Apparatus and method for producing gel

Abstract

The purpose of the present invention is to provide a gel production apparatus and gel production method capable of industrially producing a homogeneous gel. A gel production apparatus (1) comprises a sol production unit (10), a gel production unit (40), a sol supply pipe (20) that supplies sol produced by the sol production unit (10) to the gel production unit (40), and a temperature control unit (30) that controls the temperature of the sol flowing through the sol supply pipe (20). The sol production unit (10) produces sol having a temperature T1 from a mixture containing a silica precursor, a catalyst, and a macropore-forming agent. The gel production unit (40) produces a gel by controlling the temperature of the sol supplied by the sol supply pipe (20) to be a gelation temperature T2. The temperature control unit (30) controls the temperature of the sol flowing through the sol supply pipe (20) to be a temperature T3 that is higher than the temperature T1 and lower than the gelation temperature T2.

Description

Apparatus and method for producing gel

[0001] The present invention relates to an apparatus and method for producing a gel used in producing a porous silica material having macropores.

[0002] Porous silica materials (silica monoliths) having macropores are widely used in chromatographic separation columns, enzyme carriers, catalyst carriers, adsorbents, and the like.

[0003] A porous silica material having macropores has a co-continuous structure of a skeleton made of silica and macropores.

[0004] Porous silica materials having macropores can be produced, for example, by the following method. First, a mixed solution containing reagents such as a silica precursor, a catalyst, and a macropore-forming agent is prepared, and hydrolysis and polycondensation reactions are allowed to proceed. As the hydrolysis and polycondensation reactions proceed, nanometer-sized siloxane oligomer primary particles are formed, and secondary particles are formed by aggregation of the primary particles. This results in the formation of a sol. As the hydrolysis and polycondensation reactions proceed further, a siloxane polymer is formed, and a sol-gel transition accompanied by a phase separation process (typically spinodal decomposition) is induced. The sol-gel transition accompanied by the phase separation process forms a gel (wet gel) having a co-continuous structure of a skeletal phase and a solvent phase. Porous silica materials having macropores can be produced by drying, if necessary, the gel having a co-continuous structure of a skeletal phase and a solvent phase, followed by calcination. The skeleton of the porous silica material is formed from the skeletal phase of the gel, and the macropores of the porous silica material are formed from the solvent phase of the gel.

[0005] Patent Document 1 discloses a technique in which a mixed liquid containing reagents such as a silica precursor, a catalyst, and a macropore-forming agent is prepared in a mixing section, and the mixed liquid flowing through a discharge pipe connected to the mixing section is cooled to 35° C. or less while being discharged from the mixing section through a discharge pipe connected to the mixing section. According to the technique described in Patent Document 1, the mixed liquid is effectively cooled while the solation of the mixed liquid is promoted under well-controlled conditions, making it possible to industrially produce a homogeneous sol.

[0006] International Publication No. 2022 / 163831

[0007] The present inventors have found that there is room for improvement in the technology described in Patent Document 1. Specifically, the present inventors have found that when the sol is gelled in the gel production section, reaction heat is generated, and therefore the sol-gel transition may proceed locally without a phase separation process before a homogeneous gel is formed, resulting in the formation of a heterogeneous gel. If a heterogeneous gel is formed, the formation of a co-continuous structure between the skeleton phase and the solvent phase in the gel, and ultimately the formation of macropores in the porous silica material, will be non-uniform or insufficient. These problems are particularly an obstacle to the industrial production of porous silica materials.

[0008] Therefore, an object of the present invention is to provide a gel production apparatus and a gel production method that can industrially produce a homogeneous gel.

[0009] In order to solve the above problems, the present invention provides the following apparatus and method. [1] A gel production apparatus for producing a gel used in producing a porous silica material having macropores, the gel production apparatus comprising: a sol production unit, a sol production pipe for supplying the sol produced in the sol production unit to the gel production unit, and a temperature control unit for controlling the temperature of the sol flowing through the sol supply pipe, the sol production unit producing a sol at temperature T1 from a mixed solution containing a silica precursor, a catalyst, and a macropore-forming agent, the gel production unit producing a gel by controlling the temperature of the sol supplied through the sol supply pipe to gelation temperature T2, and the temperature control unit controlling the temperature of the sol flowing through the sol supply pipe to temperature T3 above temperature T1 and below gelation temperature T2. [2] The gel production apparatus according to [1], wherein the temperature control unit controls the temperature of the sol flowing through the sol supply pipe for 5 seconds or more. [3] The gel production apparatus according to [1] or [2], wherein temperature T3 is 19.0°C or higher and 27.1°C or lower. [4] The gel manufacturing apparatus according to any one of [1] to [3], wherein the difference between temperature T3 and temperature T1 is 1.0° C. or more, and the difference between gelation temperature T2 and temperature T3 is 0.1° C. or more. [5] The gel manufacturing apparatus according to any one of [1] to [4], wherein the gel manufacturing unit comprises: a gel formation vessel that contains the sol supplied by the sol supply pipe; and a thermostatic chamber that contains the gel formation vessel, the thermostatic chamber controlling the temperature of the sol in the gel formation vessel to gelation temperature T2. [6] The gel manufacturing apparatus according to [5], wherein the temperature control of the sol in the gel formation vessel is performed only by a temperature-regulating gas in the thermostatic chamber. [7] The gel manufacturing apparatus according to any one of [1] to [6], wherein the sol manufacturing unit comprises: a mixing unit that prepares a mixed solution containing the silica precursor, the catalyst, and the macropore-forming agent; a first supply unit that supplies the silica precursor to the mixing unit; a second supply unit that supplies the catalyst and the macropore-forming agent to the mixing unit in a mixed state or separately; a discharge pipe that discharges the mixed solution from the mixing unit; and a temperature control unit that controls the temperature of the mixed solution flowing through the discharge pipe to a predetermined temperature.[8] A method for producing a gel used in producing a porous silica material having macropores, the method comprising the following steps: (1) producing a sol at a temperature T1 from a mixed solution containing a silica precursor, a catalyst, and a macropore-forming agent; (2) supplying the sol produced in step (1) to a gel production section through a sol supply pipe; and (3) producing a gel in the gel production section by controlling the temperature of the sol supplied through the sol supply pipe to a gelation temperature T2, wherein in step (2), the temperature of the sol flowing through the sol supply pipe is controlled to a temperature T3 higher than temperature T1 and lower than gelation temperature T2. [9] The method according to [8], wherein in step (2), the temperature control of the sol flowing through the sol supply pipe is performed for 5 seconds or more.

[10] The method according to [8] or [9], wherein temperature T3 is 19.0°C or higher and 27.1°C or lower.

[11] The method according to any one of [8] to

[10] , wherein the difference between temperature T3 and temperature T1 is 1.0° C. or more, and the difference between gelation temperature T2 and temperature T3 is 0.1° C. or more.

[12] The method according to any one of [8] to

[11] , wherein the gel production unit comprises: a gel formation vessel that contains the sol supplied by the sol supply pipe; and a thermostatic chamber that contains the gel formation vessel, the thermostatic chamber controlling the temperature of the sol in the gel formation vessel to gelation temperature T2.

[13] The method according to

[12] , wherein the temperature control of the sol in the gel formation vessel is performed only by a temperature-regulating gas in the thermostatic chamber.

[14] The method according to any one of [8] to

[13] , wherein step (1) comprises the following steps: (1a) supplying the silica precursor to a mixing section; (1b) supplying the catalyst and the macropore-forming agent to the mixing section in a mixed state or separately; (1c) preparing a mixed liquid containing the silica precursor, the catalyst, and the macropore-forming agent in the mixing section; and (1d) discharging the mixed liquid from the mixing section through a discharge pipe connected to the mixing section, while controlling the temperature of the mixed liquid flowing through the discharge pipe to a predetermined temperature.

[0010] According to the present invention, there are provided a gel production apparatus and a gel production method that can industrially produce a homogeneous gel.

[0011] FIG. 1 is a schematic diagram showing the configuration of a gel production apparatus according to one embodiment. FIG. 2 is a schematic diagram showing the configuration of a sol production unit according to one embodiment. FIG. 3 is a schematic diagram showing a modified example of the sol production unit shown in FIG. 2. FIG. 4 is a schematic diagram showing the configuration of a temperature control unit according to one embodiment. FIG. 5 is a schematic diagram showing the configuration of a gel production unit according to the first embodiment. FIG. 6 is a schematic diagram showing the configuration of a gel production unit according to the second embodiment. FIG. 7 is a schematic diagram showing the configuration of a porous silica material production apparatus according to one embodiment. FIG. 8 is an SEM image of the surface structure of a silica monolith produced in an example, observed with a scanning electron microscope (SEM). FIG. 9 is an SEM image of the surface structure of a silica monolith produced in a comparative example, observed with a scanning electron microscope (SEM).

[0012] Hereinafter, embodiments of the present invention will be described. Two or more of the embodiments described in this specification can be combined, and combinations of two or more embodiments are also encompassed by the present invention. However, the present invention is not limited to the embodiments described below.

[0013] In this specification, the expression "the difference between temperature A and temperature B (temperature A - temperature B)" is used. When temperature A is set as a certain temperature range, the minimum value of the temperature range is used as temperature A to calculate the difference between temperature A and temperature B. When temperature B is set as a certain temperature range, the maximum value of the temperature range is used as temperature B to calculate the difference between temperature A and temperature B. Note that the expression "temperature A is set as a certain temperature range" means that temperature A may fluctuate within the set temperature range. The same applies to the expression "temperature B is set as a certain temperature range."

[0014] <Gel Manufacturing Apparatus> Hereinafter, a gel manufacturing apparatus 1 according to one embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the configuration of the gel manufacturing apparatus 1. Arrows in Fig. 1 indicate the direction in which the sol Z flows.

[0015] The gel production apparatus 1 is a gel production apparatus that produces a gel used to produce a porous silica material having macropores.

[0016] The gel manufacturing apparatus 1 includes a sol manufacturing unit 10, a sol supply pipe 20, a temperature control unit 30, and a gel manufacturing unit 40. The gel manufacturing apparatus 1 may include a control unit (not shown) that controls the operation of the gel manufacturing apparatus 1. The sol manufacturing unit 10 and the gel manufacturing unit 40 can be configured in the same manner as the sol manufacturing unit and the gel manufacturing unit described in WO 2022 / 163831.

[0017] The sol production unit 10 produces a sol Z at a temperature T1 from a mixed liquid M containing a silica precursor, a catalyst, and a macropore-forming agent. The sol supply pipe 20 supplies the sol Z produced in the sol production unit 10 to the gel production unit 40. The temperature control unit 30 controls the temperature of the sol Z flowing through the sol supply pipe 20 to a temperature T3 that is higher than the temperature T1 and lower than a gelation temperature T2. The gel production unit 40 produces a gel by controlling the temperature of the sol Z supplied by the sol supply pipe 20 to the gelation temperature T2.

[0018] When the sol Z is gelled in the gel production unit 40, reaction heat is generated, and the sol-gel transition may proceed locally without a phase separation process before a homogeneous gel is formed, resulting in the formation of a heterogeneous gel. If a heterogeneous gel is formed, the formation of a co-continuous structure between the skeletal phase and the solvent phase in the gel, and ultimately the formation of macropores in the porous silica body, may become uneven or insufficient. Therefore, in this embodiment, the temperature control unit 30 controls the temperature of the sol Z flowing through the sol supply pipe 20 to temperature T3, and the sol Z at temperature T3 is supplied to the gel production unit 40. In other words, the temperature of the sol Z supplied to the gel production unit 40 is brought close to the gelation temperature T2 in advance (i.e., while the sol Z is flowing through the sol supply pipe 20), and at least a portion of the reaction heat generated when the sol Z is gelled in the gel production unit 40 is removed in advance. This makes it possible to prevent the sol-gel transition from proceeding locally without a phase separation process before a homogeneous gel is formed when gelling the sol Z in the gel production unit 40, and to industrially produce a homogeneous gel. In addition, the temperature control of the sol Z required when gelling the sol Z in the gel production unit 40 becomes simple, making it possible to scale up the production of the gel.

[0019] The temperature T1, the gelation temperature T2, and the temperature T3 may each be set within a certain temperature range or may be set as a specific temperature within the temperature range. The temperature T1, the gelation temperature T2, and the temperature T3 may each be appropriately set depending on the types and / or combinations of the silica precursor, catalyst, and macropore-forming agent used, from the viewpoint of obtaining a homogeneous sol Z that enables appropriate formation of macropores.

[0020] Temperature T3 is greater than temperature T1 and less than gelation temperature T2. When temperature T1 is set as a temperature range, "greater than temperature T1" means exceeding the maximum value of the temperature range. When gelation temperature T2 is set as a temperature range, "less than gelation temperature T2" ​​means less than the minimum value of the temperature range. When temperature T3 is set as a temperature range, "greater than temperature T1 and less than gelation temperature T2" ​​means that both the minimum and maximum values ​​of the temperature range are greater than temperature T1 and less than gelation temperature T2.

[0021] From the viewpoint of obtaining a homogeneous gel that allows for the appropriate formation of macropores, the temperature T3 is preferably 19.0° C. or higher and 27.1° C. or lower, more preferably 20.0° C. or higher and 27.1° C. or lower, and even more preferably 22.0° C. or higher and 27.1° C. or lower. Each of the above lower limits may be combined with any of the above upper limits.

[0022] From the viewpoint of obtaining a homogeneous gel that enables the appropriate formation of macropores, the difference between temperature T3 and temperature T1 (temperature T3 - temperature T1) is preferably 1.0°C or more, more preferably 2.0°C or more, and even more preferably 3.0°C or more. That is, the upper limit of temperature T1 is preferably (temperature T3 - 1.0°C) or less, more preferably (temperature T3 - 2.0°C) or less, and even more preferably (temperature T3 - 3.0°C) or less. When temperature T3 is set as a temperature range, the minimum value of the temperature range is used as temperature T3, and (temperature T3 - 1.0°C), (temperature T3 - 2.0°C), and (temperature T3 - 3.0°C) are calculated.

[0023] The upper limit of the difference between temperature T3 and temperature T1 (temperature T3 - temperature T1) is determined appropriately depending on the lower limit of temperature T1. The lower limit of temperature T1 may be any temperature at which the mixed liquid M does not freeze, and may be, for example, 1°C or higher, or 2°C or higher. Each of these lower limits may be combined with any of the above upper limits.

[0024] From the viewpoint of obtaining a homogeneous gel that enables the appropriate formation of macropores, the difference between gelation temperature T2 and temperature T3 (gelation temperature T2 - temperature T3) is preferably 0.1°C or more, more preferably 0.2°C or more, and even more preferably 0.3°C or more. That is, the lower limit of gelation temperature T2 is preferably (temperature T3 + 0.1°C) or more, more preferably (temperature T3 + 0.2°C) or more, and even more preferably (temperature T3 + 0.3°C) or more. When temperature T3 is set as a temperature range, the maximum value of the temperature range is used as temperature T3, and (temperature T3 + 0.1°C), (temperature T3 + 0.2°C), and (temperature T3 + 0.3°C) are calculated.

[0025] The upper limit of the difference between the gelation temperature T2 and the temperature T3 (gelation temperature T2 - temperature T3) is determined appropriately depending on the upper limit of the gelation temperature T2. From the viewpoint of obtaining a homogeneous gel that allows for the appropriate formation of macropores, the upper limit of the gelation temperature T2 is preferably 60.0°C or less, more preferably 40.0°C or less, and even more preferably 35.0°C or less. Each of these upper limits may be combined with any of the above lower limits.

[0026] In one embodiment, the temperature T3 is 19.0°C or higher and 27.1°C or lower, the temperature T1 is 14.0°C or higher and 18.0°C or lower, preferably 14.2°C or higher and 17.0°C or lower, and more preferably 14.4°C or higher and 16.0°C or lower, and the gelation temperature T2 is 27.2°C or higher and 60.0°C or lower, preferably 27.3°C or higher and 40.0°C or lower, and more preferably 27.4°C or higher and 35.0°C or lower.

[0027] In another embodiment, the temperature T3 is 20.0°C or higher and 27.1°C or lower, the temperature T1 is 14.0°C or higher and 19.0°C or lower, preferably 14.2°C or higher and 18.0°C or lower, and more preferably 14.4°C or higher and 17.0°C or lower, and the gelation temperature T2 is 27.2°C or higher and 60.0°C or lower, preferably 27.3°C or higher and 40.0°C or lower, and more preferably 27.4°C or higher and 35.0°C or lower.

[0028] In yet another embodiment, the temperature T3 is 22.0°C or higher and 27.1°C or lower, the temperature T1 is 14.0°C or higher and 21.0°C or lower, preferably 14.2°C or higher and 20.0°C or lower, and more preferably 14.4°C or higher and 19.0°C or lower, and the gelation temperature T2 is 27.2°C or higher and 60.0°C or lower, preferably 27.3°C or higher and 40.0°C or lower, and more preferably 27.4°C or higher and 35.0°C or lower.

[0029] The above embodiments regarding temperature T1, gelation temperature T2, and temperature T3 are preferably combined with an embodiment in which the silica precursor is an alkoxysilane, more preferably with an embodiment in which the silica precursor is a tetraalkoxysilane, and even more preferably with an embodiment in which the silica precursor is tetramethoxysilane.

[0030] <Sol Production Unit> The sol production unit 10 will be described below.

[0031] The sol production unit 10 produces a sol Z at a temperature T1 from a mixed liquid M containing a silica precursor, a catalyst, and a macropore-forming agent.

[0032] The silica precursor is a silicon compound having hydrolyzable functional groups. The number of hydrolyzable functional groups possessed by the silicon compound may be 1 or 2, but from the viewpoint of producing a gel having a highly crosslinked structure with siloxane bonds (-Si-O-Si-), the number is preferably 3 or more, and more preferably 4. When the number of hydrolyzable functional groups possessed by the silicon compound is 2 or more, the types of the two or more hydrolyzable functional groups may be the same or different.

[0033] The hydrolyzable functional group is a functional group that is converted into a hydroxy group by hydrolysis. Examples of the hydrolyzable functional group include an alkoxy group, an acetoxy group, a halide group, and a hydrosilyl group, with an alkoxy group being preferred. The alkoxy group is preferably an alkoxy group having 1 to 10 carbon atoms, more preferably an alkoxy group having 1 to 5 carbon atoms, and even more preferably a methoxy group, an ethoxy group, or a propyl group. The alkoxy group may be linear or branched.

[0034] The silicon compound having a hydrolyzable functional group may have a functional group other than the hydrolyzable functional group. Examples of functional groups other than the hydrolyzable functional group include alkyl groups, alkenyl groups, phenyl groups, phenoxy groups, hydroxy groups, carboxyl groups, epoxy groups, aldehyde groups, thiol groups, amino groups, acryloyl groups, and methacryloyl groups. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and even more preferably a methyl group, an ethyl group, or a propyl group. The alkyl group may be linear or branched. The alkenyl group is preferably an alkenyl group having 2 to 10 carbon atoms, more preferably an alkenyl group having 2 to 5 carbon atoms, and even more preferably a vinyl group. The alkenyl group may be linear or branched.

[0035] The silicon compound having a hydrolyzable functional group is preferably an alkoxysilane. Examples of the alkoxysilane include tetraalkoxysilane, trialkoxysilane, dialkoxysilane, and monoalkoxysilane. Among these, from the viewpoint of facilitating the progress of the hydrolysis reaction and the polycondensation reaction, tetraalkoxysilane, trialkoxysilane, and dialkoxysilane are preferred, tetraalkoxysilane and trialkoxysilane are more preferred, and tetraalkoxysilane is even more preferred. In one embodiment, tetramethoxysilane can be used.

[0036] The catalyst functions as a catalyst for the hydrolysis reaction. Examples of the catalyst include acids and bases. Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid; and organic acids such as formic acid, acetic acid, oxalic acid, and citric acid. Examples of the base include sodium hydroxide, potassium hydroxide, aqueous ammonia, sodium carbonate, sodium bicarbonate, amines such as trimethylammonium, ammonium hydroxides such as tert-butylammonium hydroxide, and alkali metal alkoxides such as sodium methoxide.

[0037] The macropore-forming agent contributes to the formation of macropores in the porous silica material. Examples of the macropore-forming agent include water-soluble polymers and surfactants, with water-soluble polymers being preferred. The water-soluble polymer induces a sol-gel transition accompanied by a phase separation process (typically spinodal decomposition), and contributes to the formation of a co-continuous structure between the framework phase and the solvent phase in the gel, thereby contributing to the formation of macropores in the porous silica material.

[0038] Examples of water-soluble polymers include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyacrylic acid, polyethylene glycol-polypropylene glycol block copolymers, polyvinylpyrrolidone, polystyrene sulfonate sodium salt, and polyallylamine hydrochloride.

[0039] From the viewpoint of efficiently carrying out the phase separation process (typically, spinodal decomposition), the weight average molecular weight of the water-soluble polymer is preferably from 8000 to 15000. The weight average molecular weight is measured by GPC (gel permeation chromatography).

[0040] Examples of surfactants include cationic surfactants such as cetyltrimethylammonium chloride, anionic surfactants such as sodium dodecyl sulfate, and nonionic surfactants such as polyoxyethylene alkyl ether.

[0041] The mixed solution M may contain a mesopore-forming agent in addition to the silica precursor, catalyst, and macropore-forming agent. The mesopore-forming agent contributes to the formation of mesopores in the porous silica material. Examples of the mesopore-forming agent include nitrogen compounds. Examples of nitrogen compounds that can be used as mesopore-forming agents include amide compounds such as urea, formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, and N,N-dimethylacetamide; and heterocyclic compounds such as hexamethylenetetramine. Of these, urea is preferred from the viewpoint of efficient mesopore formation.

[0042] The mixed solution M may contain a solvent. In one embodiment, the solvent is water. In another embodiment, the solvent is a mixed solvent of water and an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, 2-propanol, ethylene glycol, propylene glycol, and 1,4-butanediol; and ketones such as acetone and methyl ethyl ketone. When a mixed solvent of water and an organic solvent is used as the solvent, the content of the organic solvent is preferably 65 mass% or less based on the mass of the mixed solvent.

[0043] The mixed liquid M turns into a sol as the hydrolysis reaction and polycondensation reaction proceed.

[0044] In the hydrolysis reaction, the hydrolyzable functional groups of the silica precursor are hydrolyzed to form hydroxy groups. In the polycondensation reaction, a siloxane oligomer is formed by a dehydration condensation reaction between hydroxy groups (formula (1) below) and a dealcoholization condensation reaction between a hydroxy group and an unhydrolyzed hydrolyzable functional group (formula (2) below). In formula (2) below, -OR represents an unhydrolyzed hydrolyzable functional group. ≡Si-OH + HO-Si≡ → ​​≡Si-O-Si≡ + H ２ O...(1) ≡Si-OR + HO-Si≡ → ​​≡Si-O-Si≡ + ROH...(2)

[0045] As the hydrolysis reaction and polycondensation reaction proceed further, nanometer-sized siloxane oligomer primary particles are formed, and the primary particles aggregate to form secondary particles, thereby converting the mixed liquid M into a sol.

[0046] Because the hydrolysis reaction is exothermic, the sol-gel transition may proceed locally without a phase separation process before the formation of a homogeneous sol Z, which may result in the formation of a co-continuous structure between the skeletal phase and the solvent phase in the gel, and ultimately in the formation of macropores in the porous silica material being non-uniform or insufficient. Therefore, from the perspective of obtaining a homogeneous sol Z that enables the appropriate formation of macropores, it is preferable that the sol production unit 10 prepares a mixed liquid M containing a silica precursor, a catalyst, and a macropore-forming agent, and then controls the temperature of the mixed liquid M to temperature T1 during the process of soling the mixed liquid M, thereby producing a sol Z at temperature T1.

[0047] A sol production unit 10A, which is one embodiment of the sol production unit 10, will be described below with reference to Fig. 2. Fig. 2 is a schematic diagram showing the configuration of the sol production unit 10A. Arrows in Fig. 2 indicate the direction in which a fluid such as a mixed liquid M flows.

[0048] The sol production unit 10A includes a mixing unit 11 that prepares a mixed solution M containing a silica precursor, a catalyst, and a macropore-forming agent, a first supply unit 12 that supplies the silica precursor to the mixing unit 11, a second supply unit 13 that supplies the catalyst and the macropore-forming agent in a mixed state to the mixing unit 11, a discharge pipe 14 that discharges the mixed solution M from the mixing unit 11, and a temperature control unit 15 that controls the temperature of the mixed solution M flowing through the discharge pipe 14 to a predetermined temperature (hereinafter referred to as "temperature T1a"). The sol production unit 10A may also include a recovery container 17 that recovers the mixed solution M discharged from the discharge pipe 14.

[0049] The sol production unit 10A allows the solation of the mixed liquid M to proceed under well-controlled conditions while effectively controlling the temperature of the mixed liquid M, thereby making it possible to industrially produce a homogeneous sol Z. Furthermore, using the sol Z produced in this manner, it is possible to induce a sol-gel transition accompanied by a phase separation process, thereby producing a gel having a co-continuous structure of a skeleton phase and a solvent phase, and to produce a porous silica body having macropores.

[0050] The first supply section 12 includes a tank 121 for storing a raw material liquid L1 containing a silica precursor, a supply pipe 122 for supplying the raw material liquid L1 in the tank 121 to the mixing section 11, and a pump 123 provided on the supply pipe 122.

[0051] The first supply unit 12 uses the suction and discharge forces of the pump 123 to supply the raw material liquid L1 in the tank 121 through the supply pipe 122 to the mixer 11 .

[0052] In order to obtain a homogeneous sol Z that allows for the appropriate formation of macropores, it is preferable that the first supply unit 12 continuously supplies the raw material liquid L1 to the mixing unit 11 for a predetermined period of time.

[0053] The raw material liquid L1 may contain a solvent. The above description regarding the solvent contained in the mixed liquid M also applies to the solvent contained in the raw material liquid L1.

[0054] When the silica precursor is liquid at room temperature, the raw material liquid L1 may be composed of the silica precursor alone without containing a solvent.

[0055] The second supply section 13 includes a tank 131 for storing a raw material liquid L2 containing a catalyst and a macropore-forming agent, a supply pipe 132 for supplying the raw material liquid L2 in the tank 131 to the mixing section 11, and a pump 133 provided on the supply pipe 132.

[0056] The second supply unit 13 uses the suction and discharge forces of the pump 133 to supply the raw material liquid L2 in the tank 131 to the mixing unit 11 through the supply pipe 132. That is, the second supply unit 13 supplies the catalyst and the macropore-forming agent in a mixed state to the mixing unit 11. The second supply unit 13 may supply the catalyst and the macropore-forming agent separately to the mixing unit 11.

[0057] In order to obtain a homogeneous sol Z that allows for the appropriate formation of macropores, it is preferable that the second supply unit 13 continuously supplies the raw material liquid L2 to the mixing unit 11 for a predetermined period of time.

[0058] The timing of supplying the raw material liquid L2 by the second supply unit 13 is preferably adjusted so that the catalyst and the macropore-forming agent (or, if the raw material liquid L2 contains a mesopore-forming agent, the catalyst, the macropore-forming agent, and the mesopore-forming agent) simultaneously come into contact with the silica precursor in the mixing unit 11. For example, while the first supply unit 12 continuously supplies the raw material liquid L1 to the mixing unit 11, the second supply unit 13 also continuously supplies the raw material liquid L2 to the mixing unit 11, thereby allowing the catalyst and the macropore-forming agent (or, if the raw material liquid L2 contains a mesopore-forming agent, the catalyst, the macropore-forming agent, and the mesopore-forming agent) to simultaneously come into contact with the silica precursor in the mixing unit 11.

[0059] The raw material liquid L2 may contain a solvent. The above description regarding the solvent contained in the mixed liquid M also applies to the solvent contained in the raw material liquid L2.

[0060] The raw material liquid L2 may contain a mesopore-forming agent.

[0061] When the raw material liquid L2 contains a mesopore-forming agent, the second supply unit 13 supplies the mesopore-forming agent in a mixed state with both the catalyst and the macropore-forming agent to the mixing unit 11. The second supply unit 13 may supply the mesopore-forming agent to the mixing unit 11 in a mixed state with either the catalyst or the macropore-forming agent, or separately from the catalyst and the macropore-forming agent.

[0062] The mixing section 11 includes a confluence section 111 , a mixer 112 , and a connecting pipe 113 that connects the confluence section 111 and the mixer 112 .

[0063] The confluence part 111 is a part where the supply pipe 122 and the supply pipe 132 join together. The raw material liquid L1 supplied by the supply pipe 122 and the raw material liquid L2 supplied by the supply pipe 132 join together at the confluence part 111. The confluence part 111 may be configured by, for example, a T-pipe, a Y-pipe, or the like, or may be configured by a static mixer, a dynamic mixer, or the like.

[0064] The mixer 112 includes a mixing tube 112 a and a mixing section 112 b provided inside the mixing tube 112 a. The mixer 112 is generally called a line mixer or an in-line mixer, and mixes the liquids flowing through the mixing tube 112 a by the mixing section 112 b.

[0065] One end of the connecting pipe 113 is connected to the junction 111, and the other end of the connecting pipe 113 is connected to an inlet formed at the upstream end of the mixing pipe 112a. The raw material liquids L1 and L2 that have joined at the junction 111 flow into the mixing pipe 112a through the connecting pipe 113 and the inlet of the mixing pipe 112a. Note that the connecting pipe 113 may be integrated with the pipes that make up the junction 111 and / or the mixing pipe 112a of the mixer 112 (i.e., the connecting pipe 113, the pipes that make up the junction 111 and / or the mixing pipe 112a of the mixer 112 may be formed as a single pipe).

[0066] The mixing section 112b mixes the raw material liquids L1 and L2 that flow into the mixing tube 112a and downstream inside the mixing tube 112a to prepare a mixed liquid M containing a silica precursor, a catalyst, and a macropore-forming agent. When the raw material liquid L2 contains a mesopore-forming agent, the mixed liquid M further contains the mesopore-forming agent.

[0067] The mixer 112 may be, for example, a static mixer or a dynamic mixer.

[0068] The mixed liquid M prepared by the mixing section 112b flows downstream inside the mixing pipe 112a and flows out of the mixing pipe 112a from an outlet formed at the downstream end of the mixing pipe 112a.

[0069] One end of a discharge pipe 14 is connected to the outlet of the mixing pipe 112a, and the mixed liquid M flowing out from the outlet of the mixing pipe 112a flows through the discharge pipe 14 and is discharged from the other end of the discharge pipe 14. The mixed liquid M discharged from the other end of the discharge pipe 14 is collected in a collection container 17, for example.

[0070] The temperature control unit 15 includes a jacket 151 provided on the outside of the exhaust pipe 14 and a temperature control medium 152 accommodated in the jacket 151 .

[0071] At least a portion of the exhaust pipe 14 is in contact with the temperature control medium 152. The shape of the portion of the exhaust pipe 14 that is in contact with the temperature control medium 152 may be linear, serpentine, or spiral. The exhaust pipe 14 may be composed of a single pipe, or may be composed of two or more connected pipes.

[0072] In this embodiment, the exhaust pipe 14 and the temperature control medium 152 are in direct contact with each other, but they may be in indirect contact with each other via a member made of a material with high thermal conductivity, such as metal.

[0073] In this embodiment, the jacket 151 is in the form of a tank. The form of the jacket 151 can be changed as appropriate as long as at least a part of the discharge pipe 14 can come into contact with the temperature control medium 152.

[0074] In this embodiment, the temperature control medium 152 is a liquid such as water, but may also be a gas such as air.

[0075] In this embodiment, at least a portion of the discharge pipe 14 is immersed in the temperature control medium 152 and is thereby in contact with the temperature control medium 152 .

[0076] The temperature control unit 15 controls the temperature of the mixed liquid M flowing through the discharge pipe 14 to temperature T1a by heat exchange between the temperature control medium 152 and the mixed liquid M flowing through the discharge pipe 14. By controlling the temperature of the mixed liquid M flowing through the discharge pipe 14 to temperature T1a during the process of solation of the mixed liquid M, a homogeneous sol Z that enables appropriate formation of macropores is obtained. The above description regarding temperature T1 also applies to temperature T1a. As will be described later, when one end of the sol supply pipe 20 is connected to the discharge pipe 14 (i.e., when the mixed liquid M discharged from the discharge pipe 14 is supplied to the sol supply pipe 20), the temperature T1a of the mixed liquid M discharged from the discharge pipe 14 is "temperature T1."

[0077] As long as the temperature of the mixed liquid M flowing through the discharge pipe 14 is controlled to temperature T1a, the temperature control of the mixed liquid M by the temperature control unit 15 may include cooling or heating the mixed liquid M flowing through the discharge pipe 14.

[0078] The time it takes for the temperature control unit 15 to control the temperature of the mixed liquid M flowing through the discharge pipe 14 (i.e., the time it takes for the mixed liquid M to flow through the part of the discharge pipe 14 that comes into contact with the temperature control medium 152) can be adjusted, for example, by adjusting the inner diameter and length of the part of the discharge pipe 14 that comes into contact with the temperature control medium 152, the flow rate of the mixed liquid M flowing through the discharge pipe 14, etc.

[0079] It can be confirmed that the temperature of the mixed liquid M has been controlled to the temperature T1a by detecting the temperature of the mixed liquid M immediately after the temperature control by the temperature control unit 15. The temperature of the mixed liquid M immediately after the temperature control by the temperature control unit 15 is detected, for example, after the temperature of the mixed liquid M has been controlled by the temperature control unit 15 and before the mixed liquid M is recovered in the recovery container 17.

[0080] The temperature of the temperature adjustment medium 152 is set so that the temperature of the mixed liquid M flowing through the discharge pipe 14 is controlled to temperature T1a by heat exchange. The temperature of the temperature adjustment medium 152 may be set within a certain temperature range, or may be set as a specific temperature within that temperature range. The temperature of the temperature adjustment medium 152 is usually set to a temperature lower than temperature T1a. This is because the mixed liquid M generates heat. The difference between temperature T1a and the temperature of the temperature adjustment medium 152 (temperature T1a - temperature of the temperature adjustment medium 152) is, for example, 1°C or higher and 25°C or lower, and preferably 1°C or higher and 10°C or lower.

[0081] The temperature control unit 15 may include a temperature control medium supply unit 153 that supplies a temperature control medium 152 to the jacket 151 , and a temperature control medium discharge unit 154 that discharges the temperature control medium 152 from the jacket 151 .

[0082] A thermometer 16 for detecting the temperature of the mixed liquid M flowing through the discharge pipe 14 may be provided downstream of the portion of the discharge pipe 14 that comes into contact with the temperature control medium 152. The temperature of the mixed liquid M immediately after the temperature control by the temperature control unit 15 is detected by, for example, the thermometer 16.

[0083] The temperature control unit 15 may adjust the temperature and / or flow rate of the temperature control medium 152 supplied by the temperature control medium supply unit 153, the flow rate of the temperature control medium 152 discharged by the temperature control medium discharge unit 154, etc. based on the temperature of the mixed liquid M detected by the thermometer 16.

[0084] The mixed solution M becomes a sol as the hydrolysis reaction and polycondensation reaction proceed. As the hydrolysis reaction and polycondensation reaction proceed further, nanometer-sized siloxane oligomer primary particles are formed, and the primary particles aggregate to form secondary particles. As a result, the mixed solution M becomes a sol.

[0085] The hydrolysis reaction and polycondensation reaction start when the mixed liquid M is prepared, and proceed not only while the mixed liquid M is present in the mixing section 11, but also while the mixed liquid M flows through the discharge pipe 14. The hydrolysis reaction and polycondensation reaction proceed even after the mixed liquid M is recovered in the recovery container 17. Therefore, the mixed liquid M present in the mixing section 11, the mixed liquid M flowing through the discharge pipe 14, and the mixed liquid M in the recovery container 17 all correspond to the sol Z, but the degree of solation differs.

[0086] The configuration of the sol production unit 10A can be changed as appropriate. For example, the configuration described in WO 2022 / 163831 can be selected as the configuration of the sol production unit 10A.

[0087] In one modified example, the sol producing unit 10A includes an agitating unit 18 that agitates the mixed liquid M in the recovery container 17, as shown in FIG.

[0088] When the flow rate of the mixed liquid M is high, from the viewpoint of preparing a homogeneous sol Z that enables appropriate formation of macropores, it is preferable that the sol production unit 10A include a stirring unit 18. Specifically, when the flow rate of the mixed liquid M is 15 mL / min or more, it is preferable that the sol production unit 10A include a stirring unit 18.

[0089] The stirring unit 18 includes, for example, a shaft 181, a stirring blade 182 provided on the shaft 181, and a drive unit (not shown) that rotates the shaft 181, and the mixed liquid M in the recovery container 17 is stirred by rotating the shaft 181 and the stirring blade 182 using the drive unit.

[0090] The stirring unit 18 may be configured with a magnetic stirrer (not shown) instead of the above configuration.

[0091] In another modified example, the sol producing unit 10A includes a temperature control unit 19 that controls the temperature of the mixed liquid M in the recovery container 17 to a predetermined temperature (hereinafter referred to as "temperature T1b"), as shown in FIG.

[0092] When the flow rate of the mixed liquid M is high, it is preferable that the sol production unit 10A is provided with a temperature control unit 19 in order to ensure sufficient temperature control of the mixed liquid M.

[0093] The temperature control unit 19 includes, for example, a jacket 191 provided on the outside of the recovery container 17 and a temperature control medium 192 accommodated in the jacket 191 .

[0094] At least a portion of the recovery container 17 is in contact with the temperature control medium 192 .

[0095] In this embodiment, the recovery container 17 and the temperature adjustment medium 192 are in direct contact with each other, but they may be in indirect contact with each other via a member made of a material with high thermal conductivity, such as metal.

[0096] In this embodiment, the jacket 191 is in the form of a tank. The form of the jacket 191 can be changed as appropriate as long as at least a portion of the recovery container 17 can come into contact with the temperature adjustment medium 192.

[0097] In this embodiment, the temperature control medium 192 is a liquid such as water, but may also be a gas such as air.

[0098] In this embodiment, at least a portion of the recovery container 17 is immersed in the temperature adjustment medium 192 and is thereby in contact with the temperature adjustment medium 192 .

[0099] The temperature control unit 19 controls the temperature of the mixed liquid M in the recovery container 17 to temperature T1b by heat exchange between the temperature control medium 192 and the mixed liquid M. In the process of solation of the mixed liquid M, by controlling the temperature of the mixed liquid M in the recovery container 17 to temperature T1b, a homogeneous sol Z that enables appropriate formation of macropores is obtained. The above description regarding temperature T1 also applies to temperature T1b. As will be described later, when one end of the sol supply pipe 20 is connected to the recovery container 17 (i.e., when the mixed liquid M in the recovery container 17 is supplied to the sol supply pipe 20), the temperature T1b of the mixed liquid M in the recovery container 17 is "temperature T1."

[0100] The temperature T1b of the mixed solution M in the recovery container 17 and the temperature T1a of the mixed solution M discharged from the discharge pipe 14 may be the same or different. From the viewpoint of obtaining a homogeneous gel that enables appropriate formation of macropores, the difference between the two temperatures (temperature T1b - temperature T1a when T1b ≥ T1a, and temperature T1a - temperature T1b when T1a ≥ T1b) is preferably 0°C or higher and 10°C or lower, more preferably 0°C or higher and 7°C or lower.

[0101] As long as the temperature of the mixed liquid M in the recovery container 17 is controlled to temperature T1b, the temperature control of the mixed liquid M by the temperature control unit 19 may include cooling or heating the mixed liquid M in the recovery container 17.

[0102] The temperature of the temperature adjustment medium 192 is set so that the temperature of the mixed liquid M in the recovery container 17 is controlled to temperature T1b by heat exchange. The temperature of the temperature adjustment medium 192 may be set within a certain temperature range, or may be set as a specific temperature within that temperature range. The temperature of the temperature adjustment medium 192 is usually set to a temperature lower than temperature T1b. This is because the mixed liquid M generates heat. The difference between temperature T1b and the temperature of the temperature adjustment medium 192 (temperature T1b - temperature of the temperature adjustment medium 192) is, for example, 1°C or higher and 25°C or lower, and preferably 1°C or higher and 10°C or lower.

[0103] The temperature control unit 19 may include a temperature control medium supply unit 193 that supplies a temperature control medium 192 to the jacket 191 , and a temperature control medium discharge unit 194 that discharges the temperature control medium 192 from the jacket 191 .

[0104] Two or more of the modifications described herein may be combined, and the combination of two or more modifications is also encompassed by the present invention.

[0105] <Sol Supply Pipe> The sol supply pipe 20 will be described below.

[0106] The sol supply pipe 20 supplies the sol Z produced in the sol production unit 10 to the gel production unit 40 .

[0107] One end of the sol supply pipe 20 is connected to the sol production unit 10 , and the other end of the sol supply pipe 20 is connected to the gel production unit 40 .

[0108] When sol Z is produced by sol production unit 10A, one end of sol supply pipe 20 may be connected to discharge pipe 14 of sol production unit 10A or to recovery container 17 of sol production unit 10A.

[0109] "Sol Z produced in the sol production unit 10" means the mixed liquid M at temperature T1 discharged from the discharge pipe 14 when one end of the sol supply pipe 20 is connected to the discharge pipe 14 of the sol production unit 10A (i.e., when the mixed liquid M discharged from the discharge pipe 14 is supplied to the sol supply pipe 20), and means the mixed liquid M at temperature T1 in the recovery container 17 when one end of the sol supply pipe 20 is connected to the recovery container 17 of the sol production unit 10A (i.e., when the mixed liquid M in the recovery container 17 is supplied to the sol supply pipe 20).

[0110] When one end of the sol supply pipe 20 is connected to the discharge pipe 14 of the sol production unit 10A, the temperature T1a of the mixed liquid M discharged from the discharge pipe 14 is "temperature T1", and when one end of the sol supply pipe 20 is connected to the recovery container 17 of the sol production unit 10A, the temperature T1b of the mixed liquid M in the recovery container 17 is "temperature T1".

[0111] The sol supply pipe 20 may be provided with pumps 21 and / or 22. The pump 21 is provided in a portion of the sol supply pipe 20 that connects the sol production unit 10 and the temperature control unit 30. The pump 22 is provided in a portion of the sol supply pipe 20 that connects the temperature control unit 30 and the gel production unit 40. The sol Z produced in the sol production unit 10 is supplied to the gel production unit 40 through the sol supply pipe 20 by, for example, the suction force and discharge force of the pumps 21 and / or 22.

[0112] <Temperature Control Unit> The temperature control unit 30 will now be described.

[0113] The temperature control unit 30 controls the temperature of the sol Z flowing through the sol supply pipe 20 to a temperature T3.

[0114] The initial temperature of the sol Z flowing through the sol supply pipe 20 is temperature T1. Therefore, the temperature control of the sol Z by the temperature control unit 30 includes heating the sol Z flowing through the sol supply pipe 20. As long as the temperature of the sol Z flowing through the sol supply pipe 20 is controlled to temperature T3, the temperature control of the sol Z by the temperature control unit 30 may also include cooling the sol Z flowing through the sol supply pipe 20.

[0115] From the viewpoint of obtaining a homogeneous gel that enables appropriate formation of macropores, the time period during which the temperature control unit 30 controls the temperature of the sol Z flowing through the sol supply pipe 20 is preferably 5 seconds or more, more preferably 6 seconds or more, and even more preferably 7 seconds or more. The upper limit can be adjusted as appropriate and may be, for example, 20 seconds or less, 15 seconds or less, or 10 seconds or less. Each of these upper limits may be combined with any of the above-mentioned lower limits.

[0116] Hereinafter, a temperature control unit 30A, which is one embodiment of the temperature control unit 30, will be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing the configuration of the temperature control unit 30A. The arrows in Fig. 4 indicate the direction in which a fluid such as the sol Z flows.

[0117] The temperature control unit 30A includes a jacket 31 provided on the outside of the sol supply pipe 20 and a temperature control medium 32 accommodated in the jacket 31 .

[0118] At least a portion of the sol supply pipe 20 is in contact with the temperature control medium 32. The shape of the portion of the sol supply pipe 20 that is in contact with the temperature control medium 32 may be linear, serpentine, or spiral.

[0119] The sol supply pipe 20 may be composed of a single pipe or two or more connected pipes. For example, the first portion of the sol supply pipe 20 that comes into contact with the temperature control medium 32, the second portion that connects the first portion to the sol production unit 10, and the third portion that connects the first portion to the gel production unit 40 may each be composed of one or more pipes. For example, a heat exchanger may be used as the first portion of the sol supply pipe 20. Examples of heat exchangers include a plate heat exchanger, a multi-tube heat exchanger, a serpentine heat exchanger, and a spiral heat exchanger.

[0120] In this embodiment, the sol supply pipe 20 and the temperature control medium 32 are in direct contact with each other, but they may be in indirect contact with each other via a member made of a material with high thermal conductivity, such as metal.

[0121] In this embodiment, the jacket 31 is in the form of a tank. The form of the jacket 31 can be changed as appropriate as long as at least a part of the sol supply pipe 20 can come into contact with the temperature control medium 32.

[0122] In this embodiment, the temperature control medium 32 is a liquid such as water, but may also be a gas such as air.

[0123] In this embodiment, at least a portion of the sol supply pipe 20 is immersed in the temperature control medium 32, and is thereby in contact with the temperature control medium 32. The means for bringing at least a portion of the sol supply pipe 20 into contact with the temperature control medium 32 is not limited to immersion. For example, when a heat exchanger is used as the first portion of the sol supply pipe 20, the temperature control medium 32 may be supplied to the heat exchanger. Note that when an immersion-type heat exchanger is used as the first portion of the sol supply pipe 20, the immersion-type heat exchanger is immersed in the temperature control medium 32.

[0124] The temperature control unit 30A controls the temperature of the sol Z flowing through the sol supply pipe 20 to a temperature T3 by heat exchange between the temperature control medium 32 and the sol Z flowing through the sol supply pipe 20.

[0125] The time it takes for the temperature control unit 30A to control the temperature of the sol Z flowing through the sol supply pipe 20 (i.e., the time it takes for the sol Z to flow through the part of the sol supply pipe 20 that comes into contact with the temperature control medium 32) can be adjusted, for example, by adjusting the inner diameter and length of the part of the sol supply pipe 20 that comes into contact with the temperature control medium 32, the flow rate of the sol Z flowing through the sol supply pipe 20, etc.

[0126] It can be confirmed that the temperature of the sol Z has been controlled to temperature T3 by the temperature control unit 30A by detecting the temperature of the sol Z immediately after the temperature control by the temperature control unit 30A. The temperature of the sol Z immediately after the temperature control by the temperature control unit 30A is detected, for example, after the temperature of the sol Z has been controlled by the temperature control unit 30A and before the sol Z is supplied to the gel production unit 40.

[0127] The temperature of the temperature control medium 32 is set so that the temperature of the sol Z flowing through the sol supply pipe 20 is controlled to temperature T3 by heat exchange. The temperature of the temperature control medium 32 may be set within a certain temperature range, or may be set to a specific temperature within that temperature range. The temperature of the temperature control medium 32 is usually set to a temperature lower than temperature T3. This is because the sol Z generates heat due to the hydrolysis reaction. The difference between temperature T3 and the temperature of the temperature control medium 32 (temperature T3 - temperature of the temperature control medium 32) is, for example, 1°C or higher and 25°C or lower, and preferably 1°C or higher and 10°C or lower.

[0128] The temperature control unit 30A may include a temperature control medium supply unit 33 that supplies the temperature control medium 32 to the jacket 31 and a temperature control medium discharge unit 34 that discharges the temperature control medium 32 from the jacket 31.

[0129] A thermometer 23 for detecting the temperature of the sol Z flowing through the sol supply pipe 20 may be provided downstream of the portion of the sol supply pipe 20 that comes into contact with the temperature control medium 32. The temperature of the sol Z immediately after being temperature-controlled by the temperature control unit 30A is detected by the thermometer 23, for example.

[0130] The temperature control unit 30A may adjust the temperature of the temperature control medium 32 based on the temperature of the sol Z detected by the thermometer 23. For example, the temperature control unit 30A may adjust the temperature and / or flow rate of the temperature control medium 32 supplied by the temperature control medium supply unit 33, the flow rate of the temperature control medium 32 discharged by the temperature control medium discharge unit 34, etc. based on the temperature of the sol Z detected by the thermometer 23.

[0131] <Gel-producing section> The gel-producing section 40 will be described below.

[0132] The sol Z at a temperature T3 is supplied to the gel production unit 40 by the sol supply pipe 20. The gel production unit 40 controls the temperature of the sol Z supplied by the sol supply pipe 20 to a gelation temperature T2 to produce a gel.

[0133] By controlling the temperature of the sol Z to the gelation temperature T2, the hydrolysis reaction and polycondensation reaction proceed further to form a polysiloxane polymer, inducing a sol-gel transition accompanied by a phase separation process (typically spinodal decomposition), and producing a polysiloxane gel (wet gel). The produced polysiloxane gel has a co-continuous structure of a skeletal phase and a solvent phase. The skeletal phase is rich in the siloxane polymer produced by the hydrolysis reaction and polycondensation reaction, and the solvent phase is rich in the solvent. The skeletal phase and the solvent phase each have a continuous three-dimensional network structure and are entangled with each other, thereby forming a co-continuous structure of the skeletal phase and the solvent phase.

[0134] The initial temperature of the sol Z supplied to the gel production unit 40 by the sol supply pipe 20 is temperature T3. Therefore, the temperature control of the sol Z by the gel production unit 40 includes heating the sol Z. As long as the temperature of the sol Z is controlled to the gelation temperature T2, the temperature control of the sol Z by the gel production unit 40 may also include cooling the sol Z.

[0135] From the viewpoint of obtaining a homogeneous gel that enables the proper formation of macropores, the time for which the gel production unit 40 controls the temperature of the sol Z to the gelation temperature T2 is preferably 10 minutes or more and 30 hours or less, more preferably 4 hours or more and 24 hours or less.

[0136] A gel production unit 40A, which is a first embodiment of the gel production unit 40, will be described below with reference to Fig. 5. Fig. 5 is a schematic diagram showing the configuration of the gel production unit 40A. Arrows in Fig. 5 indicate the direction in which a fluid such as the sol Z flows.

[0137] The gel production unit 40A includes a temperature control unit 41A that controls the temperature of the sol Z supplied by the sol supply pipe 20 to a gelation temperature T2.

[0138] The temperature control unit 41A includes a gel formation vessel 411A that contains the sol Z, a jacket 412A provided on the outside of the gel formation vessel 411A, and a temperature control medium 413A contained in the jacket 412A.

[0139] At least a portion of the gel formation container 411A is in contact with the temperature adjustment medium 413A.

[0140] In this embodiment, the gel formation container 411A and the temperature adjustment medium 413A are in direct contact with each other, but they may be in indirect contact with each other via a member made of a material with high thermal conductivity such as metal.

[0141] In this embodiment, the jacket 412A is in the form of a tank. The form of the jacket 412A can be changed as appropriate as long as at least a part of the gel formation container 411A can come into contact with the temperature adjustment medium 413A.

[0142] In this embodiment, the temperature control medium 413A is a liquid such as water, but may also be a gas such as air.

[0143] In this embodiment, at least a portion of the gel formation container 411A is immersed in the temperature adjustment medium 413A, and is thereby in contact with the temperature adjustment medium 413A.

[0144] The temperature control unit 41A controls the temperature of the sol Z in the gel formation container 411A to a gelation temperature T2 by heat exchange between the temperature control medium 413A and the sol Z. As a result, the sol Z in the gel formation container 411A gels, and a gel is formed.

[0145] As long as the temperature of the sol Z in the gel formation container 411A is controlled to the gelation temperature T2, the temperature control of the sol Z by the temperature control unit 41A may include heating or cooling the sol Z in the gel formation container 411A.

[0146] The temperature of the temperature-regulating medium 413A is set so that the temperature of the sol Z in the gel formation container 411A is controlled to the gelation temperature T2 by heat exchange. The temperature of the temperature-regulating medium 413A may be set within a certain temperature range, or may be set as a specific temperature within that temperature range. The temperature of the temperature-regulating medium 413A is typically set to the gelation temperature T2. Depending on the types and / or combinations of the silica precursor, catalyst, and macropore-forming agent used, the physical properties of the desired porous silica body, and the like, the temperature of the temperature-regulating medium 413A may be set to a temperature below the gelation temperature T2 or a temperature above the gelation temperature T2. When the temperature of the temperature-regulating medium 413A is set to a temperature below the gelation temperature T2, the difference between the gelation temperature T2 and the temperature of the temperature-regulating medium 413A (gelation temperature T2 - temperature of the temperature-regulating medium 413A) is, for example, 1°C or higher and 25°C or lower, preferably 1°C or higher and 10°C or lower. When the temperature of the temperature-controlling medium 413A is set to a temperature higher than the gelling temperature T2, the difference between the temperature of the temperature-controlling medium 413A and the gelling temperature T2 (temperature of the temperature-controlling medium 413A - gelling temperature T2) is, for example, 1°C or more and 25°C or less, preferably 1°C or more and 10°C or less.

[0147] The temperature control unit 41A may include a temperature control medium supply unit 414A that supplies the temperature control medium 413A to the jacket 412A, and a temperature control medium discharge unit 415A that discharges the temperature control medium 413A from the jacket 412A.

[0148] The gel formation container 411A may include a molding mold for molding the gel into a desired shape. Examples of materials for the molding mold include synthetic resins such as polystyrene, polyethylene, polypropylene, polyethylene terephthalate (PET), polycarbonate (PC), silicone, and polytetrafluoroethylene (PTFE), and metals such as aluminum and stainless steel.

[0149] The gel production unit 40A may include a recovery container 42A that recovers the sol Z supplied by the sol supply pipe 20 (e.g., the sol Z discharged from the sol supply pipe 20), and a sol supply unit 43A that supplies the sol Z in the recovery container 42A to the gel formation container 411A.

[0150] When the gel production unit 40A does not include a recovery container 42A, the other end of the sol supply pipe 20 is connected to a gel formation container 411A, and the sol supply pipe 20 supplies the sol Z at a temperature T3 to the gel formation container 411A. The temperature control unit 41A controls the temperature of the sol Z supplied to the gel formation container 411A by the sol supply pipe 20 to a gelation temperature T2.

[0151] When the gel production unit 40A includes a recovery container 42A, the other end of the sol supply pipe 20 is connected to the recovery container 42A, and the sol supply pipe 20 supplies the sol Z at temperature T3 to the recovery container 42A.

[0152] The temperature of the sol Z in the recovery container 42A is temperature T4. Temperature T4 may be set as a certain temperature range or as a specific temperature within that temperature range. Temperatures T3 and T4 may be the same or different.

[0153] Temperature T4 (or the minimum value of temperature T4 if temperature T4 is set as a temperature range) is equal to or greater than temperature T3. If temperature T3 is set as a temperature range, "equal to or greater than temperature T3" means equal to or greater than the minimum value of temperature T3.

[0154] Temperature T4 (the minimum value of temperature T4 when temperature T4 is set as a temperature range) may be, for example, (temperature T3 + 1°C) or higher, or (temperature T3 + 2°C) or higher. When temperature T3 is set as a temperature range, "(temperature T3 + 1°C) or higher" means (minimum value of temperature T3 + 1°C) or higher, and "(temperature T3 + 2°C) or higher" means (minimum value of temperature T3 + 2°C) or higher.

[0155] Temperature T4 (or the maximum value of temperature T4 if temperature T4 is set as a temperature range) is less than gelation temperature T2. If gelation temperature T2 is set as a temperature range, "less than gelation temperature T2" ​​means less than the minimum value of gelation temperature T2. If temperature T3 is set as a temperature range, temperature T4 (or the maximum value of temperature T4 if temperature T4 is set as a temperature range) may be less than or equal to the maximum value of temperature T3, or may be greater than the maximum value of temperature T3, as long as it is less than gelation temperature T2.

[0156] From the viewpoint of obtaining a homogeneous gel that allows for the appropriate formation of macropores, temperature T4 (when temperature T4 is set as a temperature range, the maximum value of temperature T4) is preferably not more than (gelation temperature T2 - 0.1°C), more preferably not more than (gelation temperature T2 - 0.2°C), and even more preferably not more than (gelation temperature T2 - 0.3°C). When gelation temperature T2 is set as a temperature range, the minimum value of gelation temperature T2 is used as gelation temperature T2 to calculate (gelation temperature T2 - 0.1°C), (gelation temperature T2 - 0.2°C), and (gelation temperature T2 - 0.3°C).

[0157] In one embodiment, the temperature T3 is 19.0°C or higher and 27.1°C or lower, the temperature T1 is 14.0°C or higher and 18.0°C or lower, preferably 14.2°C or higher and 17.0°C or lower, and more preferably 14.4°C or higher and 16.0°C or lower, the gelation temperature T2 is 27.2°C or higher and 60.0°C or lower, preferably 27.3°C or higher and 40.0°C or lower, and more preferably 27.4°C or higher and 35.0°C or lower, and the temperature T4 is 19.0°C or higher and 27.1°C or lower, preferably 20.0°C or higher and 27.1°C or lower, and more preferably 22.0°C or higher and 27.1°C or lower.

[0158] In another embodiment, the temperature T3 is 20.0°C or higher and 27.1°C or lower, the temperature T1 is 14.0°C or higher and 19.0°C or lower, preferably 14.2°C or higher and 18.0°C or lower, and more preferably 14.4°C or higher and 17.0°C or lower, the gelation temperature T2 is 27.2°C or higher and 60.0°C or lower, preferably 27.3°C or higher and 40.0°C or lower, and more preferably 27.4°C or higher and 35.0°C or lower, and the temperature T4 is 20.0°C or higher and 27.1°C or lower, and preferably 22.0°C or higher and 27.1°C or lower.

[0159] In yet another embodiment, the temperature T3 is 22.0°C or higher and 27.1°C or lower, the temperature T1 is 14.0°C or higher and 21.0°C or lower, preferably 14.2°C or higher and 20.0°C or lower, and more preferably 14.4°C or higher and 19.0°C or lower, the gelation temperature T2 is 27.2°C or higher and 60.0°C or lower, preferably 27.3°C or higher and 40.0°C or lower, and more preferably 27.4°C or higher and 35.0°C or lower, and the temperature T4 is 22.0°C or higher and 27.1°C or lower.

[0160] The sol supply unit 43A includes a supply pipe 431A that supplies the sol Z in the recovery container 42A to the gel formation container 411A, and a pump 432A provided on the supply pipe 431A. The sol supply unit 43A uses the suction force and discharge force of the pump 432A to supply the sol Z in the recovery container 42A to the gel formation container 411A through the supply pipe 431A.

[0161] When the sol Z at a temperature T4 in the recovery container 42A is supplied to the gel formation container 411A by the sol supply unit 43A, the initial temperature of the sol Z supplied to the gel formation container 411A by the sol supply unit 43A is temperature T4. The temperature control unit 41A controls the temperature of the sol Z supplied to the gel formation container 411A by the sol supply unit 43A to a gelation temperature T2.

[0162] The gel production unit 40A may include a stirring unit 44 that stirs the sol Z in the recovery container 42A. By including the stirring unit 44 in the gel production unit 40A, local temperature variations in the sol Z in the recovery container 42A can be suppressed.

[0163] The stirring unit 44 includes, for example, a shaft 441, a stirring blade 442 provided on the shaft 441, and a drive unit (not shown) that rotates the shaft 441, and the sol Z in the recovery container 42 is stirred by rotating the shaft 441 and the stirring blade 442 using the drive unit.

[0164] The stirring unit 44 may be configured with a magnetic stirrer (not shown) instead of the above configuration.

[0165] A gel producing unit 40B, which is a second embodiment of the gel producing unit 40, will be described below with reference to Fig. 6. Fig. 6 is a schematic diagram showing the configuration of the gel producing unit 40B. The arrows in Fig. 6 indicate the direction in which the sol Z flows.

[0166] The gel production unit 40B includes a temperature control unit 41B that controls the temperature of the sol Z supplied by the sol supply pipe 20 to a gelation temperature T2.

[0167] The temperature control unit 41B includes a gel formation container 411B that contains the sol Z, and a temperature-controlled chamber 412B that contains the gel formation container 411B.

[0168] At least a portion of the gel formation container 411B is in contact with a temperature-controlled gas G (for example, temperature-controlled air) in the temperature-controlled room 412B.

[0169] In this embodiment, the gel formation container 411B and the temperature-controlled gas G in the temperature-controlled chamber 412B are in direct contact with each other, but may also be in indirect contact with each other via a member made of a material with high thermal conductivity, such as metal.

[0170] The temperature control unit 41B controls the temperature of the sol Z in the gel formation container 411B to a gelation temperature T2 by heat exchange between the sol Z in the gel formation container 411B and the temperature-controlled gas G in the temperature-controlled chamber 412B. As a result, the sol Z in the gel formation container 411B gels, and a gel is formed.

[0171] As long as the temperature of the sol Z in the gel formation container 411B is controlled to the gelation temperature T2, the temperature control of the sol Z by the temperature control unit 41B may include heating or cooling the sol Z in the gel formation container 411B.

[0172] The temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B is set so that the temperature of the sol Z in the gel formation container 411B is controlled to the gelation temperature T2 by heat exchange. The temperature of the temperature-controlled gas G may be set within a certain temperature range, or may be set to a specific temperature within that temperature range. The temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B is usually set to the gelation temperature T2. Depending on the types and / or combinations of the silica precursor, catalyst, and macropore-forming agent used, the physical properties of the desired porous silica body, and the like, the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B may be set to a temperature below the gelation temperature T2 or a temperature above the gelation temperature T2. When the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B is set to a temperature below the gelation temperature T2, the difference between the gelation temperature T2 and the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B (gelation temperature T2 - temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B) is, for example, 1° C. or more and 25° C. or less, and preferably 1° C. or more and 10° C. or less. When the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B is set to a temperature exceeding the gelation temperature T2, the difference between the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B and the gelation temperature T2 (temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B - gelation temperature T2) is, for example, 1° C. or more and 25° C. or less, and preferably 1° C. or more and 10° C. or less.

[0173] It is preferable that the temperature of the sol Z in the gel formation container 411B is controlled only by the temperature-controlled gas G in the temperature-controlled chamber 412B. This makes it easier to scale up the production of the gel. When the temperature of the sol Z in the gel formation container 411B is controlled only by the temperature-controlled gas G in the temperature-controlled chamber 412B, no heating or cooling means other than the temperature-controlled gas G is used.

[0174] In this embodiment, the temperature control unit 30 controls the temperature of the sol Z flowing through the sol supply pipe 20 to temperature T3, and the sol Z at temperature T3 is supplied to the gel production unit 40B. That is, the temperature of the sol Z supplied to the gel production unit 40B is brought close to the gelation temperature T2 in advance (i.e., while the sol Z is flowing through the sol supply pipe 20), and at least a portion of the reaction heat generated when gelling the sol Z is removed while the sol Z is flowing through the sol supply pipe 20. This simplifies the temperature control of the sol Z required to gel the sol Z in the gel production unit 40B, and makes it possible to control the temperature of the sol Z in the gel formation container 411B using only the temperature-controlled gas G in the constant-temperature chamber 412B.

[0175] The gel formation container 411B may include a molding mold for molding the gel into a desired shape. The description of the molding mold is the same as above.

[0176] The gel production unit 40B may include a recovery container 42B that recovers the sol Z supplied by the sol supply pipe 20 (e.g., the sol Z discharged from the sol supply pipe 20), and a sol supply unit 43B that supplies the sol Z in the recovery container 42B to the gel formation container 411B.

[0177] When the gel production unit 40B does not include a recovery container 42B, the other end of the sol supply pipe 20 is connected to a gel formation container 411B, and the sol supply pipe 20 supplies the sol Z at a temperature T3 to the gel formation container 411B. The temperature control unit 41B controls the temperature of the sol Z supplied to the gel formation container 411B by the sol supply pipe 20 to a gelation temperature T2.

[0178] When the gel production unit 40B includes a recovery container 42B, the other end of the sol supply pipe 20 is connected to the recovery container 42B, and the sol supply pipe 20 supplies the sol Z at temperature T3 to the recovery container 42B.

[0179] The temperature of the sol Z in the recovery container 42B is a temperature T4. The temperature T4 has been described above.

[0180] The sol supply unit 43B includes a supply pipe 431B that supplies the sol Z in the recovery container 42B to the gel formation container 411B, and a pump 432B provided on the supply pipe 431B. The sol supply unit 43B uses the suction force and discharge force of the pump 432B to supply the sol Z in the recovery container 42B to the gel formation container 411B through the supply pipe 431B.

[0181] When the sol Z at a temperature T4 in the recovery container 42B is supplied to the gel formation container 411B by the sol supply unit 43B, the initial temperature of the sol Z supplied to the gel formation container 411B by the sol supply unit 43B is temperature T4. The temperature control unit 41B controls the temperature of the sol Z supplied to the gel formation container 411B by the sol supply unit 43B to a gelation temperature T2.

[0182] The gel production unit 40B may include a stirring unit 44 that stirs the sol Z in the recovery container 42B. By including the stirring unit 44 in the gel production unit 40B, local temperature variations in the sol Z in the recovery container 42B can be suppressed. The explanation regarding the stirring unit 44 is the same as above.

[0183] <Porous Silica Material Producing Apparatus> A porous silica material producing apparatus 5 according to one embodiment will be described below with reference to Fig. 7. Fig. 7 is a schematic diagram showing the configuration of the porous silica material producing apparatus 5. The dashed line in Fig. 7 indicates the direction in which the gel is transported.

[0184] The porous silica material producing apparatus 5 is an apparatus for producing a porous silica material having macropores.

[0185] The porous silica material producing apparatus 5 includes a calcination section 51 that produces a porous silica material by calcining the gel produced by the gel production apparatus 1. The porous silica material producing apparatus 5 may include a control section (not shown) that controls the operation of the porous silica material producing apparatus 5. The porous silica material producing apparatus 5 may include the gel production apparatus 1. The porous silica material producing apparatus 5 may include a heating and reflux section 52 that reacts the gel produced by the gel production apparatus 1 with a mesopore-forming agent under heating and reflux conditions.

[0186] The calcination section 51 may calcinate the gel treated in the heating and refluxing section 52 to produce a porous silica body.

[0187] The baking temperature in the baking unit 51 is, for example, 500° C. to 1000° C., and the baking time in the baking unit 51 is, for example, 1 hour to 8 hours. The baking in the baking unit 51 is usually performed in an air atmosphere.

[0188] The heating and refluxing section 52 reacts the gel produced by the gel production apparatus 1 with the mesopore-forming agent under heating and refluxing conditions. As a result, pores (pores that become mesopores in the porous silica material) are formed in the gel skeleton. The mesopore-forming agent may be contained in the gel produced by the gel production apparatus 1, in the aqueous medium (e.g., water) that is heated and refluxed, or in both.

[0189] The heating temperature in the heating reflux section 52 is, for example, 50° C. or higher and 120° C. or lower, and the heating time is, for example, 1 hour or higher and 36 hours or lower.

[0190] <Gel Production Method> Hereinafter, a description will be given of a gel production method carried out by the gel production apparatus 1. The above description of the gel production apparatus 1 also applies to the gel production method carried out by the gel production apparatus 1, unless otherwise specified.

[0191] The gel production method includes the following steps: (1) producing a sol Z at a temperature T1 from a mixed liquid M containing a silica precursor, a catalyst, and a macropore-forming agent; (2) supplying the sol Z produced in step (1) to a gel production unit 40 through a sol supply pipe 20; and (3) producing a gel in the gel production unit 40 by controlling the temperature of the sol Z supplied through the sol supply pipe 20 to a gelation temperature T2, wherein in step (2), the temperature of the sol Z flowing through the sol supply pipe 20 is controlled to a temperature T3 that is higher than the temperature T1 and lower than the gelation temperature T2.

[0192] Step (1) is performed by the sol production unit 10. The operation of the sol production unit 10 may be controlled by a control unit (not shown).

[0193] In the step (2), the temperature of the sol Z flowing through the sol supply pipe 20 is controlled by the temperature control unit 30. The operation of the temperature control unit 30 may be controlled by a control unit (not shown).

[0194] Step (3) is performed by the gel production unit 40. The operation of the gel production unit 40 may be controlled by a control unit (not shown).

[0195] In step (2), sol Z at temperature T3 may be supplied to the gel formation container 411A via the sol supply pipe 20, and in step (3), the temperature of the sol Z in the gel formation container 411A may be controlled to gelation temperature T2 by the temperature control unit 41A to produce a gel.

[0196] In step (2), the sol Z at temperature T3 may be supplied to the recovery container 42A by the sol supply pipe 20, and in step (3), the sol Z at temperature T4 in the recovery container 42A may be supplied to the gel formation container 411A by the sol supply unit 43A, and the temperature of the sol Z in the gel formation container 411A may be controlled to gelation temperature T2 by the temperature control unit 41A to produce a gel. In step (3), the sol Z in the recovery container 42A may be stirred by the stirring unit 44. This makes it possible to suppress local temperature variations in the sol Z in the recovery container 42A.

[0197] In step (2), sol Z at temperature T3 may be supplied to the gel formation container 411B via the sol supply pipe 20, and in step (3), the temperature of the sol Z in the gel formation container 411B may be controlled to gelation temperature T2 by the temperature control unit 41B to produce a gel.

[0198] In step (2), the sol Z at temperature T3 may be supplied to the recovery container 42B by the sol supply pipe 20, and in step (3), the sol Z at temperature T4 in the recovery container 42B may be supplied to the gel formation container 411B by the sol supply unit 43B, and the temperature of the sol Z in the gel formation container 411B may be controlled to gelation temperature T2 by the temperature control unit 41B to produce a gel. In step (3), the sol Z in the recovery container 42B may be stirred by the stirring unit 44. This makes it possible to suppress local temperature variations in the sol Z in the recovery container 42B.

[0199] In step (3), if necessary, a molding mold for molding the gel into a desired shape may be added to the gel-forming container 411A or 411B.

[0200] After step (3), a step of drying the wet gel produced in step (3) to obtain a dry gel may be carried out. Examples of drying methods include natural drying, heat drying, drying using a low surface tension solvent, drying by freeze sublimation, and supercritical drying.

[0201] In one embodiment, step (1) includes the following steps: (1a) supplying a silica precursor to the mixing section 11; (1b) supplying a catalyst and a macropore-forming agent to the mixing section 11 in a mixed state or separately; (1c) preparing a mixed liquid M containing the silica precursor, the catalyst, and the macropore-forming agent in the mixing section 11; and (1d) discharging the mixed liquid M from the mixing section 11 through a discharge pipe 14 connected to the mixing section 11, while controlling the temperature of the mixed liquid M flowing through the discharge pipe 14 to a temperature T1a.

[0202] Steps (1a) to (1d) are performed by a sol production unit 10 A. The operation of the sol production unit 10 A may be controlled by a control unit (not shown).

[0203] After the step (1d), the mixed liquid M discharged from the discharge pipe 14 may be collected in a collection container 17.

[0204] After step (1d), a step (hereinafter referred to as "step (1e)") of stirring the mixed liquid M in the recovery container 17 using the stirring unit 18 may be performed. This allows the solation of the mixed liquid M to proceed to a desired extent, and makes it possible to prepare a homogeneous sol Z that allows for the appropriate formation of macropores. When the flow rate of the mixed liquid M is high, it is preferable to perform step (1e). Specifically, when the flow rate of the mixed liquid M is 15 mL / min or more, it is preferable to perform step (1e).

[0205] The stirring time by the stirring unit 18 is preferably 1 minute or more and 50 minutes or less from the viewpoint of properly carrying out the sol-gel reaction.

[0206] After step (1d), a step (hereinafter referred to as "step (1f)") of controlling the temperature of the mixed liquid M in the recovery container 17 to temperature T1b by the temperature control unit 19 may be carried out. In the process of converting the mixed liquid M into a solubilization solution, by controlling the temperature of the mixed liquid M in the recovery container 17 to temperature T1b, a homogeneous sol Z that enables appropriate formation of macropores can be obtained. When the flow rate of the mixed liquid M is high, it is preferable to carry out step (1f).

[0207] After step (1d), steps (1e) and (1f) may be performed simultaneously. That is, after step (1d), the mixed liquid M in the recovery container 17 may be stirred by the stirring unit 18 while the temperature of the mixed liquid M in the recovery container 17 is controlled to temperature T1b by the temperature control unit 19.

[0208] <<Method for Producing Porous Silica Material>> Hereinafter, a method for producing a porous silica material carried out by the porous silica material producing apparatus 5 will be described.

[0209] The method for producing a porous silica material includes the following steps: (4) producing a gel using the gel production apparatus 1; and (5) firing the gel produced in step (4) to produce a porous silica material.

[0210] Step (4) includes steps (1) to (3) of the gel production method. Step (4) is performed by the gel production apparatus 1. The operation of the gel production apparatus 1 may be controlled by a control unit (not shown).

[0211] Step (5) is performed by the baking unit 51. The operation of the baking unit 51 may be controlled by a control unit (not shown).

[0212] In step (5), the firing temperature is, for example, 500° C. to 1000° C., and the firing time is, for example, 1 hour to 8 hours. The firing is usually carried out in an air atmosphere.

[0213] After step (4) and before step (5), a step of reacting the gel produced in step (4) with a mesopore-forming agent under heating and reflux conditions (hereinafter referred to as the "heating and refluxing step") may be carried out. The heating and refluxing step is carried out by the heating and refluxing unit 52. By reacting the gel produced in step (4) with the mesopore-forming agent under heating and reflux conditions, pores (pores that will become mesopores in the porous silica material) are formed in the gel skeleton. The mesopore-forming agent may be contained in the gel produced in step (4), in the aqueous medium (e.g., water) that is heated and refluxed, or in both.

[0214] In the heating and refluxing step, the heating temperature is, for example, 50° C. or more and 120° C. or less, and the heating time is, for example, 1 hour or more and 36 hours or less.

[0215] A porous silica material (silica monolith) has a bicontinuous structure of a silica skeleton and macropores. By calcining the gel, the silica skeleton of the porous silica material is formed from the skeletal phase of the gel, and the macropores of the porous silica material are formed from the solvent phase of the gel. The porous silica material may have mesopores formed in the silica skeleton.

[0216] In a porous silica material, the silica skeleton and macropores each have a continuous three-dimensional network structure and are entangled with each other, thereby forming a co-continuous structure of the silica skeleton and macropores. The fact that the porous silica material has a co-continuous structure of the silica skeleton and macropores can be confirmed by observing the surface or cross section of the porous silica material with a scanning electron microscope (SEM).

[0217] "Mesopores" refer to pores having a pore diameter of less than 50 nm, and "macropores" refer to pores having a pore diameter of 50 nm or more. The lower limit of the pore diameter of mesopores is, for example, 2 nm or more. The upper limit of the pore diameter of macropores is, for example, 1,000,000 nm or less. "Pore diameter" refers to the diameter of the pores.

[0218] From the viewpoint of maintaining the strength of the co-continuous structure, the mode pore size of the macropores is preferably 80 nm or more and 7000 nm or less, more preferably 80 nm or more and 5000 nm or less.

[0219] From the viewpoint of improving the specific surface area, the mode pore size of the mesopores is preferably 2 nm or more and 50 nm or less, more preferably 5 nm or more and 30 nm or less.

[0220] From the viewpoint of improving the performance of the porous silica material as an adsorbent or catalyst, the specific surface area of ​​the porous silica material is preferably 100 m ２ / g or more 1000m ２ / g or less, more preferably 100m ２ / g or more 800m ２ / g or less.

[0221] The specific surface area and the most frequent pore size of mesopores can be measured using, for example, a specific surface area and pore size distribution analyzer "BELSORP-miniX" manufactured by Microtrac-Bell. The amount of nitrogen adsorption and desorption at a temperature of 77 K is measured by a multipoint method to determine an adsorption / desorption isotherm, and the specific surface area and the most frequent pore size of mesopores can be calculated based on the adsorption / desorption isotherm. The specific surface area can be calculated by the BET method, and the most frequent pore size of mesopores can be calculated by the BJH method.

[0222] The most frequent pore size of the macropores can be measured by, for example, mercury intrusion porosimetry.

[0223] The produced porous silica material can be dissolved in gas (for example, vapor of organic solvents such as alcohol and ether, SO ２ , H ２ O, CO ２ The present invention can be suitably used as an adsorbent for adsorbing target substances (e.g., metals and / or metal ions) or for adsorbing target substances from liquids containing the target substances (e.g., metals and / or metal ions), as well as for catalyst carriers, enzyme carriers, chromatographic separation columns, etc.

[0224] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0225] Example 1 Example 1 was carried out using the gel production apparatus 1 shown in FIG. 1, which is equipped with the sol production unit 10A shown in FIG. 2, the temperature control unit 30A shown in FIG. 4, and the gel production unit 40B shown in FIG. 6.

[0226] (1) Preparation of Sol in Sol Production Unit 10A The sol was prepared using the sol production unit 10A. Tetramethoxysilane was used as the raw material liquid L1 supplied from the first supply unit 12. Raw material liquid L1 was continuously supplied to the mixing unit 11 at a flow rate of 330 mL / min. Raw material liquid L2 supplied from the second supply unit 13 was an aqueous solution prepared by dissolving 1921 g of polyethylene glycol 10000 (manufactured by Yakushi Chemical Co., Ltd.) as a macropore-forming agent, 1890 g of urea as a mesopore-forming agent, and 12.6 g of acetic acid as a catalyst in water to a solution weight of 24,811 g. Raw material liquid L2 was continuously supplied to the mixing unit 11 at a flow rate of 660 mL / min. A static mixer (3 / 4-N60-331-1 manufactured by Noritake Co., Ltd.) was used as the mixer 112 of the mixing unit 11. The temperature of the mixed liquid M flowing through the discharge pipe 14 was controlled by the temperature control unit 15. A Versilon tube (outer diameter 16.4 mm, inner diameter 9.5 mm) was used as the discharge pipe 14. Cooling water at 5°C was used as the temperature control medium 152 of the temperature control unit 15. The temperature of the mixed liquid M after temperature control by the temperature control unit 15 (hereinafter referred to as "temperature T1a") was measured and found to be 7.9°C.

[0227] The mixed liquid M discharged from the discharge pipe 14 was collected in the recovery container 17 for 34 minutes. Four minutes after the completion of the collection of the mixed liquid M, the agitation unit 18 started stirring (1,400 rpm) the mixed liquid M in the recovery container 17. The agitation of the mixed liquid M in the recovery container 17 was carried out for 45 minutes. From the start of collection of the mixed liquid M to the completion of stirring of the mixed liquid M, the temperature of the mixed liquid M in the recovery container 17 was controlled by the temperature control unit 19. Cooling water at 5°C was used as the temperature control medium 192 of the temperature control unit 19. The temperature of the mixed liquid M after temperature control by the temperature control unit 19 (hereinafter referred to as "temperature T1b") was measured and found to be 14.4°C. In Examples 1 to 7 and Comparative Examples 1 to 3, temperature T1b is "temperature T1."

[0228] The hydrolysis reaction and polycondensation reaction start when the mixed liquid M is prepared, and proceed not only while the mixed liquid M is present in the mixing section 11, but also while the mixed liquid M flows through the discharge pipe 14. The hydrolysis reaction and polycondensation reaction proceed even after the mixed liquid M is recovered in the recovery container 17. Therefore, the mixed liquid M present in the mixing section 11, the mixed liquid M flowing through the discharge pipe 14, and the mixed liquid M in the recovery container 17 are all sols, but the degree of solation differs. Hereinafter, the mixed liquid M in the recovery container 17 after stirring is completed will be referred to as the "sol produced in the sol production section 10A."

[0229] (2) Supply of sol produced in sol production unit 10A to gel production unit 40B The sol produced in sol production unit 10A was supplied to gel production unit 40B via sol supply pipe 20. The first section of sol supply pipe 20, which contacts the temperature control medium 32, was connected to three stainless steel cooling coils (body size: φ120 mm × 260 mm, coil inner diameter: 6 mm). The remaining sections (the second section connecting the first section to sol production unit 10A and the third section connecting the first section to gel production unit 40B) were made of polyvinyl chloride resin piping (outer diameter 15 mm, inner diameter 9 mm). The temperature of the sol flowing through sol supply pipe 20 was controlled by temperature control unit 30A. Heated water at 28.5°C was used as the temperature control medium 32 of temperature control unit 30A. The time for which the temperature control unit 30A controlled the temperature of the sol flowing through the sol supply pipe 20 (i.e., the time required for the sol Z to flow through the part of the sol supply pipe 20 that contacts the temperature control medium 32) was adjusted to 7 seconds. The temperature of the sol after temperature control by the temperature control unit 30A (hereinafter referred to as "temperature T3") was measured and found to be 24.6 to 27.1°C.

[0230] (3) Preparation of Gel in Gel Production Unit 40B The sol supplied through the sol supply pipe 20 was collected in a collection container 42B. When collecting the sol, the sol in the collection container 42B was stirred (150 rpm) by the stirring unit 44. The temperature of the sol Z in the collection container 42B (hereinafter referred to as "temperature T4") was measured and found to be 26.8°C.

[0231] The sol in the recovery container 42B was supplied to a gel formation container 411B housed in a temperature-controlled chamber 412B by a sol supply unit 43B. A molding mold (length 20 mm, diameter 5.7 mm) was installed in the gel formation container 411B. The temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 30.0°C. The gel formation container 411B was left standing in the temperature-controlled chamber 412B for 2 hours, and the temperature of the sol in the gel formation container 411B was controlled by the temperature-controlled gas G in the temperature-controlled chamber 412B to prepare a polysiloxane gel. The temperature of the sol after temperature control by the temperature-controlled chamber 412B (hereinafter referred to as the "gelation temperature T2") was measured and found to be 29.9°C.

[0232] (4) Preparation of Silica Monolith The obtained polysiloxane gel was placed in a 5000 mL flask, and 1250 mL of 3 M urea water was added. The mixture was heated to reflux at 95°C for 12 hours. After refluxing, the obtained polysiloxane gel was washed with water and dried for 24 hours in a dryer set at 80°C. After drying, the mixture was fired in an air atmosphere at 600°C for 5 hours to prepare a silica monolith.

[0233] The temperatures T1a, T1b, T3, T4 and gelling temperature T2 in Example 1 are shown in Table 1.

[0234] Example 2 The same operation as in Example 1 was carried out, except that the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 36.3° C. The temperatures T1a, T1b, T3, T4, and gelation temperature T2 in Example 2 are shown in Table 1.

[0235] Example 3 The same operation as in Example 1 was carried out, except that heated water at 23.0° C. was used as the temperature control medium 32 of the temperature control unit 30A, and the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 30.1° C. The temperatures T1a, T1b, T3, T4, and gelation temperature T2 in Example 3 are shown in Table 1.

[0236] Example 4 The same operation as in Example 1 was carried out, except that heated water at 26.0° C. was used as the temperature control medium 32 of the temperature control unit 30A, and the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 25.0° C. The temperatures T1a, T1b, T3, T4, and gelation temperature T2 in Example 4 are shown in Table 1.

[0237] Example 5 The same operation as in Example 1 was carried out, except that the amount of polyethylene glycol 10000 used as the macropore-forming agent was increased by 10% by mass, and the temperature of the temperature-controlled gas G in the thermostatic chamber 412B was set to 31.4° C. The temperatures T1a, T1b, T3, T4, and gelation temperature T2 in Example 5 are shown in Table 1.

[0238] Example 6 The same operation as in Example 1 was carried out, except that the amount of polyethylene glycol 10000 used as the macropore-forming agent was increased by 20% by mass, and the temperature of the temperature-controlled gas G in the thermostatic chamber 412B was set to 30.2° C. The temperatures T1a, T1b, T3, T4, and gelation temperature T2 in Example 6 are shown in Table 1.

[0239] Example 7 The same operation as in Example 1 was carried out, except that the amount of polyethylene glycol 10000 used as the macropore-forming agent was reduced by 5% by mass, and the temperature of the temperature-controlled gas G in the thermostatic chamber 412B was set to 30.5° C. The temperatures T1a, T1b, T3, T4, and gelation temperature T2 in Example 7 are shown in Table 1.

[0240] Comparative Example 1 The same operations as in Example 1 were performed, except that when the sol produced in the sol production unit 10A was supplied to the gel production unit 40B through the sol supply pipe 20, the temperature of the sol flowing through the sol supply pipe 20 was not controlled by the temperature control unit 30A, and the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 25.7° C. The temperatures T1a, T1b, T4, and gelation temperature T2 in Comparative Example 1 are shown in Table 1.

[0241] Comparative Example 2 The same operations as in Example 1 were performed, except that when the sol produced in the sol production unit 10A was supplied to the gel production unit 40B through the sol supply pipe 20, the temperature of the sol flowing through the sol supply pipe 20 was not controlled by the temperature control unit 30A, and the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 29.3° C. The temperatures T1a, T1b, T4, and gelation temperature T2 in Comparative Example 2 are shown in Table 1.

[0242] Comparative Example 3 The same operations as in Example 1 were performed, except that when the sol produced in the sol production unit 10A was supplied to the gel production unit 40B through the sol supply pipe 20, the temperature of the sol flowing through the sol supply pipe 20 was not controlled by the temperature control unit 30A, and the temperature of the temperature-controlled gas G in the temperature-controlled chamber 412B was set to 39.1° C. The temperatures T1a, T1b, T4, and gelation temperature T2 in Comparative Example 3 are shown in Table 1.

[0243]

[0244] <Observation by Scanning Electron Microscope> The surface structures of the silica monoliths of Examples 1 to 7 and Comparative Examples 1 to 3 were observed using a tabletop microscope (SEM) (TM4000II Miniscope, manufactured by Hitachi High-Technologies Corporation). SEM images are shown in Figures 8 and 9. As shown in Figure 9, in the silica monoliths of Comparative Examples 1 to 3, spherical bodies were mixed in the co-continuous structure of the silica skeleton and macropores. This means that in Comparative Examples 1 to 3, homogeneous gels were not produced. In contrast, as shown in Figure 8, in the silica monoliths of Examples 1 to 7, spherical bodies were not mixed in the co-continuous structure of the silica skeleton and macropores. This means that homogeneous gels were produced in Examples 1 to 7.

[0245] DESCRIPTION OF SYMBOLS 1... Gel manufacturing apparatus 10... Sol manufacturing section 20... Sol supply pipe 30... Temperature control section 40... Gel manufacturing section

Claims

1. A gel manufacturing apparatus for manufacturing a gel used in manufacturing a porous silica body having macropores, the gel manufacturing apparatus comprising: a sol manufacturing unit; a gel manufacturing unit; a sol supply pipe for supplying the sol manufactured in the sol manufacturing unit to the gel manufacturing unit; and a temperature control unit for controlling the temperature of the sol flowing through the sol supply pipe, wherein the sol manufacturing unit manufactures a sol at a temperature T1 from a mixed liquid containing a silica precursor, a catalyst, and a macropore-forming agent, the gel manufacturing unit manufactures a gel by controlling the temperature of the sol supplied by the sol supply pipe to a gelation temperature T2, and the temperature control unit controls the temperature of the sol flowing through the sol supply pipe to a temperature T3 that is higher than temperature T1 and lower than gelation temperature T2.

2. The gel manufacturing apparatus according to claim 1, wherein the temperature control section controls the temperature of the sol flowing through the sol supply pipe for 5 seconds or more.

3. A gel manufacturing apparatus according to claim 1 or 2, wherein the temperature T3 is 19.0°C or higher and 27.1°C or lower.

4. A gel manufacturing apparatus according to claim 1 or 2, wherein the difference between temperature T3 and temperature T1 is 1.0°C or more, and the difference between gelation temperature T2 and temperature T3 is 0.1°C or more.

5. A gel manufacturing apparatus as described in claim 1 or 2, wherein the gel manufacturing unit comprises: a gel formation container that contains the sol supplied by the sol supply pipe; and a temperature-controlled chamber that contains the gel formation container and controls the temperature of the sol in the gel formation container to a gelation temperature T2.

6. The gel manufacturing apparatus according to claim 5, wherein the temperature of the sol in the gel forming vessel is controlled only by the temperature-regulating gas in the thermostatic chamber.

7. A gel manufacturing apparatus according to claim 1 or 2, wherein the sol manufacturing unit comprises: a mixing unit that prepares a mixed solution containing the silica precursor, the catalyst, and the macropore-forming agent; a first supply unit that supplies the silica precursor to the mixing unit; a second supply unit that supplies the catalyst and the macropore-forming agent to the mixing unit in a mixed state or separately; a discharge pipe that discharges the mixed solution from the mixing unit; and a temperature control unit that controls the temperature of the mixed solution flowing through the discharge pipe to a predetermined temperature.

8. A method for producing a gel used in producing a porous silica body having macropores, the method comprising the following steps: (1) producing a sol at a temperature T1 from a mixed solution containing a silica precursor, a catalyst, and a macropore-forming agent; (2) supplying the sol produced in step (1) to a gel production section through a sol supply pipe; and (3) producing a gel in the gel production section by controlling the temperature of the sol supplied through the sol supply pipe to a gelation temperature T2, wherein in step (2), the temperature of the sol flowing through the sol supply pipe is controlled to a temperature T3 that is higher than temperature T1 and lower than gelation temperature T2.

Images