JP6728583B2 - How to remove trace alcohol - Google Patents

Description

The present invention relates to a method for removing a trace amount of alcohol contained in water, and specifically to a method for removing a trace amount of alcohol from a trace alcohol-containing aqueous solution obtained by a separation means such as membrane separation.

A technique for separating alcohol and water from an aqueous solution containing alcohol is used in various fields.
For example, in the field of food, Patent Document 1 discloses a method of extracting alcohol and water from an alcoholic beverage using a reverse osmosis membrane, and then separating the water and alcohol to return the alcohol to the alcoholic beverage. Further, for example, in Patent Document 2, freeze-concentration of sake separates ice containing water as a main component and a liquid containing concentrated ethanol.

Further, industrially, for example, in Patent Document 3, as a method for extracting only alcohol in a high concentration from a mixture of alcohol and water, first, most water is removed by distillation, and then pressure swing adsorption using an adsorbent is performed. A method for removing residual moisture by an apparatus is disclosed.
Further, in Patent Document 4, as a method of dehydrating a mixture of ethanol and water, a method of interposing a membrane separation means between the distillation column and PSA is proposed. Further, a method has been proposed in which the purge gas discharged from the PSA is supplied to the membrane separation means to obtain high-concentration ethanol.

In this way, by separating alcohol from water, a product or the like having an adjusted alcohol concentration is manufactured. On the other hand, in addition to the product, water containing a small amount of alcohol as a by-product is discharged. Since water containing a trace amount of alcohol contains a certain amount or more of alcohol, problems such as waste liquid treatment have occurred.

U.S. Pat. No. 4,999,209 Japanese Patent No. 4326526 JP 2000-334257A JP, 2008-86988, A

In the present invention, by separating alcohol and water, a product or the like having an adjusted alcohol concentration is produced, while a trace amount of alcohol is removed energetically efficiently from water containing a trace amount of alcohol discharged. , To solve the problem of waste liquid treatment.

As a result of diligent studies by the present inventors, it was found that the above problems can be solved by using a method of removing a trace amount of alcohol contained in water by an alcohol-selective separation membrane using a vapor permeation method. Arrived
That is, the present invention has the following gist.
[1] An aqueous solution containing alcohol is separated into an alcohol content and a water content, and then a trace amount of the alcohol contained in the water content is removed by a vapor permeation method using an alcohol-selective separation membrane. How to remove trace alcohol.
[2] The method for removing a trace amount of alcohol according to [1], wherein the trace amount of alcohol is 10% by mass or less.
[3] The method for removing a trace amount of alcohol according to [1] or [2], wherein 30% by mass or more of the trace amount of alcohol is removed by an alcohol-selective separation membrane.
[4] The method for removing a trace amount of alcohol according to any one of [1] to [3], wherein the content of alcohol after removal by the alcohol-selective separation membrane is less than 1% by mass.
[5] The method for removing a trace amount of alcohol according to any one of [1] to [4], wherein an aqueous solution containing alcohol is separated into an alcohol content and a water content by an adsorbent or a membrane separation.
[6] The method for removing a trace amount of alcohol according to any one of [1] to [5], wherein the alcohol is ethanol.

According to the present invention, a minute amount of alcohol can be energetically efficiently removed from water containing a minute amount of alcohol discharged while a product or the like having an adjusted alcohol concentration is manufactured. As a result, the alcohol concentration can be reduced to the amount of alcohol within a range that does not pose a problem during waste liquid treatment.

Schematic diagram of the equipment used to remove alcohol by vapor permeation

The description of the constituent elements described below is an example (representative example) of the embodiment of the present invention, and the contents are not specified.
The method for removing a trace amount of alcohol of the present invention is to separate an aqueous solution containing alcohol into alcohol content and water, and then remove a trace amount of alcohol contained in the water by a vapor permeation method using an alcohol-selective separation membrane. It is characterized by doing.

Examples of the alcohol in the present invention include alcohols having 4 or less carbon atoms such as methanol, ethanol, isopropanol, propanol and butanol, but ethanol is particularly preferably applied.
First, the step (first separation step) of separating an aqueous solution containing alcohol into alcohol content and water will be described.

Examples of the method for separating the aqueous solution containing alcohol into alcohol and water include distillation, separation by an adsorbent, and membrane separation. From the viewpoint of energy efficiency, separation by an adsorbent or membrane separation is preferable.
Examples of the separation using an adsorbent include pressure swing adsorption (PSA), temperature swing adsorption (TSA), and pressure temperature swing adsorption (PTSA) in which both are combined.

The PSA has a function of adsorbing water or the like on the adsorbent by increasing the pressure and desorbing water or the like from the adsorbent by decreasing the pressure. On the other hand, TSA has a function of adsorbing water or the like to an adsorbent and supplying heated gas (such as nitrogen) to raise the temperature to desorb water or the like from the adsorbent.
PSA, TSA, and PTSA are widely used because of their relatively simple device configurations. As the adsorbent, synthetic zeolite "Molecular Sieve" (trade name) is preferably used because of its high dehydration ability. It

For membrane separation, dialysis membrane, microfiltration membrane (MF membrane), ultrafiltration membrane (UF membrane), nanofiltration membrane (NF membrane), reverse osmosis membrane (RO membrane), zeolite membrane, polymer such as polyimide membrane Mixed matrix membrane (hereinafter MM
M) and the like. From the viewpoint of separation performance, it is preferable to use a nanofiltration membrane, a reverse osmosis membrane, a zeolite membrane, a polymer membrane, or MMM, and from the viewpoint of durability, it is preferable to use a zeolite membrane.

In membrane separation, when separating an aqueous solution containing alcohol into alcohol and water, the substance that permeates the membrane may be alcohol or water. In either case, a small amount of alcohol remains on the water side in most cases.
When a zeolite membrane is used in membrane separation, the zeolite membrane can be either a membrane made of zeolite alone or a zeolite powder dispersed in a binder such as a polymer to form a membrane on various supports. It may be a zeolite membrane composite in which zeolite is fixed in a film form.

Among them, a zeolite membrane composite in which zeolite is adhered in a membrane form on a porous support is particularly preferable. That is, since the zeolite membrane composite has a support, the mechanical strength is increased, the handling becomes easy, various device designs are possible, and in particular, when the inorganic porous support is used, the zeolite membrane composite is Since the whole body is composed of an inorganic substance, it has excellent heat resistance, chemical resistance, and durability, and can be stably used for a long period of time for concentrating liquid foods. The porous support that constitutes the zeolite membrane composite has a chemical stability such that zeolite can be crystallized into a film on its surface, and is a support made of an inorganic porous material (inorganic porous support). Preferred are, for example, ceramics sintered bodies (ceramics support) such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride and silicon carbide, and sintered metals such as iron, bronze and stainless steel. Examples thereof include glass and carbon molded bodies, and of these, a ceramic support is preferable.

The shape of the porous support is not particularly limited as long as it can efficiently separate the liquid to be treated, and for example, a flat plate shape, a tubular shape (for example, a cylindrical tubular shape, a rectangular tubular shape), a honeycomb shape (for example, a cylindrical shape, A honeycomb shape having a large number of cylindrical or prismatic holes), a monolith and the like can be mentioned. Of these, a tubular support is particularly preferable, and a cylindrical tubular support is particularly preferable.
After the aqueous solution containing alcohol is separated into the alcohol content and the water by using the method as described above, the trace amount of alcohol contained in the water is usually 10% by mass or less, but preferably 5% by mass or less. 3 mass% or less is more preferable, and 2 mass% or less is further preferable.
The trace amount of alcohol contained in water is usually 0.3% by mass or more, preferably 0.5% by mass or more, more preferably 0.7% by mass or more, still more preferably 1% by mass or more. Water containing such a trace amount of alcohol is removed by a vapor permeation method using an alcohol-selective separation membrane.

Here, examples of the alcohol-selective separation membrane include a polyolefin membrane, a perfluorinated olefin membrane, a polyamide membrane, a polyuric acid membrane, a silicon rubber membrane, and a zeolite membrane, but the zeolite membrane has a separation performance and durability. preferable.
In the present invention, the zeolite membrane may be a zeolite membrane alone, or a zeolite powder dispersed in a binder such as a polymer to form a membrane, or a zeolite membrane on various supports. It may be a fixed zeolite membrane composite. Among them, a zeolite membrane composite in which zeolite is adhered in a film form on a porous support is particularly preferable, and among them, it is preferable that the membrane substantially consists of zeolite.

Incidentally, in the present invention, the membrane consisting essentially of zeolite is usually a membrane in which 90 mass% or more of the membrane is zeolite, preferably 95 mass% or more, more preferably 98 mass% or more, particularly It is preferably 99% by mass or more.
That is, the zeolite membrane composite has increased mechanical strength by having a support, easy handling, various device design is possible, especially when using an inorganic porous support,
Since the zeolite membrane composite is composed entirely of inorganic substances, it has excellent heat resistance, chemical resistance, and durability, and can be used stably for a long period of time.

The porous support that constitutes the zeolite membrane composite has a chemical stability such that zeolite can be crystallized into a film on its surface, and is a support made of an inorganic porous material (inorganic porous support). Preferred are, for example, ceramics sintered bodies (ceramics support) such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride and silicon carbide, and sintered metals such as iron, bronze and stainless steel. Examples thereof include glass and carbon molded bodies, and of these, a ceramic support is preferable.

As the ceramic support, as described above, specifically, a ceramic sintered body containing silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, etc. However, a ceramic support containing at least one of alumina, silica, and mullite is preferable.

The shape of the porous support is not particularly limited as long as alcohol can be efficiently separated from the liquid to be treated, and examples thereof include flat plate, tubular (eg, cylindrical tubular, rectangular tubular), and honeycomb (eg cylindrical). Shape, a honeycomb shape having a large number of cylindrical or prismatic holes), and a monolith. Of these, a tubular support is particularly preferable, and a cylindrical tubular support is particularly preferable.
The average thickness (wall thickness) of the porous support is usually 0.1 mm or more, preferably 0.3 mm or more, more preferably 0.5 mm or more, and usually 7 mm or less, preferably 5 mm or less, more preferably 3 mm. It is as follows.

The porosity of the porous support is usually 20% or more, preferably 25% or more, more preferably 30% or more, and usually 70% or less, preferably 60% or less, more preferably 50% or less.
When the porous support is a cylindrical tubular support, the outer diameter of the cylindrical tube is usually 3 mm or more, preferably 5.5 mm or more, more preferably 9.5 mm or more, particularly preferably 11 mm or more, usually 51 mm or less, It is preferably 31 mm or less, more preferably 21 mm or less, still more preferably 17 mm or less, and particularly preferably 15 mm or less.

A zeolite membrane composite is obtained by forming a zeolite membrane on such a porous support.
As a component constituting the zeolite membrane, besides zeolite, an inorganic binder such as silica and alumina, an organic compound such as a polymer, or a material containing a Si atom for modifying the zeolite surface as described in detail below (silylating agent) or the same A reaction product and the like may be included if necessary. Moreover, the zeolite membrane in the present invention may partially contain an amorphous component or the like. The zeolite is preferably aluminophosphate, silico-alcomonophosphate, aluminosilicate or silicate, and aluminosilicate or silicate is particularly preferable.

The thickness of the zeolite membrane is not particularly limited, but is usually 0.1 μm or more, preferably 0.6 μm or more, more preferably 1.0 μm or more and usually 100 μm or less, preferably 60 μm or less, more preferably 20 μm or less. Is. If the film thickness is too large, the permeation amount tends to decrease, and if it is too small, the selectivity or the film strength tends to decrease.
The particle size of zeolite is not particularly limited, but if it is too small, the grain boundaries become large and the permeation selectivity tends to be lowered. Therefore, it is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, and the upper limit is the film thickness or less. Furthermore, it is particularly preferable that the particle size of zeolite is the same as the thickness of the membrane.

The method of measuring the particle size is not particularly limited, but as an example, it can be measured by observing the surface of the zeolite membrane with SEM, observing the cross section of the zeolite membrane with SEM, or observing the zeolite membrane with TEM.
The SiO ₂ /Al ₂ O ₃ molar ratio of the zeolite membrane itself is usually 50 or higher, preferably 100 or higher, more preferably 200 or higher, still more preferably 300 or higher, and usually 10,000 or lower. When the SiO ₂ /Al ₂ O ₃ molar ratio of the zeolite membrane is within this range, the zeolite membrane becomes a membrane that is excellent in hydrophobicity, acid resistance, and water resistance, and trace amount of alcohol can be obtained by selectively permeating ethanol. It is preferably used for removal.

_SiO 2 / _Al 2 _{O 3} molar ratio of the zeolite membrane itself, a scanning electron microscope - is a value obtained by energy dispersive X-ray spectroscopy (SEM-EDX). In the SEM-EDX, by measuring the X-ray acceleration voltage at about 10 kV, it is possible to obtain information only on a film of several microns. Since the zeolite membrane is uniformly formed, the SiO ₂ /Al ₂ O ₃ molar ratio of the membrane itself can be determined by this measurement.

The main zeolite constituting the zeolite membrane preferably contains a zeolite having a pore structure of oxygen 12-membered ring or less, oxygen 6-membered ring or more, and a zeolite having a pore structure of oxygen 12-membered ring or less, 8-membered ring or more. Are more preferable, and those containing a zeolite having a pore structure of oxygen 12-membered ring or less and oxygen 10-membered ring or more are particularly preferable.
The value of n of the zeolite having an oxygen n-membered ring here is the highest in the number of oxygen in the pores composed of oxygen forming the zeolite skeleton and T element (element other than oxygen forming the skeleton). Show things. For example, when there are pores of oxygen 12-membered ring and 8-membered ring such as MOR type zeolite, it is regarded as oxygen 12-membered ring zeolite.

As the zeolite having a pore structure of oxygen 12-membered ring or less and oxygen 6-membered ring or more, for example, AEI, AEL, AFI, AFG, ANA, ATO, BEA, BRE, CAS, CDO, CHA, CON, DDR, DOH , EAB, EPI, ERI, ESV, EUO, FAR,
FAU, FER, FRA, HEU, GIS, GIU, GME, GOO, ITE, KFI, LEV, LIO, LOS, LTA, LTL, LTN, MAR, MEP, MER, MEL, MFI, MON, MOR, MSO, MTF, Examples include MTN, MTW, MWW, NON, NES, OFF, PAU, PHI, RHO, RTE, RTH, RUT, SGT, SOD, STI, STT, TOL, TON, TSC, UFI, VNI, WEI, YUG and the like.

Among these, examples of the zeolite having a pore structure of oxygen 12-membered ring or less and oxygen 8-membered ring or more include, for example, AEI, AEL, AFI, ANA, ATO, BEA, BRE, CAS, CDO, CHA, CON, and DDR. , EAB, EPI, ERI, ESV, EUO, FER, FAU, HEU, GIS, GME, GOO, ITE, KFI, LEV, LTA, LTL, MER, MEL, MOR, MTW, MFI, MON, MTF, MWW, NES , OFF, PAU, PHI, RHO, RTE, RTH, STI, STT, TON, TSC, UFI, VNI, WEI, YUG and the like.

Furthermore, as the zeolite having a pore structure of oxygen 12-membered ring or less and oxygen 10-membered ring or more, for example, AEL, AFI, ATO, BEA, EPI, EUO, FER, FAU, HEU, GME, LTL, MOR, MTW. , MEL, MFI, MWW, NES, OFF, STI, TON, WEI and the like.
In the present specification, the structure of the zeolite is indicated by a code that defines the structure of the zeolite defined by International Zeolite Association (IZA) as described above.

The oxygen n-membered ring structure determines the size of the pores of the zeolite, and in zeolites smaller than the oxygen 6-membered ring, the pore size is smaller than the Kinetic diameter of the ethanol molecule, so the permeability of ethanol is reduced and it is practical. Not always.
The framework density (T/1000Å ³ ) of the main zeolite constituting the zeolite membrane is not particularly limited, but is usually 25 or less, preferably 20 or less, more preferably 18 or less, usually 10 or more, preferably 11 or more. , And more preferably 12 or more.

The framework density means the number of elements (T element) other than oxygen constituting the skeleton per 1000Å ³ of zeolite, and this value is determined by the structure of zeolite. The relationship between the framework density and the structure of zeolite is shown in ATLAS OF ZEOLITE FRAMEWORK TYPES Six Revised Edition 2007 ELSEVIER.

When the framework density is at least the above lower limit, the zeolite structure is prevented from becoming weak, the durability of the zeolite membrane becomes high, and it becomes easy to apply to various uses. Further, when the framework density is not more than the above upper limit, diffusion of the substance in the zeolite is not hindered, and the permeation flux of the zeolite membrane tends to be high, which is economically advantageous.

In the present invention, the preferred structure of the main zeolite constituting the zeolite membrane is AEL, AFI, ATO, BEA, EPI, EUO, FER, FAU, HEU, GME, LTL, MOR, MTW, MEL, MFI, MWW, NES, OFF, STI, TON, WEI, more preferable structures are BEA, EUO, FER, FAU, MOR, MTW, MEL, MFI, MWW, NES, and further preferable structures are BEA, FAU, MOR, MEL, MFI, and the most preferred structure is MFI. Among these structures, so-called silicalite containing almost no aluminum is particularly desirable. Silicalite is generally of the MFI type.

The method for removing a trace amount of alcohol using the zeolite membrane composite will be described below.
Specifically, the porous support side or the zeolite membrane side of the zeolite membrane composite is brought into contact with water containing a trace amount of alcohol, and the opposite side has a lower pressure than the side in contact with the water. , Permeates alcohol selectively from water containing a trace amount of alcohol.

Here, the present invention is characterized in that the vapor permeation method (VP method) is used to remove a trace amount of alcohol.
In the vapor permeation method, the zeolite membrane is contacted with a vapor of water containing a small amount of alcohol to permeate the alcohol. Moisture containing a trace amount of alcohol is heated or depressurized, or steam is generated by combining heating and depressurization, the steam is brought into contact with the zeolite membrane, and only alcohol is permeated to remove alcohol from the water. Remove.

By contacting only the vapor with the zeolite membrane, it is possible to avoid insoluble matters such as fibers, starch, and suspended matter and high molecular weight compounds from coming into contact with the zeolite membrane, thereby reducing the fouling of the membrane and preventing clogging. Can be suppressed.
When the separation target is a food-derived product or an alcohol (bioethanol) using a natural material, it may contain impurities other than water and alcohol. Therefore, it is considered that the vapor permeation method is more excellent than the pervaporation method (PV method) in that the permeation amount of the membrane is improved, the treatment efficiency is increased, and the separation performance is excellent.

In the present invention, the alcohol-selective separation membrane can usually remove 30% by mass or more of a trace amount of alcohol in water, preferably 40% by mass or more, more preferably 50% by mass or more, and particularly preferably. It is 60% by mass or more, and most preferably 80% by mass or more.
The alcohol concentration in the alcohol-containing liquid that has passed through the alcohol-selective separation membrane is usually 5% by mass or more, preferably 7% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, particularly preferably It is 20% by mass or more, and usually 100% by mass or less.

Further, the alcohol concentration in the water from which alcohol has been removed is usually less than 10% by mass, preferably less than 5% by mass, more preferably less than 1% by mass, even more preferably less than 0.8% by mass, particularly preferably 0. It is less than 5% by weight, most preferably less than 0.3% by weight.
The separation operation using the alcohol-selective separation membrane may be repeated, and the alcohol-containing liquid that has permeated the zeolite membrane may be separated again by the alcohol-selective separation membrane to remove alcohol to a desired alcohol concentration. Further, the alcohol-containing liquid that has passed through the zeolite membrane may be introduced into the first separation step.

The present invention will be described more specifically by way of examples, but the present invention is not limited to the description of the examples below as long as the gist thereof is not exceeded.

(Example 1)
By hydrothermally synthesizing MFI-type zeolite directly on the inorganic porous support, a zeolite membrane composite of the inorganic porous support and the MFI-type zeolite membrane (silicalite membrane) was prepared.
The following were prepared as a reaction mixture for hydrothermal synthesis.
As an organic template, 57.22 g of water was added with 14.29 g of an aqueous solution of tetrapropylammonium hydroxide (hereinafter referred to as "TPAOH") (containing 40% by mass of TPAOH, manufactured by Sechem), and further colloidal silica (Snowtex 40, 24.83 g (manufactured by Nissan Chemical Co., Ltd.) was added and stirred for 1 hour to obtain a reaction mixture.

The composition of the reaction mixture (molar ratio) _is a _{SiO 2 / Al 2 O 3 /} H 2 O / TPAOH = 1/0/200 / 0.17.
As the inorganic porous support, a cylindrical tubular porous mullite tube (outer diameter 12 mm, inner diameter 9 mm) was cut into a length of 400 mm and air-blown was used.
As the seed crystal, MFI type zeolite crystallized by hydrothermal synthesis at 140° C. for 2 days with a gel composition (molar ratio) of SiO ₂ /H ₂ O/TPAOH=1/20/0.4 was used. The support was immersed in a dispersion liquid in which 1% by mass of this seed crystal was dispersed in water for a predetermined time, and then dried at 120° C. for 2 hours to attach the seed crystal.

The support to which this seed crystal was adhered was vertically dipped in a Teflon (registered trademark) inner cylinder (800 ml) containing the above reaction mixture to seal the autoclave, and allowed to stand still at 160° C. for 24 hours. Heated under autogenous pressure. After a lapse of a predetermined time, the support-zeolite membrane composite was taken out from the reaction mixture after allowing to cool, washed and dried at 120° C. for 2 hours.
The zeolite membrane composite before template firing was fired at 500° C. for 5 hours in an electric furnace. The mass of the MFI-type zeolite crystallized on the support was 34 g/m ² , which was determined from the difference between the mass of the zeolite membrane composite after calcination and the mass of the support.

The air permeation amount of the zeolite membrane composite after firing was 2,725 L/(m ² ·h).
The obtained zeolite membrane composite was cut into a length of 80 mm, and ethanol was selectively permeated by a vapor permeation method to carry out a separation experiment for reducing the ethanol concentration of the liquid to be treated. 99.37 g of an ethanol/water mixed solution (1.75/98.25% by mass) was heated to 50° C. in a flask, and the obtained zeolite membrane composite was placed in a position where it did not come into contact with the liquid. FIG. 1 shows a schematic diagram of the apparatus used. A vacuum was applied to the inside of the zeolite membrane composite to allow ethanol vapor to pass through. The permeated ethanol was collected by a trap cooled with dry ice/ethanol, and the permeation flow rate was calculated from the mass. Further, the collected liquid was analyzed by gas chromatography to measure the composition of the permeated liquid. The permeation flux after 5 hours from the start of measurement was 0.52 kg/(m ² ·h), and the ethanol concentration in the permeate was 10.21% by mass. The permeance of ethanol was 5.14×10 ⁻⁷ mol/(m ² ·s·Pa).

The ethanol concentration in the flask after 5 hours from the start of the measurement was 1.15% by mass, and the liquid amount decreased to 94.70 g. It was possible to concentrate the ethanol concentration from 1.75% by mass to 1.15% by mass by separating the liquid to be treated by the vapor permeation method using the zeolite membrane composite. That is, 37% by mass of ethanol could be removed from the trace amount of alcohol in the liquid to be treated.

(Example 2)
By hydrothermally synthesizing MFI-type zeolite directly on the inorganic porous support, a zeolite membrane composite of the inorganic porous support and the MFI-type zeolite membrane (silicalite membrane) was prepared.
The following were prepared as a reaction mixture for hydrothermal synthesis.
To 119.16 g of water, 2.98 g of an aqueous solution of tetrapropylammonium hydroxide (hereinafter referred to as "TPAOH") (containing 40% by mass of TPAOH, manufactured by Sechem) was added as an organic template, and further colloidal silica (Snowtex 40, Nissan). 5.17 g (manufactured by Kagaku) was added and stirred for 1 hour to obtain a reaction mixture.

The composition of the reaction mixture (molar ratio) _is a _{SiO 2 / Al 2 O 3 /} H 2 O / TPAOH = 1/0/200 / 0.17.
As the inorganic porous support, a cylindrical tubular porous mullite tube (outer diameter 12 mm, inner diameter 9 mm) was cut into a length of 80 mm, washed with water and dried.
As a seed crystal, MFI type zeolite crystallized by hydrothermal synthesis at 140° C. for 2 days with a gel composition (molar ratio) of SiO ₂ /H ₂ O/TPAOH=1/20/0.4 was used. The support was immersed in a dispersion liquid obtained by dispersing the seed crystal in 1% by mass of water for a predetermined time and then dried at 120° C. for 2 hours to attach the seed crystal.

The support to which this seed crystal was adhered was vertically immersed in a Teflon (registered trademark) inner cylinder (200 ml) containing the above reaction mixture to seal the autoclave, and in a static state at 175° C. for 24 hours. Heated under autogenous pressure. After a lapse of a predetermined time, the support-zeolite membrane composite was taken out from the reaction mixture after allowing to cool, washed and dried at 120° C. for 2 hours.
The zeolite membrane composite before template firing was fired at 500° C. for 5 hours in an electric furnace. The mass of the MFI-type zeolite crystallized on the support was 63 g/m ² , which was determined from the difference between the mass of the membrane composite after calcination and the mass of the support.

The air permeation amount of the zeolite membrane composite after firing was 1937 L/(m ² ·h).
Using the obtained zeolite membrane composite, 93.93 g of an ethanol/water mixed solution (1.40/98.60 mass%) was heated to 50° C. in a flask by the vapor permeation method in the same manner as in Example 1. Then, a separation experiment was conducted to selectively permeate ethanol and reduce the ethanol concentration of the liquid to be treated.

The permeation flux after 6 hours from the start of measurement was 0.46 kg/(m ² ·h), and the ethanol concentration in the permeate was 11.55% by mass. The permeance of ethanol was 1.07×10 ⁻⁶ mol/(m ² ·s·Pa).
The ethanol concentration in the flask after 6 hours from the start of the measurement was 0.60% by mass, and the liquid amount was reduced to 89.14 g. By separating the liquid to be treated by the vapor permeation method using the zeolite membrane composite, the ethanol concentration could be concentrated from 1.40% by mass to 0.60% by mass. That is, 59% by mass of ethanol could be removed from the trace amount of alcohol in the liquid to be treated.

DESCRIPTION OF SYMBOLS 1 Apparatus 2 Stirrer 3 Stirrer 4 Hot water bath 5 2 or eggplant type flask 6 Liquid to be treated 7 Zeolite membrane complex 8 Three-way cock 9 Pressure gauge 10 Cold trap 11 Purge valve 12 Vacuum pump

Claims (4)

Aqueous solution containing alcohol is mixed with alcohol content and 10 mass% by adsorbent or membrane separation.
A method of removing alcohol from the water after separation into water containing alcohol below,
Characterized in that the water vapor is brought into contact with a zeolite membrane which is an alcohol-selective separation membrane, and the alcohol is removed from the water by permeating the alcohol by a vapor permeation method.
A method for removing alcohol from water containing 10% by mass or less of alcohol. The water content containing 10% by mass or less of the alcohol is used as the zeolite membrane for silicalite.
Alcohol removed by contact with the membrane and permeation of alcohol by vapor permeation.
Call is not less than 30% by weight prior to transmission, the method of removing the alcohol according to claim 1. The water content containing 10% by mass or less of the alcohol is used as the zeolite film
The content of alcohol in the water content after the alcohol removal by contacting with a silicalite membrane having an amount of 63 g/m ² or more and allowing the alcohol to permeate by a vapor permeation method is less than 1% by mass. The method for removing alcohol according to. The method for removing alcohol according to claim 1, wherein the alcohol is ethanol.

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