Abstract: A method for removing sulfides from an aqueous liquid, wherein the aqueous liquid is contacted with an oxidizer in the presence of fibrous material dyed with at least one sulfur dye or sulfurized vat dye, to convert the sulfides in the aqueous liquid to a non-toxic product.

Abstract: A method for removing hydrogen sulfide from a biogas, wherein the hydrogen sulfide is absorbed in an aqueous liquid to produce a cleaned gas having a reduced amount of hydrogen sulfide relative to the biogas. The aqueous liquid is subsequently treated by contacting with a sulfur dye or sulfurized vat dye in the presence of an oxidizer such as oxygen gas, to convert the sulfides in the aqueous liquid to a non-toxic, water-soluble, product.

Abstract: A method for treating sulfide in an aqueous fluid comprises contacting the fluid with an oxidizer in the presence of a sulfur dye or sulfurized vat dye. In one embodiment, the method comprises treating sulfide contaminated water by contacting the contaminated water with air in the presence of a sulfur dye or a sulfurized vat dye. The method is useful for remediating industrial, agricultural, and municipal waste water.

Abstract: A method used in connection with the recovery of pulping chemicals from spent pulping liquor produced by kraft-type pulping at very high sulphidity. In the method, spent pulping liquor is acidified to a relatively low pH which converts a most or all of the sulphide and hydrosulphide in the liquor to hydrogen sulfide. Sulphur containing gases released from the acidification of the spent pulping liquor, together with other sulphur gases collected at the pulp mill, are converted into an acid compound. This acid compound is employed as an acidification agent in the acidification of the spent pulping liquor. The amount of acid compound generated by the conversion of sulphur containing gases may be sufficient to provide most, if not all, of the acid needed for the acidification of the spent pulping liquor.

Abstract: A process for recovering sulfur from a hydrogen sulfide-bearing gas utilizes an aqueous reaction medium, a temperature of about 110-150° C., and a high enough pressure to maintain the aqueous reaction medium in a liquid state. The process reduces material and equipment costs and addresses the environmental disadvantages associated with known processes that rely on high boiling point organic solvents.

Abstract: The present invention relates to a process for the catalytic oxidation of sulphide, mono- and/or dihydrogen sulphide, comprising the step of contacting the sulphide, mono- and/or dihydrogen sulphide in the presence of oxygen with a chelate complex comprising (i) a metal cation selected from the group consisting of Fez+, Mnz+, Niz+ and Coz+, where z=2 or 3, and (ii) a chelate ligand containing a porphyrin, a phthalocyanine or a porphyrazine ring coordinated to the metal cation, and at least one cationic substituent covalently attached to the ring in the chelate ligand.

Abstract: The present invention provides a method of treating an off-gas stream (80) comprising NH3 and H2S to provide a sulphate stream (910), the method comprising the steps of: (i) providing a first off-gas stream (80) comprising NH3, H2S, CO2 and optionally one or more of HCN, COS and CS2; (ii) passing the first off-gas stream (80) to an incinerator (300) to oxidize NH3, H2S, and optionally one or more of HCN, COS and CS2 to provide a second off-gas stream (310) comprising N2, H2O, SO2 and CO2; (iii) scrubbing the second off-gas stream (310) with a first aqueous alkaline stream (380, 876a) in a caustic scrubber (350) to separate SO2 and a part of the CO2 from the second off-gas stream to provide a spent caustic stream (360) comprising carbonate and one or both of sulphite and bisulphite and a caustic scrubber off-gas stream (370) comprising N2 and CO2; and (iv) passing the spent caustic stream (360) to an aerator (900) comprising sulphur-oxidizing bacteria in the presence of oxygen to biologically oxidize sulphite

Abstract: An improved process for reduction-oxidation desulphurization uses an oxidizer operating at a pressure greater than the absorber where a liquid reduction-oxidation catalyst solution contacts a sulfur-containing gas feed stream.

Abstract: Gas sweetening solutions are described that are capable of removing hydrogen sulfide from gas streams. These gas sweetening solutions increase the size of produced sulfur particles and thereby improve efficiency of their separation, while simultaneously reducing corrosive effects of the sweetening solutions. The gas sweetening solutions comprise at least one chelating agent, cationic iron and a mixture of nitrite salt and phosphate species.

Abstract: A system may include a sulfur recovery unit. The sulfur recovery unit may include an acid gas supply, which may supply acid gas, an oxygen supply, which may supply oxygen, a fuel supply, which may supply fuel. The fuel may have a higher heating value than the acid gas. Also, the sulfur recovery unit may include a thermal reaction zone, which may thermally recover sulfur from the acid gas by combustion of the fuel and the acid gas with the oxygen and through reaction of the acid gas with combustion products arising from the combustion.

Abstract: A method for removing hydrogen sulfide from a sour gas stream comprising hydrogen sulfide by oxidizing hydrogen sulfide in a converter by contacting the sour gas stream with an aqueous catalytic solution, thereby producing a desulfurized gas stream and a liquid stream comprising reduced catalyst and elemental sulfur, introducing an oxidant and the liquid stream comprising reduced catalyst and elemental sulfur into a high shear device and producing a dispersion wherein the mean bubble diameter of the oxidant gas in the dispersion is less than about 5 ?m, introducing the dispersion into a vessel from which a sulfur-containing slurry is removed and a regenerated catalyst stream is removed, wherein the sulfur slurry comprises elemental sulfur and aqueous liquid, and recycling at least a portion of the regenerated catalyst stream to the converter. A system of apparatus for carrying out the method is also provided.

Abstract: A method operable to remove contaminants from a contaminated fluid stream is provided. The process includes receiving the fluid stream containing contaminants. A first portion of the contaminants are removed from the fluid stream with a first scrubbing vessel. A first base solution reacts with the contaminants such that the contaminants enter a contaminant solution. A remaining portion of the contaminants from the fluid stream is then removed with a at least one additional scrubbing vessel, wherein a second base solution reacts with the contaminants such that part of the remaining portion of the contaminants enter a second solution. Water content is then removed from the fluid stream with a desiccating module, wherein the desiccating module outputs a clean fluid stream.

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.

Abstract: Hydrogen sulfide is oxidized to sulfur by means of treatment with an aqueous acid solution containing trivalent iron and a hetero polyacid having formula (I): HnXVyM(12-y)O40; or a sole hetero polyacid having formula (II): HnMeM12O40; wherein the symbols X, M Me n and y are specified in the text. At the end of the oxidation, the solution is treated with gas containing oxygen to re-oxidize the reduced metal.

Abstract: Process for the production of sulfur, obtained in pure form, and possibly easily disposable even at ambient temperature, starting from hydrogen sulphide contained in natural gas, which includes: a) oxidizing a portion of hydrogen sulphide to sulfur dioxide; b) dissolving in water the sulfur dioxide obtained in step (a); c) carrying out the reaction (I): 2H2S+SO2?3S+2H2O (I) making the remaining hydrogen sulphide to react with the solution prepared in step (b); and d) using the thus obtained sulfur suspension for the production sulfur or, alternatively, to use it for the disposal of the sulfur itself in a site reserved for such purpose.

Abstract: The present application relates to a process for removing hydrogen sulfide H2S from a gas (1) by contacting said gas with a liquid solution (2) containing ferric sulfate in an absorption column (RC). Ferric sulfate and H2S react at room temperature and at a pressure ranging from 1 to 1.2 atm. Ferric ions being reduced to two-valent iron and sulfide oxidised to elemental sulfur. The liquid (4) coming out of the absorption column is filtered in two steps, the retentate (6, 8) comprising elemental sulfur, the filtrate (5, 7) containing the iron ions. The filtrate is sent to a bioreactor (RB) for regeneration, i.e. oxidation of iron to Fe3+ by means of thiobacillus ferroxidans and air injection (10). The regenerated solution is reused in the absorption column (RC). The process faces the problems relating to the alignment between the chemical step and the biological step in order to obtain a process which can stably run continuously.

Abstract: The invention relates to a process for removing hydrogen sulfide and recovering sulfur from a gas stream, comprising the steps of: contacting said gas stream with an aqueous catalyst solution of a polyvalent metal redox catalyst in a contacting zone to absorb said hydrogen sulfide and form a reduced catalyst solution comprising reduced polyvalent metal redox catalyst and sulfur particles; oxidizing said reduced catalyst solution while removing sulfur particles to form said oxidized aqueous catalyst solution comprising polyvalent metal redox catalyst in an oxidized state with sulfur particles removed; and recovering sulfur by transferring at least one of said sulfur particles and foam to a separation zone; wherein a coagulating reagent is added to a feed of said separation zone prior to entering said separation zone to promote settlement of sulfur particles.

Abstract: Contact of a crude feed with one or more catalysts produces a total product that includes a crude product. The crude feed has a residue content of at least 0.2 grams of residue per gram of crude feed. Methods of preparing the one or more catalysts are described. The crude product is a liquid mixture at 25° C. and 0.101 MPa. One or more properties of the crude product may be changed by at least 10% relative to the respective properties of the crude feed. The crude product may include hydrocarbons with different boiling point distributions.

Abstract: A method for removing H2S from H2S-containing gaseous streams in which an H2S-containing gaseous stream is introduced into a flow channel and at least one liquid chemical H2S scavenging agent is also introduced into the flow channel. Directly within the flow channel, liquid chemical H2S scavenging agent is transformed into a plurality of H2S scavenging agent droplets, which plurality of H2S scavenging agent droplets are contacted with the H2S-containing gaseous stream, whereby at least a portion of the H2S is absorbed by the plurality of H2S scavenging agent droplets. In accordance with one embodiment, transformation of the liquid chemical H2S scavenging agent is carried out in an inclined flow channel and in accordance with another embodiment, the transformation is carried out using ultrasonic atomization.

Abstract: An improved oxidizer for liquid reduction-oxidation desulphurization processes uses a hollow fiber membrane contactor. A pressurized, oxygen containing gas stream is introduced into the interior of the hollow fiber membrane while a liquid reduction-oxidation catalyst solution contacts the exterior of the membrane. Oxygen diffuses through the membrane into the liquid reduction-oxidation catalyst solution whereby the solution is oxidized and can be recycled for further use in a desulphurization process.

Abstract: An improved oxidizer for liquid reduction-oxidation desulphurization processes uses a hollow fiber membrane contactor. A pressurized, oxygen containing gas stream is introduced into the interior of the hollow fiber membrane while a liquid reduction-oxidation catalyst solution contacts the exterior of the membrane. Oxygen diffuses through the membrane into the liquid reduction-oxidation catalyst solution whereby the solution is oxidized and can be recycled for further us in a desulphurization process.

Abstract: The present invention relates to a process for regenerating an at least partly reduced catalytic redox solution. The solution includes at least one polyvalent metal chelated by a chelating agent and is circulated in at least one regeneration zone while an oxygen-containing gas is injected into the regeneration zone. The process includes measuring a concentration of oxygen dissolved in a regeneration zone effluent. The process also includes adjusting a flow rate of the at least partly reduce catalytic redox solution entering the at least one regeneration zone and/or an oxygen-containing gas entering the regeneration zone in response to a measured concentration of oxygen, until a concentration of oxygen in the regeneration zone effluent is less than 20% of an amount of oxygen dissolved in water saturated with oxygen. Thus, degradation of the chelating agent in the catalytic redox solution is minimized.

Abstract: A desulphurizing composition for the treatment of CLAUS plant tail gases, comprises: an organic solvent A with a boiling point of more than 200° C. at atmospheric pressure; a catalyst composition B of at least one alkali- or alkaline-earth salt (S) of an organic monoacid or an organic polyacid which has at least one dissociation constant value (pK) in the range 2.2 to 8 such as formic acid, acetic acid, ascorbic acid, fumaric acid, maleic acid, malonic acid, oxalic acid, tartaric acid, benzoic acid, salicyclic acid, and sulphosalicyclic acid; at least one complexing agent (C) such as an alkali or alkaline-earth salt or a ferrous or ferric salt of a mono- or poly-aminocarboxylic acid, citric acid, a sulphocyanide ion, a ferrocyanide ion, a ferricyanide ion, a phosphate ion, a pyrophosphate ion, a fluoride ion and/or a thiosulphate ion; and water (W), in the following proportions by weight: S=0.1% to 30%; C=0.001% to 30%; W=balance.

Abstract: In the desulfurization of a gaseous feed containing hydrogen sulfide, comprising contacting the gaseous feed with a catalytic solution containing a chelated polyvalent metal under suitable conditions for oxidation of the hydrogen sulfide to elementary sulfur and concomitant reduction of the chelated polyvalent metal from a higher oxidation level to a lower oxidation level, recovering a gaseous effluent substantially freed from hydrogen sulfide, and a catalytic solution at least partly reduced and containing elementary sulfur, separating the solid elementary sulfur from the reduced catalytic solution, and regenerating the reduced catalytic solution by contacting the catalytic solution with a gas containing oxygen by means of an ejector.

Abstract: A process intended for desulfurization of a gaseous feed containing hydrogen sulfide, includes at least the following stages: a) contacting the gaseous feed with a catalytic solution containing at least one polyvalent metal chelated by at least one chelating agent, under suitable conditions for oxidation of the hydrogen sulfide to elemental sulfur and concomitant reduction of the polyvalent metal from a higher oxidation level to a lower oxidation level, b) recovering on the one hand a gaseous effluent substantially freed from hydrogen sulfide and, on the other hand, the catalytic solution at least reduced and containing elemental sulfur, and c) recycling at least a fraction F1 of the catalytic solution at least reduced and containing solid elemental sulfur to absorption stage a) so as to reduce the number of sulfur grains of very small size.

Abstract: Disclosed is a method in which hydrogen sulfide-containing liquid sulfur is introduced into a containment vessel to partially fill the containment vessel and create a hydrogen sulfide-containing liquid sulfur phase and a hydrogen sulfide-containing vapor phase. A portion of the hydrogen sulfide-containing liquid sulfur phase is then treated to produce a liquid sulfur-containing phase and a gaseous hydrogen sulfide-containing phase, such that the gaseous hydrogen sulfide-containing phase has a pressure of at least about 60 psig. A portion of the hydrogen sulfide-containing vapor phase is then withdrawn from the containment vessel using at least one eductor driven by a motive fluid, where the motive fluid is the gaseous hydrogen sulfide-containing phase from the container vessel. The hydrogen sulfide-containing waste gas stream exiting the eductor is then treated to reduce the hydrogen-sulfide content of the waste gas.

Abstract: A method is provided for increasing the lifetime of Stretford solution by reducing or eliminating the generation of undesirable thiosulfate salts. The method has three major aspects. First, thiocyanate is added to the Stretford solution. Second, the concentration of sodium sulfate in the solution is maintained at a level below about 100 g/l. Third, the solution should contain little or no thiosulfate at the start of operations. It has been found that little or no thiosulfate is generated when the Stretford unit is operated under these conditions. The concentration of sodium sulfate in the solution is maintained at a level below about 100 g/l by removing sodium sulfate from the solution by cooling a slipstream of the solution to precipitate the sodium sulfate as Glauber's salt.

Abstract: High quality hydrophilic sulfur is recovered from a biologial conversion zone in which a sulfur containing compound such as a sulfide is converted to elemental sulfur. The sulfur is rendered hydrophilic due to the fine particle size and attachment of biomass to the particles. The sulfur is recovered as an undamaged agglomerate powder after being processed in at least two stages of purification.

Abstract: The invention relates to improvements in a known process and system wherein hydrogen sulfide is removed from a gaseous stream, using a nonaqueous scrubbing liquor in which are dissolved sulfur and a reaction-promoting amine base. In a first aspect of the invention sulfur dioxide is added to the sulfur-amine nonaqueous sorbent (or advantage is taken of SO2 which may already be present in the gas stream) to obtain better H2S removal, lower chemical degradation rates, and lower rates of formation of byproduct sulfur salts. In a further aspect of the invention the gas to be treated is mixed with oxygen and passed through an oxidation catalyst reactor to either effect oxidation of part of the H2S to form the required amount SO2 for reaction with the remaining H2S, or to effect partial oxidation of the H2S in the feed gas to form elemental sulfur, or to form various combinations of products as desired for the application, prior to scrubbing with the nonaqueous solvent.

Abstract: Process for the removal of carbon dioxide (CO2) and minor sulfur compounds—mainly hydrogen sulfide (H2S)—from a sour gas mixture, such as natural gas, iron ore reduction gas, etc. The process uses a continuous absorption process with an alkaline aqueous liquid mixture containing 15-40% by weight of equivalent K2CO3 and is conducted at a temperature of about 150 degrees F. to 300 degrees F. The H2S is removed from the sour gas as elemental sulfur. A high concentration (at least 10 to 1 molar ratio) of penta-valent vanadium (V+5) to H2S is maintained at a high temperature (150 to 300 degrees F.) to help minimize thiosulfate formation, raise the absorption temperature, and increase the speed of conversion of H2S to elemental sulfur. CO2 is stripped from the aqueous alkaline solution and vented directly into the atmosphere since the sulfur that usually contaminates the CO2 was removed earlier in the process as elemental sulfur.

Abstract: The invention disclosed relates to a process for removing hydrogen sulfide from a gas stream, such as sour natural gas, with the formation of elemental sulfur as a by-product. By controlling the reaction conditions, the conversion of hydrogen sulfide is maximized, and the sulfur dioxide selectivity is controlled. Specifically, the sulfuric acid concentration and the reaction temperature may be balanced, depending on the desired product mix.

Abstract: The invention is a process for separating acid gases from synthesis gas and treating the resulting solids. A mixture comprising synthesis gas and acid gas is contacted with a fluid that reacts with said acid gas to form a particulate solid dispersed in a fluid. The slurry comprising fluid and particulate solid is filtered to separate the particulate solid from the fluid by means of a regenerable filter. The particulate solids are removed from the regenerable filter by back-washing with a back-washing fluid to form a pumpable slurry comprising a mixture of particulate solids and back-washing fluid. The slurry is gasified to form synthesis gas and vitrified solids.