Method for drying a separation membrane

Abstract

Drying method for a separation membrane (12), comprising: supplying a gas for drying to the separation membrane (12) for a predetermined time such that the flow rate distribution of the gas for drying on the membrane surface of the separation membrane (12) is less than or equal to 15%;wherein the flow rate distribution is calculated as a flow rate of the gas for drying near the membrane surface at all membrane surface positions of the separation membrane (12) on the side supplied with the gas for drying in a configuration in which there is the same pressure on a first main surface side (S1) and a second main surface side (S2) of the separation membrane (12), and is calculated as a value obtained by dividing the difference between the maximum value of the membrane surface flow rate and the minimum value of the membrane surface flow rate by the minimum value of the membrane surface flow rate, the gas for drying has a temperature of less than or equal to 40°C and contains a water-soluble gas having a solubility in 1 cm3 of water of more than or equal to 0.5 cm3 under conditions of 40°C and 1 atmosphere, and the average pore diameter of the separation membrane (12) is 0.0002 µm to 1.0 µm.

Description

TECHNICAL AREA

[0001] The present invention relates to a method for drying a separation membrane and a method for producing a separation membrane structure. TECHNICAL BACKGROUND

[0002] Separation membranes are traditionally used in many sectors, such as the chemical, electronics, and pharmaceutical industries. A gas separation membrane typically incorporates a zeolite membrane, a silicon dioxide membrane, a carbon membrane, a polymer membrane, or similar materials, depending on the size of the gas molecules to be separated.

[0003] Because the pores of this type of separation membrane are fine, they tend to become blocked by water adsorbed during installation in a housing or from the air during storage. Since gas permeation is inhibited and sufficient membrane performance cannot be achieved when a pore is blocked, it is necessary to dry the separation membrane after installation.

[0004] Known examples of a drying process for a separation membrane include a process for heating the housing of the separation membrane (reference to patent literature 1), a process for supplying heated gas to the separation membrane (reference to patent literature 2), and a process for drying the separation membrane after wetting it with a mixed low-alcohol solution (reference to patent literature 3). A further drying process is known in which gas is supplied to a plurality of tubular separation membranes (reference to patent literature 4). List of citations from patent literature [Patent Literature 1] Japanese Patent Application Disclosure No. 2012-246207 [Patent Literature 2] Japanese Patent Application Disclosure No. 2016-104486 [Patent Literature 3] Japanese Patent Application Disclosure No. 60-216811 [Patent Literature 4] Japanese Patent Application Disclosure No. 2016-159211 BRIEF DESCRIPTION OF THE INVENTION Technical Problem

[0005] However, the method disclosed in patent literature 1 and 2 requires a device for heating the housing or the gas, and the method disclosed in patent literature 3 requires a device for supplying the mixed low-alcohol solution. Furthermore, patent literature 4 does not consider which gases have properties adapted to drying the separation membrane, nor the fact that the gas flow on the membrane surface is uneven and that time is required to complete the drying process, since the method disclosed in patent literature 4 uses baffle plates.

[0006] The present invention is proposed taking into account the circumstances described above, and the purpose of providing a drying process enables a simple and rapid drying of a separation membrane and a method for producing a separation membrane structure that uses this drying process. Solution to the problem

[0007] The drying process for a separation membrane according to the present invention comprises the step of supplying a drying gas to the separation membrane such that a value obtained by dividing the difference between the maximum and minimum flow rates of the drying gas on a membrane surface of the separation membrane by the minimum flow rate is less than or equal to 15%. The drying gas is at a temperature of less than or equal to 40°C and contains a water-soluble gas that is present in 1 cm³. 3 Water has a solubility of more than or equal to 0.5 cm 3 exhibits under conditions of 40°C and 1 atmosphere. Effect of the invention

[0008] The present invention enables the provision of a drying process that allows for simple and rapid drying of a separation membrane, and a process for manufacturing a separation membrane structure that uses this drying process. List of characters Fig. Figure 1 is a sectional view illustrating a separation membrane module according to one aspect. Fig. Figure 2 is a schematic representation of the evaporation of water through a drying treatment. Fig. Figure 3 is a sectional view illustrating another separation membrane module. Fig. Figure 4 is a schematic representation illustrating another drying process. DESCRIPTION OF THE VERSIONS Configuration of the separation membrane module 100

[0009] Fig. 1 is a sectional view showing a separation membrane module 100 represents the module 100includes a separation membrane structure 1 , a case 2 and an O-ring 3 .

[0010] The separation membrane structure 1 It has a monolithic configuration. A monolithic configuration refers to a form in which a large number of cells are arranged longitudinally, resembling a honeycomb. Besides a monolithic form, the shape of the separating membrane structure is also important. 1 Whether the membrane can be tubular, cylindrical, columnar, prismatic, a flat plate or the like, a monolithic shape is suitable because it can increase the membrane surface area per unit volume or reduce the flow rate distribution.

[0011] The separation membrane structure 1 is inside the case 2 arranged. The housing 2 is equipped with an inlet passage 21 , a first recovery round 22 and a second recovery cycle 23equipped. Both end sections of the separation membrane structure 1 are through the O-rings 3 sealed.

[0012] The separation membrane structure 1 includes a porous support 11 and a separating membrane12. Porous support 11

[0013] The porous carrier 11 It has a monolithic form that extends longitudinally. Inside the porous support. 11 A large number of cells are formed. CL Each cell CL extends lengthwise. Each cell CL It is formed in a cylindrical shape. Each cell CL is connected to both end faces of the porous support 11 tied together.

[0014] The porous carrier 11It consists of a binder and an aggregate. The aggregate includes the use of aluminum oxide, silicon carbide, titanium oxide, mullite, clay shards, and cordierite, or the like. The binder includes the use of at least one alkali metal and one alkaline earth metal, and a glass material containing aluminum (Al) and silicon (Si). The binder content in the substrate 11 can be greater than or equal to 20 vol% and less than or equal to 40 vol%, and can preferably be greater than or equal to 25 vol% and less than or equal to 35 vol%.

[0015] Although, for example, there is no particular limitation regarding the porosity of the porous substrate 11 It can be configured as 25% to 50%. The porosity of the porous substrate 11 can be measured by mercury intrusion porosimetry. Although there is no particular limitation regarding the average pore diameter of the porous support. 11If available, it can be adjusted from 0.1 µm to 50 µm. Depending on the pore diameter, the average pore diameter of the porous substrate can be determined. 11 by mercury intrusion porosimetry, a test developed in ASTM F316 described airflow method or measured by permerometry. Separating membrane 12

[0016] The separating membrane 12 is applied to the inner surface of each cell CL formed. The separating membrane 12 It is shaped in a cylindrical form. The separating membrane 12 enables the permeation of a permeation component contained in the mixed fluid.

[0017] The separating membrane 12includes a zeolite membrane (e.g., reference to Japanese Patent Application Disclosure No. 2004-66188), a silicon dioxide membrane (e.g., reference to the PCT Disclosure Brochure Application 2008 / 050812), a carbon membrane (e.g., reference to Japanese Patent Application Disclosure 2003-286018), an organic-inorganic hybrid membrane (e.g., reference to Japanese Patent Application Disclosure 2013-203618), and a ceramic membrane (e.g., reference to Japanese Patent Application Disclosure 2008-246304), or the like.

[0018] The average pore diameter of the separation membrane 12The filtration efficiency can be determined according to the required filtration and separation efficiency and configured, for example, as 0.0002 µm - 1.0 µm. The drying method of the present application is superior when drying a separation membrane having an average pore diameter of less than or equal to 10 nm and is particularly useful when drying a separation membrane having an average pore diameter of less than or equal to 1 nm.

[0019] A suitable method for measuring the average pore diameter of the separation membrane 12 can be selected in response to the size of the pore diameter. For example, if the separation membrane 12In the case of a zeolite membrane, the average pore diameter is taken as the arithmetic mean of the major diameter and the minor diameter of n-membered oxygen ring pores with a framework forming the pores of the zeolite, consisting of rings of less than or equal to a value n of the n-membered oxygen ring. The n-membered oxygen ring has a number n of oxygen atoms that configure the pore-forming framework, includes at least one of a Si atom, Al atom, or P atom, and is part of a ring structure in which the respective oxygen atoms are bonded to a Si atom, an Al atom, a P atom, or the like. If the zeolite has a large number of n-membered oxygen ring pores in which n takes on the same value, the average pore diameter of the zeolite is considered to be the arithmetic mean of the main diameter and the smaller diameter of all n-membered oxygen ring pores.In this way, the average pore diameter of a zeolite membrane can be clearly determined with reference to the International Zeolite Association (IZA) “Database of Zeolite Structures” [online], [accessed on November 21, 2014], Internet<URL: http: / / www.iza-structure.org / databases / > The published values ​​are calculated.

[0020] If the separating membrane 12 For a silicon dioxide membrane, a carbide membrane, or an organic-inorganic hybrid membrane, the average pore diameter can be calculated based on the following formula (1). In formula (1), d p the average pore diameter, f denotes the normalized Knudsen permeance, d k,i denotes the diameter of the molecule used in the Knudsen diffusion test, and d k,He denotes the diameter of a helium molecule. f = ( 1 − d k ,i / d p ) 3 / ( 1 − d k ,He / d p ) 3 The details of the calculation method for the average pore diameter or Knudsen diffusion test are disclosed in Hye Ryeon Lee (et al., (four others)), “Evaluation and fabrication of pore-size-tuned silica membranes with tetraethoxydimethyl disiloxane for gas separation”, AIChE Journal, Volume 57, Issue 10, 2755-2765, October 2011.

[0021] If the separating membrane 12 For example, if it is a ceramic membrane, the average pore diameter can be calculated using permporometry or nanoperm porometry, depending on the size of the pore diameter. Method for producing the separation membrane structure 1

[0022] An example of a method for producing a separation membrane structure 1 is described. Production of porous support 11

[0023] First, a clay is produced by adding water, a dispersion agent and an organic binder, such as methylcellulose, to form an aggregate and a binder, and then kneaded.

[0024] The green body for the porous support 11 The produced clay is formed in a slip casting mold, a press mold or an extrusion mold using a vacuum extruder.

[0025] Then the green body is used for the porous support. 11 fired (e.g., 500°C to 1500°C, 0.5 hours to 80 hours) to create a porous substrate 11 with a multitude of cells CL to form. Production of the separation membrane 12

[0026] On an inner surface of each cell CL of the porous substrate 11 A separating membrane is used. 12 formed. The formation of the separating membrane 12may involve the use of a method that is tailored to the membrane type of the separation membrane 12 is adapted. Assembly and drying of the separation membrane 12

[0027] The O-rings 3 are located at both end sections of the porous support 11 including the separating membrane 12 They are attached and located in an inner section of the housing. 2 included.

[0028] At this point, the pores tend to become blocked by water in the air, which is drawn from the pores of the separating membrane. 12 It is adsorbed. If a pore is blocked, sufficient membrane performance cannot be demonstrated, and it is necessary to replace the separation membrane. 12 The drying process must be carried out after assembly. Therefore, in the present embodiment, the following drying treatment is performed.

[0029] In particular, when supplying an inner section of the housing 2with a gas for drying from the inlet passage 21 the gas used for drying, which has passed along the respective dry gas flow path, from the first recovery pass 22 obtained and that the separation membrane 12 Penetrating gas for drying from the second recovery pass 23 obtained. In the present embodiment, the supply of gas for drying is carried out continuously or intermittently. The amount of gas used for drying can be reduced by intermittently supplying the gas for drying.

[0030] In this step, the gas is passed through the separation membrane for a predetermined time to dry. 12 supplied so that the flow rate distribution of the gas for drying on the membrane surface of the separation membrane 12less than or equal to 15%. The flow rate distribution is calculated as a flow rate of the gas for drying near the membrane surface (approximately 1 to 2 mm from the membrane surface) at all membrane surface positions of the separation membrane. 12 on the side supplied with the gas for drying in a configuration in which an equal pressure is applied to a first main surface S1 -page (referring to Fig. 2, not shown in Fig. 1) and a second main area S2 -page (referring to Fig. 2, not shown in Fig. 1) consists of the separating membrane 12and is calculated as a value obtained by dividing the difference between the maximum value of the membrane surface flow rate and the minimum value of the membrane surface flow rate by the minimum value of the membrane surface flow rate ([maximum flow rate - minimum flow rate] / minimum flow rate). The pressure on the first main surface S1 -side and the second main area S2 -side of the separating membrane 12 can be achieved by sealing the second recovery passage 23 The flow rate of the gas passing through the membrane must be balanced. If the membrane surface flow rate varies over time, e.g., with intermittent gas supply for drying, an average value for the membrane surface flow rate during the gas supply for drying is considered the value for the membrane surface flow rate.

[0031] The entire separation membrane 12The same quantity can be dried by adjusting the flow rate distribution to less than or equal to 15%. Therefore, the separation membrane 12 through a configuration that increases the difference in drying rate across the entire separation membrane 12 Reduced, efficient drying in a short time. The flow rate distribution is preferably less than or equal to 10%. It should be noted that if difficulties arise in measuring the actual membrane surface flow rate, the flow rate distribution can be measured using a flow simulation.

[0032] A flow rate distribution of less than or equal to 15% is preferably achieved by arranging the separation membrane 12 achieved, so that the gas is essentially parallel to the membrane surface of the separation membrane for drying. 12flows, and by substantially compensating the shape of a dry gas flow path in a cross-section that is perpendicular to the direction of gas flow for drying at any section of the membrane surface.

[0033] The dry gas flow path is a chamber through which the gas flows for drying. The dry gas flow path serves to make contact with the separation membrane. 12 In the present embodiment, the dry gas flow path is a space on the inside of the separating membrane. 12 In Fig. 1. The direction of flow of the gas for drying, which flows in the dry gas flow path, is called F d designated. In the Fig. The example shown in 1 is the shape of the dry gas flow path in a cross-section that is orthogonal to the flow direction. F d The gas flows in a circle to dry, which has the same approximate size along the entire flow direction.

[0034] Furthermore, as in Fig. As shown in 1, for a multitude of dry gas flow paths, it is preferred that the mean value of the shortest distance between adjacent dry gas flow paths in a cross-section that is orthogonal to the flow direction is F d The diameter of the gas being dried is less than or equal to 5 mm. In this way, it is possible to further reduce the flow rate distribution in each drying gas flow path.

[0035] In the present embodiment, the water-soluble gas is a gas that has a solubility in 1 cm. 3 Water level of more than or equal to 0.5 cm 3under conditions of 40°C and 1 atmosphere. This type of water-soluble gas includes CO2, acetylene, and H2S, or similar substances. However, CO2 is particularly preferred, primarily due to its safety and ease of procurement. Although there is no specific limitation regarding the inclusion of a gas other than a water-soluble one (a water-insoluble gas) in the drying process, dry air, nitrogen, or argon are suitable due to their ease of acquisition and low cost.

[0036] One type, two types, or more types of a water-soluble gas can be incorporated into the gas for drying. In addition, one type, two types, or more types of a water-insoluble gas can be incorporated into the gas for drying.

[0037] Although a water-soluble gas can be included in the drying gas, the rate of the drying treatment can be increased by increasing the proportion of the water-soluble gas. More precisely, the proportion of the water-soluble gas is preferably greater than or equal to 10 mol%, more preferably greater than or equal to 20 mol%, and even more preferably greater than or equal to 50 mol%. The drying gas can essentially consist only of the water-soluble gas. It is noted that if two or more types of water-soluble gases are included in the drying gas, the sum of the proportions of each water-soluble gas is considered to be the total proportion of the water-soluble gas.

[0038] The kinetic diameter of at least one type of water-soluble gas molecules in the drying gas is preferably less than or equal to the average pore diameter of the separation membrane. 12In this way, it is possible to efficiently effect the permeation of the water-soluble gas as described below. The value for the kinetic diameter of the water-soluble gas molecule is given in D.W. Breck, "Zeolite Molecular Sieves: Structure, Chemistry and Use", John Wiley & Sons, New York, 1974, p. 636.

[0039] The temperature of the gas used for drying can be less than or equal to 40°C. If the gas used for drying is less than or equal to 40°C, this means that no active heat treatment has been performed on the gas used for drying. Therefore, as a result, it is not necessary to provide a heating system in addition to the drying system for the separation membrane. Since the gas used for drying is less than or equal to 40°C, the amount of water dissolved in the water can also be increased, as described below. Although there is no particular lower limit for the temperature of the gas used for drying, a value greater than or equal to -20°C is preferred, greater than or equal to 0°C is more preferred, and greater than or equal to 10°C is particularly preferred in order to increase the rate of the drying process.

[0040] The drying gas preferably contains no water. In particular, the water content ratio in the drying gas is preferably less than or equal to 2 g / m³. 3 , preferably less than or equal to 0.1 g / m³ 3 and especially preferred to be less than or equal to 0.03 g / m³ 3 .

[0041] The specified time (i.e., the drying time) for supplying the gas for drying is set according to the type of water-soluble gas, the content ratio of the water-soluble gas in the gas for drying, and the temperature of the gas for drying, or similar factors.

[0042] The pressure of the drying gas at the start of drying (i.e., the time for the start of the gas supply for drying) is preferably higher than the drying gas pressure at the end of drying (i.e., when the gas supply for drying is continuously applied to the separation membrane). 12 is stopped, or immediately before the gas supply for drying is restarted after the gas supply for drying has ended in the case of discontinuous gas supply to the separation membrane. 12 ). Since in this way the drying of the separation membrane 12Since the associated gas flow rate for drying can be reduced by lowering the pressure of the gas after the drying treatment is complete, unnecessary gas usage for drying can be avoided. It should be noted that with intermittent gas supply to the separation membrane for drying... 12 The pressure of the gas used for drying after completion of the drying treatment in each feed cycle may be lower than the pressure at the beginning of the drying process.

[0043] In this context Fig. 2 A schematic view illustrating the evaporation of water through a drying treatment. Fig. 2 is a representation of a configuration where the pores 12a the separating membrane 12 are blocked by water.

[0044] As in Fig. As shown in 2, the gas is used to dry the first main surface. S1 the separating membrane 12supplied. The water-soluble gas contained in the drying gas dissolves in the pores. 12a rises in the water and penetrates the second main surface S2 -page one. At this point, the water that enters the pores 12a blocked, as water vapor evaporates. In addition, a water-soluble gas and a water-insoluble gas contained in the drying gas can pass through these pores to the second main surface. S2 -side if there are pores that are not blocked by water in the separation membrane 12 are blocked or if there are pores from which water escapes, which is blocking the pores of the separating membrane 12 The blockage was removed by drying. The permeation gas is understood to be the combination of the water-soluble gas and the water-insoluble gas that, due to the two aforementioned configurations, reaches the second main surface. S2 -page reached. The permeation gas is from the second recovery cycle. 23recovered after it, together with the water vapor evaporated from the water, which fills the pores 12a blocked by the porous substrate 11 has passed through it.

[0045] Gas for drying, which crosses the separation membrane 12 which has not penetrated, makes contact with the water and then passes through the cells. CL together with the water vapor evaporated from the water. The water vapor and the gas for drying, which the cells CL What happened will be from the first recovery round 22 won.

[0046] The drying method according to the present embodiment enables quick and easy drying of the separation membrane. 12 and avoids heat treatment at temperatures above 40°C, as the effect of water evaporation, which fills the pores, is detrimental. 12a both from the first main surface S1 -side as well as from the second main interface S2-side blocked by the permeation of a water-soluble gas through the pores blocked by water 12a is intensified.

[0047] The partial pressure of the water-soluble gas on the first main surface S1 -side (hereinafter referred to as "first partial pressure"), which is supplied with the gas for drying in the drying process according to the present embodiment, is preferably higher than the partial pressure of the water-soluble gas on the second main surface. S2 -side (hereinafter referred to as "second partial pressure"). In this way, the drying rate of the separation membrane is controlled. 12 further increased, as the water-soluble gas is efficiently dissolved in the water that fills the pores. 12a blocked.

[0048] The first partial pressure is preferably greater than or equal to 20 kPa higher than the second partial pressure. The pressure difference between the first and second partial pressures can be adjusted by changing the pressure on the drying gas entering from the feed point. 21 The pressure can be easily controlled. Furthermore, the pressure difference between the first partial pressure and the second partial pressure can be reduced by creating a vacuum on the second primary surface. S2 -side by creating suction from the second recovery pass 23 controlled using a vacuum pump.

[0049] With the completion of the aforementioned drying treatment, the separation membrane structure 1 completed. OTHER VERSIONS

[0050] Although one embodiment of the present invention has been described, the present invention is not limited to the foregoing embodiment, and various modifications are possible to an extent that does not deviate from the inventive concept.

[0051] In the present embodiment, a configuration has been described in which the drying process according to the present invention is applied to a monolithic separation membrane structure. 1 The drying method according to the present invention can be applied to a separation membrane structure with various shapes, such as tubular, cylindrical, circular columnar, prism, flat plate, or the like. Fig. Figure 3 is, for example, an illustration of a configuration in which the drying process according to the present invention is applied to a flat plate-shaped separation membrane structure. 1'is applied. However, if the shape of the separation membrane structure is not monolithic (e.g., tubular or the one in Fig. 3 or similar flat plate configurations), difficulties arise in reducing the flow rate distribution, as it is difficult to compensate for the flow path shape when the separating membrane structure is actually mounted on a housing.

[0052] In the present embodiment, the gas was indeed applied to the first main surface for drying. S1 the separating membrane 12 delivered, however, there is no limit in this regard. As in Fig. As shown in 4, for example, the gas can be used to dry the second main surface S2 the separating membrane 12 be supplied. That is, the gas for drying can be supplied by the porous substrate. 11 -page about the separation membrane 12 will be delivered. In this configuration, as in Fig. 4 shown, the housing2 an inlet passage 21' added and the inlet passage 21 can be closed. The water-soluble gas contained in the drying gas, which comes from the inlet passage, 21' is delivered by the cells CL from a second recovery cycle 23' after water has passed through the pores 12a the separating membrane 12 blocked, recovered. The remaining gas for drying is taken from a first recovery pass. 22' won. It's like in Fig. 4 shown, but preferably when the gas is used for drying in a substantially vertical configuration relative to the membrane surface of the separation membrane 12 is introduced because it is difficult to reduce the flow rate distribution, as in Fig.As shown in Figure 1, it is preferred to reduce the flow rate distribution by introducing the gas for drying in a substantially parallel position to the membrane surface of the separation membrane.

[0053] Although the gas is continuously applied to the separation membrane for drying 12 In the present embodiment, the gas can be intermittently applied to the separation membrane for drying. 12 be delivered. More precisely, a cycle can be repeated in which, after the gas has been used to dry an inner section of the casing, an inner section can be dried. 2 has filled the inlet passage 21 and the first recovery cycle 22 to be closed, penetrating gases and water vapor from the second recovery cycle 23 be recovered and then the gas is used for drying in the housing 2is replaced. In this configuration, the amount of gas used for drying, which is used in the drying treatment of the separation membrane, can be adjusted. 12 The amount used can be reduced. In addition, the recovered gas can be used for drying and the permeation gas can be dehumidified and reused.

[0054] In the present embodiment, although the separating membrane 12 directly onto the porous substrate 11 was formed, one or more intermediate layers between the separating membrane 12 and the porous substrate 11 The intermediate layers can be arranged with the same material as the porous supports. 11 The pore diameter of the intermediate layers is preferably smaller than the pore diameter of the porous substrate. 11 . Examples Samples No. 1 to 5

[0055] First, 30 vol% of an inorganic binder was added to 70 vol% aluminum oxide particles (aggregate) with an average particle diameter of 12 µm. Then, a further shaping aid, such as an organic binder or the like, and a pore-forming agent were added. The mixture was dry-mixed, a surfactant and water were added, and the mixture was blended and kneaded to produce clay. The inorganic binder was mixed with talc, kaolin, feldspar, clay, or the like, with an average particle diameter of 1 to 5 µm, to form a composition of SiO₂ (70 wt%), Al₂O₃ (16 wt%), alkaline earth metals, and alkali metals ( 11 Mass%) was used.

[0056] The clay was then extruded to produce a green body for a monolithic porous support. This green body was then fired (1250°C, one hour) to create a multi-celled aluminum oxide base material.

[0057] Subsequently, PVA (an organic binder) was added to an aluminum oxide powder to create a slurry. This slurry was then used to form a green body for the interlayer on an inner surface of the cells of the aluminum oxide base material. The green body was then fired (1250°C, 1 hour) to form the interlayer.

[0058] Subsequently, both end faces of the aluminum oxide base material were sealed with glass. In this way, a monolithic porous substrate was created.

[0059] Subsequently, a separation membrane was formed according to the method disclosed in International Publication WO2011105511, in which a DDR-type zeolite membrane (average pore diameter: 4.0 nm) was formed on an intermediate layer of an inner surface of each cell of a porous support. The DDR-type zeolite membrane was exposed to water vapor for one minute to regenerate a configuration in which water in the air was absorbed by the DDR-type zeolite membrane.

[0060] Subsequently, in samples No. 1 to No. 4, a porous support formed from a zeolite membrane of the GDR type was placed in a housing, as described in Fig. 1 shown, and in sample no. 5 a porous support formed from a zeolite membrane of the GDR type was placed in a housing as shown in Fig. 4 shown.

[0061] Subsequently, a drying treatment was performed on the DDR-type zeolite membrane, using a gas flow for drying. The drying conditions are shown in Table 1. In samples 1 and 5, CO2, a water-soluble gas, was used as the drying gas, while in samples 2 to 4, He, N2, and Ar, which are water-insoluble gases, were used. The temperature of the drying gas was normalized to 27°C (room temperature). Furthermore, in sample 1, the pressure differential between the permeation side and the supply side of the drying gas (water-soluble gas) was measured in three patterns: 10 kPa, 20 kPa, and 100 kPa. In samples 2 to 5, the pressure differential between the permeation side and the supply side of the drying gas (water-insoluble gas) was set to 100 kPa. Additionally, in sample 1, the pressure differential between the permeation side and the supply side of the drying gas (water-insoluble gas) was measured in three patterns: 10 kPa, 20 kPa, and 100 kPa.Two patterns were performed by varying the shape of the supply path to obtain a flow rate distribution of 10% and 15% at a pressure difference of 100 kPa. Since a single-component gas was used as the drying gas in this example, the pressure difference between the permeation side and the supply side was equal to the partial pressure difference of the water-soluble gas or the water-insoluble gas. Furthermore, in the samples... 1 until 4 confirmed that the size of the flow rate distribution was less than or equal to 15%, while in sample No. 5 the size of the flow rate distribution was greater than 15%.

[0062] The flow rate of each gas was considered to be 100% when the flow rate of the gas permeating the DDR-type zeolite membrane became constant, and the drying time was defined as the time from when the drying gas stream began until the flow rate of each gas permeating the DDR-type zeolite membrane reached 95%. The drying time for each sample is summarized in Table 1. It should be noted that the flow rate of the gases permeating the DDR-type zeolite membrane was measured using a gas flow meter. Table 1 Sample No. Drying conditions Drying time until gas permeation minimum quantity 95% (min) Flow rate distribution (%) Gas for drying Feed side pressure (kPa) Permeation side pressure (kPa) Partial pressure difference (kPa) Gas type Solubility in 1 cm 3 Water at 40°C and 1 atmosphere (cm²) 3 ) Kinetic diameter (nm) 1 10 CO2 0,53 0,33 201 101 100 5 15 201 101 100 7 15 121 101 20 14 15 111 101 10 18 2 15 He 0,0084 0,26 201 101 100 24 3 15 N2 0,012 0,36 201 101 100 30 4 15 Ar 0,027 0,34 201 101 100 31 5 31 CO2 0,53 0,33 201 101 100 20

[0063] As shown in Table 1, based on a comparison of the drying time when the flow rate distribution was set and the partial pressure difference was set at 100 kPa, sample No. 1, in which a water-soluble gas (CO2) with a solubility in 1 cm³ 3 Water level of more than or equal to 0.5 cm3 Under conditions of 40°C and 1 atmosphere, the drying time was reduced compared to samples No. 2 to No. 4, which used a water-insoluble gas. This result is due to the fact that water, which blocked the pores of the DDR-type zeolite membrane, could be evaporated from both surfaces of the DDR-type zeolite membrane.

[0064] Furthermore, based on a comparison of drying times when the partial pressure difference was set at 100 kPa, sample No. 1, in which the flow rate distribution was less than or equal to 15%, showed a reduction in drying time compared to sample No. 5, in which the flow rate distribution was greater than 15%. It was also confirmed that a flow rate distribution of less than or equal to 10% in sample No. 1 enabled drying within 5 minutes at a gas permeation rate greater than or equal to 95%. This result is attributed to the fact that efficient drying of the entire membrane was achieved by drying the entire DDR-type zeolite membrane at essentially the same rate.

[0065] Furthermore, based on a comparison of the drying time when the flow rate distribution was set and the partial pressure difference was varied at 100 kPa, it was confirmed in sample No. 1 that drying was activated within 15 minutes at a gas permeation quantity of more than or equal to 95% when the partial pressure difference was greater than or equal to 20 kPa.

[0066] Furthermore, the fact that the drying time in sample No. 2 was shorter than in samples No. 3 and No. 4 is considered to be due to the smaller kinetic diameter of He compared to that of N₂ or Ar; He tends to penetrate pores more easily than N₂ or Ar. However, since the drying time in sample No. 1, which used CO₂, which has a larger kinetic diameter than He, could be reduced, it was confirmed that solubility in water had a greater influence on the drying time than the kinetic diameter. It is clear that the same reduction in drying time was achieved in sample No. 1, as the same effect was obtained from a configuration using a different water-soluble gas than CO₂, since the drying time is strongly influenced by solubility in water.

[0067] Since the drying time was shortened by the permeation of a water-soluble gas through water, which clogs the pores, it is clear that the drying time could be shortened by using a drying gas containing two or more water-soluble gases. Furthermore, even when using a drying gas containing two or more water-soluble gases, it is clear that the drying time was shortened because the partial pressure of the water-soluble gas on the supply side was higher than the partial pressure of the water-soluble gas on the permeation side.

[0068] Although the present example used a separation membrane configured as a DDR-type zeolite membrane, the drying method used with respect to sample No. 1 is also effective with respect to a separation membrane made of a material that tends to absorb water into its pores. In particular, the drying method used with respect to sample No. 1 is effective with respect to a separation membrane made of a material where the pore diameter is less than or equal to 10 nm. Reference symbol list 1 Separating membrane structure 11 POROUS SUPPORTS 12 Separating membrane 2 HOUSINGS 21 Inlet Passage 22 FIRST RECOVERY ROUND 23 SECOND RECOVERY CL CELL QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2012246207

[0004] JP 2016104486

[0004] JP 60216811

[0004] JP 2016159211

[0004] JP 200466188

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[0017] WO 2011105511

[0059] Cited non-patent literature

[0000] Hye Ryeon Lee (et. al., (four others)), “Evaluation and fabrication of pore-size-tuned silica membranes with tetraethoxydimethyl disiloxane for gas separation”, AIChE Journal, Volume 57, Issue 10, 2755-2765, October 2011

[0020] D. W. Breck, „Zeolite Molecular Sieves: Structure, Chemistry and Use“, John Wiley & Sons, New York, 1974, S. 636

[0038]

Claims

[1] Drying process for a separation membrane, comprising: Supplying a gas for drying to the separation membrane such that a value obtained by dividing the difference between a maximum and a minimum flow rate of the gas for drying on a membrane surface of the separation membrane by the minimum flow rate is less than or equal to 15%; and wherein the gas for drying is less than or equal to 40°C and contains a water-soluble gas having a solubility in 1 cm 3 Water level of more than or equal to 0.5 cm 3 exhibits under conditions of 40°C and 1 atmosphere. [2] Drying method for a separation membrane according to claim 1, wherein a first partial pressure of the water-soluble gas on a first main surface side of the separation membrane, which is supplied with the gas for drying, is higher than a second partial pressure of the water-soluble gas on a second main surface side of the separation membrane. [3] Drying method for a separation membrane according to claim 2, wherein the first partial pressure is greater than or equal to 20 kPa higher than the second partial pressure. [4] Drying method for a separation membrane according to any one of claims 1 to 3, wherein at least a part of the water-soluble gas is carbon dioxide. [5] Drying method for a separation membrane according to any one of claims 1 to 4, wherein the gas for drying contains more than or equal to 10 mol% of the water-soluble gas. [6] Drying method for a separation membrane according to any one of claims 1 to 5, wherein the separation membrane is formed on an inner surface of a cell of a monolithic porous support. [7] Drying method for a separation membrane according to any one of claims 1 to 6, wherein the separation membrane and a dry gas flow path are arranged such that the gas for drying is introduced essentially parallel to the membrane surface of the separation membrane, and a form of the dry gas flow path on a cross-section that is perpendicular to a flow direction of the gas to dry, which is essentially the same at any section of the membrane surface. [8] Drying method for a separation membrane according to any one of claims 1 to 7, wherein a large number of dry gas flow paths are provided, and an average of the shortest distance between the multitude of dry gas flow paths is less than or equal to 5 mm. [9] Drying method for a separation membrane according to any one of claims 1 to 8, wherein the pressure of the gas for drying at the beginning of a drying treatment is higher than the pressure of the gas for drying after completion of a drying treatment. [10] Drying method for a separation membrane according to any one of claims 1 to 9, wherein the gas is supplied intermittently for drying the separation membrane. [11] Method for producing a separation membrane structure, comprising: Assembly of a porous support on which a separating membrane is formed into a housing, and Supplying a drying gas at a temperature of less than or equal to 40°C to the separation membrane, wherein the drying gas contains a water-soluble gas having a solubility in 1 cm 3 Water greater than or equal to 0.5 cm 3 exhibits under conditions of 40°C and 1 atmosphere. [12] Method for producing a separation membrane structure according to claim 11, wherein the gas for drying contains more than or equal to 10 mol% of the water-soluble gas.