JPS61174920A - Permselective membrane of gas - Google Patents

Abstract

PURPOSE:To obtain a permselective membrane of gas high in the permeability constant of oxygen and in the coefficient of separation of oxygen and nitrogen by adding a compd. having amino group to a polymer wherein fluoroalkyl ester of acrylic acid or methacrylic acid is polymerized. CONSTITUTION:A permselective membrane of gas is constituted of a polymer wherein a compd. of 1->=2 kinds of fluoroalkyl esters of acrylic acid or methacrylic acid is polymerized and >=100 deg. of polymerization is preferable. It is necessary that a compd. having amino group such as a primary - tertiary amine compd. and ethanolamine compd. is blended in addition to the polymer in the period forming the membrane and the weight to be added in preferably 5-50wt% based on the polymer. The permeability constant of oxygen for this membrane is (1-10)X10<-9>cm<3>cm/cm<2>seccmHg and the coefficient of separation of oxygen and nitrogen is 2-4.

Description

[Detailed description of the invention] The present invention relates to a selectively permeable membrane.

More specifically, the present invention relates to a selective gas permeable membrane that is easy to manufacture, has mechanical strength as a thin membrane, and has a large permeability coefficient. The present invention relates to a selective gas permeable membrane suitably used to obtain air enriched with highly concentrated oxygen.

Although there are conventional methods for separating mixtures using membranes, these methods use reverse osmosis membranes or ultra-permeability membranes and are mainly used for liquids. On the other hand, separation of mixed gases using membranes has rarely been seen again because its selectivity and permeation rate were insufficient.
On the contrary, applications of the gas permeation phenomenon in films have been centered on gas barrier films for packaging.

However, in recent years, many proposals have been made for gas separation and concentration using membranes containing polymers as a main component and utilizing differences in gas permeability depending on gas temperature.

On the other hand, air is a mixed gas that is highly desired to be separated in industry. It goes without saying that oxygen, which accounts for approximately 20% of the components of air, is an indispensable gas for humans to survive, but it is also used in industrial applications such as internal combustion engines, the steel industry, the food industry, It is a very important gas used in medical equipment, waste treatment, etc. Therefore, there has been a strong desire for a method to efficiently, inexpensively, and easily separate oxygen from air.

In membrane separation methods, it is difficult to obtain air with a high purity oxygen concentration through one stage of membrane separation, but several attempts have been made to obtain air enriched with oxygen to a certain degree. This is a method using a membrane whose main component is a typical Namonohorganopolysiloxane. However, although a membrane containing organopolysiloxane as a main component has a large oxygen permeability coefficient, the separation coefficient between oxygen and nitrogen is small at about 2, and there is a limit to the oxygen concentration of the oxygen-enriched air that can be obtained. Several other methods (ζ) have also been proposed, but in all of them the oxygen permeability coefficient is less than 1/lo compared to a membrane mainly composed of organopolysiloxane, making it difficult to put it into practical use. previously proposed a membrane made of a polymer of fluoroalkyl acrylate and/or fluoroalkyl methacrylate.However, this was still insufficient.Therefore, a membrane with higher permeability and separation coefficients was desired.

Therefore, the present inventors investigated various improvements to membranes made of polymers of fluoroalkyl acrylates and/or fluoroalkyl methacrylates, and as a result, they arrived at the present invention. That is, by using a membrane made of a blend of a polymer of fluoroalkyl acrylate and/or fluoroalkyl methacrylate and a compound having an amino group, enriched air with a high oxygen concentration can be efficiently obtained. I found it. The purpose of the present invention is to
An object of the present invention is to provide a selective gas permeable membrane having a high oxygen permeability coefficient and a high oxygen-nitrogen separation coefficient when air is passed through the permeable membrane to obtain oxygen-enriched air.

The reason why the membrane made of the above blend is excellent as an oxygen-enriching membrane is not clear, but the interaction between fluorine atoms and amino groups in the membrane made of the above blend has a positive effect on oxygen permeability. It is thought that there are.

The present invention will be explained in detail below.

The polymer constituting the selective gas permeable membrane of the present invention can be obtained by polymerizing fluoroalkyl acrylate and/or fluoroalkyl methacrylate. Desirably, it is obtained by polymerizing one or more compounds selected from compounds represented by the general formula % (C1-16 alkyl group containing 8 or more fluorine atoms).

More specifically, these compounds include trifluoromethyl ester, trifluoroethyl ester, perfluoroethyl ester, perfluoropropyl ester, perfluorobutyl ester, perfluoropentyl ester, perfluorohexyl ester of acrylic acid and methacrylic acid. ester, perfluoroheptyl ester, perfluorooctyl ester, perfluorononyl ester, perfluorodecyl ester, perfluorolauryl ester, perfluoropalmityl ester,
These include perfluorostearyl ester, perfluorohydroxyalkyl ester, perfluoroacetylalkyl ester, and the like.

There are no particular restrictions on the polymerization method for the above compound, and generally well-known polymerization methods can be used. Examples include radical polymerization using an initiator, ionic polymerization, polymerization using a Ziegler catalyst, or polymerization initiated by radiation irradiation, ultraviolet irradiation, etc., but radical polymerization is usually carried out because it is simple. Also, nokuru polymerization,
Any method such as solution polymerization using a solvent, suspension polymerization, or emulsion polymerization may be used. There are no particular restrictions on the polymerization temperature, and there are no particular restrictions on the polymerization pressure.

There is no particular restriction on the degree of polymerization of the obtained polymer, but it may be at least the degree of polymerization at which film-forming properties are exhibited. Desirably, the degree of polymerization is 100 or more.

:R or a C1-16 alkyl group)
class, secondary and 8th class amine compounds, or C2H4
Examples include ethanolamine compounds represented by (OH group).

Specific examples of amine compounds include diethylamine, triethylamine, propylamine, dipropylamine,
tripropylamine, butylamine, dibutylamine,
tributylamine, hexylamine, diethylamine,
These include trihexylamine, octylamine, dioctylamine, and trioctylamine. Specific examples of ethanolamine compounds include monoethanolamine, jetanolamine, and triethanolamine.

There is no particular restriction on the method of blending the polymer and amine compound constituting the selective gas permeable membrane of the present invention, and a conventional method may be used. In particular, a solvent blend method using a solvent is particularly preferably used.

Regarding the amine compound added to the above polymer, if the amount of the amine compound added is too small, the blending effect will not be exhibited, and if the amount of the amine compound added is too large, the mechanical strength of the membrane will be low. Since the selective permeability of oxygen also decreases, the amount of the amine compound added is usually 5% by weight to 50% by weight based on the above polymer. Preferably 10
The amount% to 40! j1%.

Generally well-known methods are also applicable for the preparation of membranes. For example, it can be obtained by dissolving a polymer in a good solvent such as acetone, methyl ethyl ketone, or ethyl acetate, casting it onto a smooth glass or metal plate using a doctor knife, evaporating the solvent, and then peeling it off. The thickness of the membrane is adjusted by the concentration of the polymer solution and the thickness of the cast solution. It can also be obtained by casting a polymer solution onto a porous support using a doctor knife and evaporating the solvent.

Furthermore, although specific forms of membranes are generally known, such as flat membrane, tubular, hollow fiber, and filamentous forms, the present invention can be applied to any form.

As mentioned above, the selective gas permeation membrane of the present invention has a large permeation coefficient, and when obtaining oxygen-enriched air from air using the membrane of the present invention, it is difficult to obtain oxygen-enriched air from air using the conventional selective gas permeation membrane. Compared to membranes, it has a higher separation coefficient between oxygen and nitrogen and a higher oxygen permeability coefficient, showing superior performance.

The selective gas permeable membrane of the present invention can separate helium from natural gas, decompose and recover produced gas and raw material gas from synthesis gas, remove radioactive noble gas from reactor exhaust gas, and recover hydrogen gas from petroleum waste gas after desulfurization. It is used to remove air pollutants such as sulfur dioxide gas and hydrogen sulfide gas. In particular, as mentioned above, it is suitably used for concentrating oxygen in the air, supplying oxygen-enriched air to combustion systems, supplying oxygen-enriched air to medical equipment, and purifying rivers. It can be used for supply, etc.

The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited to these examples in any way.

In addition, the permeability coefficient is d-cIg1/cfI-8eC-cM
It is expressed in units of Hg, and the separation coefficient is, for example, in the case of oxygen and nitrogen, separation coefficient α (PO / PN2) = oxygen permeability coefficient / nitrogen permeability coefficient.

Example 1 800. Add 100 g of water, 0.1 g of polyvinyl alcohol, and 4 y of common salt to the four-bottle flask described in d, and stir to dissolve while blowing nitrogen. There 2.2.2-
Trifluoroethyl methacrylate 20f and α, α′-
Add 0.08f of azobis-isobutyronitrile. Then, polymerization was carried out at 60"C for 7 hours. After the polymerization, the polymerized product was washed with water and vacuum dried at 50"C for 24 hours.The yield of the obtained polymer was 14f. The resulting polymer 51 was dissolved in 45 μm of acetone, and the solution was cast on a glass plate to a thickness of 250 μm and air-dried.The membrane was then peeled off from the glass plate and an air permeation test was performed. Transmission coefficient is 1.27 x 10
ad ・cm/al-sea ・cmHg, and a
(Pog/PN2)=3.8.

Example 2 Polymer 51 obtained in Example 1 is dissolved in acetone 459, and tri-n-octylamine 1y is further added and dissolved. The solution was cast onto a glass plate to a thickness of 250μ and air-dried. The membrane was then peeled off the glass plate and tested for air permeation. The permeability coefficient of oxygen is 2
．． l OX 10 cd ・cm/ad -sec
−cmHg, and α(POg/PNz) =
It was 4.2.

Example 8 Polymerization was carried out under the same conditions as in Example 1, except that 2.2°8.3-tetrafluoropropyl methacrylate 20f was used instead of 2.2.2-trifluoroethyl methacrylate 20y. The yield of the obtained polymer is 11. Of
Met. A film was formed in the same manner as in Example 1, and a permeation test was conducted. The permeability coefficient of oxygen is 2.56X10”cd = an/c
j ・SeC・cmHg, and a (Po27PNz
)=8.4.

Example 4 Polymer 5F obtained in Example 8 is dissolved in 45f of acetone, and 1.25F of tri-n-butylamine is further added and dissolved. The solution was cast onto a glass plate to a thickness of 250μ and air-dried. The membrane was then peeled off the glass plate and tested for air permeation. The oxygen permeability coefficient is 1.06 x 10 d 'cm10d ・SeC・
cm Hg, at Po27PNz) = 2.2
It was 2 teas.

Claims (3)

[Claims] (1) A selective gas permeable membrane comprising a blend of a polymer of fluoroalkyl acrylate and/or fluoroalkyl methacrylate and a compound having an amino group. (2) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R:
A polymer obtained by polymerizing one or more compounds selected from compounds represented by H or CH_3, R_1: an alkyl group having 1 to 16 carbon atoms containing 3 or more fluorine atoms, and an amino group. The selective gas permeable membrane according to claim 1, characterized in that it is made of a blend with a compound having the following. (3) A compound with an amino group has a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R_2, R_3, R_4: H or alkyl groups of C_1 to _1_6) or a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (R_5, R_6, R_
7:H or C_2H_5OH group) The selective gas permeable membrane according to claim 1.