JPS63194716A - Gas selective separating material - Google Patents

Abstract

PURPOSE:To efficiently recover CO or the like, by mixing copper compd. with ascorbic acids in a solvent and using the mixture as an absorbent and a separating material of gas such as a permeable membrane. CONSTITUTION:Copper compd. such as Cu(NO3)2, Cu(CH3CO2)2, CuF2, CuI2 and Cu(BF4)2 is mixed with ascorbic acids such as L-ascorbic acid in the solvent incorporating N-contg. heterocyclic compd. such as N-methylimidazole. This mixture is used as the absorbent or a gas permeable membrane held with it on a supporting membrane and thereby CO is recovered with high yield from CO-contg. gas by selectively absorbing CO or selectively permeating CO.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a selective gas separation material useful for gas separation.

Specifically, the present invention relates to a gas selective separation material obtained by mixing a copper compound and ascorbic acid or a derivative thereof in a solvent, particularly a solvent containing a nitrogen-containing heterocyclic compound.

[Conventional technology]

Removal of carbon monoxide from gases produced by steam reforming or partial oxidation of hydrocarbons such as natural gas, light naphtha, and heavy oil, and from steelmaking byproduct gases such as converter gas, blast furnace gas, and coke oven gas. Separation technology useful for concentration and purification has become an important technology in the chemical industry, such as the purification of raw material gas in ammonia synthesis and the production of raw materials for synthesis of various chemical industry products.

Methods for separating and concentrating carbon monoxide from a gas mixture containing it include a cryogenic separation method, an absorption liquid method, an adsorption method, and an agricultural method, but each method has its own technical problems.

The cryogenic separation method consists of a complex refrigeration and heat recovery system, and because the operating temperature is low, it is necessary to use high-grade materials for the equipment, which reduces construction costs. Furthermore, power consumption increases due to low temperature operation. Furthermore, in order to prevent blockage accidents within the equipment, it is necessary to install pretreatment equipment to completely remove impurities from the gas.

As for the absorption liquid method, the method of using hydrochloric acid acidic chloride aqueous solution or ammoniacal cuprous aqueous solution as an absorption liquid for hydride carbon has been practiced for a long time, but the absorption liquid has strong corrosivity and deposits. There were drawbacks such as the production of large amounts of water and the high construction costs. In recent years, an absorption liquid method called the ○08ORB process in which a toluene solution of copper aluminum chloride is used as an absorption liquid for carbon monoxide has been developed and put into practical use. This method has the advantage that impurities in the gas, especially carbon dioxide, which needs to be removed by pretreatment in the above method, are not absorbed, so that the separated carbon monoxide is of high purity.

However, when it comes into contact with a mixed gas containing water, hydrogen sulfide, ammonia, etc., the copper chloride/aluminum chloride complex in the absorbent reacts irreversibly with these impurities, inhibiting the absorbent's ability to absorb carbon monoxide. Ru. Also, heating is required to remove carbon monoxide from the absorption liquid.

Regarding adsorption methods, an adsorption method using zeolite as an adsorbent has recently been developed, and practical equipment has started operating for converter gas and the like. This method allows operation at room temperature and small-scale equipment, and compared to the conventional absorption liquid method, there is no problem of solvent evaporation and stable contact operation can be obtained. It is good when the difference in properties is small and the concentration of carbon monoxide in the gas is high, such as in converter gas, but when the concentration of carbon monoxide is low, it may be difficult to obtain high-purity carbon monoxide in one step. Conceivable. Also, in the case of zeolite,
Since carbon dioxide (carbon monoxide) is more easily adsorbed, it is necessary to remove it in the first stage. Furthermore, it is safe to perform adsorption under pressure and desorption under reduced pressure, but the power cost increases.

Finally, regarding membrane properties, q! The polymer membrane of R building is being studied.

However, when using only these ordinary polymer membranes, carbon monoxide has low permeability compared to other gases such as hydrogen. Therefore, for example, this is a practically useful method when used for the purpose of separating hydrogen from a gas mixture that contains excess hydrogen by permeating it through a membrane and changing the mixing ratio of hydrogen and carbon monoxide in the fIA gas. The purpose of the trap is to obtain high concentrations of carbon monoxide.

Selectivity is low and cannot be applied.

A polymer membrane has a small gas permeability coefficient, but when the membrane is liquid, the gas solubility coefficient and diffusion coefficient are large, so the permeation coefficient can be increased. Furthermore, if 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 mutual solubility of gases in the membrane and the difference in the diffusion rate of gases in a narrow width. When it is included in a narrow width, the solubility of only that gas becomes extremely high; the xb selectivity can also be dramatically increased.

Many examples are known of such membranes containing substances that selectively and reversibly interact only with certain gases. (Special Publication Sho/If-1776), Separation of Olefins Using Silver Nitrate Aqueous Solution (Special Publication Sho J 3-3/?
4tλ Publication 9, Separation of Nitric Oxide by Formamide Solution of Ferrous Chloride (A, Engineering Oh Ff, Tourna
l vol / 44 j4tor page / 97θ year)
However, in these cases, water vapor and hydrogen chloride gas permeate through the gas, creating a problem if they mix with other gases.

As mentioned above, various methods of separating carbon monoxide have been developed, but each has its own advantages and disadvantages, and improvements in these problems are desired.

[Problem that the invention seeks to solve]

The present inventors have discovered that carbon monoxide has excellent selective absorption and separation performance, is capable of absorption and desorption at room temperature, does not reduce its absorption capacity for carbon monoxide even when it comes into contact with impurities such as water and oxygen, and is corrosion-resistant. We have carried out research with the aim of developing substances that are useful as gas selective absorption liquids using neutral, chemically mild, and inexpensively available reagents, and gas selective permeation membranes using such substances. We have developed a selective separation material.

[Failure to solve the problem]

Next, the content of the present invention will be explained in detail.

The present invention relates to reaction mixtures useful in gas separation. Specifically, the present invention relates to a gas selective separation material obtained by mixing a copper compound and ascorbic acid or a derivative thereof in a solvent, particularly a solvent containing a nitrogen-containing heterocyclic compound.

The gas selective separation material of the present invention is particularly effective for the separation and purification of carbon monoxide among gases, but it is also effective for the separation and purification of olefins,
It is also thought to be effective in separating and removing oxygen.

First, the copper compound used as a component of the highly selective gas separation material of the present invention will be explained. Conventional carbon monoxide absorption liquids mainly used monovalent copper salts, but the present invention uses not only monovalent copper salts but also divalent copper salts as well as monovalent copper salts. As mentioned above, an important feature is that it can be effectively used as a starting material. The copper compound used is limited to %L
Naica HAOU1'80HKMIOAL D-work OT work 0
NARY4t th Edition (MaGRA
W-H Engineering LL BOOK OOMPANY) &-4t
7-4t-g? Copper compounds and HANDBOO listed on the page
K of OHEM Engineering STR'! and PHYS Engineering 08J-7th Edition (OROPRB8S
) B-709 to B- // Copper compounds described on page 2 are exemplified. Special copper compounds include cuprous chloride, cupric chloride, cuprous bromide, steel bromide, cuprous iodide, cuprous fluoride, cupric fluoride, and thiocyanide. cupric acid, cupric thiocyanate, cupric cyanide, cupric cyanide, cupric hydroxide, cupric perchlorate, cupric perchlorate, cupric periodate, Cupric carbonate, cupric sulfate, class 2 nitrate, cupric phosphate, cupric tungstate, cupric borofluoride, copper salts of various organic acids such as cupric formate, cupric acetate Copper, cupric propionate, cupric oxalate, cupric tartrate, cupric citrate, cupric benzoate, cupric palmitate, cupric lauryl mi, cupric salicylate, cupric oleate di-copper,
cupric stearate, cupric acetylacetone, glycerin derivatives and hydrates of the above copper compounds, coordination compounds of ammonia, amines, pyridines and imidazoles,
Further examples include oxides produced by the reaction of the above-mentioned copper compounds with oxygen, etc., and these may be used alone or in combination.

It shows a compound represented by the following, and also includes a mixture of 9-form, L-form, and DL-form. Specific examples include L-ascorbic acid, L-ascorbyl stearade, L-ascorbyl palmitate, L-ascorbyl civalmitate, potassium L-ascorbate, and sodium L-ascorbate. These may be used alone or in combination.

The ratio of ascorbic acid or its derivative to the copper compound is not particularly limited, but if the ratio of ascorbic acid or its derivative to the copper compound is small, the carbon monoxide absorption of the gas selective separation material will be affected by the ascorbic acid or the copper compound. The derivative O0/mol to 10 mol, preferably O0! Mol~!
A molar range is chosen, most preferably between 7 mol and 3 mol.

Finally, the solvent used to dissolve and react the copper compound of the present invention and ascorbic acid or its derivative will be described. As the solvent, any compound that can dissolve the copper compound and ascorbic acid or the solvent may be used. However, nitrogen-containing heterocyclic compounds such as imidazoles and pyridines, or polyalkyleneboryanines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, heptaethyleneoctamine, and nonaethylenedecamine are preferably used alone or in combination with other compounds. It is used in combination with a solvent.

Large organic chemistry as imidazoles (breakfast bookstore, Showa 4t)
2 years) / Vol. J / 73 Negative ~ The compounds described on page 2!7 are listed as pyridines from Vol. 4, page 2 of the same document, and the compounds described on page 2 are listed as ethylenediamines, Vol. 4 of the same document, p. 2 j
The compounds described on page r2, the above-mentioned idazoles, pyridines,
The solvent that can be used with ethylenediamines may be any solvent that can dissolve these compounds, copper compounds, ascorbic acid or derivatives thereof well, has a high boiling point, and has a low vapor pressure at room temperature, such as ketones, Esters, ethers, alcohols, amines, amides and other nitrogen-containing compounds, sulfur-containing compounds, phosphorus-containing compounds, and nitrogen-containing compounds can be used, and even if these are used alone,
May be used in combination. Examples of suitable solvents include dimethylsulfoxide, dimethylformamide, dimethylacetamide, and the like.

The ratio of the copper compound to these solvents is not particularly limited, but is usually 0. /~3 molar concentration range. Although it is desirable that the resulting solution be a homogeneous solution, it can also be used in the form of a slurry containing insoluble matter. The volume ratio of imidazoles, pyridines, and ethylenediamines in the above solvent to the entire solvent can be arbitrarily selected within the range of O2/θ0 to 10Q:θ. The temperature at which the copper compound and ascorbic acid or its derivatives are mixed in a solvent is not particularly limited, but is usually in the range of θ to 200°C, and is preferably carried out under an inert gas stream.

Next, a method for separating a specific gas, particularly carbon monoxide, using a reaction mixture obtained by mixing a copper compound and ascorbic acid or a derivative thereof in a solvent will be explained.

The first method is to bring a gas mixture into contact with a solution containing the reaction mixture, selectively absorb a specific gas, especially carbon monoxide, and then change the pressure and/or temperature to absorb the absorbed gas. By repeating the releasing operation, certain gases, especially carbon monoxide, can be separated. In this case, the pressure at which the reaction mixture absorbs the gas may be any pressure higher than zero, but in order to increase the selectivity, a low pressure of 7 atm or less is used, and in order to increase the rate of gas absorption, the pressure is lower than /atm. It is preferable to carry out the process at a pressure above the barrel pressure. Normal Q~
It is carried out at a pressure of 10 atm, preferably θ,/~3 atm.

Further, in order to release the gas once absorbed at room temperature, it is usually carried out under reduced pressure. / At any pressure below atmospheric pressure,
In order to increase the rate of gas discharge, it is desirable to have as low a pressure as possible, and in order to reduce power consumption, it is desirable to have a high pressure.

It is usually carried out at a pressure of θ~/atm, preferably θ/~0.1 atm. There is no particular limit to the temperature at which gas is absorbed, but it is easier to absorb gas at a low temperature, so the temperature is preferably below 0°C! A temperature below θ°C is adopted. There is also no particular restriction on the temperature at which the gas is released, but in this case, both temperatures are preferred in terms of increasing the release rate. Usually, a temperature of room temperature or higher, preferably from jO<0>C to 300<0>C is employed. When gas is released at high temperatures like this, it is not necessarily necessary to perform the process under reduced pressure; actual flow can also be performed at pressures higher than atmospheric pressure. Of course, absorption and release can be carried out under both pressure and temperature conditions; in this case, it is preferable to absorb at low temperature and high pressure and release at high temperature and low pressure.

The second method in history is to mix a copper compound and perilla or its derivatives in a solvent, hold the reaction mixture on a membrane that serves as a support, and select a specific gas, especially carbon monoxide, from the mixed gas. It is possible to selectively separate certain gases, especially carbon monoxide, by absorbing the gas on the other side of the membrane, lowering the pressure, and permeating the membrane. In this case, the support used to hold the reaction mixture is not particularly limited as long as it is a membrane that is permeable to gas.

The holding method is not particularly limited as long as the holding allows selective permeation of gases, especially carbon monoxide; Examples include a method of holding as a film, and a method of holding by dissolving or dispersing in aligned molecules such as liquid crystal formed on a support.

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, polyimidazopyrrolone, polybibe didine amide, polystyrene, polyacinoic acid, polyurethane, polyamino acid polyurethane copolymer, polysiloxane, polysiloxane polycarbonate copolymer organic polymers such as polytrimethylvinylsilane, collagen, polyion complexes, polyurea, boria, polyimide, polyamideimide, polyvinyl chloride, sulfonated polyfurfuryl alcohol, glass,
Inorganic materials such as aluminum, silica, silica alkali, carbon, and metals can be used.

The shape of these supports may be flat, tubular, spiral, or hollow fiber.

These supports may be entirely porous. The overall thickness is not particularly limited, but is preferably in the range of 10 to /θ00μ. Such a support can also be used by being superimposed on a support made of another material.

The thickness of the reaction mixture 11111 obtained by mixing the copper compound held on these supports and ascorbic acid or its derivative in a solvent is not particularly limited, and can be used at a thickness of several angstroms or more. However, when the liquid film of these reaction mixtures is used without stirring, the thickness should be approximately 0.0 mm, depending on the number, equilibrium constant, and other conditions, in order to obtain a higher permeation rate as the thinner the film is.
0~50000μ, more preferably 0. /~1ooo
It is used with a film thickness of oμ. In addition, when using a liquid film under stirring, there is no problem even if the film thickness is as thick as 70°, but the actual film thickness that exists as a diffusion layer on the surface of the support film is the same as the film thickness without stirring. Preferably, they are the same.

Various methods can be used to separate gases, but one method involves separating a reaction mixture obtained by mixing a copper compound and ascorbic acid or its derivatives in a solvent onto both sides of the membrane using a membrane holding the reaction mixture on a support. Alternatively, a container containing the reaction mixture solution is placed separately from the membrane cell, and a pump is used to pump this liquid onto the surface of the membrane cell's support membrane (the primary layer of the membrane). It is possible to use a method in which the material is guided to the side (side) and circulated. In the latter case, the reaction mixture solution, which has absorbed carbon monoxide, for example, at the membrane surface, is introduced into a separate container;
For example, carbon monoxide can be released under reduced pressure, or conversely, carbon monoxide can be absorbed into a liquid in a reservoir.
By reducing the pressure on the primary side of the membrane in the membrane cell, the dissolved or combined gas is continuously dissociated and desorbed and guided to the secondary side of the membrane, and the liquid that has lost carbon monoxide is guided to the reservoir. It is also possible to dissolve carbon monoxide again. In this case, the temperatures of the membrane cell and the reservoir can be made different to facilitate the extraction of carbon monoxide. The temperature of the membrane cell part is, for example, O
Can be used in the range of -100℃.

As a third method, the nuclear reaction mixture can also be retained on a particulate carrier. The same material as the support membrane can be used as the carrier.

〔Example〕

Next, the present invention will be explained by examples.

Comparative Example/~J Prepare a three-way cock and a three-way eggplant-shaped flask (inner volume of the space closed by the cock is 9-9), connect the three-way cock to a gas burette, and use the three-way cock as a vacuum pump. and a nitrogen supply twin. A vacuum pump and a carbon monoxide supply line were also connected to the gas buret.

A Teflon rotor and the copper compounds listed in Table 1 were added to the above eggplant-shaped flask, and after the inside of the flask was replaced with nitrogen, N-methylimidazole and 2yd were added and mixed under stirring for 7 hours. .

In Comparative Example /, the copper compound was dissolved in tl, but in Comparative Example =, some of the copper compound remained insoluble, and in Comparative Example 3, a considerable amount of the copper compound remained insoluble.

The inside of the eggplant-shaped flask containing the homogeneous solution obtained by mixing the copper compound and N-methylimidazole was degassed using a vacuum pump, and carbon monoxide was introduced from a gas burette while stirring to cause monoxide at -0°C. The amount of carbon absorbed was measured over time. At this time, the Teflon rotor, copper compound, and N
- The amount of carbon monoxide required to fill the space excluding the volume of methylimidazole was subtracted from the amount of change in the gas burette to calculate the actual amount of absorbed carbon monoxide.

As shown in the results in Table 1, the copper compound-N-methylimidazole mixture did not exhibit carbon monoxide absorption ability for any of the copper compounds of Comparative Examples 1 to 3.

Example/~! The amount of absorbed carbon oxide was measured over time.

Predetermined amounts of copper compound eyelids, L-7 scorbic acid, and other compounds listed in Table λ were mixed with Comparative Examples/~3 and left overnight. For each composition of the carbon monoxide absorption solution, the saturated absorption amount of carbon monoxide and the number of moles of the carbon monoxide absorption solution containing 7 moles of copper compound are shown in the figure.

Reference Example/Comparative Example/A Teflon rotor was placed in an eggplant-shaped flask having an inner volume of data used in ~3, and after purging the inside with nitrogen, commimole of cuprous iodide and N-methylimidazole were added. After stirring and mixing for about one hour, the mixture was degassed using a vacuum pump, and the amount of carbon monoxide absorbed was measured using the same apparatus and method as in Comparative Examples/--3. The result was 0.16 (per mole of cuprous iodide)
A molar equivalent carbon monoxide uptake was obtained.

Comparative Example In the same manner as in Reference Example, cuprous iodide, 2-barimole, and N-methylimidazole, 2- were added and mixed with stirring under a nitrogen atmosphere for about one hour. Next, the inside of the flask was once degassed using a vacuum pump, and then oxygen was introduced to restore the pressure to normal pressure. In this state/
After stirring for a period of time, the mixture was degassed using a vacuum pump, and the amount of carbon monoxide absorbed was measured using the same apparatus and method as in Comparative Examples/--3.

As a result, only 1 mole of copper iodide and 73 moles of carbon monoxide were absorbed. A comparison with Reference Example 1 shows that the carbon monoxide absorption capacity of the reaction mixture of cuprous iodide and N-methylimidazole is reduced by contact with oxygen.

Example: cuprous iodide, mmol, N-methyl, dazol 2 tl
d! Towards copper iodide? mmol, L-ascorbic acid o, to mmol, N-methylimidazole,
The absorption amount of carbon monoxide was determined in the same manner as in Comparative Example Z, except that the amount of carbon monoxide was added.

As a result, an absorption amount of carbon monoxide of 7 moles of the iodide group i fi O,j of 1 mole was obtained. As shown in Example G, when no oxygen is added, 1 mol of cuprous iodide and 0. ! The amount of carbon monoxide absorbed is 1 mole, and a comparison with this shows that when L-ascorbic acid is added, the carbon monoxide absorption capacity does not decrease due to contact with oxygen.

〔Effect of the invention〕

The thus obtained reaction mixture useful for gas separation can be used advantageously primarily for the separation of carbon monoxide. For example, synthesis gas obtained by steam reforming or partial oxidation of wholesale hydrocarbons such as natural gas, light naphtha, and heavy oil, and mixed gas containing carbon monoxide obtained as a byproduct gas from coal gasification and steel manufacturing. Mainly carbon monoxide can be separated in high yield from carbon monoxide, etc., and used as a raw material for various chemical reactions.

Claims (3)

[Claims] (1) A selective gas separation material obtained by mixing a copper compound and ascorbic acids in a solvent. (2) The gas selective separation material according to claim 1, wherein the solvent is a solvent containing a nitrogen-containing heterocyclic compound. (3) A gas selective separation material capable of separating carbon monoxide from a mixed gas containing carbon monoxide in high yield.