JPH0254134B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a selectively permeable membrane for gas. More specifically, the present invention relates to a gas selective permeation membrane suitable for the permeation of gases, particularly carbon monoxide, in which a specific reaction product is retained either alone or as a solution on a membrane serving as a support. [Prior Art] Various polymer membranes are conventionally known as separation membranes for gas mixtures, but these membranes have relatively low gas permeability coefficients, and materials with higher permeability coefficients are desired. When the membrane is liquid, the gas diffusion coefficient generally increases, and therefore the permeability coefficient can be increased. Furthermore, when such a liquid membrane contains a substance that selectively and reversibly interacts only with a certain gas, it is possible to further increase the permeability of that gas. On the other hand, the selective performance of a membrane is given by the difference in the solubility of gases in the membrane and the difference in the rate of diffusion of gases in the membrane, so it selectively and reversibly interacts only with the above-mentioned specific gases. When a substance is included in the membrane, the solubility of only that gas increases, and the selectivity can be dramatically increased. Many examples are known of membranes containing substances that selectively and reversibly interact only with certain gases, such as the separation of carbon dioxide gas using an aqueous solution of alkali metal bicarbonate (Special Publication No. 45). −
1176), Separation of olefins using an aqueous solution of silver nitrate (Special Publication No. 53-31842), Separation of nitric oxide using a formamide solution of ferrous chloride (AI Ch E
Journal vol 16 No. 3 405 pages 1970), and these liquid membranes are used by being held on a membrane that serves as a support. Furthermore, for the separation of carbon monoxide, an aqueous solution of copper chloride in hydrochloric acid is known, but this method has the disadvantage that a concentrated aqueous solution of hydrochloric acid must be used. Further, when the pressure is reduced in the secondary case of permeation (outflow side), there is a problem that water vapor and hydrogen chloride gas permeate and become mixed with other gases. [Problems to be Solved by the Invention] The present inventors have studied substances that have selective reversible interactions with certain gases, particularly substances that have selective reversible interactions with carbon monoxide. As a result, a membrane retaining the reaction product of an inorganic copper compound and 1,2,4-triazole or 3,5-dimethylpyrazole significantly promoted the permeation of carbon monoxide and achieved extremely high carbon monoxide selective separation performance. It was discovered that carbon monoxide exhibits a high permeation rate, and the present invention was achieved. [Means for solving the problem] That is, the gist of the present invention is to provide an inorganic copper compound and 1.
It is a gas selective permeation membrane in which a reaction product with 2,4-triazole or 3,5-dimethylpyrazole is retained on a membrane serving as a support. The present invention will be explained in detail below. The inorganic copper compound used in the present invention is described in Kagaku Daijiten (published by Kyoritsu Shuppan Co., Ltd. in 1960), Volume 9.
Means a compound containing copper among the inorganic compounds described in the section of "Peeling baskets" on page 57,
Examples of such inorganic copper compounds include, but are not limited to, cuprous chloride, cupric chloride, cuprous oxide, cupric oxide, cuprous bromide, cupric bromide, and cuprous cyanide.
Examples include copper, cupric cyanide, copper thiocyanate, copper fluoride, copper iodide, copper sulfide, copper sulfate, etc.
These can be used alone or as a mixture. Among these, cuprous iodide, cuprous thiocyanate,
Copper, cuprous chloride, and the like are particularly suitable inorganic copper compounds. If the inorganic copper compound, 1,2,4-triazole or 3,5-dimethylpyrazole is a commercially available product,
It may be used as is or may be further purified. 1,2,4-triazole or 3,5-dimethylpyrazole is preferably used in the form of a solution or slurry using a solvent. In this case as well, the higher the solubility in the solvent, the more advantageous it is to facilitated transport. As solvents, ketones, esters, ethers, alcohols, amines, amides, other nitrogen-containing compounds,
Sulfur-containing compounds, phosphorus-containing compounds, and halogen-containing compounds can be used. acetone, ethyl acetate,
Acetonitrile, methanol, ethanol, etc. are suitable in that they dissolve 1,2,4-triazole or 3,5-dimethylpyrazole well, but when reducing the pressure on the secondary side of permeation, these compounds have a low vapor pressure. Because of its high gas content, it has the disadvantage that it passes through as vapor and mixes with other gases.
In this case, it is desirable to carry out the process at below freezing temperature. On the other hand, when using a solvent with relatively low vapor pressure, such as acetophenone, N-methyl 2-pyrrolidone, γ-butyrolactone, ethylene glycol, tetraethylene glycol dimethyl ester, polyethylene glycol, glycerin, dimethyl sulfoxide, benzonitrile, etc. , room temperature is sufficient. When carrying out the reaction at a higher temperature, benzophenone, which is solid at room temperature, can be used as a solvent. When the inorganic copper compound and 1,2,4-triazole or 3,5-dimethylpyrazole are liquid, the ratio is usually 1,2,4-triazole or 3,5-dimethylpyrazole/copper compound>
0.1 (molar ratio) or more is selected, but in order to provide high permeability and high selectivity, 0.1<1,2,4-triazole or 3,5-dimethylpyrazole/inorganic copper compound<100 (molar ratio) is desirable, and 0.5<1,
2,4-triazole or 3,5-dimethylpyrazole/inorganic copper compound <50 (molar ratio) is particularly preferred. The ratio of 1,2,4-triazole or 3,5-dimethylpyrazole to the solvent is usually 1,2,4-triazole or 3,5-dimethylpyrazole/
Solvent>0.001 or more is selected. The reaction temperature can generally be 0 to 200°C, and it is preferable to carry out the reaction under an inert gas stream. When a solvent is used, it is desirable to dissolve 1,2,4-triazole or 3,5-dimethylpyrazole in the solvent and then add the inorganic copper compound. Alternatively, the solid content (reaction product) may be taken out by a method such as reduced pressure or precipitation, and then dissolved in a solvent that can dissolve it again. Next, the inorganic copper compound thus obtained and 1,2,
The support used for holding the reaction product with 4-triazole or 3,5-dimethylpyrazole is not particularly limited as long as it is a membrane having gas permeable properties. Furthermore, the holding method is not particularly limited as long as the holding allows selective permeation of gases, particularly carbon monoxide, but for example, these reaction products in liquid form or dissolved in a solvent A method in which a reaction product solution is filled into the pores of a porous support, a method in which it is embedded in a crosslinkable polymer network formed on a support membrane, and a method in which a solution of a reaction product is embedded in a cross-linked polymer network formed on a support membrane, Examples include a method of retaining it as a liquid film, a method of retaining it in arranged molecules formed on a support, and the like. The type of membrane material used as the support is not particularly limited, but includes regenerated cellulose, cellulose ester, polycarbonate, polyester, Teflon, nylon, acetyl cellulose, polyacrylonitrile, polyvinyl alcohol, polymethyl methacrylate, polysulfone, polyethylene, polypropylene. , polyvinylpyridine, polyphenylene oxide, polyphenylene oxide sulfonic acid, polybenzimidazole, polyimidapyrrolone, polypiperazine amide, polystyrene, polyamino acid, polyurethane, polyamino acid polyurethane copolymer, polysiloxane, polysiloxane polycarbonate copolymer Organic polymers such as coalescence, polytrimethylvinylsilane, collagen, polyion complexes, polyurea, polyamide, polyimide, polyamideimide, polyvinyl chloride, and sulfonated polyfurfuryl alcohol; inorganic materials such as glass, alumina, silica, silica alumina, carbon, and metals. Substances can be given. These supports can be used in any of the shapes of a flat plate, a tube, a spiral, and a hollow fiber. These supports may be entirely porous, may be an anisotropic film having a dense layer only on the surface, or may be a homogeneous film. Alternatively, the surface may be coated with a thin film of another material by a method such as vapor deposition, coating, or polymerization. The overall thickness is not particularly limited, but is preferably in the range of 10 to 1000μ. Such a support can also be used by being superimposed on a support made of another material. The layer of the reaction product of the inorganic copper compound and 1,2,4-triazole or 3,5-dimethylpyrazole held on these supports can have a thickness of several angstroms or more, Not particularly limited. However, if the liquid film of these reaction products is used without stirring,
The thinner the thickness, the more preferable it is in order to obtain a higher transmission rate. In addition, if it is too thin, the permeation rate of gases other than those intended for separation will increase, resulting in a decrease in separability, which is not preferable. The most suitable film thickness varies depending on the rate constants of binding and dissociation between the gas and these reaction products, the equilibrium constant, and other conditions, but is approximately 0.01~
It is used at a film thickness of 50,000μ, more preferably 0.1 to 10,000μ. In addition, when using a liquid film under stirring,
Although there is no problem even if the film is thick, it is preferable that the substantial film thickness existing as a diffusion layer on the surface of the support film is the same as the film thickness in the case of no stirring. Various methods can be used to separate gases using a membrane in which the reaction product of an inorganic copper compound and 1,2,4-triazole or 3,5-dimethylpyrazole is supported on a support. When gases are separated using a polymer film, a partial pressure difference between the gases to be separated is applied to both sides of the membrane. In addition, apart from the membrane cell, an inorganic copper compound and 1,
A container containing the reaction product or its solution with 2,4-triazole or 3,5-dimethylpyrazole is placed, and a pump is used to guide this liquid to the surface of the support membrane (primary side of the membrane) of the membrane cell. A circular method can also be used. In this case, carbon monoxide, for example, is sufficiently absorbed into the liquid in a reservoir container, and the dissolved or combined gas is continuously removed by reducing the pressure on the secondary side of the membrane in the membrane cell. Carbon monoxide is extracted continuously and highly selectively by dissociating and desorbing it, leading it to the secondary side of the membrane, leading the liquid that has lost carbon monoxide to a reservoir, and dissolving carbon monoxide again. You can also use the method In this case, the temperatures of the membrane cell and the reservoir can be made different to facilitate the extraction of carbon monoxide. Although the temperature of the membrane cell portion is not particularly limited, it can be used, for example, in the range of 0 to 200°C. Another method of supporting the reaction product of an inorganic copper compound and 1,2,4-triazole or 3,5-dimethylpyrazole or its solution on a membrane serving as a support is to apply the above reaction to the pores of a porous support. Possible methods include a method of filling the product or its solution, and a method of dissolving or dispersing the reaction product or its solution in a nonporous membrane of the support and retaining the solution. The method of retaining the reaction product includes a method of dissolving or dispersing it in a component having regularly arranged molecules such as liquid crystal. [Effects of the Invention] The gas separation membrane thus obtained can be advantageously used mainly for separating carbon monoxide. For example, it mainly consists of synthetic gas obtained by steam reforming or partial oxidation of hydrocarbons such as natural gas, light naphtha, and heavy oil, and mixed gas containing carbon monoxide obtained as a byproduct gas of coal gasification and steel manufacturing. Carbon monoxide can be separated in high yield and used as a raw material for various chemical reactions. [Example] Next, the present invention will be explained with reference to an example. Example 1 3.10 g of 1,2,4-triazole (commercially available product used as is) was placed in a flask under a stream of dry nitrogen, and 15 ml of N-methylpyrrolidone (commercially available product, dehydrated and deoxidized) was added thereto. , stirred.
After a while, the solution became homogeneous. To this was added 1.82 g of cuprous thiocyanate (a commercially available product was used as is) and the mixture was stirred. After a while, the solution became almost homogeneous. On the other hand, an asymmetric membrane of polytrimethylvinylsilane was attached to the cell for gas permeation measurement, and the skin layer side was set as the primary side. The nitrogen permeation rate of this membrane is 9.0×10 ^-5
cm ³ /cm ²・sec・cmHg. The above homogeneous solution is poured onto this membrane under a stream of inert gas.
12.5 ml was added and stirred. After reducing the pressure on both the primary and secondary sides, a gas of 1 kg/cm ² was passed through the primary side, and the secondary side was evacuated, and the permeability of various gases was measured by gas chromatography. Pure gas was used as the measurement gas. The results are shown in Table-1. As can be seen from the table, the permeability of carbon monoxide is extremely large compared to other gases.
It can be seen that the permeation of only carbon monoxide gas was selectively promoted. Furthermore, this method has the advantage that not a single droplet of N-methylimidazole passes through to the secondary side during the experimental operation, and since the vapor pressure of N-methylimidazole is low, its vapor also does not pass through. (I experimented with a trap tube attached, but not a single drop was collected.) Comparative example 1 1,2,4-triazole and thiocyanic acid No. 1
The permeation rates of various fluids were measured in the same manner as in Example 1, using only 12.5 ml of N-methylpyrrolidone instead of the solution of the reaction product with copper. Table 1 shows the results.
Shown below. Example 2 3,5 instead of 1,2,4-triazole
The permeation rates of various gases were measured in the same manner as in Example 1, except that 4.32 g of -dimethylpyrazole was used. The nitrogen permeation rate of the polytrimethylvinylsilane membrane used was 3.72×10 ⁻⁴ cm ³ /cm ² ·sec·cmHg. Comparative Examples 2 and 3 Copper iodide () or copper chloride () and 3,5
The permeation rate of various gases was similarly measured according to the method of Example 1 using the reaction product with -dimethyl-1-allylpyrazole. The results are shown in Table-1.

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Claims (1)

[Claims] 1 Carbon monoxide separation held on a support membrane formed from a reaction product of an inorganic copper compound and 1,2,4-triazole or 3,5-dimethylpyrazole by a membrane-forming method that does not involve plasma polymerization. Gas selective permeation membrane for use.