JP2013107076A - Carbon dioxide separation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon dioxide separation apparatus using a COtransportation promoting membrane capable of exerting sufficient membrane performance at a high temperature of 100°C or higher and under a pressurized condition.SOLUTION: In the carbon dioxide separation apparatus, a feed gas containing at least hydrogen, carbon dioxide and steam is sent to the feed gas side of the COtransportation promoting membrane 10 at a feed temperature of 100°C or higher, while the carbon dioxide having passed through the COtransportation promoting membrane 10 is taken out of the transmission side of the membrane. A gel layer obtained by adding cesium carbonate to a gel membrane of a polyvinyl alcohol-polyacrylic acid copolymer is supported on a hydrophilic porous membrane to form the COtransportation promoting membrane 10.

Description

The present invention dioxide to retrieve the raw material gas contains at least carbon dioxide and water vapor to a predetermined main component gas is supplied to the raw material side of the CO ₂ -facilitated transport membrane, the carbon dioxide that has passed through the CO ₂ -facilitated transport membrane from the permeate side The present invention relates to a carbon separator, and more particularly, to a carbon dioxide separator that separates carbon dioxide contained in a reformed gas for a fuel cell containing hydrogen as a main component at a high selection ratio with respect to hydrogen.

  In current reforming systems for hydrogen stations, hydrocarbons are reformed to hydrogen and carbon monoxide (CO) by steam reforming, and further, carbon is converted to hydrogen by reacting carbon monoxide with steam using a CO shift reaction. Manufacture.

However, these techniques has been developed as a large-scale hydrogen production processes for chemical plants, Nissan number 100,000 m ³ or more ones are usually large, yet installed in the factory, high-continuous Driving is assumed. On the other hand, in the hydrogen station that produces hydrogen on-site from natural gas and oil as an important infrastructure that will support the future hydrogen energy society and supplies hydrogen to fuel cell vehicles, etc., the scale, installation environment, and operation of hydrogen production The pattern is greatly different from the conventional large-scale hydrogen plant, and many problems resulting from it remain.

  As a performance problem, in the case of a hydrogen station, it is necessary to respond to frequent start / stop and load changes in response to hydrogen demand (specifically, the number of fuel cell vehicles to be supplied with hydrogen, etc.). In particular, the CO transformer having the largest size and the largest heat capacity among reforming systems needs to be improved in terms of start-up time and load response.

  In addition, even for DSS (daily start / stop) operation in home systems, which is essential for promoting the reforming of fuel cell reforming systems, the CO transformer is also used in reforming systems in terms of start-up time and load responsiveness. Many problems remain, and in particular, downsizing and lowering the temperature of the CO transformer are the biggest problems.

  In addition, the steam reforming method has a large gap with respect to the target in terms of size and start-up time for automotive applications, and the on-board reforming in the automotive industry is rather more efficient than steam reforming, which is highly efficient. There is a tendency to aim at practical use with a partial oxidation method with excellent temperature reactivity. However, in the partial oxidation method, although the reformer can be expected to be greatly reduced in size, since it is accompanied by a CO converter, downsizing of the CO converter is a major issue for practical use. Thus, it can be said that downsizing of the CO converter is a common problem not only for the hydrogen station but also for the fuel cell reforming system including for automobiles.

  Also, from the viewpoint of efficiency, when steam reforming is performed, a decrease in S / C (molar ratio of steam to carbon (raw hydrocarbon)) is desirable in terms of thermal efficiency, but due to restrictions on the chemical equilibrium of the CO shift reaction. Highly efficient low S / C conditions were not employed.

  As a cost issue, PSA (Pressure Swing Adsorption) accounts for the largest percentage of the total cost of the hydrogen station, so there is a reforming method that increases the hydrogen concentration that directly leads to cost reduction. It was desired. The reformer outlet gas composition contains about 10% carbon monoxide and carbon dioxide in addition to hydrogen. In the CO converter, carbon monoxide decreases, but carbon dioxide increases. In steam reforming + CO conversion), about 20% of carbon dioxide and less than 1% of carbon monoxide remain together with about 1% of methane, and a large and high-cost PSA system is installed for purification. I had to do it.

  In conventional CO converters, a large amount of CO conversion catalyst is required as a cause of hindering miniaturization and shortening of the start-up time due to restrictions on the chemical equilibrium of the CO conversion reaction shown in the following (Chemical Formula 1). Can be mentioned. As an example, a reforming system for a 50 kW PAFC (phosphoric acid fuel cell) requires 20 L of reforming catalyst, whereas a CO conversion catalyst requires 77 L, which is about four times as much as the catalyst. This is a major factor that hinders downsizing the CO transformer and shortening the startup time. The symbol “⇔” indicates a reversible reaction.

(Chemical formula 1)
CO + H ₂ O ＣＯ CO ₂ + H ₂

Therefore, the CO converter is provided with a CO ₂ facilitated transport membrane that selectively allows carbon dioxide to permeate, and the right-side carbon dioxide generated by the CO conversion reaction of (Chemical Formula 1) is efficiently removed outside the CO converter. As a result, the chemical equilibrium can be shifted to the hydrogen production side (right side), and a high conversion rate can be obtained at the same reaction temperature. As a result, carbon monoxide and carbon dioxide can be removed beyond the limit due to equilibrium constraints. It becomes possible. FIG. 21 and FIG. 22 schematically show this state. FIGS. 22 (A) and 22 (B) show changes in the concentrations of carbon monoxide and carbon dioxide with respect to the catalyst layer length of the CO converter with and without the CO ₂ facilitated transport membrane, respectively. ing.

The CO converter (CO ₂ permeable membrane reactor) equipped with the above CO ₂ facilitated transport membrane makes it possible to remove carbon monoxide and carbon dioxide beyond the limits due to equilibrium constraints. The PSA load and S / C can be reduced, and the cost and efficiency of the entire hydrogen station can be reduced. Further, by providing the CO ₂ facilitated transport film, the CO conversion reaction can be speeded up (higher SV), so that the reforming system can be downsized and the startup time can be shortened.

As a prior example of such a CO ₂ permeable membrane reactor, there is one disclosed in the following Patent Document 1 (or Patent Document 2 having the same contents by the same inventor).

The reforming systems proposed in Patent Documents 1 and 2 are directed to purifying reformed gas and water gas shift reaction generated when reforming a fuel such as hydrocarbon or methanol into hydrogen for a fuel cell vehicle on the vehicle. The present invention provides a CO ₂ facilitated transport membrane process useful for (CO conversion reaction), and four typical processes are shown in the same document. When hydrocarbons (including methane) are used as raw materials, carbon monoxide is selectively removed by selectively removing carbon dioxide using a membrane reactor equipped with a CO ₂ facilitated transport membrane in a water gas shifter (CO converter). It increases the reaction rate and lowers the carbon monoxide concentration and improves the purity of the produced hydrogen. In addition, carbon monoxide and carbon dioxide remaining in the generated hydrogen are reacted with hydrogen by a methanator and converted to methane to reduce the concentration, thereby preventing a decrease in efficiency due to poisoning of the fuel cell.

In Patent Documents 1 and 2, a hydrophilic polymer film such as PVA (polyvinyl alcohol) mainly containing a halogenated quaternary ammonium salt ((R) ₄ N ⁺ X ⁻ ) as a carbon dioxide carrier is used as the CO ₂ facilitated transport film. It is used. In Example 6 of Patent Documents 1 and 2, a PVA membrane having a film thickness of 49 μm and 50 wt% containing 50 wt% of tetramethylammonium fluoride salt as a carbon dioxide carrier and porous PTFE (tetrafluoride tetrafluoride) supporting the PVA membrane. A method for producing a CO ₂ facilitated transport film formed of a composite film made of an ethylene polymer) film is disclosed. In Example 7, a mixed gas (25% CO ₂ , 75% H ₂ ) was mixed at a total pressure. The membrane performance of the CO ₂ facilitated transport membrane when treated at 3 atm and 23 ° C. is disclosed. As the membrane performance, CO ₂ permeance R _CO2 is 7.2 GPU (= 2.4 × 10 ⁻⁶ mol / (m ² · s · kPa)), and CO ₂ / H ₂ selectivity is 19.

Patent Document 3 below discloses a CO ₂ absorbent composed of a combination of cesium carbonate and an amino acid as a CO ₂ facilitated transport film.

The method for producing the CO ₂ facilitated transport membrane described in Patent Document 3 is as follows. First, a commercially available amino acid is added to an aqueous solution of cesium carbonate in a concentration, and stirred well to prepare a mixed aqueous solution. Thereafter, the gel-coated surface of the porous PTFE membrane (47Φ) coated with the gel is immersed in the prepared mixed solution for 30 minutes or more, and then the membrane is slowly pulled up. A silicone membrane is placed on the sintered metal (to prevent the solution from leaking to the permeate side), and the above-mentioned hydrogel membrane of 47 mmΦ is placed on it, and a cell containing silicone packing is placed thereon and sealed. A supply gas is allowed to flow at a rate of 50 cc / min with respect to the CO ₂ facilitated transport membrane thus produced, and the lower side of the membrane is evacuated to lower the pressure to about 40 torr.

In Example 4 of Patent Document 3, a CO ₂ facilitated transport membrane comprising cesium carbonate and 2,3-diaminopropionate hydrochloride at a molar concentration of 4 (mol / kg), respectively, under a temperature condition of 25 ° C. The CO ₂ permeation rate is 1.1 (10 ⁻⁴ cm ³ (STP) / cm ² · s · cmHg), and the CO ₂ / N ₂ separation factor is 300. Incidentally, CO ₂ permeance _{R CO2,} as defined by the permeation rate per pressure difference, CO ₂ permeance _{R CO2} in Example 4 of Patent Document 3 is calculated as 110GPU, _CO in the embodiment 2 / Data regarding H ₂ selectivity is not disclosed.

Patent Document 4 below discloses a CO ₂ separation membrane composed of a cellulose acetate membrane to which alkali bicarbonate is added. However, the document 4 only describes CO ₂ / O ₂ selectivity, and does not disclose data on CO ₂ / H ₂ selectivity. Furthermore, the disclosed data was measured under conditions of low pressure (about 0.01 atmosphere), and data under a pressure condition of about several atmospheres is not disclosed.

Special table 2001-511430 gazette US Pat. No. 6,579,331 JP 2000-229219 A US Pat. No. 3,396,510

Since the CO ₂ facilitated transport membrane selectively separates carbon dioxide as a basic function, development for the purpose of absorbing or removing carbon dioxide causing global warming has also been performed. However, in consideration of application to a CO ₂ permeable membrane reactor, the CO ₂ facilitated transport membrane is required to have a certain performance or more with respect to the use temperature, CO ₂ permeance, CO ₂ / H ₂ selectivity, etc. . In other words, since the performance of the CO shift catalyst for use in the CO shift reaction tends to decrease with temperature, the use temperature is considered to be at least 100 ° C. In each of the above Patent Documents 1 to 3, the membrane performance is measured under a temperature condition of about 25 ° C., and a CO ₂ facilitated transport membrane exhibiting sufficient membrane performance even under a temperature condition of 100 ° C. or higher is used. It cannot be disclosed by the above patent documents.

CO ₂ permeance (one of the performance indicators of carbon dioxide permeability) shifts the chemical equilibrium of the CO shift reaction to the hydrogen production side (right side) and limits the carbon monoxide concentration and carbon dioxide concentration due to equilibrium constraints. Over a certain level, for example, about 0.1% or less, and in order to speed up the CO shift reaction (high SV), for example, 2 × 10 ⁻⁵ mol / (m ² · s · kPa) = 60 GPU or more) is considered necessary. However, the CO ₂ permeance of the CO ₂ facilitated transport membrane described in each of the above Patent Documents 1 and ₂ is a value that is significantly lower than 10 GPU, and the CO ₂ facilitated transport membrane exhibiting a CO ₂ permeance of about 60 GPU or more is It cannot be disclosed by patent literature. In addition, Patent Document 3 does not disclose CO ₂ / H ₂ selectivity and does not show that the CO ₂ permeance exhibits a capacity of 60 GPU or more under a temperature condition of 100 ° C. or more. In Patent Document 4, CO ₂ / H ₂ selectivity is not disclosed, and data under a pressure condition of about several atmospheres is not disclosed.

Furthermore, when the hydrogen produced by the CO shift reaction is discarded outside together with carbon dioxide through the CO ₂ facilitated transport membrane, a process of separating and recovering hydrogen from the waste gas is required. Since hydrogen is naturally smaller in molecular size than carbon dioxide, a membrane that can permeate carbon dioxide can also permeate hydrogen, but only carbon dioxide is selectively passed from the membrane supply side to the permeate side by the carbon dioxide carrier in the membrane. It is considered that a facilitated transport membrane that can be transported toward the surface is required, and the CO ₂ / H ₂ selectivity in that case is required to be about 90 to 100 or more.

However, the CO ₂ facilitated transport membranes described in Patent Documents 1 and 2 have a CO ₂ / H ₂ selectivity of 19 and cannot be said to have sufficient selectivity. In addition, since Patent Documents 3 and 4 do not disclose CO ₂ / H ₂ selectivity, Patent Documents 3 and 4 disclose a CO ₂ facilitated transport membrane exhibiting high CO ₂ / H ₂ selectivity. It is not possible.

By the way, the CO ₂ facilitated transport membrane needs moisture to sufficiently exhibit the facilitated transport function (membrane function) of carbon dioxide. More specifically, the reaction between carbon dioxide (CO ₂ ) and carbonate ions in the membrane usually indicates a chemical reaction represented by the following reaction path equation (Chemical Formula 2). From this, it can be seen that as the moisture in the membrane increases, the chemical equilibrium shifts to the product side (right side) and the permeation of carbon dioxide is promoted.

(Chemical formula 2)
CO ₂ + CO ₃ ²⁻ + H ₂ O → 2HCO ³⁻

However, when the operating temperature is higher than 100 ° C., the moisture in the membrane evaporates, and the membrane function, that is, the facilitated transport function of carbon dioxide is lowered. Such a decrease in membrane function has become a common sense of conventional facilitated transport membranes. On the other hand, the higher the temperature, the higher the rate of the chemical reaction, so the inventors of the present application can fully demonstrate the membrane function by ensuring the amount of water in the membrane by increasing the partial pressure of water vapor in the gas phase under pressure. Confirmed that it will be. At present, no carbon dioxide separation device is provided that exhibits a high CO ₂ separation function even under high temperature conditions where the operating temperature exceeds 100 ° C. or higher.

In view of the above problems, an object of the present invention is to provide a carbon dioxide separation apparatus using a CO ₂ facilitated transport membrane capable of exhibiting sufficient membrane performance under a high temperature and a pressurized condition of 100 ° C. or higher. .

In order to achieve the above object, a carbon dioxide separator according to the present invention supplies a raw material gas containing at least hydrogen, carbon dioxide and water vapor to a raw material side surface of a CO ₂ facilitated transport membrane at a supply temperature of 100 ° C. or more, A carbon dioxide separator that extracts carbon dioxide permeated through the CO ₂ facilitated transport membrane from a permeation side surface, wherein the CO ₂ facilitated transport membrane is formed on a polyvinyl alcohol-polyacrylic acid copolymer gel membrane with cesium carbonate or cesium bicarbonate. Alternatively, it is characterized in that a gel layer to which an additive made of cesium hydroxide is added is supported on a hydrophilic porous film.

According to the above feature of the carbon dioxide separator according to the present invention, since the polyvinyl alcohol-polyacrylic acid (PVA / PAA) copolymer gel film contains cesium carbonate (Cs ₂ CO ₃ ), the Cs ₂ CO ₃ functions as a carbon dioxide carrier that transports carbon dioxide from the high-concentration side interface of carbon dioxide to the low-concentration side interface of the PVA / PAA gel layer, which is a permeable substance, and is about 90-100 at a high temperature of 100 ° C. or higher The above hydrogen selectivity (CO ₂ / H ₂ ) and CO ₂ permeance of about 2 × 10 ⁻⁵ mol / (m ² · s · kPa) (= 60 GPU) or more can be achieved.

  Further, since the porous membrane carrying the PVA / PAA gel layer is hydrophilic, a gel layer with few defects can be stably produced, and high selectivity to hydrogen can be maintained. In general, when the porous membrane is hydrophobic, it is possible to prevent moisture in the PVA / PAA gel membrane from entering the pores in the porous membrane at 100 ° C. or lower and lowering the membrane performance. Since it is considered that the same effect can be expected even in a situation where moisture in the PVA / PAA gel membrane decreases, the use of a hydrophobic porous membrane is recommended. By using this, there are few defects and the high selectivity to hydrogen can be maintained for the following reasons.

When a cast solution composed of an aqueous solution of PVA / PAA copolymer and Cs ₂ CO ₃ is cast on a hydrophilic porous membrane, the pores of the porous membrane are filled with the solution, and the cast solution is further applied to the surface of the porous membrane. Applied. When the cast solution is gelled, not only the surface of the porous membrane but also the pores are filled with the gel layer, so that defects are less likely to occur, and the success rate of forming the gel layer is increased.

  Considering the ratio of the pores (porosity) and the fact that the pores are not perpendicular to the membrane surface but bends (flexibility), the gel layer in the pores has a large resistance to gas permeation. As compared with the gel layer on the surface of the porous membrane, the permeability is lowered 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 liquid, but the cast solution is applied only to the surface of the porous membrane and the pores are filled with gas. The gas permeance in the upper gel layer is expected to be higher in both hydrogen and carbon dioxide compared to the hydrophilic porous membrane.

  However, in the gel layer on the surface of the membrane, minute defects are likely to occur as compared with the gel layer in the pores, and the success rate of film formation is reduced. Since hydrogen has a much smaller molecular size than carbon dioxide, hydrogen has a significantly larger permeance than carbon dioxide at small defects. Except for the defective part, the permeance of carbon dioxide permeated by the facilitated transport mechanism is much larger than the permeance of hydrogen permeated by the physical dissolution and diffusion mechanism.

As a result, the selectivity for hydrogen (CO ₂ / H ₂ ) when using a hydrophobic porous membrane will be lower than when using a hydrophilic porous membrane. Therefore, from the viewpoint of practical use, the stability and durability of the CO ₂ facilitated transport membrane are very important, and it is advantageous to use a hydrophilic porous membrane having a high selectivity to hydrogen (CO ₂ / H ₂ ). Become. The use of the hydrophilic porous membrane can be realized on the assumption that high CO ₂ permeance can be achieved by adding Cs ₂ CO ₃ as a carbon dioxide carrier to the PVA / PAA gel layer.

Note that the difference in gas permeance due to the difference between the hydrophobic porous membrane and the hydrophilic porous membrane can be obtained even if the cast solution is impregnated after gelation without adding carbon dioxide carrier Cs ₂ CO ₃ in advance. It is presumed that the inner gel layer has the same resistance to large gas permeation and develops similarly.

From the above, according to the carbon dioxide separator having the above characteristics, a working temperature of 100 ° C. or higher, a CO ₂ permeance of about 2 × 10 ⁻⁵ mol / (m ² · s · kPa) (= 60 GPU) or higher, and 90 A CO ₂ / H ₂ selectivity of about ˜100 or more can be realized, and the CO transformer can be downsized, the startup time can be shortened, and the speed can be increased (higher SV).

The same effect can be obtained when cesium hydroxide is added as an additive instead of cesium carbonate. That is, by using the facilitated transport membrane including the gel layer to which cesium hydroxide is added for the separation of CO ₂ , the reaction shown in the following (Chemical Formula 3) occurs, and thereby, in the facilitated transport membrane. This is because the added cesium hydroxide is converted to cesium carbonate.

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

  The above (Chemical Formula 3) can be summarized as follows (Chemical Formula 4). That is, this indicates that the added cesium hydroxide is converted to cesium carbonate.

(Chemical formula 4)
CO ₂ + 2CsOH → Cs ₂ CO ₃ + H ₂ O

  Further, from the above (Chemical Formula 3), it can be seen that the same effect can be obtained when cesium bicarbonate is added as an additive instead of cesium carbonate.

  Further, in the carbon dioxide separator according to the present invention, in addition to the above characteristics, the gel layer has a cesium carbonate weight ratio of 65 wt% with respect to a total weight of the polyvinyl alcohol-polyacrylic acid copolymer gel membrane and cesium carbonate. Another feature is that the content is in the range of 85% by weight or less.

According to the characteristics of the carbon dioxide separator according to the present invention, an excellent CO ₂ permeance and an excellent CO ₂ / H ₂ selectivity value can be realized under a temperature condition of 100 ° C. or higher. Miniaturization, shortening of startup time, and speeding up (higher SV) are achieved.

Further, the carbon dioxide separator according to the present invention supplies the raw material gas containing at least hydrogen, carbon dioxide and water vapor to the raw material side surface of the CO ₂ facilitated transport membrane at a supply temperature of 100 ° C. or more, thereby promoting the CO ₂ facilitated transport. A carbon dioxide separator that extracts carbon dioxide that has permeated through a membrane from a permeation side surface, wherein the CO ₂ facilitated transport membrane is formed from rubidium carbonate, rubidium bicarbonate, or rubidium hydroxide on a polyvinyl alcohol-polyacrylic acid copolymer gel membrane. Another feature is that the gel layer to which the additive is added is supported on a hydrophilic porous membrane.

According to the above characteristics of the carbon dioxide separator according to the present invention, in the polyvinyl alcohol-polyacrylic acid (PVA / PAA) copolymer gel membrane, rubidium carbonate (Rb) which is a carbonate having a relatively high solubility in water. ₂ CO ₃ ) functions as a carbon dioxide carrier that transports carbon dioxide, which is a permeating substance, from the carbon dioxide high concentration side interface to the low concentration side interface of the PVA / PAA copolymer gel layer, at a high temperature of 100 ° C. or higher. It is possible to achieve a selectivity to hydrogen (CO ₂ / H ₂ ) of about 90 to 100 or more and a CO ₂ permeance of about 2 × 10 ⁻⁵ mol / (m ² · s · kPa) (= 60 GPU) or more. .

  The same effect can be obtained when rubidium hydroxide or rubidium bicarbonate is added instead of rubidium carbonate. This is because the same effect as that obtained when cesium carbonate is added is obtained when cesium hydroxide or cesium bicarbonate is added instead of cesium carbonate.

  In addition to the above feature, the carbon dioxide separator according to the present invention has another feature that the gel layer supported on the hydrophilic porous membrane is covered with a hydrophobic porous membrane.

According to the above feature of the carbon dioxide separator according to the present invention, the gel layer supported by the hydrophilic porous membrane is protected by the hydrophobic porous membrane, and the strength of the CO ₂ facilitated transport membrane during use is increased. As a result, sufficient membrane strength can be ensured even if the pressure difference between both sides of the CO ₂ facilitated transport membrane (inside and outside the reactor) is large (eg, 2 atm or more). Furthermore, since the gel layer is covered with a hydrophobic porous membrane, even if water vapor is condensed on the membrane surface of the hydrophobic porous membrane, the porous membrane is hydrophobic and water is repelled and penetrates into the gel layer. Is preventing. Therefore, the hydrophobic porous membrane can dilute the carbon dioxide carrier in the gel layer with water, and can prevent the thinned carbon dioxide carrier from flowing out of the gel layer.

  The carbon dioxide separator according to the present invention is characterized in that, in addition to the above characteristics, the gel layer has a crosslinked structure derived from an aldehyde group.

According to the above characteristics of the CO ₂ facilitated transport film according to the present invention, the cross-linked structure formed in the gel layer makes it difficult for defects to occur in the film, and as a result, the H ₂ permeance is greatly reduced. On the other hand, the CO ₂ permeance does not cause a decrease as much as the H ₂ permeance. Thus, it is possible to realize a facilitated transport membrane which exhibits a higher CO 2 _/ H ₂ selectivity.

At this time, glutaraldehyde or formaldehyde can be employed as a crosslinking agent to be added. In the case of adding glutaraldehyde, particularly high CO ₂ / H ₂ selectivity can be shown by adding about 0.008 to 0.015 g to 1 g of PVA / PAA copolymer.

  Further, the carbon dioxide separator according to the present invention is characterized in that, in addition to the above characteristics, the hydrophilic porous membrane has heat resistance of 100 ° C. or higher.

  According to the above feature of the carbon dioxide separator according to the present invention, it can be used in a wide temperature range from room temperature to 100 ° C. or more. Specifically, the hydrophilic porous membrane has heat resistance of 100 ° C. or higher, so that it can be used in a temperature region of 100 ° C. or higher.

In addition to the above characteristics, the CO ₂ facilitated transport membrane according to the present invention has a cylindrical shape in which both the gel layer and the hydrophilic porous membrane have the same axial center, and one membrane has The inner surface is brought into contact with the outer surface of the other film so as to surround the other film.

  At this time, a film made of ceramics such as alumina can be used as the hydrophilic porous film.

  Further, the gel layer can be formed outside the hydrophilic porous film so as to surround the hydrophilic porous film.

According to the configuration of the present invention, it is possible to realize a carbon dioxide separation apparatus using a CO ₂ facilitated transport membrane capable of exhibiting sufficient membrane performance at a high temperature of 100 ° C. or higher and a pressurized condition. ₂ A carbon dioxide separation method using a facilitated transport membrane can be provided.

The block diagram which shows typically the schematic structure in one Embodiment of the carbon dioxide separator which concerns on this invention Sectional view schematically showing the structure of an embodiment of a CO ₂ -facilitated transport membrane according to the present invention Process diagram showing the manufacturing method of the CO ₂ -facilitated transport membrane according to the present invention Sectional view schematically showing the structure of a comparative sample of a CO ₂ -facilitated transport membrane Configuration diagram of an experimental apparatus for evaluating the membrane performance of the CO ₂ facilitated transport membrane according to the present invention Figure shows the effect of improving CO 2 _/ H ₂ selectivity by use of a hydrophilic porous membrane of the CO ₂ -facilitated transport membrane according to the present invention (1) Illustrates the effect of improving CO 2 _/ H ₂ selectivity by use of a hydrophilic porous membrane of the CO ₂ -facilitated transport membrane according to the present invention (2) It shows the dependence on the pressure and the carrier concentration of the CO ₂ permeance _{R CO2} and _CO 2 / _{H 2} selectivity of the source gas CO ₂ facilitated transport membrane according to the present invention It shows the dependence on CO ₂ permeance _R carrier concentration of _CO2 and _CO 2 / _{H 2} selectivity of CO ₂ facilitated transport membrane according to the present invention It shows the dependence on CO ₂ permeance _{R CO2} and _CO 2 / _{H 2} pressure and operating temperature of the selectivity of the raw material gas of CO ₂ facilitated transport membrane according to the present invention It shows the dependence on CO ₂ permeance _{R CO2} and _CO 2 / _{H 2} selectivity of the use temperature of the CO ₂ -facilitated transport membrane according to the present invention It shows the dependence on pressure and water vapor mole% of CO ₂ permeance _{R CO2} and _CO 2 / _{H 2} selectivity of the source gas CO ₂ facilitated transport membrane according to the present invention Shows the time course of CO ₂ permeance _{R CO2} and _CO 2 / _{H 2} selectivity of CO ₂ facilitated transport membrane according to the present invention Graph showing the membrane performance of the prepared membrane of the present invention by the method of Example 1 of the second embodiment of the CO ₂ -facilitated transport membrane according to the present invention Graph showing the membrane performance of the prepared membrane of the present invention in a second embodiment the method of Example 2 of the CO ₂ -facilitated transport membrane according to the present invention Graph showing the membrane performance of the prepared membrane of the present invention in Example 3 of the method of the second embodiment of the CO ₂ -facilitated transport membrane according to the present invention A graph showing changes over time in membrane performance of the prepared membrane of the present invention by the method of Example 1 of the second embodiment of the CO ₂ -facilitated transport membrane according to the present invention Sectional view schematically showing the structure of a third embodiment of the CO ₂ -facilitated transport membrane according to the present invention Shows the dependence on a third embodiment of the CO ₂ permeance, _{H 2} permeance and _CO 2 / _{H 2} pressure of selectivity of the raw material gas of CO ₂ facilitated transport membrane according to the present invention Comparison diagram of CO ₂ permeance R _CO2 and CO ₂ / H ₂ selectivity over time in cylindrical and flat type facilitated transport membranes The figure which shows the flow of various gases in the CO transformer equipped with the CO ₂ facilitated transport film Comparison chart of changes in carbon monoxide and carbon dioxide concentrations versus the catalyst layer length of the CO converter with and without a CO ₂ facilitated transport membrane

  An embodiment of a carbon dioxide separator according to the present invention (hereinafter referred to as “the present apparatus” as appropriate) will be described with reference to the drawings.

The apparatus, as shown in FIG. 1, includes a CO transformer (CO ₂ permeable membrane reactor) 20 having a CO ₂ -facilitated transport membrane 10, the carbon dioxide is selectively separated by the CO ₂ -facilitated transport membrane 10 Thereafter, the processed gas FG ′ is exhausted from the exhaust path.

The CO ₂ permeable membrane reactor 20 is configured to convert, for example, carbon monoxide contained in the raw material gas FG other than hydrogen in a steam reformer (not shown) into CO conversion reaction shown in the above (Chemical Formula 1). The carbon dioxide generated by the CO shift reaction is selectively removed to the outside of the CO shift converter by the CO ₂ facilitated transport membrane 10 to shift the chemical equilibrium of the CO shift reaction to the hydrogen generation side. It is possible to remove carbon monoxide and carbon dioxide beyond the limits due to equilibrium constraints with high conversion at the same reaction temperature.

In the apparatus of the present invention, the performance of the CO shift catalyst for the CO shift reaction tends to decrease with temperature. Therefore, the operating temperature is considered to be at least 100 ° C., and is supplied to the raw material side of the CO ₂ facilitated transport membrane 10. The supply temperature of the raw material gas FG is 100 ° C. or higher. Thus, the feed gas FG is the upstream side of the CO ₂ -facilitated transport membrane 10, after being adjusted to a temperature suitable for catalytic activity in CO conversion catalyst, the CO ₂ -facilitated transport membrane 10 through the CO shift reaction (exothermic reaction) Supplied. Note that the raw material gas may be supplied to the CO ₂ facilitated transport film 10 after performing a process of lowering the raw material gas temperature after the CO shift reaction.

The partial pressure of the permeated gas containing carbon dioxide that has passed through the CO ₂ -facilitated transport membrane 10 by lowering, in order to maintain the transmission driving force of CO ₂ facilitated transport membrane 10, for discharging the permeate gas PG to the outside, CO ₂ A sweep gas SG passage 21 is provided along the outer side surface (permeation side surface) of the facilitated transport film 10, and a sweep gas SG such as air is fed from one side of the passage and permeated with the sweep gas SG from the other side. The gas PG is discharged. Specifically, for example, the CO ₂ permeable membrane reactor 20 is configured as a double tube structure, the inner tube is configured as a CO transformer, and the space between the inner tube and the outer tube is configured as a sweep gas passage 21.

The raw material gas FG is sent to the CO ₂ permeable membrane reactor 20 from the upstream steam reformer at a predetermined pressure.

Next, the CO ₂ facilitated transport membrane 10 used in the apparatus of the present invention (hereinafter referred to as “the present invention membrane 10” as appropriate) will be described.

[First embodiment of the membrane of the present invention]
1st Embodiment of this invention film | membrane is described with reference to FIGS. 2-13 and Table 1 below.

The membrane of the present invention is a CO ₂ facilitated transport membrane containing a carbon dioxide carrier in a gel membrane containing water, and has a use temperature of 100 ° C. or higher, high carbon dioxide permeability and CO ₂ / H ₂ selectivity. _{This is} a CO ₂ facilitated transport membrane applicable to a _two- permeable membrane reactor. Furthermore, the membrane of the present invention employs a hydrophilic porous membrane as a support membrane that supports a gel membrane containing a carbon dioxide carrier in order to stably realize high CO ₂ / H ₂ selectivity.

Specifically, the membrane of the present invention uses a polyvinyl alcohol-polyacrylic acid (PVA / PAA) copolymer as a membrane material, and cesium carbonate (Cs ₂ CO ₃ ) as a carbon dioxide carrier. Further, in the membrane of the present invention, as schematically shown in FIG. 2, the hydrophilic porous membrane 2 carrying the PVA / PAA gel membrane 1 containing carbon dioxide carrier is divided into two hydrophobic porous membranes 3 and 4. It is composed of a three-layer structure that is sandwiched. Hereinafter, in order to distinguish a PVA / PAA gel membrane containing a carbon dioxide carrier from a PVA / PAA gel membrane not containing a carbon dioxide carrier, and a membrane of the present invention having a structure comprising two hydrophobic porous membranes, It is abbreviated as “impregnated gel film” as appropriate. Further, based on the total weight of PVA / PAA and Cs ₂ CO _{3 in} the impregnated gel film, PVA / PAA is present in the range of about 20 to 80% by weight in the impregnated gel film, and Cs ₂ CO ₃ is It is present in the range of about 20-80% by weight.

  The hydrophilic porous membrane preferably has, in addition to hydrophilicity, heat resistance of 100 ° C. or higher, mechanical strength, and adhesion to the impregnated gel membrane, and further has a porosity (porosity) of 55% or more, 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 having these conditions.

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

  Next, an embodiment of a method for producing a film of the present invention (method of the present invention) will be described with reference to FIG.

First, a cast solution composed of an aqueous solution containing a PVA / PAA copolymer and Cs ₂ CO ₃ is prepared (step 1). In more detail, 1 g of PVA / PAA copolymer (for example, a temporary name SS gel manufactured by Sumitomo Seika), 2.33 g of Cs ₂ CO ₃ , weighed in a sample bottle, and 20 ml of water was added thereto at room temperature. And cast for 5 days to obtain a cast solution.

  Next, in order to remove bubbles in the cast solution obtained in Step 1, centrifugation (rotation speed: 5000 rpm for 30 minutes) is performed (Step 2).

  Next, the cast solution obtained in step 2 is mixed with a hydrophilic PTFE porous membrane (for example, manufactured by Sumitomo Electric, WPW-020-80, film thickness 80 μm, pore diameter 0.2 μm, porosity 75%) and hydrophobic PTFE porous On the hydrophilic PTFE porous membrane side surface of the layered porous membrane in which two membranes (for example, made by Sumitomo Electric, Fluoropore FP010, film thickness 60 μm, pore diameter 0.1 μm, porosity 55%) are overlapped with an applicator Cast (step 3). In addition, the cast thickness in the sample of the Example mentioned later is 500 micrometers. Here, the cast solution penetrates into the pores in the hydrophilic PTFE porous membrane, but the penetration stops at the boundary surface of the hydrophobic PTFE porous membrane, and the cast solution does not penetrate to the opposite surface of the layered porous membrane, There is no casting solution on the side surface of the porous porous membrane of the layered porous membrane, and the handling becomes easy.

  Next, the hydrophilic PTFE porous membrane after casting is naturally dried overnight at room temperature, and then the cast solution is gelled to form a gel layer (step 4). In this method, since the cast solution is cast on the hydrophilic PTFE porous membrane side surface of the layered porous membrane in Step 3, the gel layer is formed on the surface (cast surface) of the hydrophilic PTFE porous membrane in Step 4. In addition to being formed in the pores, defects (micro-defects such as pinholes) are less likely to occur, and the success rate of forming the gel layer is increased. In Step 4, 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 crosslinking is performed.

  Next, on the gel layer side of the hydrophilic PTFE porous membrane surface obtained in step 4, the same hydrophobic PTFE porous membrane as that of the layered porous membrane used in step 3 is overlaid and schematically shown in FIG. As shown, a membrane of the present invention having a three-layer structure comprising a hydrophobic PTFE porous membrane / gel layer (impregnated gel membrane supported on a hydrophilic PTFE porous membrane) / hydrophobic PTFE porous membrane is obtained (step 5). In FIG. 2, the state in which the impregnated gel film 1 is filled in the pores of the hydrophilic PTFE porous film 2 is schematically displayed in a straight line.

As described above, the membrane of the present invention produced through the steps 1 to 5 can be applied to a CO ₂ permeable membrane reactor, that is, a use temperature of 100 ° C. or higher, 2 × 10 ⁻⁵ mol / ( CO ₂ permeance of about m ² · s · kPa) (= 60 GPU) or more and CO ₂ / H ₂ selectivity of about 90 to 100 or more can be realized.

  Further, by forming a three-layer structure in which the gel layer is sandwiched between the hydrophobic PTFE porous membranes, one hydrophobic PTFE porous membrane is used in Step 3 and Step 4, and is a hydrophilic PTFE porous membrane carrying the impregnated gel membrane. The other hydrophobic PTFE porous membrane is used to protect the impregnated gel membrane from the other surface side.

  Furthermore, even if water vapor is condensed on the surface of the hydrophobic PTFE porous membrane, the PTFE porous membrane is hydrophobic and prevents water from being repelled and penetrating into the impregnated gel membrane. Therefore, the other PTFE porous membrane can dilute the carbon dioxide carrier in the impregnated gel membrane with water and prevent the thinned carbon dioxide carrier from flowing out of the impregnated gel membrane.

  Hereinafter, the film performance of specific examples will be described.

  First, the film composition of each sample of an example using a hydrophilic PTFE porous film and a comparative example using a hydrophobic PTFE porous film as a porous film carrying an impregnated gel film will be described.

The sample of the example was manufactured by the above-described manufacturing method. The blending ratio of (PVA / PAA: Cs ₂ CO ₃ ) is (30% by weight: 70% by weight) in the order of description. Hereinafter, the ratio of the carrier weight to the total weight of the copolymer weight and the carrier weight is referred to as “carrier concentration”. That is, in the above example, the carrier concentration is 70%.

The sample of the comparative example was prepared by using one layer of a hydrophobic PTFE porous membrane in place of the layered porous membrane of the hydrophilic PTFE porous membrane and the hydrophobic PTFE porous membrane in the above-described production method. Therefore, in the sample of the comparative example, as schematically shown in FIG. 4, a PVA / PAA gel film 1 containing a carbon dioxide carrier is sandwiched between two hydrophobic porous films 3 and 4. Composed of structure. The blending ratio of (PVA / PAA: Cs ₂ CO ₃ ) is the same as in the example.

  Next, the configuration of the experimental apparatus and the experimental method for evaluating the film performance of each sample of the example and the comparative example will be described with reference to FIG.

As shown in FIG. 5, each sample 10 has two fluororubber gaskets between a raw material side chamber 12 and a permeation side chamber 13 of a stainless steel flow type gas permeation cell 11 (membrane area: 2.88 cm ² ). It is fixed by using it as a sealing material. A source gas (mixed gas composed of CO ₂ , H ₂ , H ₂ O) FG is supplied to the source side chamber 12 at a flow rate of 2.24 × 10 ⁻² mol / min, and a sweep gas (Ar gas) SG is supplied at 8 .Supply to the permeation side chamber 13 at a flow rate of 18 × 10 ⁻⁴ mol / min. The pressure in the raw material side chamber 12 is adjusted by a back pressure regulator 15 provided on the downstream side of the cooling trap 14 in the middle of the exhaust gas discharge path. The pressure in the transmission side chamber 13 is atmospheric pressure. The gas composition after the water vapor in the sweep gas SG ′ discharged from the permeation side chamber 13 is removed by the cooling trap 16 is quantified by the gas chromatograph 17 and the permeance of CO ₂ and H ₂ from this and the flow rate of Ar in the sweep gas SG. [Mol / (m ² · s · kPa)] is calculated, and the CO ₂ / H ₂ selectivity is calculated from the ratio. A back pressure regulator 19 is also provided between the cooling trap 16 and the gas chromatograph 17, thereby adjusting the pressure in the permeation side chamber 13.

In order to simulate the raw material gas in the CO transformer, the raw material gas FG is obtained by using a first mixed gas composed of CO ₂ , H ₂ , and H ₂ O as follows: CO ₂ : 5.0%, H ₂ : 45%, H ₂ O: The mixture ratio was adjusted to 50% (mol%). Specifically, water is quantified in a mixed gas flow (flow rate at 25 ° C .: 200 cm ³ / min, 8.18 × 10 ⁻³ mol / min) composed of 10% CO ₂ and 90% H ₂ (mol%). It was fed by the liquid feed pump 18 (flow rate: 0.256 cm ³ / min, 1.42 × 10 ⁻² mol / min), heated to 100 ° C. or more to evaporate the water, and the mixed gas having the above mixing ratio was This was prepared and supplied to the raw material side chamber 12.

The sweep gas SG is supplied in order to reduce the partial pressure on the permeate side chamber side of the gas to be measured (CO ₂ , H ₂ ) that permeates the sample membrane and maintain the permeation driving force, and is a gas type different from the gas to be measured. (Ar gas) is used. Specifically, Ar gas (flow rate at 25 ° C .: 20 cm ³ / min, 8.13 × 10 ⁻⁴ mol / min) was supplied to the permeation side chamber 13.

  Although not shown, in order to maintain the use temperature of the sample film and the temperatures of the raw material gas FG and the sweep gas SG at a constant temperature, the flow type gas permeable cell 11 to which the sample film is fixed and the gas are heated. The preheating coil is immersed in an oil thermostat set at a predetermined temperature.

Next, FIGS. 6 and 7 show the selectivity of CO ₂ permeance R _CO2 , H ₂ permeance R _H2 , and CO ₂ / H ₂ for each sample of (1) Examples and (2) Comparative Examples. The result of having measured the pressure of the raw material gas FG (described as “raw material side pressure” on the graph. The same applies hereinafter) in a pressure range of 200 kPa to 400 kPa is shown. FIG. 6 shows a measurement temperature of 160 ° C., and FIG. 7 shows a measurement temperature of 180 ° C. Moreover, the pressure value which the back pressure regulator 15 for adjusting the pressure of the raw material side chamber 12 showed as the value of the raw material side pressure on the graph was employ | adopted.

6 and 7, the H ₂ permeance is higher in the entire pressure range in the comparative sample using the hydrophobic PTFE porous membrane than in the example using the hydrophilic PTFE porous membrane. However, in the CO ₂ permeance and the CO ₂ / H ₂ selectivity, it can be seen that the sample of the example is significantly improved over the sample of the comparative example. This is because, in the case of a hydrophilic membrane, when the cast solution is cast on the membrane, the gel layer is filled not only on the surface of the PTFE porous membrane but also in the pores, so that defects (minute defects such as pinholes) occur. This is considered to be because the gas permeance, particularly the H ₂ permeance, is suppressed from increasing through the minute defect. On the other hand, in the case of a hydrophobic membrane, the casting liquid does not penetrate into the pores of the membrane and is applied to the surface of the membrane, so that defects are likely to occur and the H ₂ permeance is increased. Is considered to decrease.

  In addition, according to FIG.6 and FIG.7, even if it changes measurement temperature, it turns out that the same characteristic is shown.

In addition, in the CO ₂ facilitated transport membrane disclosed in Patent Documents 1 and 2, a use temperature of 100 ° C. or more, a CO ₂ permeance of about 2 × 10 ⁻⁵ mol / (m ² · s · kPa), and While none of the CO ₂ / H ₂ selectivity of about 90-100 or more is satisfied, the samples of the examples shown in FIGS. 6 and 7 generally satisfy all the requirements in the entire pressure range. Yes. In addition, the sample of the comparative example also shows CO ₂ permeance of about 2 × 10 ⁻⁵ mol / (m ² · s · kPa) or more under the operating temperature condition of 100 ° C. or higher. In the sample of Comparative Example, it has been suggested that reduction of _CO 2 / _{H 2} selectivity at least 300kPa increases.

Considering the results of FIG. 6 and FIG. 7, the membrane of the present invention having a PVA / PAA gel membrane containing Cs ₂ CO ₃ as compared with the CO ₂ facilitated transport membrane disclosed in Patent Documents 1 and ₂ However, CO ₂ permeance can be improved under high temperature conditions of 100 ° C. or higher. Then, in particular the supporting layer by a hydrophilic porous membrane, CO ₂ permeance and CO 2 _/ H value of ₂ selectivity can be remarkably improved.

  In the following, data acquisition was performed using the membrane of the present invention having a configuration in which an impregnated gel membrane is supported by a hydrophilic PTFE porous membrane as in the Examples.

Next, FIG. 8 shows CO ₂ permeance R _CO2 , H ₂ permeance R _H2 , and CO ₂ / H ₂ selectivity of each sample produced by changing the carrier concentration from 50 wt% to 85 wt%, and the source gas FG. The mixing ratio and the measurement temperature are the same as in FIG. 6, and the result of measuring the pressure of the raw material gas FG in a pressurized state in the range of 200 kPa to 600 kPa is shown.

From FIG. 8, in the measurement temperature of 160 ° C., CO ₂ permeance _{R CO2} when the carrier concentration of 70 wt% is maximized, also be CO ₂ permeance _{R CO2} is maximized when the pressure of the feed gas FG is 500kPa I understand. When the carrier concentration is 80% or less and when the carrier concentration is 85% and the pressure of the source gas FG is 300 kPa or more, both are 5.0 × 10 ⁻⁵ mol / (m ² · It can be seen that a high CO ₂ permeance of (s · kPa) or higher is exhibited.

Further, it can be seen that the H ₂ permeance R _H2 tends to slightly decrease as the pressure of the raw material gas FG increases as a whole, except when the carrier concentration is 50 wt%.

Furthermore, as shown in FIG. 8, when the carrier concentration is 70 wt% or more and 80 wt% or less, CO ₂ / H ₂ selectivity of about 90 to 100 or more is exhibited in any case where the pressure of the source gas FG is 200 to 600 kPa. I understand that.

That is, from the result of FIG. 8, according to the film of the present invention, the use temperature is adjusted to 100 ° C. or higher (160 ° C.), 2 × 10 ⁻⁵ mol / (m ² · s · kPa) (= 60 GPU) or more CO ₂ permeance and 90 to 100 or more CO ₂ / H ₂ selectivity can be realized. For this reason, the membrane of the present invention can be applied to a CO ₂ permeable membrane reactor. In particular, it has been suggested that high CO ₂ / H ₂ selectivity is exhibited over the entire pressure range within the range of 70 wt% to 80 wt%.

FIG. 9 is a graph showing the relationship between the carrier concentration and the CO ₂ permeance R _{CO2 and} the relationship between the carrier concentration and the CO ₂ / H ₂ selectivity, with the raw material gas pressure being constant (501.3 kPa). is there. Note that the mixing ratio of the source gas FG and the measurement temperature were the same as in FIG.

FIG. 9 shows that both the CO ₂ permeance and the CO ₂ / H ₂ selectivity show the highest values when the carrier concentration is 70 wt%. That is, according to FIG. 9, it can be seen that the CO ₂ permeance and the CO ₂ / H ₂ selectivity both depend on the carrier concentration. In particular, when the membrane of the present invention is used as a CO ₂ facilitated transport membrane, the ability can be maximized by setting the carrier concentration to 70 wt%.

FIG. 10 shows CO 2 when the measurement temperature is changed within the range of 125 ° C. or more and 200 ° C. or less under the condition that the carrier concentration is 70 wt% and the mixing ratio of the raw material gas FG is the same as in FIG. ₂ permeance R _CO2 , H ₂ permeance R _H2 , and CO ₂ / H ₂ selectivity are shown as a result of measuring the pressure of the raw material gas FG in the raw material side chamber 12 in a pressure range of 200 kPa to 600 kPa.

According to FIG. 10, when the measurement temperature is 160 ° C., the CO ₂ permeance R _CO2 is the largest. _Moreover, CO for 2 / _{H 2} selectivity, _CO 2 / _H is larger ₂ selectivity measured temperature is at 160 ° C. and 180 ° C., _CO 2 / _{H 2} selectivity than the temperature it falls increased It can be seen that decreases. That is, according to FIG. 10, it can be seen that the CO ₂ permeance and the CO ₂ / H ₂ selectivity also depend on the measurement temperature. In particular, when the membrane of the present invention is used as a CO ₂ facilitated transport membrane, it can be seen that the ability can be maximized by installing the membrane of the present invention at a temperature of 160 ° C. Thereby, according to the membrane of the present invention, compared with the conventional CO ₂ facilitated transport membrane disclosed in Patent Documents 1 and ₂ , high CO ₂ permeance and high under sufficiently high temperature conditions (125 ° C. to 200 ° C.) CO ₂ / H ₂ selectivity can be achieved, suggesting that good values are achieved especially at 140 ° C. to 180 ° C.

The present invention film even when the measurement temperature is 200 ° C., CO ₂ permeance _{R CO2} shows a ^{1.0 × 10 -4 mol / (m} 2 · s · kPa) about value, It can be seen that the CO ₂ permeance is about 2 × 10 ⁻⁵ mol / (m ² · s · kPa) or more. It can be seen that the CO ₂ permeance value does not change so much even when the pressure of the raw material gas FG is changed under a constant temperature condition.

Furthermore, FIG. 10 shows that CO ₂ / H ₂ selectivity shows a value close to 100 under a pressure of 300 kPa under a high temperature condition of 200 ° C. That is, even under a high temperature condition of about 200 ° C., it is found that can achieve the applicable CO ₂ -facilitated transport membrane to CO ₂ permeable membrane reactor.

FIG. 11 is a graph showing the relationship between the measurement temperature and CO ₂ permeance R _{CO2 and} the relationship between the measurement temperature and CO ₂ / H ₂ selectivity, with the raw material gas pressure being constant (501.3 kPa). is there. Note that the mixing ratio of the source gas FG and the measurement temperature were the same as in FIG.

According to FIG. 11, it can be seen that when the measurement temperature is 160 ° C., both the CO ₂ permeance and the CO ₂ / H ₂ selectivity show the highest values. That is, according to FIG. 11, it can be seen that both the CO ₂ permeance and the CO ₂ / H ₂ selectivity depend on the height of the measurement temperature. In particular, when the membrane of the present invention is used as a CO ₂ facilitated transport membrane, its ability can be maximized by using it at a temperature of 160 ° C.

FIG. 12 shows the CO ₂ permeance R _CO2 , H ₂ permeance R _H2 , and CO ₂ / H ₂ selectivity of the sample prepared with a carrier concentration of 70 wt%, the mixing ratio of the raw material gas FG and the measurement temperature as shown in FIG. When the water vapor mol% was changed to 20%, 30%, 50%, 70%, and 90% under the same conditions, the result of measuring the pressure of the raw material gas FG in a pressurized state in the range of 200 kPa to 600 kPa Show. Note that, _{specifically,} a mixed gas consisting of CO _2, H 2, _{H 2} O, the mole% of CO ₂ was fixed to 5%, mole% of the sum of _{H 2} and _{H 2} O becomes 95% Thus, the measurement was performed by changing the mol% of H _{2 and} the mol% of H ₂ O (water vapor mol%), respectively.

According to FIG. 12, it can be seen that the higher the water vapor mol%, the higher the CO ₂ permeance value, and conversely, the lower the water vapor mol%, the lower the CO ₂ permeance value. Even when the water vapor mol% is reduced to about 30%, the CO ₂ permeance of about 1 × 10 ⁻⁴ mol / (m ² · s · kPa) under the pressure condition of the raw material gas FG of 400 kPa. Is shown.

In addition, although the value of H ₂ permeance changes greatly when the water vapor mol% is 20%, there is not much difference in other values. On the other hand, it can be seen that the CO ₂ / H ₂ selectivity decreases almost entirely as the water vapor mol% decreases. And even if water vapor mol% is set to 30%, CO ₂ / H ₂ selectivity of about 100 is shown under the pressure condition of the raw material gas FG of 400 kPa.

Thus, the graph of FIG. 12, even under the conditions set low steam mol% to less than 30%, the membrane of the present invention shows a superior performance, the applicable CO ₂ -facilitated transport membrane to CO ₂ permeable membrane reactor It can be seen that it can be realized. Therefore, the apparatus of the present invention can exhibit CO ₂ separation performance even when the water vapor mol% of the raw material gas is low.

FIG. 13 is a graph showing the long-term performance of the membrane of the present invention. When the source gas is adjusted to a mixing ratio (mol%) of CO ₂ : 5%, H ₂ : 45%, H ₂ O: 50%, the pressure of the source gas is 351.03 kPa, and the carrier concentration is 70 wt% , CO ₂ permeance R _CO2 , and CO ₂ / H ₂ selectivity values over time.

According to FIG. 13, the value of CO ₂ permeance R _CO2 did not show a great change over time, and was about 1.6 × 10 ⁻⁴ mol / (m ² · s · kPa). . Similarly, the CO ₂ / H ₂ selectivity did not show a great change over time and showed a value of about 100. Thus, according to the membrane of the present invention, the CO ₂ facilitated transport membrane that can be applied to a CO ₂ permeable membrane reactor that exhibits excellent performance over a long period of time without significantly deteriorating with time. Can be realized.

Table 1 below shows the CO ₂ permeance and H ₂ permeance when the membrane material is the same (PVA / PAA copolymer) and the carbon dioxide carrier is various carbonates other than Cs ₂ CO _3. , And CO ₂ / H ₂ selectivity values are compared with the membrane of the present invention. In Table 1, the above data was measured when carbonates of Na, K, and Rb were used as carbon dioxide carriers in addition to the carbonate of Cs used in the membrane of the present invention. In either case, the raw material gas pressure was 401.33 kPa, the measurement temperature was 160 ° C., and the raw material gas was a CO ₂ : 5.0%, H ₂ : 45%, H ₂ O: 50% mixing ratio (moles). %) To measure each data. Each film was manufactured by the same method as the above-described method for manufacturing the film of the present invention.

According to the results shown in Table 1, the CO ₂ permeance was very low and high H ₂ permeance when using the Na ₂ CO ₃ membrane. This is probably because Na ₂ CO ₃ has a low solubility in water (see Table 1), so that crystals were formed when the cast film was crosslinked at 120 ° C., and a uniform film could not be obtained. . Further, in the case of the K ₂ CO ₃ membrane, a high CO ₂ permeance was obtained, but since the membrane was prone to defects, the H ₂ permeance was increased, and a high CO ₂ / H ₂ selectivity was not obtained. On the other hand, in the membrane containing Rb ₂ CO ₃ and Cs ₂ CO ₃ (see Table 1) having high solubility in water, good results were obtained for both CO ₂ permeance and CO ₂ / H ₂ selectivity.

From the above, it is clear that carbonates with high solubility in water function efficiently as CO ₂ carriers even at high temperatures, and membranes containing them are less prone to defects and exhibit high CO ₂ permeability and selectivity. Became. In particular, according to the membrane of the present invention using Cs ₂ CO ₃ as a carrier, a CO ₂ facilitated transport membrane exhibiting high CO ₂ permeance and high CO ₂ / H ₂ selectivity can be realized. Therefore, the device of the present invention can exhibit a high CO ₂ separation capability by including such a CO ₂ facilitated transport membrane.

[Second Embodiment of the Film of the Present Invention]
A second embodiment of the film of the present invention (hereinafter referred to as “this embodiment” as appropriate) will be described with reference to FIGS. 14 to 17. Note that this embodiment is different from the first embodiment of the film of the present invention only in a part of the structure of the film of the present invention and the method of the present invention. Omit.

  In this embodiment, the content of the process (the said process 1) which produces a cast solution differs compared with 1st Embodiment. In the present embodiment, the following three steps are performed as a step (cast solution preparation step) corresponding to step 1 of the first embodiment, and these are referred to as Examples 1 to 3, respectively.

Example 1
First, after adding 20 g of water to 1 g of a PVA / PAA copolymer (for example, a temporary name SS gel manufactured by Sumitomo Seika), the gel is dissolved by stirring at room temperature. Next, after adding about 0.008-0.0343g of glutaraldehyde to this, it stirs for 15 hours on 95 degreeC temperature conditions. Then, to obtain a cast solution by stirring further at room temperature was added 2.33g of _Cs 2 CO ₃ thereto. That is, in Example 1, a cast solution is prepared by performing a gel dissolution step, a glutaraldehyde addition step, a stirring step at a high temperature, a Cs ₂ CO ₃ addition step, and a stirring step at room temperature in this order.

(Example 2)
First, after adding 20 g of water to 1 g of the PVA / PAA copolymer, the gel is dissolved by stirring at room temperature. Next, 2.33 g of Cs ₂ CO ₃ and about 0.008 to 0.0343 g of glutaraldehyde are added thereto, and the mixture is stirred and dissolved at room temperature. Then, a cast solution is obtained by stirring for 15 hours under a temperature condition of 95 ° C. That is, in Example 2, a cast solution is prepared by performing a gel dissolution step, a glutaraldehyde and Cs ₂ CO ₃ addition step, a stirring step at room temperature, and a stirring step at high temperature in this order.

(Example 3)
First, after adding 20 g of water to 1 g of the PVA / PAA copolymer, the gel is dissolved by stirring at room temperature. Next, 2.33 g of Cs ₂ CO ₃ and about 0.008 to 0.0343 g of glutaraldehyde are added to this, and then dissolved by stirring at room temperature to obtain a cast solution. That is, in Example 3, a cast solution is prepared by performing a gel dissolution step, a glutaraldehyde and Cs ₂ CO ₃ addition step, and a stirring step at room temperature in this order.

In any of Examples 1 to 3, after preparing the cast solution, a CO ₂ facilitated transport membrane is obtained using the same method as in the step (steps 2 to 4) described in the first embodiment. That is, after centrifuging to remove bubbles in the cast solution, a porous porous PTFE porous membrane (film thickness 60 μm) and a hydrophilic PTFE porous film (film thickness 80 μm) are laminated on a glass plate. On the surface of the membrane on the hydrophilic PTFE porous membrane side, the above cast solution is cast with a thickness of 500 μm using an applicator. Then, it is dried overnight at room temperature. Then, by holding approximately 2 hours further this at a high temperature of about 120 ° C., to obtain a CO ₂ facilitated transport membrane.

  Hereafter, the film | membrane performance of this invention film | membrane manufactured by the method of each of these Examples 1-3 is demonstrated. The film composition is the same as in the first embodiment, and the carrier concentration is 70 wt%, and the experimental apparatus and experimental method for evaluating the film performance are the same as in the first embodiment.

FIG. 14 shows (a) CO ₂ permeance R _CO2 , (b) H ₂ permeance R _H2 , and (c) CO ₂ / by the membrane of the present invention produced using the cast solution produced by the method of Example 1. of H ₂ selectivity, showing the results of measurement of the feed side pressure in a pressurized state ranging from 200KPa～600kPa. In addition, in FIG. 14, each data was measured by changing the addition amount of glutaraldehyde added at the time of casting solution preparation. That is, the experiment was performed with three patterns of (1) 0.008 g, (2) 0.0153 g, and (3) 0 g (no addition) as the amount of glutaraldehyde added. In the graph, glutaraldehyde is abbreviated as “GA” (the same applies to the following graphs).

Further, as experimental conditions, the temperature condition is 160 ° C., the raw material gas FG is a mixing ratio (mol%) of CO ₂ : 5.0%, H ₂ : 45%, H ₂ O: 50%, and the flow rate of the raw material gas FG. the 360 cm ³ / min under 25 ° C. · 1 atm, 20 kPa decrease the pressure on the permeate side from the pressure of the feed side, and the flow rate of sweep gas SG and 40 cm ³ / min under 25 ° C. · 1 atm. This experimental condition is common to each example.

According to FIG. 14A, when glutaraldehyde is added, the CO ₂ permeance R _CO2 is slightly lower than when not added. However, as shown in FIG. 14 (b), when glutaraldehyde is added, H ₂ permeance R _H2 is greatly reduced. Therefore, as shown in FIG. 14 (c), by adding glutaraldehyde, It can be seen that the CO ₂ / H ₂ selectivity is greatly increased as compared with the case where it is not added. This is considered to be due to the fact that the addition of glutaraldehyde makes it difficult for film defects to occur due to the formation of a cross-linked structure, resulting in a significant decrease in H ₂ permeance. According to FIGS. 14B and 14C, the H ₂ permeance is lower and the CO ₂ / H ₂ selectivity is higher when 0.008 g of glutaraldehyde is added than when 0.0153 g is added. I understand. That is, the greater the amount of glutaraldehyde added, the higher the selectivity, suggesting that there is an appropriate amount of additive that can achieve high selectivity depending on the experimental conditions.

FIG. 15 shows (a) CO ₂ permeance R _CO2 , (b) H ₂ permeance R _H2 , and (c) CO ₂ / by the membrane of the present invention produced using the cast solution produced by the method of Example 2. of H ₂ selectivity, showing the results of measurement of the feed side pressure in a pressurized state ranging from 200KPa～600kPa. In FIG. 15, each data was measured by varying the amount of glutaraldehyde added when the cast solution was prepared. That is, the experiment was performed with three patterns of (1) 0.008 g, (2) 0.0165 g, and (3) 0 g (no addition) as the amount of glutaraldehyde added. Other experimental conditions are the same as in the case of Example 1.

According to FIG. 15 (a), as in FIG. 14 (a), when glutaraldehyde is added, CO ₂ permeance R _CO2 is slightly lower than when not added. Then, according to FIG. 15 (b), the order similar to FIG. 14 (b), when added to glutaraldehyde _{H 2} permeance _{R H2} is substantially reduced, as shown in FIG. 15 (c), It can be seen that the CO ₂ / H ₂ selectivity is greatly increased by adding glutaraldehyde as compared to the case of not adding it. This is the same reason as in Example 1, that is, the addition of glutaraldehyde caused the H ₂ permeance to be greatly reduced because it was difficult for film defects to occur due to the formation of a crosslinked structure. it is conceivable that. According to FIGS. 15B and 15C, the H ₂ permeance is lower and the CO ₂ / H ₂ selectivity is higher when 0.008 g of glutaraldehyde is added than when 0.0165 g is added. I understand. That is, the greater the amount of glutaraldehyde added, the higher the selectivity, suggesting that there is an appropriate amount of additive that can achieve high selectivity depending on the experimental conditions. In addition, from FIG.15 (c), in the area | region where the gas pressure by the side of a raw material is high, the difference of the selectivity by the addition amount of glutaraldehyde to add is small.

FIG. 16 shows (a) CO ₂ permeance R _CO2 , (b) H ₂ permeance R _H2 , and (c) CO ₂ / by the membrane of the present invention produced using the cast solution produced by the method of Example 3. of H ₂ selectivity, showing the results of measurement of the feed side pressure in a pressurized state ranging from 200KPa～600kPa. In FIG. 15, each data was measured by varying the amount of glutaraldehyde added when the cast solution was prepared. That is, the experiment was performed with four patterns of (1) 0.008 g, (2) 0.0154 g, (3) 0.0343 g, and (4) 0 g (no addition) as the amount of glutaraldehyde added. Other experimental conditions are the same as in the case of Example 1.

According to FIG. 16 (a), as in FIG. 14 (a), when glutaraldehyde is added, CO ₂ permeance R _CO2 is slightly lower than when not added. Then, according to FIG. 16 (b), the order similar to FIG. 14 (b), when added to glutaraldehyde _{H 2} permeance RH ₂ are significantly reduced, as shown in FIG. 16 (c), It can be seen that the CO ₂ / H ₂ selectivity is greatly increased by adding glutaraldehyde as compared to the case of not adding it. This is the same reason as in Example 1, that is, the addition of glutaraldehyde caused the H ₂ permeance to be greatly reduced because it was difficult for film defects to occur due to the formation of a crosslinked structure. it is conceivable that. According to FIG. 16 (b) and (c), towards the case of adding 0.008g of glutaraldehyde, when added 0.0154G, and low _{H 2} permeance than when 0.0343g added, CO ₂ It can be seen that / H ₂ selectivity is high. That is, the greater the amount of glutaraldehyde added, the higher the selectivity, suggesting that there is an appropriate amount of additive that can achieve high selectivity depending on the experimental conditions.

  In FIG. 16C as well, in the region where the gas pressure on the raw material side is high, the difference in selectivity due to the amount of glutaraldehyde added is small.

As described above, referring to the graphs of FIGS. 14 to 16, the gel membrane is cross-linked with glutaraldehyde to suppress a decrease in CO ₂ permeability to a certain extent as compared with the case where glutaraldehyde is not added. However, it is possible to significantly reduce the permeability of H ₂ , and thereby, a facilitated transport membrane exhibiting high CO ₂ / H ₂ selectivity can be realized. In particular, when about 0.008 to 0.015 g of glutaraldehyde is added to 1 g of PVA / PAA copolymer (hereinafter, this range is referred to as “good range”), the selectivity of CO ₂ / H ₂ Is significantly improved.

In addition, the remarkable difference was not looked at by the film | membrane performance between the said Examples 1-3. That is, regardless of which method is used for film formation, it is possible to achieve the effect of improving CO ₂ / H ₂ selectivity by adding glutaraldehyde. In particular, in Examples 2 and 3, even when crosslinked with glutaraldehyde, the decrease in CO ₂ permeance was suppressed. On the other hand, in Example 1, even if the gas pressure on the raw material side was increased, the increase in H ₂ permeance was suppressed to a certain degree.

FIG. 17 is a graph showing long-term performance when glutaraldehyde is added. Specifically, (a) CO ₂ permeance R _CO2 , (b) H ₂ permeance when a long-term experiment was performed using the film prepared by the method of Example 1 (glutaraldehyde addition amount: 0.0339 g) R _H2 and (c) CO ₂ / H ₂ selectivity over time are graphed respectively. The raw material side gas pressure was 401.3 kPa, and other experimental conditions were the same as those shown in FIGS.

  As an experimental method, the membrane of the present invention was set in a permeation cell at about 10 am, the temperature was raised to 160 ° C., a raw material gas and a sweep gas were supplied, and a permeation experiment was started. Under the same conditions until about 8 pm Continued. Then, the supply gas was stopped around 8 pm to lower the temperature to room temperature. The same experiment was conducted again at about 10:00 am the next morning using the same membrane without disassembling the permeation cell. The results of repeating such an experiment for two weeks are shown in FIGS. 17 (a) to 17 (c).

The experimental data in FIG. 17 shows that the amount of added glutaraldehyde is slightly larger than the above-mentioned good range, so the CO ₂ permeance is smaller than the values in FIGS. 14 to 16, but the H ₂ permeance is Even when time elapses, a significantly smaller value is shown than when no glutaraldehyde is added, and the CO ₂ / H ₂ selectivity also maintains a high value of 200 or more. In particular, when performing time-lapse evaluation by repeating startup and shutdown as in this evaluation method, temperature fluctuations (room temperature to 160 ° C.) and pressure fluctuations (normal pressure to 6 atmospheres) are repeatedly given to the membrane. Compared with the case where long-term performance is evaluated by continuing the experiment at the same temperature and pressure, the load on the membrane increases. According to FIG. 17, it can be said that the stability of the film was remarkably improved by adding glutaraldehyde since the film performance was stable for about two weeks even by this evaluation method in which start-up and shutdown were repeated.

Although glutaraldehyde is adopted as a material to be added in the present embodiment, the material addition step is performed to form a crosslinked structure in the film, and any material capable of forming a crosslinked structure is used. For example, it is not limited to glutaraldehyde. In the case of forming a crosslink with an aldehyde group, for example, formaldehyde can also be used. Moreover, even when the material used as the carbon dioxide carrier is a material other than Cs ₂ CO ₃ (for example, Rb ₂ CO ₃ ), it is possible to further improve the membrane performance by introducing an additive in the same manner to obtain a crosslinked structure. It is.

[Third embodiment of the membrane of the present invention]
A third embodiment of the film of the present invention will be described. In addition, this embodiment differs in the shape of this invention film | membrane compared with 1st and 2nd embodiment.

  In the first and second embodiments described above, the description has been made assuming that the facilitated transport film has a flat plate structure as shown in FIG. In contrast, in this embodiment, a facilitated transport film having a cylindrical shape as shown in FIG. 18 is assumed.

FIG. 18 is a schematic view showing the structure of the facilitated transport film of this embodiment. FIG. 19 is a graph showing CO ₂ permeance, H ₂ permeance, and CO ₂ / H ₂ selectivity when a facilitated transport membrane having such a cylindrical shape is used.

18A is a cross-sectional view when cut in parallel to the horizontal plane, and FIG. 18B is a cross-sectional view when cut in the vertical direction on the horizontal plane. The facilitated transport film shown in FIG. 18 has a structure in which a gel film 41 containing a carrier is supported on the outer periphery of a cylindrical hydrophilic ceramic support film 42. In this embodiment, the gel film 41 generated from the same cast solution as that in the first embodiment is used. In other words, Cs ₂ CO ₃ is used as a carrier and thermal crosslinking is performed.

  As shown in FIG. 18, a space 40 is provided between the gel film 41 and the outer frame, and a space 43 is also provided inside the ceramic support film 42.

  When evaluating the membrane performance, the same raw material gas FG as in the above-described embodiment flows into the space 40. On the other hand, an inert sweep gas SG flows into the space 43. A part of the source gas FG that has flowed into the space 40 passes through the gel film 41 (and the support film 42) containing the carrier and flows into the space 43 as a permeable gas PG. An inert sweep gas SG flows into the space 43 in order to exhaust the permeate gas PG out of the system, and an exhaust gas SG ′ in which the sweep gas SG and the permeate gas PG are mixed is shown in FIG. The cooling trap 16 is supplied. The calculation method of permeance and selectivity is the same as that of the first embodiment.

FIG. 19 shows the result obtained when the cylindrical facilitated transport film shown in FIG. 18 is used as the facilitated transport film, the measurement method, the carrier concentration, and the raw material gas pressure are the same as those in FIG. It is a graph based on the obtained data. As in the case of FIG. 10, both CO ₂ permeance and CO ₂ / H ₂ selectivity are high, and the cylindrical facilitated transport membrane having the structure shown in FIG. It turns out that the same effect is shown.

  In the structure shown in FIG. 18, the gel film 41 is exposed in the space 40 so that the gel film 41 directly contacts the source gas FG. That is, compared with the structure shown in FIG. 2, the gel film 41 is not covered with the hydrophobic film. This hydrophobic membrane has the effect of stabilizing the gel membrane and making it difficult to degrade the aging performance. However, as shown in FIG. 20, the facilitated transport film having a cylindrical shape has an effect of improving the aging performance without being covered with a hydrophobic film. This will be described below.

FIG. 20 is a graph comparing long-term performances of a flat type and a cylindrical type facilitated transport membrane, where (a) shows CO ₂ permeance R _CO2 and (b) shows CO ₂ / H ₂ selectivity. In any graph, (1) is cylindrical data, and (2) is flat plate data. The conditions for obtaining the graph result were the same as those in FIG.

  FIG. 20 assumes a structure in which the gel film is not covered with a hydrophobic film as a flat-type facilitated transport film as a comparative example. This is because the cylindrical shape is in a state where one surface of the gel film is exposed to the raw material gas, so that the conditions are common to the flat plate type from the viewpoint of comparison.

According to FIG. 20 (a), with respect to the CO ₂ permeance, the change with time is not so large in both the flat plate type and the cylindrical type. On the other hand, according to FIG. 20B, with respect to the CO ₂ / H ₂ selectivity, in the case of the cylindrical facilitated transport membrane, the performance does not change much over time. In the case of a type facilitated transport membrane, the selectivity decreases with the passage of time, and has dropped to about 10% of the maximum at the end of 100 hours. Accordingly, when the gel film is not covered with the hydrophobic film, it can be seen that the cylindrical-shaped promotion film is superior to the flat plate shape from the viewpoint of long-term performance. On the other hand, it can be seen that, even in the flat plate type, good long-term performance is exhibited by covering the gel film with a hydrophobic film as shown in FIGS.

  The ceramic support film used in this embodiment also has heat resistance of 100 ° C. or higher, mechanical strength, and adhesion to the impregnated gel film, as in the case of the PTFE porous film described in the first embodiment. Is preferred. The porosity (porosity) is preferably 40% or more, and the pore diameter is preferably in the range of 0.1 to 1 μm.

  In the configuration of FIG. 18, the ceramic support film is provided on the inner side and the gel film is provided on the outer side. On the contrary, the support film is formed on the outer side and the gel film is formed on the inner side. Also good. In addition, although described as “cylindrical shape” as a shape, this does not necessarily require that the cross section is an accurate “circle”, and may be an elliptical shape and has some unevenness. It doesn't matter.

According to the present embodiment, it is shown that the long-term performance is improved as compared with the flat plate type by making the promotion film cylindrical. It is considered that this is because the facilitated transport film is hardly deformed and stabilized by making the shape cylindrical. On the other hand, in the case of the flat plate type, the film is deformed with time and defects are generated, and it is considered that the selectivity is lowered by leakage of H ₂ from the defects. That is, in the above embodiment, a ceramic film is used as the support film. However, this film is not limited to ceramics as long as it can be processed into a cylindrical shape and is not easily deformed over time. .

  On the contrary, in the first and second embodiments, the PTFE porous membrane is used as the support membrane. However, if the flat plate state can be stably maintained without being cracked even when the pressure is applied, the PTFE porous membrane can be used. It is not limited to membranes.

[Another embodiment]
Another embodiment will be described below.

<1> In the above-described embodiment, the membrane of the present invention casts a cast solution composed of an aqueous solution containing a PVA / PAA copolymer and carbon dioxide carrier Cs ₂ CO ₃ into a hydrophilic PTFE porous membrane for supporting a gel membrane. Although it was prepared by gelation later, the membrane of the present invention may be manufactured by a manufacturing method other than the manufacturing method. For example, the PVA / PAA copolymer gel film may be prepared by later impregnating a Cs ₂ CO ₃ aqueous solution.

<2> In the first embodiment, the case where a CO ₂ facilitated transport film is manufactured by adding cesium carbonate as an additive to the gel film has been described. An effect can be obtained. This is because the reaction shown in the above (Chemical Formula 3) occurs by using the gel membrane to which cesium hydroxide is added for CO ₂ separation, thereby converting cesium hydroxide into cesium carbonate. Furthermore, it can be seen that the same effect can be obtained from the above (Chemical Formula 3) when cesium bicarbonate is used instead of cesium carbonate.

Incidentally, the case where by the rubidium carbonate was added to the gel film as an additive for producing a CO ₂ -facilitated transport membrane also similarly be used rubidium hydroxide or bicarbonate rubidium in place of rubidium carbonate.

  <3> In the above embodiment, the membrane of the present invention has a three-layer structure composed of a hydrophobic PTFE porous membrane / gel layer (impregnated gel membrane supported on a hydrophilic PTFE porous membrane) / hydrophobic PTFE porous membrane. The support structure for the membrane of the present invention is not necessarily limited to the three-layer structure. For example, a two-layer structure composed of a hydrophobic PTFE porous membrane / gel layer (an impregnated gel membrane supported on a hydrophilic PTFE porous membrane) may be used.

<4> The mixing ratio of each component in the composition of the film of the present invention exemplified in the above embodiment, the dimensions of each part of the film, etc. are examples for easy understanding of the present invention. It is not limited to a CO ₂ facilitated transport membrane.

The carbon dioxide separator according to the present invention can be used for carbon dioxide separation, and in particular, can separate carbon dioxide contained in reformed gas for fuel cells, etc. containing hydrogen as a main component at a high selection ratio with respect to hydrogen. It is useful for a CO ₂ permeable membrane reactor equipped with a simple CO ₂ facilitated transport membrane.

1: PVA / PAA gel film (gel layer) containing carbon dioxide carrier
2: Hydrophilic porous membrane 3, 4: Hydrophobic porous membrane 10: CO ₂ facilitated transport membrane (sample)
11: Flow-type gas permeation cell 12: Raw material side chamber 13: Permeation side chamber 14, 16: Cooling trap 15: Back pressure regulator 17: Gas chromatograph 18: Metering liquid pump 19: Back pressure regulator 20: CO transformer (CO ₍₂ permeation type membrane reactor)
21: Sweep gas passage 40: Space 41: Gel membrane 42: Ceramic support membrane 43: Space FG: Source gas FG ': Treated gas PG: Permeated gas SG, SG': Sweep gas

Claims (9)

A source gas containing at least hydrogen, carbon dioxide, and water vapor is supplied to the raw material side surface of the CO ₂ facilitated transport membrane at a supply temperature of 100 ° C. or more, and the carbon dioxide that has permeated the CO ₂ facilitated transport membrane is taken out from the permeate side surface. A carbon separator,
The CO ₂ facilitated transport film is formed by supporting a gel layer obtained by adding an additive composed of cesium carbonate, cesium bicarbonate or cesium hydroxide on a polyvinyl alcohol-polyacrylic acid copolymer gel film on a hydrophilic porous film. The carbon dioxide separator characterized by the above-mentioned.   The gel layer is configured such that a weight ratio of cesium carbonate to a total weight of the polyvinyl alcohol-polyacrylic acid copolymer gel film and cesium carbonate is in a range of 65 wt% to 85 wt%. 2. The carbon dioxide separator according to 1. A source gas containing at least hydrogen, carbon dioxide, and water vapor is supplied to the raw material side surface of the CO ₂ facilitated transport membrane at a supply temperature of 100 ° C. or more, and the carbon dioxide that has permeated the CO ₂ facilitated transport membrane is taken out from the permeate side surface. A carbon separator,
The CO ₂ facilitated transport film is formed by supporting a gel layer obtained by adding an additive composed of rubidium carbonate, rubidium bicarbonate or rubidium hydroxide on a polyvinyl alcohol-polyacrylic acid copolymer gel film on a hydrophilic porous film. The carbon dioxide separator characterized by the above-mentioned.   The carbon dioxide separator according to any one of claims 1 to 3, wherein the gel layer supported on the hydrophilic porous membrane is covered with a hydrophobic porous membrane.   The carbon dioxide separator according to any one of claims 1 to 4, wherein the gel layer has a cross-linked structure derived from an aldehyde group.   The carbon dioxide separator according to any one of claims 1 to 5, wherein the porous membrane has heat resistance of 100 ° C or higher.   The gel layer and the hydrophilic porous membrane both have a cylindrical shape with the same axial center, and one membrane has its inner surface in contact with the outer surface of the other membrane, and the other membrane. The carbon dioxide separator according to any one of claims 1 to 3, wherein the carbon dioxide separator is configured to surround.   The carbon dioxide separator according to claim 7, wherein the hydrophilic porous membrane is a ceramic porous membrane. The carbon dioxide separator according to claim 7 or 8, wherein the gel layer is formed outside the hydrophilic porous membrane so as to surround the hydrophilic porous membrane.

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