JP2002066271A - Gas separating filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas separating filter of an elongated length which can keep high gas separating efficiency in the longitudinal direction. SOLUTION: The gas separating filter 1 consisting of an elongated porous pipe and in which the inner diameter r1 of one end (a) is different from that r2 of the other end and/or the outer diameter R1 of one end is different from that R2 of the other end (b) is prepared.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas separation filter for separating a specific gas from a gas to be treated containing a plurality of types of gases, and more particularly, to improving the gas separation efficiency over the entire length direction of the filter. The present invention relates to a gas separation filter.

[0002]

2. Description of the Related Art Conventionally, a gas separation membrane and a gas separation membrane module provided with a separation filter capable of selectively transmitting and separating only specific components from a mixture containing a plurality of gases and vapors have been known as a gas separation membrane. As such a separation filter, an organic material such as a polymer resin, a metal film, or an inorganic oxide is used.

Conventionally, the general shape of this type of separation filter is disclosed in JP-A-11-226370 and JP-A-11-226370.
As described in JP-A-57423 and JP-A-6-191802, the filter has a cylindrical shape that is long in the longitudinal direction. For example, a gas to be treated is introduced into the inside of the filter from one end of the tubular filter, and the filter wall surface is formed. A specific gas is selectively transmitted from the inner surface to the outer surface through the filter, and the remaining gas is discharged from the other end of the filter to separate the specific gas.

[0004]

However, in the case of a cylindrical filter having a long length in the longitudinal direction as described above, the flow rate of the gas to be treated is large and the linear velocity is large near the gas introduction portion, that is, upstream of the filter. Therefore, although having high gas separation characteristics due to the turbulent flow effect, the gas flow rate decreases downstream of the filter that discharges the remaining gas,
There is a problem that the gas flow becomes laminar and the concentration of the specific gas to be separated is low, so that the gas separation characteristics deteriorate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to maintain a gas separation performance in a longitudinal direction of a gas separation filter and to improve a gas separation efficiency as a whole filter. It is to provide a separation filter.

[0006]

The present inventor has studied the structure of a gas separation filter for the above-mentioned problems,
By making the shape of the both ends of the porous tube forming the gas introduction part and the discharge part different from each other, and making the volume (cross-sectional area) of the gas passage on the gas discharge side smaller than that on the gas introduction side It has been found that a turbulent flow can be generated on the downstream side of the filter, and the gas separation performance can be maintained as a whole without lowering the gas separation efficiency on the downstream side. As a result, the gas separation efficiency can be improved as a whole filter.

That is, the gas separation filter of the present invention comprises:
It is made of a long porous tube, and the inside diameter of one end of the gas separation filter is different from the inside diameter of the other end, and / or the outside diameter of one end of the gas separation filter is the outside diameter of the other end. It is characterized by being different.

Here, the inside diameter and / or the outside diameter of the gas separation filter changes continuously or stepwise from one end to the other end, and the inside diameter of the one end of the gas separation filter is 0.1 mm. 5 to 50 mm, the inner diameter of the other end is 0.1 to 10 mm, the outer diameter of the one end of the gas separation filter is 0.5 to 70 mm, and the outer diameter of the other end is 0.3 to 50 mm. Desirably.

The porous tube is made of an inorganic porous material, and the porous tube is provided with a porous support, and a separation membrane formed on an inner surface or an outer surface of the porous support. Preferably, an intermediate layer is provided between the porous support and the separation membrane, and the thickness of one end of the intermediate layer is different from the thickness of the other end.

Further, it is preferable that a plurality of the gas separation filters are arranged so that the central axes of the porous tubes are parallel to each other and converge.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view showing an example of a gas separation filter according to the present invention. According to FIG. 1, a gas separation filter (hereinafter simply referred to as a filter tube)
Reference numeral 1 denotes a structure in which an intermediate layer 3 and a gas separation membrane (hereinafter simply referred to as a separation membrane) 4 are sequentially formed on an inner wall surface of a long porous support pipe (hereinafter simply referred to as a support pipe) 2. Consists of

The support tube 2 has, for example, a porosity of 20 to 40.
%, Having a large number of pores having an average pore diameter of 0.05 to 2 μm,
It is desirable that it be made of an inorganic porous material such as α-alumina, cordierite, silicon nitride and the like.

As the separation membrane 4, an organic polymer membrane or a metal thin film can be used. However, in terms of gas separation performance, heat resistance and chemical resistance, inorganic porous materials such as alumina, titania, zirconia, silica, etc. It is desirable to use amorphous alumina or silica because the pore diameter can be easily controlled, and it is also desirable to use amorphous silica having a siloxane bond capable of controlling the pore diameter to 1.0 nm or less. From the viewpoint of improving the heat resistance and the water resistance of the separation membrane 4, silica containing zirconia is desirable. In addition, the average pore diameter of the separation membrane 4 is selected from the viewpoint of selective permeation performance of a specific gas.
For example, 0.3 to 1.0 nm, particularly 0.4 to 0.7 nm
It is desirable that

As the intermediate layer 3, an organic polymer membrane can be used. However, inorganic porous materials such as alumina, titania, zirconia, and silica are particularly preferable in terms of gas separation performance, heat resistance, and chemical resistance. It is desirable to use amorphous alumina or silica from the viewpoint that the pore diameter can be controlled.
Alumina is optimal.

The intermediate layer 3 is used to increase the film-forming property of the separation membrane 4 on the support tube 2 to reduce the thickness of the separation membrane 4 and increase the gas permeation rate to achieve high gas separation performance. Although it is formed, the pore diameter of the intermediate layer 3 is desirably between the pore diameter of the support tube 2 and the pore diameter of the separation membrane 4. 1 μm or less,
It is particularly desirable that the thickness be 1 to 10 nm.

According to the present invention, a major feature is that the inside diameter of one end of the filter tube 1 is different from the inside diameter of the other end.
According to FIG. 1, an end b which is one end of the gas separation filter 1
Is formed so that the inner diameter on the side is larger than the inner diameter on the end a side which is the other end.

Thus, the specific surface area of the separation membrane 4 can be increased, and the end a of the gas separation filter 1 can be increased.
When the gas to be treated is introduced from the side to the inner surface side of the gas separation filter 1, the specific surface area of the separation membrane 4 on the end a side which is the upstream side of the filter tube 1 can be increased, and the gas separation efficiency on the upstream side can be increased. At the same time, the flow of the gas to be treated is made turbulent on the downstream end b, so that the gas separation efficiency on the downstream side can be increased, and the gas separation efficiency of the entire filter tube 1 can be increased.

According to FIG. 1, the inner diameter of the filter tube 1 is made different by changing the thickness (film thickness) of the intermediate layer 3 among the support tube 2, the intermediate layer 3, and the separation membrane 4.
Specifically, the thickness of the intermediate layer 3 is larger at the end b than at the end a.
The side is formed to be thick.

According to FIG. 1, the thickness of the intermediate layer 3 is
It is formed so as to be continuously thicker from the end a to the end b, whereby the turbulent state of the gas to be processed can be efficiently maintained without obstructing the flow of the gas to be processed. . The thickness of the intermediate layer 3 ranges from the end a to the end b.
It may be formed so as to be continuously thicker toward the side, but is preferably formed stepwise in order to efficiently generate a turbulent state.

According to the present invention, in addition to changing the thickness of the end portion a and end b of the intermediate layer 3 as shown in FIG.
It is also possible to change the thickness of the end portions a and b of the separation membrane 4 so that the thickness of the filter tube 1 as a whole is different between the ends a and b. In particular, the method of changing the thickness of the intermediate layer 3 as shown in FIG. 1 is optimal in terms of improvement of gas separation performance, easiness of manufacture, and improvement of mechanical reliability such as strength of the filter tube 1 as a whole.

Further, the intermediate layer 3 is formed of a plurality of intermediate layers having different pore diameters, and these intermediate layers are formed in a predetermined length region from one end of the support tube 2 in order from the one having a large pore diameter. The formation length of the layer can be changed stepwise.

Here, the support tube 2 has, for example, an outer diameter of 0.1 mm.
3 to 70 mm, especially 0.5 to 30 mm, further 1 to 10
mm, the thickness is 0.1 to 10 m
m, preferably 0.3 to 2 mm. Also,
The thickness of the separation membrane 4 is determined in terms of gas separation efficiency and preventing cracks and pinholes from being generated in the separation membrane 4.
It is preferably from 0.01 to 10 μm, particularly preferably from 0.1 to 1 μm.

Further, the thickness of the intermediate layer 3 is, for example, 0.001 to 10 mm, particularly 0.001 to 1 m at the end a side.
m, the end b side is 0.01 to 20 mm, particularly 0.05 to 2
mm, so that the inner diameter of the filter tube 1 on the end a side is 0.5 to 50 mm, particularly 1 to 10 mm.
mm, the inner diameter on the side of the end b is 0.1 to 10 mm, particularly 0.1 mm.
Desirably, it is 1 to 5 mm.

The length of the filter tube 1 is desirably 10 to 1000 mm, particularly 100 to 500 mm, in order to improve the gas separation performance and maintain a strength that does not hinder handling.

A method of separating a specific gas that can be separated by the separation membrane 4 from a gas to be treated composed of a plurality of types of mixed gas by using the filter tube 1 of FIG. The gas to be treated is introduced into the tube from the column, and is brought into contact with the separation membrane 4 to selectively permeate only the specific gas from the mixed gas to pass through the intermediate layer 3 and the support tube 2 from the side of the filter tube 1. It is led out. The remaining gas that is not permeated by the separation membrane 4 among the gases to be treated is the filter tube 1.
Flows toward the end b side, and is finally discharged out of the filter pipe 1 from the end b side.

According to the present invention, as described above, since the flow of the gas to be treated flowing on the inner surface side of the filter tube 1 can be maintained in a turbulent state regardless of the length direction, the gas separation efficiency of the filter tube 1 as a whole can be maintained. Is improved.

Further, in FIG. 1, the filter tube 1 is formed by the support tube 2, the intermediate layer 3, and the separation membrane 4.
The present invention is not limited to this, and may be one in which the intermediate layer 3 is not formed and the separation membrane 4 is directly formed on the surface of the support tube 2, and further, the support tube 2 is not provided. Alternatively, it may be formed as the separation membrane 4 alone.

In FIG. 1, the intermediate layer 3 and the separation membrane 4 are formed on the inner surface of the support tube 2.
The intermediate layer 3 and the separation membrane 4 may be formed on the outer surface of the above. In this case, the inner diameter at the end a of the support tube 2 is adjusted to be larger than the inner diameter at the end b.

In the filter tube 1 shown in FIG. 1, the thickness of at least one of the support tube 2, the intermediate layer 3 and the separation membrane 4, which are formed as a single unit, is changed so that the filter tube 1 is formed.
However, the present invention is not limited to this, and a plurality of short filter tubes having different inner diameters and having different lengths may be joined.

FIG. 2 is a schematic sectional view showing a second embodiment of the gas separation filter according to the present invention, in which a plurality of short filter tubes having different inner diameters and lengths are joined. According to FIG. 2, the filter tube 6 has the same configuration as the above-described filter tube 1 except that the thickness of the intermediate layer is the same in the length direction and the length of the tube is short. It has a configuration in which a plurality of filter tubes having different inner diameters of the tube 7 and the filter tube 8) are connected in series.

According to FIG. 2, by making the inner diameter of the support tube 10 of the filter tube 7 larger than the inner diameter of the support tube 11 of the filter tube 8, the inner diameter of the filter tube 7 becomes larger than the inner diameter of the filter tube 8. It is formed to be large.
Further, according to FIG. 2, the outer diameter is made the same by changing the thickness of the support tube 10 and the support tube 11, but the outer diameter may be changed while the thickness is kept constant, or may be adjusted appropriately. Further, between the filter tube 7 and the filter tube 8, the ends thereof are bonded with an adhesive 12.
Connected by gluing.

According to the present invention, the gas to be treated is introduced from the end of the filter tube 6 of FIG. 2 on the filter tube 7 side to the inner surface of the filter tube 6 (filter tube 7), and the gas is filtered while performing gas separation. By introducing the gas into the pipe 8, the turbulent flow of the gas can be promoted, and the gas separation efficiency on the filter pipe 8 side, which is on the downstream side, can be increased.

Further, according to FIG. 2, the filter tube 6 has two filter tubes 7 and 8 connected to each other, but the present invention is not limited to this. The above filter tubes may be connected in series. (Module) FIG. 3 shows a schematic cross-sectional view of an example of the gas separation module having the above-described filter tube of the present invention. According to FIG. 3, a gas separation module (hereinafter simply abbreviated as a module) 15 converges a plurality of the above-described filter tubes 1, and a filter converging body 17 having both ends supported by a support member 16 has a substantially cylindrical shape. The support member 16 is accommodated in the housing 18, and is fixed to the inner surface of the housing 18 via the sealing member 19. In addition,
According to FIG. 3, the inner surface of the housing 18 is divided into three regions by the support member 16 and the sealing member 19 and sealed.

The housing 18 has a gas inlet 20 for introducing a gas to be treated into the system (on the inner surface side of the housing 18) in a region A on the end a side of the filter tube 1.
A permeated gas outlet 21 for discharging the gas permeated by the separation membrane 4 out of the system is provided in the central region B of the filter tube 1.
Residual gas discharge ports 22 for discharging the non-permeated residual gas to the outside of the system are formed in the region C on the end b side of the filter tube 1 and in three regions.

In order to perform gas separation using the module 15 shown in FIG. 3, a gas to be treated is introduced into the region A on the inner surface side of the housing 18 from the gas introduction port 20 and the filter is passed through the end a of the filter tube 1. The gas is introduced into the inner surface of the tube 1 and permeates the specific gas from the inner surface to the outer surface in the filter tube 1, and the permeated gas passes through the permeated gas outlet 21 from the region B on the inner surface of the housing.
Through the module 15 to the outside. The residual gas that has passed through the inner surface of the filter tube 1 is led out from the end b of the filter tube 1 to the region C of the housing, and is discharged to the outside of the module 15 via the residual gas discharge port 22.

Further, in FIGS. 1 and 2, the inner diameters of both ends of the filter tube are made different, but the present invention is not limited to this, and the outer diameters of both ends of the filter tube are made different. The gas to be treated may be introduced into the outer surface of the filter tube.

FIG. 4 is a schematic sectional view of still another example of the gas separation filter of the present invention in which the outer diameter of the filter tube is different, and FIG. 4 is a schematic sectional view of a gas separation module having the gas separation filter. The figure is shown in FIG.

According to FIG. 4, the filter tube 25 is composed of a support tube 26, an intermediate layer 27 and a separation membrane 28 made of the above-mentioned materials. And a separation film 28 are sequentially formed.

According to FIG. 5, the module 30 comprises:
A plurality of filter tubes 25 are converged, and both ends thereof are
The filter converging body 31 supported by 6 is housed in a substantially cylindrical housing 32, and the support member 16 is fixed to the inner surface of the housing 32 via the sealing member 19. According to FIG. 3, the supporting member 16 and the sealing member 19
The inner surface of the housing 32 is divided into three regions D, E, and F, and is sealed.

The housing 32 has a gas inlet 33 for introducing a gas to be treated into the system (the inner surface of the housing 32).
Thus, the permeated gas discharge port 34 for discharging the gas permeated through the filter tube 25 to the outside of the system is provided in the filter tube 25.
The residual gas discharge port 35 for discharging the residual gas that is not permeated to the outside of the system from the end of the central region E of the filter tube 2.
5 are formed in the region F on the end b side.

In order to perform gas separation using the module 30 shown in FIG. 5, a gas to be treated is introduced into the region E of the housing 32 from the gas introduction port 33 and the end a of the outer surface of the filter tube 25 is introduced. Then, the specific gas is transmitted from the outer surface side to the inner surface side through the filter tube 25, and the permeated gas is discharged from the area F of the housing 32 to the outside of the module 30 through the permeated gas discharge port 35. The residual gas that has passed through the outer surface of the filter tube 25 is discharged outside the module 15 from the residual gas outlet 34 located on the end b side of the filter tube 25 in the region E of the housing 32.

According to the invention, the end b of the filter tube 25
Is characterized in that it is formed so that the outer diameter on the side is larger than the outer diameter on the side of the end portion a, whereby the gas to be treated is introduced into the outer surface side of the filter tube 25 as described above. Since the volume of the gas to be processed at the downstream end b is smaller than that at the upstream end a, turbulence can be promoted in the gas to be processed.

According to FIG. 4, the end b of the support tube 26
The inner diameter on the side is formed larger than the inner diameter on the end a side, whereby the permeated gas can be efficiently collected without obstructing the flow of the permeated gas.

In FIG. 4, the filter tube 25 is formed by the support tube 26, the intermediate layer 27, and the separation membrane 28. However, the present invention is not limited to this. The separation film 28 may be formed directly on the surface of the support tube 26 without being formed, or the separation film 28 may be formed without the support tube 26.

In FIG. 4, the intermediate layer 27 and the separation film 28 are formed on the outer surface of the support tube 26. However, the intermediate layer 27 and the separation film 28 are formed on the inner surface of the support tube 26. You may.

Further, as described above, the outer diameter of the filter tube desirably changes continuously or stepwise, and may be formed by a joined body of a plurality of filter tubes.

The gas separation filter according to the present invention is, for example, H ₂ , N ₂ , O ₂ , CO ₂ , He, Ar, H ₂ O, C
_{H 4, C 2 H 6,} C 3 H 8, methanol, ethanol, n-
A specific gas can be selectively separated from a mixed gas containing at least one kind of gas such as propanol, i-propanol (IPA), acetone, toluene, SF ₆ , NF ₃ , and a fluorine compound such as hydrofluorocarbon and perfluorocarbon. Things.

(Production Method) Next, an example of a method for producing the gas separation filter of the present invention will be described. First, for example, an average particle size of 0.05 to 10 μm, particularly 0.1 to 5 μm
After preparing a slurry by adding a predetermined amount of an organic binder, a lubricant, a plasticizer, a solvent, and the like to the alumina raw material of m, the slurry is formed into a cylindrical tube by a known forming method such as extrusion molding or injection molding. . Thereafter, the support tube having the same inner diameter and outer diameter can be produced by firing the formed tube at a predetermined temperature in an oxidizing atmosphere.

Next, a colloid or sol containing the above-mentioned metal oxide for forming an intermediate layer, or a suspension in which these powders are dispersed (hereinafter, abbreviated as a slurry for the intermediate layer) is used for the above-mentioned support. A coating of the slurry for the intermediate layer is formed on the inner surface of the tube.

As a specific method for forming the coating, the slurry for the intermediate layer is injected using a feed pump or a syringe (syringe), and the slurry is adhered to the inner wall surface of the support tube, and the remainder is discharged. The slurry is dried by dipping the support tube into the slurry while the outer surface of the support tube is covered with a polymer film or the like, and pulling the slurry to the inner wall surface of the support tube. Attached to
Although a method of drying is preferable, according to the present invention, the slurry for an intermediate layer is attached to the inner wall surface and the outer wall surface of the support tube in a state where the support tube is set upright, and the viscosity of the slurry is increased before the slurry is dried. The method of flowing the slurry by the method described above, and the formation of the coating film is performed a plurality of times, and the second and subsequent coating films are formed only in a predetermined length region from one end of the support tube, so that the intermediate layer is continuously or stepwise formed. The thickness can be changed.

Further, the slurry is applied to the outer wall surface of the support tube by dipping the support tube plugged at the end into the slurry and pulling it up, or by applying the slurry to the outer wall surface of the support tube. The thickness of the intermediate layer can be changed continuously or stepwise in the same manner as described above, and in particular, a filter tube having an outer diameter at one end and an outer diameter at the other end can be manufactured. Note that, as described above, for example, by changing the particle size of the intermediate layer forming raw material, a plurality of intermediate layers having different pore diameters may be formed only in a predetermined length region from one end of the support tube.

Further, in order to prevent gas leakage from the end of the support tube, it is preferable to form a sealing layer such as a glass frit on only the wall surfaces at both ends of the support tube. In this case, the sealing layer is formed without forming the separation film at the end of the filter. However, the inner diameter of both ends of the filter can be changed by changing the thickness of the sealing layer.

Then, the coating is subjected to a heat treatment in an oxidizing atmosphere, for example, at 350 to 900 ° C., particularly at 400 to 600 ° C. to form an intermediate layer having a continuously or stepwise varying thickness on the inner surface of the support tube. be able to. Also,
When coating is performed a plurality of times, a series of operations of coating, drying, and baking may be repeated.

On the other hand, in order to produce a separation membrane, for example, an alumina sol, a titania sol, a silica sol, a zirconia sol, etc. The sol is applied to the surface of the porous support tube.

As a method of forming the sol on the intermediate layer forming surface of the support tube, a method of injecting the sol using a liquid sending pump or a syringe (a syringe) as described above, A method in which the outer surface of the support tube is covered with a polymer film and immersed in the sol solution and pulled up, a method in which the support tube whose end is plugged in the sol solution is immersed and pulled up, A method of applying the slurry or the like can be adopted.

At this time, the thickness of the separation membrane can be changed by changing the amount of sol adhered in the same manner as in the method of forming the intermediate layer.

The sol thus formed is dried and gelled, and the sol is dried in the air at, for example, 350 to 900 ° C.
In particular, by performing heat treatment at 400 to 600 ° C., an inorganic separation membrane having pores of a predetermined pore diameter can be firmly formed on the surface of the intermediate layer.

In the filter tube forming method described above, the supporting tube is formed by using a columnar core made of an organic resin or the like having one end having a diameter larger than that of the other end, and forming the supporting tube on the surface thereof. A support tube in which the inside diameter of one end is larger than the inside diameter of the other end can also be produced by a method of applying a slurry for application, removing the core material and firing the mixture, or casting using a predetermined mold. .

The outer diameter at one end and the outer diameter at the other end can be made different by performing the above-mentioned casting or grinding the cylindrical support tube.

To join a plurality of filter tubes having a cylindrical shape as shown in FIG.
A plurality of cylindrical filter tubes having different inner diameters or outer diameters are produced by the above-described method, and an adhesive such as glass frit is applied to the ends of the filter tubes and bonded to each other, and heat treatment is performed if desired.

[0061]

(Example 1) First, a mixture of alumina having a purity of 99.9% and an average particle diameter of 0.1 μm, an organic binder, a lubricant, a plasticizer, and water was extruded to form a tube. After being formed into a body, it is fired at 1300 ° C. in the air, and is a support tube having an inner diameter of 2.0 mm, a wall thickness of 0.5 mm, and a support tube length of 320 mm. The average pore diameter is 0.2 μm and the porosity is 35%. An α-alumina porous support tube having the following formula was prepared.

Further, both ends of the alumina support tube are 10 m long.
Then, a glass paste was applied to the inner surface of m, and heat treatment was performed to form a sealing layer. The thickness of the sealing layer was adjusted to the same thickness as an intermediate layer described later.

On the other hand, a slurry obtained by highly dispersing γ-alumina powder having an average particle diameter of 0.1 μm in an aqueous solution of nitric acid using ultrasonic waves was used, and the outer surface of the alumina support pipe was coated with a polymer film. After covering, dipping to a position of 315 mm from the lower end and holding for 30 seconds, it was pulled up at a speed of 5 mm / second, dried at room temperature for 1 hour with the support tube set upright, and then baked at 500 ° C. for 1 hour. Next, the support tube was immersed up to a position 260 mm from the lower end, with the end on the same side facing down, pulled up, dried and fired as described above. Furthermore, similarly from the lower end, 210, 160, 110,
The height was changed stepwise to 60 mm, and an intermediate layer having a stepwise change in thickness was formed on the inner surface of the support tube.

On the other hand, an alkoxide of Si and an alcohol of Zr
Oxide is complexed in ethanol solvent and hydrolyzed
Made SiO_Two-ZrO_TwoForming an intermediate layer of the support tube with the sol
Immersed in the surface up to a position 315mm from the lower end of the support tube
Then, in the same manner as in the method of forming the intermediate layer, pull up, dry, and fire
Is repeated four times to obtain amorphous SiO 2_Two −
ZrO_TwoA filter tube on which a quality separation membrane was formed was fabricated.

The shape of both ends of the obtained filter tube was SEM
When measured by observation, the inner diameter of the filter tube at one end was 1.6 mm, the thickness of the intermediate layer was 0.2 mm, the thickness of the separation membrane was 0.2 μm, and the inner diameter of the filter tube at one end was 0.6 mm. Was 0.7 μm, and the thickness of the separation membrane was 0.2 μm.

A module shown in FIG. 3 was manufactured using a filter convergent body obtained by converging 37 obtained filter tubes, and H ₂ and N ₂ having the same volume ratio were passed through the gas inlet of the module. Was introduced under a pressure of 5 l / min to 0.1 MPa, and the concentration of H ₂ and N _{2 in} the gas permeated through the filter tube and discharged from the permeated gas outlet was measured by gas chromatography. As a result, the H ₂ concentration was 98.
% And N ₂ concentration were 2%, which was high H ₂ gas separation performance.

Comparative Example With respect to the filter tube of Example 1, the thickness of the intermediate layer in the length direction is the same, and the filter tube has an inner diameter of 2.0 mm and an outer diameter of 3.0 mm, which are constant in the length direction. Except for the above, a filter tube and a module were manufactured in the same manner as in Example 1.

The gas separation performance of N ₂ and H ₂ was evaluated for the obtained module in the same manner as in Example 1. As a result, the H ₂ concentration was 82% and the N ₂ concentration was 18%. The separation performance was lower than that of the separation module.

(Example 2) Compared to Example 1, the thickness of the intermediate layer was 0.1 mm, the thickness of the separation membrane was 0.2 μm, and the length was 160
2 mm cylindrical filter tube with an outer diameter of 3 mm and an inner diameter of 2
mm, an outer diameter of 2.5 mm, and an inner diameter of 0.8 mm, respectively, and a glass frit was applied to the ends to join the filter tubes.

A module shown in FIG. 5 was manufactured by using a filter converging body obtained by converging 37 obtained filter tubes, and the same mixed gas as in Example 1 was introduced from the gas inlet to be processed of the module. As a result of measuring the concentration of the gas discharged from the discharge port, the H ₂ concentration was 96% and the N ₂ concentration was 4%, which was high H ₂ gas separation performance.

[0071]

As described above in detail, according to the gas separation filter of the present invention, the shape of the both ends of the porous tube forming the gas introduction part and the discharge part to be treated is made different, and the gas flow on the remaining gas discharge side is made. By making the volume (cross-sectional area) of the passage smaller than that of the gas to be treated, a turbulent flow can be generated on the downstream side of the filter, and the gas as a whole can be generated without lowering the gas separation efficiency on the downstream side. As a result of maintaining the separation performance, the gas separation efficiency of the entire filter can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a gas separation filter of the present invention.

FIG. 2 is a schematic sectional view showing another example of the gas separation filter of the present invention.

FIG. 3 is a schematic sectional view showing an example of a gas separation module including the gas separation filter of FIG.

FIG. 4 is a schematic sectional view showing still another example of the gas separation filter of the present invention.

FIG. 5 is a schematic sectional view showing an example of a gas separation module including the gas separation filter of FIG.

[Explanation of symbols]

 1, 6, 7, 8, 25 Gas separation filter 2, 10, 11, 26 Porous support tube 3, 27 Intermediate layer 4, 28 Gas separation filter 12 Adhesive 16 Support member 17, 31 Convergent body 20, 33 Gas inlet 21, 35 Permeated gas outlet 22, 34 Remaining gas outlet

Claims (8)

[Claims] 1. A gas separation filter comprising a long porous tube, wherein the inside diameter of one end of the gas separation filter is different from the inside diameter of the other end, and / or the outside diameter of one end of the gas separation filter. Is different from the outer diameter of the other end. 2. The gas separation filter according to claim 1, wherein an inner diameter and / or an outer diameter of the gas separation filter changes continuously or stepwise from one end to the other end. 3. An inner diameter of the one end of the gas separation filter is 0.5 to 50 mm, and an inner diameter of the other end is 0.1 to 10 mm.
3. The gas separation filter according to claim 1, wherein 4. An outer diameter of said one end of said gas separation filter is 0.5 to 70 mm, and an outer diameter of said other end is 0.3 to 50 mm.
3. The gas separation filter according to claim 1, wherein 5. The gas separation filter according to claim 1, wherein said porous tube is made of an inorganic porous material. 6. The porous tube according to claim 1, wherein the porous tube comprises a porous support and a separation membrane formed on the inner or outer surface of the porous support. Gas separation filter. 7. The method according to claim 1, wherein the porous support and the separation membrane are provided between:
7. The gas separation filter according to claim 1, wherein an intermediate layer is provided, and the thickness of one end of the intermediate layer is different from the thickness of the other end. 8. The gas according to claim 1, wherein a plurality of the gas separation filters are arranged so that the central axes of the porous tubes are parallel to each other and converge. Separation filter.