Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8603—Removing sulfur compounds
  • B01D53/8612—Hydrogen sulfide
  • B01D53/8615—Mixtures of hydrogen sulfide and sulfur oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
  • B01D53/86—Catalytic processes
  • B01D53/8603—Removing sulfur compounds
  • B01D53/8609—Sulfur oxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • B01J21/063—Titanium; Oxides or hydroxides thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
  • B01J35/31—Density
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/61—Surface area
  • B01J35/615—100-500 m2/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/633—Pore volume less than 0.5 ml/g
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J35/00—Catalysts, in general, characterised by their form or physical properties
  • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
  • B01J35/63—Pore volume
  • B01J35/635—0.5-1.0 ml/g
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B17/00—Sulfur; Compounds thereof
  • C01B17/02—Preparation of sulfur; Purification
  • C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
  • C01B17/0473—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by reaction of sulfur dioxide or sulfur trioxide containing gases with reducing agents other than hydrogen sulfide
  • C01B17/0486—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by reaction of sulfur dioxide or sulfur trioxide containing gases with reducing agents other than hydrogen sulfide with carbon monoxide or carbon monoxide containing mixtures

Definitions

• the present invention relates to a method for removing sulphur dioxide from gaseous effluent, wherein a mixture of gaseous outlet gasses or gaseous effluent includes sulphur dioxide and carbon monoxide, and wherein, to perform a catalytic reduction, a catalyst is used to catalyse a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur.
• the invention also relates new uses of catalysts, in particular to new uses of titanium dioxide as a catalyst.
• said catalysts do not promote hydrogenation reactions or the reaction of carbon monoxide and water (the shift reaction).
• such catalysts do promote the reaction of hydrogen sulphide and sulphur dioxide (the "Claus" reaction) and/or the hydrolysis of carbon-sulphur compounds.
• the invention also provides methods and reactors comprising said catalysts.
• Sulphur dioxide is a typical by-product of industrial processes such as the smelting of sulphide ores or burning of sulphur containing fuels. If vented to the atmosphere without treatment, it can cause environmental problems such as acid rain.
• UK 1213760.0 discloses a process for producing sulphur from sulphur dioxide using thermal reduction with natural gas which has been successfully demonstrated on an industrial scale unit.
• This process operates with high sulphur recovery efficiency and is efficient in the overall use of natural gas if a high temperature incinerator is needed downstream of the process.
• Such a high temperature incinerator can use the fuel values in the process gas as fuel.
• Alternative processes have been proposed which use a hydrogenation catalyst following the thermal stage in order to react the reducing gases with sulphur dioxide.
• the present invention provides the use of a catalyst comprising at least 90 % by weight of titanium dioxide to catalyse a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur to remove sulphur dioxide from gaseous effluent.
• a catalyst comprising at least 90 % by weight of titanium dioxide to catalyse a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur to remove sulphur dioxide from gaseous effluent.
• the gaseous effluent of a smelter typically, the gaseous effluent of a smelter.
• the catalyst comprises at least 95 % by weight of titanium dioxide, preferably at least 99.5 % by weight titanium dioxide, preferably the catalyst consists essentially of titanium dioxide, preferably the catalyst consists of titanium dioxide.
• catalyst composition weight percentages are measured on a dry basis.
• a majority, more preferably substantially all, of the carbon monoxide is consumed by the reaction.
• the catalysis occurs (is performed) at a temperature below 450 °C , preferably from about 350 °C to about 420 °C, more preferably not higher than about 390 °C. It has been found that there is a sharp increase in the conversion of carbon monoxide at temperatures above 350 °C, whereas at temperatures below 420°C, little or no reaction between hydrogen and sulphur dioxide occurs.
• the gaseous effluent further comprises hydrogen and preferably substantially none of the hydrogen is consumed (e.g. react with sulphur dioxide).
• the gaseous effluent comprises hydrogen sulphide and the catalyst simultaneously performs the Claus reaction.
• catalysis is performed before a subsequent catalytic stage wherein said subsequent catalytic stage is a first catalytic stage from the Claus process.
• the present invention provides the use of a catalyst, preferably titanium dioxide, to simultaneously catalyse a reaction between sulphur dioxide and carbon monoxide to produce carbon dioxide and sulphur and a reaction between hydrogen sulphide and sulphur dioxide to produce sulphur and water.
• a catalyst preferably titanium dioxide
• the present invention provides the use of a catalyst, preferably titanium dioxide, to simultaneously catalyse a reaction between sulphur dioxide and carbon monoxide to produce carbon dioxide and sulphur and a reaction between hydrogen sulphide and sulphur dioxide to produce sulphur and water.
• a catalyst preferably titanium dioxide
• the present invention provides the use of a catalyst, preferably titanium dioxide, to simultaneously catalyse a reaction between sulphur dioxide and carbon monoxide to produce carbon dioxide and sulphur and a reaction between hydrogen sulphide and sulphur dioxide to produce sulphur and water.
• the catalyst comprises at least 90 % by weight of titanium dioxide, more preferably at least 95 % by weight of titanium dioxide, preferably at least 99.5 % titanium dioxide, preferably the catalyst consists essentially of titanium dioxide, preferably the catalyst consists of titanium dioxide. Again, weight percentages are measured on a dry basis.
• the catalysis occurs at a temperature from about 350 °C to about 450 °C, more preferably from about 350 °C but not higher than about 420 °C, more preferably not higher than about 390 °C.
• catalysis is performed before a subsequent catalytic stage wherein said subsequent catalytic stage is a first catalytic stage from the Claus process.
• the present invention provides the use of titanium dioxide to catalyse a reaction between sulphur dioxide and carbon monoxide to produce carbon dioxide and sulphur at a temperature less than about 450 °C, preferably from about 350 °C to about 420 °C, more preferably not higher than about 390 °C.
• a majority, more preferably, at least about 75 % by weight of the carbon monoxide is consumed by the reaction, more preferably at least about 90 % by weight, even more preferably at least about 95 % by weight, more preferably substantially all.
• the titanium dioxide simultaneously catalyses a reaction between hydrogen sulphide and sulphur dioxide to produce sulphur and water.
• the catalyst promotes the Claus reaction and hydrolysis of carbon-sulphur compounds without significantly promoting hydrogenation or shift reactions.
• the present invention provides a method for removing sulphur dioxide from gaseous effluent, preferably the gaseous effluent of a smelter furnace, by performing a catalytic reduction: wherein the gaseous effluent includes sulphur dioxide and carbon monoxide, and wherein the catalytic reduction is performed using a catalyst, preferably titanium dioxide, to catalyse a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur.
• a catalyst preferably titanium dioxide
• the effluent also contains hydrogen sulphide and the titanium dioxide simultaneously catalyses a reaction between hydrogen sulphide and sulphur dioxide to produce sulphur and water.
• the catalyst promotes the Claus reaction and hydrolysis of carbon-sulphur compounds without significantly promoting hydrogenation or shift reactions.
• the method comprises the steps of:
• the method comprises the steps of:
• Reacting sulphur dioxide with carbon monoxide has the significant advantage of reducing the requirement for complete reduction of sulphur dioxide during the thermal reduction step. This significantly reduces the consumption of natural gas (i.e. by up to 5 %); thereby significantly reducing the cost of the process.
• the thermal reaction may be operated with a higher proportion of air or oxygen; thereby burning more hydrogen sulphide to form sulphur dioxide in the furnace. This increases the temperature; thereby reducing fuel use and the risk of soot formation.
• Preferably following the catalytic reduction substantially no carbon monoxide remains.
• the catalytic reduction step is performed in a reactor having a reactor inlet for receiving the mixture of gaseous outlet gases and a reactor outlet for expelling a gaseous mixture including the products of the catalytic reduction step.
• the temperature of the mixture of the gaseous mixture at the outlet is greater than about 350 °C, preferably greater than 350°C but below about 450 °C, preferably between about 350 °C and about 420 °C, preferably from about 350 °C to about 390 °, more preferably at about 370 °C.
• the inlet temperature of the invention similar to those that are typical for the first catalytic stages of known Claus processes.
• the temperature at the outlet is higher than is typical for the first catalytic stages of known Claus processes. In embodiments, it is preferred that the temperature does not exceed about 390 °C, or even 350 °C, because above this temperature sulphur conversion by the Claus reaction drops and construction materials other than carbon steel must be used.
• the outlet temperature typically reflects the temperature of the catalyst.
• the catalysis is performed at a temperature less than about 450 °C, preferably from about 350 °C to about 420 °C.
• the catalytic reaction is performed at pressures typical of an industrial Claus unit.
• the catalyst comprises at least 90 % by weight of titanium dioxide, preferably at least about 95 % by weight, preferably at least 99.5 % by weight of titanium dioxide (measured on a dry basis), preferably the catalyst consists essentially of titanium dioxide, preferably the catalyst consists of titanium dioxide.
• the catalyst does not significantly catalyse
• the catalyst does not significantly catalyse a reaction between hydrogen and sulphur and/or the reaction between carbon monoxide and water.
• the catalyst does not significantly catalyse any of these reactions.
• the catalyst is a hydrolysis catalyst for carbonyl sulphide and/or carbon bisulphide and/or is a Claus catalyst for the reaction of hydrogen sulphide and sulphur dioxide to form sulphur and water.
• the catalyst has a surface area of at least about 200 m 2 /g, preferably at least about 240 m 2 /g.
• the catalyst has a bulk density of from about 650 kg/m 3 to about 1000 kg/m 3 , preferably from about 750 to about 800 kg/m 3 .
• the catalyst has a total pore volume (Hg) of from about 0.3 to about 0.65 cm 3 /g, preferably from about 0.50-0.6 cm 3 /g.
• Hg total pore volume
• Suitable catalyst is sold under the trade name S-7001 from Euro Support B.V.
• the thermal reduction process comprises the step of reacting sulphur dioxide and a fuel gas in a furnace, preferably wherein the heat required for performing the reaction is provided by combusting the fuel gas with oxygen.
• the oxygen may be pure or present in air.
• Suitable fuel gases may be selected from the group consisting of methane, ethane, propane, carbon monoxide or mixtures thereof, or gases high in methane, such as natural gas.
• substantially only sulphur dioxide, fuel gas, and oxygen or air are supplied to the furnace.
• substantially no hydrogen sulphide or sulphur is supplied to the furnace.
• the fuel gas for reducing the sulphur dioxide is heated by combusting the fuel gas with oxygen.
• the fuel gas and sulphur dioxide are heated to a temperature of at least about 1000 °C, preferably at least about 1100 °C, more preferably at least about 1250 °C, preferably from about 1200 °C to about 1400 °C, preferably from about 1000 °C to about 1500 °C.
• step a) the effluent undergoes an absorption and regeneration process in order to provide sulphur dioxide for thermal reduction in step a); preferably, separating the sulphur dioxide from the remainder of the gaseous effluent provides concentrated sulphur dioxide and effluent suitable for discharge into the atmosphere.
• concentrated sulphur dioxide is produced by using an absorption and regeneration process.
• Typical absorption and regeneration processes include, but are not limited to, carbon bed, solvent and chemical base processes, including amine gas treatment. Such processes and equipment for performing sulphur dioxide absorption and regeneration process are known in the art.
• the fuel supported Claus reaction comprises the step of partially reacting hydrogen sulphide with oxygen, preferably wherein heat is provided by combusting a fuel gas with the oxygen.
• the oxygen may be pure or present in air.
• Suitable fuel gases may be selected from the group consisting of, methane, ethane, propane, carbon monoxide or mixtures thereof, or gases high in methane, such as natural gas.
• hydrogen sulphide, oxygen and fuel gas are supplied to the furnace, although the other gasses including sulphur dioxide may also be present.
• the hydrogen sulphide may be from the effluent of a refinery or gas treating process.
• the hydrogen sulphide and oxygen are heated by combusting the fuel gas with oxygen and only partly by the combustion of hydrogen sulphide.
• the hydrogen sulphide and oxygen are heated to a temperature of at least about 1000 °C, preferably at least about 1100 °C, preferably from about 1000 °C to about 1300 °C.
• the present invention provides the use of a catalyst which catalyses a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur to remove sulphur dioxide from gaseous effluent, preferably the gaseous effluent of a smelter or the mixture of outlet gasses from a fuel supported Claus reaction, by reacting carbon monoxide with sulphur dioxide to produce carbon dioxide and sulphur.
• the catalytic reduction reactor also caries out the Claus reaction (between hydrogen sulphide and sulphur dioxide to make sulphur and water) and hydrolysis of carbon-sulphur compounds.
• the ratio of reactants in the furnace is arranged to obtain about a 2: 1 H2S:S02 ratio in the process gases after hydrolysis of the carbon-sulphur species, (i.e in the tail gases following the final Claus reactor).
• the present invention provides a catalytic reactor for removing sulphur dioxide from an effluent gas mixture.
• the catalytic reactor comprises a reactor chamber having an inlet for receiving the effluent gas mixture and an outlet for expelling a gaseous product mixture; and a catalyst bed located within said reactor chamber, said catalyst bed comprising a catalyst, typically titanium dioxide.
• the effluent gas mixture comprises sulphur dioxide and carbon monoxide, and the catalyst catalyses a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur.
• the effluent gas mixture passes over and/or through the catalyst bed such that the sulphur dioxide and carbon monoxide can mix and react.
• the effluent gas mixture is a mixture of gaseous outlet gasses produced by performing a thermal reduction step on sulphur dioxide from smelter effluent, preferably wherein the smelter effluent has undergone a process to provide concentrated sulphur dioxide, said thermal reduction step being performed on the concentrated sulphur dioxide.
• the effluent gas mixture is a mixture of gaseous outlet gasses produced by performing a fuel supported Claus reaction.
• the catalytic reactor inlet is in fluid communication with a furnace performing a thermal reduction step, preferably wherein the thermal reduction step comprises combusting sulphur dioxide in the presence of a fuel gas and oxygen.
• the thermal reduction step comprises the step of reacting sulphur dioxide, a fuel gas and oxygen in a furnace.
• the oxygen may be pure or present in air.
• Suitable fuel gases may be selected from the group consisting of methane, ethane, propane, carbon monoxide or mixtures thereof, or gases high in methane, such as natural gas.
• the fuel gas for reducing the sulphur dioxide is heated by combusting the fuel gas with oxygen.
• the fuel gas and concentrated sulphur dioxide are heated to a temperature of at least about 1000 °C, preferably at least about 1100 °C, more preferably at least about 1250 °C, preferably from about 1200 °C to about 1400 °C, preferably from about 1000 °C to about 1500 °C.
• the catalytic reactor inlet is in fluid communication with a furnace for performing a fuel supported Claus reaction, preferably wherein the fuel supported Claus reaction comprises the step of reacting hydrogen sulphide with oxygen, preferably wherein heat is provided by combusting a fuel gas with the oxygen.
• the oxygen may be pure or present in air.
• Suitable fuel gases may be selected from the group consisting of methane, ethane, propane, carbon monoxide or mixtures thereof, or gases high in methane, such as natural gas.
• hydrogen sulphide, oxygen and fuel gas are supplied to the furnace, although the other gasses including sulphur dioxide may also be present.
• the hydrogen sulphide may be from the effluent of a refinery or gas treatment.
• the hydrogen sulphide and oxygen are heated by combusting the fuel gas with oxygen.
• the hydrogen sulphide and oxygen are heated to a temperature of at least about 1000 °C, preferably at least about 1100 °C, preferably from about 1000 °C to about 1300 °C.
• the outlet of the catalytic reactor is in fluid
• the temperature of the effluent gas mixture at the catalytic reactor inlet is less than about 250 °C and/or the temperature of the gases at the outlet is greater than about 300 °C but below about 390 °C.
• the temperature within the reactor does not exceed about 390 °C, more preferably below about 350 °C.
• the temperature within the reactor is greater than about 350 °C, preferably greater than about 350 °C but below 450 °C; preferably the temperature is from about 350 °C to about 420 °C, preferably from about 350 °C to about 390 °C, more preferably the temperature is about 370 °C.
• the pressure in the reactor is 0.1 bar(g) to 1.0 bar(g).
• the catalyst comprises a material selected from the group consisting of titanium dioxide, preferably the catalyst consists of titanium dioxide.
• a smelter comprising a catalytic reactor according to the sixth aspect of the invention.
• the smelter further comprises means for removing sulphur dioxide from gaseous effluent from the smelter so as to provide concentrated sulphur dioxide and effluent suitable for discharge into the atmosphere.
• the concentrated sulphur dioxide is produced by using an absorption and regeneration process.
• Typical absorption and regeneration processes include, but are not limited to, carbon bed, solvent and chemical base processes, including amine gas treatment. Such processes and equipment for performing sulphur dioxide absorption and regeneration process are known in the art.
• the smelter further comprises a furnace for performing a thermal reduction step on the concentrated sulphur dioxide, preferably wherein the thermal reduction step comprises combusting sulphur dioxide and oxygen in the presence of a fuel gas.
• the furnace is in fluid communication with the inlet of the catalytic reactor according to fourth aspect of the invention.
• the outlet of catalytic reactor is in fluid communication with a subsequent catalytic reactor for performing the first catalytic stage of the Claus process.
• Condensers for the removal of sulphur may be used between the furnace and the catalytic reactor and/or between the catalytic reactor and the subsequent catalytic reactor for performing the first catalytic stage of the Claus process.
• the smelter comprises a furnace for performing a fuel supported Claus reaction, preferably wherein the fuel supported Claus reaction comprises the step of reacting hydrogen sulphide with oxygen, preferably wherein part of the heat is provided by combusting a fuel gas with the oxygen.
• the furnace is in fluid communication with the inlet of the catalytic reactor according to sixth aspect of the invention.
• the outlet of catalytic reactor is in fluid communication with a subsequent catalytic reactor for performing the first catalytic stage of the Claus process.
• Condensers for the removal of sulphur may be used between the furnace and the catalytic reactor and/or between the catalytic reactor and the subsequent catalytic reactor for performing the first catalytic stage of the Claus process.
• the catalyst is substantially free from, preferably free from lanthanum, yttrium, gadolinium, lutetium, zirconium, aluminium, silicas, cobalt, molybdenum, tungsten, vanadium, chromium, nickel, iron and mixtures thereof, including their oxides.
• the catalyst is substantially free from, preferably free from, transition metals other than titanium.
• the catalyst temperature is such that a reaction between hydrogen and sulphur dioxide is avoided, whilst allowing the reaction of carbon monoxide with sulphur dioxide.
• the smelter aspect may include the catalytic reactor of the catalytic reactor aspect and/or employ the method and use aspects.
• Fig. 1 is a schematic of an exemplary process according to the invention
• Fig. 2 is a schematic of an alternative exemplary process according to the invention.
• FIG. 3 shows a catalytic reactor according the sixth aspect of the invention.
• the present invention provides a method for removing sulphur dioxide from gaseous effluent or a mixture of gaseous outlet gasses, preferably the gaseous effluent of a smelter furnace, by performing a catalytic reduction reaction, wherein the mixture of gaseous outlet gasses or effluent includes sulphur dioxide and carbon monoxide, and wherein the catalytic reduction is performed using a catalyst which catalyses a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur.
• the method comprises the steps of:
• the method comprises the steps of:
• Figure 1 shows a schematic representation of an exemplary process according to the invention.
• Thermal reduction of sulphur dioxide is performed in the furnace.
• the feed gasses for the furnace comprise a fuel gas, sulphur dioxide and air. Typically, substantially no other gasses are present in the feed gases.
• the sulphur dioxide is collected from the effluent of a smelter furnace.
• the effluent undergoes an absorption and regeneration process in order to provide sulphur dioxide for thermal reduction.
• separating the sulphur dioxide from the remainder of the smelter effluent provides concentrated sulphur dioxide and effluent suitable for discharge into the atmosphere.
• Typical absorption and regeneration processes include, but are not limited to, carbon bed, solvent and chemical base processes, including amine gas treatment. Such processes and equipment for performing sulphur dioxide absorption and regeneration process are known in the art.
• the air is collected from the surrounding environment. For the avoidance of doubt, it contains oxygen. Alternatively, pure oxygen or oxygen enriched air can be used. [076]
• the fuel gas is preferably natural gas, although it may also be selected from the group consisting of methane, ethane, propane, carbon monoxide or mixtures thereof.
• the fuel gas for reducing the sulphur dioxide is heated by combusting the fuel gas with oxygen.
• the fuel gas and sulphur dioxide are heated to a temperature of at least about 1000 °C, preferably at least about 1 100 °C, more preferably at least about 1250 °C, preferably from about 1200 °C to about 1400 °C, preferably from about 1000 °C to about 1500 °C.
• the products from the thermal reduction step flow from the furnace to waste heat boiler or condenser where they are cooled such that the sulphur formed in the reduction step condenses.
• the condensed sulphur is preferably removed.
• FIG. 3 illustrates a catalytic reactor (1) according to the invention.
• the catalytic reactor removes sulphur dioxide from effluent gas mixture.
• the effluent gas mixture is the mixture of gaseous products from the thermal reduction step with the sulphur removed, although, in alternative arrangements, the sulphur may be present.
• the effluent gas mixture entering the reaction chamber comprises sulphur dioxide and carbon monoxide, and the catalyst catalyses a reaction between carbon monoxide and sulphur dioxide to produce carbon dioxide and sulphur, preferably as well as promoting the Claus reaction and hydrolysis of carbon-sulphur compounds contained in the effluent gases from the furnace.
• the sulphur can be removed using a separate condenser.
• the sulphur remains gaseous while present in the reactor, so as to prevent fouling of the catalyst.
• the remaining hydrogen sulphide and sulphur dioxide in the outlet gasses are treated using the catalytic stages of a typical Claus process.
• the Claus process is well known to those skilled in the art, as are the catalytic steps conducted therein.
• the general formula for such catalysis is 2 H 2 S + S0 2 ⁇ 3 S + 2 H 2 0.
• the Claus process catalytic steps are used to increase sulphur recovery.
• the catalytic recovery of sulphur consists of three sub-steps: heating, catalytic reaction and cooling plus condensation. These three steps are normally repeated a maximum of three times. The more Claus reactors that are used, the better the recovery of sulphur from the process.
• incineration and a tail-gas treatment unit (TGTU) are used downstream of the Claus catalytic stages.
• TGTU tail-gas treatment unit
• the catalytic reactor (1) comprises a reactor chamber (2) and a catalyst bed (3).
• the reactor chamber (2) is lined with refractory cement.
• the catalyst bed (3) comprises a layer of catalyst (5) supported by inert refractory balls in turn supported by a stainless steel mesh (4, 8) resting on a support structure (not shown).
• the layer of catalyst (5) will be between about 500 mm and about 2000 mm deep, preferably between about 750 mm and 1500 mm deep, preferably between about 1000 mm and about 1200 mm deep.
• Baffles (6, 7) are used to improve the distribution of gases within the reaction chamber.
• the catalyst typically consists of titanium dioxide.
• the catalyst may be in the form of balls, pellets or extrudate.
• the catalyst has a surface area of at least about 200 m 2 /g, preferably at least about 240 m 2 /g.
• the catalyst has a bulk density of from about 650 kg/m 3 to about 1000 kg/m 3 , preferably from about 750 to about 800 kg/m 3 .
• the catalyst has a total pore volume (Hg) of from about 0.3 to about 0.65 cm 3 /g, preferably from about 0.50-0.6 cm 3 /g.
• Hg total pore volume
• Suitable catalyst is sold under the trade name S-7001 from Euro Support B.V.
• the reactor chamber (1) comprises an inlet (9) for receiving the effluent gas mixture and an outlet (10) for expelling a gaseous mixture including the products of the catalytic reduction step.
• the outlet (10) will typically be in fluid communication with a subsequent catalytic reactor chamber which performs the first subsequent catalytic step of the Claus process.
• a condenser may be positioned between the reactor chamber (1) of the invention and the subsequent Claus catalytic reactor which in use removes sulphur from the gaseous mixture including the products of the catalytic reduction step and Claus reaction occurring in the reactor of the invention.
• the inlet (9) will typically be in fluid communication with either the furnace for performing a sulphur dioxide thermal reduction or the furnace for a fuel supported Claus reaction or a condenser for removing sulphur from the gaseous products of the thermal reduction or fuel supported Claus reaction.
• Figure 2 show an alternative exemplary embodiment according to the second embodiment of the first aspect of the invention, including performing a fuel supported Claus reaction to produce sulphur and a mixture of gaseous outlet gasses.
• the catalytic reactor (1) shown in Figure 3 may be used in the process of Figure 2.
• the gas mixture fed to the catalytic reactor contained hydrogen sulphide, sulphur dioxide, carbon dioxide, nitrogen, carbon monoxide, hydrogen, carbonyl sulphide, carbon bisulphide, sulphur vapour and water vapour.
• the gas composition was such that there was an excess of H 2 S over S0 2 in the effluent gases from the catalyst, which is typical for industrial Claus plant operations.

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• 2014
  • 2014-03-03 EP EP14716371.1A patent/EP2961685A1/de not_active Withdrawn

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