JP3537909B2 - Method for producing ZSM-5 type zeolite membrane and liquid mixture separation membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a ZSM-5 type zeolite membrane and a liquid mixture separation membrane comprising a ZSM-5 type zeolite used for separating a specific liquid from a mixture of two or more liquids. It is about.

[0002]

BACKGROUND OF THE INVENTION The ability to separate a particular liquid from a liquid mixture by means of a non-porous polymer membrane is e.g.
U.S. Pat. No. 2,953,50 which discloses means for separating water and formaldehyde by means of an acrylic acid copolymer membrane
No. 4,035,291 which discloses means for separating water and alcohol in an azeotropic mixture state by a polyvinyl alcohol membrane.

The liquid separation means includes a pervaporation method for separating a specific liquid from a liquid mixture as a vapor, a vapor permeation method for separating a specific liquid in a vapor state from a liquid mixture, and the like. Attention has been paid to a new separation method for separating or concentrating a liquid mixture having a close boiling point and a small specific volatility, or a mixture containing a substance which undergoes polymerization or modification by heating. Cellulose acetate membranes and polyvinyl alcohol membranes (Japanese Unexamined Patent Publication No. Sho 59-1) have been used as mixed liquid separation membranes that have been put to practical use.
No. 09204) and a polyethyleneimine-based crosslinked film (JP-A-59-55305).

[0004] Other liquid mixture separation membranes include, for example, polyethylene, polypropylene, polyamide, polystyrene, or a copolymer membrane thereof, an ethylene-vinyl alcohol copolymer membrane for separating a water-alcohol mixture, and a polydimethylsiloxane membrane. Further, a membrane in which N-vinylpyrrolidone is graphitized on a microporous polytetrafluoroethylene membrane for separating a water-dioxane mixture is known.

[0005]

By the way, any of the known liquid mixture separation membranes always separates water by a membrane when separating water and an organic liquid. For this reason, when a small amount of organic liquid is present in a large amount of water, it is necessary to remove a large amount of water through a pervaporation membrane, and there is a problem that it cannot be said to be an efficient separation means.

Furthermore, the liquid mixture separation membranes described in the above-mentioned Japanese publications have low separation performance of substances having similar physical properties, particularly low methanol-water separation performance, and have a low DMF (N, N
-Dimethylformamide), the water-organic liquid mixture which can be separated has a higher carbon number than ethanol, that is, has a carbon number of 3 as a separable water-organic liquid mixture.
It can be used only for the above alcohols, ketones, etc.
There is a disadvantage that it is not practical.

The present inventor has noticed that zeolites having high heat resistance, solvent resistance, chemical resistance and the like can separate a specific liquid from a liquid mixture by adsorption, and find a zeolite having a separating performance for a specific mixed liquid. That
As a result of intensive studies on a method of forming a zeolite into a membrane in order to continuously perform a separation operation, the present invention has been completed.

That is, a first object of the present invention is to provide a method for producing a ZSM-5 type zeolite membrane. A second object of the present invention is to provide a liquid mixture separation membrane using a ZSM-5 type zeolite.

[0009]

In order to achieve the first object, the method for producing a ZSM-5 type zeolite membrane of the present invention comprises H ₂ O, Na ₂ O, SiO ₂ and tetrapropylammonium halide. The molar composition ratio of the components of (TPAX) is H ₂ O / Na ₂ O = 20-60, Na
₂ O / SiO ₂ = 1 or more, H ₂ O / ｛Na ₂ O + (TP
AX) to form the ₂ O} = 5 to 50 and the aluminosilicate gel, while retaining the aluminosilicate gel was immersed porous support to a temperature of 100 to 180 ° C., 3
Hydrothermal synthesis for ~ 6 hours to form a reaction product in the form of a film covering the surface of the porous support.
The reaction product is calcined for 2 to 48 hours.

The (TPAX) ₂ O is a reaction intermediate. The firing is intended to remove unreacted substances that cause pinholes and the like, in particular, tetrapropylammonium halide (TPAX). The hydrothermal synthesis is industrially preferably performed while stirring the aluminosilicate gel. However, when the reaction is carried out in a small scale or in a boiling state, the reaction can be favorably advanced without particularly stirring.

It is preferable that the above-mentioned hydrothermal synthesis is newly prepared for the reaction composition, and the above-mentioned hydrothermal synthesis and calcination are repeated a plurality of times, usually about 2 to 5 times. By laminating the membranes in this way, a good liquid mixture separation membrane can be formed on the porous support. Each of the above components can be supplied by silica sol: colloidal silica, sodium hydroxide, or the like.

The ZSM-5 type zeolite is, for example,
"Science and application of zeolites" edited by Kodansha Scientific Co., Ltd., January 1987, 2.2 Basic structural units and classification of zeolites, page 17, "Table 2.2 Typical molecular sieve zeolites" It is a conventionally known substance. When the activity of ZSM-5 type zeolite decreases, it can be recovered by firing.

If the component ratio during the hydrothermal synthesis is out of the above range, the reaction temperature is lower than the above, the reaction time is shorter than the above, or the number of times of the reaction is small, etc., no crystals are formed. However, there is a problem that a pinhole is formed, which is not preferable. When the reaction temperature is higher than the above range, the reaction time is longer than the above range, and the number of times of the reaction is more than the above range, the crystal becomes amorphous, and the function as a separation membrane (separation performance, permeation performance) is lost, which is preferable. Absent. Further, when the calcination temperature is lower than the above range and the calcination time is shorter than the above range, unreacted substances remain and the function as a membrane (separation performance and permeation performance) is undesirably lowered.

The film thickness obtained by the hydrothermal synthesis is usually in the range of about 3 to 100 μm. The porous support is not particularly limited. For example, a tube or plate made of a porous material such as alumina porous, metal, organic / inorganic polymer, and ceramics can be used. If the average pore size of the porous support is less than 0.05 μm, the permeation rate is too small to be practical. When the average pore diameter exceeds 10 μm, the selectivity decreases. On the other hand, if the porosity is less than 10%, the permeation rate is low, the selectivity exceeding 60% is reduced, and the strength as a support cannot be obtained. A preferred porous support has an average pore diameter of 0.
An alumina porous support having a pore size of 1 to 2 μm and a porosity of 30 to 50%.

The shape of the porous support is not particularly limited. Generally, a separation membrane used for the pervaporation method or the vapor permeation method has a pipe having an outer diameter of about 10 nm and a length of 20 to 100 cm. And the thickness is 0.2 to several mm, or the outer diameter is 30 mm.
It is preferable that a cylinder having an inner diameter of about 2 to 12 mm is formed in a cylinder having a length of about 100 mm, a length of about 20 cm to 100 cm or more, and a large number of holes or a lotus root in the axial direction.

In order to achieve the second object of the present invention, a liquid mixture separation membrane is provided on a surface of a tubular porous support.
A type 5 zeolite membrane is deposited. ZSM-5
Means for depositing the zeolite membrane on the surface of the porous support may be the above-described hydrothermal-sintering synthesis or other means such as gas-phase synthesis. In each case, a tubular porous support is used. The porous support is not particularly limited. For example, a tube or plate made of a porous material such as alumina porous, metal, organic / inorganic polymer, and ceramics can be used.

The liquid mixture separation membrane of the present invention can be used in any of a pervaporation method, a vapor permeation method, and a gas phase separation method. The ZSM-5
The liquid mixture to be separated from the type zeolite membrane is not particularly limited, for example, water, a liquid mixture of alcohols such as methanol, ethanol, and propanol,
A liquid mixture of an organic solution such as a ketone such as acetone and methyl ethyl ketone, a halogenated hydrocarbon such as carbon tetrachloride and trichloroethylene, and an alcohol such as methanol, ethanol, and propanol; the alcohol and an aromatic such as benzene and cyclohexane And a liquid mixture with a tribal group.

The ZSM-5 type zeolite membrane can be particularly effectively applied to the separation of water-alcohols such as water-methanol, water-ethanol and water-propanol. However, these are merely examples, and the liquid mixture to be separated according to the present invention is not limited to these. ZSM-5
The liquid separation operation using a zeolite membrane is usually performed under reduced pressure on the separated liquid side.

[0019]

The means for forming an aluminosilicate gel having the above molar composition ratio and performing the above-mentioned hydrothermal synthesis and calcination means that the porous support has good adhesion to the support and no defects such as pinholes. A ZSM-5 type zeolite membrane can be formed. Moreover, unlike a conventional organic liquid mixture separation membrane, a liquid mixture separation membrane in which a ZSM-5 type zeolite membrane is deposited on a porous support has excellent heat resistance, solvent resistance, and chemical resistance, and It is possible to efficiently separate a liquid with a small amount of energy consumption.

[0020]

The present invention will be described in detail with reference to the following examples. Example 1 (Synthesis Example 1) Silica sol, sodium hydroxide, water, tetrapropylammonium bromide (TPABr) were mixed in a molar composition ratio of H
₂ O / Na ₂ O 20 to 60, a Na ₂ O / SiO ₂ 1
As described above, H ₂ O / {Na ₂ O + (TPABr) ₂ O} was changed to 5
Aluminosilicate gel was prepared by mixing so as to be ~ 50.

The reaction solution and a tubular porous alumina support charged with a seed crystal on its surface (Multiporeon manufactured by Mitsui Grinding Stone Co., Ltd .: diameter 1 cm, length 20 cm, wall thickness 1 mm,
PTFE having a pore diameter of 1 μm and a porosity of 40%)
(Polytetrafluoroethylene) was charged in a pressure-resistant reaction tube. The tubular support was sealed at both ends to prevent the reaction solution from entering the tube.

Next, at a temperature of 100 to 180 ° C., 3 to 6
Hydrothermal synthesis over time. Next, the support that had been subjected to the previous reaction was put into the newly prepared reaction solution, and hydrothermal synthesis was performed 1 to 5 times in the same manner as described above. After the completion of the reaction, the support on which film formation was deposited on the surface was taken out, and the temperature was 500 ° C.
For 20 hours.

X-ray diffraction of the surface portion of the surface of the porous alumina support obtained as described above revealed that the peak pattern of the surface material of the porous alumina support obtained was a commercially available zeolite ZSM-5. The peak pattern matched well with the powder (manufactured by Union Carbide), and it was confirmed that ZSM-5 type zeolite was formed on the surface of the support.

When the film surface formed on the surface of the porous alumina support was photographed by an SEM (scanning electron microscope), as shown in FIG. 1, a dense ZSM-5 having a thickness of about 30 μm was formed on the support. A film composed of the zeolite crystal was deposited.

Example 2 (Example of Separation Membrane) Next, pervaporation performance of the ZSM-5 type zeolite membrane obtained in Example 1 was measured. First, the ZSM-5 type zeolite membrane 1 was attached to the separation cell 2 of the apparatus shown in FIG. The symbol 3 shown in FIG.
This was a tubular porous alumina support of the SM-5 type zeolite membrane 1, and the effective membrane area was 47 cm ² .

The separation cell 2 comprises a permeated liquid chamber 4 and a permeated liquid chamber 5 disposed on both sides of the permeated liquid chamber 4. The separated liquid chamber 4 is separated from the permeated liquid chamber 5 by a ZSM-5 type zeolite membrane 1. Cell 2 was placed in thermostat 6. A supply pipe 8 for the permeated liquid 7 was connected to one end of the permeated liquid chamber 4, and a discharge pipe 9 was connected to the other end. A permeated liquid storage tank 11 was attached to the supply pipe 8 via a pump 10, and a discharge liquid reservoir 13 was attached to the discharge pipe 9 via a heat exchanger 12. The separated liquid having passed through the ZSM-5 type zeolite membrane 1 was taken out in a vapor phase by a decompression means, cooled, solidified, and collected. That is, the pipe 14 connected to the permeate chamber 5 for taking out the separated liquid is connected to the pipe 14A.
And piping 14B, and cooling traps 15A, 15B, respectively.
It was connected to a vacuum pump 16 via B. Reference numeral 16 shown in FIG. 3 is a nitrogen gas discharge pipe, and 17 is a switching cock.

In the performance test, the liquid to be separated (liquid mixture) was
The liquid was supplied at a rate of 2 to ³⁰ cm ³ / min, and the internal pressure of the permeate chamber 5 was maintained at a vacuum of 0.1 Torr by the vacuum pump 16 and the cooling trap 15A or 14B. The permeability of the membrane is
Total permeation Q per unit area and unit time (kg / m
And ² h), was assessed by the α separation factor is defined by the following equation.

[0028] In the formula, F _A and F _B are the organic liquids A,
The average concentration (wt%) of water B, and P _A and P _B are the average concentrations (wt%) of organic liquid A and water B in the permeate, respectively.
It is. Table 1 summarizes the evaluation test results.

[0029]

[Table 1] 有機 Organic liquid mixed with water Separation temperature of liquid A Concentration Total permeate Q Separation coefficient 種類 type (℃) F _A (wt%) P _A (kg / m ² h) α ───────────────ア セ ト ン Acetone 30 7 84.8 1.06 74.1 Methyl ethyl ketone 30 7 93.3 0.41 185. Dioxane 30 7 20.8 0.23 3.5 Ethyl alcohol 30 7 75.9 0.25 41.8 Dimethylformamide 30 7 7. 0.59 1. か ら From the above results, ZSM-5 type zeolite The liquid mixture separation membrane in which was deposited densely on an alumina support showed high organic substance selectivity with respect to a water-organic liquid mixture.

[0030]

As described above, the ZSM-5 according to the present invention has been described.
The production method of the zeolite membrane is to form an aluminosilicate gel having the above component ratio and perform the limited hydrothermal synthesis and firing, so that the adhesion to the porous support surface is good, A ZSM-5 type zeolite membrane without defects such as holes can be formed. In addition, a liquid mixture separation membrane obtained by depositing a ZSM-5 type zeolite membrane on a tubular porous support is excellent in heat resistance, solvent resistance, and chemical resistance, unlike a conventional organic liquid mixture separation membrane. Further, it is possible to efficiently separate the mixed liquid with a small amount of energy consumption. Therefore, the separation of a liquid mixture can be advantageously applied industrially, particularly for industrial separation and recovery of organic matter dissolved in water.

[Brief description of the drawings]

FIG. 1 is a scanning electron micrograph of a zeolite membrane of an example.

FIG. 2 is an apparatus configuration diagram in which the separation performance of a zeolite membrane obtained by an example was measured.

[Explanation of symbols]

1 ZSM-5 type zeolite membrane 2 Separation cell 3 porous alumina support 4 permeated liquid chamber 5 Permeate chamber 6 Constant temperature bath 7 Permeate 10 Permeate storage tank 12 Drainage reservoir 14A Cooling trap 14B Cooling trap 15 Vacuum pump

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-105420 (JP, A) JP-A-5-279014 (JP, A) WO 94/001209 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 71/02 C01B 33/20-39/54

Claims (5)

(57) [Claims] 1. The molar composition ratio of the components of H ₂ O, Na ₂ O, SiO ₂ and tetrapropylammonium halide (TPAX) is H ₂ O / Na ₂ O = 20 to 6 respectively.
0, Na ₂ O / SiO ₂ = 1 or more, H ₂ O / ｛Na ₂ O
+ (TPAX) ₂ O｝ = 5 to 50 to form an aluminosilicate gel, and hydrothermally synthesize the aluminosilicate gel impregnated with the porous support at a temperature of 100 to 180 ° C. for 3 to 6 hours. Forming a reaction product in the form of a film covering the surface of the porous support, and then calcining the reaction product at a temperature of 400 ° C. or higher for 12 to 48 hours. 2. The method for producing a ZSM-5 type zeolite membrane according to claim 1, wherein said hydrothermal synthesis and calcination are repeated at least twice. 3. The method according to claim 1, wherein the support is a tubular porous support.
A liquid mixture separation membrane comprising depositing a ZSM-5 type zeolite membrane obtained by the method described above. 4. The porous support has an average pore diameter of 0.1 to 2
μm, 30-50% porosity alumina porous support
3. A ZSM-5 type zeolite membrane according to claim 1 or 2.
Construction method . 5. The porous support has an average pore diameter of 0.1 to 2
μm, 30-50% porosity alumina porous support
A liquid mixture separation membrane according to claim 3 .