WO2010070991A1

WO2010070991A1 - Liquid mixture separation membrane, method for changing composition of liquid mixture using same, and device for separating liquid mixture

Info

Publication number: WO2010070991A1
Application number: PCT/JP2009/069000
Authority: WO
Inventors: 応明河合; 清新木
Original assignee: 日本碍子株式会社
Priority date: 2008-12-19
Filing date: 2009-11-06
Publication date: 2010-06-24

Abstract

A liquid mixture separation membrane, which has high permeation performance and high performance durability, and is used for changing the composition of a liquid mixture after being permeated therethrough by separating operations, from the composition of the liquid mixture when supplied thereto, said liquid mixture containing a hydrocarbon liquid and an alcohol liquid. A method for changing the composition of a liquid mixture, said method using the separation membrane. A device for separating a liquid mixture. The liquid mixture separation membrane is substantially composed of carbon, and is capable of changing the composition of a liquid mixture, which contains a hydrocarbon liquid and an alcohol liquid, by having the liquid mixture permeate therethrough. Specifically, the liquid mixture separation membrane is a carbon membrane which is obtained by carbonizing a resin layer, which serves as the precursor, by thermal decomposition in an oxygen inert atmosphere.

Description

Separation membrane for liquid mixture, method for changing composition of liquid mixture using the same, and liquid mixture separation device

The present invention relates to a separation membrane for a liquid mixture capable of changing the composition of a liquid mixture containing a hydrocarbon liquid and an alcohol liquid, a method for changing the composition of a liquid mixture using the same, and a liquid mixture separation device.

Membrane separation technology has been used in various fields including the field of food and medicine and water treatment from the viewpoint of energy saving and low environmental load. Conventional membrane separation techniques have been dominated by solid / liquid separation, for example, as used in the food field. However, in recent years, the application of membrane separation technology in ethanol production using biomass, that is, enrichment of a specific component (eg water or alcohol in this case) from a liquid mixture, as represented by membrane separation of water and ethanol The liquid separation operation has been performed using a membrane separation technique to change the composition of the liquid mixture.

As described above, the separation operation of the liquid mixture using the membrane separation technology has been developed mainly in the aqueous system, but in recent years, the application to the non-aqueous field such as the oil refining process and the petrochemical industry has been studied. (For example, Patent Documents 1 to 3). For example, Patent Document 2 discloses a separation membrane used for changing the composition of a liquid mixture containing a paraffinic hydrocarbon liquid and an olefinic hydrocarbon liquid by a separation operation.

Regarding membrane separation technology, in addition to the separation of liquid mixtures between hydrocarbons, recently, hydrocarbon liquids have been developed to improve the startability of internal combustion engines in the field of fuels and to achieve high efficiency combustion and cleanliness. Attempts have been made to apply it to the separation of liquid mixtures containing alcohol and alcohol liquids (for example, Patent Documents 4 to 6).

Patent Document 4 discloses a fuel supply device for an internal combustion engine that includes a component adjustment unit that adjusts a fuel component composition by separating an alcohol component from fuel, using a zeolite membrane or a mesoporous silica membrane as a separation membrane. It is disclosed.

Patent Document 5 uses a film made of an inorganic metal oxide and / or a film made of a polymer compound that separates a mixed fuel obtained by adding an ethanol fuel to a hydrocarbon-based fuel into a hydrocarbon-rich fuel and an ethanol-rich fuel. There has been disclosed a fuel supply device having a conventional separation membrane. As the separation membrane, a test result using an MFI zeolite membrane having a thickness of about 25 microns formed on a cordierite plate is disclosed.

Japanese Patent Laid-Open No. 10-180046 Japanese Patent Laid-Open No. 10-180057 JP 2000-157843 A JP 2008-106623 A JP 2007-255226 A Special table 2008-536043

However, these separation membranes did not satisfy the permeation performance of their selectivity and permeation flux (permeate amount).

When the inventors researched and developed a separation membrane with excellent permeation performance, the conventional separation membrane is not only satisfactory in permeation performance, but over time compared to its initial performance. It was found that the permeation performance deteriorates significantly. The cause of the deterioration is not clear, but it is presumed that the alcohols in the liquid mixture are likely to have adverse effects by reacting with the conventional separation membrane material and / or adsorbing on the pores.

The present invention is for a liquid mixture having a high permeation performance and a high performance durability, which is used to change the composition at the time of supplying a liquid mixture containing a hydrocarbon-based liquid and an alcohol liquid by a separation operation and the composition after permeation through a membrane. It is an object of the present invention to provide a separation membrane, a method for changing the composition of a liquid mixture using the separation membrane, and a liquid mixture separation device.

As a result of diligent efforts by the present inventors to solve the above problems, it has been found that a separation membrane consisting essentially of carbon is suitable for separation of a liquid mixture containing a hydrocarbon liquid and an alcohol liquid. That is, according to the present invention, the following separation membrane for a liquid mixture, a method for changing the composition of a liquid mixture using the same, and a liquid mixture separation device are provided.

[1] A separation membrane for a liquid mixture that is substantially composed of carbon and that can change the composition of the liquid mixture by allowing a liquid mixture containing a hydrocarbon-based liquid and an alcohol liquid to pass through.

[2] The separation membrane for liquid mixture according to [1], wherein the separation membrane for liquid mixture contains 50% or more of carbon in a mass ratio.

[3] A carbon film obtained by thermally decomposing a carbon-containing layer as a precursor in an oxygen inert atmosphere, and allowing the liquid mixture containing the hydrocarbon-based liquid and the alcohol liquid to pass through, The separation membrane for liquid mixture according to [1] or [2], wherein the composition of the liquid mixture can be changed.

[4] The separation membrane for liquid mixture according to [3], wherein the carbon-containing layer that is the precursor is a resin layer.

[5] The separation membrane for liquid mixture according to [4], wherein the resin forming the resin layer is at least one selected from the group consisting of a polyimide resin and a phenol resin.

[6] The separation membrane for liquid mixture according to any one of [1] to [5], which is formed on a porous support that supports the separation membrane for liquid mixture.

[7] A method for changing a composition of a liquid mixture, wherein the composition of the liquid mixture is changed by allowing the liquid mixture to permeate through the liquid mixture separation membrane according to any one of [1] to [6].

[8] When the liquid mixture is passed through the separation membrane for liquid mixture from the membrane supply side as a supply liquid mixture, the weight fraction of alcohols in the mixed vapor on the membrane permeation side of the separation membrane for liquid mixture is The method for changing the composition of the liquid mixture according to [7], wherein the composition is higher than the weight fraction of alcohols in the mixed vapor in equilibrium with the supply liquid mixture.

[9] The liquid mixture separation membrane according to any one of [1] to [6] is disposed, and has a porous base material that supports the separation membrane. A separation unit that divides the side space, a supply unit that supplies the liquid mixture to the raw material side space, and a permeate that collects the permeated liquid and / or the permeated gas that has permeated the liquid mixture separation membrane from the permeate side space. A liquid mixture separator including a recovery unit.

[10] The liquid mixture separation device according to [9], wherein the permeation recovery unit includes a cooling device that liquefies the permeated gas.

According to the separation membrane for a liquid mixture, the method for changing the composition of the liquid mixture, and the liquid mixture separation device of the present invention, the components of the liquid mixture containing the hydrocarbon liquid and the alcohol liquid can be changed. The separation membrane for a liquid mixture of the present invention has excellent permeation performance (selectivity and permeation flux) and high performance durability.

It is a figure which shows one Embodiment of the separation membrane arrangement | positioning body by which the separation membrane for liquid mixtures of this invention was arrange | positioned. It is sectional drawing of the end surface of a porous base material before arrangement | positioning a separation membrane, and outer peripheral surface vicinity. It is sectional drawing of the end surface of the porous base material which arrange | positioned the separation membrane, and outer peripheral surface vicinity. It is sectional drawing which shows the module made from SUS provided with the porous base material by which the separation membrane of this invention was arrange | positioned. It is a schematic diagram which shows one Embodiment of a liquid mixture separator. It is a graph which shows the permeability coefficient of a separation membrane. It is a schematic diagram which shows the apparatus used for the permeation | transmission test of single component gas.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

The separation membrane 11 for a liquid mixture of the present invention is a separation membrane that is substantially made of carbon and that can change the composition of the liquid mixture before and after permeation by allowing a liquid mixture containing a hydrocarbon liquid and an alcohol liquid to permeate. is there. More specifically, it is a porous carbon film substantially made of carbon disposed on the surface of the porous substrate 1. In this specification, “consisting essentially of carbon” means containing 50% or more of carbon in a mass ratio.

The composition change method of the liquid mixture of the present invention is a method of changing the composition of the liquid mixture using the liquid mixture separation membrane 11. The liquid mixture that can be used in the composition changing method of the present invention includes a hydrocarbon-based liquid and an alcohol liquid. The hydrocarbon liquid can be classified into paraffins, olefins, naphthenes, aromatics, etc., but n-pentane, n-hexane, n-heptane, n-octane, n-dodecane, 2-methylbutane, 1 -Pentene, 1-hexene, 1-octene, cyclopentane, cyclohexane, benzene, toluene, o-xylene, m-xylene, p-xylene and the like. Examples of the alcohol liquid include methanol, ethanol, 1-propanol, 2-propanol, n-butanol, and 2-butanol.

FIG. 1 shows an embodiment of a separation membrane assembly 100 in which a separation membrane 11 for liquid mixture of the present invention (also simply referred to as a separation membrane 11) is disposed. A separation membrane 11 is formed on the inner wall surface 5 of the through-hole 2 formed along the longitudinal direction 60 of the monolithic porous substrate 1, and seal portions 12 are disposed on both end surfaces 4 and 4 (FIG. 3). The seal portion 12 is disposed so as not to block the through-hole 2 over the entire end faces 4 and 4 of the porous substrate 1 (monolith-shaped substrate 1a).

The separation membrane arrangement body 100 allows the liquid mixture to flow into the through-hole 2 from the opening 51 of the through-hole 2 of the monolithic substrate 1a, and a part of the liquid mixture (passing fluid) passes through the inner wall surface 5 of the through-hole 2. The liquid mixture is separated by passing through the separation membrane 11 disposed on the inside and flowing into the monolith-shaped substrate 1a and discharging it from the side surface 3 of the monolith-shaped substrate 1a. The liquid mixture flows from the end surface 4 of the monolithic substrate 1 a into the monolithic substrate by the seal portion 12, and the fluid passing through the separation membrane 11 and the liquid mixture flowing from the end surface 4 are mixed together from the side surface 3. Prevent spillage.

The separation membrane 11 of the present invention is preferably a carbon membrane obtained by carbonizing a precursor carbon-containing layer by thermal decomposition in an oxygen inert atmosphere. The thermal decomposition is preferably performed at 400 to 1000 ° C., more preferably 450 to 900 ° C. The oxygen inert atmosphere refers to an atmosphere in which a precursor for forming a carbon film is not oxidized even when heated in the above temperature range. Specifically, an atmosphere such as an inert gas such as nitrogen or argon or a vacuum is used. Say.

The precursor for forming a carbon film by thermal decomposition is not particularly limited as long as it contains carbon, but examples thereof include polyethylene glycol, ethyl cellulose, and other resins. As the resin, for example, a resin mainly composed of a polyimide resin, a phenol resin, a polyamideimide resin, or the like can be preferably used. Here, a main component means the component contained 50 mass% or more of the whole.

The thickness of the carbon film is preferably 0.05 to 5.0 μm, more preferably 0.05 to 1.0 μm. When the thickness is less than 0.05 μm, defects may occur in the carbon film, and when the thickness is more than 5.0 μm, the permeation flux when the mixture is separated may be reduced. The average pore diameter of the carbon film is preferably 0.2 to 100 nm, and more preferably 0.2 to 10 nm. The average pore diameter can be measured by a gas adsorption method.

In the separation membrane assembly 100 of the present embodiment, the porous substrate 1 can be made of any material such as metal and ceramics as long as the strength, permeation performance, corrosion resistance, etc. are sufficient. Alumina particles having an average particle size of 0.3 to 10 μm are deposited on a substrate, which is a monolithic alumina porous substrate having a size of 10 to 100 μm and an average pore size of 1 to 30 μm, by filtration, and then fired to obtain a thickness of 10 to After forming a first surface dense layer having an average pore diameter of 1000 to 3 μm and further depositing alumina particles having an average particle diameter of 0.03 to 1 μm on the first surface dense layer by filtration film formation, The second surface dense layer having a thickness of 1 to 100 μm and an average pore diameter of 0.01 to 0.5 μm is preferably formed by firing. Further, the porosity is preferably 20 to 80%, and more preferably 30 to 70%. The particles constituting the porous substrate 1 are preferably ceramic particles, and specifically, alumina particles, silica particles, cordierite particles, zirconia particles, mullite particles, and the like are preferable.

The shape of the porous substrate 1 is not particularly limited, and the shape is determined according to the purpose, such as a disk shape, a polygonal plate shape, a cylinder shape such as a cylinder or a square tube, a column shape such as a column or a prism. Can do. The size of the porous substrate is not particularly limited, and the size of the porous substrate can be determined according to the purpose as long as it satisfies the required strength as a support and does not impair the permeability of the fluid to be separated. it can. Since the ratio of the membrane area to the volume is large, a monolith shape is particularly desirable. “Monolith-shaped substrate” refers to a lotus-like or honeycomb-shaped substrate having a plurality of through holes formed in the longitudinal direction 60.

Examples of the seal portion 12 include a glass seal and a metal seal. Among these, a glass seal is preferable because it is easy to match the thermal expansion coefficient with the porous substrate. Although it does not specifically limit as a physical property of the glass used for a glass seal, It is preferable to have a thermal expansion coefficient near the thermal expansion coefficient of a porous base material. The glass used for the glass seal is preferably lead-free glass that does not contain lead.

Next, a method for producing the separation membrane 11 for liquid mixture of the present invention will be described. In advance, the porous base material 1 serving as the base material for forming the separation membrane 11 is manufactured by extrusion molding and baking in the conventional manufacturing method of the porous monolithic base material 1a.

Next, a glass paste is applied to both end faces 4 and 4 of the porous substrate 1 and heated at a predetermined temperature to form a seal portion 12 as shown in FIG. First, a glass paste is applied to the surface of the porous substrate 1. The part to which the glass paste is applied is not particularly limited, and gas, liquid, fine particles in the surface of the porous substrate 1 from the porous substrate 1 to the outside, or from the outside to the porous substrate 1. It is preferable to apply to the part which is going to prevent that etc. move. In the present embodiment, a glass paste is applied to both

end surfaces

4 and 4 of the porous substrate 1 (monolithic substrate 1a).

As the glass material applied to the surface of the porous substrate 1 as a glass paste, lead-free glass containing no lead is preferable. Further, the glass material preferably has a softening point of 600 to 1000 ° C., more preferably 700 to 1000 ° C. If the temperature is lower than 600 ° C., the glass may be melted during heating in the formation process of the separation membrane 11. If the temperature is higher than 1000 ° C., the sintering of the particles constituting the porous substrate 1 proceeds more than necessary. May end up. The glass paste can be produced by dispersing powdered glass in a solvent such as water. Alternatively, the polymer may be added in addition to a solvent such as water.

Next, a film forming step for forming a film made of a precursor solution for forming the separation film 11 on the porous substrate 1 is performed. In the film forming step, the method of passing the precursor solution through the through-hole 2 of the monolith-shaped substrate 1a may be any method as long as the film thickness becomes uniform, and is not particularly limited. Preferably, it can be mentioned.

It is preferable to use a polyimide solution and / or a phenol solution as a precursor solution for forming a separation membrane used for film formation in the film formation step in one embodiment of the present invention. The polyimide solution and / or phenol solution is obtained by dissolving polyimide resin and / or phenol resin in a suitable organic solvent such as N-methyl-2-pyrrolidone (NMP). The concentration of the polyimide and / or phenol in the polyimide solution and / or phenol solution is not particularly limited, but is preferably 1 to 15% by mass from the viewpoint of making the solution easy to form a film.

Next, a drying process for drying the film (coat layer) made of the precursor solution is performed. In the drying step, for example, the film made of the precursor solution is ventilated while passing hot air from the opening 51 on one end face 4 to the opening 51 on the other end face 4.

After the drying step, a heat treatment step (carbonization) is performed on the polyimide film and / or the phenol film in a vacuum or in an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere. By carbonizing by thermal decomposition in a temperature range of about 400 to 1000 ° C., a separation membrane 11 (carbon membrane) as shown in FIG. 3 is obtained. That is, the separation membrane 11 is obtained by carbonizing the precursor resin layer by thermal decomposition in an oxygen inert atmosphere. In general, when carbonization is performed at a temperature of less than 400 ° C., the polyimide membrane and / or the phenol membrane are not sufficiently carbonized, and the selectivity as a molecular sieve membrane and the permeation rate are lowered. On the other hand, when carbonization is performed at a temperature exceeding 1000 ° C., the permeation rate decreases due to shrinkage of the pore diameter.

The composition change method of the liquid mixture of the present invention is a method of changing the composition of the liquid mixture using the liquid mixture separation membrane 11 described above. The liquid mixture may be supplied as a liquid to allow gas permeation (permeation vaporization method, pervaporation method), or the liquid may be once vaporized by heating to allow gas permeation (vapor permeation method). Further, gas may be permeated by heating until a part of the liquid is vaporized.

Specifically, it can be performed using a mixture separation apparatus 101 as shown in FIGS. That is, the liquid mixture separation apparatus 101 of the present invention includes a separation unit that partitions the raw material side space and the permeation side space, a supply unit that supplies the liquid mixture to the raw material side space, and a separation membrane for the liquid mixture from the permeation side space. A permeation recovery unit that recovers the permeated liquid and / or the permeated gas. The separation unit is constituted by a SUS module 37 having the porous substrate 1 that includes the liquid mixture separation membrane 11 described above and supports the separation membrane 11. The supply unit is constituted by a raw material tank 35 and a circulation pump 36, and the permeation recovery unit is constituted by a cooling trap 38 and a vacuum pump 39 which are cooling devices.

The raw material tank 35 heats and holds a liquid mixture (raw material) containing a hydrocarbon-based liquid and an alcohol liquid, which is placed in the tank, at a predetermined temperature (for example, 50 ° C.).

The SUS module 37 has a supply liquid introduction port 37a and a supply liquid discharge port 37b so as to communicate with the raw material side space 31, and the permeate vapor recovery for discharging the permeate vapor to the outside in the permeation side space 32. A mouth 37c is formed. The liquid mixture in the raw material tank 35 is configured to be supplied to the raw material side space 31 of the SUS module 37 by the circulation pump 36.

The SUS module 37 is configured such that the monolithic base material 1a on which a carbon film is formed can be placed at predetermined positions on both outer peripheral portions thereof via o-rings 33. The SUS module 37 is partitioned into the raw material side space 31 and the permeation side space 32 by the o-ring 33, the glass seal (seal part 12) and the separation membrane 11.

A cooling trap 38 and a vacuum pump 39 are provided on the permeate vapor recovery port 37c side of the SUS module 37, and the permeate vapor discharged from the permeate vapor recovery port 37c is collected by the liquid N ₂ trap. Yes.

With the above configuration, the raw material is supplied to the raw material side space 31 of the SUS module 37 by the circulation pump 36 from the supply liquid introduction port 37a, and the raw material discharged from the supply liquid discharge port 37b is returned to the raw material tank 35. Circulate. In the method for separating a liquid mixture of the present invention, the above-mentioned liquid mixture is used as a raw material. Using this liquid mixture as a supply mixture from the supply introduction port 37a, at least a part of the supply mixture is brought into contact with the membrane supply side 11a of the separation membrane in a liquid state. By depressurizing the support side of the separation membrane 11 with the vacuum pump 39, the permeated vapor that permeates to the membrane permeation side 11b of the separation membrane 11 and is discharged from the permeated vapor recovery port 37c is recovered by the liquid N ₂ trap. The degree of vacuum in the transmission side space 32 is controlled by a pressure controller under a predetermined reduced pressure (for example, about 0.5 Torr). Thereby, the composition of the liquid mixture can be changed.

By the way, when a known zeolite membrane or mesoporous silica membrane is used in the separation of a liquid mixture containing a hydrocarbon-based liquid and an alcohol liquid, not only the permeation performance is satisfactory, but the initial performance is 6%. The inventors have found that the permeation performance is remarkably deteriorated after about an hour. In the case of using a zeolite membrane or mesoporous silica membrane, separation with a liquid mixture of hydrocarbon liquids (for example, a liquid mixture of n-heptane and toluene, and a mixture of n-octane and o-xylene) changes with time. It was speculated that the alcohol component in the mixed liquid had some adverse effects. Specifically, zeolite membranes and mesoporous silica membranes are composed of silicon elements, which may react with alcohols, or alcohols are materials of silicon elements such as zeolite membranes and mesoporous silica membranes. It may have an adverse effect such as adsorbing and blocking the pores. On the other hand, the carbon membrane can solve the above problems in the separation of a liquid mixture containing a hydrocarbon-based liquid and an alcohol liquid.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Examples 1 to 5)
<Preparation of porous substrate>
Extruded porous alumina columnar substrate (monolithic substrate 1a) having a diameter of 30 mm and a length of 160 mm provided with 55 through straight holes (through holes 2) having a diameter of 2.5 mm along the longitudinal direction 60 It was produced by molding and firing. Furthermore, both ends 4 and 4 of the monolith-shaped substrate 1a were sealed by melting glass (seal part 12) and subjected to a later test (see FIG. 2).

<Production of carbon film>
A solution obtained by dissolving a commercially available polyimide resin (U varnish S manufactured by Ube Industries Co., Ltd.) in a solvent was dip coated on the inner surface of the through straight hole 2 of the monolithic substrate 1a to form a coat layer. Hot air was blown into the through straight holes 2 to dry the solvent roughly, and then dried in the air at 300 ° C. for 1 hour. This process was repeated four times, and a resin layer was formed on the inner surface of the through straight hole 2 of the monolithic substrate 1a. In order to check whether or not the formed resin layer is covered over the entire surface of the through-hole linear hole, one end face 4 of the monolith-shaped substrate 1a is closed and evacuated from the opposite end face 4 with a commercially available rotary vacuum pump. It was confirmed that the pressure reached 100 Pa or less. The monolith-shaped substrate 1a on which the resin layer is formed is heat-treated at 600 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate 300 ° C./h) to carbonize the resin layer, whereby the through-hole 2 of the monolith-shaped substrate 1a. A carbon membrane (separation membrane 11) formed on the inner surface was obtained. When the carbon content of the carbon film was measured by a fully automatic elemental analyzer, it was 70% or more. The film thickness of the carbon film was about 0.5 microns from cross-sectional observation by SEM.

<Transmission coefficient>
The permeability coefficient (pressure 0.1 MPa) of the membrane (the membranes of Examples 1 to 5) was determined using various single component gases. Using the apparatus shown in FIG. 7, a single component gas permeation test was performed. The monolithic substrate 1a on which the carbon film is formed is placed in a predetermined position (SUS module 137) in which the monolithic base material 1a is housed in a SUS casing through o-rings 133 at both ends. The SUS module 137 is partitioned into a gas supply side space 131 and a gas permeation side space 132 by the o-ring 133, the glass seal (seal part 12) and the separation membrane 11. Since the gas supply side space 131 is closed at the subsequent stage of the SUS module 137, gas is supplied from the supply gas introduction port 137 a to the supply side space 131 of the SUS module 137 with an evaluation gas cylinder connected to the supply side. The gas supplied and discharged from the supply gas discharge port 137b stays and gives a predetermined pressure to the membrane. In this experiment, the gas supply side space 131 was 0.1 MPa in gauge pressure, and the permeation side space 132 was atmospheric pressure. After confirming that the permeation flow rate was stable, the gas permeation coefficient (gas permeation coefficient (nmol / Pa · m ² · s) was measured with a dry gas meter or soap film flow meter provided on the gas recovery port 137c side for a certain time. “Nmol” indicates “10 ⁻⁹ mol.” The results are shown in FIG.6 and Table 1. A result that a gas having a molecular diameter equal to or smaller than the molecular diameter of N ₂ has a large permeability coefficient was obtained.

<Membrane performance evaluation test, pervaporation test>
Using the apparatus (mixture separation apparatus 101) shown in FIG. 5, a pervaporation test was performed, and the performance of the membrane was evaluated. A liquid mixture containing a hydrocarbon-based liquid and an alcohol liquid (having a sufficient capacity for the apparatus system) placed in the raw material tank 35 was heated and held at a predetermined temperature (for example, 50 ° C.). The monolithic substrate 1a on which the carbon film was formed was placed in a predetermined position (SUS module 37) in which the monolith-shaped substrate 1a was housed in a SUS casing through o-rings 33 at both ends.

The raw material (liquid mixture) is supplied from the supply liquid introduction port 37a to the raw material side space 31 of the SUS module 37 by the circulation pump 36, and the raw material discharged from the supply liquid discharge port 37b is returned to the raw material tank 35. Was circulated. The linear velocity during circulation was 1.4 m per second. By reducing the pressure on the support side of the separation membrane 11 with the vacuum pump 39, the permeated vapor that permeated the separation membrane 11 and discharged from the permeated vapor recovery port 37c was recovered with a liquid N ₂ trap. The degree of vacuum in the transmission side space 32 was controlled by a pressure controller under a predetermined reduced pressure (for example, about 0.5 Torr). The initial permeation flux was calculated by averaging the total recovered amount in 30 minutes after 30 minutes from the start of the test. Further, with 5 hours and 30 minutes after the start of the test as a starting point, the total recovered amount in the subsequent 30 minutes was averaged to calculate the permeation flux after 6 hours.

The permeation vaporization (pervaporation) test was performed with the apparatus, and the liquefied product of the permeated vapor collected in the liquid nitrogen trap was subjected to gas chromatography analysis to quantify the composition of the permeated vapor. Similar to the permeation flux, the initial vapor composition and the vapor composition after 6 hours were measured. From the above, membrane performance evaluation (separability, permeation flux) was performed.

(Example 1)
O-Xylene (reagent) was selected as the hydrocarbon-based liquid, and ethanol (reagent) was selected as the alcohol liquid, and a mixture of 50% by mass each was used as the feed liquid (raw material, liquid mixture). The feed liquid temperature (= the temperature of the entire system can be considered) was controlled to 50 ° C., and the degree of vacuum in the transmission side space was controlled to 0.5 torr. As a result, the initial composition of the permeate side vapor was 3% by mass of o-xylene and 97% by mass of ethanol. Further, the initial permeation flux (permeated vapor amount per unit membrane area per unit time) at that time was 0.5 kg / m ² h. Since the preliminary test revealed that the ethanol fraction of the vapor equilibrated with the feed liquid was about 92% by mass, separation exceeding the vapor-liquid equilibrium was realized. Further, the vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.5 kg / m ² h which was the same as the initial value.

(Example 2)
The same test as in Example 1 was conducted, except that o-xylene (reagent) was selected as the hydrocarbon liquid and n-butanol (reagent) was selected as the alcohol liquid, and 50% by mass of each was used as the feed liquid. It was. As a result, the initial composition of the permeate side vapor was 9% by mass of o-xylene and 91% by mass of butanol. Further, the permeated vapor flux (permeated vapor amount) at that time was 0.3 kg / m ² h. Since preliminary tests revealed that the n-butanol fraction of the vapor equilibrated with the feed liquid was about 56% by mass, separation exceeding the vapor-liquid equilibrium was realized. Further, the vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.3 kg / m ² h which was the same as the initial value.

Example 3
The same test as in Example 1 was performed except that the temperature of the supply liquid was set to 70 ° C. As a result, the initial composition of the permeate side vapor was 3% by mass of o-xylene and 97% by mass of ethanol. Further, the initial permeation flux at that time was 0.7 kg / m ² h. Since the preliminary test revealed that the ethanol fraction of the vapor equilibrated with the feed liquid was about 75% by mass, separation exceeding the vapor-liquid equilibrium was realized. Further, the vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.7 kg / m ² h which was the same as the initial value.

(Example 4)
N-octane (reagent) and o-xylene (reagent) were selected as the hydrocarbon-based liquid, and ethanol (reagent) was selected as the alcohol liquid, and a mixture of 33.3% by mass was used as the feed solution. The feed liquid temperature (= the temperature of the entire system can be considered) was controlled to 50 ° C., and the degree of vacuum in the transmission side space was controlled to 0.5 torr. As a result, the initial composition of the permeate side vapor was 2% by mass of n-octane, 5% by mass of o-xylene, and 93% by mass of ethanol. Further, the initial permeation flux at that time was 0.4 kg / m ² h. Since preliminary tests revealed that the ethanol fraction of the vapor equilibrated with the feed liquid was about 70% by mass, separation exceeding the vapor-liquid equilibrium was realized. Further, the vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.4 kg / m ² h, which was the same as the initial value.

(Example 5)
The same test as in Example 4 was performed except that the transmission side vacuum was controlled at 450 torr. As a result, the initial composition of the permeate side vapor was 3% by mass of n-octane, 8% by mass of o-xylene, and 89% by mass of ethanol. The initial permeation flux at that time was 0.05 kg / m ² h. Since preliminary tests revealed that the ethanol fraction of the vapor equilibrated with the feed liquid was about 70% by mass, separation exceeding the vapor-liquid equilibrium was realized. Further, the vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.04 kg / m ² h.

(Example 6)
In <Production of carbon film>, a carbon film was produced in the same manner except that the thermal decomposition temperature of the resin layer was set to 450 ° C. When the carbon content of the carbon film was measured, it was 50% or more. The film thickness of the carbon film was about 1 micron.

The test was performed in the same manner as in Example 1 except that the carbon films having different thermal decomposition temperatures in the production method were used. As a result, the initial composition of the permeate side vapor was 5% by mass of o-xylene and 95% by mass of ethanol. Further, the initial permeation flux at that time was 0.4 kg / m ² h. Since the preliminary test revealed that the ethanol fraction of the vapor equilibrated with the feed liquid was about 92% by mass, separation exceeding the vapor-liquid equilibrium was realized. The vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.4 kg / m ² h.

(Example 7)
In <Production of carbon film>, a carbon film was produced in the same manner except that the raw material resin was a commercially available phenol resin (Perval S899 manufactured by Airwater) and the thermal decomposition temperature of the resin layer was 550 ° C. When the carbon content of the carbon film was measured, it was 90% or more. The film thickness of the carbon film was about 0.5 microns. The permeability coefficient (pressure 0.1 MPa) of the membrane was determined using various single component gases. The results are shown in FIG.

The test was performed in the same manner as in Example 4 except that the above carbon film having a different kind of raw material resin and a different thermal decomposition temperature was used. As a result, the initial composition of the permeate side vapor was 1% by mass of n-octane, 2% by mass of o-xylene, and 97% by mass of ethanol. Further, the initial permeation flux at that time was 0.7 kg / m ² h. Since preliminary tests revealed that the ethanol fraction of the vapor equilibrated with the feed liquid was about 70% by mass, separation exceeding the vapor-liquid equilibrium was realized. Further, the vapor composition after 6 hours was almost the same as the initial composition, and the permeation flux after 6 hours was 0.7 kg / m ² h which was the same as the initial value.

(Comparative Examples 1 and 2 (MFI zeolite membrane))
An MFI zeolite membrane was obtained as follows.

(Preparation of seeding sol)
A mixture of 31.22 g of a 40% by mass tetrapropylammonium hydroxide solution (manufactured by SACHEM) and 16.29 g of tetrapropylammonium bromide (manufactured by Wako Pure Chemical Industries, Ltd.), and further 71.25 g of distilled water, about 30 82% by mass of silica sol (trade name: Snowtech S, Nissan Chemical Co., Ltd.) was added and stirred at room temperature to obtain a seeding sol.

(Formation of zeolite seed crystals)
The obtained seeding sol is placed in a stainless steel 300 ml pressure vessel in which a fluororesin inner cylinder is disposed, and the monolith-shaped substrate having a diameter of 30 mm and a length of 160 mm is immersed in the sol for 110 hours at 110 ° C. Reacted. The support after the reaction was dried at 80 ° C. after boiling and washing. It was confirmed by X-ray diffraction of the crystal particles after the reaction that MFI-type zeolite was deposited and present on the inner surface of the through-holes of the monolithic substrate.

(Preparation of film-forming sol)
40% by mass of tetrapropylammonium hydroxide solution (manufactured by SACHEM) 0.80 g and tetrapropylammonium bromide (manufactured by Wako Pure Chemical Industries, Ltd.) 0.42 g were mixed, and further distilled water 193.26 g, about 30 masses. 6.3 g of% silica sol (trade name: Snowtex S, manufactured by Nissan Chemical Co., Ltd.) was added and stirred with a magnetic stirrer at room temperature for 30 minutes to obtain a film-forming sol.

(Formation of zeolite membrane)
The obtained film-forming sol was placed in a stainless steel 300 ml pressure-resistant container having a fluororesin inner cylinder disposed therein in the same manner as described above, and the porous alumina monolith-shaped substrate on which the zeolite seed crystals were deposited Was immersed and reacted at 160 ° C. for 24 hours. The support after the reaction was dried at 80 ° C. for 16 hours after boiling and washing 5 times. For the purpose of growing a zeolite membrane, the above operations of (formation of zeolite membrane) were repeated again. The monolith-shaped substrate was heat-treated in the atmosphere at 500 ° C. for 4 hours to remove tetrapropylammonium, and an MFI-type zeolite membrane formed on the inner surface of the through straight hole of the monolith-shaped substrate was obtained. The thickness of the MFI zeolite membrane was about 12 microns.

(Comparative Example 1 (MFI zeolite membrane))
N-octane (reagent) and o-xylene (reagent) were selected as the hydrocarbon-based liquid, and ethanol (reagent) was selected as the alcohol liquid, and a mixture of 33.3% by mass was used as the feed solution. The feed liquid temperature (= the temperature of the entire system can be considered) was controlled to 50 ° C., and the degree of vacuum in the transmission side space was controlled to 0.5 torr. As a result, the initial composition of the permeate side vapor was 46% by mass of n-octane, 8% by mass of o-xylene, and 46% by mass of ethanol. Further, the initial permeation flux at that time was 0.03 kg / m ² h. Further, after 6 hours, the vapor composition was almost the same as the initial composition, but after 6 hours, the permeation flux rapidly decreased during the test to 0.01 kg / m ² h.

(Comparative Example 2 (MFI zeolite membrane))
The same test as in Comparative Example 1 was conducted, except that o-xylene (reagent) was selected as the hydrocarbon liquid and n-butanol (reagent) was selected as the alcohol liquid, and 50% by mass of each was used as the feed liquid. It was. As a result, the initial composition of the permeate side vapor was 51% by mass of o-xylene and 49% by mass of n-butanol. The initial permeation flux at that time was 0.02 kg / m ² h. Further, the vapor composition after 6 hours was almost the same as the initial composition, but after 6 hours, the permeation flux rapidly decreased during the test to 0.004 kg / m ² h.

(Comparative Example 3 (DDR zeolite membrane))
Using the manufacturing method disclosed in Japanese Patent Application Laid-Open No. 2004-066188, a DDR zeolite membrane formed on the inner surface of the straight through hole of the monolith-shaped substrate was obtained. The thickness of the DDR zeolite membrane was about 10 microns.

As a result of the test using the same supply liquid, temperature, and vacuum as in Comparative Example 1, the initial composition of the permeate side vapor was n-octane 36 mass%, o-xylene 39 mass%, and ethanol 25 mass%. Further, the initial permeation flux at that time was 0.08 kg / m ² h. However, the vapor composition after 6 hours was almost the same as the initial composition, but after 6 hours, the permeation flux rapidly decreased during the test to 0.01 kg / m ² h.

(Comparative Example 4 (mesoporous silica film))
Based on the manufacturing method disclosed in Example 3 of WO2007 / 094267, silica sol was applied and heat-treated to obtain a mesoporous silica film formed on the inner surface of the through-hole of the monolithic substrate. The mesoporous silica film had a thickness of about 0.5 microns.

As a result of the test using the same supply liquid, temperature, and vacuum as in Comparative Example 1, the initial composition of the permeate side vapor was 48 mass% n-octane, 49 mass% o-xylene, and 3 mass% ethanol. The initial permeation flux at that time was 0.02 kg / m ² h. However, it was confirmed that the amount of recovered permeated steam decreased sharply during the subsequent test, and a recovered amount sufficient to measure the composition and permeated amount was not obtained after 6 hours.

The separation membranes of Examples and Comparative Examples are summarized in Table 2, and the test results are summarized in Tables 3 to 4.

As shown in the table, in the separation membranes of Examples 1 to 7, it was possible to separate the liquid mixture of hydrocarbon liquid and alcohol liquid. On the other hand, the separation membranes of Comparative Examples 1 to 4 could not be sufficiently separated. In Examples 1 to 7, the initial permeate vapor flux was larger than those of Comparative Examples 1 to 4, and hardly changed after 6 hours, and was durable.

The separation membrane for liquid mixture, the method for changing the composition of the liquid mixture, and the liquid mixture separation device of the present invention can be used to change the components of the liquid mixture including hydrocarbon liquid and alcohol liquid.

1: porous substrate, 1a: monolith-shaped substrate, 2: through hole (through straight hole), 3: side surface, 4: end surface, 5: inner wall surface, 11: separation membrane, 11a: membrane supply side, 11b: Membrane permeation side, 12: seal part, 31: raw material side space, 32: permeation side space, 33: o-ring, 35: raw material tank, 36: circulation pump, 37: module made by SUS, 37a: supply liquid inlet, 37b: Supply liquid discharge port, 37c: Permeate vapor recovery port, 38: Cooling trap, 39: Vacuum pump, 51: Opening, 60: Longitudinal direction, 100: Separation membrane arrangement, 101: Mixture separation device, 131: Gas supply side space, 132: permeation side space, 133: o-ring, 137: SUS module, 137a: supply gas introduction port, 137b: supply gas discharge port, 137c: gas recovery port.

Claims

A separation membrane for a liquid mixture, which is substantially composed of carbon and can change the composition of the liquid mixture by allowing a liquid mixture containing a hydrocarbon-based liquid and an alcohol liquid to pass through.
The separation membrane for liquid mixture according to claim 1, wherein the separation membrane for liquid mixture contains 50% or more of carbon in a mass ratio.
A carbon film obtained by thermally decomposing a carbon-containing layer as a precursor under an oxygen inert atmosphere, and allowing the liquid mixture containing the hydrocarbon-based liquid and the alcohol liquid to permeate the liquid mixture. The separation membrane for a liquid mixture according to claim 1, wherein the composition of the liquid mixture can be changed.
The separation membrane for a liquid mixture according to claim 3, wherein the carbon-containing layer that is the precursor is a resin layer.
The separation membrane for a liquid mixture according to claim 4, wherein the resin forming the resin layer is at least one selected from the group consisting of a polyimide resin and a phenol resin.
The separation membrane for liquid mixture according to any one of claims 1 to 5, which is formed on a porous support that supports the separation membrane for liquid mixture.
A method for changing a composition of a liquid mixture, wherein the composition of the liquid mixture is changed by allowing the liquid mixture to permeate the separation membrane for a liquid mixture according to any one of claims 1 to 6.
When the liquid mixture is permeated into the liquid mixture separation membrane from the membrane supply side as a supply liquid mixture, the weight fraction of alcohols in the mixed vapor on the membrane permeation side of the liquid mixture separation membrane is the supply mixture. 8. The method of changing the composition of a liquid mixture according to claim 7, wherein the composition is higher than the weight fraction of alcohols in the mixed vapor equilibrated with the liquid mixture.
A separation membrane for a liquid mixture according to any one of claims 1 to 6 is provided, and has a porous base material that supports the separation membrane, and the raw material side space and the permeation side space are separated by the porous base material. A separating section to partition;
A supply unit for supplying the liquid mixture to the raw material side space;
A liquid mixture separation device comprising: a permeate and / or a permeate collection unit that collects a permeate and / or a permeate gas that has permeated through the liquid mixture separation membrane from the permeate space.
10. The liquid mixture separation device according to claim 9, wherein the permeation recovery unit includes a cooling device that liquefies the permeated gas.