Porous material for purifying alcohol, molded body using same, filter for purifying alcohol, and method for purifying alcohol for beverage

Abstract

One aspect of the present invention relates to a porous material that satisfies at least one of a mesopore volume of 0.550 cm3 / g or less or a micropore volume of 1.00 cm3 / g or more, and has a BET specific surface area of 500 m2 / g or more.

Description

Porous material for alcohol purification, molded body using the same, filter for alcohol purification, and method for purifying alcohol for drinking

[0001] The present invention relates to a porous material for alcohol purification, a molded body using the same, a filter for alcohol purification, and a method for purifying alcohol for beverages.

[0002] Various types of beverage alcohol, such as beer and sake, are usually produced through a purification process in which impurities generated during fermentation and organic pigments that cause coloring are adsorbed and removed during the production process. It is known that porous materials, such as activated carbon, are used as adsorbents in this purification process.

[0003] For example, Patent Document 1 reports a method for producing brewed alcoholic beverages from non-malt raw materials, characterized in that activated carbon with an average pore diameter of 1.5 to 2.3 nm is used as an adsorbent to selectively adsorb and remove purine compounds.

[0004] Porous materials with fine pores, such as the activated carbon described in Patent Document 1, have the problem of unintentionally adsorbing substances (e.g., toluene) present in the air during storage and / or transportation before use in alcohol purification. Because the adsorbed substances unintentionally contained in the porous material are likely to dissolve in alcohol, when the porous material is used for purification, there is a risk that the impurities will be released into the drinking alcohol being purified. However, sufficient research has not been conducted to date on means for solving this problem, including the technology described in Patent Document 1.

[0005] Therefore, in view of the above-mentioned current situation, the main object of the present invention is to provide a porous material for alcohol purification, which is capable of suppressing the release of adsorbed substances that have been unintentionally adsorbed before use, etc., and a molded body or purification filter using the same.

[0006] Japanese Patent Application Laid-Open No. 2004-113189

[0007] As a result of intensive research to solve the above problems, the present inventors have found that the above problems can be solved by a porous material having the following configuration, and have completed the present invention through further research based on this finding.

[0008] That is, the porous material according to the first aspect of the present invention has a mesopore volume of 0.550 cm ３ / g or less, or a micropore volume of 1.00 cm ３ / g or more, and the BET specific surface area is 500 m ２ / g or more.

[0009] Fig. 1 is a perspective view of a mold for preparing a molded body of the adsorption filter of this embodiment. Fig. 2 is a schematic diagram showing an automatic grinding machine used in the examples to manufacture the molded body.

[0010] Hereinafter, embodiments of the present invention will be specifically described, but the present invention is not limited to these.

[0011] (Porous Material) Porous Material The porous material of this embodiment, as well as a molded body and a filter containing the porous material as described below, are used in alcohol purification. In this embodiment, alcohol mainly refers to beverage alcohol, and the porous material of this embodiment is particularly suitable for use as an adsorbent for adsorbing and removing impurities (such as organic pigments) from fermented alcohol. Specific examples of fermented alcohol include beer, sake, wine, whiskey, and shochu.

[0012] Specific examples of impurities that can be adsorbed and removed by the porous material of this embodiment include pigments, odorous components, lipids, purine compounds, and the like.

[0013] The porous material of this embodiment has a mesopore volume of 0.550 cm ３ / g or less, or a micropore volume of 1.00 cm ３ / g or more, and the BET specific surface area is 500 m ２By virtue of this constitution, the porous material has the excellent advantage of being able to adsorb and remove impurities in the above-described alcohol purification, while being less likely to release the adsorbed substances into the alcohol before use.

[0014] Therefore, according to the present invention, it is possible to provide a porous material for alcohol purification in which the release of adsorbed substances that have been adsorbed before use or the like is suppressed, a molded body or purification filter using the same, and a method for purifying alcohol for drinking.

[0015] The porous material of this embodiment has a thickness of at least 500 m ２ The specific surface area is determined by the formation of pores in the porous material for adsorbing substances, and is 500 m ２ By having a specific surface area of ​​1000 m / g or more, the porous material can sufficiently adsorb the above-mentioned impurities during alcohol purification. On the other hand, there is no particular upper limit on the specific surface area, but an excessively large specific surface area is not preferred because it reduces the mechanical strength of the porous material. From the viewpoint of simultaneously achieving high adsorption performance during alcohol purification and suppressing the generation of fine powder caused by pulverization of the porous material during purification, the specific surface area is set to 600 to 3500 m. ２ / g, and 750 to 2500m ２ More preferably, it is 500 m / g. ２ / g, 750m ２ / g, 1000m ２ / g, 1250m ２ / g, 1500m ２ / g, 1750m ２ / g, 2000m ２ / g, 2250m ２ / g, 2500m ２ / g, 2750m ２ / g, 3000m ２ / g, 3250m ２ / g, 3500m ２ / g, etc.

[0016] In this embodiment, the BET specific surface area refers to the specific surface area calculated by the nitrogen adsorption method, and is a value measured by the method described in the examples below.

[0017] Pores in porous materials can be classified according to their diameter into micropores (diameter less than 2 nm), mesopores (diameter 2 to 50 nm), and macropores (diameter greater than 50 nm) (the numbers in parentheses indicate the IUPAC classification criteria). In addition to the specific surface area, the porous material of this embodiment has a mesopore volume of 0.550 cm. ３ / g or less, or the micropore volume is 1.00 cm ３ / g or more. By providing such a configuration, it is possible to suppress desorption of impurities that have unintentionally been adsorbed on the porous material before use, and to suppress their release into alcohol.

[0018] From the viewpoint of further suppressing the desorption of impurities, the mesopore volume of the porous material is 0.010 to 0.500 cm ３ / g, and preferably in the range of 0.010 to 0.450 cm ３ From the same viewpoint, the micropore volume of the porous material is more preferably in the range of 1.00 to 4.00 cm 3 / g. ３ / g, and 1.10 to 3.50 cm ３ It is more preferable that the range is / g.

[0019] The porous material of this embodiment only needs to satisfy at least one of the mesopore volume and the micropore volume. The reason for this is believed to be as follows: Because adsorbates adsorbed in mesopores are easily released, a smaller mesopore volume is preferable, while because adsorbates adsorbed in micropores are difficult to release, a larger micropore volume is preferable. Since mesopores and micropores each independently contribute to the desorption of impurities, it is believed that satisfying at least one of the mesopore volume and the micropore volume can suppress the desorption of impurities. Naturally, the porous material of this embodiment may satisfy both the mesopore volume and the micropore volume.

[0020] The mesopore volume of a porous material can be calculated from a nitrogen adsorption isotherm using the BJH (Barrett-Joyner-Halenda) method. Furthermore, the micropore volume can be calculated from the nitrogen adsorption isotherm using the MP method. Specific measurements of the nitrogen adsorption isotherm and calculations of the mesopore volume and micropore volume can be performed by the methods described in the "Measurement of Nitrogen Adsorption Isotherm," "Measurement of Mesopore Volume by the BJH Method," and "Measurement of Micropore Volume by the MP Method" sections in the Examples below.

[0021] In this specification, examples of unintended adsorbed substances that are unintentionally adsorbed onto porous materials include, but are not limited to, substances present in the atmosphere, such as toluene, benzene, formaldehyde, hexane, and phenol.

[0022] The porous material of this embodiment preferably has an acidic functional group content of 0.700 meq / g or less. A low acidic functional group content improves the hydrophobicity of the porous material, allowing it to more strongly adsorb organic substances. This effectively inhibits the desorption of unintended adsorbed substances adsorbed to the porous material, further reducing the elution of impurities into alcohol. Furthermore, the amount of adsorbed impurities during alcohol purification is thought to increase.

[0023] The lower limit of the amount of acidic functional groups is not particularly limited as long as it is 0.700 meq / g or less, but from the viewpoint of increasing affinity with the adsorbent, it is more preferably 0.010 to 0.600 meq / g, even more preferably 0.020 to 0.500 meq / g, and particularly preferably 0.030 to 0.400 meq / g.

[0024] In this embodiment, the "amount of acidic functional groups in the porous material" is a value measured by the method described in the examples below.

[0025] The porous material of this embodiment preferably has a toluene adsorption capacity of approximately 10 to 80% by weight. In this embodiment, the "toluene adsorption capacity" is used as an index of the organic substance adsorption capacity of the porous material. The toluene adsorption capacity of the porous material can be measured by the method described in the Examples below.

[0026] The porous material of this embodiment preferably has a methylene blue adsorption capacity of approximately 50 to 400 mg / g. In this embodiment, the "methylene blue adsorption capacity" is used as an index of alcohol purification performance (the ability to remove dyes contained in alcohol). The methylene blue adsorption capacity of the porous material can be measured by the method described in the Examples below.

[0027] Porous materials that can be used in this embodiment include activated carbon, silica gel, zeolite, and diatomaceous earth. Of these, activated carbon is most preferably used as the porous material because of its high ability to adsorb organic substances.

[0028] Activated Carbon The activated carbon preferably used in this embodiment may be any activated carbon obtained from any carbonaceous material as long as it can be turned into activated carbon by carbonizing and activating the carbonaceous material.

[0029] In this embodiment, the activated carbon may be any one selected from powdered activated carbon, fibrous activated carbon, granular activated carbon, and pelleted activated carbon. Fibrous activated carbon is activated carbon obtained by carbonizing and activating appropriate fibers, and examples thereof include phenolic resin-based, acrylic resin-based, cellulose-based, and coal pitch-based activated carbons. The fiber length, cross-sectional diameter, and the like can be appropriately set.

[0030] Raw materials for granular activated carbon include wood (waste wood, thinned wood, sawdust), coffee grounds, rice husks, coconut shells, bark, and fruit kernels. These naturally derived raw materials are more likely to develop pores when carbonized and activated. Furthermore, because they are secondary waste materials, they can be procured inexpensively. Other materials that can be used include burned materials derived from tires, petroleum pitch, urethane resin, phenolic resin, and other synthetic resins, as well as coal.

[0031] Among these, the activated carbon of the present embodiment is preferably in the form of a powder, granules, or pellets. Powdered activated carbon and pelleted activated carbon can be produced by pulverizing or molding the above-mentioned fibrous or granular activated carbon.

[0032] In a preferred embodiment, granular or powdered activated carbon with an average particle size in the range of 10 to 500 μm is used, which has the advantage of shortening the filtration time of the adsorbent after adsorption and shortening the adsorption time. A more preferred average particle size is 50 to 300 μm.

[0033] The activated carbon used in this embodiment may be one type used alone or two or more types used in combination.

[0034] -Method for Producing Activated Carbon The method for producing the porous material of this embodiment will be described in detail using activated carbon as a specific example.

[0035] The activated carbon of the present embodiment can be obtained, for example, by dry distilling and / or carbonizing the above-described carbonaceous material depending on the type of material and as necessary, and then subjecting the material to activation treatment in an atmosphere of a mixed gas containing water vapor, nitrogen, and carbon dioxide.

[0036] For example, when the carbonaceous material is bituminous coal, it is preferable to perform a carbonization treatment before the activation treatment. Conventional means can be used for the carbonization treatment, and the carbonization treatment can usually be performed at a temperature of about 400 to 800°C while blocking oxygen or air.

[0037] Furthermore, when the carbonaceous material is coconut shell, palm shell, wood, etc., it is preferable to carry out a carbonization treatment before the activation treatment. When carrying out the carbonization treatment, a conventional means can be used, and the carbonization treatment is usually carried out in a state where oxygen or air is blocked, for example, at a temperature of about 400 to 800°C.

[0038] As a method for activating the above-mentioned carbonaceous material or its dry distillate or carbonized product, either a gas activation method or a chemical activation method can be used, and a combination of the gas activation method and the chemical activation method may also be used.

[0039] When gas activation is performed, the carbonaceous material can be exposed to water vapor, carbon dioxide gas, or a mixed gas thereof in a temperature range of 600°C to 1200°C using a fluidized bed, multi-stage furnace, rotary furnace, or other common activated carbon manufacturing equipment. The activation temperature may preferably be 600°C or higher but lower than 1000°C. In consideration of safety and reactivity, it is preferable to use a water vapor-containing gas containing 10 to 40% by volume of water vapor as the activation gas. The activation time and temperature rise rate are not particularly limited and can be selected appropriately depending on the type, shape, and size of the carbonaceous material selected.

[0040] Chemical activation is carried out by mixing an activator such as zinc chloride, calcium chloride, phosphoric acid, sulfuric acid, sodium hydroxide, potassium hydroxide, magnesium hydroxide, or calcium hydroxide with the carbonaceous material and heating the mixture in an inert gas atmosphere. The heating temperature is about 400 to 700°C. The heating time, etc., are not particularly limited and can be selected appropriately depending on the type, shape, and size of the carbonaceous material selected.

[0041] The activated carbon after activation treatment may be washed with a washing solution containing an acid to remove impurities such as metal components contained in the activated carbon. Acid washing can be performed, for example, by immersing the activated carbon in a washing solution containing an acid. In the acid washing step, the raw activated carbon may be washed with hydrochloric acid and then washed with water, or an appropriate combination of water washing and acid washing may be used, such as by repeatedly performing acid washing and water washing. The acid washing solution preferably includes inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid, and organic acids such as saturated carboxylic acids such as formic acid, acetic acid, propionic acid, oxalic acid, tartaric acid, and citric acid, and aromatic carboxylic acids such as benzoic acid and terephthalic acid. Among these, washing with hydrochloric acid is more preferred. When hydrochloric acid is used as the acid washing solution, it is preferable to use dilute hydrochloric acid.

[0042] The activated carbon obtained may be pulverized with a roll mill or the like, and then subjected to dry classification, if necessary, to adjust the average particle size.

[0043] (Molded body) The molded body of this embodiment includes the porous material and a binder as described above. The binder used in this embodiment is not particularly limited as long as it can be molded by entangling the porous material, but is preferably a fibrous binder.

[0044] A wide variety of fibrous binders, both synthetic and natural, can be used in this embodiment. Specific binders include, for example, acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, aramid fibers, and pulp. The fiber length of the fibrous binder is preferably 4 mm or less. Among these, it is preferable to use acrylic fibrous binders, etc., from the viewpoints of alcohol resistance, heat resistance, and high strength retention. Two or more of the above fibrous binders may be used in combination.

[0045] In this embodiment, the water permeability of the fibrous binder is preferably about 10 to 150 mL in terms of CSF value. More preferably, it is about 20 to 110 mL. In this embodiment, the CSF value is a value measured in accordance with JIS P8121 (2012) "Testing Method for Pulp Freeness," the Canadian Standard Freeness Method. The CSF value can be adjusted, for example, by fibrillating the binder.

[0046] The molded body of this embodiment preferably has an acidic functional group content of 0.800 meq / g or less when measured by cutting out a portion. The low acidic functional group content improves the hydrophobicity of the molded body, allowing for stronger adsorption of organic substances. This can further suppress desorption of unintended adsorbed substances adsorbed to the porous material contained in the molded body, thereby further reducing the elution of the impurities into alcohol. Furthermore, it is believed that the amount of adsorption of impurities during alcohol purification increases.

[0047] The lower limit of the amount of acidic functional groups is not particularly limited as long as it is 0.800 meq / g or less. However, from the viewpoint of increasing affinity with the adsorbate, the amount is more preferably 0.010 to 0.750 meq / g, and even more preferably 0.020 to 0.700 meq / g.

[0048] In this embodiment, the "amount of acidic functional groups in the molded body" is a value measured by the method described in the examples below.

[0049] - Manufacturing method of molded body The molded body of this embodiment is obtained by a manufacturing method including a slurry preparation step of mixing a porous carbon material and a binder to obtain a mixture and dispersing the mixture in water to prepare a slurry, a suction filtration step of filtering the slurry while suctioning to obtain a premolded body, and a drying step of drying the premolded body to obtain a dried molded body.

[0050] The slurry can be prepared, for example, by dispersing a granular or powdered porous carbon material and a fibrous binder in water to a solids concentration of 1 to 15 wt %. If the solids concentration of the slurry is too high, the dispersion is likely to become non-uniform, and the molded body is likely to have spots. On the other hand, if the solids concentration is too low, not only will the molding time be extended and productivity will decrease, but the density of the molded body will increase, making it more likely to become clogged due to the capture of turbid components.

[0051] In the suction filtration step, for example, the slurry is placed in a molding frame having a large number of holes, and the slurry is filtered while being suctioned from the inside of the frame. A conventional molding frame can be used as the molding frame, such as a cylindrical molding frame 1 having a large number of small suction holes 3 on the surface of a core body 2 and flanges 4, 4' attached to both ends, as shown in Figure 1. A conventional suction method can also be used, such as a method of suction using a suction pump. After suction filtration, the preform may be compressed on a shaping table to shape the outer surface.

[0052] In the drying step, the preform obtained in the suction filtration step is removed from the mold and dried in a dryer or the like to obtain a molded body. The drying temperature is, for example, about 100 to 150°C (particularly 110 to 130°C), and the drying time is, for example, about 4 to 24 hours (particularly 8 to 16 hours). If the drying temperature is too high, the fibrous binder may be altered or melted, resulting in a decrease in filtration performance and a decrease in the strength of the molded body. If the drying temperature is too low, the drying time may be long or the drying may be insufficient. In addition, a step of grinding (or polishing) the outer surface of the dried molded body may be performed. Grinding can be performed appropriately to obtain the desired size using a known automatic grinding machine (e.g., the grinding machine shown in Figure 2).

[0053] (Alcohol Purification Filter) This embodiment includes a filter for alcohol purification comprising the porous material described above. The filter for alcohol purification of this embodiment (hereinafter also simply referred to as "filter") is not particularly limited as long as it comprises the porous material described above, but for example, a molded body containing the porous material and a binder can be used as the alcohol purification filter.

[0054] The filter of the embodiment may contain functional components other than those described above, as long as the effects of the present invention are not impaired. For example, an additive such as zeolite may be added in any amount to remove heavy metals from the liquid. In this case, the amount of the additive is usually 0.1 to 30 parts by mass based on the total mass of the filter.

[0055] When the molded article described above is used as a filter, the mixing ratio of each component in the filter of this embodiment is preferably about 1 to 10 parts by mass of the binder per 100 parts by mass of the porous material or the mixture of the porous material and the functional component, from the viewpoints of adsorption effect, moldability, etc. If the amount of binder is less than 1 part by mass, sufficient strength may not be obtained, and the molded article may not be able to be molded. Furthermore, if the amount of binder exceeds 10 parts by mass, adsorption performance may be reduced. More preferably, the fibrous binder is blended in an amount of 3 to 8 parts by mass, and even more preferably, the fibrous binder is blended in an amount of 3.5 to 6 parts by mass.

[0056] The filter of this embodiment may be a cylindrical filter that further includes a core in addition to the molded body. The cylindrical shape reduces water flow resistance and, when used as a cartridge by filling a housing as described below, simplifies the loading and replacement of the cartridge into a water purifier.

[0057] The core that can be used in this embodiment is not particularly limited as long as it can be inserted into the hollow part of the cylindrical filter and can reinforce the cylindrical filter, but for example, a toric pipe, a netron pipe, or a ceramic filter is preferable. A nonwoven fabric or the like can be wrapped around the outer periphery of the core, or a porous filter made by melt-blown polypropylene resin can also be used.

[0058] As described above, the filter of this embodiment is useful as a filter for alcohol purification. The form of use of the filter of this embodiment is not particularly limited, and the filter can be filled into a housing and used as a cartridge for alcohol purification.

[0059] This specification discloses various aspects of the technology as described above, but the main technologies among them are summarized below.

[0060] That is, the porous material according to the first aspect of the present invention has a mesopore volume of 0.550 cm ３ / g or less, or a micropore volume of 1.00 cm ３ / g or more, and the BET specific surface area is 500 m ２ / g or more.

[0061] A porous material according to a second aspect of the present invention is the porous material for alcohol purification according to the first aspect, in which the amount of acidic functional groups is 0.700 meq / g or less.

[0062] A porous material according to a third aspect of the present invention is the porous material for alcohol purification according to the first or second aspect, characterized in that it is activated carbon.

[0063] A molded article according to a fourth aspect of the present invention comprises the porous material for alcohol purification according to any one of the first to third aspects and a binder.

[0064] A molded article according to a fifth aspect of the present invention is the molded article according to the fourth aspect, in which the amount of acidic functional groups measured by cutting out a part of the molded article is 0.800 meq / g or less.

[0065] A filter for alcohol purification according to a sixth aspect of the present invention comprises the porous material for alcohol purification according to any one of the first to third aspects, or the molded article according to the fourth or fifth aspect.

[0066] A method for purifying drinking alcohol according to a seventh aspect of the present invention comprises removing impurities contained in fermented alcohol by adsorbing them onto the porous material for alcohol purification according to any one of the first to third aspects.

[0067] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0068] First, the test methods for evaluating the properties in the present example will be described.

[0069] [Measurement of Nitrogen Adsorption Isotherm] Using a BELSORP-MAX II manufactured by Microtrac-Bell Corporation, the carbonaceous material was heated at 300°C under reduced pressure (vacuum degree: 0.1 kPa or less) for 3 hours, and then the nitrogen adsorption isotherm of each porous material at 77K was measured.

[0070] [Measurement of BET Specific Surface Area] The nitrogen adsorption isotherm obtained by the above method was analyzed by the multipoint method using the BET equation, and the specific surface area was calculated from the straight line in the region of the relative pressure P / P0 = 0.01 to 0.1 of the obtained curve.

[0071] [Measurement of Mesopore Volume (BJH Method)] The nitrogen adsorption isotherm was analyzed by the BJH method. The analysis conditions were an adsorbate molecular weight of 28.013 and an adsorbate density of 0.808 g / cm. ３ The file data was interpolated linearly. The resulting adsorption isotherm was analyzed by the BJH method using data for (p / p) values ​​between 0.10 and 0.99, and the pore volumes for diameters from 2 nm to 50 nm were calculated.

[0072] [Measurement of Micropore Volume (MP Method)] The nitrogen adsorption isotherm was analyzed by the MP method to calculate the volume of pores with a diameter of 3.5 nm or less. For the analysis by the MP method, the standard curve "NGCB-BEL.t" provided by Microtrac-BEL Co., Ltd. was used.

[0073] [Measurement of the amount of acidic functional groups] The porous material was finely pulverized until the particle size distribution was 2 mm or less, and the molded body was measured by scraping off a part of the porous material layer (the layer between the outer diameter side and the center of the inner diameter of the cylindrical molded body) with a cutter knife, and the scraped off material was finely pulverized until the particle size distribution was 2 mm or less, and then used for measurement.

[0074] The crushed porous material and crushed molded body were each dried at 115°C for 3 hours, then allowed to cool to room temperature in a desiccator using silica gel as a desiccant. 1.0 g of the resulting mixture was used as a measurement sample. The measurement sample was added to 50 mL of 0.1 mol / L sodium hydroxide solution as an alkaline solution, shaken for 30 minutes, and then allowed to stand at 25°C for 24 hours. The solution was then centrifuged, and 10 mL of the supernatant was collected and subjected to neutralization titration with 0.1 mol / L hydrochloric acid solution to determine the amount of acidic functional groups (meq / g).

[0075] [Toluene Adsorption Performance of Porous Material] The porous material was dried in a thermostatic oven at 115°C for 3 hours and then allowed to cool to room temperature in a desiccator using silica gel as a desiccant. Next, dry air containing toluene at a concentration of 1 / 10 of the saturated concentration was passed through the porous material in an incubator at 25°C. The toluene adsorption amount (wt%) was calculated from the difference between the weight of the porous material when adsorption equilibrium was reached (the weight of the porous material no longer increased) and the weight of the porous material before adsorption using the following formula: Toluene adsorption performance (wt%) = [{(weight of sample after toluene adsorption (g)) - (weight of sample before toluene adsorption (g))} / (weight of sample before toluene adsorption (g))] × 100

[0076] [Methylene blue (dye) adsorption performance of porous material in alcohol solution] To confirm the alcohol purification performance of the porous material, the methylene blue adsorption performance in alcohol solution was measured. The porous material was pulverized in a sample mill to an average particle size of 30 μm or less, dried in a thermostatic oven at 115°C for 3 hours, and then allowed to cool to room temperature in a desiccator using silica gel as a desiccant.

[0077] 0.01 g of this porous material was precisely weighed and added to 0.05 L of a solution prepared by dissolving methylene blue (dye) in a 20 vol% aqueous ethanol solution to a concentration of 120 mg / L, and after stirring at 25°C for 2 hours, the solution was filtered through No. 5C filter paper. The methylene blue concentration (mg / L) in the filtrate was measured at a wavelength of 665 nm using a spectrophotometer, and the amount of methylene blue adsorbed (mg / g) per weight of the porous material was calculated using the following formula: Methylene blue adsorption performance (mg / g) = [{(methylene blue concentration (mg / L) before methylene blue adsorption) - (methylene blue concentration (mg / L) after methylene blue adsorption)} × 0.05 (L) / (sample weight (g) before methylene blue adsorption)]

[0078] [Porous Material] (Example 1) Coconut shell charcoal obtained by carbonizing coconut shells produced in the Philippines was activated with steam at 900°C for 1 hour. The obtained coconut shell activated carbon was washed with dilute hydrochloric acid, desalted with ion-exchanged water, and then dried. The activated carbon was then pulverized in a roll mill and subjected to dry classification to obtain porous material A with an average particle size of 150 μm. The toluene adsorption capacity of porous material A was 27.7%.

[0079] Example 2: Coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was activated with steam at 900°C for 2 hours. The obtained coconut shell activated carbon was washed with dilute hydrochloric acid, desalted with ion-exchanged water, and then dried. It was then pulverized in a roll mill and dry-classified to obtain porous material B with an average particle size of 150 μm. The toluene adsorption capacity of porous material B was 36.6%.

[0080] (Example 3) Coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was activated with steam at 900°C for 3 hours. The obtained coconut shell activated carbon was washed with dilute hydrochloric acid, desalted with ion-exchanged water, and then dried. It was then pulverized in a roll mill and dry-classified to obtain porous material C with an average particle size of 150 μm. The toluene adsorption capacity of porous material C was 51.4%.

[0081] Example 4: Coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was activated with steam at 900°C for 3.3 hours. The obtained coconut shell activated carbon was washed with dilute hydrochloric acid, desalted with ion-exchanged water, dried, pulverized in a roll mill, and then dry-classified to obtain porous material D having an average particle size of 150 µm. The toluene adsorption capacity of porous material D was 53.4%.

[0082] Example 5: Coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was activated with steam at 900°C for 1 hour. 600 g of the resulting raw activated carbon was added to 2120 mL of hydrochloric acid (0.3 N) and washed by boiling for 20 minutes. After that, it was thoroughly washed with ion-exchanged water until the pH reached 5-7. It was then dried in a natural convection constant temperature dryer at 115±5°C for 4 hours to reduce the potassium content in the activated carbon. The raw activated carbon was then contacted with a calcium element source (a calcium nitrate aqueous solution (23 g of calcium nitrate tetrahydrate and 117 g of ion-exchanged water) was sprayed onto 500 g of the resulting activated carbon, followed by drying in a natural convection constant temperature dryer at 115±5°C for 5-7 hours) for further activation. The resulting coconut shell activated carbon was then washed with dilute hydrochloric acid, desalted with ion-exchanged water, and dried. It was then pulverized in a roll mill and dry-classified to obtain a porous material E with an average particle size of 150 μm. The toluene adsorption performance of the porous material E was 71.2%.

[0083] (Example 6) Bituminous coal was used as the carbonaceous raw material and was subjected to a dry distillation treatment at 700°C. Next, a mixed gas of water vapor, carbon dioxide, and nitrogen was introduced into the obtained dry distillation product, and activation was performed at a temperature of 750°C for 5 hours. Thereafter, the product was pulverized in a roll mill and then dry classified to obtain porous material F having an average particle size of 150 μm. The toluene adsorption capacity of porous material F was 38.4%.

[0084] (Example 7) A woody raw material was impregnated with phosphoric acid as a carbonaceous raw material and then activated at 500°C. The activated carbon was then washed with water and dried, and then pulverized in a ball mill to obtain porous material G1 with an average particle size of 30 μm and a toluene adsorption capacity of 45.3%. Additionally, coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was activated with steam at 900°C for 2.5 hours. The coconut shell activated carbon obtained was washed with dilute hydrochloric acid, desalted with ion-exchanged water, and dried. The material was then pulverized in a roll mill and dry-classified to obtain porous material G2 with an average particle size of 150 μm and a toluene adsorption capacity of 45.3%. G1 and G2 were blended at a ratio of 95:5 to obtain porous material G with a toluene adsorption capacity of 45.3%.

[0085] (Example 8) A woody raw material was used as a carbonaceous raw material and steam-activated at 900°C. The resulting activated carbon was pulverized using a roll mill and then dry-classified to obtain porous material H1 with an average particle size of 150 μm and a toluene adsorption capacity of 33.0%. Additionally, coconut shell charcoal obtained by carbonizing coconut shells from the Philippines was steam-activated at 900°C for 1.5 hours. The coconut shell activated carbon obtained was washed with dilute hydrochloric acid, desalted with ion-exchanged water, and then dried. Next, the material was pulverized using a roll mill and then dry-classified to obtain porous material H2 with an average particle size of 150 μm and a toluene adsorption capacity of 33.0%. H1 and H2 were blended at a ratio of 95:5 to obtain porous material H with a toluene adsorption capacity of 33.0%.

[0086] Comparative Example 1: Bituminous coal was used as the carbonaceous raw material and was subjected to a dry distillation treatment at 960°C. A mixed gas of water vapor, carbon dioxide, and nitrogen was then introduced into the dry distillation product, and activation was performed at an activation temperature of 1000°C. The obtained activated carbon was pulverized using a roll mill and then dry classified to obtain Porous Material I with an average particle size of 150 μm. The toluene adsorption capacity of Porous Material I was 57.3%.

[0087] [Production of Molded Body / Filter] A mixture of 100.0 parts by mass of porous material and 5.0 parts by mass of acrylic fibrous binder (manufactured by Nippon Exlan Industrial Co., Ltd., "Acrylic Fiber BiPUL 50TWF", CSF value 83 mL) was prepared to a total weight of 8.36 kg, and tap water was added. The volume of the slurry after the addition was 83.6 L.

[0088] Next, a core was attached to the cylindrical molding frame (outer diameter 40.0 mmφ, center shaft diameter 11.6 mmφ, and outer diameter flange spacing 365.0 mmH) shown in Figure 1, and the resulting slurry was molded to 43 mmφ, slightly larger than the outer diameter of the mold, by suction at 400 mmHg only, and then dried for 16 hours at 120 ° C. The resulting molded body was then attached to the automatic grinding machine shown in Figure 2, and the outer surface of the molded body was ground at a molded body rotation speed of 360 rpm, a grindstone rotation speed of 2535 rpm, and a grindstone movement speed of 250 mm / 10 sec (2.5 cm / sec), to obtain a cylindrical filter with an outer diameter of 38.6 mmφ, an inner diameter of 12 mmφ, and a height of 108.0 mmH.

[0089] In FIG. 2, the reference symbols indicate 11: grinding machine, 12 and 17: rotating shaft, 13: disc-shaped grinding wheel, 14 and 18: motor, 15 and 16: air cylinder, 19: operation panel, and 20: molded body.

[0090] <Evaluation Method> The amount of toluene released from the porous materials A to I of Examples 1 to 8 and Comparative Example 1 was measured to evaluate the suppression of desorption of the adsorbed substances of each material.

[0091] (Measurement of Toluene Release Amount) Measurement of Packing Density (Tap Density) of Porous Material To determine the toluene release amount, first, the packing density of each porous material was measured as follows: After drying the porous material at 115°C for 3 hours, it was allowed to cool to room temperature in a desiccator using silica gel as a desiccant. Thereafter, about 30 ml was poured into a 50 ml measuring cylinder, and after vibrating it up and down for 3 minutes, the volume value was read, the weight of the porous material was measured, and the weight was calculated according to the following formula: Packing density of porous material (g / ml) = (mass (g) of porous material) / (volume (ml) of porous material)

[0092] Amount of toluene released: The porous material was dried in a thermostatic oven at 115°C for 3 hours, and then allowed to cool to room temperature in a desiccator using silica gel as a desiccant. Next, in an incubator at 25°C, dry air containing toluene at a concentration of 1 / 10 of the saturated concentration was passed through the porous material until the toluene adsorption amount reached 1 wt%, yielding a porous material with a toluene adsorption amount of 1 wt%.

[0093] 0.2 g of this porous material was weighed out and immersed in 0.05 L of a 20 vol% aqueous ethanol solution. After stirring at 25°C for 2 hours, the mixture was filtered through No. 5C filter paper. The toluene concentration (mg / L) in the filtrate was measured using a gas chromatograph mass spectrometer (GC-MS). The amount of toluene released per volume of porous material (mg / ml) was calculated using the following formula: Amount of toluene released (mg / ml) = toluene concentration in filtrate (mg / L) × amount of 20 vol% aqueous ethanol solution (0.050 (L)) / amount of porous material adsorbing 1% toluene (0.2 (g)) × packing density of porous material (g / ml).

[0094] In this evaluation, if the amount of toluene released per volume of the porous material obtained above was 0.080 mg / ml or less, the porous material was judged to be acceptable.

[0095] The above results are summarized in Table 1.

[0096]

[0097] (Discussion) As is clear from the results in Table 1, it was found that the release of adsorbed toluene was suppressed in all of the porous materials of the Examples. On the other hand, the porous materials of the Comparative Examples, which did not satisfy the requirements for mesopore volume and micropore volume, released the adsorbed toluene, and therefore are thought to be difficult to use for alcohol purification.

[0098] This application is based on Japanese Patent Application No. 2024-010011 filed on January 26, 2024, the contents of which are incorporated herein by reference.

[0099] In order to express the present invention, the present invention has been properly and sufficiently described above through embodiments with reference to specific examples, drawings, etc., but it should be recognized that those skilled in the art can easily make changes and / or improvements to the above-described embodiments. Therefore, unless changes or improvements made by those skilled in the art deviate from the scope of the claims set forth in the claims, such changes or improvements are construed as being encompassed within the scope of the claims.

[0100] The present invention has wide industrial applicability in the technical fields of alcohol purification and porous materials.

[0101] REFERENCE SIGNS LIST 1 mold 2 core 3 suction hole 4, 4' flange 5 filtrate discharge port 11 grinding machine 12, 17 rotating shaft 13 disc-shaped grinding wheel 14, 18 motor 15, 16 air cylinder 19 operation panel 20 molded body

Claims

1. A porous material for alcohol purification, satisfying at least one of the following conditions: the mesopore volume is 0.550 cm ３ / g or less, or the micropore volume is 1.00 cm ３ / g or more, and having a BET specific surface area of 500 m ２ / g or more.

2. The porous material for alcohol purification according to claim 1, wherein the amount of acidic functional groups is 0.700 meq / g or less.

3. The porous material for alcohol purification according to claim 1, wherein the porous material is activated carbon.

4. A molded body comprising the porous material for alcohol purification according to claim 1 and a binder.

5. The molded body according to claim 4, wherein the amount of acidic functional groups measured by cutting out a part is 0.800 meq / g or less.

6. An alcohol purification filter comprising the porous material for alcohol purification according to claim 1 or the molded body according to claim 4.

7. A method for purifying beverage alcohol, comprising adsorbing and removing impurities contained in fermented alcohol on the porous material for alcohol purification according to claim 1.

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