# US 4,400,368 A · H.sub.2 S Removal process > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,400,368 A - Document ID: US4400368A - Status: Granted - Kind: A - Application number: 06/430,468 - Filed: 1982-09-30 - Granted: 1983-08-23 - Earliest claimed: 1981-11-24 - Assignees: Shell Oil Company - Inventors: Zaida Diaz - Web page: https://patentgrep.com/patent/US4400368A ## CPC - B01D 53/1418: {Recovery of products} - B01D 53/1425: {Regeneration of liquid absorbents} - B01D 53/1462: {Removing mixtures of hydrogen sulfide and carbon dioxide} - B01D 53/1468: {Removing hydrogen sulfide} - B01D 53/1493: {Selection of liquid materials for use as absorbents} - C01B 17/05: by wet processes - Y02C 20/40: of CO2 - Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2 - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG] - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A cyclic process for the removal of hydrogen sulfide, and carbon dioxide, from a variety of gas streams is disclosed. The gas stream containing the sour gas(es) is contacted with an aqueous solution of a specific reactant ligands or chelate, or mixtures thereof, optionally in an absorbent, containing specific stabilizers for improvement of chelate life. The hydrogen sulfide is converted to sulfur, CO.sub.2 may be absorbed to produce a purified gas stream, and the reactant chelate is reduced. The process includes sulfur removal and regeneration of the reactant chelate. ## Claims ### Claim 1 A process for the removal of H.sub.2 S from a sour gaseous stream comprising: (a) contacting the sour gaseous stream in a contacting zone with an aqueous reaction solution at a temperature below the melting point of sulfur, the solution containing an effective amount of a reactant selected from the group consisting of oxidizing polyvalent metal chelate compounds, and mixtures thereof, and a stabilizing amount of a nitrogen-containing composition selected from N,N-diethylhydroxylamine, thiourea, thioemicarbazide, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing crystalline sulfur and a reduced reactant; (b) removing at least a portion of the crystalline sulfur from the aqueous admixture; (c) regenerating the aqueous admixture in a regeneration zone to produce a regenerated reactant; (d) returning aqueous admixture containing regenerated reactant from the regeneration zone to the contacting zone. ### Claim 2 (depends on 1) The method of claim 1 wherein the stream from which the H.sub.2 S is removed is selected from naturally-occurring gases, synthesis gases, process gases and fuel gas. ### Claim 3 (depends on 1) The method of claim 1 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream. ### Claim 4 A process for the removal of H.sub.2 S from a sour gaseous stream comprising: (a) contacting the sour gaseous stream in a contacting zone with an aqueous reaction solution at a temperature below the melting point of sulfur, the solution containing an effective amount of a reactant selected from the group consisting of oxidizing polyvalent metal chelate compounds and mixtures thereof, and a stabilizing amount of a nitrogen-containing composition selected from N,N-diethylhydroxylamine, thiourea, thiosemicarbazide, and mixtures thereof, and producing a sweet gas stream and an aqueous admixture containing crystalline sulfur and a reduced reactant; (b) regenerating the aqueous admixture in a regeneration zone to produce an aqueous admixture containing a regenerated reactant; (c) removing at least a portion of the crystalline sulfur from aqueous admixture from step (b) to produce an aqueous admixture having reduced sulfur content; (d) returning aqueous admixture having reduced sulfur content to the contacting zone. ### Claim 5 (depends on 4) The method of claim 4 having reduced sulfur content wherein the stream from which the H.sub.2 S is removed is selected from naturally-occurring gases, synthesis gases, process gases and fuel gas. ### Claim 6 (depends on 4) The method of claim 4 wherein the sour gaseous stream is selected from natural gas, a stream derived from the gasification of coal, or a hydrocarbon stream. ### Claim 7 A process for the removal of H.sub.2 S and CO.sub.2 from a sour gaseous stream comprising: (a) contacting the sour gaseous stream in a contacting zone at a temperature below the melting point of sulfur with a lean CO.sub.2 -selective absorbent mixture containing an effective amount of a reactant selected from the group consisting of an oxidizing polyvalent metal chelate compounds, and mixtures thereof, and a stabilizing amount of a nitrogen-containing composition selected from N,N-diethylhydroxylamine, thiourea, thiosemicarbazide, and mixtures thereof, and producing a sweet gaseous stream and an absorbent admixture containing absorbed CO.sub.2, crystalline sulfur, and reduced reactant; (b) removing at least a portion of the crystalline sulfur from the absorbent admixture, and leaving a solution containing absorbed CO.sub.2 and reduced reactant; (c) stripping the solution containing absorbed CO.sub.2 and said reduced reactant to remove CO.sub.2, and regenerating said solution, producing a lean CO.sub.2 -selective absorbent solution containing regenerated reactant, and (d) returning lean CO.sub.2 -selective absorbent solution containing regenerated reactant to the contacting zone. ### Claim 8 A process for the removal of H.sub.2 S and CO.sub.2 from a sour gaseous stream comprising: (a) contacting the sour gaseous stream in a contacting zone at a temperature below the melting point of sulfur with a lean CO.sub.2 -selective absorbent mixture containing an effective amount of a reactant selected from the group consisting of oxidizing polyvalent metal chelate compounds, and mixtures thereof, and stabilizing amount of a nitrogen-containing composition selected from N,N-diethylhydroxylamine, thiourea, thiosemicarbazide, and mixtures thereof, and producing a sweet gaseous stream and an adsorbent mixture containing absorbed CO.sub.2, crystalline sulfur, and reduced reactant; (b) stripping the absorbent mixture containing absorbed CO.sub.2, crystalline sulfur, and said reduced reactant, and regenerating said absorbent mixture, producing a lean CO.sub.2 -selective absorbent solution containing a regenerated reactant and sulfur, (c) removing at least a portion of the crystalline sulfur from the lean CO.sub.2 -selective absorbent solution containing the sulfur and the regenerated reactant, and leaving a lean CO.sub.2 -selective absorbent solution containing regenerated reactant, and (d) returning lean CO.sub.2 -selective absorbent solution containing regenerated reactant to the contacting zone, ### Claim 9 (depends on 2) The process of claim 2 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid. ### Claim 10 (depends on 2) The process of claim 2 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of nitrilotriacetic acid. ### Claim 11 (depends on 3) The process of claim 3 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid. ### Claim 12 (depends on 3) The process of claim 3 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of nitrilotriacetic acid. ### Claim 13 (depends on 5) The process of claim 5 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid. ### Claim 14 (depends on 5) The process of claim 5 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of nitrilotriacetic acid. ### Claim 15 (depends on 6) The process of claim 6 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid. ### Claim 16 (depends on 6) The process of claim 6 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of nitrilotriacetic acid. ### Claim 17 (depends on 7) The process of claim 7 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid. ### Claim 18 (depends on 7) The process of claim 7 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of nitrilotriacetic acid. ### Claim 19 (depends on 8) The process of claim 8 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of N-(2-hydroxyethyl)ethylenediamine triacetic acid. ### Claim 20 (depends on 8) The process of claim 8 wherein the oxidizing polyvalent metal chelate compound is the Fe(III) chelate of nitrilotriacetic acid.