Abstract: One aspect of the present invention relates to salts that are room-temperature ionic liquids (RTILs), methods of making them, and methods of using them in connection with temporary or permanent gas sequestration. Another aspect of the present invention relates to a class of solvents which can be transformed into RTILs by exposure to a gas, and methods of using them in connection with temporary or permanent gas sequestration.

Abstract: A method of modifying a chemical interaction between a functional group of an immobilized amine in a solid sorbent composition and a compound that chemically interacts with the functional group to reduce the heat required to desorb the compound from the solid sorbent. A method of inhibiting degradation of an immobilized amine in an immobilized amine solid sorbent. Compositions and methods of use of a low-cost regenerable immobilized amine solid sorbent resistant to degradation.

Abstract: The current invention describes methods and compositions of various sorbents based on aerogels of various silanes and their use as sorbent for carbon dioxide. Methods further provide for optimizing the compositions to increase the stability of the sorbents for prolonged use as carbon dioxide capture matrices.

Abstract: In an embodiment, a CO2 recovery system has an absorber, a regenerator, and a circulation device. An absorption liquid has an aqueous solution of amine having an alcohol group, and dimethyl silicone oil in which a part of methyl groups is substituted by at least one type selected from an aminoalkyl group, a carboxyl group, and a hydroxyl-containing alkyl group. The absorber contacts a combustion exhaust gas of a fossil fuel and the absorption liquid to absorb CO2, which is contained in the combustion exhaust gas, into the absorption liquid. The regenerator releases CO2 by applying thermal energy to the CO2-absorbed absorption liquid. A circulation device circulates the absorption liquid between the absorber and the regenerator.

Abstract: A process for workup of an industrial carbon dioxide-rich gas to be freed of sulfur components, in which an industrial gas to be freed of sulfur components is purified by a gas scrubbing, and the laden solvent is freed of carbon dioxide and hydrogen sulfide by a regeneration to obtain at least one acid gas fraction having a relatively high content of sulfur components, and the fraction with the highest hydrogen sulfide (H2S) content is supplied to a Claus plant with downstream Claus process gas hydrogenation, and at least one carbon dioxide-laden, low-hydrogen sulfide acid gas fraction from the regeneration device, which has a reduced sulfur content compared to the fraction with the highest hydrogen sulfide (H2S) content, is combined with the hydrogenated Claus process gas to give a combined process gas stream, which is supplied to further processing or to recycling into the process.

Abstract: The degradation of an absorbent solution comprising organic compounds provided with an amine function in aqueous solution is reduced considerably in the presence of a small amount of degradation inhibiting additives whose structure comprises a 5-atom heterocycle composed of a nitrogen atom, a sulfur atom or an oxygen atom, and 3 carbon atoms, at least one of which is joined to a sulfur atom not belonging to the ring. The absorbent solution is employed for deacidifying a gaseous effluent.

Abstract: A method and corresponding apparatus for separation of carbon dioxide from an exhaust gas of a fossil-fired power are provided. In an absorption process, the exhaust gas containing carbon dioxide is brought into contact with an absorption medium so that the absorption medium is laden with carbon dioxide. In a desorption process, vapor from a water/steam circuit of the fossil-fired power plant is heated, wherein a laden absorption medium is regenerated. In a subsequent expansion process, the regenerated absorption medium is expanded so that a vapor and an expanded absorption medium are formed, wherein the vapor is recirculated into the desorption process. The laden absorption medium is divided into a first part stream and a second part stream. Only the second part stream is brought into heat-exchanging contact with the expanded absorption medium. The first and second part streams are supplied to the desorption process at different process stages.

Abstract: This invention provides novel processes utilizing compositions comprising substituted polyamines as acid gas scrubbing solutions and methods of using the compositions in an industrial system. The invention relates to the use of such polyamine compounds in industrial processes to remove acidic contaminants from natural and industrial fluid streams, such as natural gas, combustion gas, natural gas, synthesis gas, biogas, and other industrial fluid streams. The compositions and methods of the invention are useful for removal, absorption, or sequestration of acidic contaminants and sulfide contaminants including CO2, H2S, RSH, CS2, COS, and SO2.

Abstract: A system and method for removing carbon dioxide from a gas stream. One aspect of the method includes introducing a carbon dioxide containing gas stream to an absorber; contacting the gas stream with an amine-containing solvent; absorbing, with the amine-containing solvent, the carbon dioxide from the gas stream, thereby removing the carbon dioxide from the gas stream; and forming a precipitate with the amine-containing solvent and the carbon dioxide.

Abstract: There is provided an acid gas absorbent having excellent performance of absorbing acid gas such as carbon dioxide, and an acid gas removal device and an acid gas removal method using the acid gas absorbent. An acid gas absorbent of an embodiment contains at least one type of tertiary amine compound represented by the following general formula (1). (In the above formula (1), the cycle A represents a cyclic structure whose carbon number is not less than 3 nor more than 8. R1, R2 and R3 each represent an alkyl group whose carbon number is 1 to 4, and R4 represents a hydroxyalkyl group. R1 and R2 are groups coupled to carbon atoms adjacent to a carbon atom forming the cycle A and coupled to a nitrogen atom.

Abstract: A CO2 recovery apparatus includes a desulfurization tower which includes a desulfurization unit and a cooling unit, an absorption tower which includes a CO2 absorption unit and an acid washing unit, a regeneration tower, and an acid water production device configured to produce acid water by causing exhaust gas yet to be introduced into the desulfurization to come into contact with water. In the CO2 recovery apparatus, the water to be come in contact with the exhaust gas is condensed water that is generated in the desulfurization tower, the absorption tower, or the regeneration tower.

Abstract: This invention provides novel compositions comprising substituted polyamines as acid gas scrubbing solutions and methods of using the compositions in an industrial system. The invention relates to the use of such polyamine compounds in industrial processes to remove acidic contaminants from natural and industrial fluid streams, such as natural gas, combustion gas, natural gas, synthesis gas, biogas, and other industrial fluid streams. The compositions and methods of the invention are useful for removal, absorption, or sequestration of acidic contaminants and sulfide contaminants including CO2, H2S, RSH, CS2, COS, and SO2.

Abstract: The present disclosure describes the efficient use of a catalyst, an enzyme for example, to provide suitable real cyclic capacity to a solvent otherwise limited by its ability to absorb and maintain a high concentration of CO2 captured from flue gas. This invention can apply to non-promoted as well as promoted solvents and to solvents with a broad range of enthalpy of reaction.

Abstract: A process for absorbing H2S and CO2 from a gas mixture containing both these gases comprises contacting the gas mixture with an absorbent combination of (i) primary absorbent component comprising a severely sterically hindered tertiary etheramine triethylene glycol alcohol or derivative of such an alcohol and (ii) secondary absorbent component for acidic gases comprising a liquid amine such as methyldiethylamine (MDEA), monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), piperazine (PZ), diethanolamine (DEA), triethanolamine (TEA), diglycolamine (aminoethoxyethanol, DGA) and diisopropylamine (DIPA) another etheramine alcohol or diamine. By using the combination of amine absorbents, the overall selectivity of CO2 pickup can be maintained while retaining good H2S sorption selectivity; the selectivity of the combination for H2S and CO2 may be controlled over a range of gas loadings in the absorbent.

Abstract: The disclosure pertains to removal of carbon dioxide from industrial gas streams. Processes and systems are disclosed for capturing carbon dioxide from a combustion flue gas or from uncombusted natural gas by contacting with an amine blend in a first step, and an advanced solvent in a second step.

Abstract: A process for the selective separation of hydrogen sulfide from gas mixtures containing carbon dioxide as well as other acidic gases uses severely sterically hindered amino alcohol absorbents based on amino alcohols and ethers containing secondary nitrogen atoms hindered by an alpha tertiary carbon atom. Preferred absorbents include 2-(N-methylamino)-2-methylpropan-1-ol, (2-(N-ethylamino))-2-methylpropan-1-ol, (2-(N-isopropylamino)-2-methylpropan-1-ol, SBAE (2-(N-sec-butylamino)-2-methylpropan-1-ol) and (2-(N-t-butylamino)-2-methylpropan-1-ol.

Abstract: A modular amine plant having a front-end module and a back-end module in fluid communication with each other. The front-end module having pre-fabricated connections for the association of various equipment including: a filter, an absorption tower, and a flash tank. The back-end module having pre-fabricated connections for the association of other various equipment including: a heat exchanger, a distillation tower, and a reboiler. The modular amine plant capable of being installed at a site in less than about 5 days. The modular amine plant further having moment forces sufficient to withstand wind speeds of about 100 miles per hour.

Abstract: A method for removing acid gases from a fluid stream comprises a) treating the fluid stream in an absorption zone with an absorption medium which comprises an aqueous solution of at least one amine, conducting the treated fluid stream through at least two scrubbing zones and treating it with a non-acidic aqueous phase in order to transfer entrained amine and/or entrained amine decomposition products at least in part to the aqueous phase, wherein aqueous phase is recycled via at least one scrubbing zone and aqueous phase is conducted through at least one scrubbing zone without recycling. The method permits efficient retention of amines from the treated fluid streams.

Abstract: A method for collecting carbon dioxide from flue gas. The method includes: 1) mixing an aqueous solution of sodium carbonate with an amino alcohol activator to yield a CO2 absorbent; spraying the CO2 absorbent into the flue gas to produce a sodium bicarbonate slurry; 2) thermally decomposing the sodium bicarbonate slurry to produce a highly concentrated CO2 gas and an aqueous solution of sodium carbonate; 3) returning the aqueous solution of sodium carbonate to step 1) to form the CO2 absorbent for recycling; 4) cooling the highly concentrated CO2 gas for condensing hot water vapor therein; 5) carrying out gas-liquid separation on the highly concentrated CO2 gas, removing condensed water to yield highly purified CO2 gas; and 6) drying, compressing, and condensing the highly purified CO2 gas. An apparatus for collecting carbon dioxide from flue gas according to the method is also provided.

Abstract: A process for the removal of hydrogen sulfide from a gas stream in which the gas stream is first passed through a Claus unit operating at a sub-stoichiometric ratio (H2S:SO2) of greater than 2:1 to produce a tail gas stream comprising less than 2000 vppm SO2. This tail gas stream is then treated to increase the sulfur recovery to at least 99.5% by first directly cooling the tail gas stream by contact with water as a coolant, followed by contacting the gas stream with a circulating stream of a dilute, absorbent solution of a severely sterically hindered secondary aminoether alcohol to further cool the gas stream, and then removing the H2S from the stream using a stronger absorbent solution of a severely sterically hindered secondary aminoether alcohol.

Abstract: A process for removing acid gases from a fluid stream in which a) the fluid stream is treated with an absorption liquid which comprises at least one amine, a stripping aid, and water, wherein the stripping aid is selected from water-miscible liquids, the boiling temperature of which at atmospheric pressure is lower than that of water, b) the treated fluid stream is treated with a liquid aqueous phase in order to convert entrained stripping aid at least in part to the aqueous phase, c) the loaded aqueous phase is heated in order to expel the stripping aid at least in part, and d) the regenerated aqueous phase is cooled and at least in part recycled to step b). The stripping aid promotes the regeneration of the absorbent by stripping. Emissions of the stripping aid via the treated fluid stream are avoided by the treated fluid stream being scrubbed with a liquid aqueous phase.

Abstract: A method of deacidizing a gaseous effluent comprising acid compounds where the gaseous effluent is contacted in C1 with an adsorbent solution so as to obtain a gaseous effluent depleted in acid compounds and an absorbent solution laden with acid compounds, the absorbent solution being selected for its property of forming two separable phases when it has absorbed an amount of acid compounds and when it is heated. The absorbent solution laden with acid compounds is then heated in E1 and E3 so as to separate two fractions: a first absorbent solution fraction depleted in acid compounds and a second absorbent solution fraction enriched in acid compounds. These two fractions are then separated in BS1. The second fraction is regenerated in C2 so as to release part of the acid compounds, and the first absorbent solution fraction and the regenerated absorbent solution are recycled as absorbent solution.

Abstract: The present invention is directed to water-dispersible, oil-soluble triazine sulfide-scavenging compositions for use in hydrocarbon recovery and processing applications. The compositions include a triazine component, a glycol ether component, and an optional alcohol component. The compositions contain a minor amount of water up to a maximum of about 15% by volume. The compositions can be used in any type of sulfide-scavenging operation and significantly reduce corrosion problems found with conventional triazine scavengers.

Abstract: A multi-stage scrubbing system comprises a pre-scrubber system structured to receive a vent stream therein and pre-scrub the vent stream with a pre-scrubber fluid. The pre-scrubber system includes a first outlet for discharging a pre-scrubbed vent stream and a second outlet for discharging a discharge stream of pre-scrubber fluid. A main scrubber system is fluidly coupled to the first outlet of the pre-scrubber system for receiving and further scrubbing the pre-scrubbed vent stream.

Abstract: The absorptive removal of carbon dioxide from biogas using a scrubbing liquid in which carbon dioxide is chemically bound proceeds by heating the loaded scrubbing liquid, occurring after the absorption, to a temperature at which liberation of CO2 begins. Immediately thereafter, the loaded scrubbing liquid is fed to at least one centrifugal separator for separating off the gas phase from the liquid phase, wherein methane and dissolved fractions of CO2 escape via the gas phase. After separation is complete, the gas phase is passed into the absorber unit and the liquid phase is further heated to the temperature required for desorption and fed to the desorption unit for regeneration.

Abstract: An absorbent liquid according to the present invention is an absorbent liquid for absorbing CO2 or H2S or both from gas, in which the absorbent liquid includes an alkanolamine as a first compound component, and a second component including a nitrogen-containing compound having in a molecule thereof two members or more selected from a primary nitrogen, a secondary nitrogen, and a tertiary nitrogen or a nitrogen-containing compound having in a molecule thereof all of primary, secondary, and tertiary nitrogens. The absorbent liquid has an excellent absorption capacity performance and an excellent absorption reaction heat performance, as compared to an aqueous solution containing solely an alkanolamine and a nitrogen-containing compound in the same concentration in terms of wt %, and can recover CO2 or H2S or both from gas with smaller energy.

Abstract: Systems containing imidazoles or blends of imidazoles and amines are described herein. Methods of their preparation and use are also described herein. The methods of using the systems include the reduction of volatile compounds from gas streams and liquid streams.

Abstract: A method for recovering CO2 from gas to be processed containing CO2, includes bringing the gas to be processed containing CO2 and CO2 absorbent into contact with each other to absorb and remove CO2 from the gas to be processed; cleaning the treated gas from which CO2 has been removed with washing fluid at least once; heating the absorbent which has absorbed CO2, separating and removing CO2 gas from the absorbent and regenerating the absorbent; cooling the separated CO2 gas to condense moisture contained in the gas to obtain condensed water; and monitoring changes in concentration of the CO2 absorbent contained in the condensed water and depending on the value of the measured concentration, controlling supply of the condensed water so that the condensed water is reused as a part of the washing fluid or a part of the CO2 absorbent.

Abstract: An absorption medium for removing acid gases from a fluid stream comprises an aqueous solution (A) of an alkali metal salt of an N,N-di-C1-C4-alkylaminocarboxylic acid and (B) N-hydroxyethylpiperazine. The absorption medium has a low vapor pressure and an increased resistance to oxygen. Preferred fluid streams are combustion exhaust gases or biogas.

Abstract: A method of reducing sulfur compounds from an incoming gas stream, comprising flowing the gas stream over a hydrolysis catalyst to convert COS and CS2 to H2S and reduce SO2 to elemental sulfur to form an effluent stream; providing an acidic gas removal unit comprising an absorbent; flowing said effluent stream over said absorbent to produce a stream free of acidic gases; applying an acidic-gas desorption mode to said acidic-gas rich absorbent to produce an acidic gas stream; introducing oxygen to said acidic gas-rich stream; providing a direct oxidation vessel containing catalyst suitable for catalyzing the oxidation of the H2S to sulfur wherein the temperature of the vessel is at or above the sulfur dew point at the reaction pressure; and flowing said acidic gas-rich stream over said catalyst to produce a processed stream having a reduced level of sulfur compounds.

Abstract: The gaseous effluent to be treated is contacted in C1 with an absorbent solution selected for its property of forming two separable phases when it has absorbed an amount of acid compounds and when it is heated. According to the invention, the absorbent solution is regenerated in at least two stages in regeneration zones Z1 and Z2. At the end of the first regeneration stage in Z1, at least part of the partly regenerated absorbent solution is separated into two fractions in B1: a fraction rich in acid compounds and a fraction depleted in acid compounds. Fraction 10 rich in acid compounds is sent to the second regeneration stage in Z2. The fraction depleted in acid compounds and regenerated absorbent solution 6 from the second regeneration stage are recycled to absorption column C1. The method can be applied to combustion fumes decarbonation and to natural gas or synthesis gas deacidizing.

Abstract: A method for treating crude gas, in particular biogas, containing methane and carbon dioxide, in order to produce methane, and a plant suitable for carrying out the method. The method includes (a) washing the crude gas with an amine-containing washing solution, thereby forming a pure gas stream of methane and water, from which water is separated by subsequent cooling and condensation; (b) compressing and heating the washing solution containing CO2 and sulfur compounds and expanding the washing solution in a first expansion stage, during a secondary reaction time of 280 to 1200 seconds and at a constant reaction temperature; (c) cooling the purified washing solution and expanding it in a second expansion stage to normal pressure, whereupon any residual amounts of soluble CO2 and sulfur compounds are separated and the completely purified washing solution is cooled to normal temperature and returned to the washing stage.

Abstract: A process for the reduction of carbon dioxide and carbonyl sulfide from various types of gas emitting sources containing carbon dioxide and/or gas or liquid emitting sources containing carbonyl sulfide, using ion exchange resin.

Abstract: The present disclosure relates to a polymer material comprising mesopores extending between melamine-formaldehyde co-polymer nano-particles and wherein micropores extend within the co-polymer nano-particles, methods of producing the same and uses thereof.

Abstract: Provided are a CO2 absorber that reduces CO2 contained in flue gas; a regenerator that reduces CO2 contained in rich solvent absorbing CO2 to regenerate the rich solvent, so that lean solvent having the CO2 reduced in the regenerator is reused in the CO2 absorber; a heat exchanger that allows the rich solvent to exchange heat with the lean solvent; and a controller that controls to extract rich solvent portion that is part of the rich solvent, to allow the rich solvent portion to bypass the heat exchanger, and to be supplied into the top of the regenerator without exchanging heat so as to minimize a sum of an enthalpy that is taken out of the regenerator as CO2 gas accompanying steam and an enthalpy of the lean solvent after heat exchange with the rich solvent in the heat exchanger.

Abstract: The carbon dioxide contained in combustion fumes is absorbed by an aqueous amine solution in section B1. The decarbonated fumes are then washed with water in wash section B3. In order to prevent the discharge of amine degradation products with the decarbonated fumes, operation of the method is monitored and a fumes acid wash section U is used when required by the operating conditions of the carbon dioxide capture method.

Abstract: A method of using condensed water produced in a desulfurization apparatus includes the steps of: bringing a gas to be treated, containing a sulfur dioxide and a desulfurization absorption liquid, into contact with each other to absorb and eliminate the sulfur dioxide from the gas to be treated; cooling a desulfurized gas obtained by the elimination of the sulfur dioxide to produce condensed water from the desulfurized gas; and washing the desulfurization apparatus with the condensed water. In the step of washing the desulfurization apparatus, an inlet for introducing the gas to be treated into the desulfurization apparatus may be washed with the condensed water, and a mist eliminator for eliminating the desulfurization absorption liquid accompanying the desulfurized gas from the gas may be washed with the condensed water.

Abstract: A process for the capture of CO2 from gas streams comprising contacting a CO2 containing gas stream with an aqueous alkanolamine solution, wherein the alkanolamine is selected from the group consisting of: 3-piperidinemethanol, Tricine, 3-quinuclidinol, 3-piperidino-1,2-propanediol and their salts.

Abstract: Disclosed is a formulation for the absorption of CO2, which comprises water, at least one CO2 absorption compound and a carbonic anhydrase as an activator to enhance the absorption capacity of the CO2 absorption compound. The invention also concerns the use of carbonic anhydrase, in a CO2 absorption solution to increase the CO2 absorption rate of such solution.

Abstract: A premix is described for producing an absorption medium for removing acid gases from fluid streams. The premix comprises at least one alkanolamine, piperazine and water, the premix having a total amine content of more than 65% by weight, the molar ratio of water to piperazine in the premix being 1.6 to 4.8. The premix is characterized by a low solidification point. It is diluted with water and/or alkanolamine to give the ready-to-use absorption medium.

Abstract: A CO2 recovery system includes an absorber 2 and a regenerator 3. The absorber 2 includes a CO2 absorbing section 21 and a water-washing section 22. The CO2 absorbing section 21 allows flue gas 101 to come into contact with a basic amine compound absorbent 103 so that the basic amine compound absorbent 103 absorbs CO2 in the flue gas 101. The water-washing section 22 allows the decarbonated flue gas 101A in which the amount of CO2 has been reduced in the CO2 absorbing section 21 to come into contact with circulating wash water 104 and to be washed with the wash water 104 so that the amounts of the basic amine compounds entrained in the decarbonated flue gas 101A are reduced. The regenerator 3 releases CO2 from the basic amine compound absorbent 103 the CO2 absorbed therein.

Abstract: The present invention relates to a process for separating off CO2 from a gas stream, wherein in a second step the CO2 is removed from the CO2-absorbing agent by means of phase separation.

Abstract: This invention provides novel compositions comprising substituted polyamines as acid gas scrubbing solutions and methods of using the compositions in an industrial system. The invention relates to the use of such polyamine compounds in industrial processes to remove acidic contaminants from natural and industrial fluid streams, such as natural gas, combustion gas, natural gas, synthesis gas, biogas, and other industrial fluid streams. The compositions and methods of the invention are useful for removal, absorption, or sequestration of acidic contaminants and sulfide contaminants including CO2, H2S, RSH, CS2, COS, and SO2.

Abstract: A process for the selective absorption of normally gaseous acid components from hydrocarbon gas mixtures containing both the acidic components and gaseous non-acidic components which is carried out in a gas separation unit located at an offshore marine production installation. The sorbent used in the process comprises a severely sterically hindered amino ether. The process is capable of selectively removing H2S from gas mixtures which also contain CO2 in addition to the hydrocarbon components.

Abstract: Embodiments relate to methods and systems for loading a liquid solvent with a gas. Upon spraying the solvent into contact with the gas, droplets of the solvent absorb the gas and coalesce as a partial loaded solution. The solution then passes along at least one wetted wall column disposed in contact with the gas for further loading of the solvent. One exemplary application utilizes an amine as the solvent to be loaded with the gas, such as carbon dioxide.

Abstract: Apparatus and methods for recovering sulfur from acid gases. Acid gases containing relatively high amounts of carbonyl sulfide and/or one or more types of mercaptans can be treated in a sulfur recovery system employing an acid gas enrichment zone and a tail gas treatment zone, where partially-loaded sulfur absorbing solvent from the tail gas treatment zone is employed for sulfur absorption in the acid gas enrichment zone. Off-gas from the acid gas enrichment zone can be combined and hydrogenated with a sulfur recovery unit tail gas thereby increasing the total amount of sulfur recovery from the initial acid gas.

Abstract: A nanoclay based solid sorbent is provided having a nanoclay with at least one surface, and at least one amine containing compound wherein the amine containing compound is attached to the surface, as well as a method of making it. A method of capturing carbon dioxide gas is disclosed includes passing a gas from an effluent process stream containing carbon dioxide through the nanoclay based solid sorbent and capturing the carbon dioxide gas on the surface and within the nanoclay based solid sorbent. The nanoclay based solid sorbent having the captured carbon dioxide gas is regenerated by undergoing one or more cycles of desorption of the captured carbon dioxide gas from the nanoclay. The regenerated nanoclay based solid sorbent may then be reused.

Abstract: A system for carbon dioxide capture from flue gas and other industrial gas sources utilizes microcapsules with very thin polymer shells. The contents of the microcapsules can be liquids or mixtures of liquids and solids. The microcapsules are exposed to the flue gas and other industrial gas and take up carbon dioxide from the flue gas and other industrial gas and eventual precipitate solids in the capsule.

Abstract: Nanocomposite adsorbent materials and methods for their preparation and use are described. As an example, a polyaniline-graphite nanoplatelet nanocomposite may be used to adsorb carbon dioxide.

Abstract: An air pollution control system includes a desulfurization apparatus 13 that reduces sulfur oxide contained in flue gas 12 supplied from a boiler 11; and a CO2 recovery apparatus 15 including a CO2 absorber 21 that reduces CO2 contained in flue gas 12 that has been desulfurized by the desulfurization apparatus, with the aid of an amine absorbent and an absorbent regenerator 22 that regenerates the amine absorbent. Part 14a of desulfurized flue gas 14 containing SOx is supplied to treated flue gas 16, from which CO2 has been reduced and which is discharged from a top portion of the CO2 absorber 21, so that remaining mist amine accompanying the treated flue gas 16 is neutralized to amine sulfate or amine sulfite.