JP2023153094A - Evaluation method for permeation amount of organic compound in porous support-zeolite membrane complex - Google Patents

Abstract

To provide a method that can previously evaluate a leak amount of an organic compound from porous support-zeolite membrane complex.SOLUTION: A method according to the present invention evaluates a permeation amount Qa60 of a water-soluble organic compound permeating through porous support-zeolite membrane complex from a water-soluble organic compound solution with a specific water content concentration. The permeation amount Qa60 is evaluated from a measured value of a permeation amount Qb on the basis of a predetermined correlation relationship of the permeation amount Qb such that humidified air with a specific relative humidity permeates through a zeolite membrane and the permeation amount Qa60.SELECTED DRAWING: None

Description

The present invention relates to a method for evaluating the amount of permeation of a water-soluble organic compound through a porous support-zeolite membrane composite.

Zeolite membranes are used as separation membranes to separate and remove water from aqueous solutions of organic compounds. As a method for manufacturing a zeolite membrane, a method is known in which a zeolite membrane is formed by hydrothermal synthesis in the presence of a seed crystal without using an organic template (for example, see Patent Document 1). This method does not require a firing step to remove the organic template after film formation, so an untreated zeolite film can be obtained. Furthermore, an inorganic porous support-zeolite membrane composite having a CHA type zeolite crystal layer on the surface of a porous support of a ceramic sintered body is known (see, for example, Patent Document 2). Since the composite is manufactured by synthesizing a zeolite membrane using an organic template and then performing a calcination treatment, a treated zeolite membrane is obtained. Furthermore, a method for detecting defects in the zeolite membrane is to draw a vacuum on one main surface of the zeolite membrane and measure the degree of vacuum with a vacuum gauge on the other main surface of the zeolite membrane to detect defects in the zeolite membrane. is known (for example, see Patent Document 3).

International Publication No. 2015/159986 International Publication No. 2010/098473 Japanese Patent Application Publication No. 2013-034994

A zeolite membrane is sometimes used as a separation membrane for separating and removing water from an aqueous solution of an organic compound in the form of a composite supported on a porous support. In order to easily evaluate the quality after production, there is a need for a technology that can evaluate in advance the separation performance of a zeolite membrane in a porous support-zeolite membrane composite. As mentioned above, there are known techniques that can detect defects in zeolite membranes in the state of porous support-zeolite membrane composites, but there are no known techniques that can evaluate the separation performance of zeolite membranes in advance. .

One aspect of the present invention is to provide a method that allows the amount of water-soluble organic compounds permeated through a porous support-zeolite membrane composite to be evaluated in advance.

In order to solve the above-mentioned problems, an evaluation method according to one embodiment of the present invention provides a method for evaluating water-soluble organic A method for evaluating the amount of permeation of a compound,
(1) a pretreatment step of controlling the humidity of the zeolite membrane in the porous support-zeolite membrane composite;
(2) measuring the amount of humidified air having a specific relative humidity permeating the porous support-zeolite membrane composite; and
(3) Based on a predetermined correlation between the permeation amount of the humidified air having the specific relative humidity and the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution, the water-soluble organic compound Evaluating the amount of water-soluble organic compounds in the aqueous solution permeating through the zeolite membrane from the measured value of the permeation amount of the humidified air;
including;
When the porous support-zeolite membrane composite is the porous support-untreated zeolite membrane composite, the pretreatment step further includes a treatment step of converting the untreated zeolite membrane into a treated zeolite membrane.

According to one aspect of the present invention, the amount of water-soluble organic compounds permeated through the porous support-zeolite membrane composite can be evaluated in advance.

1 is a diagram schematically showing the configuration of an apparatus in which a porous support-untreated zeolite membrane composite in Example 1 was used in a pervaporation method. FIG. 3 is a diagram showing the relationship between the relative humidity of humidified air and the amount of air permeation in the porous support-untreated zeolite membrane composite in Example 1. This is a diagram showing the correlation between the amount of air permeation of conditioned air with a relative humidity of 8% in the porous support-untreated zeolite membrane composite in Example 1 and the amount of ethanol permeation due to pervaporation of a 95% ethanol aqueous solution. be. FIG. 3 is a diagram showing the correlation between the amount of air permeation of conditioned air with a relative humidity of 8% in the porous support-treated zeolite membrane composite in Example 2 and the amount of ethanol permeation due to pervaporation of a 95 volume % ethanol aqueous solution. . FIG. 2 is a diagram showing the amount of air permeation of conditioned air with a relative humidity of 8% through the porous support-treated zeolite membrane composite in Reference Example 1 and the amount of ethanol permeation due to pervaporation of a 95% by volume ethanol aqueous solution. FIG. 2 is a diagram showing the correlation between the amount of air permeation of conditioned air with a relative humidity of 8% in the porous support-treated zeolite membrane composite in Reference Example 2 and the amount of ethanol permeation due to pervaporation of a 95 volume % ethanol aqueous solution. .

An evaluation method according to an embodiment of the present invention evaluates the permeation amount of a water-soluble organic compound during pervaporation separation of a water-soluble organic compound aqueous solution having a specific water content concentration using a porous support-untreated zeolite membrane composite. It's a method. The evaluation method includes the following steps (1) to (3).
(1) Pretreatment step of conditioning the humidity of the zeolite membrane in the porous support-zeolite membrane composite.
(2) A step of measuring the amount of humidified air having a specific relative humidity permeating through the porous support-zeolite membrane composite.
(3) Based on the predetermined correlation between the permeation amount of humidified air having a specific relative humidity and the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution, A process of evaluating the amount of water-soluble organic compounds permeating through the zeolite membrane from the measured value of the permeation amount of humidified air.

In the embodiment of the present invention, the pretreatment step (1) is carried out as appropriate depending on the characteristics of the zeolite membrane. Embodiments of the present invention will be described below according to the characteristics of the zeolite membrane in the porous support-zeolite membrane composite.

[Embodiment 1: Evaluation of composite with untreated zeolite membrane]
When a porous support-untreated zeolite membrane composite is used for membrane separation in which water is separated from an aqueous solution of a water-soluble organic compound by permeation, the amount of permeation of the water-soluble organic compound may increase. The present inventors discovered this. In other words, membrane separation uses the molecular sieve effect of a zeolite separation membrane to separate components with relatively high permeability from a mixture of components with relatively high permeability and components with relatively low permeability. The present inventors have discovered that the amount of permeation of components with relatively low permeability decreases over time from the start of use, and sometimes becomes constant. Based on this knowledge, one of the challenges of the present inventors is to develop a technology that allows for prior evaluation of the ability to use a membrane separation technology using a porous support-untreated zeolite membrane composite.

The evaluation method according to the present embodiment evaluates the permeation amount of a water-soluble organic compound that permeates through a porous support-untreated zeolite membrane composite in pervaporative separation of a water-soluble organic compound aqueous solution having a specific water content concentration. .

[(1) Pretreatment step]
The evaluation method according to the present embodiment includes, as a pretreatment step, a treatment step in which an untreated zeolite membrane is converted into a treated zeolite membrane. In an embodiment of the present invention, a state in which water is adsorbed in the pores of the zeolite membrane is created by controlling the humidity of the zeolite membrane in the pretreatment step. Therefore, the pretreatment step can be carried out by various methods that allow water to contact the pores of the zeolite membrane. The humidity of the zeolite membrane can be controlled by leaving the porous support-zeolite membrane composite in an air atmosphere with a specific humidity, or by immersing the porous support-zeolite membrane composite in liquid water. It is possible to implement.

In this embodiment, the pretreatment step further includes a treatment step to convert the untreated zeolite membrane into a treated zeolite membrane. For example, when the porous support-untreated zeolite membrane composite contains silanol groups, the treatment step may be a method capable of dehydrating and condensing the silanol groups. Such a treatment step can be carried out by fully contacting the complex with ethanol at a sufficient concentration.

In this embodiment, the pretreatment step may be a step of simultaneously performing both the humidity conditioning of the untreated zeolite membrane and the treatment from the untreated zeolite membrane to the treated zeolite membrane. Such a pretreatment step is preferable from the viewpoint of simplifying the pretreatment step. From this point of view, the evaluation method of the present embodiment may include a step of pretreating the porous support-untreated zeolite membrane composite with an aqueous solution containing 95% by volume or more of ethanol.

Thus, in the pretreatment step, the porous support-untreated zeolite membrane composite may be pretreated with an aqueous solution containing 95% by volume or more of ethanol. Since the volume ratio may vary depending on the temperature, it is assumed to be the ratio at 20°C. The pretreatment only requires that the zeolite membrane comes into sufficient contact with the aqueous solution, for example, treatment of the liquid to be treated with a porous support-untreated zeolite membrane composite, except for using the above aqueous solution instead of the liquid to be treated. It can be carried out by applying the above aqueous solution to permeation through a zeolite membrane under the same conditions.

As mentioned above, the pretreatment step may be a step of converting an untreated zeolite membrane into a treated zeolite membrane. For example, if it is a step of promoting the dehydration condensation reaction of silanol groups, the pretreatment step may be a step of converting an untreated zeolite membrane into a treated zeolite membrane. It may be contact.

(Porous support - untreated zeolite membrane composite)
The porous support-untreated zeolite membrane composite used in this embodiment has a porous support and an untreated zeolite membrane. As the porous support, the porous support described in Patent Document 1 can be used. Preferably, the untreated zeolite membrane is formed on a porous support.

An untreated zeolite membrane is a zeolite membrane that has not undergone any treatment steps. The treatment step is a step in which, after the step, the amount of components that permeate through the zeolite membrane with relatively low permeability is reduced compared to before the step. Specifically, this is a step of performing one or more of heating, baking, surface treatment, and contact with a dehydration condensation reaction accelerator. Although the detailed mechanism is speculative, we believe that the reaction of the amorphous part contained in the untreated zeolite membrane reduces the amount of components with relatively low permeability that pass through the amorphous part.

Heating is a step in which the zeolite membrane is heated at a temperature that satisfies the conditions of the above-mentioned step. The heating temperature is 120°C or higher, preferably 150°C or higher, and more preferably 200°C or higher. From the viewpoint of preventing destruction due to the difference in coefficient of thermal expansion with the base material (support) of the separation membrane, the temperature is preferably 900°C or lower, more preferably 850°C or lower, and preferably 800°C or lower. The temperature is more preferably 750°C or lower, particularly preferably 500°C or lower, and most preferably 500°C or lower.

Calcination, when a zeolite membrane is synthesized using an organic templating agent, is removed by heating at a temperature such that the organic templating agent is thermally decomposed to a size that allows it to pass through the pores of the zeolite. The firing temperature is preferably 350°C or higher, more preferably 400°C or higher, even more preferably 430°C or higher, and even more preferably 450°C or higher, from the viewpoint of sufficiently removing the organic template agent. It is particularly preferable. From the viewpoint of preventing destruction due to the difference in coefficient of thermal expansion with the base material (support) of the separation membrane, the temperature is preferably 900°C or lower, more preferably 850°C or lower, and preferably 800°C or lower. The temperature is more preferably 750°C or lower, particularly preferably 500°C or lower, and most preferably 500°C or lower. The firing time is preferably 24 hours or more from the viewpoint of sufficiently removing the organic template agent, and preferably 72 hours or less from the viewpoint of productivity. Surface treatment is treatment with a compound such as a silane coupling agent.

Contact with a dehydration condensation reaction promoter is contact with a compound that promotes a dehydration condensation reaction of silanol groups. Examples of the dehydration condensation reaction accelerator include ethanol, carbon dioxide, and uric acid water. Ethanol may contain up to 10% by volume, preferably up to 5% by volume of water. The volume ratio here is the ratio at 20°C.

The temperature when ethanol is used as a dehydration condensation reaction accelerator can be appropriately determined within a range that allows sufficient treatment of the untreated zeolite membrane by contact. The temperature of ethanol used as a dehydration condensation reaction accelerator is preferably 25°C or higher, more preferably 50°C or higher, and 75°C or higher, from the viewpoint of shortening the treatment time of the untreated zeolite membrane in the contact step. The temperature is more preferably 90°C or higher, particularly preferably 100°C or higher, and most preferably 100°C or higher. Further, from the viewpoint of suppressing thermal decomposition of the untreated zeolite membrane, the temperature of the ethanol is preferably 135°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower. The above temperature range is the temperature under conditions of atmospheric pressure or higher.

In the case of contact with carbon dioxide, carbon dioxide may be a gas or may be in a supercritical state.

Examples of the contact method include a method in which a fluid containing the compound of the above example is permeated through the untreated zeolite membrane, and a method in which the untreated zeolite membrane is immersed or left in the fluid.

The untreated zeolite membrane may be a manufactured product or a commercially available product. An untreated zeolite membrane as a manufactured product is, for example, a zeolite membrane that has been synthesized without using an organic template that regulates the crystal structure of the zeolite and has not been calcined. Further, an untreated zeolite membrane as a manufactured product is a zeolite membrane that has not been subjected to a treatment step, which has been synthesized using an organic templating agent, and the organic templating agent has been removed by an oxidizing agent. The treatment conditions with the oxidizing agent are such that the dehydration condensation reaction of the silanol groups does not proceed completely. An untreated zeolite membrane can be manufactured by hydrothermal synthesis, and more specifically, for example, by the method described in Patent Document 1.

[(2) Measurement process]
The evaluation method according to the present embodiment includes the step of measuring the amount of humidified air having a specific relative humidity permeating the porous support-untreated zeolite membrane composite.

The conditioned air having a specific relative humidity need only have a relative humidity that has a sufficiently high correlation with the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution; It is determined as appropriate depending on the type of water-soluble organic compound in the aqueous organic compound solution and the specific water content concentration.

The amount of permeation of humidified air having a specific relative humidity is determined by the amount of permeation of a certain pressure between two spaces separated by the porous support and the untreated zeolite membrane composite in the porous support and the untreated zeolite membrane composite. It can be determined by forming a difference and measuring the flow rate in the relatively low-pressure space of air that has moved from the relatively high-pressure space to the relatively low-pressure space.

A porous support-untreated zeolite membrane composite produced by hydrothermal synthesis may allow a large amount of water-soluble organic compounds in an aqueous solution to permeate therethrough. Although the reason for this is not clear, it is thought that the untreated zeolite membrane in the porous support-untreated zeolite membrane composite produced by the above-mentioned hydrothermal synthesis contains amorphous sites. The reason why the amount of permeation of the above-mentioned water-soluble organic compound increases is considered to be that the amorphous site serves as a flow path for the organic compound.

The amorphous part is considered to be an aggregate of minute clay particles in which microscopic non-zeolite minerals, such as aluminosilicate minerals with low molecular weight such as feldspar, amorphous aluminum silicate, unreacted silicon source, and alumina source are aggregated with water. . The amorphous part contains uncondensed -OH groups, and is thought to expand and contract depending on the surrounding humidity and water content, as the osmotic pressure balance of water molecules impregnated in various parts of the amorphous part changes. . Therefore, when the water content in the water-soluble organic compound aqueous solution changes, it is predicted that the state of the amorphous site will change in response to the change. For this reason, simply measuring the amount of air permeation through a porous support-untreated zeolite membrane composite is not sufficient to measure the amount of permeation of a water-soluble organic compound during pervaporative separation of an aqueous solution of a water-soluble organic compound at a specific water content concentration. cannot be predicted.

Therefore, in addition to performing the above-mentioned pretreatment so that the amorphous part is in a state equivalent to the state of the amorphous part in pervaporation separation of an aqueous solution of a water-soluble organic compound with a specific water content concentration, the humidity conditioning is performed to bring the amorphous part into the state. It is necessary to specify the humidity of the air and perform the evaluation using conditioned air with the relevant humidity. The humidity is, for example, 5% or more and 80% or less in terms of relative humidity. Below this lower limit, the humidity is such that the molecular sieve of the zeolite begins to pass through air, and above this upper limit, even if there are gaps in the membrane, the pores (including the support) are sealed with water due to capillary condensation.

[(3) Evaluation process]
In the evaluation method according to the present embodiment, the amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution permeated through the porous support-untreated zeolite membrane composite is evaluated from the measured value of the permeation amount of the humidified air. The evaluation is performed based on a predetermined correlation between the permeation amount of humidified air having a specific humidity and the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution.

The amount of permeation of a water-soluble organic compound during pervaporation separation of a water-soluble organic compound aqueous solution is determined by accommodating the water-soluble organic compound aqueous solution in one side of the space separated by the porous support and untreated zeolite membrane composite, and storing the water-soluble organic compound aqueous solution in the other side. It is possible to determine the components contained in the water-soluble organic compound by creating a space and a pressure difference, and using the partial pressure difference of each component as a driving force to permeate the components contained in the water-soluble organic compound through the porous support-untreated zeolite membrane composite. .

An example of a combination of humidified air and a water-soluble organic compound aqueous solution that has a correlation in the amount of permeation through the porous support-untreated zeolite membrane composite is humidified air with a relative humidity of 8% and water content concentration of 5%. A combination with an aqueous ethanol solution of % by mass is included. Note that the combination of the relative humidity of the conditioned air and the water-soluble organic compound aqueous solution having a specific water content concentration is not limited to the above combination, but may be any combination that has the correlation described below.

The correlation serving as the evaluation standard is determined in advance for the permeation amount of humidified air having a specific humidity and the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution. The correlation will be explained below.

[Explanation about correlation]
The state of the untreated zeolite membrane when a water-soluble organic compound aqueous solution having a specific water content concentration permeates through pervaporation is substantially the same as that when humidified air having a specific humidity permeates through the untreated zeolite membrane. This is considered to be because the potential of water in the humidity-conditioned air and the potential of water in the aqueous solution of the water-soluble organic compound to be permeated and vaporized are substantially equal.

It is difficult to calculate the potential of water in an aqueous solution of a water-soluble organic compound that undergoes pervaporation. Therefore, by determining in advance the correlation between the permeation amount of humidified air through the porous support-untreated zeolite membrane composite and the permeation amount due to pervaporation of the water-soluble organic compound aqueous solution (for example, by creating a calibration curve), it is possible to From the amount of humidified air permeating through the porous support-untreated zeolite membrane composite, it is possible to estimate the amount of water-soluble organic compounds permeating through the porous support-untreated zeolite membrane composite due to pervaporation. . Hereinafter, a method for creating a calibration curve will be described as an example of how to determine the correlation.

[How to create a calibration curve]
The calibration curve is created by determining the humidity of the conditioned air used to predict the amount of permeation of water-soluble organic compounds, and then calculating the relationship between the estimated amount of permeation of the conditioned air at that humidity and the actually measured amount of permeation of water-soluble organic compounds. Create by asking. Specifically, a calibration curve is created in the following six steps.
(A) The permeation amount of humidity-controlled air in multiple patterns is measured for a sufficient number of porous support-untreated zeolite membrane composites.
(B) For each sample used in (A), find a relational expression between the humidity of the humidified air and the permeation amount of the humidified air.
(C) For the porous support-untreated zeolite membrane composite used in (A), measure the amount of permeation of the water-soluble organic compound during pervaporation separation of the aqueous solution of the water-soluble organic compound at a specific water content concentration.
(D) Using the results of (A) and (C), determine the humidity of the conditioned air so that the state is equivalent to the state of the amorphous part in pervaporative separation of a water-soluble organic compound aqueous solution with a specific water content concentration. demand.
(E) From the relational expression obtained in (B), calculate the amount of air permeation when using the humidity-controlled air with the humidity obtained in (D).
(F) For all the samples used in (A), calculate the relational expression between the permeation amount of the humidity-controlled air obtained in (D) and the permeation amount of water-soluble organic compounds obtained in (C). Calculate by the square method and use as a calibration curve.

In creating the calibration curve, it is assumed that the Hagen-Poiseuille law for continuous fluids can be applied to fluids that pass through leak paths other than the zeolite molecular sieve in pervaporation separation. That is, in this embodiment, the permeation amount of a water-soluble organic compound aqueous solution having a specific water content concentration in pervaporative separation by the porous support-untreated zeolite membrane composite and the It is assumed that the relationship with the permeation amount of humidified air follows the Hagen-Poiseuille law.

The Hagen-Poiseuille law regulates how a viscous liquid flows through a circular pipe with a constant diameter. The IPX8 waterproofing standard is used to estimate minute water leaks from air leaks.

Assuming that the leak path of the water-soluble organic compound aqueous solution in the untreated zeolite membrane is a straight pipe, in such a straight pipe model, the following formula (1) holds true according to the Hagen-Poiseuille law. The meanings of the letters in formula (1) are as follows.
Qa/Qw=(ηw/ηa)×(P1+P2)/(2×P2) (1)
Qa: Volumetric flow rate of humidified air at pressure P2 (mL/sec)
Qw: Volume flow rate of water-soluble organic compound aqueous solution at pressure P1 (mL/sec)
ηw: Viscosity coefficient of water-soluble organic compound aqueous solution (Pa・sec)
ηa: Viscosity coefficient of humidified air (Pa・sec)
P1: Primary side pressure (e.g. atmospheric pressure) (Pa abs)
P2: Pressure on the secondary side (e.g. negative pressure) (Pa abs)
R: radius of pipe (cm)

In this way, when the leak path is approximated as a straight pipe, there is a correlation in which the ratio of the flow rate of the humidified air to the flow rate of the water-soluble organic compound aqueous solution is constant according to the Hagen-Poiseuille law. However, in the separation of aqueous solutions of water-soluble organic compounds in porous support-untreated zeolite membrane composites, the composition changes during pervaporation. For this reason, it is difficult to determine the viscosity of an aqueous solution of a water-soluble organic compound. Therefore, for the porous support-untreated zeolite membrane composite, the amount of permeation during pervaporation of an aqueous solution of a water-soluble organic compound is measured a sufficient number of times, and the correlation with the amount of permeation of conditioned air having a specific relative humidity is determined. .

The method for creating a calibration curve will be explained in more detail.
First, a sufficient number of porous support-untreated zeolite membrane composites are prepared. Next, for each porous support-untreated zeolite membrane composite, the amount of air permeation of conditioned air having a specific relative humidity (for example, multiple conditions such as 1%, 5%, 8%, 10%, etc.) is measured. do. Next, for each porous support-untreated zeolite membrane composite, a relational expression (an approximate expression of an exponential function, see FIG. 2) between the permeation amount of humidified air having a specific relative humidity and the relative humidity is determined.

Here, the amount of permeation of humidified air through the untreated zeolite membrane can be approximated to an exponential function of the relative humidity of the humidified air. The reason for this is not clear, but it is thought to be because the horizontal axis is relative humidity, an index directly connected to the chemical potential of water molecules, which simplifies the correlation between the amount of permeation in humidified air and relative humidity.

Next, using the relative humidity of the humidified air as a variable, determine the equilibrium water vapor pressure (same or almost equal to the saturated water vapor equilibrium water vapor pressure) at which the relative humidity allows the zeolite crystal to adsorb water vapor to such an extent that gases smaller than the molecular sieve can be ignored within the error range. to the water vapor pressure at which capillary condensation occurs.

Using the relational expression determined for each porous support-untreated zeolite membrane composite, the permeation amount of humidified air at a specific humidity is calculated for each porous support-untreated zeolite membrane composite. Separately, for each porous support-untreated zeolite membrane composite, the amount of water-soluble organic compound permeated in the pervaporative separation of a water-soluble organic compound aqueous solution with a specific water content concentration (for example, 5% by mass) (in formula (1) Qa) is measured.

The amount of permeation of the humidified air calculated for the above-mentioned fully porous support-untreated zeolite membrane composite and the amount of permeation of the actually measured water-soluble organic compound are linearly approximated, and the correlation coefficient of the linear approximation formula is calculated. demand. Here, the humidity of the conditioned air with the maximum correlation coefficient is determined, and the humidity of the conditioned air is used to predict the permeation amount of the water-soluble organic compound in pervaporative separation of the aqueous solution of the water-soluble organic compound with a specific water content concentration. shall be. Here, the reason why the calculated permeation amount of humidified air and the actually measured permeation amount of water-soluble organic compounds are linearly approximated is because it is assumed that the Hagen-Poiseuille law can be applied, as described above.

The amount of permeation of the conditioned air when using the conditioned air with the determined humidity was calculated using the approximate formula obtained for each porous support-untreated zeolite membrane composite, and the amount of the actually measured water-soluble organic compound was calculated. The relational expression with the amount of transmission is calculated using the least squares method. This relational expression is used as a calibration curve (see FIG. 3).

In one aspect of the present invention, by using the calibration curve obtained in this way, if the permeation amount of conditioned air having a specific relative humidity is measured through the porous support-untreated zeolite membrane composite, the It is possible to estimate the permeation amount of a water-soluble organic compound during pervaporative separation of an aqueous organic compound solution with a specific water content concentration through an untreated zeolite membrane. Therefore, it is possible to evaluate the amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution permeating through the porous support-untreated zeolite membrane composite from the measured value of the permeation amount of the humidified air.

Therefore, according to one aspect of the present invention, by a simple operation of permeating the prepared porous support-untreated zeolite membrane composite with humidified air having a specific relative humidity and determining the amount of permeation. , pervaporative separation of a water-soluble organic compound aqueous solution using a porous support-untreated zeolite membrane composite without performing a complicated separation operation to determine the permeation amount of a water-soluble organic compound in the pervaporative separation of a water-soluble organic compound aqueous solution. It is possible to predict the permeation amount of water-soluble organic compounds. Furthermore, the untreated zeolite membrane is evaluated as described above using humidified air at room temperature and pressure. Therefore, it is possible to suppress the occurrence of accidents or failures during the evaluation, shorten the inspection procedure and time, and save labor.

[Embodiment 2: Evaluation of composite with treated zeolite membrane]
The evaluation method according to the present invention is also applicable to the above-mentioned composite having a treated zeolite membrane. This embodiment differs from the first embodiment described above in the pretreatment step. That is, in this embodiment, a porous support-treated zeolite membrane composite is used instead of a porous support-untreated zeolite membrane composite.

[(1) Pretreatment step]
In this embodiment, the pretreatment step may be a step of controlling the humidity of the treated zeolite membrane. For example, the pretreatment step can be a step of exposing the porous support-treated zeolite membrane composite to humidified air under pressurized conditions. In this embodiment, the step of exposing to humidified air is preferable from the viewpoint that air having a specific relative humidity determined by temperature and pressure can be easily prepared. The end point of the pretreatment step can be determined by confirming that water adsorption of the porous support-treated zeolite membrane composite under the conditions of the pretreatment step has substantially ceased. The pretreatment may be performed in a closed space with controlled humidity, indoors, or in a module equipped with a separation membrane.

(Porous support-treated zeolite membrane composite)
The porous support-treated zeolite membrane composite used in this embodiment has a porous support and a treated zeolite membrane. The porous support may be the same as in Embodiment 1 described above.

A treated zeolite membrane is a zeolite membrane that has been subjected to some kind of treatment during the manufacturing process that can turn an amorphous untreated part of the zeolite membrane into a treated part. The treated zeolite membrane is a zeolite membrane in which the state of adsorption sites of the zeolite membrane is substantially fixed to the state at the time of pervaporative separation of a water-soluble organic compound aqueous solution. The "treatment" referred to here can also be referred to as a treatment to fix the state of the adsorption sites of the zeolite membrane, which may be unstable during the manufacturing process, to the state at the time of pervaporation separation, for example, by performing the above-mentioned calcination. The process is applicable.

The porous support-treated zeolite membrane composite may be a manufactured product or a commercially available product. The processed zeolite membrane of the composite as a manufactured product is, for example, a zeolite membrane that has been synthesized using an organic templating agent and calcined. Such a treated zeolite membrane can be manufactured by hydrothermal synthesis, and more specifically, for example, by the method described in Patent Document 2 or a method similar thereto.

[(2) Measurement process and (3) Evaluation process]
The measurement process and the evaluation process in the evaluation method according to the present embodiment can be performed in the same manner as in the first embodiment described above, except for the air permeation method.

In an embodiment of the present invention, the amount of air permeation may be measured by an appropriate method depending on the properties of the porous support-zeolite membrane composite. When the humidity-controlled air is permeated through the treated zeolite membrane, in this embodiment, as in Embodiment 1, a specific pressure difference is formed between the two spaces separated by the porous support-treated zeolite membrane composite, It can be determined by measuring the flow rate in the relatively low-pressure space of air that has moved from the relatively high-pressure space to the relatively low-pressure space.

In Embodiment 1, it is preferable to create a relative pressure difference by applying negative pressure to the inside of the composite; however, in this embodiment, to create a relative pressure difference by applying negative pressure to the outside of the composite. This method is suitable from the viewpoint of stably and accurately determining the permeation amount of humidity-controlled air. In this embodiment, the same applies to the measurement of the amount of permeation of a water-soluble organic compound in pervaporation separation of an aqueous solution of a water-soluble organic compound, and it is preferable to form a relative pressure difference with the outside of the composite body as a positive pressure. .

[Modified example]
In an embodiment of the present invention, the pretreatment step may be a step of bringing the humidified air in the measurement step into sufficient contact with the porous support-zeolite membrane composite. In this case, the pretreatment step is a step of bringing humidity-controlled air into contact with the porous support-zeolite membrane composite immediately before the start of the measurement step.

In the embodiment of the present invention, as shown in the reference examples described below, if the preprocessing step is insufficient, the correlation used in the evaluation step may become low, resulting in a decrease in the accuracy of the evaluation results. . However, the end point of the pretreatment step can also be determined as appropriate depending on the desired accuracy of the evaluation results. From this point of view, in the embodiments of the present invention, the preprocessing step may be appropriately simplified from the content of the above description depending on the desired precision.

〔summary〕
As is clear from the above explanation, the evaluation method according to the first aspect of the present invention is applicable to the pervaporative separation of a water-soluble organic compound aqueous solution having a specific water content concentration using a porous support-zeolite membrane composite. This method includes the following steps (1) to (3).
(Step 1) Pretreatment step of conditioning the humidity of the zeolite membrane in the porous support-zeolite membrane composite.
(Step 2) Step of measuring the amount of humidified air having a specific relative humidity permeating the porous support-zeolite membrane composite.
(Step 3) Based on the predetermined correlation between the permeation amount of humidified air having a specific relative humidity and the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution, A process of evaluating the amount of water-soluble organic compounds that permeate through the zeolite membrane from the measured value of the permeation amount of humidified air.
When the porous support-zeolite membrane composite is a porous support-untreated zeolite membrane composite, the pretreatment step further includes a treatment step of converting the untreated zeolite membrane into a treated zeolite membrane.
Therefore, according to the evaluation method, it is possible to evaluate in advance the amount of water-soluble organic compounds that permeate through the porous support-zeolite membrane composite.

In a second aspect of the present invention, in the first aspect, the porous support-zeolite membrane composite is a porous support-untreated zeolite membrane composite, and the pretreatment step is a porous support-untreated zeolite membrane composite. It may be a step of pre-treating the treated zeolite membrane composite with an aqueous solution containing 95% by volume or more of ethanol. This configuration is even more effective in terms of early stabilization of the porous support-untreated zeolite membrane composite.

A third aspect of the present invention is that in the first aspect or the second aspect, the porous support-untreated zeolite membrane composite is synthesized without using an organic templating agent that regulates the crystal structure of the zeolite; In addition, the zeolite membrane may be an uncalcined zeolite membrane. In this configuration, since water-soluble organic compounds are likely to leak from the untreated zeolite membrane, it is highly effective to evaluate the amount of leakage in advance, and it is even more effective.

A fourth aspect of the present invention is that in the first aspect, the porous support-zeolite membrane composite includes a porous support and a treated zeolite membrane, and the treated zeolite membrane has an organic template that regulates the crystal structure of the zeolite. It may also be a zeolite membrane synthesized using a chemical agent and calcined. This configuration is highly effective in enabling preliminary evaluation of various characteristically treated zeolite membranes, and is even more effective.

In a fifth aspect of the present invention, in any of the first to fourth aspects, the relative humidity of the humidity-controlled air may be 5% or more and 80% or less. This configuration is even more effective from the viewpoint of increasing the accuracy of evaluating the permeation amount of a water-soluble organic compound in pervaporative separation of a water-soluble organic compound aqueous solution having a specific water content concentration.

In a sixth aspect of the present invention, in any one of the first to fifth aspects, the water content concentration of the water-soluble organic compound aqueous solution may be 5% by volume. This configuration is even more effective from the viewpoint of increasing the correlation between the amount of permeation of the humidified air and the amount of permeation of the water-soluble organic compound due to pervaporation of the aqueous solution of the water-soluble organic compound.

In a seventh aspect of the present invention, in any of the first to sixth aspects, the water-soluble organic compound may be ethanol, and the humidity-controlled air may be air with a relative humidity of 8%. This configuration is even more effective from the viewpoint of increasing the correlation between the amount of permeation of the humidified air and the amount of permeation of the water-soluble organic compound aqueous solution due to pervaporation.

In one aspect of the present invention, the amount of permeation of a water-soluble organic compound in an aqueous solution of a water-soluble organic compound through a porous support-untreated zeolite membrane composite is evaluated by a much simpler operation than direct measurement. Is possible. Therefore, one embodiment of the present invention is expected to contribute to the spread and development of technology using zeolite membranes, and to contribute to the achievement of Sustainable Development Goals (SDGs) related to industry and technological innovation.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

An embodiment of the present invention will be described below. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist thereof.

[Example 1]
In the following Examples, the particle size distribution of seed crystals, air permeation amount, and pervaporation performance were measured by the methods described below.

[Measurement of particle size distribution]
The particle size distribution of the seed crystals used to generate the untreated zeolite membrane was measured under the following conditions.
・Device name: Laser diffraction particle size distribution measuring device LA-500 (manufactured by Horiba, Ltd.)
・Measurement method: Combination of Franhofer diffraction theory and Mie scattering theory ・Measurement range: 0.1 to 200 μm
・Light source: He-Ne laser (632.8nm)
・Detector: Ring-shaped silicon photodiode ・Dispersion solvent: Water

The dispersion liquid used to measure the particle size distribution of seed crystals is prepared by placing water in the ultrasonic dispersion bath of the measuring device and circulating the dispersion liquid through a flow cell while stirring with a stirrer, and measuring the intensity of light transmitted through the dispersion liquid. It was prepared by adding seed crystals to water in an ultrasonic dispersion bath to fall within the proper light intensity range displayed on the instrument. The amount of water used as a dispersion solvent at this time is usually 250 mL, and if the seed crystals to be dispersed are powder, the amount is usually 0.01 g. When powdered seed crystals were added, ultrasonic waves were applied for 5 minutes to remove aggregation of the seed crystals in the dispersion, and then measurement was performed using a flow method.

[Air permeation amount measurement]
One end of the cylindrical porous support-zeolite membrane composite, in which an untreated zeolite membrane is supported on the surface of the porous support, is sealed, and the other end is heated to 50 Torr (6.67 kPa) in a sealed state. Connected to a vacuum line with a pressure of 710 Torr (94.7 kPa) (atmospheric pressure outside), the air flow rate was measured with a mass flow meter installed between the vacuum line and the porous support-zeolite membrane composite. The air permeation amount of the treated zeolite membrane was defined as [L/(m ² ·h)]. As a mass flow meter, 8300 manufactured by KOFLOC, for N ₂ gas, with a maximum flow rate of 500 mL/min (20° C., converted to 1 atmosphere) was used. If the mass flow meter reading of the KOFLOC 8300 is 10 mL/min (20°C, 1 atm) or less, use LINTEC's 3102L-NN-4swLAA00, for _N2 gas, maximum flow rate 200ml/min (25°C, 1 atm). The amount of air permeation was measured using 1 atm (converted to 1 atm).

[Humidity control air permeation measurement]
For measuring the amount of permeation of humidified air, air conditioned at 25°C was used, kofloc 3810DSII (1000 sccmFS) was used to measure the mass flow rate of the permeated air, and the pressure difference was set to 0.5 kPa. The permeation amount of humidified air was measured in the same manner as the measurement of the air permeation amount, except that it was measured using sensor AP-48 and normalized to the flow rate per unit differential pressure. Relative humidity was measured using a SENSIRION SHT31 temperature and humidity sensor.

[Pervaporation performance measurement]
Performance measurement by pervaporation method using porous support-zeolite membrane composite was performed by selecting water from a 100°C water/ethanol aqueous solution (5/95% by mass) as the liquid to be treated under the following conditions. This was done by permeation separation.

A schematic diagram of the apparatus used for the pervaporation method is shown in FIG. As shown in FIG. 1, the device is connected to a raw material tank 1 containing an aqueous organic compound solution as a raw material, a membrane module 2 containing a porous support-zeolite membrane composite, and a membrane module 2 connected to the raw material tank 1 containing an aqueous organic compound solution as a raw material. It has a vacuum pump 3. A measuring trap 4 is connected between the membrane module 2 and the vacuum pump 3.

The membrane module 2 includes a metal cylindrical body, a connecting member connected to one end of the cylindrical body (on the measurement trap 4 side), and a closing member that seals the other end of the cylindrical body in an openable/closable manner. There is. The membrane module 2 contains a porous support-untreated zeolite membrane composite. One end of the porous support-untreated zeolite membrane composite is connected to a connecting member, and the space on the inner peripheral side of the porous support-untreated zeolite membrane composite is connected to the porous support-untreated zeolite membrane. It is cut off from the space on the outer circumferential side of the composite, and communicates with the measurement trap 4 via a connecting member. The other end of the porous support-untreated zeolite membrane composite is sealed.

The raw material tank 1 is configured to be able to supply raw materials to the membrane module 2 via a supply tank 5 and a heater 6. Further, the raw material in the membrane module 2 is configured so that it can be returned to the supply tank 5 or to the raw material tank 1 via the cooler 7. Moreover, the raw material can be circulated between the supply tank 5 and the heater 6. Furthermore, it is configured so that the raw material returned from the cooler 7 to the raw material tank 1 can be sampled. Pumps P1, P2 and valves V1 to V12 are appropriately arranged in the flow path of the device.

The space on the inner peripheral side of the porous support-untreated zeolite membrane composite in the membrane module 2 is depressurized by the vacuum pump 3, and the porous support-untreated zeolite membrane composite is in contact with the organic compound aqueous solution. The pressure difference with the space on the outer circumferential side of the body is 330 kPa. Due to this pressure difference, water as a permeable substance in the organic compound aqueous solution permeates into the porous support-untreated zeolite membrane composite toward the inner circumferential space of the porous support-untreated zeolite membrane composite. It vaporizes and passes through. The permeated substance (water) is collected by the measuring trap 4. On the other hand, the organic compound in the organic compound aqueous solution remains outside the porous support-untreated zeolite membrane composite in the membrane module 2.

The operating time of the above device in pervaporation performance measurement is 60 minutes, and the flow rate of the permeate collected in the measurement trap 4 during 45 to 60 minutes and the weight Qa of ethanol in the permeate are determined as Qa ₆₀ . ,evaluated.

[Example of production of porous support-untreated zeolite membrane composite]
An aqueous reaction mixture for hydrothermal synthesis was prepared as follows. 37.6 g of aluminum hydroxide (containing 53.5 wt% Al ₂ O ₃ , manufactured by Aldrich), 243.0 g of a 25 wt% KOH aqueous solution, and 1910.2 g of water were mixed and stirred to dissolve and form a solution. 232.5 g of colloidal silica (Snowtech-40, manufactured by Nissan Chemical Industries, Ltd.) was added to this and stirred for 2 hours to form an aqueous reaction mixture. The composition (molar ratio) of this aqueous reaction mixture was SiO ₂ /Al ₂ O ₃ /KOH/H ₂ O = 1/0.125/0.7/80, SiO ₂ /Al ₂ O ₃ = 8. .

A porous alumina tube (outer diameter 12 mm, inner diameter 9 mm, length 1200 mm) was washed with an ultrasonic cleaner and dried to obtain an inorganic porous support as a support for a zeolite membrane.

Mix 5.00 g of NaOH and 100 g of water with 10.0 g of proton type FAU zeolite (manufactured by Catalysts & Chemicals Co., Ltd., trade name HY (SAR=5)), heat at 100°C for 7 days, filter, wash with water, and dry. As a result, crystals of FAU type zeolite were obtained. When the volume-based particle size distribution of the crystals of this FAU type zeolite was measured, the D50 was 1.73 μm, and the maximum values were 1.32 μm and 2.98 μm.

The above FAU type zeolite crystals are used as seed crystals, the seed crystals are dispersed in water at 2% by mass, the above support is immersed in this dispersion for a predetermined period of time, and then dried at 100°C for 5 hours or more. A seed crystal was attached to the. The mass of the attached seed crystal was 3 g/m ² .

The support to which the seed crystals were attached was inserted into a PFA inner cylinder (1400 mm), and the above aqueous reaction mixture was added to the support so that it was higher than the height of the support. The inner cylinder was inserted into an autoclave, the autoclave was sealed, and the temperature was raised from room temperature to 180°C over 5 hours. After completion of temperature rise, hydrothermal synthesis was performed by heating at 180° C. for 24 hours under autogenous pressure in a stationary state. Immediately after heating is completed, the porous support/zeolite membrane composite is allowed to cool, and the porous support/zeolite membrane composite is removed from the aqueous reaction mixture. After washing, the zeolite membrane composite is inserted into an autoclave, and the demineralized water is heated to a level higher than the height of the zeolite membrane composite. I added it so that it would be. The autoclave was sealed and heated under autogenous pressure at 120° C. for 20 hours to perform hot water washing. Thereafter, it was air-dried at room temperature. In this way, a porous support-zeolite membrane composite was obtained in which an untreated CHA type zeolite membrane was supported on the outer peripheral surface of the porous support.

[Creating a calibration curve]
Porous support-untreated zeolite membrane composites were synthesized in batches of 36 pieces each according to the Preparation Example. The obtained porous support-untreated zeolite membrane composite was divided into three sets of 12 pieces each, each set was placed in a stainless steel sealed container, and the whole was immersed in a 95% by volume ethanol aqueous solution. After replacing the air in the space above the airtight container, the air in the porous material, and the air dissolved in the ethanol with nitrogen, the pressure was reduced using a diaphragm pump, and the airtight container was sealed and heated at 100°C for 2 hours. Holds time. After cooling to 50° C., the porous support-untreated zeolite membrane composite was taken out, washed with water, and pretreated by air drying at room temperature for 24 hours.

For each of the composites (samples), the amount of permeation of humidified air was measured, and then the permeation and vaporization performance described above was measured.

In the humidity control air permeation amount measurement, the air permeation amount of each sample was measured at relative humidity of 1.80%, 2.79%, 4.85%, 7.94% and 8.97%. FIG. 2 shows the relationship between the relative humidity of the humidified air and the permeation amount of the humidified air in each sample. As shown in FIG. 2, it can be seen that the relative humidity of the humidity-conditioned air and the amount of humidity-conditioned air permeation have an exponential relationship. Furthermore, Qa ₆₀ was measured for each sample.

For all samples, exponential approximation was performed separately using Microsoft Excel (registered trademark) to obtain the values of b and m in the following formula (1).
y=b×m ^ax formula (1)
In the above formula (1),
y: Air permeation amount (mL/m ² )
x: relative humidity (%)
a: coefficient 1
b: coefficient 2
m: bottom

Note that "a" in the coefficient 1 represents the rate of increase in leakage per humidity, and is an index regarding the microscopic structure of the zeolite in the zeolite membrane. "a" can be an index of, for example, the density of the amorphous within the zeolite membrane or the degree of development of the network due to the crystal structure of the zeolite in the zeolite membrane. "b" of coefficient 2 represents the ultimate leakage amount at zero humidity and is an index of the absolute leakage amount. "b" can be an index of the amorphous amount if the quality of the amorphous in the zeolite membrane is the same.

Subsequently, a graph was created with the predicted air permeation amount _yp as the horizontal axis and the actual measured value of Qa ₆₀ as the vertical axis. With relative humidity x as a variable, relative humidity x _n being 0% or more as a constraint condition, the relative humidity x _hmax that maximizes the coefficient of determination R ² of the straight line obtained from Qa ₆₀ and y _p by the least squares method. was calculated using Microsoft Excel (registered trademark) solver. A straight line representing the correlation when the relative humidity x _hmax (x _hmax = 8.0 under the conditions described in the example) was obtained was used as a calibration curve. The obtained calibration curve is shown in FIG.

A porous support-untreated zeolite membrane composite obtained by the same method as in the above production example was placed in a stainless steel sealed container, and the whole was immersed in a 95% by volume ethanol aqueous solution. After replacing the air in the space above the airtight container, the air in the porous material, and the air dissolved in the ethanol with nitrogen, the pressure was reduced using a diaphragm pump, and the airtight container was sealed and heated at 100°C for 2 hours. Holds time. After cooling to 50° C., the porous support-untreated zeolite membrane composite was taken out, washed with water, and pretreated by air drying at room temperature for 24 hours. The composite was pretreated by drying by leaving it at room temperature for half a day before measurement, and the composite was used as a measurement sample.

A metal cylindrical connecting member was attached to one end of the pretreated porous support-untreated zeolite membrane composite, and a metal closing member was attached to the other end.

Subsequently, the amount of humidity-controlled air permeation was measured using conditioned air at 25° C. and 8% relative humidity. The result was 55 sccm/line (1160 mm)/0.1 MPa.

Qa ₆₀ was determined from the permeation amount of the obtained humidified air using a calibration curve prepared in advance and shown in FIG. 3, and was found to be 208 (kg/(m ² ·h)).

Separation in which water is selectively permeated from a water/ethanol aqueous solution (5/95% by mass) at 100°C by the pervaporation method using the porous support-untreated zeolite membrane composite used in this example. I did it. As a result, the ethanol Qa ₆₀ of the porous support-untreated zeolite membrane composite after 60 minutes was 82 (kg/(m ² ·h)). This value was within the 99.7% by mass prediction interval derived from the sample for which the above calibration curve was created.

As shown in this example, it can be seen that by using the method of the present invention, it is possible to accurately predict Qa by a simple humidity control air permeation measurement without performing a complicated permeation vaporization performance measurement. In addition, the air permeation rate of the porous support-zeolite membrane composite with no physical damage obtained in the above production example is <1 sccm/piece (1160 mm)/0.1 MPa regardless of Qa, which is just It can be seen that Qa cannot be calculated accurately from the air permeation measurement.

Note that the upper limit of the prediction interval of 99.7% by mass (3σ) for a component with relatively low permeability (ethanol) is shown by a broken line in FIG. By adding the low-risk element of humidity adjustment to the easy and low-risk method of air permeation measurement, the amount of permeation of components with relatively low permeability through the separation membrane during separation of aqueous solutions of water-soluble organic compounds increases. It can be seen that it is possible to construct a linear correlation in a complex system of phenomena in which there is. It can be seen that the present invention, which utilizes such a correlation, is very useful in, for example, product development or inspection processes.

[Example 2]
A specific example of the method for evaluating a porous support-treated zeolite membrane composite will be described below.

<Production example of porous support-treated zeolite membrane composite>
A porous alumina tube (outer diameter 12 mm, inner diameter 9 mm, average pore diameter 1.45 μm) was used as the porous support. As a zeolite seed crystal, SiO ₂ /Al ₂ O ₃ /NaOH/KOH/H ₂ O/N,N,N-trimethyl-1-adamantanammonium hydroxide (TMADAOH) = 1.00/0.0165/0.120 A CHA type zeolite seed crystal obtained by crystallizing a gel composition of /0.0550/19.897/0.07 at 160° C. for 2 days by hydrothermal synthesis was used. The average particle diameter of the zeolite seed crystals was 0.98 μm.

The porous support was immersed for 1 second in a dispersion of zeolite seed crystals dispersed in water at 0.1% by mass, and then dried at 120°C for 2 hours or more to support the zeolite seed crystals on the porous support. I let it happen. When the mass of the porous support before and after the support was measured, the amount of zeolite seed crystals supported was 0.7 g/m ² .

A 25% KOH aqueous solution and a 1N-NaOH aqueous solution were added to the demineralized water, and aluminum hydroxide (containing 54% by mass of Al ₂ O ₃ , manufactured by Kyowa Kagaku Co., Ltd.) was added and dissolved to form a transparent solution. Furthermore, a TMADAOH aqueous solution (containing 20% by mass of TMADAOH, manufactured by Seichem) was added as an organic template, and then colloidal silica (Snowtex ST-S, manufactured by Nissan Chemical Co., Ltd.) was added and stirred for 120 minutes or more to obtain an aqueous reaction mixture. The composition (mole ratio) of this aqueous reaction mixture is SiO ₂ /Al ₂ O ₃ /NaOH/KOH/H ₂ O/TMADAOH=1.0/0.064/0.075/0.15/100/0. 044, SiO ₂ /Al ₂ O ₃ =15.7.

The support to which the seed crystals were attached was immersed vertically into a reaction vessel containing the above aqueous reaction mixture, the reaction vessel was sealed, and the support was heated under autogenous pressure at 180°C for 18 hours in a standing state. . At this time, the ratio of the aqueous reaction mixture to the support was about 2050 g of the aqueous reaction mixture per m of the support, so that the entire support was in contact with the aqueous reaction mixture. After a predetermined period of time had elapsed, the zeolite membrane composite was allowed to cool, taken out from the aqueous reaction mixture, washed, and dried at 120° C. for 2 hours or more.

The membrane composite was fired at 500° C. for 10 hours in an electric furnace to remove the organic template remaining in the porous support, thereby obtaining the porous support-zeolite membrane composite of Example 1. The temperature increase rate and temperature decrease rate during firing were both 0.5° C./min. In the manner described above, a porous support-treated zeolite membrane composite in which a CHA type zeolite membrane was supported on the outer peripheral surface of the porous support was obtained.

<Creating a calibration curve>
Porous support-treated zeolite membrane composites were synthesized in batches of 36 pieces each according to the above production example. Thirty-one pieces of the obtained porous support-treated zeolite membrane composite were attached to a jig for installation in a stainless steel airtight container, and kept in an air atmosphere at 22°C and 70% relative humidity for 5 hours or more. . In this way, the pretreatment step of the porous support-treated zeolite membrane composite was carried out.

Humidity-adjusted air permeation amount was measured for each of the composites (samples). To measure the amount of humidity-adjusted air permeation through the porous support-treated zeolite membrane composite, the membrane installed in a jig is placed in a stainless steel sealed container, and 0.00% is measured from the outside of the porous support-treated zeolite membrane composite. Humidity-controlled air pressurized to 3 MPa was supplied, and the amount of air that passed through each membrane was measured.

Then, as in Example 1, a graph is created in which the horizontal axis is the measured air permeation amount y _p and the vertical axis is the actual measured value of Qa ₃₀ , and the minimum value representing the correlation between the air permeation amount and the Qa ₃₀ at that time is A straight line determined by the square method was used as a calibration curve. The obtained calibration curve is shown in FIG.

In addition, Qa of IPA of the porous support-untreated zeolite membrane composite after 30 minutes when separation was performed to selectively permeate water from a water/IPA aqueous solution (5/95% by mass) at 100°C. was set as Qa ₃₀ , and the Qw of water was set as Qw ₃₀ .

<Evaluation of porous support-treated zeolite membrane composite>
Among the porous support-treated zeolite membrane composites prepared in the production example of the porous support-treated zeolite membrane composite in Example 2, one that had not been evaluated by the pervaporation method was prepared, and one end of the composite was prepared. After attaching a metal cylindrical connecting member to the other end and attaching a metal closing member to the other end, the pretreatment process of this example was performed. Next, the amount of permeation of humidified air at 22° C. and 0.3 MPa was measured, and the predicted value of Qa ₃₀ was determined from the amount of permeation of humidified air using the calibration curve shown in FIG. 4 created in advance. It was 0.013 (kg/(m ² ·h)).

The porous support-treated zeolite membrane composite evaluated in this way was actually used in the pervaporation method to selectively permeate water from a water/IPA aqueous solution (5/95% by mass) at 100°C. went. As a result, the IPA Qa ₃₀ of the porous support-untreated zeolite membrane composite after 30 minutes was 0.014 (kg/(m ² ·h)). This was a value within the 95% by mass prediction interval derived from the sample for which the above calibration curve was created.

[Reference example 1]
For the porous support-treated zeolite membrane composite whose Qa ₃₀ and Qw ₃₀ were known after evaluation by the pervaporation method, the pretreatment step of Example 2 was extended to 8 hours and a humidity conditioning step was performed. The amount of air permeation was determined. Further, the amount of air permeation was determined in the same manner as in Example 2 except that the pretreatment step was not performed. The results are shown in Figure 5. In FIG. 5, the black circles represent the former 8-hour humidity control, and the black triangles represent the latter no pretreatment. From FIG. 5, it was found that the straight line determined by the least squares method obtained from each result passes near the origin in the 8-hour humidity control treatment, but does not pass through the origin without pretreatment. This indicates that without pretreatment, the zeolite pores are not sufficiently filled with water, and air passes through the zeolite pores in the air permeation measurement. If the humidity control during pretreatment was insufficient, the degree to which the pores in the zeolite crystals would be filled with water would vary each time the test was conducted, and it could not be said that the evaluation was performed under constant conditions, so pretreatment was performed. It can be said that it is preferable.

[Reference example 2]
Similarly, a porous support-treated zeolite membrane composite with known Qa ₃₀ and Qw ₃₀ was subjected to the pretreatment step of Example 2 for 8 hours to perform a humidity conditioning step to reduce the amount of air permeation. I asked for it. Further, the amount of air permeation was determined in the same manner as in Example 2 except that the holding time in the air atmosphere of 22° C., 0.3 MPa, and 70% relative humidity in the pretreatment step was changed to 3 hours. The results are shown in FIG. In FIG. 6, the black triangles represent the former 8-hour humidity control, and the black circles represent the latter 3-hour humidity control. From FIG. 6, it was found that the straight line determined by the least squares method obtained from each result passes near the origin in the 8-hour humidity control process, but does not pass through the origin in the 3-hour humidity control process. This indicates that the zeolite pores were not sufficiently filled with water after 3 hours of humidity conditioning, and that air passed through the zeolite pores in the air permeation amount measurement. If the pretreatment humidity control is insufficient, the degree to which the pores in the zeolite crystals will be filled with water will vary each time the test is performed, and it cannot be said that the evaluation is being performed under constant conditions. It can be said that it is preferable to carry out treatment.

INDUSTRIAL APPLICATION This invention can be utilized for simple and highly accurate prediction and evaluation of the permeation amount of a component with relatively low permeability in an object to be separated in an untreated zeolite membrane.

1 Raw material tank 2 Membrane module 3 Vacuum pump 4 Measurement trap 5 Supply tank 6 Heater 7 Cooler P1, P2 Pump V1 to V12 Valve

Claims (7)

A method for evaluating the permeation amount of a water-soluble organic compound in pervaporative separation of a water-soluble organic compound aqueous solution having a specific water content concentration using a porous support-zeolite membrane composite, the method comprising:
(1) a pretreatment step of conditioning the humidity of the zeolite membrane in the porous support-zeolite membrane composite;
(2) measuring the amount of humidified air having a specific relative humidity permeating through the porous support-zeolite membrane composite; and (3) measuring the amount of humidified air having the specific relative humidity permeating and the The amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution that permeates through the zeolite membrane is determined based on a predetermined correlation with the permeation amount of the water-soluble organic compound in the water-soluble organic compound aqueous solution. A process of evaluating from the measured value of the amount of permeation of humid air,
including;
In the case where the porous support-zeolite membrane composite is a porous support-untreated zeolite membrane composite, the pretreatment step further includes a treatment step of converting the untreated zeolite membrane into a treated zeolite membrane. Method. The porous support-zeolite membrane composite is the porous support-untreated zeolite membrane composite, and the pretreatment step includes the porous support-untreated zeolite membrane composite containing 95% by volume or more of the porous support-untreated zeolite membrane composite. The method according to claim 1, wherein the step is pretreatment with an aqueous solution containing ethanol. The porous support-untreated zeolite membrane composite includes a porous support and an untreated zeolite membrane, the untreated zeolite membrane is synthesized without an organic templating agent that regulates the crystal structure of the zeolite, and 2. The method of claim 1, wherein the zeolite membrane is an uncalcined zeolite membrane. The porous support-zeolite membrane composite includes a porous support and a treated zeolite membrane, the treated zeolite membrane being a zeolite synthesized using an organic templating agent that regulates the crystal structure of the zeolite and calcined. 2. The method of claim 1, wherein the method is a membrane. The method according to claim 1, wherein the humidity-controlled air is air with a relative humidity of 5% or more and 80% or less. The method according to claim 1, wherein the water concentration is 5% by volume. 7. The method of claim 6, wherein the water-soluble organic compound is ethanol and the conditioned air is air with a relative humidity of 8%.

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