JPH1085568A - Gas separation equipment - Google Patents

Abstract

[PROBLEMS] To provide a gas separation device using a separation membrane, which can be used at a high temperature, has a high gas (particularly hydrogen) permeation rate and a high gas (particularly hydrogen) separation performance. SOLUTION: In the gas separation apparatus provided with a separation membrane on a porous support, the porous support has a diameter of 10 ° or more and 40 ° or more.
Layer having pores of less than 0 ° and diameter of 400 ° or more and 10,000
A porous silica membrane having a pore size of 2 to 10 mm is formed as the separation membrane on the smaller pore size side of the porous support, comprising at least two layers including a layer having pores of less than 0 °.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas separation device, and more particularly, to a gas separation device using an inorganic separation membrane made of polysilazane.

[0002]

2. Description of the Related Art A gas separation device using a membrane has advantages such as no phase change, simplification of the device and operation, and continuous operation, and is expected as an energy-saving device. I have. Speaking of gas separation membranes, for example, hydrogen separation membranes, they are currently used for recovering hydrogen-rich gas from off-gas in petroleum refining plants and recovering hydrogen gas from purge gas in ammonia synthesis plants. Hydrogen gas is widely used and its demand is high. However, a film that has been put into practical use is a polymer film, and this drawback has the following two points. It cannot be used at high temperatures (200 ° C or higher). Low hydrogen permeation rate. With regard to (1), there is a problem that the application range of the hydrogen separation membrane is limited depending on the temperature, and (3) the processing rate is limited because the speed is low.

[0003] In order to overcome the above problems, research on inorganic (ceramic) membranes has been started, but in the case of ceramic membranes, for example, in the case of porous silica membranes by the sol-gel method, Å order of only hydrogen is passed. It is very difficult to form small holes (that is, it is only possible to control the hole diameter on the order of several tens of degrees, and it is possible to obtain only Knudsen diffusion), and it has been impossible to form a film without pinholes and cracks. Moreover, it has a very long time to manufacture. In addition, SiO ₂ —B ₂ O ₃
For producing a porous ceramics film by forming a complex oxide film such as the above and etching the same (JP-A-7-17780)
However, this method can only control the pore size on the order of several tens of degrees. As a result, the above problem can be solved, but the hydrogen selectivity is low and the performance is insufficient.

[0004] Recently, however, it has been announced that a porous silica membrane having all of the above and hydrogen selectivity has been formed [Asaeda: Catalyst, vol. 36 No. 4, p. 23
8-245 (1994)]. This film is formed by a sol-gel method, and it is said that holes of the order Å are formed. Although the structure is not clarified, it is assumed that the pores are formed by gaps between the gel particles.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned prior art, and has high heat resistance, a high gas permeation rate, a high gas selectivity, and is easy to manufacture. It is an object of the present invention to provide a gas separation device having a porous silica membrane having a pore diameter of several to 10 degrees.

[0006]

According to the present invention, first, in a gas separation apparatus utilizing a separation membrane provided on a porous support, the porous support has a diameter of 10 ° or more and 400 ° or more.
Layer having pores of less than と and diameter of 400 径 or more and 100,000
少 な く と も comprising at least two layers with a layer having pores of less than Å,
Further, there is provided a gas separation apparatus characterized in that a porous silica membrane having a pore diameter of 2 to 10 ° is formed as the separation membrane on the small pore side of the porous support. Second, the porous silica film is mainly composed of the following general formula (I)

Embedded image (Wherein, R represents an alkyl group, n and m each represent a molar ratio, and n: m = 100: 0 to 30:70). The gas separation device according to the first aspect, which is a porous silica membrane obtained by using the gas separation device, is provided. Third, the porous support was provided with an oxide, nitride, or carbide ceramic coating on the outermost surface on the porous silica separation membrane side by a CVD method, a vacuum evaporation method, an ion plating method, or a sputtering method. A gas separation device according to the first aspect is provided. Fourth, the porous support is a metal porous support, and the outermost surface of the porous silica separation membrane side is a molten aluminum plating method, an ion plating method,
An aluminum film is formed by a vacuum deposition method or pressure bonding, and the film is anodized to form an aluminum film.
The gas separation device according to the first aspect, wherein pores of about 200 ° are formed.

That is, the gas separation device of the present invention provides a porous support comprising at least two layers of a layer having pores having a diameter of 10 ° to 400 ° and a layer having pores having a diameter of 400 ° to less than 100000 °. And a porous membrane having a pore diameter of 2 as a separation membrane on the small pore side of the porous support.
According to the gas separation apparatus, a high heat resistance and a high gas permeation rate are obtained by forming a porous silica membrane of 10 ° and utilizing the molecular sieving action of the porous silica separation membrane. And high gas selectivity can be achieved. In particular, when the porous silica film is a porous silica film obtained by using a polysilazane solution having a skeleton comprising a structural unit represented by the general formula (I), or the porous support is The outermost surface on the porous silica separation membrane side, a ceramic coating is applied by a CVD method or the like, or the porous support is made of metal,
An aluminum coating is formed on the outermost surface of the porous silica separation membrane by an aluminum plating method or the like, and pores of 10 to 200 ° are formed on the surface by anodizing the coating. A more uniform silica membrane is formed and higher gas selectivity can be achieved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. When the gas separation device of the present invention comprises, for example, a single-tube separator, it has a structure as shown in, for example, the overall view of FIG. 1 and the enlarged view of the membrane portion of FIG. In FIG. 1, 1 is a gas separation device, 2 porous supports,
(3) an inner layer (on the downstream side of the separation gas) of the support; (4) a surface layer (on the upstream side of the separation gas) of the support; (5) a silica membrane having pores made of polysilazane;
Denotes a source gas introduction pipe, 7 denotes a separation gas discharge pipe, and 8 denotes a non-separation gas discharge pipe. In FIG. 1, the support 2 has a two-layer structure including an inner layer 3 and a surface layer 4.
It can have a configuration of more than layers.

In FIGS. 1 and 2, a part of the raw material gas introduced from the introduction pipe 6 passes through the pores of the silica film 5 and then passes through the pores of the surface layer 4 and the inner layer 3 to be separated. The gas is discharged from the separation gas discharge pipe 7 as gas. On the other hand, the gas of large molecules that cannot pass through the pores of the silica membrane is discharged from the non-separable gas discharge pipe 8 as a non-separable gas. In addition,
In FIGS. 1 and 2, five silica membranes are arranged on the upstream side of the separation gas. However, a structure in which the silica membrane 5 is arranged on the downstream side may be adopted.

[0010] The gas separation apparatus using a separation membrane provided on a porous support according to the present invention has a pore diameter of 2 to 1 as a separation membrane.
The first feature is that a porous silica membrane having 0 ° pores is used. Preferred as the porous silica film used in the present invention is a silica film having the above pores obtained from polysilazane, particularly in Raman analysis,
A three-membered ring (600 ± 20 cm ^-1 ) and a four-membered ring (490 ± 20
cm ^-1 ), and a porous silica film having a (3-membered ring) / (4-membered ring) intensity ratio of 0.1 to 10.0 is preferable.

The above-mentioned porous silica film is mainly composed of, for example, a small ring having 4 or less member rings as shown by the following structural formulas (1) and (2). Compared with those having a main component, the hydrogen selectivity increases as the component has a small ring as a main component. In other words, this porous silica membrane has a pore size on the order of 、, and also has high heat resistance,
It has a high gas permeation rate and high gas separation performance (particularly hydrogen separation performance).

[0012]

Embedded image

[0013]

Embedded image

The porous silica film having a multi-membered ring structure is mainly composed of, for example, the following general formula (I)

Embedded image (Wherein, R represents an alkyl group, n and m each represent a molar ratio, and n: m = 100: 0 to 30:70). After dissolving in an organic solvent having a boiling point of 200 ° C. or lower to prepare a solution having a polysilazane concentration of 0.01 to 30% by weight, coating the solution on a porous ceramic or metal substrate having open pores 1 to 50 times. Obtained by

Further, in the gas separation apparatus according to the present invention, the porous support has a pore size of 10 to 10 m on the surface side on which a porous silica membrane having pores of 2 to 10 m having a thickness of 100 to 10000 m is formed.
Surface layer having pores of 400 to 400 ° and 400 to 1 on the inner side.
It is characterized by comprising at least two layers having pores of 00000 °, preferably 400 to 10,000 °. The thickness of the surface layer is in the range of 0.1 to 100 μm, preferably 0.1 to 10 μm, and the thickness of the inner layer is 0.1 to 100 μm.
１００100 mm, preferably 0.5〜１０10 mm.

By using a support having both an inner layer and a surface layer having a specific pore size distribution on the porous silica membrane side, a porous silica membrane having pores of 2 to 10 ° can be obtained.
It can be formed without cracks and pinholes,
High gas separation performance can be obtained with good reproducibility. In addition, by using such a support, the thickness of the porous silica layer can be reduced to 100 to 10000 °, and the length through which the target separation gas passes can be reduced. Speed can be realized. That is, the pore size distribution and the film thickness of the porous silica membrane are appropriately maintained, and high gas separation performance and high gas permeation rate can be simultaneously exhibited.

As the material of the porous support, alumina,
Ceramics such as zirconia and magnesia, metals such as aluminum and nickel, and various alloys such as stainless steel, inconel and hastelloy are arbitrarily used. However,
As described above, the porous silica membrane side (the outermost layer) has a pore size of 1
The surface layer having pores of 0 to 400 ° has a thickness of 0.1 to 1
It is necessary that the layer has a thickness of from 0.1 to 100 mm, preferably from 0.1 to 10 μm. , Preferably in the range of 0.5 to 10 mm. The ease of gas passage is proportional to the reciprocal of the pore diameter of the layer in each layer having no molecular sieve action other than the porous silica layer, is proportional to the layer thickness, and is determined by the balance between the two. The smaller the pores of the layer, the more difficult it is to pass, but the smaller the thickness of the layer, the less the effect.

When the pore diameter of the outermost layer is less than 10 °,
If the gas permeation rate is reduced, and if it exceeds 400 °, cracks and pinholes are generated in the porous silica membrane, pores larger than the desired 2 to 10 ° pores are formed, and the molecules are larger than the separation gas. High gas separation performance cannot be obtained by permeating non-separated gas. Since the innermost layer is thicker than the outermost layer and has a thickness of 0.1 to 100 mm, when the pore diameter is less than 400 °, the gas permeation rate is reduced. The function as a structural material for keeping the membrane stable against external force is reduced.

As a ceramic porous support such as alumina, for example, a pore diameter of 0.1 to 1 μm and a thickness of 1 to 3 mm
Of the innermost layer porous support and a pore diameter of 400 to 80
0Å, a two-layer ceramic support consisting of a porous layer having a thickness of 10 to 30 μm as a base material, and further forming an oxide, nitride, carbide ceramic by CVD, vacuum deposition, ion plating or sputtering. Etc. (pore diameter 10 ~ 200mm, thickness 0.1 ~ 0.2μm)
Those provided with are particularly preferred. With such a configuration, both high gas separation performance and high gas permeation speed can be achieved.

Further, as a metal porous support such as stainless steel, for example, a pore diameter of 1 to 10 μm and a thickness of 1 to 3 mm
On the innermost metal porous support, a 5-30 μm-thick aluminum coating is applied by a hot-dip aluminum plating method, an ion plating method, a vacuum evaporation method or pressure bonding, and the coating is further anodized. Diameter 10-20
Those having pores of 0 ° are particularly preferred. With such a configuration, both high gas separation performance and high gas permeation speed can be achieved.

The anodic oxidation treatment of aluminum is a technique capable of forming a columnar oxide film having a hollow center at the center by electrochemically oxidizing the surface of aluminum, and is capable of hardening, coloring, and imparting wear resistance to the surface. Will be possible. The pore diameter can be controlled by adjusting the processing conditions of the voltage and current and adjusting the electrolytic solution. When the anodic oxidation is interrupted and restarted, an oxide film smaller than the initial pore diameter is formed, and pores of 100 ° or less are obtained.

In order to form the porous silica film on the porous ceramic or metal support, first, the polysilazane is dissolved in an organic solvent to prepare a coating solution. As an organic solvent, the solvent dries slowly and penetrates into the porous material, making it difficult to form a uniform film. After dipping, the film thickness becomes uneven due to sagging when pulled up. In order to avoid such problems, those having a boiling point of 200 ° C. or less are used, and examples thereof include aromatic compounds such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, and triethylbenzene, and cyclohexene and cyclohexane. .

As a method of dissolving polysilazane in the above-mentioned solvent, any method can be adopted. In general, a method of adding the above-mentioned solvent to polysilazane and simply stirring is adopted. Since polysilazane easily reacts with water, it is necessary to remove water from the solvent by adding molecular sieve or the like before use. The water content of the solvent is preferably 1000 ppm or less. The temperature at which the polysilazane is dissolved in the solvent is not particularly limited, but is generally from the freezing point to the boiling point of the solvent. The atmosphere in which the dissolution is performed is not particularly limited, but a dry air or dry nitrogen atmosphere is preferable because polysilazane easily reacts with moisture.

The solution obtained by dissolving the polysilazane in the above solvent can be used as it is as a coating solution.
Pd, Ni, V, A as a catalyst for lowering the silica conversion temperature
g, Au, Pt, Rh, Ru, Ir, La, Co, Cu
It is very preferable to add at least one of these.

After dissolving the polysilazane, the concentration is 0.01 to 3
It is adjusted to 0% by weight, preferably 0.1 to 5% by weight (particularly preferably 0.1 to 2% by weight). The solution concentration of polysilazane (concentration of the coating solution) is proportional to the thickness of the formed coating film. When the solution concentration is reduced, the hydrogen permeability increases and the porous silica membrane has extremely high hydrogen separation performance. Is obtained. The concentration of the polysilazane coating solution is 0.01% by weight
If it is less than 1, a dense membrane cannot be obtained, and the hydrogen selectivity decreases. Conversely, if it exceeds 30% by weight, it exceeds the film thickness limit.
Cracks, pinholes, etc. occur in the film, and the hydrogen selectivity decreases. Further, only a low hydrogen permeation rate can be obtained.

The substrate on which the polysilazane solution adjusted to the above concentration is coated may be either a porous ceramic having continuous vents or a metal. However, since the polysilazane solution has a very low viscosity, when coating a porous ceramic substrate, it may be difficult to obtain a uniform porous silica film due to the permeation of the polysilazane into the substrate. TiN, SiC,
It is highly preferred to coat with Al ₂ O ₃ , SiO ₂ , SiN and the like.

As a means for coating the polysilazane solution on the substrate, a usual coating method, for example, spin coating, dip coating, flow coating, roll coating and the like are used. In addition, the number of coating times is 1 to 50 times,
Preferably it is 2 to 20 times. When the concentration is low, it is better to increase the number of coatings, and when the concentration is high, the number of coatings is smaller. The appropriate values for the hydrogen permeation rate and hydrogen selectivity [hydrogen permeation rate = 10 ^-8 to 10 ^-5 m ³ / (m ²
sec kPa), hydrogen / methane transmittance ratio = 30 to 10
00] is obtained. Specifically, 30% at 0.05% by weight.
In the case of 2% by weight, about 3 times is preferable.

In the gas separation apparatus using a separation membrane provided on a porous support according to the present invention, the separation membrane has a pore size on the order of Å, high heat resistance, and a high gas permeation rate (particularly, hydrogen permeation rate). And high gas separation performance (particularly hydrogen selectivity)
Is useful not only for the recovery of hydrogen-enriched gas from hydrogen-containing gas from petroleum refining plants and ammonia synthesis plants, but also for the removal of hydrogen produced in steam reforming processes and dehydrogenation reactions It is.

[0029]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the technical scope of the present invention.

Reference Example 1 [Synthesis of organopolysilazane] A 1-liter reaction vessel installed in a reaction vessel at a temperature of 0 ° C. was replaced with dry nitrogen, and then 500 ml of dry pyridine was added and maintained until the temperature became constant. . afterwards,
With stirring, dichlorosilane (SiH ₂ Cl ₂ ) 50.
5 g, methyldichlorosilane (MeSiHCl ₂ ) 2
8.75 g of each was added to form a complex mixture, and a white solid adduct was obtained.

Next, 32.0 g of dry ammonia was added over about 30 minutes while stirring the reaction mixture. After completion of the reaction, dry nitrogen is blown to remove unreacted ammonia,
Subsequently, the mixture was filtered under pressure under a nitrogen atmosphere to obtain 450 ml of a filtrate. To the filtrate was added 1000 ml of dry m-xylene, and the solvent was removed under reduced pressure.
0 g of a colorless viscous liquid methylated polysilazane was obtained. The number average molecular weight of this viscous liquid was 1500 as measured by GPC.

Example 1 First, the effect of the pore diameter on the outermost surface of the porous silica membrane when an alumina porous tube was used as the porous support was examined. The alumina porous tube as the base tube has a porous inner diameter of 7 mm of the inner layer.
φ, outer diameter 10 mmφ, pore diameter 1 mm, and the outermost outer layer has a two-layer structure in which a porous layer having a pore diameter of 300 to 800 ° is formed. A TiN layer having a thickness of 0.2 μm was formed as a surface layer on the outermost outer layer of the porous tube by a CVD method. The pore diameter of this TiN layer is 100 to 200 °.

The organopolysilazane obtained in Reference Example 1 was dissolved in xylene to prepare a coating solution having a concentration of 1.5% by weight. Next, the undercoated base tube was dipped in the coating solution, and the coating operation was repeated four times, followed by firing at 250 ° C. to obtain a base tube with a porous silica film.

Using the obtained base tube with a porous silica film, the transmittance of each gas of hydrogen and methane was measured. The measurement was performed using the separation device shown in FIG. For the measurement,
Pure gases of H ₂ and CH ₄ were used. Table 1 shows the results.

The gas permeability is defined by the following equation (1).

Q = F / (A · ΔP) (1) where Q is a gas permeability (m ³ / m ² · sec · kPa),
F is the gas permeation flow rate (m ³ / sec), A is the membrane area (m ² ), and ΔP is the differential pressure (kPa) upstream and downstream of the membrane. The transmittance ratio, which is an index of gas separation performance, is expressed as the ratio of the permeation speed of each gas. For example, H ₂ / CH ₄
Transmittance ratio beta _{H2 / CH4} of is defined by the following equation (2).

[ _Expression 2] _{βH2 / CH4} = _QH2 / _QCH4 (2)

COMPARATIVE EXAMPLE 1 Using a gas separator having the same porous alumina tube as the outermost layer having a pore diameter of the outermost layer of 300 to 800 °, the gas permeability of the gas separator and the gas transmission coefficient of H ₂ / CH ₄ were determined. Was measured in the same manner as in Example 1. Table 1 shows the results.

COMPARATIVE EXAMPLE 2 On the outermost surface layer of the alumina porous tube used in Comparative Example 1, a Ti having a pore size of 100 to 200 °
A gas separator in which N was formed to a thickness of 0.2 μm by a CVD method was used. The gas separation device corresponds to the device of Example 1 without a porous silica membrane. Gas permeability and H of the separator
₂ / CH ₄ transmittance ratio Gas separation coefficient was measured in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 A porous silica film was formed on the outermost surface layer of the alumina porous tube used in Comparative Example 1 without the TiN layer having a pore diameter of 100 to 200 ° in Comparative Example 2 in the same manner as in Example 1. A gas separation device was used. The gas separation device has a pore diameter of 300 to
The porous silica film is formed on the 800-degree surface layer, and corresponds to the apparatus of Example 1 having no TiN layer having a pore diameter of 100 to 200 degrees. Gas permeability and H of the gas separator
₂ / CH ₄ transmittance ratio Gas separation coefficient was measured in the same manner as in Example 1. Table 1 shows the results.

[0039]

[Table 1] Note) Measurement temperature: room temperature

From Comparative Examples 1 and 2 in Table 1, the larger the pore diameter of the gas separation device, the higher the permeation speed but the lower the transmittance ratio. When the pore diameter is larger than 100 °, only a low transmittance ratio can be obtained even if the permeation speed is high, and it does not function as a gas separation device. On the other hand, in Example 1, which is the structure of the present invention, in which the pore diameter of the underlying outermost surface layer of the porous silica film made of organopolysilazane is 100 to 200 °, the hydrogen / methane transmittance ratio also exceeds 30, and the molecular Alternatively, a high gas permeability ratio and a high hydrogen permeation rate can be obtained at the same time. In Comparative Example 3, a porous silica layer used in the present invention was formed on Comparative Example 1, but a high hydrogen permeability ratio could not be obtained. In Comparative Example 3, the pore diameter of the outermost surface layer of the alumina porous tube as the base was as large as 300 to 800 °, and a dense porous silica film could not be formed due to generation of cracks and pinholes. In other words, it can be seen that the structure of the present invention can provide a gas separation device having high gas permeability and high permeation speed.

Example 2 A coating operation was performed in the same manner as in Example 1 except that a coating solution having a concentration of 0.1% by weight with respect to the undercoated base tube was used.
A gas separator with a porous silica membrane was prepared in the same manner as in Example 1, except that the process was repeated twice.

Example 3 As a porous support (substrate tube) shown in Example 2, a stainless steel (SUS316) metal porous tube having a pore diameter of 10,000 ° was used. The metal porous tube as the base tube has an inner diameter of 7 mm.
φ, outer diameter 10 mmφ, pore diameter 1 μm, T 2 μm thick on the outermost layer surface, that is, the outermost surface on the porous silica film side
An iN layer was formed in the same manner as in Example 1, and a porous silica layer was formed thereon in the same manner as in Example 2, to obtain a gas separation device.

Example 4 An aluminum layer was formed to a thickness of 10 μm on the metal porous tube of Example 3 by hot-dip aluminum plating, and a porous silica layer was formed on a porous support obtained by anodizing the same as in Example 2. To obtain a gas separation device.

The gas permeability of the gas separators of Examples 1, 2, 3 and 4 was measured. Table 2 shows the results. Table 2
Therefore, in all of Examples 1 to 4, the transmittance increases as the temperature rises, and shows an activated diffusion behavior, and the H ₂ / CH ₄ transmittance ratio exceeds 30 in all cases, and molecular sieves appear. You can see that it is doing.

[0045]

[Table 2]

[0046]

According to a first aspect of the present invention, there is provided a gas separation apparatus using a separation membrane provided on a porous support.
The porous support comprises at least two layers: a layer having pores having a diameter of 10 ° or more and less than 400 ° and a layer having pores having a diameter of 400 ° or more and less than 100000 °, and the above-mentioned separation is performed on the small pore side of the porous support. Pore size 2-10 as membrane
Since the porous silica membrane of Å was formed, the molecular sieving action of the silica membrane was fully utilized. According to the separation apparatus, high heat resistance and high gas permeation rate (particularly, Hydrogen permeation rate) and high gas separation performance (particularly hydrogen selectivity).

The gas separation apparatus according to claims 2 to 4, wherein the porous silica membrane is obtained by using a polysilazane solution having a skeleton mainly composed of the structural unit represented by the general formula (I). Membrane, or the porous support is a ceramic porous support, and an oxide, nitride, or carbide ceramic coating is formed on the outermost surface of the porous silica separation membrane side by a CVD method, a vacuum evaporation method, Either a plating method or a sputtering method, or the porous support is a metal porous support, and the outermost surface of the porous silica separation membrane side is a molten aluminum plating method, an ion plating method. An aluminum coating is formed by vacuum deposition or pressure bonding, and the coating is anodized to form pores of 10 to 200 ° on the surface. Since the more homogeneous silica film is formed, it is possible to achieve higher hydrogen selectivity.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a configuration of an example of a gas separation device of the present invention.

FIG. 2 is a schematic structural view of a membrane portion of an example of the gas separation device of the present invention.

FIG. 3 is an explanatory view of a separation device for measuring gas permeability used in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas separation apparatus 2 Porous support 3 Inner layer of porous support 4 Surface layer of porous support 5 Porous silica membrane 6 Source gas introduction pipe 7 Separation gas outlet 8 Non-separation gas discharge pipe

Claims (4)

[Claims] 1. A gas separation apparatus using a separation membrane provided on a porous support, wherein the porous support has a diameter of 10 mm.
A layer having pores of not less than 400 ° and a diameter of not less than 400 ° 1
A porous silica membrane having a pore diameter of 2 to 10 mm as the separation membrane on the small pore side of the porous support, comprising at least two layers including a layer having pores of less than 00000 °. Gas separation equipment. 2. The porous silica film mainly comprises the following general formula (I): (Wherein, R represents an alkyl group, n and m each represent a molar ratio, and n: m = 100: 0 to 30:70). The gas separation device according to claim 1, wherein the gas separation device is a porous silica membrane obtained by using the same. 3. The porous support is provided with an oxide, nitride, or carbide ceramic coating on the outermost surface of the porous silica separation membrane by a CVD method, a vacuum deposition method, an ion plating method, or a sputtering method. The gas separation device according to claim 1, wherein 4. The porous support is a metal porous support, and an aluminum coating is formed on the outermost surface of the porous silica separation membrane by a hot-dip aluminum plating method, an ion plating method, a vacuum deposition method, or pressure bonding. 2. The gas separation device according to claim 1, wherein the film is formed and anodized to form pores of 10 to 200 [deg.] On the surface.