JPS5855005A - Separating membrane for gas - Google Patents

Abstract

PURPOSE:To obtain a separating membrane for gas which has a high rate of permeation and high sepn. performance by coating polysilane which has the repetitive units of the specific formula and is soluble in org. solvents on a porous membrane. CONSTITUTION:The polysilane which has the repetitive units shown in the formula and has 200-100,000 number average mol.wts. is dissolved in an org. solvent such as benzene or toluene, whereby a 1-50wt% soln. is prepd. and the soln. is coated on a porous membrane. The porous membrane of >=1X10<-4> cm<2>/cm<2>.sec.cmHg rate of permeation of gaseous nitrogen is used, for which materials are not particularly limited, and may be any of hollow yarn-, tube- and flat plate-like shapes. Further a coating layer can be laminated on the surface of the polysilane membrane by plasma polymn., etc. The rate of permeation, (CC/cm<2>.sec.cmHg, X10<-6>) in one embodiment is N2(0.495), O2(1.37), CO2(6.63), He(2.36), H2(3.49).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an expanded gas separation membrane. Gas separation membranes are required to have a high i separation rate and a large i permeation rate for gas. In order to satisfy such performance, it is conceivable to have a structure in which the membrane layer that provides substantial separation performance is present as thin as possible and is held by a porous layer. Various methods have been devised for manufacturing membranes having such a structure. For example, a method of superimposing a thin film prepared separately on a porous layer, a method of forming an orthotropic film in which a skin layer and a porous layer coexist at once, a method of forming a thin film on a porous layer directly from a cymonomer by various methods, etc. There are methods such as forming a thin film by polymerization or the like, or forming a thin film by coating with a polymer solution and then evaporating the solvent.

These Il! Among the S methods, the method of forming a thin film layer by coating a porous membrane with another polymeric material is a method that can be applied to relatively many types of polymeric materials, but the film thickness If it is made too thin, it will cause defects and the separation performance will be lost, so it is necessary to coat it thicker than a certain level, and if it is coated too thin, the transmission rate will decrease. Therefore, in order to compensate for these drawbacks, it is necessary to select a material that has relatively high gas permeability and good separation performance.

The present inventors have developed a polymer material suitable for such a method.
After extensive research, it was discovered that by coating a porous membrane with polysilane, a membrane with a high permeation rate and high separation performance could be obtained, and the present invention was achieved. That is, the gist of the present invention is to provide a repeating unit of formula -81- (wherein !l and R' represent either an aliphatic hydrocarbon residue R' group or an aromatic hydrocarbon residue). The present invention relates to a gas separation membrane formed by coating a porous membrane with polysilane soluble in an organic solvent.

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

Illustrated.

(1) Polysilane obtained by condensing methylphenyldichlorosilane with metallic sodium ζlium (2) Polysilane obtained by condensing diphenyldichlorosilane 7' with metallic sodium (3) Methylphenyldichlorosilane and dimethyldichlorosilane Polysilane obtained by co-condensing chlorosilane (4) Polysilane obtained by co-condensing diphenyldichlorosilane and dimethyldichlorosilane with gold (5) Obtaining by co-condensing methylphenyldichlorosilane and diphenyldichlorosilane Polysilane (6) A linear polysilane obtained by condensing dimethyldichlorosilane with a soluble polysilane obtained by reacting polydimethylsilane with sodium naphthalene is not suitable for use as it is insoluble in organic solvents.

The molecular weight of the polysilane used in the present invention is not particularly limited, but a number average molecular weight of Q0 to 10,000 is suitable.

Next, the polysilane thus obtained is used by dissolving it in an organic solvent.
In addition, the solvent is particularly limited as long as it is relatively easy to remove the solvent, has a low boiling point, and does not dissolve the porous membrane that serves as the support.

It depends on the Class 11 material of the porous membrane, but for example, benzene, toluene, etc. can be used.

The porous membrane used in the present invention has a sponge-like structure with pores open on both sides. ) txio″d/ with the amount of permeation in question
d・8＠O＠3Hg or more. Such membranes can be made by various methods or by eluting additives.The type of material for the porous membrane is not particularly limited, but examples include polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, and porous membranes. Chil methacrylate, polyacrylonitrile, polycarbonate, polyphenylene oxide, polyamide, polysulfone, polyether sulfone, polysulfonamide, boribipe. Inorganic materials such as glass can also be used. Dissolve polysilane in an organic solvent,
The solution concentration when coating a porous membrane varies depending on the molecular weight and molecular weight distribution of the organosilicon polymer compound and the type of solvent, but preferably 1 to 10% by weight! 40% by weight. If the concentration is less than 1% by weight, the thickness of the membrane to be coated will be thinner, and the gas permeation rate will be high, but sufficient separation performance will not be obtained; Although membrane separation performance can be obtained with a thicker membrane, the gas permeation rate becomes lower. Generally, the amount of polysilane coated is selected to be Q/111!7 to 10 per area la of the porous membrane. The thickness of the porous film is not particularly limited, but is preferably ioμ to 1000μ, and the method of coating the porous film with dissolved N of the organosilicon polymer compound is not particularly limited, but Porous membranes can be immersed in water, or a solution of a five-layer polymer compound can be cast onto the surface of a porous membrane.

The shape of the porous membrane can be hollow fiber, tinib or flat, and can be used as a substitute for these. Moreover, the membrane of the present invention can be used for gases, especially oxygen,
It can be used to separate from each other gas mixtures containing at least one of the following gases: nitrogen, carbon dioxide, carbon oxide, hydrogen, helium, methane, argon.

For example, separation of nitrogen and oxygen in the production of tθ hydrogenated air, separation of methane and helium in the recovery of helium from natural gas, argon and hydrogen in the recovery of hydrogen from hydrogenation reaction exhaust gas, Separation of methane and hydrogen, nitrogen and hydrogen,
It can be applied to the separation of carbon monoxide and hydrogen in the recovery of hydrogen from cracking gas, and the separation of carbon dioxide and nitrogen in the recovery of carbon dioxide from combustion gas.

Next, the present invention will be explained in detail with reference to Examples, but the content of the present invention is not limited to the Examples.

Reference example: 100It flask was filled with metallic sodium/0. /1
Phenylmethyldichlorosilane J,t g,! with xylene gOM! : Dimethedichlorosilanco 3.3g
The mixed silane containing silane was heated at 0° C. to deactivate the remaining sodium from the reaction and was separated into a solid precipitated portion and a solution portion.

After washing each part thoroughly with water and drying, remove the solid part from 7.4.
Polysilane 1 with a weight of 3.01 was obtained from the solution portion.

Example 1 Polysilane of ° was collected from the solution portion obtained in Reference Example 1 and dissolved in citoluene to make a 30% solution. A commercially available Millipore filter (trade name) was attached to a test device by Michiru Okino, and various gases were collected. The permeation rate was determined.

The surface area of the membrane was measured using MID from a high-purity gas stove and a JA121F gas stove under a controlled pressure of -atmosphere. The temperature of the gas and charge was 13°C to 11°C.

Permeation rate Rt of various gases per unit area (/d), unit pressure difference (/cmllg), unit time (1 second)
Capacity of gas permeating <cc> t! - Expressed in terms of standard conditions. Separation performance was also expressed as the ratio of the permeation rates of various gases.

Transmission rate Mt #, ? j X 10-' CC(8
TP)/cd・sec”ct*FilO,/, 37X1
0-1'”'Oz 6.l?X
/(7-' IfH8ko, JAX10-”
zHv j, +? X10-'z
Separation performance (permeation rate ratio) 1. Ko, l ■shi'M, /3. Da He7'M* 'I, E H□/M, ? , / cQL/10* da, j He, 〆t] goose l・riat 10x
:i-s Comparative Example I The permeation rate and separation performance of various gases for the commercially available Millipore filter (trade name) used in Example 1 were measured in the same manner as in Example 1.

Transmission speed N! ko, lda xto-1(:!0(8TP)Δ-
・Second・exsTIIio! H2/Ml Separation performance (permeation rate ratio) 0.7M, 0.7H2/Ml Example 1 except that porin 2 from the solution portion obtained in Reference Example! was dissolved in toluene to make a JJ weight solution. A membrane was formed in the same manner as above, and the permeation rate and separation performance were measured.
゛Transmission rate It j, &/X 10-' C0(8TP)/c
sf*see*-jlH2J, &7X10-"t
t Separation performance (permeation rate ratio) Go to 4 /IF Patent applicant Mitsubishi Chemical Industries, Ltd.

Claims (1)

[Claims] ■ (1) A repeating unit of the formula -81- (wherein Fj and R' represent either an aliphatic hydrocarbon residue R' or an aromatic hydrocarbon residue) The gas component I! according to claim 1, which is a polysilane which is a gas separation membrane formed by coating a porous membrane with a polysilane which is soluble in an organic solvent and has the following properties: film