contacted with an aqueous alkaline washing solution containing a water-soluble metal vanadate, and a water-soluble anthraquinone disulfonate to yield an effluent gas of reduced sulfur content. Thiocyanate ion precursors are added to the solution to reduce the chemical consumption of the anthraquinone disulfonate. The solution is thereafter regenerated by contact with an oxygen-containing gas; elemental sulfur is recovered from the solution; and the regenerated solution is recycled to the gas-contacting step.

Abstract: The consumption of anthraquinone disulfonate by oxidation, employed in the Stretford process which treats hydrogen sulfide-containing gases to yield a sulfur-free effluent gas and elemental sulfur, is reduced by the addition of a chemical precursor to the solution which increases the thiosulfate ion concentration of the solution.