Abstract: A method of removing hydrogen sulfide from a sour gaseous stream in a contact zone by contacting the sour gaseous stream with a H.sub.2 S selective absorbent in an aqueous alkaline solution containing a polyvalent metal chelate at a pH of about 7 to about 10 wherein the polyvalent metal chelate is in one embodiment of the invention 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 absorbed hydrogen sulfide, hydrosulfide and/or sulfide salts present in the contact zone to sulfur. In a second embodiment, the aqueous alkaline solution and H.sub.2 S selective absorbent in contact with the gaseous stream is a mixture containing a higher valence polyvalent metal chelate together with a lower valence polyvalent metal chelate.

Abstract: Water-in-oil emulsions containing by weight about:20 to 80% of a dispersed aqueous phase containing about 20 to 70% of one or more aldehydes chosen from the group constituted by formaldehyde, glyoxal, glutaraldehyde, glycolaldehyde or glyoxylic acid and 80 to 30% of an aqueous solution containing 90 to 100% water and 10 to 0% of a buffer agent pH=5.5.+-.1.5; and 80 to 20% of a continuous oil phase containing about 90 to 99 % of one or more saturated and liquid C.sub.6 -C.sub.16 hydrocarbons, and 10 to 1% of an emulsifying system constituted by one or more water-in-oil emulsifying agents and process for the elimination of hydrogen sulphide.

Abstract: A method for purifying flue-gasses and other hot, oxidative waste gasses originating from industrial installations, combustion furnaces, engines and the like, whereby the hot gas to be purified is passed through at least one spraying chamber or -area and is contacted therein with a gas washing liquid, which is sprayed into the hot gas flow and cools the gas to below 100.degree. C., whereby residual liquids with a high C.Z.V.-value, which comprise complex builders, compounds of heavy metals, sulphur- and nitrogen compounds, and originating amongst others from fixing-baths and the like from the photographic, photochemical and galvanic industries, are used as gas washing liquid.

Abstract: Components, usually but not exclusively gaseous components, are removed in a liquid medium from gas streams and chemically converted into an insoluble phase or physically removed. Specifically, hydrogen sulfide may be removed from streams by oxidation in aqueous chelated transition metal solution in a modified agitated flotation cell. A gas-liquid contact apparatus, generally a combined chemical reactor and solid product separation device, comprising such modified agitated flotation cell also is described. In order to effect efficient mass transfer and rapid reaction, gas bubbles containing hydrogen sulfide and oxygen are formed by rotating an impeller at a blade tip velocity of at least about 350 in/sec. to achieve the required shear. To assist in the reaction, a surrounding shroud has a plurality of openings, generally of aspect ratio of approximately 1, of equal diameter and arranged in uniform pattern, such as to provide a gas flow therethrough less than about 0.02 lb/min/opening in the shroud.

Abstract: The corrosion and fouling of metal surfaces in contact with corrosive acid fluids or acid salts in the presence of an aqueous medium is reduced by contacting the surfaces with a composition which comprises (a) an anti-fouling amount of a hydroxyl amine compound of the formulaR.sub.1 R.sub.2 N--OHwherein R.sub.1 and R.sub.2 are independently hydrogen or a hydrocarbyl or inertly substituted hydrocarbyl or both R.sub.1 and R.sub.2 are collectively a divalent hydrocarbyl combined with said nitrogen to form a heterocyclic ring, and (b) a corrosion-inhibiting amount of a reaction product of or a mixture for the purpose of a reaction product of a polyalkylene polyamine and an alkynediol. The polyalkylene polyamine is one that contains from 2-10 amine groups, each separated from another by an alkylene group having from 2-6 carbon atoms. The alkynediol has from 2 to 6 carbon atoms.

Abstract: A process for removal of H.sub.2 S from gas streams is described, the process being characterized by use of a novel iron chelate treating solution containing a specified ferric to ferrous chelate ratio, aqueous ammonia, and thiosulfate ion.

Abstract: A process for removal of H.sub.2 S from gas streams is described, the process being characterized by use of a novel iron chelate treating solution containing a specified ferric to ferrous chelate ratio and aqueous ammonia.

Abstract: For regenerating a scrubbing agent loaded with H.sub.2 S and/or COS, as well as optionally with other raw gas components to be recovered, the loaded scrubbing agent is mixed, preferably without prior heating, with an oxidatively acting solvent that is immiscible with the scrubbing agent, and the H.sub.2 S dissolved in the immiscible solvent is converted to elementary sulfur.

Abstract: A method for reducing the hydrogen sulfide content of hydrocarbon-containing fluids and aqueous solutions through a two-stage injection procedure whereby a dilute solution of a scavenging agent is injected into a hydrogen sulfide-containing fluid, followed by equilibration and a second injection of dilute solution of scavenging agent to further reduce the hydrogen sulfide content of the treated fluid.

Abstract: The long term stability of process solutions used in H.sub.2 S-to-sulfur absorption/oxidation process, wherein the incoming hydrogen sulfide-containing gas stream is contaminated with hydrocarbons and/or organic oxygenated compounds and the process is generating an excessive amount of thiosulfate in the process solution, is improved by a method comprising contacting the gas stream and/or the process solution with charcoal to remove both the contamination and at least a portion of the thiosulfate therefrom.

Abstract: A process for removal of H.sub.2 S from sour gaseous streams by use of an aqueous reactant solution is described in which the sour gaseous stream is employed as the motive force to transport the solution during the contact phase of the process, at the same time the static head of the aqueous reactant solution in the reservoir is used to provide the solution in the reservoir to the reaction zone entrance.

Abstract: A process for the removal of H.sub.2 S from sour gaseous streams is disclosed in which the sour gaseous stream is contacted with a solution containing solubilized iron chelates of a specified organic acid or acids. The contacting is carried out in first and second contacting zones, the first being a gas-solution mixture formation zone and the second comprising a plurality of contacting sections adapted to provide reaction of the H.sub.2 S in the sour gaseous stream with the iron in the contacting solution without plugging due to deposition of sulfur.

Abstract: In the processing of a geothermal brine and the recovery of heat therefrom, there are produced a non-condensable gas stream containing hydrogen sulfide and carbon dioxide and a liquid stream comprising a condensate of steam derived from the brine. In accordance with the present invention, the noncondensable gases are introduced into the condensate in the presence of an oxidizing agent to form a gas-liquid mixture. The mixture is maintained at an alkaline pH for a time sufficient for a substantial portion of the hydrogen sulfide to be oxidized. Thereafter, the mixture is introduced into a gas-liquid separation zone for separate recovery of a gas stream comprising a major amount of carbon dioxide and substantially free of hydrogen sulfide. Advantageously, the recovered gas stream is recycled to the geothermal brine process to reduce the pH of the brine and its scaling potential.

Abstract: A process for scavenging hydrogen sulfide from gases, in which the hydrogen sulfide-containing gas is introduced into an aqueous glyoxal solution of at least 15% by weight strength at a pH of a solution of 5 to 11 until the molar ratio of glyoxal to hydrogen sulfide is 3 to 2. The solid reaction product obtained in this way, which contains the hydrogen sulfide in bound form, is separated off. Owing to its stability and insolubility in acids and bases, it can be disposed of without problems.

Abstract: A process is provided for controlling the emission of hydrogen sulfide from, and the growth of living organisms in, steam condensate cooling towers and catch basins used in conjunction with steam and condensate of steam derived from hydrogen sulfide-containing geothermal brine. The process comprises contacting the condensate, in a substantially continuous manner, with a small, substantially less-than-stoichiometric amount of an oxidizing biocide, such as trichloro-isocyanuric acid or oxidizing biocide, such as trichloro-isocyanuric acid or 1-bromo-3-chloro-5,5-dimethyl-hydantoin, which results in the oxidation of such hydrogen sulfide precursors as ammonium bisulfide in the condensate to a water-soluble sulfite and/or sulfate, and which slows the growth of organisms in the cooling tower and catch basin.

Abstract: Hydrogen sulfide is removed from a fluid stream of condensed steam by addition of an iron chelate catalyst to oxidize H.sub.2 S to sulfur. The removal is carried out in a modified cooling tower where condensed steam is added to a recycled iron chelate liquid in a water collection tray for a period of time sufficient to oxidize the H.sub.2 S before the fluid stream is introduced to the cooling tower to remove sulfur.

Abstract: An aqueous fluid for treating underground, carbon dioxide-containing formations penetrated by casing regions of a wellbore, prior to the cementing of casings into the wellbore, comprises: (i) water, (ii) an agent which substantially increases (preferably by at least about 50 percent) the solubility of lime in water, and (iii) lime in an amount at least about saturating the water in the fluid. The lime in the treatment fluid reacts with carbon dioxide in penetrated formations to produce insoluble calcium carbonate, which blocks pores in the formations. Insoluble calcium hydroxide, formed by reaction of the lime with the water in the treatment fluid, deposits as an insoluble filter cake on the walls of the borehole where the fluid penetrates formations. The calcium hydroxide filter cake may react with the carbon dioxide to form additional calcium carbonate which helps the filter cake form a tight, impermeable barrier at the borehole.

Abstract: Vent gas from the condenser-scrubber system of a reactor, in which dithionites are made by reacting a formate, sulfur dioxide, and an alkali in aqueous methanol, is reduced in its ethylene oxide content to less than 10 ppm maintaining the ratio of sulfur dioxide to ethylene oxide entering the scrubber to greater than 1.0, preferably greater than 2.5, and most preferably greater than 3.0 and at a temperature of -20.degree. C. to 0.degree. C.

Abstract: An improved aqueous catalytic oxidation-reduction composition for oxidizing hydrogen sulfide to produce elemental sulfur and a method of removing hydrogen sulfide from a gas stream whereby a gas stream containing hydrogen sulfide is brought into contact with an aqueous catalytic oxidizing reaction composition containing a water soluble polyvalent metal salt having metal in the highest valence state and at least one nonionic surfactant having an HLB of from about 8 to about 10, preferably about 8.5 to about 9, which is adapted to wet the elemental sulfur formed. The nonionic surfactant is present in the reaction solution in an amount sufficient to substantially prevent formation of sulfur froth at the surface of the reaction solution and to cause the sulfur to precipitate as a granular solid that can be recovered by filtration, by centrifucation, or other similar means.

Abstract: This invention provides a process for removing H.sub.2 S from the gaseous stream by contacting the stream with an aqueous solution of a water soluble oxidized polyvalent metal chelate catalyst in the presence of oxygen whereby the metal chelate catalyst oxidizes the hydrogen sulfide to produce elemental sulfur and the oxygen present oxidizes the reduced metal chelate catalyst to its oxidized form. This process is performed in a single reaction vessel and forms a suspension or slurry of the precipitated elemental sulfur which is maintained in suspension by the use of a dispersing agent. The process is continued until the sulfur content reaches a level of 5 percent by weight or 10 percent or more by weight of the solution, then the entire solution is discarded and replaced with a fresh solution and the process repeated. This invention also provides a composition for H.sub.2 S removal comprising a polyvalent metal chelate catalyst, a buffer and a dispersing agent.

Abstract: A method and arrangement for facilitating removal of hydrogen sulfide from a combuation process gas includes provision of a packed bed scrubber having packing material therein comprising a polymeric substance having an outer surface with a substantially hydrophilic character. For preferred arrangements and methods, the packing material comprises a polymeric substance having a plurality of sulfonic acid groups, or neutralized sulfonic acid groups, thereon. A method of providing such packing material comprises reaction of a substantially hydrophobic packing material with sulfur trioxide. Preferred scrubber arrangements utilizing segmented packing beds are also disclosed. The result of the described methods and processes is a scrubber arrangement having a substantially reduced propensity for plugging, by comparison to conventional scrubber arrangements, when utilized for otherwise conventional scrubbing processes.

Abstract: Gases containing CO.sub.2 and/or H.sub.2 S in a first absorption stage, at from 40.degree. to 100.degree. C., with an aqueous absorption liquid containing from 20 to 79% by weight of methyldiethanolamine, the gas obtained at the top of the first absorption stage is fed to a second absorption stage in which, it is treated at from 30.degree. to 90.degree. C. with an aqueous absorption liquid which contains from 20 to 79% by weight of methyldiethanolamine and has a lower content of CO.sub.2 and/or H.sub.2 S than the absorption liquid fed into the first absorption stage, the treated gas is taken off at the top of the second absorption stage, the aqueous absorption liquid obtained at the bottom of the second absorption stage and preladen with CO.sub.2 and/or H.sub.2 S is fed to the top of the first absorption stage, the aqueous absorption liquid obtained in the lower part of the first absorption stage and laden with CO.sub.2 and/or H.sub.

Abstract: Methods are disclosed for selectively reducing the levels of hydrogen sulfide and oragnic sulfides from gaseous and/or liquid hydrocarbon streams, particularly natural gas streams, compromising contacting the streams with a composition comprising the reaction product of (i) a lower alkanolamine with (ii) a lower aldehyde.

Abstract: A process of removing hydrogen sulfide from a gas stream in which the hydrogen sulfide is dissolved in an absorption zone by a solvent having a good solvent power for hydrogen sulfide and a much greater solvent power for sulfur dioxide. The resultant solution is divided into a major stream and a minor stream. The major stream is contacted with a small excess of sulfur dioxide over that required for reaction with hydrogen sulfide. Most of this solution is recycled to the absorption zone. The minor stream withdrawn from the absorption zone is mixed with the solution formed in the reaction zone which is not recycled, the proportion being such that there remains a small excess of hydrogen sulfide in solution. This solution is then stripped of hydrogen sulfide. By this means only a small fraction of the solution has to be stripped. Preferred solvents are those which promote the reaction of hydrogen sulfide with sulfur dioxide.

Abstract: The present invention is a process for reversibly absorbing acid gases, such as CO.sub.2, H.sub.2 S, SO.sub.2, HCN and the like from gas mixtures. The gas mixture containing one or more of these acid gases is contacted with a hydrated salt of the compositionA.sub.x.sup.m+ B.sub.y.sup.n-.rH.sub.2 Owherein A.sup.m+ is a cation, B.sup.n- is the conjugate base of a weak acid having a pKa corresponding to an ionization constant of the acid greater than 3 as measured in dilute aqueous solution, m and n are independently integers from 1-4, x and y are integers such that the ratio of x to y provides a neutral salt and r is any number greater than zero up to the maximum number of moles of water which can be bound to the salt. The salt hydrate reversibly absorbs the acid gas from the gas mixture.

Abstract: An integrated system for the derivation of useful energy from impure steam and/or use in connection therewith, said steam containing both hydrogen sulfide and an alkaline acting component, such as ammonia, while producing liquid-phase and gaseous-phase effluents from condensation of the impure steam and substantially reducing the emission of sulfur-containing compounds to the environment. Treatment of such effluents to selectively react or bind alkaline acting components in the liquid-phase results in an augmented concentration of hydrogen sulfide in the gaseous-phase and its depletion in the liquid-phase. The gaseous-phase comprising noncondensable gas contaminants and uncondensed water vapor is separated from the liquid-phase steam condensate and treated to remove hydrogen sulfide to produce an environmentally acceptable vent gas which may be discharged to the atmosphere.

Abstract: A preheater assembly for softening a selected portion of plastic stock material prior to severing and edge sealing is disclosed. The preheater assembly includes a pair of opposed preheaters, each having a heater tip connected to a source of heated air. The air flows through the tip to maintain it at a preselected temperature. The preheaters are mounted on opposite sides of the stock material for motion toward the material to engage it on opposite sides to heat and soften it, and away from the material to release it. Clamp elements engage the stock material during the heating and softening process.

Abstract: A process for abating hydrogen sulfide during geothermal steam stacking operations is disclosed. The geothermal steam to be stacked is introduced into a geothermal steam stacking line. Ferric chelating solution is injected into the stacking line in an amount effective to convert the hydrogen sulfide in the steam to sulfur. The hydrogen sulfide-abated steam and chelating solution is vented through a rock muffler and the chelating solution is optionally recovered from the muffler, regenerated and recirculated to the injection step.

Abstract: In a process for cleaning, cleaning a packed column utilized in a gas scrubbing operation wherein the packing is obstructed by solids formed during the scrubbing step, the obstructions are removed in a maximally economical fashion and without interrupting of normal operation. The packed column contains at least n, wherein n>1, superimposed packed beds spatially separated from one another. During cleaning, the lowermost up to maximally the (n-1)th packed bed are flooded with scrubbing agent. Preferably, the packed column is used for scrubbing H.sub.2 S out of a feedgas mixture with an oxidative scrubbing agent wherein sulfur is formed during the scrubbing operation and deposited in the packed beds.

Abstract: Processes for the removal of hydrogen sulphide from gas streams and for the regeneration of spent scrubbing liquor used in an absorber to remove hydrogen sulphide from a gas stream, are disclosed. In the former process, hydrogen sulphide is removed by five-valent oxovanadium which is simultaneously reduced to its four-valent state, the precipitation of which is prevented by having a sufficiently high concentration of total alkalinity present in the scrubbing solution. In the latter process the four-valent oxovanadium is oxidized to its five-valent state, preferably by an oxygen-containing gas, and a suffficently high concentration of total alkalinity is provided in the scrubbing liquor to yield a desired re-oxidation rate of the four-valent oxovanadium.

Abstract: Hydrogen sulphide is removed from gas streams in rapid and efficient manner by oxidation to sulphur. The process is effected by intimately contacting the hydrogen sulphide in the gas stream with oxygen in an aqueous medium containing a hydrogen sulphide-oxidizing catalyst to effect oxidation of the hydrogen sulphide to sulphur, and transporting the sulphur particles to the surface of the aqueous medium. The sulphur particles collect on the surface of the aqueous medium and may be removed therefrom continuously or intermittently.

Abstract: Disclosed are primary sterically hindered aminoacids for use as promoters for alkali metal salts in acid gas scrubbing. The primary sterically hindered aminoacid is selected from 1-amino-cyclopentane carboxylic acid and those represented by the formula: ##STR1## where R.sub.1 and R.sub.2 are independently selected from CH.sub.3, C.sub.2 H.sub.5, and C.sub.3 H.sub.7 ; R.sub.3 and R.sub.4 are independently selected from hydrogen and CH.sub.3 ; and n is 0, 2, or 3.

Abstract: A method is provided for removing elemental sulfur particles from a hydrogen sulfide removal process which employs a regenerable, aqueous washing solution capable of absorbing hydrogen sulfide from an industrial gas stream and converting that hydrogen sulfide to elemental sulfur. The washing solution of such a process is contacted with bubbles of an oxygen-containing gas while in the presence of an effective amount of a cationic sulfur particle-size increasing polymeric flocculent to form a sulfur-containing froth from which the sulfur is recovered.

Abstract: Hydrogen sulphide is removed using transition metal carboxylates.

Abstract: A process for oxidizing a metal from a lower valence state to a higher valence state comprises contacting the metal, usually contained in a solution, with a sufficient amount of an oxygen-containing gas to provide at least about 300% excess of stoichiometric oxygen with respect to the metal at the lower valence state. The metals are preferably used as chelated solutions thereof. Some of the representative metals are iron, copper, manganese, lead or mercury.

Abstract: A process for purifying an aqueous, hydrogen sulfide-scrubbing solution which contains a water-soluble transition metal component, such as a vanadium component or an iron component, in addition to at least one water-soluble organic compound, such as an aromatic sulfonate or an alkanolamine, in which the scrubbing solution is mixed with particles of a spent solid catalyst containing molybdenum and aluminum and a basic aqueous solution, preferably a solution comprising sodium aluminate, to form a slurry which is subsequently contacted with an oxygen-containing gas under conditions such that the molybdenum in the catalyst is solubilized. Thereafter, molybdenum is precipitated from the solution along with the water-soluble transition metal component and a wastewater substantially free of the transition metal component and the organic compound originally present in the scrubbing solution is recovered.

Abstract: The present disclosure is directed to a process in solution for removing H.sub.2 S from a stream of natural gas. Sodium nitrite in the solution serves as an oxidizing agent for the H.sub.2 S. Buffering and defoaming agents are added. Absent a catalyst, the process suffers from conversion of the nitrite ion into NH.sub.3 which conversion is suppressed by the incorporation of a transition metal chelate complex. The metal is preferably chromium, copper or iron and the chelate complex is preferably EDTA or TEA, with acceptable performance obtained from HEEDTA or NTA. The metal chelate complex catalyzes the sodium nitrite oxidation of H.sub.2 S, markedly enhancing sulfur recovery as a precipitate in solution.

Abstract: A process and apparatus for the removal of H.sub.2 S from sour gaseous streams is disclosed in which the sour gaseous stream is contacted with an aqueous reactant solution containing solubilized iron chelates. The contacting is carried out in first and second contacting zones, the first being a continuous liquid phase mixture formation zone and the second comprising a plurality of contacting sections adapted to provide reaction of the H.sub.2 S in the sour gaseous stream with the iron in the contacting solution by producing an upwardly flowing continuous liquid phase mixture comprising sour gas dispersed in the aqueous reactant solution.

Abstract: Gas containing sulfide is washed in the washing vessel (13) with a washing liquid that normally comprises an alkaline solution having sodium 1,4-naphthoquinone-2-sulfonate as the catalyst. Contaminated liquid is subjected in a pressure vessel (59) to aeration under pressure with air or pure oxygen. By oxidation, elementary sulfur precipitates out and this is filtered out continuously in the filter (77). Regenerated washing liquid flows via a degassing vessel (69) into the storage container (27) and from there returns to the washing vessel (13). In the degassing vessel, under relaxed pressure, degassing occurs, and the sulfur foam along with the oxygen or air it contains is returned via the pump (55) to the presure vessel (59) or to the filter (77).

Abstract: A process for removal of H.sub.2 S from gas streams is described, the process being characterized by use of a novel iron chelate treating solution containing a specified ferric to ferrous chelate ratio, aqueous ammonia, and thiosulfate ion.

Abstract: The present invention relates to a cyclic continuous process and a composition for the removal of hydrogen sulfide from a variety of sour gas streams. The sour gas stream is contacted with an aqueous solution of a water-soluble organic polymeric chelate containing an oxidizing polyvalent metal, e.g., Fe(III). The sulfur in the hydrogen sulfide is converted to elemental sulfur and the iron in the polymeric chelate is reduced. The process includes removal of the elemental sulfur, and an inexpensive method for removing water and excess low molecular weight materials, e.g., materials having molecular weights below 500, preferably using ultrafiltration or dialysis regeneration and recycle of the reactive polyvalent metal.

Abstract: A process for removal of H.sub.2 S from gas streams is described, the process being characterized by use of a novel iron chelate treating solution containing a specified ferric to ferrous chelate ratio and aqueous ammonia.

Abstract: A process for the selective removal of sulfur-containing gases from industrial gases or waste gases by treatment of gases with basic substances, characterized in that the basic substances are carrier materials containing tertiary amino groups corresponding to the following formula: ##STR1## in which m and n individually are 1 or 2,x and y individually are from 0 to 10 and preferably 0 to 2,R and R' individually are hydrogen or alkyl andR" is hydrogen or methyl.

Abstract: Excess water is removed from regenerated redox solution by contacting a downwardly flowing spray of regenerated redox solution with a stream of inert gas at a rate and pressure sufficient to provide for the substantial saturation of the gas with excess water impurities in the redox solution without the substantial undesirable oxidation of the metal in the regenerated redox solution.

Abstract: A process and formulation are provided for the removal of sulfides from solids and fluids utilizing certain halonitroalkanols. These compounds can rapidly and quantitatively remove hydrogen sulfide, organic sulfides and their salts from solutions, particularly aqueous mixtures.

Abstract: A process for the removal of H.sub.2 S from sour gaseous streams is disclosed, the process being characterized by the use of solutions containing vanadium V-containing ions and phosphate ions in sufficient amount to convert the H.sub.2 S to elemental sulfur. The process may be cyclic, allowing for continuous operation. A composition suitable for use in the process is also disclosed.

Abstract: Electrochemical regeneration in an electrochemical cell of spent scrubbing solutions containing polvalent metal chelates is accomplished without substantial degradation of the chelate by controlling the anolyte pH and maintaining the anode potential of the cell above the oxidation potential of the polyvalent metal chelate but below the oxidation potential of the chelate portion of the polyvalent metal chelate.

Abstract: Fluid streams containing hydrogen sulfide from a steam tubine or from a sour gas stream are contacted with an aqueous solution of a polyvalent metal chelate and a bisulfite whereby the hydrogen sulfide is converted to free sulfur and then to soluble sulfur compounds. The metal chelate is reduced to a lower oxidation state metal chelate and reduced metal chelate is subsequently oxidized with air back to the higher oxidation state and reused. The bisulfite is formed by combustion of a portion of the fluid stream and subsequent absorption of the sulfur dioxide formed thereby in a two-stage countercurrent scrubber operating at conditions favorable for high bisulfite and low sulfite formation and selective away from carbon dioxide absorption.

Abstract: Hydrogen sulfide can be removed selectively from a gas stream also containing carbon dioxide at high pressure, such as those found at natural gas production wellheads, by contacting the gas stream with an alkaline liquid for a time period of less than about 80 milliseconds.

Abstract: A method of removing hydrogen sulfide from a sour gaseous stream in a contact zone by contacting the sour gaseous stream with a H.sub.2 S selective absorbent in an aqueous alkaline solution containing a polyvalent metal chelate at a pH of about 7 to about 10 wherein the polyvalent metal chelate is in one embodiment of the invention 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 absorbed hydrogen sulfide, hydrosulfide and/or sulfide salts present in the contact zone to sulfur. In a second embodiment, the aqueous alkaline solution and H.sub.2 S selective absorbent in contact with the gaseous stream is a mixture containing a higher valence polyvalent metal chelate together with a lower valence polyvalent metal chelate.