JPS6233521A - Separation of condensable gas - Google Patents

Abstract

PURPOSE:To pass the condensing components in gas to be separated through a porous film and to selectively separate the same by forming a condensed liquid film to the ultrafine pores of the porous film consisting of a material having affinity to the condensing components in the gas. CONSTITUTION:The porous film 1 is stuck to the surface of the porous base material 2 for rendering mechanical strength and the ultrafine pores 3 are formed to the film 1. The pores are preferably formed to about 10-20Angstrom size in order to separate steam from air. The sepn. of the condensable gas is executed by passing the gas to be separated to the left side of the film 1 and evacuating the gas from several Torr to several tens Torr from the side of the material 2 on the right side by a vacuum pump. The condensing components in the gas are condensed in the pores 3 and the liquid film is easily formed by the wettability of said components and the porous film. Since the right side of the liquid film is sucked by the vacuum pump, the liquid film evaporates. The other components have no affinity to the liquid film and cannot, therefore, pass through the liquid film.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for separating condensable gases, and is particularly applicable to the recovery of gasoline paper, separation of water and alcohol, indoor dehumidification, spray dryer air dehumidification, etc. It is something that can be applied.

(Prior Art) Conventionally, there are various gas separation methods using porous membranes, but as in the present invention, a liquid film of condensed components in the separated gas is formed in micropores, and the difference in affinity with the liquid film is eliminated. The technology for selectively separating gas components using the method is unprecedented before this application.

(Problems to be Solved by the Invention) The present invention solves the problem of I! This method aims to provide a method for selectively separating gas components by forming a 8-condensed component film and utilizing the difference in affinity between the liquid film and the components in the gas. The porous membrane needs to be made of a material that has an affinity for the IcS condensed component so that a liquid membrane can be formed with fine pores. For example, a porous membrane with hydrophilic properties is used to permeate and separate a hydrophilic substance, and a porous membrane with a hydrophobic surface is used to permeate and separate a hydrophobic substance, so that each liquid film can be easily inserted into the micropores. In addition, it is necessary to select the upper limit of the pore diameter so that condensation occurs in the ultrafine pores of the porous membrane. The gas to be separated is passed through a porous membrane with extremely fine pores made of a material that has an affinity for condensation and condensation components in the gas to be separated, and a condensed liquid film is formed in the extremely fine pores to separate the condensed components in the gas to be separated. (2) The method according to claim 1, characterized in that the pore diameter of the ultrafine pores of the porous membrane is about 20 Å or less. Method for separating condensable gases.

(3) The method for separating condensable gas according to claim 1, which uses a porous membrane formed on the surface of a porous base material.

(4) A condensable gas separation method O according to claim 3, characterized in that a side of the porous membrane opposite to the gas to be separated is suctioned with a vacuum pump.

In order to separate hydrophilic substances such as water and ethanol, it is advantageous to form a porous membrane with a substance whose surface is hydrophilic, such as alumina or silica. Silicone resin for separation of hydrophobic substances,
Organic resins such as Teflon and polypropylene can be used.

The porous membrane is often used in the form of a thin layer, and in that case, a porous membrane having micropores may be formed on the surface of the porous alumina tube to provide mechanical strength.

FIG. 1 shows a cross-sectional membrane diagram of a porous membrane. A porous membrane 1 is attached to the surface of a porous base material 2 for imparting mechanical strength, and extremely fine pores 3 are formed in the porous membrane 1. Here, the pore diameter of the ultra-fine pores of the porous membrane is as follows: 81Vin formula % σ: Surface tension of liquid (dyn //III) M: Molecular weight (I/ff+01) P: Density of liquid C9/( ) R: Gas constant (a314x10' erg/aeg@m
ol)! = Temperature (deg) N: Relative pressure P with respect to saturated vapor pressure at a certain temperature.

vapor pressure percentage In addition, the distribution of micropore diameter was measured as the amount of water adsorbed.

A certain amount of the sample having micropores was taken out and placed in a constant temperature device. The temperature is constant at 32°0, and the relative humidity is 15-90e.
s″! and measured the weight increase during that time.
The figure is a graph of the relationship between relative humidity and dimensionless water vapor adsorption amount, and 2oX and tp4X are Kelvin
Obtained from the formula. As is clear from this figure, water vapor is adsorbed even when the relative humidity is small, and the adsorption of water vapor is particularly caused by extremely fine pores. was almost impossible to separate. In addition, if the lower limit of the ultra-fine pore is smaller than the molecular size of the permeable separation component, it will not be able to pass through, so it will inevitably be a certain number.
It is preferable to use a porous membrane having extremely fine pores of about 20 μm.

(Function) Next, the condensable gas separation method according to the present invention will be explained based on a cross-sectional model M of a porous membrane shown in FIG.

The gas to be separated flows through the left side of the porous membrane 1, and is pumped from the right side of the porous base material 2 using a vacuum pump for several torr to several j Qt.
orr, the condensed components in the gas form ultra-fine pores 3
The liquid film is easily formed due to the wettability of the core component and the porous film. The right side of the liquid film evaporates as it is sucked in by the vacuum pump, and the condensation from the left side and the evaporation from the right side are balanced, making it appear as if the condensed components are passing through the porous membrane. In addition, other components in the gas to be separated have no affinity with the liquid membrane and cannot pass through the liquid membrane.

(Example) Two embodiments according to the present invention will be described.

(11 aluminum isopropylate 12.51 to 10
Alumina sol was prepared by adding 17 m/m of concentrated hydrochloric acid and having an outer diameter of 101111%, an inner diameter of 8 m, a length of 201 m, and an average pore diameter of 1.5 μm.

A porous aluminum tube with a pore volume fJCL2CC/l is
After being immersed in the alumina sol for 0 seconds, it was air-dried, and further soaked for 4 seconds.
Heated at 50°C for 30 minutes. ``This operation was repeated 5 times to obtain an ultrafine porous membrane of aluminum and oxide with an average thickness of 10 μm.9.

The pore diameter of this membrane has a relationship with the relative humidity and the dimensionless water vapor adsorption amount as shown in FIG.

The separation membrane module thus produced was subjected to a separation performance test using the separation test apparatus shown in FIG. In the figure, a separation membrane module 5 is housed in a thermostatic chamber 8, receives gas from a condensable gas generator 4, and has a vacuum cock 10. Vacuum pump 7 via cold trap (liquid nitrogen) 6! Aspirate from /c. The inside of the constant temperature room 8 can be kept at a uniform temperature by a blower fan 11 and can be heated by a heater 12 if necessary. Temperature controller 9 Controls the condensable gas generator 0 This test was about water vapor permeation, and the results are shown in Figure 3. The horizontal axis is the relative vapor pressure at each temperature,
The vertical axis is the amount of water vapor permeation. In the figure, ■ is the amount of water vapor permeation calculated assuming that there is no condensation, and ■ is 32°0.
, ■ indicates the transmission test data at 58°0, and ■ indicates the transmission test data at 77°OVc.0 As is clear from this figure, I/
The 1M amount of water vapor permeation, which is a C condensable component, showed a large value, confirming the separation effect.

Furthermore, this figure also teaches that as a property of membranes, the higher the temperature, the higher the permeation rate.

In addition, in this test device, a test was conducted using hydrophobic n-hex/ instead of water vapor as a condensable gas, but almost no permeation was observed.

(2) A commercially available silicone resin was applied to the surface of the porous alumina tube used in Example 11 with a brush, and then the solvent was blown off to form a silicone resin ultrafine porous film with an average size of 10 μm. The pore diameter has a relationship with the relative humidity and the dimensionless water vapor adsorption amount as shown in Figure 4.0 When a separation test similar to Example (1) was conducted using n-hexane as a condensable gas, a large amount of permeation was found. Although the value was 9, no permeation of water vapor was observed.

[Brief explanation of the drawing]

The tX1 diagram is a cross-sectional model diagram of a porous membrane for carrying out the method of the present invention, and Figure 2 is a diagram of a sample having extremely fine pores.
Graph of the relationship between relative humidity and dimensionless water vapor adsorption amount, 3rd
Figures 4 and 4 are graphs showing the relationship between relative humidity and dimensionless water vapor adsorption amount for the porous membranes used in Examples (1) and (2) of the present invention, and Figure 3 is an example of the present invention. (1) K
FIG. 6 is a conceptual diagram of a separation test device for testing the performance of separation membrane modules. Sub-agents 1) Meikoku agent Ryo Hagiwara - Sub-agent Atsushi Anzai Related humidity (6A) Related temperature (%) Figure 3 ゛ Eye hole pressure (%)

Claims (4)

[Claims] (1) The gas to be separated is passed through a porous membrane with extremely fine pores made of a material that has an affinity for the condensed components in the gas to be separated, and a condensate film is formed in the extremely fine pores to condense the gas to be separated. A condensable gas separation method characterized by selectively separating components. (2) The method for separating condensable gases according to claim 1, characterized in that the diameter of the ultrafine pores of the porous membrane is about 20 Å or less. (3) A method for separating a condensable gas according to claim 1, characterized in that a porous membrane formed on the surface of a porous base material is used. (4) A method for separating a condensable gas according to claim 3, wherein the porous membrane is sucked from the side opposite to the gas to be separated using a vacuum pump.