JP5621965B2 - Alumina composite separation membrane and method for producing the same - Google Patents

Description

  The present invention relates to an alumina composite separation membrane and a method for producing the same. More specifically, the present invention relates to an alumina composite separation membrane having heat resistance, organic solvent resistance, water resistance, high resistance and low pH, and a method for producing the same. Since the alumina composite separation membrane of the present invention can control the pore size distribution region within the range of 0.3 to 40 nm (3 Å to 400 Å), it can be used as a separation membrane for various gases or liquids. Useful.

In general, ceramics have physical properties excellent in strength, heat resistance, and chemical resistance, and are widely used industrially such as substrates, filters, and catalyst carriers. In recent years, ceramics have been used as liquid and gas inorganic separation membranes by utilizing their porosity. The characteristics of inorganic membranes are that they can be used under high temperatures, pH, and organic solvents that cannot be used with organic membranes. However, it is difficult to modularize membranes, resulting in low sealing performance and high costs. There were practical problems in terms of the above.
Furthermore, in conventional inorganic membranes, high separation performance can be imparted to gas separation and separation of various low molecules by utilizing the polarity and charge of the pore surface. Therefore, it was difficult to produce a practical separation membrane by the conventional sol-gel film forming method.
Therefore, in addition to the sol-gel method, various methods such as a hydrothermal synthesis method, an anodic oxidation method, and an organic-inorganic film composite method have been studied as a method for forming an inorganic film.

  For example, JP-A-7-185275 (Patent Document 1) describes an alcohol concentration method by selectively permeating water from an aqueous alcohol solution using the hydrophilicity of A-type zeolite. However, the A-type zeolite membrane has the problems of low acid resistance and water resistance, and further, the use conditions are limited because the pore diameter is determined by the structure unique to the crystal. Furthermore, when forming such a zeolite membrane, it is necessary to put a porous carrier into a reaction vessel and to perform hydrothermal treatment, and thus there is a practical problem that a special reaction apparatus is required. .

  In JP-A-9-142964 (Patent Document 2), an alumina sol obtained by hydrolysis by adding a water-soluble organic solvent and a carboxylic acid anhydride, an acetoacetic acid ester, a dicarboxylic acid ester or the like to aluminum alkoxide is disclosed. A method for producing an alumina porous membrane obtained by applying to a porous ceramic support and firing is described. However, the particles obtained under these production conditions have a small aspect ratio and a pore size of 1 nm or more, so that the control range is narrow, so that they are not suitable for separation of gases and organic substances having smaller molecular diameters.

  Japanese Patent Application Laid-Open No. 9-316692 (Patent Document 3) describes a film having fine pores obtained by anodizing aluminum or aluminum supported on a porous inorganic material by a pulse voltage, and a method for producing the film. However, in this manufacturing method, it is necessary to support aluminum on the substrate, it is necessary to precisely control the applied voltage, and a special film forming apparatus is required. Had a problem in terms.

  In JP 2003-275550 A (Patent Document 4), an excessive gas separation membrane forming component is scattered by immersing a porous carrier in an alumina sol solution (major axis: 100 nm, minor axis: 10 nm) and pulling it up while rotating. A gas separation membrane obtained by removal and a method for producing the same are described. However, in this method, in order to obtain the target pore diameter, it is necessary to repeat the steps from immersion to drying 10 times or more, and there is a problem that enormous time is required for producing a separation membrane.

  As described above, in the prior art, there is a film forming method that satisfies the requirements necessary for practical use, that is, the range of pore diameters that can be controlled, and the film forming method is simple and can be produced at low cost. The fact is that it has not been provided yet, and there has been a demand in the art to develop an alumina separation membrane that satisfies the above requirements.

JP-A-7-185275 JP-A-9-142964 JP-A-9-316692 JP 2003-275550 A

  The present invention has a wide range of controllable pore diameters, practically sufficiently high heat resistance, organic solvent resistance, water resistance, high resistance and low pH resistance, a simple film formation method, and low cost. The present invention has been made to provide a low alumina composite separation membrane and a method for producing the same.

The alumina composite separation membrane of the present invention includes a support formed from a porous material, and a porous thin film layer formed on at least one surface of the support,
In the porous thin film layer, fibrous alumina particles having an average aspect ratio of 30 to 5000 are stacked in parallel in one direction, and the parallel and stacked fibrous alumina particles communicate with each other. It is characterized in that fine pores are formed.
In the alumina composite separation membrane of the present invention, the fibrous alumina particles preferably have an average minor axis of 1 to 10 nm and an average major axis of 100 to 10,000 nm.
In the alumina composite separation membrane of the present invention, a silane coupling agent may be contained in the porous thin film layer.
In the method for producing an alumina composite separation membrane according to the present invention, a fiber having an average aspect ratio of 30 to 5000 on at least one surface of a support formed of a porous material is used to produce the alumina composite separation membrane. An aqueous alumina hydrate sol coating layer containing dispersed alumina hydrate particles is formed, and the aqueous alumina hydrate sol coating layer is formed at a temperature of 5 to 100 ° C. for 10 minutes or more. It is dried and further heat treated at a temperature of 130 to 1000 ° C. to form a porous thin film layer containing fibrous alumina particles arranged in parallel and stacked in one direction.
In the method for producing an alumina composite separation membrane of the present invention, the alumina hydrate particles are preferably at least one kind of particles selected from boehmite or pseudoboehmite.
In the method for producing an alumina composite separation membrane of the present invention, the aqueous alumina sol is preferably prepared by hydrolyzing and peptizing aluminum alkoxide.
The method of the present invention for separating and recovering water from a mixture of water and water-soluble alcohol uses the alumina composite separation membrane of the present invention.
The method of the present invention for separating and removing the different gas from a mixed gas of water vapor and a different gas is characterized by using the alumina composite separation membrane of the present invention.

  The alumina composite separation membrane of the present invention is not only excellent in heat resistance, organic solvent resistance, water resistance, high resistance and (low) pH property, but also formed between fibrous alumina particles in the porous thin film layer. The pore diameter of the communicating pores can be controlled over a wide range of 0.3 nm to 40 nm. For this reason, for example, water is separated and recovered from a mixture of water and a water-soluble alcohol, and water vapor is different from that. The heterogeneous gas can be separated and removed with high efficiency from the mixed gas with the above gas, and in the method of the present invention, the alumina composite separation membrane can be easily produced at low cost.

The transmission electron microscope (TEM) image (magnification: x710,000 times) of the porous thin film layer containing fibrous alumina particles of the alumina composite separation membrane of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a water / IPA mixed solution separation device used in Example 1; Explanatory drawing of the separation apparatus of the water / nitrogen mixed gas used in Example 4. FIG.

  The alumina composite separation membrane of the present invention includes a support formed from a porous material and a porous thin film layer formed on at least one surface of the support. In the porous thin film layer, fibrous (also referred to as needle-shaped) alumina particles having an aspect ratio of 30 to 5000 are stacked in parallel in one direction, and these parallel and stacked fibrous alumina particles are stacked. Between these, pores communicating with each other are formed.

The support of the alumina composite separation membrane of the present invention is formed of a porous material, and the porous material used in the present invention can be selected from a wide range of porous materials as long as the object of the present invention is not impaired. . As the porous material for the support used in the present invention, for example, porous sintering made of powders of inorganic oxides such as inorganic oxides such as alumina, mullite and zirconia, metals and alloys such as stainless steel and aluminum, and hydroapatite Or an expanded porous body of a polytetrafluoroethylene resin, or a porous cellulose molded body. The porosity of the porous support is preferably 5 to 60%, more preferably 20 to 50%. Moreover, it is preferable that dpeak which shows the peak top of the pore diameter distribution curve of the porous support body used for this invention is 0.5-4.0 nm, More preferably, it is 0.6-2.0 nm.
The shape and dimension of the porous support are appropriately set in consideration of the application and use conditions of the composite separation membrane. The shape may be any of a flat membrane, a tubular body, and the like, and the thickness is preferably 0.01 to 5 mm.

The main component forming the porous thin film layer of the present invention is fibrous alumina particles, and the average aspect ratio thereof is 30 to 5000, preferably 100 to 300. The average minor axis of the fibrous alumina particles is preferably 1 to 10 nm, more preferably 2 to 5 nm, and the average major axis is preferably 100 to 10,000 nm, more preferably 500. ˜7000 nm.
When the average aspect ratio of the alumina particles is less than 30, the particle shape is columnar or rectangular plate. When alumina particles having such a shape are formed, the maximum value d peak in the pore diameter distribution in the obtained film material is It becomes larger than 1 nm and the separation performance becomes insufficient. In addition, fibrous alumina particles having an average aspect ratio exceeding 5,000 require an excessively long time to synthesize the particles, resulting in an operational disadvantage such as an increase in manufacturing cost and a decrease in manufacturing efficiency.
Further, when the average minor axis of the fibrous alumina particles is less than 1 nm, the particles are likely to aggregate randomly, the non-uniformity of the pore diameter distribution of the resulting porous thin film layer is increased, and the resulting alumina composite separation The reliability of the separation characteristics of the membrane is reduced. The synthesis of particles having an average major axis of the fibrous alumina particles exceeding 10,000 nm takes a very long time, resulting in disadvantages such as an increase in production cost and a decrease in production efficiency.

  For the measurement of the aspect ratio of the fibrous alumina particles contained in the porous thin film layer of the alumina composite separation membrane of the present invention, 300 pieces were used using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The minor axis and major axis of the particles are measured, the measured values are arithmetically averaged to determine the average minor axis and the average major axis, and the average major axis / average minor axis = aspect ratio is calculated.

The crystalline form of the fibrous alumina particles contained in the porous thin film layer of the present invention is not particularly limited, but preferably has at least one of amorphous, boehmite, and pseudo-boehmite crystal forms. Boehmite and / or pseudo boehmite crystal forms are preferred. In general, when alumina hydrate is heat-treated, its crystal form transitions to boehmite, pseudoboehmite, γ, δ, θ-alumina, etc., and finally to α-alumina. As described above, the fibrous alumina particles in the porous thin film layer in the present invention preferably have boehmite and / or pseudo-boehmite crystal form, but are amorphous and / or γ, δ, θ, α−. Those having an alumina crystal form may be included.
The crystal form of the alumina particles can be confirmed using an X-ray diffraction apparatus.
The specifications of the X-ray diffraction apparatus are as follows, for example.
Type: Mac. Sci. MXP-18
Tube: Cu, tube voltage: 40 kV
Tube current: 250 mA, goniometer: wide angle goniometer Sampling width: 0.020 °, scanning speed: 10 ° / min
Diverging slit: 0.5 °, scattering slit: 0.5 °
Receiving slit: 0.30mm

In the porous thin film layer of the alumina composite separation membrane of the present invention, the fibrous alumina particles are stacked in parallel in one direction as shown in FIG. Since each of the fibrous alumina particles that are bent is very loosely wavy, the adjacent fibrous alumina particles have sites that contact or cross contact with each other, and are narrow between these contact points. A void space forming a slit-like cross-sectional shape is formed, and these narrow void spaces, i.e., pores, are in communication with each other, permitting the transmission of substances of a specific size, and allowing the transmission of substances other than the above sizes. It is not allowed. For the distribution of the diameter of such pores, that is, the shortest distance distribution from one point on the wall surface of the pore to the opposing wall surface, the porous thin film layer specimen is brought into contact with nitrogen at the liquid nitrogen temperature, Nitrogen is adsorbed to the pores to create a nitrogen adsorption distribution curve at liquid nitrogen temperature, and the nitrogen adsorption distribution curve is analyzed by MP method or BSH method from the hysteresis depending on micropores or mesopores. In the nitrogen adsorption distribution curve, the pore diameter d peak showing the maximum distribution can be obtained.
D peak of the porous thin film layer of the present invention is preferably 0.4 nm to 40 nm, and more preferably 0.5 nm to 30 nm. When the d peak value is less than 0.4 nm, in order to solve the problem of the present invention, the size of the particles that can pass through the porous thin film layer becomes too small, and when it exceeds 40 nm, The size of the permeable particles becomes excessive.
The MP method is one of the methods for obtaining the micropore volume, micropore area, micropore distribution and the like from the adsorption isotherm (reference: RS Mikhail, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)). The BJH method is one of methods for obtaining mesopore volume, mesopore surface area, mesopore distribution, etc. from the adsorption isotherm (reference: EP Barrett, LG Joyer, PP Halenda. J. Am. Chem. Soc. 73. 373 (1951)).
In the present invention, d peak in the pore distribution in the porous thin film layer was measured by the following method.
Measuring instrument: Type Belsorb MAX, manufactured by Nippon Bell Co., Ltd. Sample amount: 100 mg
Pre-drying: 150 ° C x 1 hour, in nitrogen gas atmosphere Drying: 150 ° C x 3 hours Adsorbed gas: Nitrogen

  There is no restriction | limiting in the thickness of the porous thin film layer of the alumina composite separation membrane of this invention, Although it can set suitably in consideration of the use, desired performance, etc., it is generally 0.01-100 micrometers. Preferably, it is 0.1-50 micrometers. The desired thickness of the porous thin film layer may be achieved by a single coating or may be achieved by two or more times of repeated coating. In general, the thickness of the porous thin film layer formed by one application is preferably in the range of 0.01 to 100 μm in order to form a uniform thin film layer. The thickness of the porous thin film layer can be measured by observing the cross section of the alumina composite separation membrane with an SEM. The cross section for SEM observation can be created using an apparatus such as ion milling.

  Hydroxyl groups are present on the surface of the fibrous alumina particles used in the present invention, and these hydroxyl groups can be easily modified. For this modification, a silane coupling agent, a silylating agent, a polyhydric alcohol, an aluminum chelate compound, a titanium chelate compound, an aromatic sulfonic acid, phosphoric acid, a long chain carboxylic acid, or the like can be used as a modifying agent. The amount of modification by the modifying agent is preferably 0.01 to 2 mol% with respect to 1 mol of aluminum contained in the fibrous alumina particles.

As the silane coupling agent for modifying the surface hydroxyl group of fibrous alumina particles, the types of silane coupling are vinyl type such as vinyltrichlorosilane and vinyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltri Epoxy systems such as methoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-aminopropyltri Amine-based silane treating agents such as methoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldi Ethoxysilane, 3 And isocyanate propyl triethoxysilane and the like. The modification amount by the silane coupling agent is 0.01 to 2 mol, preferably 0.05 to 1 mol, per 1 mol of aluminum contained in the alumina particles. If it is less than 0.01 mol, the expected modification effect may be insufficient, and if it is more than 2 mol, the SiO2 layer becomes thick and precise control of the pores becomes difficult, Furthermore, it is disadvantageous in terms of price, which is not preferable.
As a method for adding the silane coupling agent, the silane coupling agent may be added to the aqueous hydrated alumina sol solution and mixed uniformly. Further, when a uniform mixed solution with the alumina hydrate sol aqueous solution cannot be formed, it can be treated by applying a silane coupling agent solution diluted with a solvent on the separation membrane after forming the separation membrane.
In the case of an alumina separation membrane, since the particle surface has a large amount of hydroxyl groups, the membrane surface and pores are hydrophilic. Therefore, hydrophilic substances such as water are easy to pass through, and hydrophobic substances such as benzene and butanol are difficult to pass through the membrane. By changing the polarity of the surface by silane coupling treatment, the substance that can pass through the membrane can be controlled.

The method for producing an alumina composite separation membrane according to the present invention comprises an average aspect ratio of 30 to 5000 on at least one surface of a support formed from a porous material in order to produce the alumina composite separation membrane according to the present invention. An aqueous alumina hydrate sol coating layer in which fibrous alumina hydrate particles having a dispersion are contained is formed, and the aqueous alumina sol coating layer is formed at a temperature of 5 to 100 ° C. for 10 minutes or more. It is dried and further heat treated at a temperature of 130 to 1000 ° C. to form a porous thin film layer containing fibrous alumina particles arranged in parallel and stacked in one direction.
Although there is no special restriction | limiting in the preparation method of the aqueous | water-based alumina sol used for this invention method, For example, it is preferable to use the following method.
That is, the hydrolyzable aluminum compound is hydrolyzed, and the resulting aluminum hydroxide-containing aqueous mixture is peptized under acidic conditions. Aqueous alumina sol containing amorphous, boehmite crystal or pseudoboehmite crystal hydrate particles can be prepared by appropriately selecting the type of hydrolyzable aluminum compound, hydrolysis conditions and peptization conditions. . At this time, the crystal form of the alumina hydrate particles is preferably boehmite, pseudoboehmite, or a mixture thereof.

  The hydrolyzable aluminum compound includes various inorganic aluminum compounds and aluminum compounds having an organic group. Examples of the inorganic aluminum compound include salts of inorganic acids such as aluminum chloride, aluminum sulfate, and aluminum nitrate, aluminates such as sodium aluminate, and aluminum hydroxide.

  Examples of the hydrolyzable aluminum compound having an organic group include aluminum carbonate carbonates, carboxylates such as aluminum acetate, aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum alkoxides such as aluminum sec-butoxide, Examples include cyclic aluminum oligomers, aluminum chelates such as diisopropoxy (ethylacetoacetato) aluminum and tris (ethylacetoacetato) aluminum, and organoaluminum compounds such as alkylaluminum.

  Among the above hydrolyzable aluminum compounds, it is preferable to use aluminum alkoxide because it has moderate hydrolyzability and easy removal of by-products, and has an alkoxyl group having 2 to 5 carbon atoms. Is particularly preferred. The amount of water used for the hydrolysis is adjusted so that the concentration of fibrous alumina, preferably boehmite or pseudoboehmite hydrate particles in the aqueous alumina hydrate sol is 0.1 to 20% by mass. It is preferable that the content is adjusted to 0.5 to 10% by mass.

  When the concentration of fibrous alumina hydrate, preferably boehmite or pseudo-boehmite hydrate particles in the aqueous alumina hydrate sol is 0.1% by mass or less, it is applied to create an appropriate film thickness. -It is not preferable because it is necessary to repeat the drying operation and the operation becomes complicated. When the content is 20% by mass or more, the viscosity of the dispersion becomes high, and it may be difficult to form a uniform film. . Alcohols, ketones, ethers, water-soluble polymers, and the like can be added to the aqueous alumina hydrate sol as long as the target alumina porous material does not adversely affect the properties of the membrane layer.

  In hydrolysis of the hydrolyzable aluminum compound, after adding a predetermined amount of hydrolyzable aluminum compound to a predetermined amount of water, it is heated to a temperature in the range of 80 to 170 ° C. for 0.5 to 10 hours, preferably Hydrothermal treatment is performed by heating at a temperature in the range of 100 to 150 ° C. for 1 to 5 hours. When the water treatment temperature is less than 80 ° C., it takes a long time for hydrolysis, and even if it is carried out at a temperature exceeding 170 ° C., the increase in hydrolysis rate is slight, and this high temperature Since a high pressure vessel is required for processing, it is economically disadvantageous. It is not preferable. When the hydrolysis treatment time is less than 0.5 hours, it is difficult to control the temperature, and even if it is heated for more than 10 hours, the process time is increased and there is no advantage.

  The slurry in water of alumina obtained by the above hydrolysis is heated in the presence of an acid to peptize (alumina hydrate particle aggregate is dispersed in colloidal fine particles in a solvent). The acid used for peptization is preferably a monovalent acid such as hydrochloric acid, nitric acid, formic acid or acetic acid. Usually, it is more preferable to use acetic acid. The amount of acid added is preferably 0.1 to 2 mol times, more preferably 0.3 to 1.5 mol times the amount of hydrolyzable alumina hydrate particles. When the coexistence amount of the acid in the flocculated alumina colloid liquid is less than 0.1 mole times the amount of the alumina hydrate particles, flocculation may not sufficiently proceed. Alumina hydrate in the aqueous alumina sol after peptization has at least one of an average short diameter of 1 to 10 nm, an average long diameter of 100 to 10000 nm, and a fiber (or needle shape) having an average aspect ratio of 30 to 5000. May not have. When the coexistence amount of the acid exceeds 2 mole times, the temporal stability of the resulting aqueous gel of alumina hydrate is lowered, and the practicality may be lowered.

  In the method of the present invention, the pH value of the fibrous alumina hydrate sol for forming a porous thin film layer used is preferably 2.5 to 4, more preferably 2.7 to 3.7. This improves the temporal stability of the alumina hydrate sol. However, it is possible to form a porous thin film layer containing fine particles of alumina hydrate even if the pH of the alumina hydrate sol is neutral or alkaline. In this case, as the pH value adjusting agent of the alumina hydrate aqueous sol, inorganic compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate and ammonium carbonate, and ethylamine, tetramethylammonium hydroxide, urea, etc. These organic amine compounds can be used. Of these basic pH value adjusting agents, sodium or potassium hydroxide carbonate is not practically preferable because the metal component contained therein remains after firing. Further, in the process of forming the alumina porous thin film layer, when the acidic pH value adjusting agent is neutralized by generating ammonia, organic amine, etc., neutralization of the obtained alumina hydrate gel after the peptization May be omitted.

  When the viscosity of the obtained aqueous alumina hydrate sol is high, bubbles are likely to remain in the sol, and it may be necessary to perform a deaeration (defoaming) treatment on the bubbles. As a degassing method, a decompression process, a centrifugal process, or the like can be used. The deaerated aqueous alumina hydrate sol is applied to the desired surface of the porous support, the dispersion medium is removed by drying, and heat treatment is performed to form a porous thin film layer.

In addition, the application method and conditions of the alumina hydrate gel can be set in consideration of the viscosity of the obtained alumina hydrate gel, the desired shape and thickness of the porous thin film layer, and the like. The method for applying the alumina hydrate sol to the desired surface of the porous support can be selected, for example, from the following methods.
1. The alumina hydrate sol was diluted with water, a method of adjusting the diluted aqueous solution, and spray coating, the coating amount of hydrated alumina, for example, ^{2g / m 2 ~30g / m 2} .
2. After immersing the porous support in an aqueous solution of alumina hydrate sol and letting it stay for a desired time, for example, 10 seconds to 10 minutes, it is pulled up at a predetermined speed, for example, 0.05 m / min to 1 m / min, desired value hydrated alumina attachment mass to the porous support, for example, adjusting (gravity flow, or stop) to 2g / m ² ~30g / m ² how to.
3. Other methods using known coating methods (blade coating, roll coating, brush coating, slit coating, transfer method, etc.).
As described above, a coating layer having a desired coating amount may be formed by a single coating operation or may be formed by two or more overcoating operations.

  As described above, the aqueous alumina hydrate sol coating layer applied to the desired surface of the porous support is applied at a temperature of 5 to 100 ° C., preferably 10 to 60 ° C. for 10 minutes or more, preferably 10 Dry for min-hour to remove the dispersion medium of the aqueous alumina hydrate sol. At this time, it is preferable to gradually raise the temperature. By such a low-temperature and long-time drying treatment, the fibrous particles of alumina hydrate can be arranged and stacked in one direction. It is preferable to use a constant temperature drying apparatus for such drying.

The dried fibrous particle-containing coating layer of alumina hydrate is further heat-treated at a temperature of 130 to 1000 ° C, preferably 150 to 600 ° C. The heat treatment time is preferably 30 minutes to 5 hours, more preferably 1 hour to 3 hours. For this heat treatment, a constant temperature heat treatment apparatus such as a firing furnace (electric furnace) can be used. By this heat treatment, the fibrous particles of alumina hydrate are stacked in parallel in one direction, and then dehydrated to become fibrous alumina particles to form a porous thin film layer.
By appropriately setting the temperature of this heat treatment, the crystal form of the obtained fibrous alumina particles can be controlled. That is, it changes to γ-alumina at a heat treatment temperature of 300 to 500 ° C., changes to δ, θ-alumina around 800 ° C., and changes to α-alumina at 1100 ° C. or higher.

The alumina composite separation membrane of the present invention has a desired shape and size by having a composite structure from a porous support and a porous thin film layer, and can have practically sufficient durability. And it can manufacture easily by the method of this invention.
Furthermore, in the alumina composite separation membrane of the present invention, the fibrous alumina particles in the porous thin film layer have a predetermined average minor axis, average major axis and aspect ratio, and are stacked in parallel in one direction. Thus, uniform separation performance can be expressed.

  The alumina composite separation membrane of the present invention and the production method thereof will be further described in the following examples.

Example 1
As the porous support, a porous tube containing α-alumina as a main component and having the following dimensions and shape was used.
Outer diameter: 2mm
Inner diameter: 1.6mm
Length: 50mm
Average pore diameter: 135nm
Porosity: 40%
An aqueous alumina hydrate sol in which the following fibrous alumina hydrate particles were dispersed was prepared.
Average aspect ratio of fibrous alumina hydrate particles: 400
Average minor axis: 5 nm
Average major axis: 2000nm
Concentration of alumina hydrate in sol: 5% by mass
Both ends of the porous α-alumina tube are plugged and closed, and this is immersed in 15 g of the aqueous alumina hydrate sol for 5 minutes, and then the porous tube is slowly pulled up over 1 minute, A coating layer made of an alumina hydrate sol was formed on the outer surface, and this was dried in a constant temperature drying apparatus at 30 ° C. for 2 hours, and then heat-treated in a constant temperature drying apparatus at 150 ° C. for 2 hours.
The porous thin film layer of the obtained tubular alumina composite separation membrane had a thickness of 20 μm. When this porous thin film layer was peeled off and the pore size distribution was measured by a nitrogen adsorption method (MP method), the d peak of the pore size distribution with a pore size of 100 nm or less was 1 nm.

Evaluation of water / IPA separation characteristics of alumina composite separation membrane by permeation method (IPA: isopropyl alcohol)
As shown in FIG. 2, the lower end 2 of the tubular alumina composite separation membrane 1 is sealed with an epoxy resin adhesive (trademark: Toll Seal, manufactured by Nicola Corporation), and the upper end 3 is sealed with a SUS cell. The lower end of 4 was airtightly bonded and fixed using the epoxy resin adhesive. The tubular alumina composite separation membrane fixed to the SUS cell is immersed in a 10:90 volume ratio mixed solution 5 of water and IPA at 40 ° C., and the inside of the tubular alumina composite separation membrane is stirred with the stirrer 6. Depressurized to vacuum. At this time, the vaporized component that has permeated through the separation membrane in vacuum from the water / IPA mixed solution is collected in the collector 7 via the SUS cell 4, and is rapidly cooled with liquid nitrogen 8 to be liquefied. The liquefied component 9 was collected at the bottom of the collector 7. This liquefied component was subjected to gas chromatography, and the composition of the collected liquid was quantitatively analyzed. As a result, the collected liquid 9 was water having a purity of 99.95% by volume or more. The separation membrane permeation flux of vaporized water in this separation was 0.4 kg / m ² · h. The liquid collected in the collector 9 can be discharged through the discharge pipe 10. In the separation of water from the water / IPA mixed solution, the excellent separation performance of the separation membrane of Example 1 was confirmed.
The “permeation flux” is represented by the mass (kg) of the substance permeated through the separation membrane per unit time (h) and unit area (m ² ).

Example 2
An alumina composite separation membrane was prepared in the same manner as in Example 1. However, fibrous alumina hydrate particles having an average minor axis: 5 nm, an average major axis: 4000 nm, and an average aspect ratio: 800 were used. As a result of measuring the pore distribution of the porous thin film layer of the obtained alumina composite separation membrane, the d peak of pores having a pore diameter of 100 nm or less was 1 nm.
The obtained alumina composite separation membrane was subjected to the same water / IPA liquid mixture separation test as in Example 1. The collected liquid component was water having a purity of 99.90% by volume. The permeation flux of water at this time was 0.6 kg / m ² · h.

Example 3
An alumina composite separation membrane was prepared in the same manner as in Example 1. However, as the fibrous alumina hydrate particles, those having an average minor axis: 3 nm, an average major axis: 6000 nm, and an average aspect ratio: 2000 were used. When the pore distribution of the obtained porous thin film layer was measured, the d peak of pores having a pore diameter of 100 nm or less was 1.1 nm.
The alumina composite separation membrane was subjected to a water / IPA mixed liquid separation test in the same manner as in Example 1. The liquid component collected as a result was water having a purity of 99.90% by volume, and the water permeation flux was 0.6 kg / m ² · h.

Example 4 (Example of separation of mixed gas)
The alumina composite separation membrane prepared in Example 1 was subjected to a water / nitrogen mixed gas separation test.
As shown in FIG. 3, the lower end 2 of the tubular alumina composite separation membrane 1 was sealed, and the upper end 3 was airtightly connected to the lower end of the SUS cell 4. The upper end of the SUS cell 4 was connected to the mass spectrometer 11. The tubular alumina composite separation membrane 1 is held in air (water: 1.23 mol%, nitrogen: 78.2 mol%), the inside of the tubular separation membrane 1 is evacuated to a vacuum, and the gas that has permeated the tubular separation membrane The SUS cell diameter was sent together with helium (He) gas to the mass spectrometer 11 (Hidden HAL 301 / F PIC Quadrupol Mass Spectrometer) to analyze the permeated gas. As a result, the water / nitrogen permeation rate ratio was 5785, and the water permeation rate was 0.0000000461 mol / m ² · s · Pa. The water / nitrogen permeation rate ratio is a ratio of water permeation rate to nitrogen permeation rate. In this example, the permeation rate of water that permeates through the alumina composite separation membrane is 5785 times the permeation rate of nitrogen, and this separation membrane is high in separation recovery, effect for water, or high for nitrogen. It was confirmed to have a removal effect.

Example 5
The same porous α-alumina tube as in Example 1 was used as a support.
As a coating solution containing an aqueous alumina hydrate sol, a mixed solution of 15 g of the same aqueous alumina hydrate sol as described in Example 1 and 0.8 g of 3-glycidoxypropyltrimethoxysilane was used. .
Both ends of the α-alumina tube are sealed, immersed in the coating solution at room temperature for 5 minutes, slowly pulled up over 1 minute, dried in a constant temperature dryer at a temperature of 30 ° C. for 2 hours, and 150 ° C. 2 Time heat treatment was applied.
When the pore diameter distribution of the obtained tubular alumina composite separation membrane was measured, d peak was 0.5 nm in pores having a pore diameter of 100 nm or less.
The obtained tubular alumina composite separation membrane was subjected to a test for separating water from a water / nitrogen mixed gas using a mass spectrometer having the structure shown in FIG. As a result of analysis, the water / nitrogen permeation rate ratio was 2415, and the water permeation rate was 0.000000000025 mol / m ² · s · Pa.

Comparative Example 1
An alumina composite separation membrane was prepared in the same manner as in Example 1, and a water / IPA mixed solution separation test was conducted.
However, a columnar alumina hydrate particle sol having an average minor axis: 10 nm, an average major axis: 50 nm, and an average aspect ratio: 5 was used as the fibrous alumina hydrate sol. In the pore distribution measurement result of the porous thin film layer of the obtained alumina composite separation membrane, the d peak of pores having a pore diameter of 100 nm or less was 4.2 nm.
Further, the water content of the liquid component collected in the water / IPA mixed solution separation test was 12% by volume, and the permeation flux of the permeated liquid component was 6 kg / m ² · h.

Comparative Example 2
An alumina composite separation membrane was prepared in the same manner as in Example 1, and a water / IPA mixed solution separation test was conducted.
However, as the fibrous alumina hydrate sol, a columnar alumina hydrate particle sol having an average minor axis: 5 nm, an average major axis: 100 nm, and an average aspect ratio: 20 was used. In the result of measuring the pore distribution of the porous thin film layer of the obtained alumina composite separation membrane, the d peak of pores having a pore diameter of 100 nm or less was 4.7 nm.
Further, the water content of the liquid component collected in the water / IPA mixed solution separation test was 15% by volume, and the permeation flux of the permeate liquid component was 5.5 kg / m ² · h.

Comparative Example 3 (Separation of water / nitrogen mixed gas)
The alumina composite separation membrane prepared using the columnar aluminum hydrate sol in Comparative Example 1 was subjected to the same water / nitrogen mixed gas separation test as in Example 4. As a result, the water / nitrogen permeation rate ratio was 1, and the water permeation rate was 0.00000541 mol / m ² · s · Pa. No water / nitrogen separation effect was observed.

  The alumina composite separation membrane of the present invention is not only useful for separation of a mixed liquid and a mixed gas, but also supports a functional substance (for example, a catalyst or an enzyme), an electrolytic partition wall, a catalyst membrane, and a catalytic performance of alumina. Can be utilized in various industries as a membrane material that exhibits both the effects of concentration and separation of the mixed liquid and catalytic reaction at the same time.

DESCRIPTION OF SYMBOLS 1 Tubular alumina composite separation membrane 2 Lower end 3 Upper end 4 SUS cell 5 Water / IPA mixed solution 6 Stirrer 7 Collector 8 Liquid nitrogen 9 Liquefaction component 10 Discharge pipe 11 Mass spectrometer

Claims (8)

A support formed from a porous material, and a porous thin film layer formed on at least one surface of the support;
In the porous thin film layer, fibrous alumina particles having an average aspect ratio of 30 to 5000 are stacked in parallel in one direction, and the parallel and stacked fibrous alumina particles communicate with each other. An alumina composite separation membrane characterized in that pores are formed ,
The average minor axis of the fibrous alumina particles is 1 to 10 nm, and the average major axis is 100 to 10,000 nm,
An alumina composite separation membrane for separating and recovering water from a mixture of water and water-soluble alcohol . A support formed from a porous material, and a porous thin film layer formed on at least one surface of the support;
In the porous thin film layer, fibrous alumina particles having an average aspect ratio of 30 to 5000 are stacked in parallel in one direction, and the parallel and stacked fibrous alumina particles communicate with each other. An alumina composite separation membrane characterized in that pores are formed,
The average minor axis of the fibrous alumina particles is 1 to 10 nm, and the average major axis is 100 to 10,000 nm,
An alumina composite separation membrane for separating and removing the different gas from a mixed gas of water vapor and a different gas.   The alumina composite separation membrane according to claim 1 or 2, wherein a silane coupling agent is contained in the porous thin film layer. In order to produce the alumina composite separation membrane according to any one of claims 1 to 3, a fibrous material having an average aspect ratio of 30 to 5000 on at least one surface of a support formed of a porous material. A coating layer of an aqueous alumina hydrate sol containing dispersed alumina hydrate particles is formed, and the aqueous alumina hydrate sol coating layer is dried at a temperature of 5 to 100 ° C. for 10 minutes or more. And a heat treatment at a temperature of 130 to 1000 ° C. to form a porous thin film layer containing fibrous alumina particles arranged in parallel and stacked in one direction.   The method for producing an alumina composite separation membrane according to claim 4, wherein the alumina hydrate particles are at least one kind of particles selected from boehmite or pseudoboehmite.   The method for producing an alumina composite separation membrane according to claim 4 or 5, wherein the aqueous alumina sol is prepared by hydrolyzing and peptizing aluminum alkoxide. A method for separating and recovering water from a mixture of water and a water-soluble alcohol using the alumina composite separation membrane according to claim 1 . A method for separating and removing the different gas from a mixed gas of water vapor and a different gas using the alumina composite separation membrane according to claim 1 .