Abstract: The present invention describes an extractive oxidation process for removing contaminants from hydrocarbon streams using an ionic liquid combined with an organometallic ionic complex of iron(II), which comprises a complex of iron(II) cation with an ionophilic binder, catalyst of iron(II) with ionophilic binder in its molecular structure, oxidation of which is performed with an oxidizing agent and is catalysed by the organometallic iron(II) complex present in the phase of the ionic liquid. Besides maintaining its characteristics of selective solvent of oxidizing compounds, the ionic liquid combined with the organometallic complex of iron(II) with catalytic ionophilic binder of the oxidizing agent, stimulating the reactive phenomenon taking place in the ionic liquid phase, with the effect that the iron remains stable in the ionic liquid phase, without being leached into the oily phase. This measure results in a considerable improvement in removal of the heteroatoms from the hydrocarbon medium.

Abstract: The present invention discloses a method for aluminum-enhanced dealkalization of red mud and separation and recovery of aluminum and iron. The method includes: dissolving red mud in water, introducing excessive SO2, introducing O2 for aeration, and refluxing part of alkaline leachate after filtering; when pH of a red mud mixture decreases to below 3, washing and filtering the red mud mixture, adding NaOH to acidic leachate to adjust its pH to a strongly alkaline level, aging and filtering the leachate, treating filter residue to recover Fe2O3, and refluxing part of alkaline leachate after filtering to the red mud mixture; and adjusting pH of the remaining alkaline leachate after filtering to a weakly acidic level, and conducting filtering to recover aluminum.

Abstract: A process and method for removing hydrogen sulfide from a gas and regenerating ferric ions consumed in the hydrogen sulfide scrubbing process at low pH. A two-scrubber regenerative chemical scrubbing system for removing hydrogen sulfide from a gas that provides an economical system for removing hydrogen sulfide from a gas at low pH without the need for chelating agents. An oxide of manganese is used as a catalyst to enhance the regeneration of ferric ions in an aqueous solution under acidic conditions in the presence of oxygen. The process may further include contacting the aqueous solution with a second gas comprising air to replenish the dissolved oxygen in the aqueous solution. The regenerated solution comprising ferric ions can be reused to treat additional hydrogen sulfide containing gases.

Abstract: Disclosed are a system and a method for desulfurization and denitrification of an alumina calcination flue gas, and a use. The system comprises an ozone generator, a red mud pre-impregnation slurry scrubbing tower, and a red mud pre-impregnation tank and a red mud pre-impregnation clear liquid scrubbing tower. NOx in a flue gas is oxidized into a high valence oxynitride by ozone, and with the red mud as an absorbent, the synergistic absorption of SO2 and NOx in the flue gas is achieved, while the dealkalization of the red mud is achieved. By means of the synergistic catalytic oxidation of metal ions such as Fe3+ in a red mud slurry and ozone, the synergistic absorption of sulfur and oxynitride is prompted; and the use of a structure of staged absorption in two towers overcomes the problem of the difficulty in absorbing NO2 with a low O3/NOx molar ratio.

Abstract: The present invention generally relates to a process for making a metal oxide composition for use in removing contaminants from streams. A process of the present disclosure comprises contacting a metal salt with an aqueous solvent to form a metal salt mixture and reacting the metal salt mixture and a metal powder without the addition of heat. The present invention also relates to a process for making a coated metal oxide substrate.

Abstract: Compositions that can be used to adsorb low concentration, of unwanted or target substances from a dynamic fluid stream or from an enclosed static vapor phase. Such adsorbency can be obtained with thermoplastic materials used in the form of bulk polymer or a film, fiber, web, woven fabric, non-woven fabric, sheet, packaging and other such structures including or surrounding the enclosed volume. The concentration should be reduced to non-offensive sensed limits or a limit that does not produce a biological response.

Abstract: Methods for preparing a composition containing amorphous iron oxide hydroxide. Methods for regeneration of the amorphous iron oxide hydroxide after it has been used as desulfurizer. Regenerable desulfurizer with high sulfur capacity containing amorphous iron oxide hydroxide, not less than 88% w/w, and organic binder not less than 7% w/w. The organic binder is sodium carboxymethylcellulose, sesbania powder, cellulose powder, or a mixture thereof A method for preparing the desulfurizer. A method for regenerating the waste agent produced after the desulfurizer and the composition containing the desulfurizer are used as desulfurizer. This method allows the desulfurizer and the composition containing the desulfurizer to be regenerated and reused avoiding the need for landfill disposal and environmental pollution.

Abstract: There are provided an oxygen scavenger composition and the like, which are excellent in economy in which the amount of oxygen absorbed per unit volume of the oxygen scavenger composition is large, and rusting at high humidity is inhibited. The oxygen scavenger composition of the present invention comprises (A) an iron powder, (B) a metal bromide and/or a metal iodide, and (C) a thiosulfate.

Abstract: The invention involves the formation of a stable iron (II) oxide and/or hydroxide. Preferably these oxides and/or hydroxides are present as nanoparticles in the 5-10 nanometer range. It has been discovered that such particles can be formed at lower cost and with fewer impurities by using ferrous carbonate (FeCO3) from siderite as compared to known processes from various iron salts such as sulfates and chlorides. The novel nanoparticles are particularly adapted to removing sulfur compounds such as H2S from liquid and/or gaseous streams, such as hydrocarbon streams.

Abstract: The present invention relates to a method for removing sulfur from a gaseous or liquid mixture. This method involves contacting the gaseous or liquid mixture with an iron-enriched matrix under conditions effective to remove sulfur from the mixture through adsorption of the sulfur to the matrix. The iron-enriched matrix used in this method is a lignocellulosic material that is enriched with iron. The present invention also relates to a system, composition, and plant fertilizer that contain the iron-enriched matrix. Methods of making the composition and preparing a plant fertilizer are also disclosed.

Abstract: Disclosed are a compound including an oxalate, a carbon dioxide absorbent including the same, a method of preparing the carbon dioxide absorbent and a method of removing carbon dioxide, which may overcome issues of high recycling energy and low absorptivity of a conventional carbon dioxide absorbent to considerably reduce recycling energy and absorb a greater amount of carbon dioxide per unit absorbent, so that a size of a carbon dioxide absorption tower may be reduced and a less amount of recycling energy may be used, contributing to a substantial decrease in device manufacture costs and management costs.

Abstract: The invention involves the formation of a stable iron (II) oxide and/or hydroxide. Preferably these oxides and/or hydroxides are present as nanoparticles in the 5-10 nanometer range. It has been discovered that such particles can be formed at lower cost and with fewer impurities by using ferrous carbonate (FeCO3) from siderite as compared to known processes from various iron salts such as sulfates and chlorides. The novel nanoparticles are particularly adapted to removing sulfur compounds such as H2S from liquid and/or gaseous streams, such as hydrocarbon streams.

Abstract: Dry processes, apparatus, compositions and systems are provided for reducing emissions of sulfur oxides, and sulfur dioxide in particular, and/or HCl in a process employing a combination of a dolomite hydrate sorbent and a sorbent doping agent administered to achieve coverage of a three-dimensional cross section of a passage carrying SOx and/or HCl —containing gases with a short but effective residence time at a temperature effective to provide significant sulfur dioxide and/or HCl reductions with high rates of reaction and sorbent utilization. The once-through, dry process can advantageously introduce the sorbent and sorbent doping agent dry or preferably as a slurry to enable uniform treatment. Preferred sorbent doping agents include water-soluble or water-dispersible copper and/or iron compositions which can be heated to an active form in situ by the flue gases being treated.

Abstract: The present invention discloses an adsorbent material having the following formula: CuwZnFeyAlz(OH)2(A)(y+z)/2.mH2O, wherein w+x+y+z=1; and 0.20?w?0.60; 0.20?x?0.60; 0.05?y?0.25; 0.05?z?0.25; 0.20?(y+z)?0.33; and 0.50?m?0.80; a process for producing the adsorbent material and its use for removing sulfur-containing matter from gaseous streams.

Abstract: Methods for preparing a composition containing amorphous iron oxide hydroxide. Methods for regeneration of the amorphous iron oxide hydroxide after it has been used as desulfurizer. Regenerable desulfurizer with high sulfur capacity containing amorphous iron oxide hydroxide, not less than 88% w/w, and organic binder not less than 7% w/w. The organic binder is sodium carboxymethylcellulose, sesbania powder, cellulose powder, or a mixture thereof A method for preparing the desulfurizer. A method for regenerating the waste agent produced after the desulfurizer and the composition containing the desulfurizer are used as desulfurizer. This method allows the desulfurizer and the composition containing the desulfurizer to be regenerated and reused avoiding the need for landfill disposal and environmental pollution.

Abstract: Hydrogen sulfide and mercaptans in hydrocarbons, gas mixtures of hydrocarbons and the like may be scavenged therefrom by being brought into intimate contact with a mercaptan scavenger formulation of quaternary ammonium alkoxide or hydroxide in the presence of a high oxidative state metal such as cobalt, iron, chromium and/or nickel. The high oxidative state metal, being an oxidizer, acts as a catalyst when combined with the quaternary ethoxide or hydroxide for improved mercaptan scavenging performance.

Abstract: The present invention generally relates to a process for making a metal oxide composition. The present invention also relates to a process for making a coated metal oxide substrate.

Abstract: The present invention relates to an improved desulfurization process using an ionic liquid compound of general formula C+A?, where C+ represents an organic cation such as alkyl-pyridinium, di-alkyl imidazolium and tri-alkyl imidazolium; and A? is an anion of halides of iron (III), such as, for example, FeCl4?. The desulfurization process is also improved when producing the ionic liquid compound by heating the reactants using microwave energy. The ionic liquids can be used to desulfurize hydrocarbon mixtures by a liquid-liquid extraction.

Abstract: A composite magnesium hydroxide containing a carbonate group and having a large BET specific surface area, a method for producing the same and an adsorbent comprising the same. The composite magnesium hydroxide is represented by the following formula (1) and has a BET specific surface area of 100 to 400 m2/g. Mg1-xMx(OH)2-y(CO3)0.5y.mH2O ??(1) (in the above formula, M is at least one divalent metal ion selected from the group consisting of Zn2+, Cu2+, Ni2+, Co2+, Ca2+, Mn2+, Fe2+, and Ba2+, and x, y and m satisfy the following conditions: 0<x?0.5 0.02?y?0.7 0?m?1.

Abstract: The present invention relates to an ionic liquid compound of general formula C+A?, where C+ represents an organic cation such as alkyl-pyridinium, di-alkyl imidazolium and tri-alkyl imidazolium; and A? is an anion of halides of iron (III), such as, for example, FeCl4? and to a method of producing the ionic liquid compound by heating the reactants using microwave energy. The ionic liquids can be used to desulfurize hydrocarbon mixtures by a liquid-liquid extraction.

Abstract: An adsorbent for desulfurizing cracking gasoline or diesel fuel comprising 1) pillared clay, (2) inorganic oxide binder, (3) an oxide of one or more metals selected from Groups IIB, VB and VIB, and (4) at least one metal accelerant selected from cobalt, nickel, iron and manganese. The adsorbent exhibits excellent abrasion-resistant strength and desulfurization performance.

Abstract: Absorbing oxygen from a closed space at a rapid rate, particularly in food packaging, is made possible by introducing an alcohol-water mixture as an activator for iron-based absorber systems, preferably including an acid to control pH. Preferred alcohols are aliphatic alcohols, particularly, monohydric alkanols, such as methanol, ethanol, n-propanol, isopropanol, sec-butanol and t-butanol. Such absorber-activator combinations are capable of rapidly reducing the oxygen in a closed package. A preferred acid is orthophosphoric acid used in an amount sufficient to establish a pH of about 0.6 to 4. A preferred iron-based absorber system employs sponge iron, optionally including a dibasic acid cooperating with the orthophosphoric acid to control pH in the system. In one preferred embodiment, the iron-based absorber is pre-activated by contacting with the activator in the substantial absence of oxygen for a predetermined period of time.

Abstract: The present invention relates to the use of metal oxide particles held on carrier particles and moistened with a hygroscopic moistening agent, preferably glycol, with the moistened metal oxide particles used in a system designed to remove sulfur from dehydrated and water under-saturated gas compounds.

Abstract: The use of base/clay composites materials as sorbents for the removal of SO.sub.2 and SO.sub.3 (SO.sub.x) from flue gas and other sulfur containing gas streams is described. The base is either an alkaline earth metal carbonate (eg. CaCO.sub.3) or hydroxide (eg. Ca(OH).sub.2) is incorporated onto the clay by precipitating from corresponding metal oxide (eg. CaO) in an aqueous clay slurry. A second metal oxide or oxide precursor, preferably selected from transition metal ions, capable of promoting the oxidation of sulfur dioxide to sulfur trioxide, is incorporated to the base/clay composite during the synthesis in the form of finely divided metal oxide powder, metal oxide sol, water soluble metal salt or as clay-intercalated metal cation. The use of clay as dispersing agent for both the basic oxide and the second metal oxide component decreases the particle agglomeration of base particles and increases the rate of SO.sub.x uptake compared to the bulk bases in current use.

Abstract: A stable, salt-free iron chelate for use in aqueous alkaline systems is prepared by contacting iron oxide with an aqueous mixture of from 30 to 45 mole percent trisodium HEDTA and from 55 to 70 mole percent EDTA, heating the mixture to dissolve the iron, and adjusting the pH to from 7 to 10 with base.

Abstract: An air purifying agent comprising a carrier which contains short pulp fiber, on which one or more chemical components selected from the group consisting of acids, alkalis, oxidizing agents, reducing agents and antimicrobial components are supported. According to the present invention, an air purifying agent which is low in weight, is safe to handle and exhibits excellent effect in removing contaminated gases containing low concentrations of contaminants.

Abstract: A process for producing a sulfur sorbent composition in a mixer having a mixer paddle an energy supply is disclosed which includes hydrating an alkaline earth metal oxide in an aqueous solution containing a promoting additive selected from a group consisting of urea and mixtures of urea with a water soluble iron salt under high intensity mixing conditions with the mixer wherein the mixer is operated at a mixer paddle tip velocity of at least 500 ft/min and a mixer energy input of at least 3.5 kW-h per ton of sorbent so as to produce a sulfur sorbent composition having the following physical and chemical properties: alkaline earth metal (wt. %)--40-52, molar ratio of promoting additive to alkaline earth metal--0.001-0.2, bulk density (g/ml)--0.35-0.75, surface area (m.sup.2 /g)--5-25, pore volume (cc/g)--0.05-0.14 and mean particle size (um)--4.

Abstract: The use of base/clay composites materials as sorbents for the removal of SO.sub.2 and SO.sub.3 (SO.sub.x) from flue gas and other sulfur containing gas streams is described. The base is either an alkaline earth metal carbonate (eg. CaCO.sub.3) or hydroxide (eg. Ca(OH).sub.2) is incorporated onto the clay by precipitating from corresponding metal oxide (eg. CaO) in an aqueous clay slurry. A second metal oxide or oxide precursor, preferably selected from transition metal ions, capable of promoting the oxidation of sulfur dioxide to sulfur trioxide, is incorporated to the base/clay composite during the synthesis in the form of finely divided metal oxide powder, metal oxide sol, water soluble metal salt or as clay-intercalated metal cation. The use of clay as dispersing agent for both the basic oxide and the second metal oxide component decreases the particle agglomeration of base particles and increases the rate of SO.sub.x uptake compared to the bulk bases in current use.

Abstract: The present invention relates to an improved sorbent for use in removing effluents such as sulfur dioxide from combustion gas streams. The sorbent comprises a hydroxide formed from an alkaline-earth based material such as lime and having incorporated therein an iron and organic compound promotion addition to enhance its ability to remove effluents from the gas stream. The sorbent is formed by co-dissolving an iron salt and an organic compound in a hydration solution and thereafter mixing the hydration solution containing the iron salt and the organic compound with an alkaline-earth based material. The sorbent thus produced may be injected into a gas stream in either dry or slurry form to remove the effluents.

Abstract: A process for producing a sulfur sorbent composition in a mixer having a mixer paddle an energy supply is disclosed which includes hydrating an alkaline earth metal oxide in an aqueous solution containing a promoting additive selected from a group consisting of urea and mixtures of urea with a water soluble iron salt under high intensity mixing conditions with the mixer wherein the mixer is operated at a mixer paddle tip velocity of at least 500 ft/min and a mixer energy input of at least 3.5 kW-h per ton of sorbent so as to produce a sulfur sorbent composition having the following physical and chemical properties: alkaline earth metal (wt.%)--40-52, molar ratio of promoting additive to alkaline earth metal--0.001-0.2, bulk density (g/ml)--0.35-0.75, surface area (m.sup.2 /g)--5-25, pore volume (cc/g)--0.05-0.14 and mean particle size (.mu.m)--4.

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: 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 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 is provided for the froth flotation of oxide and salt type minerals utilizing as the collector a combination of a monoester of a dicarboxylic acid of the general formula ##STR1## in which R' is an aliphatic hydrocarbon group with 7-21 carbon atoms, R" is a hydrocarbon radical with 2-6 carbon atoms and A is an alkylene oxide group derived from an alkylene oxide with 2-4 carbon atoms; and a monocarboxylic acid having the general formulaR'"COOH IIwherein R'" is a hydrocarbon group with 5-23 carbon atoms, the acid as being in an amount to increase the yield and/or the selectivity of the monoester in the flotation of alkaline earth metal-containing oxide and salt type minerals, such as apatite, fluorspar, calcite, baryte, scheelite, dolomite, and magnesite.

Abstract: A method for cleaning a surface of a substrate which comprises treating the surface with a dichloro-pentafluoro-propane solvent. The method is specifically directed to the use of 1,1-dichloro-2,2,3,3,3-pentafluoro propane and 1,3-dichloro-1,1,2,2,3-pentafluoropropane as the cleaning solvent.

Abstract: H.sub.2 S abatement in geothermal drilling operations (e.g. drilling, flow testing and reworking) with a ferric aminocarboxylic acid chelating solution containing a stabilizer and an optional cationic polyelectrolyte catalyst which is injected in the blooie line of the well upstream of the separator. The stabilizer is a hydroxyl radical scavenger such as iodide, nitrite, amino acid, aliphatic aldehyde, sugar, ascorbate, formate and/or aryl sulfonic acid, and inhibits degradation the ferric aminocarboxylic acid complex.

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: The present invention relates to a new alkaline absorbent solution that reduces the H.sub.2 S content in a treated gas to below 10 vppm. The absorbent solution contains two severely-hindered amines, such as bis(tertiarybutylaminoethoxy)-ethane (BTEE) and ethoxyethoxyethanol-tertiarybutylamine (EEETB), a severely hindered amine salt, and/or a severely hindered aminoacid. This invention also describes a process for the removal of H.sub.2 S from fluid mixtures using this absorbent solution to produce a very low level of H.sub.2 S in the treated fluid. The process is also suitable for the selective removal of H.sub.2 S from fluid mixtures comprising H.sub.2 S and CO.sub.2.

Abstract: A new alkaline absorbent solution containing a severely-hindered amine and a severely-hindered aminoacid is provided. A process for the removal of H.sub.2 S from fluid mixtures using this absorbent solution to produce a very low level of H.sub.2 S in the treated fluid is also provided. The process is also suitable for the selective removal of H.sub.2 S from fluid mixtures comprising H.sub.2 S and CO.sub.2. Use of the above absorbent solution leads to higher selectivity for H.sub.2 S than observed when the severely-hindered amine is used alone without the severely-hindered aminoacid.

Abstract: The present invention relates to a mixture of severely-hindered amines, such as bis-(tertiarybutylaminoethoxy)-ethane (BTEE) and ethoxyethoxyethanoltertiarybutylamine (EEETB), and a one-step synthesis method for its preparation. Besides, this invention describes the use of the mixture for the removal of H.sub.2 S, especially the selective removal of H.sub.2 S in the presence of CO.sub.2.

Abstract: A new alkaline absorbent solution containing a tertiary amino azabicyclic alcohol in combination with its salt with a strong acid and/or in combination with a severely-hindered aminoacid is provided. A process for the removal of H.sub.2 S from fluid mixtures using this absorbent solution to produce a very low level of H.sub.2 S in the treated fluid is also provided. The process is also suitable for the selective removal of H.sub.2 S from fluid mixtures comprising H.sub.2 S and CO.sub.2. Use of the above absorbent solution leads to higher selectivity for H.sub.2 S without damaging capacity than observed when the tertiary amino azabicyclic alcohol is used alone without additive.

Abstract: A new alkaline absorbent solution containing the additive of a severely-hindered amine salt and/or a severely-hindered aminoacid to a non-hindered amine such as N-methyldiethanolamine (MDEA) is provided. A process for the removal of H.sub.2 S from fluid mixtures using this absorbent solution to produce a very low level of H.sub.2 S in the treated fluid is also provided. The process is also suitable for the selective removal of H.sub.2 S from fluid mixtures comprising H.sub.2 S and CO.sub.2. Use of the above absorbent solution leads to higher selectivity for H.sub.2 S than observed when MDEA is used alone without the additives.

Abstract: A method of removing hydrogen sulfide and carbon dioxide from a sour gaseous stream in a contact zone by contacting the sour gaseous stream with a lean CO.sub.2 -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 reduce 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 and CO.sub.2 -selective absorbent contact in the gaseous stream is a mixture containing a minor amount of higher valence polyvalent metal chelate together with a major amount of a lower valence polyvalent metal chelate.

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: Process for removing H.sub.2 S from the exhaust steam in a geothermal power plant wherein the H.sub.2 S containing steam is contacted with an aqueous solution containing a ferric chelate and a cationic polymeric catalyst such as poly dimethyl diallyl ammonium chloride. The conversion of H.sub.2 S to sulfur is accelerated by the use of a small amount of the catalyst.

Abstract: A process for removing SO.sub.x pollutants from a stack gas by (1) absorbing the SO.sub.x pollutants into an aqueous absorbent containing a formate compound and (2) regenerating the spent absorbent containing dissolved SO.sub.x compounds by contact, in the presence of added formate anion, with a water-insoluble, solid substance containing one or more tertiary amine functional groups. Nitrogen monoxide is removed by providing in the aqueous absorbent an iron(II) chelate, such as a chelate of ferrous ion with ethylenediaminetetraacetic acid. Regeneration of the spent absorbent containing absorbed NO is accomplished under the same conditions as for spent absorbents containing absorbed SO.sub.x compounds. SO.sub.x and NO pollutants dissolved in the absorbent are, during regeneration, converted to hydrogen sulfide and nitrogen, respectively.

Abstract: Methods are disclosed for the purification of mixed gas streams containing hydrogen sulfide, carbon dioxide, carbon monoxide, sulfur, hydrogen, and methane and other hydrocarbon gases, and mixtures thereof, by the use of an oxidizing reactive solid. In one method, the oxidizing reactive solid is, in a first step, contacted with the mixed gas stream which may contain, among other gases, hydrogen sulfide and carbon dioxide. The reactive solid removes the hydrogen sulfide in the form of elemental sulfur with no detectable formation of sulfur oxide. The reactive solid also partially removes the carbon dioxide from the mixed gas stream. In the second step of the first method, the oxidizing reactive solid is regenerated by flowing air. In a second method of the present invention, mixed gas streams, containing hydrogen sulfide and oxygen in an approximate stoichiometric amount, are contacted with the solid, and hydrogen sulfide is converted directly to sulfur with minimal formation of compounds of sulfur.

Abstract: A method, applicable to hydrogen sulfide removal systems which employ a regenerable aqueous washing solution capable of absorbing hydrogen sulfide and converting that hydrogen sulfide to elemental sulfur, is provided for reconditioning such systems after they have become contaminated with sulfur-feeding bacteria and/or for maintaining such systems substantially free of such bacteria. In the method of the invention, the aqueous washing solution is contacted with an aliphatic dialdehyde.

Abstract: A composition is provided which comprises an aqueous alkaline solution of a metal salt and black liquor, the metal salt being selected from the group consisting of iron, chromium, cobalt and nickel salts. This composition is useful in a process described for absorption of hydrogen sulfide from flue gas, followed by subsequent oxidation of dissolved sulfide to thiosulfate, if desired. The presence of the metal ions and black liquor synergistically catalyzes the overall reaction of absorption of hydrogen sulfide, followed by oxidation of the sulfide. Preferably, prior to scrubbing to remove hydrogen sulfide with the solution, the flue gas is first cooled to near its dew point, and then scrubbed with water to remove particulates. Additionally, the effluent flue gas from the absorption step is usefully scrubbed with water to recover heat, following which it is used to scrub condensates from a kraft pulp mill. The metal salt in the solution is preferably an iron salt at a concentration of about 0.002 M.

Abstract: A process to remove SO.sub.2 from mixtures by contacting SO.sub.2 -containing mixtures with a regenerable iron-bearing sorbent such as paint rock under reaction conditions to produce iron sulfide and an effluent containing reduced amounts of SO.sub.2.