JPH01297122A - Gas separation device with hydrophobic porous film - Google Patents

Abstract

PURPOSE:To prevent solvent dissipation, reduce the thickness of a liquid film and make possible applications at high pressure differences by employing a material consisting of a thin film of liquid containing a carrier held in a laminated form with a film composed of only hydrophobic pores of 0.1mum or less as a liquid film for gas separation. CONSTITUTION:A material consisting of a thin film of liquid containing a carrier held in a laminated form with a film 1 composed of only hydrophobic pores of 0.1mum or less, is used as a liquid film for gas separation. This liquid film is supported by a hydrophobic film which allows gas to permeate freely but does not allow a solvent to penetrate. The solvent does not leak if pressure is applied to the liquid film. Consequently, it is possible to operate the gas separation device with a liquid film of reduced thickness and large pressure differences for improved performance. Furthermore, the solvent in the liquid film does not dissipate.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas separation device for separating and concentrating a target gas from a gas mixture.

(Prior Art) Conventionally, there is a method of using an iα body membrane as a gas separation method. A porous support membrane is impregnated with a liquid in which the separated gas has a high solubility (often containing a carrier in addition to the solvent), and one side is pressurized more than the other to dissolve the target gas and release it to the other side. . Nonvolatile metal salts, metal complexes, and the like are often used as carriers.

An example is an olefin gas selective permeation membrane that uses silver ions as a carrier. This is a porous hollow fiber made of polyolefin using silver ions as a carrier and impregnated with an aqueous solution of silver nitrate. The equilibrium constants of silver ions and olefins are well known: ethylene = 98, propylene = 9.
7. Cyclohexene = 860. , a liquid membrane containing silver ions selectively permeates olefins, and is 99-99°9 from a mixed gas containing equimolar amounts of ethane, methane, and ethylene.
% of ethylene is exchanged, and the separation coefficient of ethylene is 210~
It is 290. The hollow fiber used had an outer diameter of 2.24 mm.
The inner diameter is 0.84 mm.

Research on the practical use of this example was carried out using a medium-scale device, but since the solution in the liquid membrane was water, it was not possible to prevent the water contained in the membrane support from dissipating, and the method was abandoned. There is also a hydrogen sulfide selective permeation membrane that uses carbonate ions as a carrier. There are also selectively permeable membranes that use hemoglobin or myoglobin as carriers to separate and concentrate oxygen from the air.

Furthermore, there is a method in which platinum wire mesh is used as electrodes on both sides of a liquid membrane, and an electrically propelled membrane transport phenomenon is utilized. In this method, a liquid film of ferrous chloride and ferric chloride dissolved in a formamide solution is sandwiched between platinum electrodes.

The aim is to electrically transport and separate the

Transport separation can also be performed for C○ using the same principle.

(Problems to be solved by the invention) In conventional liquid membranes containing carriers, the solvent of the liquid membrane is mainly water, so it is impossible to prevent the moisture contained in the membrane support from dissipating. Therefore, a porous support is required. However, since the membrane support is porous, it is difficult for the dissolved liquid to diffuse, and the membrane support cannot exhibit sufficient ability as a carrier. If the porous membrane support is made thinner in order to improve its performance, the strength of the membrane will decrease, making it difficult to reduce the membrane thickness to 0.5 mm or less. In order to perform gas separation efficiently, it is necessary to create a large pressure difference, but there are drawbacks such as the inability to create a large pressure difference because the strength of the membrane and separation capacity are inversely proportional.

Furthermore, separation methods that utilize electrically propelled membrane transport phenomena use formamide, which has a high vapor pressure, and aqueous solutions with high vapor pressure are not suitable for use because water evaporates and the liquid film is destroyed. . Further, there were drawbacks such as the need to bond an unnecessary silicone membrane of 30 mm with respect to gas separation in order to prevent the liquid membrane from being destroyed by differential pressure.

(Object of the Invention) The gas separation device of the present invention eliminates the above-mentioned drawbacks of the conventional example. In order to prevent the dissipation of the solvent in the liquid film, stabilize the liquid film, and improve its performance, the liquid film is thinned and a large pressure difference is applied to enable operation. As a result, it is an object of the present invention to provide an apparatus capable of stably and efficiently separating gases over a long period of time.

(Means for Solving the Problems) In the present invention, a thin film of a liquid containing a carrier is held in a layered manner by a film consisting only of hydrophobic pores of 0°1 micron or less.

Therefore, since the liquid film is held by the hydrophobic film, the solvent will not leak even if pressure is applied to the liquid film. 0. 1
The water pressure resistance of a membrane consisting only of hydrophobic pores of micron size or less is 5 voltage or more in the case of water. Furthermore, since these pores are hydrophobic, aqueous solutions cannot enter them, but gas can freely enter and exit, so that the effect on the diffusion of separated gas is small. There is also the advantage that the smaller the diameter, the more Knudsen flow occurs and the influence between individual molecules is reduced.

(Function) Since the gas separation device of the present invention is configured as described above,
All the shortcomings of traditional methods have been eliminated. That is, even if the solvent evaporates, the liquid film containing the carrier can be supplied from the outside, so there is no destruction of the liquid film. Since the strength of the entire membrane can be provided by the hydrophobic membrane, the liquid membrane containing the carrier can be made thinner in order to improve the separation ability. In other words, since the membrane can be made thinner, the carriers can be easily moved, and the moving distance can be shortened, so that the separation capacity can be increased. In order to efficiently separate gases, it is necessary to create a large pressure difference, but because the strength of the membrane is supported by the hydrophobic membrane, it has become possible to create a large pressure difference. The gas permeation rate of this membrane is sufficiently faster than that of a liquid membrane and has the advantage that the presence or absence of this membrane does not affect the permeation of the separated gas.

Furthermore, for those that utilize electrically propelled membrane transport phenomena, a membrane consisting only of hydrophobic pores of 1 micron or less can be used as an electrode, or by bonding a conductive material to the membrane. Can be used.

Since the gas separation device of this invention is configured as described above,
Compared to devices using conventional liquid membranes, gas separation can now be performed more efficiently, stably, and easily.

(Examples) Examples of the present invention will be described below, but these examples do not limit the present invention.

The basics of the present invention are a structure in which a hydrophobic membrane and a liquid membrane containing a carrier are sandwiched together as shown in Fig. 1.Even if the solvent for the liquid membrane decreases, it can be supplied from the outside with a pump, and the solvent reservoir can be used. It may be provided. A mesh or the like may be inserted into the liquid film to prevent the hydrophobic films from coming into contact with each other.

FIG. 2 shows a hydrophilic porous layer bonded onto a hydrophobic membrane. It is used to form a liquid film by allowing liquid to seep into a hydrophilic porous layer, and can easily reach a film thickness of 100 microns or less. FIG. 3 shows a structure in which a hydrophobic portion is partially provided on the porous layer of FIG. 2. When the gas to be separated and the liquid for liquid membrane are flowed simultaneously, the gas adheres to the hydrophobic portion and is easily separated by the liquid membrane. By doing this, the liquid for the liquid film can also be easily supplied. FIGS. 4 and 5 show the membrane shown in FIG. 3 in the form of a vibrator, and gas separation is carried out by simultaneously flowing a mixed gas and a liquid containing a carrier inside or outside the pipe. The liquid containing the carrier for the liquid film is in a multiphase flow with the gas,
Alternatively, it may be supplied intermittently in the form of a mist.

As the membrane medium, in addition to aqueous solutions, organic solvents such as ethylene glycol can also be appropriately used as long as they do not wet the hydrophobic membrane. It can be used by introducing a carrier of ionic species as a counterion into an ion exchange resin and filling the voids with an aqueous solution.

The more pores the hydrophobic membrane has than 0.1 micron, the better. Hydrophobic fine particles such as acetylene black and PT
It is also possible to mix fine particles of water-repellent resin such as FE and then bind them together using a hot press or the like to form a film.

A water-repellent porous film made of roughly stretched PTFE, polyethylene, polypropylene, etc. may also be used.

Since the separation ability is proportional to the number of pores in contact with the liquid membrane, it is desirable to provide unevenness at the interface between the water-repellent membrane and the liquid membrane.

The porous layer for retaining a liquid containing a carrier may be a hydrophilic polymer membrane, or a membrane made of silica or alumina fine particles bonded together with a polymer. Furthermore, in order to create irregularities at the interface between the water-repellent film and the liquid film, a film containing a mixture of water-repellent portions and hydrophilic portions can be bonded to the water-repellent film.

Examples of targets as separated gases are 02) C02) H2S, S
O2) Co, No, olefin, etc., and the carriers are hemoglobin, bicarbonate, carbonate, ethylene glycol, Cu~ ion, Fe~ ion, Ag+ ion, respectively. FIG. 6 shows the principle of facilitated transport of ethylene using Ag0 ions as carriers. Since the liquid membrane containing Ag' ions is held by a hydrophobic membrane, it can exist stably under pressure, and since there are many pores in the hydrophobic membranes on both sides of the liquid membrane, permeated gas and separated gas are Can be easily moved.

If it is necessary to create a large pressure difference for efficient gas separation, the diameter of the hydrophobic membrane may be made smaller. For example, if the pores are only 0.05 microns or less, then 1
0 kg/am2 or more. At this time, a reinforcing material such as a stainless steel filter may be attached to protect the membrane.

Furthermore, gas separation using electrically propelled membrane transport phenomenon is configured as shown in FIG. As long as the membrane is conductive, the electrode can be used as it is or by supporting platinum or the like as an electrode catalyst. In the case of a non-conductive film, a platinum mesh, a mixture of carbon black and polytetrafluoroethylene, etc. are used by bonding it to the film. This electrode may be a so-called gas diffusion electrode. It is desirable that the reaction layer of this gas diffusion electrode has a fine mixture of hydrophobic parts and hydrophilic parts.

Large Mouse Plate 1 A membrane having only pores of 0.1 micron or less was prepared as follows. Acetylene black with an average particle size of 0.04 μm UL and polytetrafluoroethylene with an average particle size of 0.3 μm are mixed in a liquid phase at a ratio of 7:3, filtered, dried, powdered, filled into a mold, and pressed under pressure. 600Kg/cm2)
Hot press at a temperature of 380℃ for 3 seconds and rapidly cool to a thickness of 0.
．． A membrane 1 was obtained having hydrophobic pores of 3 mm and an average diameter of 0.04 microns.

The distance between two membranes 10 having an electrode area of 6πcm2 prepared as shown in the configuration diagram shown in FIG. 8 is 0.3 mm, and the liquid membrane 5
is further sandwiched between a jig 7 having a stainless steel filter of 4πcn'+2 from both sides, and a high pressure chamber 1° and a low pressure chamber 11 are formed.
has been established. An aqueous solution 5 containing 2 mol of AgNO3 as a carrier was used as a liquid film, and a pulse pump was used to pump the liquid at 0.1 ml/mi.
It was circulated at a speed of n.

At a temperature of 25 degrees, an equimolar mixture of ethylene and ethane is injected into the high pressure chamber at a pressure of 2 kg/cm'', while the low pressure chamber is 10 m deep.
The pressure was reduced to mHg. As a result, ethylene with a purity of 99% or more was obtained. At this time, water is taken away from the liquid film together with the outflowing gas, but this can be avoided by supplying water to the circulating aqueous solution or by controlling the humidity of the separated gas.

A device utilizing the electrically propelled membrane transport phenomenon was constructed as shown in Figure 7. The liquid membrane 5 is made of 0.2 mol of ferrous chloride and 0.2 mol of ferric chloride aqueous solution, and two gas diffusion electrodes 1 with an electrode area of 4πClT12 (0.51 mol of platinum are used)
NO was electrically transported from the cathode chamber 8 to the anode chamber 9 with a gap of 0.5 mm between the electrodes.

Both cathode chamber 8 and anode chamber 9 are filled with the same pressure No.2m.
, A, / cm", from cathode chamber 8 to anode chamber 9
Moved to. The amount of movement and efficiency were superior to the conventional example (effects of the invention) The present invention improves the structure of the liquid membrane for gas separation by forming a thin film of liquid containing a carrier only through hydrophobic pores of 0.1 micron or less. It was held in a layered manner with a film.

Therefore, the liquid membrane is held by a hydrophobic membrane through which gas can freely permeate but not the solvent, so even if pressure is applied to the liquid membrane, the solvent will not leak out.

There is no dissipation of the solvent in the liquid film, and in order to improve performance, the liquid film can be made thinner and the pressure differential can be increased.

As a result, various gases can be separated stably and efficiently.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of the present invention. FIG. 2 shows a membrane in which a hydrophobic pore layer is bonded to a conventional liquid membrane. FIG. 3 shows a membrane in which a hydrophobic portion is further bonded to the membrane of FIG. 2. FIG. 4 is a diagram showing that the membranes of FIGS. 3 and 5 are shaped into a vibrator and supplied as a gas-liquid multiphase flow. FIG. 6 is a conceptual diagram of an ethylene separation device using an Ag liquid membrane. Fig. 7: No concentration device using electrically propelled membrane transport phenomenon using an Fe'' liquid membrane. Fig. 8: Ethylene separation device using an Ag'' liquid membrane. Figure 1 1, Hydrophobic membrane 2) Liquid membrane 3, Porous hydrophilic membrane (liquid membrane) 4, Mixed gas 5, Liquid containing 6, Separated gas Figure 4 Figure 5 Figure 6 C2H4 A4 "+C2HJ → Ag-C,H,. ↑ ↓ -m--5Ag"+c
YoH, -Ag-C,H," 2H4 Figure 8 9, Stainless steel jig 10, high pressure chamber 11, low pressure chamber Procedure amendment (method) % formula % 2) Name of the invention Having a hydrophobic pore membrane Gas separation device 3, relationship with the case of the person making the amendment Patent applicant July 4, 1999 5, column 6 for a brief explanation of the drawings of the specification subject to the amendment, page 12, item 13 of the specification of the contents of the amendment The rows ``Figure 3, Figure 5,'' are replaced by [Figure 2 showing that the membrane in Figure 2 is made into a pipe shape and supplied as a gas-liquid multiphase flow. Figure 5 has been corrected to Figure 3.

Claims (3)

[Claims] (1) A gas separation device comprising a membrane having only hydrophobic pores of 0.1 micron or less and a liquid membrane containing a carrier. (2) A gas separation device using electrical propulsion, characterized in that a liquid membrane is sandwiched between two electrodes having the membrane as set forth in claim 1. (3) A gas separation device characterized in that the electrode according to claim 2 is a gas diffusion electrode.