# US 7,608,231 B2 · Process for the continuous removal of hydrogen sulfide from gaseous streams > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,608,231 B2 - Document ID: US7608231B2 - Status: Granted - Kind: B2 - Application number: 12/065,909 - Filed: 2006-08-31 - Published: 2008-12-04 - Granted: 2009-10-27 - Earliest claimed: 2005-09-07 - Assignees: ENI S.p.A. - Inventors: Giuseppe Bellussi; Alberto De Angelis; Paolo Pollesel; Marcello Milli - Web page: https://patentgrep.com/patent/US7608231B2 ## CPC - B01D 53/14: by absorption - B01D 53/1418: {Recovery of products} - B01D 53/1425: {Regeneration of liquid absorbents} - B01D 53/1468: {Removing hydrogen sulfide} - B01D 53/1493: {Selection of liquid materials for use as absorbents} - C01B 17/05: by wet processes - C10L 3/10: Working-up natural gas or synthetic natural gas - 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} - C10L: FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G OR C10K; LIQUIFIED PETROLEUM GAS; USE OF ADDITIVES TO FUELS OR FIRES; FIRE-LIGHTERS ## Abstract Process for the removal in continuous of hydrogen sulfide from gaseous streams containing it, comprising: a) putting a gas containing H2S in contact with an oxidizing acid aqueous solution of ferric nitrate and containing a heteropolyacid having redox properties; b) filtrating and separating the sulfur produced by the redox reaction; c) oxidizing the ferrous nitrate to ferric nitrate with air; d) recycling the solution containing ferric nitrate and heteropolyacid to the oxidation step (a); e) subjecting the gaseous stream leaving the oxidation reactor (c) to washing with the reduced solution; and f) discharging the gaseous stream. ## Claims ### Claim 1 A process for the continuous removal of hydrogen sulfide from a gaseous stream containing hydrogen sulfide, comprising: a) putting a gas containing H2S in contact with an oxidizing acidic aqueous solution of ferric nitrate which further comprises a heteropolyacid having redox properties, as such or partially salified with an alkaline metal or with ammonium, selected from those having general formula (I): HnXVyM(12-y)O40, (I) wherein n is an integer ranging from 3 to 6; X is selected from P, Si, As, B, and Ge; y is an integer ranging from 1 to 3; and M is selected from Mo and W; b) filtering and separating sulfur produced in a) as a result of the oxidizing effect of the ferric nitrate, which is reduced to ferrous nitrate in solution with heteropolyacid; c) oxidizing the ferrous nitrate from b) to ferric nitrate with air in an oxidation reactor thereby producing a solution comprising ferric nitrate and heteropolyacid; d) recycling the solution comprising ferric nitrate and heteropolyacid from d) to redox (a); e) subjecting a gaseous stream comprising one or more nitrogen oxides leaving the oxidation reactor in (c), to washing in a washing apparatus to the head of which is fed from 10 to 100% by weight of the reduced solution coming from sulfur separation (b), before the same is fed to the oxidation (c); and f) discharging the gaseous stream. ### Claim 2 (depends on 1) The process according to claim 1, wherein said heteropolyacid is used in a solid form which is insoluble in water and is selected from: a partial or complete salification with metals, whose salts are insoluble, selected from cesium, ammonium, potassium, silver and thallium(I); one supported and immobilized on silica; one supported and immobilized on mesoporous molecular sieves; and one supported and immobilized on activated carbon. ### Claim 3 (depends on 1) The process according to claim 1, wherein the gaseous stream consists of natural gas or an associated gas coming from a production well. ### Claim 4 (depends on 1) The process according to claim 1, wherein the ferric nitrate is present in the oxidizing solution in concentrations ranging from 0.01 to 3 moles/l. ### Claim 5 (depends on 1) The process according to claim 1, wherein the heteropolyacid compound (I) is present in concentrations ranging from 0.01 to 0.5 moles/l. ### Claim 6 (depends on 1) The process according to claim 1, wherein the molar ratio heteropolyacid compound (I)/ferric nitrate ranges from 1/1 to 1/100. ### Claim 7 (depends on 1) The process according to claim 1, wherein the acid aqueous solution has a pH ranging from 0 to 6. ### Claim 8 (depends on 1) The process according to claim 1, wherein the hydrogen sulfide is present in the gas fed in a concentration ranging from 0.01 to 100% by volume. ### Claim 9 (depends on 1) The process according to claim 1, wherein the oxidation step (c) takes place at a temperature ranging from 20 to 100° C. and at atmospheric pressure or a value higher than atmospheric pressure, up to 50 atmospheres. ### Claim 10 (depends on 1) The process according to claim 1, wherein the redox reaction (a) and oxidation reaction (c) and the washing phase (e) are effected in bubble, filled or plate columns. ### Claim 11 (depends on 1) The process according to claim 1, wherein the oxidation reaction (c) and the washing phase (e) are effected in a single column wherein the washing column overlies the oxidation column and operates at a temperature lower than or equal to the oxidation column. ### Claim 12 (depends on 3) The process according to claim 3, wherein the pressure in the redox reactor ranges from 1 atmosphere to the pressure of the production well.