Abstract: The present disclosure relates to processes for desulfurizing hydrocarbon feedstocks. The processes may include introducing a feedstock comprising hydrogen sulfide to an absorber comprising a metal chelate to form a reduced metal chelate. The processes may further include introducing the reduced metal chelate to a photobioreactor comprising a phototrophic bacterium. The present disclosure also relates to apparatuses for desulfurizing hydrocarbon feedstock. An apparatus may include and absorber and a photobioreactor fluidly connected to the absorber. The photobioreactor may be an anaerobic vessel with a light source.

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: 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: A system for hydrogen sulfide removal from a sour gas mixture including hydrogen sulfide. The sour gas mixture is reacted with a transition metal compound in a scrubber. Sulfide from the hydrogen sulfide is oxidized to form elemental sulfur and the transition metal is reduced to form a reduced state transition metal compound. An electrochemical redox reaction is performed including the reduced state transition metal compound to regenerate the transition metal compound in an electrolyzer including a power source. During the electrochemical redox reaction a voltage from the power source applied to the electrolyzer is controlled to regenerate the transition metal compound at a rate sufficient to match a flow rate of hydrogen sulfide into the scrubber or maintain a predetermined maximum hydrogen sulfide level out from the scrubber. The transition metal compound regenerated is returned to the scrubber for the reacting.

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: 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: The invention relates to a process for removing sulfur particles from an aqueous catalyst solution used to remove hydrogen sulfide from a gas stream (1, 5), comprising the steps of directing a flow of a suspension (12) comprising reduced catalyst solution and sulfur particles to an oxidizer zone (20), where the catalyst solution is regenerated by contacting said suspension with a gas (22) containing oxygen; and removing sulfur from said suspension at least by gravity sedimentation at a bottom (21) of said oxidizer zone (20). According to the invention a flow deflecting means (34) is disposed at least at an outlet (35) for the oxidized catalyst solution leaving said oxidizer zone (20) such as to prevent any turbulent state caused at least by a stream of oxidized catalyst solution leaving said oxidizer zone (20).

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: A high activity catalyst is obtained by oxidizing and modifying the surface of zinc sulfide by hydrogen peroxide. An oxidation treatment is carried out in basic aqueous solution. The high activity photocatalyst is added to the basic aqueous solution in which hydrogen sulfide is dissolved to recover hydrogen and sulfur under low energy. Thus, the inexpensive high activity photocatalyst having a high catalytic activity and a long duration of life is realized and hydrogen gas is efficiently generated under little energy.

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: 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: 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: 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.