Abstract: Processes for the thermal reduction of sulfur dioxide to elemental sulfur are disclosed. The processes described include three general reaction sections, including the reaction furnace portion where the SO2-containing stream is combusted, the second reaction zone where the temperature is moderated to encourage the reaction of sulfur with hydrogen to consume the hydrogen carbon monoxide and produce the H2S and CO. The temperature moderation is achieved by one or combinations of three different methods adding external waste heat boiler, followed by a vessel to provide adequate residence time for the reaction of producing H2S or to recycle the tail gas to a second zone of a 2-zone reaction furnace, using inter-stage internal cooling coil or adding a quench fluid in the second zone of a 2-zone reaction furnace. The third reaction zone is a Claus conversion portion, wherein residual H2S and SO2 are further reacted to produce additional elemental sulfur.

Abstract: Processes for the thermal reduction of sulfur dioxide to elemental sulfur are described and disclosed. The processes described include three general reaction sections, including the reaction furnace portion where the SO2-containing stream is combusted, the second reaction zone where the temperature is moderated to encourage the reaction of sulfur with hydrogen to consume the hydrogen carbon monoxide and produce the H2S and CO with allowing adequate residence time. The temperature moderation is achieved by one or combinations of three different methods adding external waste heat boiler, followed by carbon steel refractory vessel to provide adequate residence time for the reaction of producing H2S or to recycle the tail gas to a second zone of a 2-zone reaction furnace, using inter-stage internal cooling coil or adding a quench fluid in the second zone of a 2-zone reaction furnace.

Abstract: Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

Abstract: A process for obtaining energy values contained in a sulphur-containing carbonaceous fuel, the process comprising (a) treating a feed carbonaceous fuel having a first bound-sulphur content with an effective amount of an oxygen and SO2-containing gas in a reactor at an effective temperature to (i) provide elemental sulphur from the SO2, (ii) release exothermic heat, and (iii) produce a hot effluent gaseous steam containing the elemental sulphur and treated fuel having a second bound-sulphur content, (b) separating the elemental sulphur from the treated fuel; (c) collecting the elemental sulphur; (d) collecting the treated fuel; and (e) collecting the exothermic heat.

Abstract: Apparatus and process for recovering elemental sulfur from a H2S-containing waste gas stream are disclosed. The apparatus preferably comprises a first reaction zone for carrying out the catalytic partial oxidation of H2S, a second reaction zone for the catalytic partial reduction of any incidental SO2 produced in the first reaction zone, and a cooling zone including a sulfur condenser. According to a preferred embodiment of the process, a mixture of H2S and O2 contacts a catalyst in the first reaction zone very briefly (i.e, less than about 200 milliseconds) producing primarily S0 and H2O. Some SO2 is also present in the first stage product gas mixture. A reductant gas (e.g. CO, or CH4 or natural gas) is fed together with the first stage product gas mixture to a second catalytic reaction zone where the partial reduction of the SO2 component to elemental sulfur and CO2 is carried out.

Abstract: A petroleum coke-based combined De-SOx and De-NOx process is described comprising use of four key units, namely, a flue gas concentrator (FC), a carbothermal reducer (CR), an elemental sulphur condenser (SC) and an oxidizer for reduced sulphur and nitrogen species (RO). The two major reactants in this process are the petroleum coke, preferably, and a flue gas containing SOx/NOx. The major products are elemental sulphur from the SC and activated coke from the CR. The process provides for SOx and NOx abatement in an economically viable way while the activated coke produced has a wide range of applications, particularly, in environmental protection.

Abstract: A process for obtaining energy values contained in a sulphur-containing carbonaceous fuel, the process comprising (a) treating a feed carbonaceous fuel having a first bound-sulphur content with an effective amount of an oxygen and SO2-containing gas in a reactor at an effective temperature to (i) provide elemental sulphur from the SO2, (ii) release exothermic heat, and (iii) produce a hot effluent gaseous steam containing the elemental sulphur and treated fuel having a second bound-sulphur content, (b) separating the elemental sulphur from the treated fuel; (c) collecting the elemental sulphur; (d) collecting the treated fuel; and (e) collecting the exothermic heat.

Abstract: A petroleum coke-based combined De-SOx and De-NOx process is described comprising use of four key units, namely, a flue gas concentrator (FC), a carbothermal reducer (CR), an elemental sulphur condenser (SC) and an oxidizer for reduced sulphur and nitrogen species (RO). The two major reactants in this process are the petroleum coke, preferably, and a flue gas containing SOx/NOx. The major products are elemental sulphur from the SC and activated coke from the CR. The process provides for SOx and NOx abatement in an economically viable way while the activated coke produced has a wide range of applications, particularly, in environmental protection.

Abstract: A process for the recovery of sulfur and carbon monoxide from metal sulfates in which the carbon monoxide is recycled as a reducing agent for reaction with the metal sulfate. Metal sulfates such as gypsum (calcium sulfate dihydrate) are processed to form sulfur dioxide. The sulfur dioxide is contacted with carbonaceous matter at sufficiently high temperature to form elemental sulfur and carbon monoxide. The carbon monoxide is then recycled for use as a reducing agent in the initial processing of the metal sulfate.

Abstract: Cement and elemental sulfur are produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfate hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln. Sulfur dioxide produced during the calcination is cooled and contacted with hydrogen and carbon monoxide to reduce the same to elemental sulfur.

Abstract: A dry, regenerable solid oxide process directed to convert SO.sub.x from the flue gas stream from a power plant, a coal or oil-fired plant or process heat furnace, or an FCC regenerator to elemental sulfur without using a Claus unit, a hydrogen plant, a regeneration gas separation system, or a hydrogenation section. This dry, regenerable solid oxide process is also effective on Claus plant tail-gas. This process uses solid oxides, such as, for example, magnesium aluminates or spinels to remove sulfur oxides from flue gas streams. The solid oxide is then regenerated by a reducing gas to release the sulfur compounds contained on the solid oxide to produce a gas stream comprising hydrogen sulfide, sulfur oxides and elemental sulfur. The elemental sulfur is then condensed and recovered as a product and the resulting gas stream may be recycled to be reprocessed over the solid oxide.

Abstract: There is provided a process directed to the use of gases containing or mixed with carbon monoxide, such as synthesis gas, to aid in the regeneration of sulfur oxide-sorbed solid oxides, such as magnesium aluminates or spinels. This process is especially useful in applications where the solid oxide is used to purify the flue gas stream from an FCC regenerator, coal or oil-fired plant, power plant or process heat furnace, or the tail gas from a Claus plant. The process is also useful to remove sulfur oxides from flue gases produced in solid fuel combusters. According to this invention, carbon monoxide may be used alone or in combination with other gases to make the regeneration of the solid oxide exothermic or less endothermic, thereby improving the effectiveness of the regeneration.

Abstract: A method for the continuous reduction of sulphur dioxide-containing gases essentially free of molecular oxygen, using coal or carbon, which comprises introducing the sulphur dioxide-containing gases into a coal-filled or carbon-filled reactor divided into at least three temperature zones, the temperature of which continuously increases in the direction of flow, including an inlet zone at a temperature of 150.degree. to 200.degree. C., a middle zone having a temperature of 300.degree. to 700.degree. C. and an outlet zone having a temperature of 900.degree. to 1100.degree. C. and passing the sulphur dioxide-containing gases through the zones so that the gases are heated to a final temperature of about 900.degree. to 1100.degree. C. in the outlet zone of the reactor and the sulphur dioxide is reduced to sulfur in the individual temperature zones. In a preferred embodiment, the sulphur dioxide-containing gases are introduced into a reactor having four temperature zones.

Abstract: Novel sorbents comprising (a) an alumina substrate having a pore volume between 0.4 and 0.8 cc/g, and (b) an alkali or alkaline earth component, for example, sodium carbonate, wherein the amount of the alkali or alkaline earth component is between 50 and 400 .mu.g per m.sup.2 of the substrate. The sorbents of the present invention are outstandingly effective for the removal of nitrogen oxides, sulfur oxides and hydrogen sulfide from waste gas streams.

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: Sulphur is manufactured out of sulphur dioxide containing gases by dividing the feed gas in two flows of gas having a volume ratio of 2 to 1 and reducing the greater flow of gas on a carbon containing substance like anthracite, thereby obtaining hydrogen sulfide which is mixed with the smaller flow of gas, the mixture being converted in a Claus process to sulphur.

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: An improved method for the recovery of elemental sulfur(S) from a coal-gas containing hydrogen sulfide (H.sub.2 S) wherein hot lime (CaO) is used and then regenerated according to the following chemistry:CaO+H.sub.2 S=CaS+H.sub.2 OCaS+3/2 O.sub.2 =CaO+SO.sub.2SO.sub.2 +C=S+CO.sub.2These chemical reactions are conducted in-situ while the supply of carbon (C) for the formation of the elemental sulfur(S) is derived from a component of the coal-gas itself to increase the overall efficiency of desulfurization, increase the uniformity of the carbon deposit into the hot lime (CaO), and eliminate the extra and cumbersome steps of physically moving the spent lime (CaO) for regeneration and returning it after regeneration, and the step of adding coal to react with the sulfur dioxide (SO.sub.2) formed as an off-gas during regeneration.

Abstract: A process for preparing a gas stream containing sulfur dioxide and water for reaction with coal to convert the sulfur dioxide to gaseous elemental sulfur. Water is initially removed from the gas stream to increase the percentage of sulfur dioxide in the stream after which the gas stream is passed through the flame of a burner to add combustion gases to the gas stream. Steam is then mixed with the gas stream to increase the percentage of water in the gas stream before it is reacted with the coal.

Abstract: A process for production of sulfur from SO.sub.2 -containing gas is disclosed comprising the steps of contacting said SO.sub.2 -containing gas mixed with additional oxygen or air, with carbonaceous materials, in a SO.sub.2 reduction reactor under elevated temperatures to thereby produce a first gaseous mixture containing vaporous sulfur, H.sub.2 S, COS and unreacted SO.sub.2 ; separating said vaporous sulfur by condensation from the first gaseous mixture to thereby obtain a second gaseous mixture; introducing the second gaseous mixture into a Claus reactor to thereby obtain a third gaseous mixture containing a vaporous sulfur produced by Claus reaction; separating said vaporous sulfur by condensation from the third gaseous mixture to thereby obtain a fourth gaseous mixture of reduced sulfur compound content; and recovering the sulfur separated from said first and third gaseous mixtures, the improvement comprising regulating the amount of oxygen or air mixed with the SO.sub.

Abstract: SO.sub.2 -containing gas is made to contact a carbon-containing material to reduce the gas to a gas mixture containing sulfur and also containing H.sub.2 S and SO.sub.2 in a volume ratio of 2:1. The sulfur is then removed by condensation and the remaining gas mixture subjected to a Claus-process treatment to obtain additional sulfur from it.

Abstract: A process for recovery of sulfur from SO.sub.2 -containing gas which comprises the steps of supplying said SO.sub.2 -containing gas mixed with additional oxygen to a SO.sub.2 reduction reactor filled with solid carbonaceous materials for reducing part of the SO.sub.2 into H.sub.2 S, a vaporous sulfur and COS; separating said vaporous sulfur by condensation from an effluent gas coming from this SO.sub.2 reduction reactor to thereby produce a first gaseous mixture; supplying this first gaseous mixture to a Claus reactor to further produce a vaporous sulfur by Claus reaction; separating said vaporous sulfur by condensation from an effluent gas coming from this Claus reactor to thereby produce a second gaseous mixture; measuring the concentrations of SO.sub.2 and H.sub.2 S in this second gaseous mixture and further the concentration of COS as occasion demands; and controlling the amount of oxygen supplied to the SO.sub.2 - containing gas introduced into said SO.sub.

Abstract: Sulfur oxides contained in the flue gas from coal-fired boiler are adsorbed by an adsorbent prepared by dry-distilling a portion of fuel coal, thereby producing semi-coke, and activating the semi-coke by steam, and then the sulfur oxides-adsorbed adsorbent is heated to desorb the adsorbed sulfur oxides at a high concentration. The desorbed sulfur oxides are passed through a bed of semi-coke before the activation to recover the sulfur oxides as elemental sulfur.

Abstract: Sulfur oxides contained in the flue gas from coal-fired boiler are adsorbed by an adsorbent prepared by dry-distilling a portion of fuel coal satisfying at least one of requirements of an ash content lower than 15% by weight and a fixed carbon content of at least 50% by weight, thereby producing semi-coke, and activating the semi-coke by steam, and then the sulfur oxides-adsorbed adsorbent is heated to desorb the adsorbed sulfur oxides at a high concentration. The desorbed sulfur oxides are passed through a bed of semi-coke before the activation to recover the sulfur oxides as elemental sulfur.

Abstract: Sulfur dioxide is converted to elemental surfur by reduction with a carbonaceous material in a reaction zone containing a molten salt. Heat is provided by reacting a portion of the carbonaceous material with oxygen. In a preferred embodiment alkali metal sulfates present in the molten salt are reduced to alkali metal sulfides.

Abstract: A continuous process for the reduction of sulfur dioxide to sulfur in which a gas stream containing sulfur dioxide is contacted with a carbon source in the form of particulate coal at a temperature of at least 600.degree. C. in a plasma arc reaction zone generated by a rotating direct current arc.

Abstract: There is provided a method for converting sulfur dioxide in an exhaust gas to sulfur, which comprises the reduction step of reducing sulfur dioxide in an exhaust gas containing water vapor to hydrogen sulfide in the presence of carbon, a part of the exhaust gas is caused to bypass the reduction step and the remainder of the exhaust gas is fed to the reduction step to convert sulfur dioxide in the exhaust gas to hydrogen sulfide; the gas from the reduction step is mixed with the exhaust gas bypassing the reduction step while controlling the amount of the bypassing exhaust gas so that the ratio of hydrogen sulfide to sulfur dioxide in the mixed gas is maintained at 2; the mixed gas is fed to the Claus reaction step; and the Claus reaction step of reacting hydrogen sulfide formed at the reduction step with sulfur dioxide to convert hydrogen sulfide to sulfur.

Abstract: A process for removing sulfur dioxide from an off-gas and converting it to elemental sulfur wherein steam is introduced into a sulfur dioxide-containing off-gas, and the composite is passed through a reactor containing a mixture of fresh and recycled coal.

Abstract: There is disclosed a multi-stage process for reducing sulfur dioxide to sulfur or to hydrogen sulfide whereby a hydrogen-containing gas from a high temperature gasifier is used. In the first stage of the process, the gasifier exit gas is contacted at a minimum temperature of about 1800.degree. F. with recycle gas containing SO.sub.2, H.sub.2 S, COS, mercaptans, and CS.sub.2 in order primarily to reduce the organic sulfur compounds, i.e., COS, mercaptans, and CS.sub.2, which heretofore would tend to accumulate in prior known methods employing a carbonaceous fuel for the reduction of SO.sub.2. Gas leaving the first stage is then sent to a second stage wherein SO.sub.2 from an external source is added. Reduction of sulfur dioxide occurs in the second stage at a temperature of about 2000.degree. F. minimum, with the surplus heat of reaction removed by the generation of steam. Gas leaves the second stage and is thereafter cooled with simultaneous generation of steam and selective condensation of sulfur vapor.

Abstract: Heavy oil from underground oil sands or tar sands is liquified with recirculation of superheated water and when brought to the ground surface is then wet oxidized for its heat value. The sulphur content of the products of wet oxidation is then wet reduced to elemental sulphur for by-product. The carbon dioxide gas generated as a product of wet oxidation is injected back to wells for its value as a diluter of the oil. Heat produced from wet oxidation is used for useful work at wells site.

Abstract: A process for removing SO.sub.x pollutants from a stack gas by (1) absorbing the SO.sub.x pollutants with 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 an aqueous absorbent of an iron(II) chelate, such as a chelate of ferrous ion with ethylenediaminetetraacetic acid. Regeneration of 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 sulfur and nitrogen without the discharge of waste solids.

Abstract: A gas desulfurization process is disclosed wherein a particulate, partially oxidized coal is used as an adsorbent for gaseous sulfur oxides and is regenerated by contact with a low temperature recycled stream of its own desorbed off-gas containing at least 40% steam and 15% SO.sub.2. A bleed stream of the desorbed off-gas may be reacted with coal at 1150.degree. F. to 1550.degree. F. to partially oxidize the coal and transform it into an adsorbent suitable for use in the adsorber.

Abstract: A system for reducing sulfur dioxide in which a vessel is provided with an inlet for receiving coal and a plurality of gas distribution nozzles for receiving the sulfur dioxide and discharging same downwardly in the lower portion of the vessel for flowing upwardly in a counterflow relation to the coal. The coal flows through a distribution device located in the hopper section of the vessel for insuring an even distribution of coal through the vessel.

Abstract: A liquid or solid hydrocarbon is partially oxidized in the presence of steam and oxygen in a high temperature reducing flame zone to which at least sulfur dioxide is added to consume generated hydrogen and carbon monoxide formed in a second flame zone to form hydrogen sulfide as necessary for a Claus reaction. Elemental sulfur is thermally formed. The gas stream is rapidly cooled to prevent further reactions, then further cooled to condense sulfur. The resultant gas stream is passed to one or more Claus conversion zones where hydrogen sulfide and sulfur dioxide react to form sulfur.

Abstract: A method for producing sulfur from sulfur dioxide. In the broadest embodiment, sulfur is produced by reducing the sulfur dioxide with a reducing gas comprising one or more lower, monohydric alcohols. The reduction may be accomplished either thermally or catalytically and the principal products obtained will be elemental sulfur and/or hydrogen sulfide, depending principally upon the particular conditions and relative reactive concentrations actually employed and in some cases, at least, some carbon oxysulfide will be produced. In the broadest embodiment, the reduction, and hence, the sulfur production will be accomplished in a single stage. In the more preferred embodiments, however, the production will be accomplished in a plurality of stages and, in a most preferred embodiment, the sulfur dioxide is first contacted with methanol under conditions such that the molar ratio of the hydrogen sulfide and carbon oxysulfide actually produced to the unconverted sulfur dioxide is within the range from about 1.

Abstract: A pollution control system and method in which sulfur oxides in flue gases are adsorbed by activated char in a gas-solid contacting device. The saturated char is regenerated in an integrated desorption-reduction vessel, to which crushed coal and combustion-supporting air are supplied. A portion of the crushed coal is burned to provide the heat for the regeneration of the char, resulting in the formation of sulfur dioxide and carbon dioxide gases, and the chemical consumption of a portion of the char. The remaining crushed coal reduces the sulfur dioxide to gaseous sulfur, and results in a material having a porous system suitable for use in the adsorption of sulfur oxides. The remaining regenerated char and the oxidized coal are cycled back to the gas-solid contacting device, and the gaseous sulfur is condensed to liquid in a condenser.

Abstract: An improved process for the reduction of SO.sub.2 is provided in which a gas containing SO.sub.2 is contacted with granular coal in the presence of steam.

Abstract: The present invention relates to a method of processing residual gases containing sulfur, hydrogen sulfide, and sulfur oxides and supplied from Claus plants or other surfur-producing installations, wherein the Claus plant is operated along or in connection with an ammonia decomposition plant in which ammonia-containing heated gases are directed through a decomposition zone which is free or filled with heat-resistant filler bodies or with a catalyst material, and the ammonia is decomposed into nitrogen and hydrogen and, thereupon, the gases are cooled and washed. The residual gases containing sulfur, hydrogen sulfide, sulfur oxides and ammonia-containing heated gases are fed to an ammonia decomposition chamber where the ammonia is decomposed into nitrogen and hydrogen and the residual gases react to produce a product gas enriched in hydrogen sulfide, the hydrogen for the reaction being supplied by the decomposition of ammonia.

Abstract: Sulfur dioxide in sulfur dioxide-containing gases is thermally reduced at relatively moderate temperatures under reducing conditions provided by the incomplete combustion of hydrocarbon to produce elemental sulfur. Elemental sulfur can be recovered from the effluent gases from the thermal reduction and the effluent gases may be treated by conventional catalytic processes to recover additional elemental sulfur from the remaining sulfur values.

Abstract: In accordance with the invention sulfur dioxide in sulfur dioxide-containing gases is converted under selective conditions to provide elemental sulfur in an efficient and economically-acceptable manner for present day industrial operations. The conversion involves the thermal reduction of sulfur dioxide in a zone at relatively moderate temperatures maintained by the combustion of carbonaceous fuel in the zone to provide elemental sulfur and to provide a gaseous thermal reduction effluent which is acceptable for further processing to recover additional sulfur values therefrom.

Abstract: A process for thermally treating fine-grained solids with high-oxygen gases at temperatures at which the solids can form molten and gaseous reaction products comprises carrying out the thermal treatment at least in part in a cyclone chamber. The solids, high-oxygen gases and, if desired, an energy carrier (usually a carbon-containing solid, liquid or gas) are mixed to form a suspension at a temperature below the reaction temperature. The suspension is fed to a vertical combustion path (tube) and reacts therein to form another suspension of primarily molten particles which is admitted to the cyclone chamber. Reactants are added to the gas phase within a core-flow region of the cyclone chamber and/or immediately after the discharge of gas therefrom to a cooling chamber.

Abstract: A system for reducing sulfur dioxide to elemental sulfur in which a reactor vessel is divided into a plurality of compartments, and coal is fed from a single source into each of the compartments. A sulfur dioxide rich gas is distributed to each of the compartments and is contacted with the coal to form substantially pure sulfur.

Abstract: A process is described for producing sulfur by the reaction of sulfur dioxide with agglomerating coal. The purity of the product gases is improved and the tendency of the coal to agglomerate is reduced by employing coal particles having a particle size below 500 microns.

Abstract: A process for producing a fuel gas and sulfur from a hydrocarbon fuel wherein a fuel oil containing sulfur is at least partially combusted in a fluidized bed of sorbent material which produces a substantially sulfur free fuel gas and a sulfided sorbent. The sulfided sorbent is passed to a second fluidized bed which regenerates the sulfided sorbent and produces a sulfur dioxide containing gas. The latter gas is contacted with granular coal in the presence of steam to reduce the sulfur dioxide to elemental sulfur.

Abstract: A process is disclosed whereby NO.sub.x and SO.sub.x components contained in stack gases are simultaneously reduced to N.sub.2 and H.sub.2 S, respectively, by passing said stack gases (which also contain steam and usually some oxygen) over bituminous coke at between about 900.degree. and 1600.degree. F.

Abstract: Elementary sulfur is obtained from sulfur-containing materials which release sulfur oxides (SO.sub.x) in the presence of oxygen by fluidizing such materials in a bed with an oxygen-containing gas (e.g., air), and passing the resulting SO.sub.x -containing gases through a bed (preferably fluidized) of carbonaceous or carbon-containing solids (such as coke or coal) at an elevated temperature to reduce SO.sub.x to elemental sulfur, the bottom of the bed of carbonaceous or carbon-containing solids being at about the level of the top of the bed of sulfur-containing materials.

Abstract: Sulfur dioxide is reduced to sulfur and hydrogen sulfide with a gaseous reducing agent in the presence of a catalyst by a process involving mixing a sulfur dioxide-containing gas stream with a portion of the gaseous reducing agent and passing the resulting mixture through a first reactor to effect reduction of a portion of the sulfur dioxide to hydrogen sulfide and sulfur, mixing the gas stream from the first reactor with the remaining gaseous reducing agent, and splitting the resulting mixture into two gas streams which are in parallel passed through a second and third reactor to effect reduction of sulfur dioxide to form hydrogen sulfide and sulfur. Periodically, the flow in the first and third reactors is reversed to thereby subject these reactors to periodically alternating heat absorbing and desorbing cycles while the flow in the second reactor is always maintained in the same direction.

Abstract: A method is disclosed for treating flue gas and the like for sulfur dioxide removal and sulfur recovery. The flue gas, containing a minor but polluting amount of sulfur dioxide, is contacted with ammonia in a reaction chamber. The reaction product is caused to precipitate onto a heat sink where it is mechanically removed on a continuous basis. The removed compounds are recycled by subjecting them either in solid or vaporized form to carbon monoxide between 140.degree. F and 600.degree. F to obtain sulfur and ammonia.