JPH01310713A - Gas separation membrane and its preparation - Google Patents

Abstract

PURPOSE:To separate and concentrate oxygen, carbonic acid gas, and steam in air by dipping porous glass in an alkoxysilane solution, drying the glass in air, and then making amino-basic compound adhere to the whole surface of the glass by the method, e.g., a reaction with amino compound. CONSTITUTION:Porous glass in an arbitrary shape is dipped in a solution of an alkoxysilane or titanium (alkoxy-group is reacted with hydroxy on the surface of the glass), and after dried in air, the glass is reacted with an amino-basic compound such as monomethylamine, pyridine derivatives, etc., so as to make amino-basic compound adhere to the whole surface of the porous glass. The membrane thus obtained can adsorb oxygen, carbonic acid gas, and steam easily in the surfaces of fine pores, and because surface diffusion phenomenon is caused, oxygen, carbonic acid gas, and steam in air can be concentrated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas separation membrane that separates and concentrates oxygen, carbon dioxide, and water vapor in the air, and a method for manufacturing the same.

[Conventional technology]

A membrane separation method is known as a method for separating and concentrating oxygen, nitrogen, water vapor, carbon dioxide, etc. in the air, and much research has been conducted in recent years on this method because it is inexpensive and almost maintenance-free.

At present, such concentrated oxygen is used for medical purposes and for energy-saving purposes such as combustion, while nitrogen is expected to be used for explosion-proof disaster prevention purposes, and carbon dioxide and water vapor are expected to be used for environmental control. .

As mentioned above, the technology for separating and concentrating oxygen and nitrogen from air is the cryogenic separation method, in which the air is cooled and separated using a device that utilizes the difference in boiling point between oxygen and nitrogen.

Adsorption methods on the solid surface of zeolite, carbon sorb, etc. that utilize the adsorption power for gases and the difference in adsorption speed to separate the gases are known.

[Problem to be solved by the invention]

In the former method, the equipment is large, so it is installed at a location far from the user, transported to the user via pipe, and then filled into cylinders and transported to the user, which reduces costs. In addition to being extremely expensive, it is inconvenient for users to handle as they are subject to legal regulations under the High Pressure Gas Control Law.

In the latter method, the concentration is not constant with respect to time (
A batch system has to be used, and since water vapor and polar gases deactivate the zeolite, they must be removed before adsorption, making the operation complicated.

On the other hand, the membrane separation method described above is preferable because it not only can solve the above-mentioned problems, but also consumes less energy than the two methods described above.

However, when gas is separated through a membrane, the permeation rate is slow, making it difficult to put it into practical use.

In other words, conventional gas membrane separation technology uses a nonporous membrane as a membrane for separating and concentrating gases such as oxygen and nitrogen, and when feed air is supplied to the membrane surface, the gas in the air is absorbed by the membrane. It dissolves on one side, diffuses to the other side, and falls off. In other words, it passes through the membrane. Since the solubility and diffusion rate vary depending on the special gas, the concentrating effect is utilized, and since it is impossible to increase the permeation rate beyond a certain point, the permeation rate becomes slow.

Therefore, an object of the present invention is to provide a gas separation membrane that can increase the permeation rate and a method for manufacturing the same.

[Means and effects for solving the problem] As a result of intensive research to improve the slow permeation rate of non-porous membranes, the present inventor found that
We have discovered a gas separation membrane that can efficiently condense oxygen, carbon dioxide, and water vapor in the air without using a nonporous membrane, and whose permeation rate is significantly higher than that of a nonporous membrane.

In other words, when gas passes through a porous membrane that has through-holes with an average pore diameter smaller than the gas mean free path, the permeation rate of each gas is proportional to the square root of the molecular weight, and the gas permeation rate at this time is negligible. 10-1000 times faster than porous membranes.

However, since the difference in molecular weight between oxygen and nitrogen is small, it is almost impossible to concentrate oxygen or nitrogen from air.

Furthermore, if the pore surface has an affinity for a specific gas such as oxygen or nitrogen, gas adsorption or dissolution will occur on the pore surface. As a result, the concentration of the gas adsorbed on the pore surface increases, and on the opposite side, a concentration effect of the adsorbed gas occurs.

On the other hand, oxygen and carbon dioxide gas are electrophilic.

The present inventor focused on the above points, and by making the pore surfaces in a porous membrane basic, the pore surfaces will increase their affinity for oxygen and carbon dioxide gas in the air, and at the same time increase their hydrophilicity. As a result, oxygen, carbon dioxide, and water vapor are adsorbed on the inner surface of the pores,
Surface diffusion phenomena of oxygen, carbon dioxide, and water vapor occur on the pore surface, so the oxygen, carbon dioxide, and water vapor in the air become concentrated as they pass through the pores, and this result becomes more pronounced as the base strength increases. I found it.

Specifically, it is a gas separation membrane that has an amino base compound on the surface of porous glass and on the surface of the pores.This membrane can not only concentrate oxygen, carbon dioxide, and water vapor in the air, but also has a high permeation rate, making it suitable for practical use. It can be provided to

Examples of the amino base compounds include mono- and dimethylamine, monomethylamine, pyridine derivatives, and quinoline derivatives.

The shape of porous glass may be hollow, hollow tubular, flat, spiral, etc.

In addition, as a result of intensive research into methods for manufacturing such gas separation membranes, we found that after coupling the porous glass surface with a silane coupling material or titanium coupling material, we reacted it with an amino-based substance to basify it. They found that it was possible to produce gas separation membranes by doing this.

According to this production method, since it is highly reactive, the reaction can be carried out at room temperature, and the reaction can be precisely controlled, so that the strength of basification can be arbitrarily controlled.

The aforementioned titanium and silane coupling materials include methoxy, ethoxy, and isopropoxy, each of which has an alkoxide group, and these alkoxide groups usually react with hydrogen groups on the glass surface.

In addition, groups that react with bases such as amino groups are 5iCC,
5iC=CSSiHSSiCf! , are preferably used in combination.

Specifically, this is a manufacturing method in which a porous glass is immersed in an alkoxide solution, pulled up, left to dry in the air, and reacted with an amino-based substance to adhere an amino-based base to the entire surface of the porous glass.

As the alcoquinrad, (R4O)nS I R
2, however, R4 is CH3, C2H5, C3H7, n is 1
~3, R2 is H2C=CH.

C3H8N-C2H4NH2, C3H8NH2, R2 HC-C-C-0-C3Hs, \1 CH1 CHI -C-0-T i -(OC+ Ht -NH
-C+ Ht -NH+
2R5) One of 2 is preferred.

〔Example〕

The present invention will be explained in detail below.

Example 1 An alkoxide solution containing 2 mol % of aminopropyltrimethoxine in absolute ethanol is prepared.

Next, a porous hollow tube made of borosilicate glass (bore diameter 250
After immersing the sample in the alkoxide solution, the pore surface is silylated and the solvent is removed by evaporation.

When the porous glass hollow tube membrane thus produced was subjected to an air permeation test, the oxygen concentration was 23% (pressure difference 76 Hg+nn+) and the permeation rate was 8 cc/c paddle/min.

As a comparative example, a polydimethylsiloxane membrane was prepared in a similar porous glass hollow tube and a similar air passage test was conducted, and the permeation rate was 0.2 cc/c/min.

Example 2 The same porous glass hollow tube as in Example 1 was immersed in a 2 mol% solution of r-glydoxypropyltrimethoxysilane and anhydrous ethanol, dried, and then immersed in a 2% solution of quinoline and sulfonic acid, and then heated at room temperature. After being left for 10 hours, it was left in the air for another 24 hours, then immersed in a methanol solution to remove excess quinoline, and left to dry in the air.

When the porous glass hollow tube membrane thus produced was subjected to an air passage test in the same manner as in Example 1, the oxygen concentration was 28% (pressure difference 76 Hgmm), and the permeation rate was 5 cc/e.
It was ♂/min.

〔Effect of the invention〕

Since the amino base compound is attached to the surface of the porous glass and the pore surface, it has an affinity for oxygen, carbon gas, and water vapor in the air, and can condense oxygen, carbon dioxide, and water vapor in the air.

In addition, since it is porous, the permeation rate can be increased to make it suitable for practical use.

Applicant Komatsu Manufacturing Co., Ltd. Representative Patent Attorney Masaaki Yonehara

Claims (2)

[Claims] (1) A gas separation membrane characterized by having an amino base compound on the entire surface of porous glass. (2) A method for producing a gas separation membrane, in which porous glass is immersed in an alkoxide solution, left to dry in the air, and reacted with an amino-based substance.