WO2021079609A1 - Co2 facilitated transport membrane, production method therefor, and co2 separation method and device - Google Patents

Abstract

Provided is a CO₂ facilitated transport membrane having improved CO₂ permeance and CO₂ permselectivity. The CO₂ facilitated transport membrane is formed so as to contain a CO₂ carrier and a particulate moisture absorption agent within a hydrophilic polymer gel membrane. More preferably, the moisture absorption agent is formed from porous particles and is present within the gel membrane in a dispersed manner. More preferably, the gel membrane is a hydrogel. More preferably, the gel membrane is supported by a hydrophilic porous membrane.

Description

CO2-promoted transport membrane and its manufacturing method, and CO2 separation method and equipment

The present invention relates to a CO _{2 promoted transport membrane used for separating carbon dioxide (CO 2 ), and more particularly to a CO 2} promoted transport membrane that separates carbon dioxide produced as a by-product in a hydrogen production process or the like at a high selective ratio with respect to hydrogen. also relates to processes for the manufacture of the CO ₂ -facilitated transport membrane, to CO ₂ separation method and device using the CO ₂ -facilitated transport membrane.

In the hydrogen production process, it is necessary to separate and remove _{CO 2} produced as a by-product in the hydrogen production process from the hydrogen gas.

Chemical absorption method used in the decarboxylation process large plants, such as existing hydrogen production plant and ammonia production plant requires regenerator giant CO ₂ absorption tower and CO ₂ absorbing solution in the separation of CO ₂ in the regeneration step the CO ₂ absorbing solution, since it requires a large amount of steam to remove CO ₂ from the heated absorption liquid for re-use liquid imbibed with CO _2, wasteful consumption of energy doing.

In recent years, as a measure against global warming, _{the spread of natural energy that does not emit CO 2} is expected, but since natural energy has a big cost problem, CO ₂ is separated from the exhaust gas of thermal power plants and steel mills. A method called CCS (Carbon dioxide Capture and Storage), which collects carbon dioxide and backfills it in the ground or the sea, is attracting attention. At present, it is assumed that the chemical absorption method will be applied to CCS as well, in which case not only a large-scale CO ₂ separation facility will be required _{to separate and recover CO 2 from the thermal power plant.} , It is necessary to put in a large amount of steam.

On the other hand, in the CO ₂ separation and recovery process using the membrane separation method, the separation is performed by the speed difference of the gas passing through the membrane using the pressure difference as the driving energy, and the pressure of the separated gas can be used as energy. In addition, it is expected as an energy-saving process because it does not involve phase change.

Gas separation membranes are roughly classified into organic membranes and inorganic membranes depending on the membrane material. Organic films have the advantages of being cheaper and more moldable than inorganic films. The organic membrane used for gas separation is generally a polymer membrane prepared by the phase conversion method, and the mechanism of separation is the solubility of gas in the membrane material and the diffusion rate of gas in the membrane. It is based on a dissolution / diffusion mechanism that separates gases due to differences.

The dissolution / diffusion mechanism is based on the idea that the gas first dissolves on the surface of the polymer membrane, and the dissolved molecules diffuse in the polymer chain gaps in the polymer membrane. The permeability coefficient _{P A} of gas components A, solubility coefficient _{S A,} when the diffusion coefficient is _{D A,} relational expression P _A = _S A × _D A is satisfied. Ideally separation factor alpha _{A / B,} for taking the ratio of the permeability coefficients of the components A and B, expressed as _{α A / B = P A /} P B, α A / B = (S A / S B ) _/ become _(D a / D _{B). Here,} S A / _{S B} solubility _selectivity, D A / _{D B} is called the diffusion selectivity.

The smaller the molecular diameter, the larger the diffusion coefficient, and in general, the contribution of diffusion selectivity is larger than the contribution of solubility selectivity in gas separation. Therefore, from a multi-component gas having a different molecular diameter to a gas having a small molecular diameter. It is difficult to suppress permeation and selectively permeate a gas having a large molecular diameter.

Therefore, it is extremely difficult to prepare a CO _{2 selective permeation membrane that separates CO 2 from a mixed gas containing H 2} and CO ₂ with high selectivity _{for H 2} having a small molecular diameter among gas molecules. It was difficult, and it was even more difficult to produce a _{CO 2} selective permeation membrane that functions at a high temperature of 100 ° C. or higher that can withstand practical use in a decarboxylation process such as a hydrogen production plant.

Therefore, a permeation membrane called a facilitative transport membrane, which uses a substance called a "carrier" that selectively and reversibly reacts with _{CO 2 and selectively permeates gas by a facilitative transport mechanism in addition to a dissolution / diffusion mechanism, has been studied.} (For example, see Patent Document 1 below). The accelerated transport mechanism has a structure in which a carrier that selectively reacts with _{CO 2 is contained in the membrane.} In such an accelerated transport membrane, _{in addition to physical permeation by the dissolution / diffusion mechanism, CO 2} also permeates as a reaction product with carriers, so that the permeation rate is promoted. On the other hand, since _{gases such as N 2} and H ₂ that do not react with carriers permeate only by the dissolution / diffusion mechanism, the CO ₂ separation coefficient for these gases is extremely large. Further, since the energy generated during the reaction between _{CO 2 and the carrier is used as the energy for the carrier to release CO 2} , it is not necessary to supply energy from the outside, which is essentially an energy saving process.

International Publication No. 2009/093666

In Patent Document 1, by using a specific alkali metal salt such as cesium carbonate or rubidium carbonate as a carrier, CO ₂ permeance and CO ₂ / H ₂ selectivity that can be practically used under high temperature conditions of 100 ° C. or higher are provided. A CO ₂ promoted transport membrane has been proposed.

_{The reaction between CO 2} and CO ₂ carriers by the accelerated transport mechanism is shown as the following (Chemical formula 1) as a general reaction formula. However, in (Chemical formula 1), it is assumed that the _{CO 2 carrier is a carbonate.} The symbol "⇔" in the reaction formula indicates that it is a reversible reaction.

(Chemical 1)
_{CO 2 + H 2 O + CO} 3 2- ⇔ 2HCO 3 -

Carbon dioxide is promoted and transported even when there is little water in the membrane, but since its permeation rate is generally low, it is necessary to retain a large amount of water in the membrane in order to obtain a high permeation rate. As is clear from (Chemical Formula 1) _{, the CO 2} permeance and CO ₂ selective permeability (for example, CO ₂ / H ₂ selectivity), which are performance indexes of _{the CO 2} promoted transport membrane, depend on the amount of water in the membrane. ..

Meanwhile, moisture in the film, by the differential pressure of the feed side and the permeate side of the CO ₂ and CO ₂ -facilitated transport membrane transmits CO ₂ -facilitated transport membrane, to flow to the permeate side. Therefore, if a sufficient amount of water in the film cannot be secured, the film performance will deteriorate. Further, the deterioration of the film performance tends to become more remarkable as the operating temperature exceeds 100 ° C. and becomes higher.

In view of the above-mentioned problems, an object of the present invention is to stably supply a CO ₂ promoted transport membrane having _{improved CO 2} permeance and CO _{2 selective permeability.}

In order to achieve the above object, the present invention provides _{a CO 2} promoting transport membrane _{characterized by containing a CO 2} carrier and a particulate hygroscopic agent in a gel membrane of a hydrophilic polymer.

Carbon dioxide is promoted and transported even when there is little water in the membrane, but since its permeation rate is generally low, it is necessary to retain a large amount of water in the membrane in order to obtain a high permeation rate. _{Therefore, according to the CO 2} promoting transport membrane having the above characteristics, since the gel membrane contains a particulate hygroscopic agent, the water retention capacity of the gel membrane is improved, and the CO ₂ permeance and the CO ₂ selective permeability are improved. There is expected.

Further, in the CO ₂ promoting transport membrane having the above characteristics, it is preferable that the hygroscopic agent is porous particles. As a result, the hygroscopic performance is improved by increasing the specific surface area of the hygroscopic agent, _{and further improvement in CO 2} permeance and CO ₂ selective permeability is expected.

Further, in the CO ₂ promoting transport membrane having the above characteristics, it is preferable that the hygroscopic agent is dispersed in the gel membrane. As a result, uniform improvement is expected over the entire surface of the CO _{2 promoted transport membrane having CO 2} permeance and CO _{2 selective permeability.}

Further, in the CO ₂ promoting transport membrane having the above characteristics, it is preferable that the particle size of the hygroscopic agent is 75 μm or less. Since _{it is assumed that the thickness of the gel film of the CO 2} promoting transport film is as thin as about 200 μm, if the particle size exceeds 75 μm, the film performance may deteriorate due to defects penetrating the gel film. The particle size is preferably suppressed to about 40% or less, more preferably about 35% or less, based on the thickness of the gel film.

Further, in the CO ₂ promoting transport membrane having the above characteristics, it is preferable that the hygroscopic agent is a silicon compound. Silica gel, zeolite and the like are assumed as silicon compounds that can be used as a hygroscopic agent.

Further, in the CO ₂ promoted transport film having the above characteristics, the hydrophilic polymer is selected from polyvinyl alcohol-polyacrylate copolymer, polyvinyl alcohol, polyacrylic acid, chitosan, polyvinylamine, polyallylamine, and polyvinylpyrrolidone. It is preferably a polymer to be used. Here, those skilled in the art may refer to the polyvinyl alcohol-polyacrylate copolymer as a polyvinyl alcohol-polyacrylic acid copolymer.

Further, in the CO ₂ promoting transport film having _{the above-mentioned characteristics, the CO 2} carrier contains at least one of an alkali metal carbonate, an alkali metal bicarbonate, an alkali metal hydroxide, and an amino acid. It is preferable that the alkali metal is composed of cesium or rubidium. Further, _{as an amino acid that can be used as a CO 2} carrier, for example, glycine, 2,3-diaminopropionate (DAPA) and the like are assumed.

Further, in the CO ₂ promoting transport membrane having the above characteristics, it is preferable that the gel membrane is a hydrogel.

Hydrogel is a three-dimensional network structure formed by cross-linking a hydrophilic polymer, and has the property of swelling by absorbing water.

In the CO ₂ promoting transport membrane having the above characteristics, by forming the gel membrane with a hydrogel having high water retention, the water retention capacity of the gel membrane is improved, _{and further improvement in CO 2} permeance and CO ₂ selective permeability is expected. Will be done.

Further, in the CO ₂ promoting transport membrane having the above characteristics, it is preferable that the gel membrane is supported on a hydrophilic porous membrane.

First, since the gel membrane is supported by the porous membrane, _{the strength of the CO 2} promoting transport membrane during use is improved. As a result, the pressure of the CO ₂ -facilitated transport membrane when applied to CO ₂ permeable membrane reactor (CO ₂ -facilitated transport membrane CO transformer having a), on both sides of the CO ₂ -facilitated transport membrane (reactor internal and external) Sufficient film strength can be secured even if the difference is large (for example, 2 atm or more).

Further, in general, when the porous membrane is hydrophobic, it is possible to prevent the moisture in the gel membrane from invading the pores in the porous membrane at 100 ° C. or lower and lower the membrane performance, and the gel at 100 ° C. or higher. Since the same effect can be expected even when the water content in the membrane is low, the use of a hydrophobic porous membrane is recommended, but the reason why the porous membrane that supports the gel membrane is hydrophilic will be described later. As a result, a gel film with few defects can be stably produced, and high selective permeability to hydrogen can be maintained.

Further, in the present invention, the CO ₂ promoted transport film having the above characteristics is used to supply a mixed gas containing a predetermined main component gas and CO _{2 to the CO 2} promoted transport film, and the CO ₂ promoted transport from the mixed gas. _{Provided is a CO 2} separation method characterized by separating the _{CO 2} that has permeated the membrane.

Furthermore, the present invention includes a CO ₂ -facilitated transport membrane having the above characteristics, supplying a mixed gas containing a predetermined main component gas and CO ₂ in the CO ₂ -facilitated transport membrane, the CO ₂ -facilitated transport membrane from the mixed gas _{Provided is a CO 2} separation apparatus characterized by separating the _{CO 2} that has passed through the gas.

Further, the present invention is a _{method for producing a CO 2} promoted transport film having the above-mentioned characteristics, wherein a step of preparing a sol solution composed of an aqueous solution containing the _{hydrophilic polymer, the CO 2 carrier, and the hygroscopic agent, and the above.} Provided is a method for producing _{a CO 2-} promoted transport film, which comprises a step of casting a sol solution into a hydrophilic porous film and then gelling to prepare the gel film.

According to the method for producing a CO ₂ promoted transport membrane having the above characteristics, when the sol solution is cast on the hydrophilic porous membrane in the step of producing the gel membrane, the pores of the porous membrane are filled with the sol solution, and further. , The sol solution is applied to the surface of the porous membrane. When a gel film is produced by gelling this sol solution, the gel film is filled not only on the surface of the porous film but also in the pores, so that defects are less likely to occur and the success rate of gel film formation is increased. ..

Considering the proportion of pores (permeance) and the fact that the pores are not straight and meandering (tortuosity) perpendicular to the film surface, the gel film in the pores has a large resistance to gas permeation. , The permeability is lower than that of the gel membrane on the surface of the porous membrane, and the gas permeance is lowered. On the other hand, when the cast solution is cast on the hydrophobic porous membrane, the inside of the pores of the porous membrane is not filled with the liquid, the cast solution is applied only to the surface of the porous membrane, and the pores are filled with gas. The gas permence in the upper gel layer is expected to be higher than that of the hydrophilic porous membrane.

However, as compared with the gel film in the pores, the gel film on the surface of the film is more likely to have minute defects, and the success rate of film formation is lowered. Here, assuming a case where _{CO 2} is separated from a mixed gas containing _{H 2} and CO _{2 , H 2} has a much smaller molecular size than _{CO 2} , so H ₂ is better _{than CO 2 at minute defects.} , Permeance is significantly increased. Except for the defective part, the CO ₂ permeance transmitted by the accelerated transport mechanism is much larger than _{the H 2} permeance transmitted by the physical dissolution and diffusion mechanism.

As a result, the hydrogen selectivity (CO ₂ / H ₂ ) when the hydrophobic porous membrane is used is lower than that when the hydrophilic porous membrane is used. Therefore, from the viewpoint of practical use, the _{stability and durability of the CO 2} promoted transport membrane are very important, and it is advantageous to use a hydrophilic porous membrane having high _{hydrogen selectivity (CO 2} / H _2). Become.

Further, in the _{method for producing a CO 2} promoted transport film having the above characteristics, in the step of preparing the sol solution, the hydrophilic polymer and the CO ₂ carrier are added to pure water to which the hygroscopic agent has been added first, and the mixture is stirred. It is preferable to do so. In the process of preparing the sol solution, by adding the hygroscopic agent to the pure water first, it is possible to adsorb the water molecules of the pure water to the hygroscopic agent without being affected _{by the CO 2 carriers added later.} It is possible to increase the water retention of the gel film.

According to the CO ₂ promoted transport membrane having the above characteristics and the method for producing the same, a CO ₂ promoted transport membrane having _{improved CO 2} permeance and CO ₂ selective permeability (for example, CO ₂ / H _{2 selectivity) is stably supplied.} be able to.

_{Further, according to the CO 2} separation method and apparatus having the above characteristics _{, CO 2} and H _{2 and the} like can be obtained by using _{a CO 2 promoting transport film having high CO 2} selective permeability (for example, CO ₂ / H ₂ selectivity). It is possible to selectively separate _{CO 2} from a mixed gas containing the main component gas of the above with high efficiency.

Sectional drawing which shows typically the structure in one Embodiment of the _{CO 2} promotion transport membrane which concerns on this invention. The process drawing which shows the manufacturing method of the _{CO 2} promotion transport membrane which concerns on this invention. The figure which lists the constituent conditions of the gel film of each sample of Examples 1 and 2 and Comparative Examples 1 and 2 used in the evaluation experiment of the membrane performance of the _{CO 2} promotion transport membrane which concerns on this invention _{FIG. 3 is a graph showing the film performance (CO 2} permeance, H ₂ permeance, CO ₂ / H ₂ selectivity) of sample S1 of Example 1 and sample C1 of Comparative Example 1 shown in FIG. _{FIG. 3 is a graph showing the CO 2} / H ₂ selectivity of samples S2 to S6 of Example 1 and sample C2 of Comparative Example 1 shown in FIG. _{The graph which shows the film performance (CO 2} permeance, H ₂ permeance, CO ₂ / H ₂ selectivity) of the sample G1 of Example 2 and the sample C3 of Comparative Example 2 shown in FIG. 3 in a graph. _{FIG. 3 is a graph showing the CO 2} / H ₂ selectivity of the samples G2 to G7 of Example 2 and the sample C2 of Comparative Example 1 shown in FIG. A block diagram schematically showing a schematic configuration in one embodiment of the _{CO 2} separation device according to the present invention.

The present inventor has by extensive studies, the gel film of occurrence of the reaction of CO ₂ and CO ₂ carrier shown in the above (Formula 1) containing CO ₂ carrier of CO ₂ facilitated transport membrane, free of particulate desiccant It was found that the CO ₂ permeance was improved with _{respect to the H 2 permeance, and the CO 2} / H ₂ selectivity was improved as compared with the _{conventional CO 2} promoting transport film containing no such hygroscopic agent. Then, based on the above new findings, the inventor of the present application has invented the CO ₂ promoting transport membrane shown below, a method for producing the same, and a CO ₂ separation method and apparatus.

[First Embodiment]
First, an embodiment of the CO ₂ promoted transport membrane and the method for producing the same (hereinafter, appropriately referred to as “the present accelerated transport membrane” and “the present production method”) according to the present invention will be described with reference to the drawings.

[Construction of this accelerated transport membrane]
_{This accelerated transport membrane contains a CO 2} carrier and a particulate hygroscopic agent in a gel membrane of a hydrophilic polymer containing water _{, and has high CO 2} permeation and CO ₂ selective permeability (for example, CO ₂ / H ₂ selectivity). a CO ₂ facilitated transport membrane having a applicable a CO ₂ -facilitated transport membrane to CO ₂ permeable membrane reactor, and the like. Further, in this accelerated transport membrane, a hydrophilic porous membrane is adopted as a support membrane for supporting the gel membrane in order to stably realize _{high CO 2 selective permeability.}

Specifically, this accelerated transport film is, for example, a polyvinyl alcohol-polyacrylic acid (PVA / PAA) salt copolymer, polyvinyl alcohol, polyacrylic acid, chitosan as a hydrophilic polymer which is a film material of a gel film. , Polyvinylamine, polyallylamine, or polyvinylpyrrolidone, and as CO ₂ carriers, carbonates of alkali metals such as cesium carbonate (Cs ₂ CO ₃ ), rubidium carbonate (Rb ₂ CO ₃ ), or bicarbonate, or , Hydrophilic or amino acids such as glycine and 2,3-diaminopropionate (DAPA) are used, and porous particles such as silica gel and graphite are used as the particulate hygroscopic agent. When graphite particles are used as the particulate hygroscopic agent, the graphite surface is modified with a surfactant to reduce water repellency by the method described later.

Here, when the CO ₂ carrier is an alkali metal carbonate, the reaction shown in (Chemical formula 1) above occurs, but when the CO ₂ carrier is an alkali metal hydroxide, the following (Chemical formula 2) occurs. The reaction shown is occurring. In (Chemical Formula 2), the case where the alkali metal is cesium is shown as an example.

(Chemical 2)
CO ₂ + CsOH → CsHCO ₃
CsHCO ₃ + CsOH → Cs ₂ CO ₃ + H ₂ O

The above (Chemical formula 2) can be summarized as shown below (Chemical formula 3). That is, this indicates that the added cesium hydroxide is converted to cesium carbonate. Furthermore, from the above (Chemical formula 2), it can be seen that the same effect can be obtained even when a bicarbonate is added instead of the alkali metal carbonate as _{the CO 2 carrier.}

(Chemical 3)
CO ₂ + 2CsOH → Cs ₂ CO ₃ + H ₂ O

When using amino acids such as glycine or DAPA as CO ₂ carrier, carbon dioxide does not react with _NH ^{3 +,} are known to react with free NH ₂ in. Therefore, when using amino acids such as glycine or DAPA as CO ₂ carrier, with the addition of the number of moles or more alkali to the amino acid, the NH ₃ ⁺ dissolved in the sol solution described later deprotonated NH ₂ Need to be converted to. As the alkali, it deprives proton from NH ₃ ⁺ protonated, as long as it has only strongly basic can be converted into NH _2, can be suitably used a hydroxide or carbonate of an alkali metal element.

As an example, the particulate hygroscopic agent used is one in which the particle size is classified to 75 μm or less by sieving. The reason for classifying the particle size to 75 μm or less is that the film thickness of the gel film is assumed to be about 200 μm to 300 μm. Therefore, when the particle size exceeds 75 μm, a path penetrating the gel film via the hygroscopic agent is created. This is because there is a high possibility that it will be formed as a defect, and there _{is a concern that the film performance, particularly the CO 2} selective permeability, will be deteriorated.

Further, as an example, this accelerated transport membrane is composed of a hydrophilic porous membrane 2 carrying a gel membrane 1 and a three-layer structure supported by a hydrophobic porous membrane 3, as schematically shown in FIG. .. Further, the hydrophilic porous membrane 2 supporting the gel film 1 may have a four-layer structure sandwiched between two hydrophobic porous membranes 3. Since the gel film 1 is supported by the hydrophilic porous film 2 and has a certain mechanical strength, it does not necessarily have to have a structure supported or sandwiched by the hydrophobic porous film 3. For example, the mechanical strength can be enhanced by forming the hydrophilic porous membrane 2 in a cylindrical shape. Therefore, the accelerated transport membrane is not necessarily limited to a flat plate.

Further, based on the total weight of the hydrophilic polymer and the CO ₂ carrier in the gel film, the hydrophilic polymer is present in the gel film in the range of about 10 to 80% by weight, and the CO ₂ carrier is about 20 to 90% by weight. It exists in the range of%.

Further, the particulate hygroscopic agent is, for example, about 0.01 to 0.2% by weight, more preferably about 0.01 to 0.1% by weight, based on the total weight of the sol solution excluding the hygroscopic agent described later. % Is present in the gel membrane. Further, based on the total weight of the hydrophilic polymer and the CO ₂ carrier, about 0.12 to 2.4% by weight, more preferably about 0.12 to 1.2% by weight is present. Further, based on the weight of the hydrophilic polymer, there are about 0.44 to 8.8% by weight, more preferably about 0.44 to 4.4% by weight.

In addition to hydrophilicity, the hydrophilic porous membrane preferably has heat resistance of 100 ° C. or higher, mechanical strength, and adhesion to the gel membrane, and further has a porosity (porosity) of 55% or higher and is fine. The pore diameter is preferably in the range of 0.1 to 1 μm. In the present embodiment, a hydrophilic tetrafluoroethylene polymer (PTFE) porous membrane is used as the hydrophilic porous membrane satisfying these conditions.

In addition to hydrophobicity, the hydrophobic porous membrane preferably has heat resistance of 100 ° C. or higher, mechanical strength, and adhesion to the gel membrane, and further has a porosity (porosity) of 55% or higher and is fine. The pore diameter is preferably in the range of 0.1 to 1 μm. In the present embodiment, a non-hydrophilic ethylene tetrafluoroethylene polymer (PTFE) porous membrane is used as the hydrophobic porous membrane satisfying these conditions.

[Manufacturing method of this accelerated transport membrane]
Next, an embodiment of the method for producing the accelerated transport membrane (the present production method) will be described with reference to FIG. In the following description, it is assumed that PVA / PAA salt copolymer is used as the hydrophilic polymer, cesium carbonate (Cs ₂ CO _{3 ) is used as the CO 2} carrier, and silica gel or graphite having a particle size of 75 μm or less is used as the particulate hygroscopic agent. .. When graphite is used as the particulate hygroscopic agent, the surface of graphite is modified with a surfactant by a method described later to reduce water repellency. The addition amounts of the hydrophilic polymer, the CO ₂ carrier, and the hygroscopic agent are examples, and the addition amounts used in the sample preparation of Examples 1 and 2 below are exemplified.

First, a sol solution composed of an aqueous solution containing a PVA / PAA salt copolymer, a CO ₂ carrier, and a particulate hygroscopic agent is prepared (step 1). More specifically, 50 g of pure water and a predetermined amount of hygroscopic agent are added to a container (for example, a weighing bottle) and stirred to adsorb water molecules of pure water to the hygroscopic agent, and then a PVA / PAA salt copolymer. Add 1.25 g (tentative name SS gel manufactured by Sumitomo Seika), 3.44 g of cesium carbonate, and pure water to which a hygroscopic agent has been added first, and stir until it dissolves (about 24 hours) to make a sol solution. To get. In the present embodiment, the amount of the hygroscopic agent added was adjusted within the range of 0.01 to 0.2% by weight with respect to the total weight of the sol solution excluding the hygroscopic agent.

In the present embodiment, when graphite is used as a hygroscopic agent, the surface of graphite is surface-modified with a surfactant in advance to reduce water repellency in the following manner. As an example, the surface modification treatment is carried out by adding graphite particles to a mixture of 30 g of pure water and 0.3 g of a surfactant and stirring with a stirrer for 24 hours. In the present embodiment, the nonionic surfactant acetylenol E00 is used as the surfactant, but if it is possible to surface-modify graphite as the surfactant to reduce water repellency, the nonionic surfactant is used. It is not limited to the agent, and even a nonionic surfactant is not limited to acetylenol E00.

As a post-step of step 1, 0.125 g of water-soluble nylon may be added to the sol solution obtained in step 1 and stirred at 80 ° C. for 24 hours.

Next, the sol solution obtained in step 1 or the post-step of step 1 is subjected to a hydrophilic PTFE porous membrane (for example, manufactured by Sumitomo Electric Fine Polymer, WPW-020-80, film thickness 80 μm, pore diameter 0.2 μm, void ratio). Approximately 75%) and hydrophobic PTFE porous membrane (for example, manufactured by Sumitomo Electric Fine Polymer, Fluoropore FP010, film thickness 60 μm, pore diameter 0.1 μm, void ratio about 55%) Cast with an applicator on the surface of the PTFE porous membrane side (step 2). The cast thickness of the samples of Examples and Comparative Examples described later is 500 μm. Here, the sol solution permeates into the pores in the hydrophilic PTFE porous membrane, but the permeation stops at the interface of the hydrophobic PTFE porous membrane, and the sol solution does not permeate to the opposite surface of the layered porous membrane. There is no sol solution on the side surface of the hydrophobic PTFE porous membrane of the layered porous membrane, which facilitates handling.

Next, the hydrophilic PTFE porous membrane after casting is naturally dried at room temperature, and then the sol solution is gelled to form a gel membrane (step 3). Here, gelation means that a sol solution, which is a dispersion liquid of a polymer, is dried to form a solid state, and a gel film is a solid film produced by the gelation, and is a liquid film. Clearly distinguished.

In this production method, since the sol solution is cast on the surface of the layered porous membrane on the hydrophilic PTFE porous membrane side in step 2, the gel film is formed on the surface (cast surface) of the hydrophilic PTFE porous membrane in step 3. Since it is formed by filling the pores as well as being formed, defects (micro defects such as pinholes) are less likely to occur, and the success rate of gel film formation is increased. In step 3, it is desirable that the naturally dried PTFE porous membrane is further thermally crosslinked at a temperature of about 120 ° C. for about 2 hours. In the samples of Examples and Comparative Examples described later, thermal cross-linking is performed. By thermal cross-linking, the film thickness of the gel film becomes about 200 μm.

As described above, through the steps 1 to 3, as schematically shown in FIG. 1, the hydrophilic porous membrane 2 carrying the gel film 1 is supported by the hydrophobic porous membrane 3, and this accelerated transport membrane has a three-layer structure. To get. Continuing from step 3, the same hydrophobic PTFE porous membrane as the hydrophobic PTFE porous membrane of the layered porous membrane used in step 2 was overlaid on the gel layer side of the surface of the hydrophilic PTFE porous membrane obtained in step 3, and the gel film was formed. The main accelerated transport membrane having a four-layer structure in which the hydrophilic porous membrane 2 carrying 1 is sandwiched between two hydrophobic porous membranes 3 may be obtained. In FIG. 1, the state in which the gel film 1 is filled in the pores of the hydrophilic PTFE porous film 2 is schematically shown linearly.

[Evaluation of membrane performance of this accelerated transport membrane]
Hereinafter, regarding the specific membrane performance of this accelerated transport film, the samples S1 to S6 of Example 1 in which silica gel particles are added as a particulate hygroscopic agent in the gel film, and the surface activity as a particulate hygroscopic agent in the gel film. Samples G1 to G7 of Example 2 to which silica gel particles surface-modified with an agent were added, samples C1 to C2 of Comparative Example 1 to which no particulate hygroscopic agent was added to the gel film, and The result of evaluation using the sample C3 of Comparative Example 2 in which graphite particles which have not been surface-modified as a particulate hygroscopic agent are added to the gel film will be described.

The samples S1 to S6 and G1 to G7 are produced through the steps 1 (including the post-step) to 3 of the above-mentioned manufacturing method, and the samples C1 to C2 have a hygroscopic agent in the sol solution in the step 1. It was prepared in the same manner as the samples S1 to S6 and G1 to G7 except that it was not added, and the sample C3 was subjected to a surface modification treatment with a surfactant on the graphite particles added in step 1. It is prepared in the same manner as the samples G1 to G7 except that the sample G1 to G7 is not used. Therefore, the amount of the PVA / PAA salt copolymer and cesium carbonate added is the same between the samples of Example 1, Example 2, Comparative Example 1, and Comparative Example 2, and the amount of the particulate hygroscopic agent is the same. Except for differences in the amount added or the presence or absence of surface modification treatment on graphite particles
There is no difference in manufacturing conditions.

As shown in FIG. 3, the addition amounts of the silica gel particles of the samples S1 to S6 of Example 1 were, in order, 0.08% by weight and 0.01% by weight with respect to the total weight of the sol solution excluding the hygroscopic agent. , 0.02% by weight, 0.05% by weight, 0.08% by weight, and 0.1% by weight.

As shown in FIG. 3, the amount of the surface-modified graphite particles added to the samples G1 to G7 of Example 2 was, in order, 0.01% by weight based on the total weight of the sol solution excluding the hygroscopic agent. , 0.01% by weight, 0.04% by weight, 0.05% by weight, 0.08% by weight, 0.1% by weight, 0.2% by weight.

As shown in FIG. 3, the amount of the particulate hygroscopic agents (silica gel particles, graphite particles) added to the samples C1 to C2 of Comparative Example 1 was 0, and the surface-modified untreated graphite of Sample C3 of Comparative Example 2 was added. The amount of particles added is set to 0.01% by weight with respect to the total weight of the sol solution excluding the hygroscopic agent.

Next, an experimental method for evaluating the film performance of each sample of Examples 1 and 2 and Comparative Examples 1 and 2 will be described.

Each sample was used by fixing a fluororubber gasket as a sealing material between the supply side chamber and the permeation side chamber of the stainless steel flow-type gas permeation cell. The experimental conditions are common to each sample, and the flow-type gas permeation cell is installed in a constant temperature bath (electric furnace), and the temperature in the cell is fixed at 160 ° C. The relative humidity in the cell is 80%.

The supply-side gas supplied to the supply-side chamber is a _{mixed gas consisting of CO 2} , H ₂ , and H _{2 O (steam). Specifically, CO 2} and H ₂ are supplied at a flow rate of 100 ml / min, respectively. was allowed to merge, it is produced by mixing and H _{2 O} (steam) by passing the bubbler (humidifier). The supply side pressure is 445 kPa (G). In addition, (G) means gauge pressure. On the other hand, the pressure in the permeation concubine is atmospheric pressure. The pressures in the supply side chamber and the permeation side chamber are adjusted by providing a back pressure regulator on the downstream side of the cooling trap in the middle of the exhaust gas discharge path.

The gas that has permeated the accelerated transport membrane of each sample is collected in a container after passing through a cooling trap from the permeation side chamber side, and is quantified by a gas chromatograph. The amount of gas that has passed through the accelerated transport membrane of each sample is small, and _{in order to match the CO 2 concentration within the measurement range of the gas chromatograph, N 2 is} used as a dilution gas in the container at a flow rate of 100 ml / min. To supply. _{The permeance of CO 2} and H ₂ [mol / (m ² · s · kPa)] is calculated from the result quantified by the gas chromatograph and the flow rate of _{N 2 , and the CO 2} / H ₂ selectivity is calculated from the ratio.

Next, the performance of each sample film of Examples 1 and 2 and Comparative Examples 1 and 2 obtained in the above experimental results is compared. 3, Examples 1, 2 and structure condition (CO ₂ carrier gel films of the samples of Comparative Examples 1 and 2, CO ₂ hydration reaction catalyst, CO ₂ carrier and CO ₂ hydration molar ratio of catalyst, Hydrophilic polymer) and membrane performance (CO ₂ permence, H ₂ permence, CO ₂ / H ₂ selectivity) are listed.

_{First, the film performance (CO 2} permeance, H ₂ permeance, CO ₂ / H ₂ selectivity) of sample S1 of Example 1 and sample C1 of Comparative Example 1 is compared. Here, the effect of the presence or absence of particulate hygroscopic agents (silica gel particles) in the gel film on the film performance is evaluated. FIG. 4 (A) shows the CO ₂ permeance and the H ₂ permeance of the samples S1 and C1 as a graph, and FIG. 4 (B) shows the CO ₂ / H ₂ selectivity of the samples S1 and C1 as a graph. The black circles (●) and white circles (○) in FIG. 4 (A) _{indicate the CO 2} permeances of sample S1 and sample C1, respectively, and the black squares (■) and white squares (□) indicate H _{2 of samples S1 and sample C1.} The permeances are shown respectively, and the black triangles (▲) and white triangles (Δ) in FIG. 4 (B) show the CO ₂ / H ₂ selectivity of the samples S1 and C1, respectively. The horizontal axes of FIGS. 4 (A) and 4 (B) indicate the elapsed time from the start of the experiment.

From FIG. 4, _{H 2} permeance of samples S1, when compared with _{H 2} permeance of sample C1, with respect to substantially the same or slightly larger, CO ₂ permeance of samples S1 is different from the CO ₂ permeance of Sample C1 After 1 hour, the elapsed time increased 1.6 times or more, and the addition of silica gel particles to the gel film _{increased the CO 2} permeance compared to the case without addition, resulting in CO ₂ / H. ₂ It can be seen that the selectivity is greatly improved. Further, the CO ₂ / H ₂ selectivity of the sample S1 does not change significantly with the passage of time, whereas the CO ₂ / H ₂ selectivity of the sample C1 tends to decrease with the passage of time.

_{Next, the CO 2} / H ₂ selectivity of Samples S2 to S6 of Example 1 in which the amount of silica gel particles added is different and the CO 2 / H 2 selectivity of Sample C2 of Comparative Example 1 in which the particulate hygroscopic agent is not added to the gel film is compared. Do. Here, the effect of the amount of the particulate hygroscopic agent (silica gel particles) added in the gel film on the CO ₂ / H _{2 selectivity is evaluated.} FIG. 5 is a graph showing _{the CO 2} / H ₂ selectivity of samples S2 to S6 and C2 after 1 hour. The horizontal axis of FIG. 5 shows the amount of silica gel particles added (% by weight based on the total weight of the sol solution excluding the hygroscopic agent).

From FIG. 5, in Example 1 in which the silica gel particles were added into the gel film, when the addition amount of the silica gel particles was in the range of 0.01% by weight to 0.1% by weight, the addition amount of the silica gel particles increased. , CO ₂ / H ₂ selectivity tends to increase gradually.

Here, it is considered that the water molecules adsorbed on the surface of the silica gel particles in steps 1 and 2 are formed on the surface of the gel film through the drying process of step 3. As a result, the water molecules newly infiltrated into the gel film enter the microspace in the silica gel particles, so that the CO ₂ promoted transport reaction shown in (Chemical Formula 1) above is promoted.

_{Next, the film performance (CO 2} permeance, H ₂ permeance, CO ₂ / H ₂ selectivity) of sample G1 of Example 2 and sample C3 of Comparative Example 2 is compared. Here, the influence of the presence or absence of surface modification treatment by the surfactant of the particulate hygroscopic agent (graphite particles) in the gel film on the film performance is evaluated. FIG. 6 (A) shows the CO ₂ permeance and the H ₂ permeance of the samples G1 and C3 as a graph, and FIG. 6 (B) shows the CO ₂ / H ₂ selectivity of the samples G1 and C3 as a graph. The black circles (●) and white circles (○) in FIG. 6 (A) _{indicate the CO 2} permeances of sample G1 and sample C3, respectively, and the black squares (■) and white squares (□) indicate H _{2 of samples G1 and sample C3, respectively.} The permeances are shown respectively, and the black triangles (▲) and white triangles (Δ) in FIG. 6 (B) show the CO ₂ / H ₂ selectivity of the samples G1 and C3, respectively. The horizontal axes of FIGS. 6 (A) and 6 (B) indicate the elapsed time from the start of the experiment.

From FIG. 6, _{H 2} permeance of samples G1 when compared with _{H 2} permeance of samples C3, against going slightly larger over time, CO ₂ permeance of samples G1 is CO ₂ samples C3 permeance Compared with, the elapsed time increased significantly from 1 hour to 1.5 hours by about 1.6 to 4.4 times, and after the elapsed time was 1 hour or later, the surface of the gel film with a surfactant was applied. _{By adding the modified graphite particles, the CO 2} permeance is increased as compared with the case where the surface is not modified, and as a _{result, the CO 2} / H ₂ selectivity is greatly improved. I understand. Further, the CO ₂ permeance of the sample G1 does not change significantly with the passage of time, whereas the CO ₂ permeance of the sample C3 tends to decrease significantly with the passage of time. Further, the CO ₂ / H ₂ selectivity of the sample G1 did not change significantly with the passage of time, and further, a high value of about 350 to 400 could be maintained at a temperature of 160 ° C.

It is considered that this is because the water-repellent graphite particles that have not been surface-modified cannot sufficiently adsorb water molecules in the pores of the graphite particles and cannot sufficiently maintain the water retention of the gel film. Regarding the film performance of Sample C3 of No. 2, Comparative Example 1 in which no particulate hygroscopic agent was added to the gel film, except for individual differences of the samples and the possibility of pinholes occurring due to the graphite particles exhibiting water repellency. It is shown that there is basically no big difference from the film performance of the sample C1 of the above.

Next, the samples G2 to G7 of Example 2 in which the amounts of the graphite particles subjected to the surface modification treatment with the surfactant are different, and the sample of Comparative Example 1 in which the particulate hygroscopic agent is not added to the gel film. The CO ₂ / H ₂ selectivity of C2 is compared. Here, the effect of the amount of the particulate hygroscopic agent (graphite particles subjected to the surface modification treatment) added in the gel film on the CO ₂ / H _{2 selectivity is evaluated.} FIG. 7 is a graph showing _{the CO 2} / H ₂ selectivity of the samples G2 to G7 and C2 after 1 hour. The horizontal axis of FIG. 7 shows the amount of the surface-modified graphite particles added (% by weight based on the total weight of the sol solution excluding the hygroscopic agent).

From FIG. 7, in Example 2 in which the graphite particles subjected to the surface modification treatment were added to the gel film, CO was added in the range of 0.01% by weight to 0.04% by weight of the graphite particles. It can be seen that there is a maximum value of ₂ / H _{2 selectivity.} In the accelerated transport film of Example 2, when the addition amount of graphite particles increased by more than 0.04% by weight, the CO ₂ / H ₂ selectivity tended to decrease, and the same as in Example 1 in which silica gel particles were added. By comparison, the effect is exhibited even when the amount of the particulate hygroscopic agent added is small.

[Second Embodiment]
_{Next, the CO 2} separation apparatus and the CO _{2 separation method to which the CO 2} promotion transport membrane described in the first embodiment is applied will be described with reference to FIG. Note that in the CO ₂ separation device and CO ₂ separation process, the raw material gas to be CO ₂ separation, the predetermined _N 2, _{H 2} or the like which does not transmit only a lysis-diffusion mechanism of CO ₂ and CO ₂ -facilitated transport membrane A mixed gas containing the main component gas of is assumed.

FIG. 8 is a cross-sectional view schematically showing a schematic structure of _{the CO 2 separation device 10 of the present embodiment.} In the present embodiment, as an example, rather than CO ₂ -facilitated transport membrane of the plate type structures described in the first embodiment, using a CO ₂ facilitated transport membrane which is deformed into a cylindrical structure. FIG. 8 (a) _{shows a cross-sectional structure in a cross section perpendicular to the axis of the CO 2} promoted transport membrane (this accelerated transport membrane) 11 having a cylindrical structure, and FIG. 8 (b) shows the axis of the main promoted transport membrane 11. The cross-sectional structure in the cross section passing through the center is shown.

The accelerated transport film 11 shown in FIG. 8 has a structure in which a gel film 1 is supported on an outer peripheral surface of a cylindrical hydrophilic ceramic porous film 2. As the gel film 1, the polyvinyl alcohol-polyacrylic acid (PVA / PAA) salt copolymer is used as an example of the film material of the gel film as in the first embodiment, and the gel film 1 is used as a CO ₂ carrier. Using alkali metal carbonates such as cesium carbonate (Cs ₂ CO ₃ ) and rubidium carbonate (Rb ₂ CO ₃ ), surface modification treatment with silica gel particles and surfactant was performed as a particulate hygroscopic agent. Use graphite particles. Since the method for producing the gel film 1 and the film performance of the second embodiment are basically the same as those of the first embodiment, redundant description will be omitted.

As shown in FIG. 8, the cylindrical main accelerated transport membrane 11 is housed in a bottomed cylindrical container 12, a supply side space 13 surrounded by an inner wall of the container 12 and a gel film 1, and a ceramic porous membrane. A transmissive side space 14 surrounded by the inner wall of No. 2 is formed. On one side of the bottoms 12a and 12b on both sides of the container 12, a first inlet 15 for feeding the raw material gas FG into the supply side space 13 and a sweep gas SG
_{A second inlet 16 is provided to feed the CO 2} into the permeation side space 14, and the raw material gas EG after CO 2 is separated is discharged from the supply side space 13 on the other side of the bottoms 12a and 12b on both sides of the container 12. A first exhaust port 17 is provided, and a second exhaust port 18 is provided to discharge the exhaust gas SG', which is a mixture of the permeated gas PG containing _{CO 2} that has permeated the accelerated transport film 11 and the sweep gas SG, from the permeation side space 14. Has been done. The container 12 is made of stainless steel, for example, and is not shown, but has been described in the first embodiment as an example between both ends of the accelerated transport film 11 and the inner walls of the bottoms 12a and 12b on both sides of the container 12. Similar to the experimental device, the fluororubber gasket is interposed as a sealing material to fix the accelerated transport film 11 in the container 12. The method for fixing and sealing the accelerated transport membrane 11 is not limited to the above method.

In addition, in FIG. 8 (b), the first inlet 15 and the first outlet 17 are provided one by one in the supply side space 13 which is separated into left and right in FIG. 8 (b). However, as shown in FIG. 8A, the supply side space 13 communicates in an annular shape, so that the first inlet 15 and the first discharge port 17 are connected to either the left or right supply side space 13. It may be provided. Further, in FIG. 8B, a first inlet 15 and a second inlet 16 are provided on one side of the bottoms 12a and 12b, and a first outlet 17 and a second outlet are provided on the other side of the bottoms 12a and 12b. Although the configuration in which the outlet 18 is provided is illustrated, the first inlet 15 and the second discharge port 18 are provided on one side of the bottoms 12a and 12b, and the first discharge port 17 and the second discharge port 17 and the second are provided on the other side of the bottoms 12a and 12b. The inlet 16 may be provided. That is, the flow directions of the raw material gases FG and EG and the flow directions of the sweep gas SG and the exhaust gas SG'may be reversed.

In the CO ₂ separation method of the second embodiment, the raw material gas FG is fed into the supply side space 13 to supply the raw material gas FG to the supply side surface of the promotion transport membrane 11, and is included in the gel film 1 of the promotion transport membrane 11. The CO ₂ carrier is reacted with _{CO 2} in the raw material gas FG _{to selectively permeate CO 2} with a high selectivity for the main component gas, and the raw material gas EG with an increased concentration of the main component gas after _{CO 2 separation is supplied.} It is discharged from the side space 13.

The reaction between CO ₂ and CO _{2 carriers requires the supply of water (H 2} O) as shown in the reaction formula of (Chemical Formula 1) above, and the more water contained in the gel film 1, the more the chemical equilibrium. Is shifted to the product side (right side), and it can be seen that the permeation of _{CO 2 is promoted.} When the temperature of the raw material gas FG is as high as 100 ° C. or higher, the gel film 1 in contact with the raw material gas FG is also exposed to a high temperature of 100 ° C. or higher, so that the water contained in the gel film 1 evaporates. Since it penetrates into the transmission side space 14 like _{CO 2, it is necessary to supply steam (H 2} O) to the supply side space 13. The steam may be contained in the raw material gas FG, or may be supplied to the supply side space 13 separately from the raw material gas FG. In the latter case, the transmitted Steam (H 2 _O) was separated from the exhaust gas SG 'to the permeate side space 14 may be circulated to the feed-side space 13.

_{In the CO 2} separation device shown in FIG. 8, a configuration example in which the supply side space 13 is formed on the outside of the cylindrical main promotion transport film 11 and the transmission side space 14 is formed on the inside has been described, but the supply side space is inside. 13 may be formed, and the transmission side space 14 may be formed on the outside. Further, the accelerated transport film 11 may have a structure in which the gel film 1 is supported on the inner peripheral surface of the cylindrical hydrophilic ceramic porous film 2. Further, the _{accelerated transport membrane 11 used in the CO 2} separation device is not limited to a cylindrical shape, but may be a cylindrical shape having a cross-sectional shape other than a circular shape, and further has a flat plate type structure as shown in FIG. This accelerated transport membrane may be used.

_{Next, as an application example of the CO 2} separation device described in the present embodiment, _{a CO transformer (CO 2} permeation type membrane reactor) provided with the accelerated transport membrane will be briefly described.

For example, when the CO _{2 permeation type membrane reactor is constructed by using the CO 2} separation device 10 shown in FIG. 8, the supply side space 13 is filled with a CO transformation catalyst, and the supply side space 13 is used as a CO transformer. Can be done.

The CO ₂ permeation type membrane reactor receives, for example, _{a raw material gas FG containing H 2} as a main component generated by a steam reformer into a supply side space 13 filled with a CO transformation catalyst and is contained in the raw material gas FG. This is an apparatus for removing carbon monoxide (CO) by the CO transformation reaction shown in (Chemical Formula 4) below. _{Then, the CO 2} produced by the CO transformation reaction is selectively permeated through the permeation side space 14 by the accelerated transport film 11 to be removed, thereby shifting the chemical equilibrium of the CO transformation reaction to the hydrogen generation side. _{It is possible to remove CO and CO 2} at a high conversion rate at the same reaction temperature beyond the limit due to equilibrium restrictions. Then, the raw material gas EG mainly of _{H 2} after removal of CO and CO ₂ are removed from the feed-side space 13.

(Chemical 4)
CO + H ₂ O ⇔ CO ₂ + H ₂

Since the performance of the CO transformation catalyst subjected to the CO transformation reaction tends to decrease with temperature, the operating temperature is considered to be at least 100 ° C., and the supply of the raw material gas FG supplied to the supply side surface of the accelerated transport membrane 11 The temperature is 100 ° C. or higher. Therefore, the raw material gas FG is adjusted to a temperature suitable for the catalytic activity of the CO transformation catalyst, and then sent into the supply side space 13 filled with the CO transformation catalyst, and the CO transformation reaction in the supply side space 13 ( It is supplied to the accelerated transport film 11 via an exothermic reaction).

On the other hand, the sweep gas SG _{lowers the partial pressure of the permeated gas PG containing CO 2} that has permeated the facilitating transport film 11, maintains the permeation propulsive force of the facilitating transport film 11, and discharges the permeated gas PG to the outside. Used to do. However, when the partial pressure of the raw material gas FG is sufficiently high, it is not necessary to flow the sweep gas SG because the partial pressure difference that becomes the permeation propulsion force can be obtained without flowing the sweep gas SG. Further, as the gas species used in the sweep gas SG, in the same manner as in the evaluation experiments of the membrane performance of the first embodiment, can also use the steam (H 2 _O), also further, Ar or the like inert gas used The sweep gas SG is not limited to a specific gas type.

[Another Embodiment]
Hereinafter, another embodiment will be described.

<1> In Examples 1 and 2 of the first embodiment, a PVA / PAA salt copolymer hydrogel was assumed as the hydrophilic polymer constituting the gel film of the accelerated transport film, but the hydrophilic polymer was used. By including a particulate hygroscopic agent in the gel film, the _{effect of improving CO 2} permence and CO ₂ / H ₂ selectivity is more or less hydrophilic except for PVA / PAA salt copolymers. It can also be used with polymers such as the polyacrylic acid salt exemplified in the first embodiment. Therefore, the hydrophilic polymer constituting the gel film of the accelerated transport film is not limited to the hydrophilic polymers exemplified in Examples 1 and 2 above.

<2> In Examples 1 and 2 of the first embodiment, it is assumed that cesium carbonate is used as _{the CO 2 carrier, but in the present invention, a CO 2} carrier and a particulate hygroscopic agent are formed on a gel film of a hydrophilic polymer. The particle-like hygroscopic agent _{promotes the reaction between CO 2} and CO ₂ carriers, which is equivalent to the membrane performance (CO ₂ permit and CO ₂ selective permeability) exemplified in the first embodiment. _{Any CO 2} carrier capable of exhibiting a degree or higher film performance is not limited to a specific CO _{2 carrier.}

<3> In Examples 1 and 2 of the first embodiment, it is assumed that porous particles such as silica gel and graphite are used as the particulate hygroscopic agent, but CO is produced by the particulate hygroscopic agent in the gel film. _A particulate hygroscopic agent that promotes the reaction between 2 and CO ₂ carriers and can exhibit film performance equal to or better than the film performance _{(CO 2} permit and CO ₂ selective permeability) exemplified in the first embodiment. If so, the present invention is not limited to a specific particulate hygroscopic agent. For example, the material of the particulate hygroscopic agent is not limited to silica gel and graphite as long as it has the same hygroscopicity, and may be a silicon compound such as zeolite other than silica gel, other than graphite. It may be a carbon-based powder such as activated carbon.

In order to ensure the hygroscopicity of the hygroscopic particles, it is preferable that the specific surface area of the particles is large, but the particles do not necessarily have to be porous, and may have a shape having many protrusions on the surface, for example. ..

Further, in the first embodiment, when graphite particles are used, an embodiment in which the surface of the graphite particles is modified with a surfactant to reduce water repellency has been described in order to ensure hygroscopicity. However, even when a particulate hygroscopic agent other than graphite particles is used, it is preferable to perform a surface modification treatment using the same surfactant, if necessary.

Further, in the first embodiment, it is assumed that a particulate hygroscopic agent having a particle size classified to 75 μm or less by sieving is used, but some particles having a particle size exceeding 75 μm are mixed. However, when the thickness of the gel film is thicker than about 200 μm, the path passing through the gel film via the hygroscopic agent is not always formed as a defect. Therefore, the upper limit of the distribution range of the particle size of the gel film thickness may be larger than 75 μm depending on the gel film thickness.

<4> In the first embodiment, as a method for producing the accelerated transport film (the present production method), a _{sol solution composed of an aqueous solution containing a PVA / PAA salt copolymer, a CO 2} carrier, and a particulate hygroscopic agent is prepared. Then, the sol solution was cast on the hydrophilic PTFE porous membrane and then gelled to prepare the sol solution, but it may be prepared by a production method other than the production method. For example, a gel film of a PVA / PAA salt copolymer containing a particulate hygroscopic agent and _{not containing a CO 2} carrier may be formed and then impregnated with an aqueous solution containing _{a CO 2 carrier.}

Further, in the step of preparing the sol solution, the case where the _{hydrophilic polymer and the CO 2} carrier are added to the pure water to which the particulate hygroscopic agent is added first has been illustrated. And CO ₂ carriers may be added to pure water at the same time to prepare a sol solution. Further, a gel film prepared by casting a sol solution prepared by simultaneously adding a particulate hygroscopic agent and a hydrophilic polymer to pure water into a hydrophilic PTFE porous film and then gelling the gel film contains an aqueous solution containing _{a CO 2 carrier.} It may be invaded and produced.

<5> In the first embodiment, the case where the gel membrane is supported on the hydrophilic PTFE porous membrane has been described, but the gel membrane may be supported on the hydrophobic PTFE porous membrane.

<6> In the second embodiment, as one application of the CO ₂ separation device using this facilitated transport membrane has been described CO ₂ permeable membrane reactor, the CO ₂ separation device using this facilitated transport membrane, It can be used in a decarboxylation step in a hydrogen production process other than the membrane reactor, and further, it can be applied to other than the hydrogen production process, and is limited to the application examples exemplified in the second embodiment. is not it. Further, the supply-side gas (raw material gas) supplied to the accelerated transport membrane is not limited to the mixed gas exemplified in each of the above embodiments. That is, the main component gas of the mixed gas _{is not limited to hydrogen (H 2 ), but nitrogen (N 2} ), methane (CH ₄ ), and oxygen (CH 4), which permeate this accelerated transport membrane only by the dissolution / diffusion mechanism. It _{may be O 2} ) or the like.

<7> The mixing ratio of each component in the composition of the accelerated transport film, the film thickness of the gel film, and the like exemplified in each of the above embodiments are examples for easy understanding of the present invention, and the present invention is an example thereof. It is not limited to the numerical CO _{2 promoting transport membrane.}

CO ₂ facilitated transport membrane according to the present invention, as an example, decarboxylation process of hydrogen production process, in CO ₂ permeable membrane reactor, etc., the CO ₂ with high selectivity against hydrogen ratio from a mixed gas containing CO ₂ and H ₂ It can be used to separate.

1: Gel membrane 2: Hydrophilic porous membrane 3: Hydrophobic porous membrane 10: CO ₂ separator 11: CO ₂ accelerated transport membrane 12: Containers 12a, 12b: Bottom of container (upper bottom, lower bottom)
13: Supply side space 14: Permeation side space 15: 1st inlet 16: 2nd inlet 17: 1st outlet 18: 2nd outlet FG: Raw material gas EG: Raw material gas after _{CO 2 separation PG: Permeation} Gas SG, SG': Sweep gas

Claims (13)

1. _{A CO 2} promoting transport membrane _{characterized by containing a CO 2} carrier and a particulate hygroscopic agent in a gel film of a hydrophilic polymer.
2. _{The CO 2} promoting transport membrane according to claim 1, wherein the hygroscopic agent is porous particles.
3. _{The CO 2} promoting transport membrane according to claim 1 or 2, wherein the hygroscopic agent is dispersed in the gel membrane.
4. _{The CO 2} promoting transport membrane according to any one of claims 1 to 3, wherein the moisture absorbing agent has a particle size of 75 μm or less.
5. _{The CO 2} promoting transport membrane according to any one of claims 1 to 4, wherein the hygroscopic agent is a silicon compound.
6. The claim is that the hydrophilic polymer is a polymer selected from polyvinyl alcohol-polyacrylate copolymer, polyvinyl alcohol, polyacrylic acid, chitosan, polyvinylamine, polyallylamine, and polyvinylpyrrolidone. _{The CO 2-} promoted transport film according to any one of 1 to 5.
7. A claim, wherein the CO ₂ carrier is composed of at least one of an alkali metal carbonate, an alkali metal bicarbonate, an alkali metal hydroxide, and an amino acid. _{The CO 2} promoting transport film according to any one of 1 to 6.
8. _{The CO 2} promoting transport membrane according to any one of claims 1 to 7, wherein the gel membrane is a hydrogel.
9. _{The CO 2} promoting transport membrane according to any one of claims 1 to 8, wherein the gel membrane is supported on a hydrophilic porous membrane.
10. _{Using the CO 2} promoting transport film according to any one of claims 1 to 9, a mixed gas containing a predetermined main component gas and CO _{2 is supplied to the CO 2} promoting transport film, and the mixed gas is used as described above. A CO ₂ separation method, _{which comprises separating the CO 2} that has permeated the CO _{2 promoting transport film.}
11. _{The CO 2} promoting transport film according to any one of claims 1 to 9 is provided, a mixed gas containing a predetermined main component gas and CO _{2 is supplied to the CO 2} promoting transport film, and the mixed gas is used to supply the CO. _{2 A CO 2} separation device for separating the _{CO 2} that has permeated the accelerated transport film.
12. _{The method for producing a CO 2-} promoted transport membrane according to any one of claims 1 to 9.
    A step of preparing a sol solution consisting of an aqueous solution containing the hydrophilic polymer, the CO _{2 carrier, and the hygroscopic agent, and}
    A method for producing _{a CO 2-} promoted transport membrane, which comprises a step of casting the sol solution into a hydrophilic porous membrane and then gelling the sol solution to prepare the gel membrane.
13. _{The CO 2} promotion according to claim 12, wherein in the step of preparing the sol solution, the hydrophilic polymer and the CO ₂ carrier are added to pure water to which the hygroscopic agent has been added first and stirred. A method for manufacturing a transport membrane.

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