Porous carbon material, method for producing porous carbon material, method for purifying water or air, and adsorbent

Abstract

The present disclosure provides a porous carbon material that has an average particle size of 10 μm to 200 μm and has a cumulative pore volume of 0.2 cm3 / g to 9 cm3 / g for pores having a pore diameter of 0.0036 μm to 400 μm.

Description

Porous carbon material, method for producing porous carbon material, method for purifying water or air, and adsorbent

[0001] The present disclosure relates to a porous carbon material and a method for producing the same.

[0002] Activated carbon is used in a wide variety of applications, including separation processes, purification, catalysts, solvent recovery, wastewater treatment related to global environmental pollution problems, pollution countermeasures, and medical uses. In recent years, environmental problems have become more serious, and in particular, water pollution has become a major issue. In such a situation, water purification has become an increasingly important need. Activated carbon can effectively remove various pollutants due to its excellent adsorption characteristics. In particular, due to considerations for the environment, the demand for activated carbon using natural materials is increasing.

[0003] Japanese Patent Application Laid-Open No. 5-49923, Japanese Patent Application Laid-Open No. 2007-308325

[0004] As activated carbon, it is preferable to use activated carbon with a small particle size because the specific surface area is improved and the adsorption performance is improved. Also, it is preferable that the particle sizes are uniform because stable performance can be exhibited.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a novel porous carbon material having good adsorption performance and a method for producing the same.

[0006] One embodiment of the present disclosure has an average particle diameter of 10 μm or more and 200 μm or less, and a cumulative pore volume of 0.2 cm ３ / g or more and 9 cm ３ / g or less for pore diameters measured by the mercury intrusion method. A porous carbon material is provided.

[0007] Another embodiment of the present disclosure has an average particle diameter of 10 μm or more and 200 μm or less, and a total pore volume of 0.05 cm ３ / g or more and 1.5 cm ３ / g or less measured by the nitrogen gas adsorption method. A porous carbon material is provided.

[0008] Another embodiment of the present disclosure provides a porous carbon material derived from the frass of the larvae of beetles of the family Tenebrionidae.

[0009] Other embodiments of the present disclosure provide a method for producing a porous carbon material, comprising a carbonization step of carbonizing the frass of an insect larva.

[0010] Other embodiments of this disclosure provide a method for purifying water or air using the porous carbon material described above.

[0011] Other embodiments of this disclosure provide an adsorbent comprising the porous carbon material described above.

[0012] This disclosure offers the advantage of providing a novel porous carbon material having good adsorption performance and a method for producing the same.

[0013] This is an SEM image of the porous carbon material from Example 1. This is an SEM image of the frass of the larva of a Tenebrionidae beetle used in Example 1.

[0014] Embodiments of this disclosure will be described below with reference to drawings and other figures. However, this disclosure can be implemented in many different ways and should not be interpreted as being limited to the embodiments described below. In addition, the drawings may be schematically represented in terms of width, thickness, shape, etc. of each part compared to the actual form in order to make the explanation clearer, but these are merely examples and should not limit the interpretation of this disclosure. Furthermore, in this specification and each figure, elements similar to those described above with respect to previously shown figures will be denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0015] The porous carbon material, the method for producing the porous carbon material, the method for purifying water or air, and the adsorbent described herein will be explained in detail below.

[0016] A. Porous Carbon Materials The porous carbon materials in this disclosure have three embodiments. Each embodiment will be described below.

[0017] A1. First Embodiment of Porous Carbon Material The first embodiment of the porous carbon material in this disclosure has an average particle diameter of 10 μm or more and 200 μm or less, and a cumulative pore volume of 0.2 cm³ with a pore diameter of 0.0036 μm or more and 400 μm or less, as measured by the mercury intrusion method. ３ / g or more 9cm ３ It is less than or equal to / g.

[0018] In this embodiment, the cumulative pore volume for pores with a diameter of 0.0036 μm or more and 400 μm or less, as measured by the mercury intrusion method, is within a predetermined range, so the pore depth is considered to be relatively large. Therefore, high adsorption performance can be achieved.

[0019] In this specification, "porous carbon material" refers to a porous material mainly composed of carbon material. Examples of porous carbon materials include activated carbon. Furthermore, the porous carbon material may be unactivated carbide, as long as it satisfies the requirements of this disclosure.

[0020] The following describes the structure of the porous carbon material in this embodiment.

[0021] In one embodiment of this disclosure, at least one element selected from the group consisting of magnesium (Mg), phosphorus (P), and potassium (K) is detected on the surface of the porous carbon material by energy-dispersive X-ray analysis (hereinafter referred to as "EDX"). As described in the Examples section below, in the comparative example activated carbon, none of the elements Mg, P, and K were detected on the surface of the activated carbon by EDX. Therefore, the porous carbon material in this embodiment is a novel porous carbon material. Furthermore, the presence of the above elements on the surface of the porous carbon material is expected to contribute to chemiadsorption.

[0022] In particular, on the surface of porous carbon materials, it is preferable that two or more elements selected from the group consisting of Mg, P, and K are detected by EDX, and it is more preferable that all elements of Mg, P, and K are detected.

[0023] Furthermore, even if at least one element selected from the group consisting of Mg, P, and K is detected by an analytical method other than EDX, cases where Mg, P, and K are not detected by EDX on the surface of the porous carbon material are not included in this embodiment.

[0024] The measurement conditions of EDX are shown below. <Measurement Conditions> - Apparatus: Scanning electron microscope equipped with an energy-dispersive X-ray analyzer (SEM-EDX) - Acceleration voltage: 15 kV - SEM aperture: 80 μm - Sample tilt: 0° - Working distance (WD): 10 mm

[0025] Regarding the composition on the surface of the porous carbon material, for example, by appropriately selecting the raw material of the porous carbon material, the composition on the surface of the porous carbon material can be adjusted. When using the frass of insect larvae as the raw material of the porous carbon material as described later, by appropriately selecting the food of the insect larvae, the composition on the surface of the porous carbon material can be adjusted.

[0026] The cumulative volume of pores with a pore diameter of 0.0036 μm or more and 400 μm or less in the porous carbon material measured by the mercury intrusion method is 0.2 cm ３ / g or more, preferably 1 cm ３ / g or more, and more preferably 2 cm ３ / g or more. By having the cumulative pore volume within the above range, high adsorption performance can be exhibited. On the other hand, the cumulative pore volume is 9 cm ３ / g or less, may be 7 cm ３ / g or less, and may also be 5 cm ３ / g or less. If the cumulative pore volume becomes too large, there is a risk that the specific surface area will decrease. Specifically, the cumulative pore volume is 0.2 cm ３ / g or more and 9 cm ３ / g or less, may be 1 cm ３ / g or more and 7 cm ３ / g or less, and may also be 2 cm ３ / g or more and 5 cm ３ / g or less. The cumulative pore volume is a value measured by the mercury intrusion method using a fully automatic pore distribution measuring device as described later. The cumulative pore volume is the cumulative pore volume with a pore diameter of 0.0036 μm or more and 400 μm or less, that is, the sum of the volumes of pores having a pore diameter of 0.0036 μm or more and 400 μm or less.

[0027] The cumulative pore volume of porous carbon materials can be adjusted, for example, by appropriately selecting the raw materials for the porous carbon material or by appropriately adjusting the manufacturing conditions of the porous carbon material. When beetle larval frass is used as the raw material for the porous carbon material, as described later, the cumulative pore volume of the porous carbon material tends to be large. Furthermore, when insect larval frass is used as the raw material for the porous carbon material, the cumulative pore volume of the porous carbon material can be made relatively large by adjusting the activation temperature.

[0028] The specific surface area of ​​a porous carbon material is, for example, 39 m². ２ Preferably 40 m ２ More preferably 80 m ２ A value of 1 / g or more is more preferable. A specific surface area within the above range allows for high adsorption performance. On the other hand, the specific surface area of ​​a porous carbon material is, for example, 200 m². ２ It is less than / g and 150m ２ It may be less than / g. If the specific surface area becomes too large, the density will decrease, and there is a risk that the strength will decrease. Specifically, the specific surface area of ​​porous carbon material is 39 m². ２ / g or more 200m ２ / g or less, 40m ２ / g or more 200m ２ It may be less than / g, and 40m ２ / g or more 150m ２ It may be less than / g, and 80m ２ / g or more 150m ２ It may be less than / g. The specific surface area is a value measured by the mercury intrusion method using a fully automated pore distribution analyzer, as described later.

[0029] The specific surface area of ​​porous carbon materials can be adjusted, for example, by appropriately selecting the raw materials for the porous carbon material or by appropriately adjusting the manufacturing conditions of the porous carbon material. When frass from beetle larvae is used as the raw material for the porous carbon material, as described later, the specific surface area of ​​the porous carbon material tends to be larger. Furthermore, when frass from insect larvae is used as the raw material for the porous carbon material, the specific surface area of ​​the porous carbon material can be increased by adjusting the activation temperature.

[0030] The average pore diameter of the porous carbon material is, for example, 0.05 μm or more, and may be 0.1 μm or more. Adsorption performance can be improved by having the average pore diameter within this range. On the other hand, the average pore diameter of the porous carbon material is, for example, 0.5 μm or less, and may be 0.2 μm or less. If the average pore diameter becomes too large, the density may decrease. Specifically, the average pore diameter of the porous carbon material is 0.05 μm or more and 0.5 μm or less, and may be 0.1 μm or more and 0.2 μm or less. The average pore diameter is a value measured by the mercury intrusion method using a fully automated pore distribution measuring device, as described later. The average pore diameter is the average pore diameter when the pores are assumed to be a single cylindrical shape. Therefore, even if the pores are not cylindrical, the pore diameter can be determined.

[0031] The median pore diameter of the porous carbon material is, for example, 1 μm or more, may be 10 μm or more, or 20 μm or more. Adsorption performance can be enhanced by having the median pore diameter within the above range. On the other hand, the median pore diameter of the porous carbon material is, for example, 55 μm or less, may be 50 μm or less, or 48 μm or less. If the median pore diameter becomes too large, the density may decrease. Specifically, the median pore diameter of the porous carbon material is 1 μm or more and 55 μm or less, may be 10 μm or more and 50 μm or less, or 20 μm or more and 48 μm or less. The median pore diameter is a value measured by the mercury intrusion method using a fully automated pore distribution analyzer, as described later. The median pore diameter is expressed as Normalized Volume [cm²], which represents the cumulative volume.３ In a graph with [ / g] on the vertical axis and pore diameter [μm] on the horizontal axis, this represents the pore diameter when the amount of mercury infiltration is half (50%).

[0032] The maximum pore diameter of the porous carbon material is, for example, 1 μm or more, may be 10 μm or more, or 50 μm or more. Adsorption performance can be enhanced by having the maximum pore diameter within the above range. On the other hand, the maximum pore diameter of the porous carbon material is, for example, 90 μm or less, may be 87 μm or less, or 82 μm or less. If the maximum pore diameter becomes too large, the density may decrease. Specifically, the maximum pore diameter of the porous carbon material is 1 μm or more and 90 μm or less, may be 10 μm or more and 87 μm or less, or 50 μm or more and 82 μm or less. The maximum pore diameter is a value measured by the mercury intrusion method using a fully automated pore distribution measuring device, as described later. The maximum pore diameter is expressed as the derivative of the cumulative volume with respect to logD -dV / dlogD [cm ３ In a graph with [ / g] on the vertical axis and pore diameter [μm] on the horizontal axis, this represents the pore diameter at which the amount of mercury penetration (change) is greatest.

[0033] The average pore diameter, median pore diameter, and maximum pore diameter of porous carbon materials can be adjusted, for example, by appropriately selecting the raw materials for the porous carbon material. When insect larval frass is used as the raw material for the porous carbon material, as described later, the average pore diameter, median pore diameter, and maximum pore diameter of the porous carbon material tend to be relatively large.

[0034] Cumulative pore volume, specific surface area, average pore diameter, median pore diameter, and maximum pore diameter are measured using a fully automated pore distribution analyzer (mercury porosimeter) by the mercury intrusion method. The measurement conditions are as follows: <Measurement Conditions> ・Mercury contact angle: 140° ・Mercury surface tension: 0.48 N / m ・Sample weight: 0.1 g to 0.5 g ・Cell size: 10 mmφ, 3 cm ・Measurement range: Entire range ・Measurement cell volume: 0.5 cm ３• Measurement range: Pore diameter 0.0036 μm to 400 μm • Calculation range: Pore diameter 0.0036 μm to 400 μm

[0035] The average particle size of the porous carbon material is 10 μm or more, and may be 20 μm or more. On the other hand, the average particle size of the porous carbon material is 200 μm or less, and may be 100 μm or less, 40 μm or less, or 35 μm or less. Specifically, the average particle size of the porous carbon material is 10 μm or more and 200 μm or less, may be 10 μm or more and 100 μm or less, may be 10 μm or more and 40 μm or less, or may be 20 μm or more and 35 μm or less. By having the average particle size of the porous carbon material within the above range, the adsorption performance can be improved.

[0036] The average particle size of a porous carbon material is the average value of the diameters of all particles in the particle size distribution obtained by laser diffraction scattering.

[0037] It is preferable that the particle size of the porous carbon material is uniform. Particle size uniformity can be evaluated using the arithmetic standard deviation, or D10, D50, or D90.

[0038] The arithmetic standard deviation of the particle size of the porous carbon material is preferably 70 μm or less, more preferably 29 μm or less, and even more preferably 25 μm or less. Specifically, the arithmetic standard deviation of the particle size of the porous carbon material is preferably 10 μm or more and 70 μm or less, more preferably 10 μm or more and 29 μm or less, even more preferably 15 μm or more and 29 μm or less, and particularly preferably 15 μm or more and 25 μm or less. By having the arithmetic standard deviation of the particle size of the porous carbon material within the above range, high adsorption performance can be achieved.

[0039] The arithmetic standard deviation of particle size in porous carbon materials is measured by laser diffraction scattering.

[0040] In the particle size distribution of porous carbon materials, it is preferable that D10, D50, and D90 satisfy the following equation: 1 ≤ (D90 - D10) / D50 ≤ 2.8. D10 indicates that 10% of the particles in the particle size distribution are of this particle size or smaller, and is the particle size of the smallest 10% of particles. D50 indicates the median of the particle size distribution, meaning that 50% of the particles are of this particle size or smaller, or of this particle size or larger. D50 is also commonly called the "intermediate particle size". D90 indicates that 90% of the particles in the particle size distribution are of this particle size or smaller, that is, the particle size of the largest 10% of particles.

[0041] The raw material for porous carbon materials is preferably the frass of insect larvae, more preferably the frass of beetle larvae, and even more preferably the frass of beetle larvae of the Tenebrionidae family. In other words, porous carbon materials are preferably derived from insect larvae frass, more preferably from beetle larvae, and even more preferably from beetle larvae of the Tenebrionidae family. The larvae of Tenebrionidae beetles are called mealworms. Porous carbon materials obtained using insect larvae frass as a raw material are novel materials. Furthermore, as mentioned above, by using insect larvae frass as a raw material for porous carbon materials, porous carbon materials that satisfy the above-mentioned pore characteristics are easily obtained. Insect larvae frass contains undigested material mainly composed of fiber, and it is presumed that by carbonizing and activating insect larvae frass containing such undigested material, porous carbon materials with deep pores can be obtained.

[0042] Furthermore, the larvae of Tenebrionidae beetles have the following characteristics: The final instar larvae are about 20 mm long, are omnivorous, easy to rear, and have a high reproductive rate. They contain more essential amino acids and unsaturated fatty acids than plant-based or other animal protein sources. Compared to livestock products such as cattle, they can be raised with less land and water, have lower greenhouse gas emissions, and have a lower environmental impact. They do not move around over a wide area and are raised on dry feed, making them hygienic and suitable for mass production as animal feed. Beetle larvae produce a large amount of frass during their growth process. Therefore, by manufacturing porous carbon materials from beetle larval frass, the frass of beetle larvae can be effectively utilized.

[0043] Furthermore, the frass of the larvae of Tenebrionidae beetles is dry, has fine particles, and is nearly spherical. Therefore, porous carbon materials that satisfy the above-mentioned average particle size and arithmetic standard deviation can be easily obtained in the manufacturing process of porous carbon materials without the need for crushing or sieving. It also has good fluidity.

[0044] Examples of beetles belonging to the family Tenebrionidae include Tenebrio obscurus, T. molitor, Tribolium castaneum, Alphitobius diaperinus, and Zophobas atratus / Zophobos morio.

[0045] In this specification, "frass" refers to the excrement that insects produce after digesting food.

[0046] As described above, the composition on the surface of porous carbon materials can be adjusted by appropriately selecting the food for insect larvae. Examples of food for insect larvae include wheat bran, corn, milo, barley, wheat, cassava and other root vegetables, rice bran, corn gluten meal, corn gluten feed, and silkworm cocoon.

[0047] A2. Second Embodiment of Porous Carbon Material The second embodiment of the porous carbon material in this disclosure has an average particle diameter of 10 μm or more and 200 μm or less, and a total pore volume measured by nitrogen gas adsorption method of 0.05 cm³. ３ / g or more 1.5cm ３ It is less than or equal to / g.

[0048] In this embodiment, since the total pore volume measured by the nitrogen gas adsorption method is within a predetermined range, the pore depth is considered to be relatively large. Therefore, high adsorption performance can be achieved.

[0049] The following describes the structure of the porous carbon material in this embodiment.

[0050] The composition on the surface of the porous carbon material is the same as that described in the first embodiment above.

[0051] The total pore volume measured by the nitrogen gas adsorption method is 0.05 cm³. ３ It is 0.2 cm or more per gram. ３ Preferably 0.3 cm or more per gram. ３ More preferably 0.5 cm or more per gram. ３ It may be 1.5 cm² or more. High adsorption performance can be achieved when the total pore volume is within the above range. On the other hand, the total pore volume is 1.5 cm². ３ It is less than / g and 1.0 cm ３ It may be less than / g, and 0.6 cm ３ It may be less than / g. If the total pore volume becomes too large, the specific surface area may decrease. Specifically, the total pore volume is 0.05 cm³. ３ / g or more 1.5cm ３ It is less than / g and 0.2cm ３ / g or more 1.0cm ３ It may be less than or equal to 0.3 cm. ３ / g or more 0.6cm ３ It may be less than / g, and 0.5 cm ３ / g or more 0.6cm ３ The value may be less than or equal to / g. The above pore volume is a value measured by the nitrogen gas adsorption method using a fully automated gas adsorption measuring device, as described later.

[0052] The total pore volume of porous carbon materials can be adjusted, for example, by appropriately selecting the raw materials for the porous carbon material or by appropriately adjusting the manufacturing conditions of the porous carbon material. When beetle larval frass is used as the raw material for the porous carbon material, as described later, the total pore volume of the porous carbon material tends to be larger. Furthermore, when insect larval frass is used as the raw material for the porous carbon material, the total pore volume of the porous carbon material can be made relatively large by adjusting the activation temperature.

[0053] The BET specific surface area of ​​a porous carbon material is, for example, 230 m². ２ Preferably 1 / g or more, 450m ２ More preferably 600m / g or more. ２ More preferably 650m / g or more. ２ It may be 1 / g or more. A BET specific surface area within the above range allows for high adsorption performance. On the other hand, the BET specific surface area of ​​a porous carbon material is, for example, 1200 m². ２ It may be less than / g, and 1000m ２ It may be less than / g, and 800m ２ It may be less than / g, and 750m ２ It may be less than / g. If the BET specific surface area becomes too large, the density will decrease, and the strength may decrease. Specifically, the BET specific surface area of ​​porous carbon material is 230 m². ２ / g or more 1200m ２ It may be less than / g, and 450m ２ / g or more 1000m ２ It may be less than / g, and 600m ２ / g or more 800m ２ It may be less than / g, and 650m ２ / g or more 750m ２ It may be less than or equal to / g. The BET specific surface area is a value measured by the nitrogen gas adsorption method using a fully automated gas adsorption measuring device, as described later.

[0054] The BET specific surface area of ​​porous carbon materials can be adjusted, for example, by appropriately selecting the raw materials for the porous carbon material or by appropriately adjusting the manufacturing conditions of the porous carbon material. When beetle larval frass is used as the raw material for the porous carbon material, as described later, the BET specific surface area of ​​the porous carbon material tends to be larger. Furthermore, when insect larval frass is used as the raw material for the porous carbon material, the BET specific surface area of ​​the porous carbon material can be increased by adjusting the activation temperature.

[0055] The total pore volume and BET specific surface area are measured using a fully automated gas adsorption analyzer in accordance with JIS Z8831:2024, by the nitrogen gas adsorption method (constant volume method). The conditions are as follows. As the fully automated gas adsorption analyzer, the Quantachrome AS-iQ-MP3-C fully automated gas adsorption analyzer can be used. <Conditions> ・Pretreatment: Place the sample in the measurement cell and vacuum degas it at 100°C for 12 hours. ・Measurement principle: Fully automated gas adsorption measurement by constant volume method ・Adsorbed gas: Nitrogen gas ・Measurement temperature: 77.3K ・Cell size: Standard cell (small) (stem outer diameter 6 mmφ) ・Measurement relative pressure: 1 × 10⁻⁶ －６ Above 1 or below: Measurement items: Adsorption / desorption isotherms at arbitrary measurement points; Analysis items: Specific surface area, total pore volume, average pore diameter by BET multipoint method; Pore size distribution (mesopore region) by BJH method; Pore size distribution (micropore to mesopore region) by DFT method.

[0056] In this specification, the definitions of "micropore" and "mesopore" are based on the IUPAC.

[0057] The average pore diameter, median pore diameter, and maximum pore diameter of the porous carbon material are the same as those described in the first embodiment above. Furthermore, the average particle diameter, arithmetic standard deviation of particle diameter, and particle size distribution of the porous carbon material are also the same as those described in the first embodiment above.

[0058] The raw materials for the porous carbon material are the same as those described in the first embodiment above.

[0059] A3. Third Embodiment of Porous Carbon Material The third embodiment of the porous carbon material in this disclosure is derived from the frass of the larva of a Tenebrionidae beetle.

[0060] As mentioned above, using the frass of the larvae of Tenebrionidae beetles as a raw material for porous carbon materials makes it easier to obtain porous carbon materials that satisfy the aforementioned pore characteristics. The frass of the larvae of Tenebrionidae beetles contains undigested material mainly composed of fiber, and it is presumed that by carbonizing and activating such frass containing undigested material, porous carbon materials with deep pores can be obtained.

[0061] The pore properties of the porous carbon material, the composition on the surface of the porous carbon material, and the raw materials of the porous carbon material are the same as those described in the first and second embodiments above.

[0062] B. Method for producing porous carbon material The method for producing porous carbon material in this disclosure comprises a carbonization step of carbonizing the frass of an insect larva.

[0063] In this disclosure, since insect larval frass is used as a raw material, a novel porous carbon material can be obtained. Furthermore, insect larvae produce a large amount of frass during their growth process. Therefore, by manufacturing a porous carbon material from insect larval frass, insect larval frass can be effectively utilized.

[0064] The following describes each step in the method for producing porous carbon materials as described in this disclosure.

[0065] 1. The raw material for the porous carbon material in the carbonization process is frass from insect larvae, with frass from beetle larvae being preferred, and frass from beetle larvae of the family Tenebrionidae being more preferred. The reasons for this preference are the same as those described in section A. Porous Carbon Material above.

[0066] It is preferable to dry the insect larval frass before carbonization. This can suppress the generation of ammonia and other substances. The drying temperature is, for example, 60°C to 90°C. The drying time is, for example, 8 hours to 10 hours.

[0067] As mentioned above, the frass of the larvae of Tenebrionidae beetles is dry and finely granulated. The form of insect larval frass may be powder or aggregates of particles. Examples of aggregates of particles include granules and pellets. When the form of insect larval frass is aggregates of particles, it is possible to suppress the scattering of particles and improve handling. In addition, in the case of aggregates of particles, since the scattering of particles can be suppressed in the activation process described later, the reaction between insect larval frass and gas can be carried out with good reproducibility, and porous carbon material can be stably produced. When insect larval frass is untreated, the form of the frass is usually powder.

[0068] The conditions for carbonization are not particularly limited as long as the frass of the insect larva can be carbonized. The carbonization temperature is, for example, 100°C to 1000°C, or 100°C to 500°C. The atmosphere may be an air atmosphere or an inert gas atmosphere. Nitrogen, argon, etc., are preferred as inert gases. During carbonization, it is preferable to place the insect larval frass in a sealed container.

[0069] 2. Activation Step The method for producing a porous carbon material in this disclosure preferably includes an activation step in which the carbide obtained in the carbonization step is activated using a gas. The porous carbon material produced by this method exhibits high adsorption performance.

[0070] In the activation process, a gas activation method is used. Examples of activation gases include carbon dioxide gas, nitrogen gas, and water vapor. The activation gas may be used alone or as a mixture of two or more. When mixing activation gases, it is preferable to keep the ratio of carbon dioxide gas to nitrogen gas within the range of 1:9 to 9:1 in terms of flow rate ratio. The activation gas should be supplied at an adjustable flow rate.

[0071] Furthermore, when using carbon dioxide gas and / or water vapor, it is preferable to heat the carbide in an atmosphere of carbon dioxide gas and / or water vapor at a temperature of 800°C to 1300°C. By keeping the activation temperature within a predetermined range, it is possible to obtain a porous carbon material with a relatively large cumulative pore volume measured by the mercury intrusion method, or a porous carbon material with a relatively large total pore volume measured by the nitrogen gas adsorption method. Thus, it is possible to manufacture a porous carbon material with excellent adsorption performance.

[0072] When activating using steam, the above-mentioned carbide may be heated in the presence of water at a temperature of 800°C to 1300°C. This is because the water turns into steam during heating and comes into contact with the carbide, thereby activating it. In this case, the amount of water heated together with the carbide may be between 0.5 and 1.5 times the mass of the carbide.

[0073] In the above case, the activation temperature is preferably between 800°C and 1300°C. By setting the activation temperature within the above range, it is possible to obtain a porous carbon material with a relatively large cumulative pore volume measured by the mercury intrusion method, or a porous carbon material with a relatively large total pore volume measured by the nitrogen gas adsorption method. The activation time is set appropriately to satisfy the activation yield described later, and may be, for example, between 15 minutes and 600 minutes. By making the activation time relatively long within the above range, it is possible to produce a porous carbon material with excellent adsorption performance.

[0074] Furthermore, the activation yield is preferably between 15% and 90%. If the activation yield is within the above range, the desired porous carbon material can be obtained. The activation yield can be calculated using the following formula: Activation yield (%) = Mass of porous carbon material after the activation process / Mass of carbide obtained in the carbonization process × 100

[0075] The resulting porous carbon material is the same as described in section "A. Porous Carbon Material" above.

[0076] 3. Pelleting Process In this disclosure, as described above, if the form of the insect larval frass is pellets, a pelletizing process may be performed to pelletize the insect larval frass before the carbonization process. As described above, in the case of pellets, the scattering of particles can be suppressed and handling can be improved. Also, in the case of pellets, since the scattering of particles can be suppressed in the activation process, the reaction between the insect larval frass and gas can be carried out with good reproducibility, and porous carbon material can be stably produced.

[0077] The pelletizing method is not particularly limited, but one example is wet granulation, in which a solvent such as water is added to the frass of insect larvae. This pelletizing method is usually carried out at room temperature, but may be carried out under heating in some cases. In addition, additives or binders may be added to improve moldability or for other purposes.

[0078] The shape of the pellet is not particularly limited, and for example, it can be cylindrical. In the case of a cylinder, the diameter may be, for example, 3 mm to 12 mm, and the length may be, for example, 10 mm to 40 mm. The surface area that the activating gas comes into contact with (so to speak, the contact frequency) can change depending on the size of the pellet. It is presumed that if the particles are fine, the contact frequency increases and the activation proceeds favorably. Therefore, it is preferable that the pellet is not too large.

[0079] 4. Grinding Process In this disclosure, as described above, if the form of the insect larval frass is pellets, it is preferable to perform a grinding process to grind the obtained porous carbon material after the activation process. This makes it possible to produce a porous carbon material with excellent adsorption performance.

[0080] The crushing method is not particularly limited; for example, a crusher can be used.

[0081] 5. Sieving Process In this disclosure, a sieving process may be performed after the grinding process to sieve the obtained porous carbon material. A porous carbon material having a predetermined average particle size can be obtained.

[0082] The sieving method is not particularly limited; for example, a sieving machine can be used. The sieve opening is appropriately selected according to the desired average particle size. The average particle size of the obtained porous carbon material is the same as described in section "A. Porous Carbon Material" above.

[0083] C. Method for purifying water or air The method for purifying water or air in this disclosure is a method using the porous carbon material described above.

[0084] Porous carbon materials are used for water purification, including the treatment of factory wastewater, sewage, tap water, and the purification of raw water for drinking. By bringing these porous carbon materials into contact with water, harmful substances, odor-causing substances, color-causing substances, etc., contained in the water can be adsorbed and removed. This improves water quality and enhances safety.

[0085] Furthermore, porous carbon materials are used for air purification, such as in the treatment of factory exhaust gases and air conditioning. By bringing the aforementioned porous carbon materials into contact with exhaust gases, harmful substances or odor-causing substances contained in the exhaust gases can be adsorbed and removed. This helps to keep the air clean.

[0086] D. Adsorbent The adsorbent in this disclosure includes the porous carbon material described above. Because the porous carbon material has good adsorption performance, it can be used in various applications and is suitable for use as an adsorbent.

[0087] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure.

[0088] Examples and comparative examples are shown below to further illustrate this disclosure.

[0089] [Example 1] As raw material, frass of the larvae of Tenebrionidae beetle T. molitor, which was fed wheat bran, was used. First, the frass was dried overnight at 70°C. Next, the frass was placed in a container, sealed with a lid, and placed in an electric kiln. The temperature was raised to 800°C at a rate of 1°C / min and held at 800°C for 15 minutes to carbonize it. Next, the obtained carbonized material was placed in a rotary kiln (Special FUR122, manufactured by Advantec Toyo Co., Ltd.), and carbon dioxide gas was circulated through it. The temperature was raised to 950°C at a rate of 1°C / min and held at 950°C for 30 minutes to activate it. This yielded a porous carbon material.

[0090] [Example 2] A porous carbon material was prepared in the same manner as in Example 1, except that the activation temperature was set to 1000°C.

[0091] [Example 3] A porous carbon material was prepared in the same manner as in Example 1, except that the holding time in the activation process was set to 15 minutes.

[0092] [Example 4] A porous carbon material was prepared in the same manner as in Example 1, except that water vapor was used instead of carbon dioxide gas.

[0093] [Example 5] The frass was dried in the same manner as in Example 1. Next, the frass was placed in a porcelain crucible, sealed with a lid, and the container was placed in an electric kiln. The temperature was raised to 800°C at a rate of 1°C / min and held at 800°C for 15 minutes to carry out carbonization. Next, the obtained char was placed in the same electric kiln and, in the presence of water approximately 1 mass-equivalent to the char, the temperature was raised to 950°C at a rate of 1°C / min and held at 950°C for 30 minutes to carry out activation. A porous carbon material was obtained as a result.

[0094] [Example 6] A porous carbon material was prepared in the same manner as in Example 1, except that the frass of a Tenebrionidae beetle larva, which was fed corn gluten as feed, was used as the raw material, and the activation temperature was set to 1000°C.

[0095] [Example 7] As the raw material, frass from the larvae of Tenebrionidae beetles, the same as in Example 1, was used. The moisture content of the raw material was adjusted from 15% to 9% from a starting moisture content of 4%, and molding was performed. The pelletizer die temperature did not rise due to the small amount of raw material, and processing was performed at almost room temperature. With the addition of 5% water, pellets with a bulk density of 0.74 g / mL and a moisture content of 7% were produced. The above pellets were placed in a large activated carbon experimental machine and carbonized at 850°C. Next, the obtained carbonized material was placed in a small activated carbon experimental machine and activated at a temperature of 850°C, a water vapor supply of 12 g / min, and a holding time of 300 minutes. During this process, nitrogen purging was performed to avoid contact with oxygen during heating and cooling. Next, the obtained porous carbon material was crushed using a pulverizer (Labonect "High Speed ​​Mill") under the condition of 5 seconds x 4 times. Subsequently, the porous carbon material was passed through a commercially available sieve with a mesh size of 45 μm, and the porous carbon material that passed through the sieve was collected. This yielded porous carbon material.

[0096] [Example 8] A porous carbon material was prepared in the same manner as in Example 7, except that the holding time in the activation process was set to 570 minutes.

[0097] [Examples 9-10] Porous carbon materials were prepared in the same manner as in Example 7, except that carbon dioxide gas was used instead of water vapor, the carbon dioxide gas supply rate was set to 5.6 L / min, and the temperature in the activation process was set to 900°C with a holding time of 200 minutes or 360 minutes.

[0098] [Example 11] As raw material, frass of the larvae of Tenebrionidae beetle T. molitor, which was fed wheat bran, was used. First, the frass was dried overnight at 70°C. Next, the frass was placed in a small batch-type rotary kiln and heated to 800°C at a heating rate of 300°C / h, held at 800°C for 15 minutes, and then heated to 900°C at a heating rate of 300°C / h, held at 900°C for 30 minutes to carbonize it. After cooling, the obtained carbonized material was heated to 850°C at a steam flow rate of 1 kg / h and a heating rate of 300°C / h in the rotary kiln, and held at 850°C for 180 minutes to activate it. This yielded a porous carbon material.

[0099] [Example 12] A porous carbon material was prepared in the same manner as in Example 11, except that carbon dioxide gas was used instead of superheated steam, the carbon dioxide gas flow rate was set to 50 L / min, and the temperature in the activation process was set to 900°C.

[0100] [Comparative Example 1] Activated carbon (granular) SAJ Grade 1 manufactured by Sigma-Aldrich Japan was used.

[0101] [Evaluation] (1) Elemental analysis (EDX) An elemental analysis was performed on the surface of a porous carbon material using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDX), specifically the "SU3500" manufactured by Hitachi High-Technologies Corporation, under the following conditions.

[0102] <Measurement Conditions> - Acceleration voltage: 15kV - SEM aperture: 80μm - Sample tilt: 0° - Working distance (WD): 10mm

[0103] (2) Pore characteristics (2-1) Mercury intrusion method The cumulative pore volume, specific surface area, average pore diameter, median pore diameter, and maximum pore diameter of porous carbon material were measured using the Pore Master 60-GT, a fully automated pore distribution analyzer manufactured by Quantachrome, under the following conditions.

[0104] <Measurement Conditions> • Mercury contact angle: 140° • Mercury surface tension: 0.48 N / m • Sample weight: 0.1 g to 0.5 g • Cell size: Small cell (10 mm diameter, 3 cm) • Measurement range: Entire range • Measurement cell volume: 0.5 cm³ ３ • Measurement range: Pore diameter 400 μm to 0.0036 μm • Calculation range: Pore diameter 400 μm to 0.0036 μm (entire range)

[0105] (2-2) Nitrogen Gas Adsorption Method Using the fully automated gas adsorption amount measuring device "AS-iQ-MP3-C" manufactured by Quantachrome, the total pore volume and BET specific surface area of ​​the porous carbon material were measured under the following conditions using the nitrogen gas adsorption method (constant volume method) in accordance with JIS Z8831:2024.

[0106] <Measurement Conditions> ・Pretreatment: Place the sample in the measurement cell and vacuum degas at 100°C for 12 hours. ・Measurement Principle: Fully automated gas adsorption amount measurement by constant volume method. ・Adsorbed Gas: Nitrogen gas ・Measurement Temperature: 77.3K ・Cell Size: Standard cell (small) (Stem outer diameter 6 mmφ) ・Measurement Relative Pressure: 1 × 10⁻⁶ －６ Above 1 or below: Measurement items: Adsorption / desorption isotherms at arbitrary measurement points; Analysis items: Specific surface area, total pore volume, average pore diameter by BET multipoint method; Pore size distribution (mesopore region) by BJH method; Pore size distribution (micropore to mesopore region) by DFT method.

[0107] (3) Average particle size and arithmetic standard deviation Using the LA-950V2 laser diffraction scattering particle size distribution analyzer manufactured by Horiba, Ltd., the average particle size, arithmetic standard deviation of particle size, D10, D50, and D90 of the porous carbon material were measured under the following conditions. D10 is the particle size at which the cumulative 10% of the particle size distribution is reached, D50 is the particle size at which the cumulative 50% of the particle size distribution is reached, and D90 is the particle size at which the cumulative 90% of the particle size distribution is reached.

[0108] <Measurement Conditions> ・Measurement Unit: Wet type ・Measurement Mode: Manual flow cell measurement ・Measurement Range: 0.01 μm to 3000 μm ・Particle Size Reference: Volume reference ・Dispersion Medium: Ethanol ・Refractive Index: 1.92-0.52i (sample refractive index) / 1.36-0.00i (dispersion medium refractive index) ・Sample Pretreatment: The sample was collected in a screw tube, ethanol was added, and ultrasonic dispersion was performed for 10 minutes to prepare the measurement solution. ・Number of Measurements: Two measurements were taken with different samples.

[0109] (4) Adsorption Performance (4-1) Methylene Blue Concentration An aqueous solution with a methylene blue concentration of 1200 mg / L was prepared. First, 200 mg of porous carbon material was added to the aqueous solution and shaken at 25°C and 200 rpm for 1 hour. Then, the porous carbon material was precipitated using a centrifuge and the supernatant was collected. Next, the methylene blue concentration of the aqueous solution after the addition of the porous carbon material was determined from the supernatant using the calibration curve method. Specifically, the methylene blue concentration of the aqueous solution was calculated using a calibration curve obtained from the absorbance of several samples with known concentrations. The adsorption performance was then evaluated according to the following criteria. A: The methylene blue concentration in the aqueous solution is 100 mg / L or less (shows significant adsorption activity, and the concentration change before and after the addition of porous carbon material is remarkable). B: The methylene blue concentration in the aqueous solution is greater than 100 mg / L and 600 mg / L or less. C: The methylene blue concentration in the aqueous solution is greater than 600 mg / L and 900 mg / L or less. D: The methylene blue concentration in the aqueous solution is greater than 900 mg / L and 1100 mg / L or less. E: The methylene blue concentration in the aqueous solution is greater than 1100 mg / L (shows almost no adsorption, and there is no concentration change before and after the addition of porous carbon material).

[0110] (4-2) Adsorption rate The adsorption rate was calculated using the following formula: Adsorption rate (%) = [(1200 - C) １ ) / 1200] × 100 In the above formula, C １ The following table shows the methylene blue concentration of the aqueous solution after the addition of porous carbon material. The adsorption performance was evaluated according to the following criteria: A: Adsorption rate (%) is 91.6% or higher (shows significant adsorption activity, and the concentration change before and after the addition of porous carbon material is significant) B: Adsorption rate (%) is 50% or higher and less than 91.6% C: Adsorption rate (%) is 25% or higher and less than 50% D: Adsorption rate (%) is 8.3% or higher and less than 25% E: Adsorption rate (%) is less than 8.3% (shows almost no adsorption, and there is no concentration change before and after the addition of porous carbon material)

[0111] (5) Activation yield The activation yield was determined from the mass after the carbonization process and the mass after the activation process. Activation yield (%) = Mass of porous carbon material after the activation process / Mass of carbide obtained in the carbonization process × 100

[0112] In Examples 11 and 12, the carbonization and activation processes were carried out consecutively, resulting in a two-stage activation yield. The activation yield in the two-stage case was calculated using the following formula: Activation yield (two-stage yield) (%) = Mass of porous carbon material after activation process / Mass of raw material × 100

[0113]

[0114]

[0115] In Table 2 above, "-" indicates that the measurement was not taken.

[0116]

[0117] In Examples 1-4 and 7-12, all elements Mg, P, and K were detected on the surface of the porous carbon material by EDX. The porous carbon material was made using frass from the larvae of Tenebrionidae beetles, and these elements are thought to originate from the food of the larvae. On the other hand, in Comparative Example 1, which was a commercially available activated carbon, none of the elements Mg, P, and K were detected on the surface of the activated carbon by EDX.

[0118] Furthermore, Examples 1 to 12 showed better adsorption performance compared to Comparative Example 1. Specifically, in Examples 1 to 12, the cumulative pore volume was within a predetermined range, resulting in good adsorption performance. On the other hand, in Comparative Example 1, the cumulative pore volume was small, resulting in inferior adsorption performance. Also, a comparison of Examples 1 to 12 showed a tendency for adsorption performance to improve when the cumulative pore volume was large within a predetermined range. Similarly, a comparison of Examples 1 to 12 showed a tendency for adsorption performance to improve when the total pore volume was large within a predetermined range. Also, a comparison of Examples 1 to 12 showed a tendency for adsorption performance to improve when the average particle size was small. Furthermore, in Example 10, the use of carbon dioxide gas in the activation process and the relatively long holding time resulted in excellent adsorption performance.

[0119] (5) SEM Observation The porous carbon material of Example 1 was observed using a scanning electron microscope (SEM). The SEM image is shown in Figure 1. For reference, Figure 2 shows an SEM image of the frass of a Tenebrionidae beetle larva used as a raw material for the porous carbon material. The porous carbon material of Example 1 had a rounded shape.

[0120] In this disclosure, for example, the following inventions are provided: [1] A particle having an average particle diameter of 10 μm or more and 200 μm or less, and a cumulative pore volume of 0.2 cm³ with a pore diameter of 0.0036 μm or more and 400 μm or less, as measured by mercury intrusion. ３ / g or more 9cm ３ [2] A porous carbon material having an average particle size of 10 μm or more and 200 μm or less, and a total pore volume of 0.05 cm³ measured by nitrogen gas adsorption method. ３ / g or more 1.5cm ３[1] to [2] A porous carbon material having a particle size of 70 μm or less. [3] A porous carbon material according to [1] or [2], derived from the frass of an insect larva. [4] A porous carbon material according to [3], wherein the insect belongs to the family Tenebrionidae. [5] A porous carbon material according to any one of [1] to [4], wherein at least one element selected from the group consisting of Mg, P, and K is detected on the surface of the porous carbon material by energy dispersive X-ray analysis. [6] A porous carbon material according to any one of [1] to [5], wherein the arithmetic standard deviation of the particle size is 70 μm or less. [7] A porous carbon material derived from the frass of a beetle of the family Tenebrionidae. [8] A method for producing a porous carbon material, comprising a carbonization step of carbonizing the frass of an insect larva. [9] A method for producing a porous carbon material according to [8], comprising an activation step of heating the carbide obtained in the carbonization step in an atmosphere of carbon dioxide gas and / or water vapor at 800°C to 1300°C.

[10] A method for producing a porous carbon material according to [8] or [9], further comprising a pelletizing step of pelletizing the frass before the carbonization step.

[11] A method for producing a porous carbon material according to

[10] , further comprising a grinding step of grinding the obtained porous carbon material after the activation step.

[12] A method for producing a porous carbon material according to

[11] , further comprising a sieving step of sieving the obtained porous carbon material after the grinding step.

[13] The average particle diameter of the porous carbon material is 10 μm or more and 40 μm or less, and the cumulative pore volume of the porous carbon material with a pore diameter of 0.0036 μm or more and 400 μm or less, as measured by the mercury intrusion method, is 0.2 cm³. ３ / g or more 9cm ３ A method for producing a porous carbon material according to any one of [8] to

[12] , wherein the amount is less than or equal to / g.

[14] The porous carbon material has an average particle diameter of 10 μm or more and 200 μm or less, and the total pore volume measured by nitrogen gas adsorption is 0.05 cm³. ３ / g or more 1.5cm ３A method for producing a porous carbon material according to any one of [8] to

[13] , wherein the amount is less than or equal to / g.

[15] A method for producing a porous carbon material according to any one of [8] to

[14] , wherein the arithmetic standard deviation of the particle size of the porous carbon material is 29 μm or less.

[16] A method for purifying water or air using the porous carbon material according to any one of [1] to [7].

[17] An adsorbent comprising the porous carbon material according to any one of [1] to [7].

[0121] Furthermore, the present disclosure provides, for example, the following invention: [1A] A particle with an average particle diameter of 10 μm or more and 40 μm or less, and a cumulative pore volume of 0.2 cm³ with a pore diameter of 0.0036 μm or more and 400 μm or less, as measured by the mercury intrusion method. ３ / g or more 9cm ３ Porous carbon material with a density of less than / g.

Claims

1. The average particle diameter is 10 μm or more and 200 μm or less, and the cumulative pore volume, measured by the mercury intrusion method, is 0.2 cm³ for pore diameters of 0.0036 μm or more and 400 μm or less. ３ / g or more 9cm ３ Porous carbon material with a density of less than / g.

2. The average particle size is 10 μm or more and 200 μm or less, and the total pore volume measured by nitrogen gas adsorption is 0.05 cm³. ３ / g or more 1.5cm ３ Porous carbon material with a density of less than / g.

3. A porous carbon material according to claim 1 or claim 2, derived from the frass of an insect larva.

4. The porous carbon material according to claim 3, wherein the insect belongs to the family Tenebrionidae.

5. The porous carbon material according to claim 1 or 2, wherein at least one element selected from the group consisting of Mg, P, and K is detected on the surface of the porous carbon material by energy-dispersive X-ray analysis.

6. The porous carbon material according to claim 1 or claim 2, wherein the arithmetic standard deviation of the particle size is 70 μm or less.

7. A porous carbon material derived from the frass of the larvae of Tenebrionidae beetles.

8. A method for producing a porous carbon material, comprising a carbonization step of carbonizing the frass of an insect larva.

9. The method for producing a porous carbon material according to claim 8, further comprising an activation step of heating the carbide obtained in the carbonization step in an atmosphere of carbon dioxide gas and / or water vapor at a temperature of 800°C to 1300°C.

10. A method for producing a porous carbon material according to claim 8 or 9, comprising a pelletizing step of pelletizing the frass before the carbonization step.

11. A method for producing a porous carbon material according to claim 10, comprising a grinding step of grinding the porous carbon material obtained after the activation step.

12. A method for producing a porous carbon material according to claim 11, further comprising a sieving step of sieving the porous carbon material obtained after the grinding step.

13. The average particle size of the porous carbon material is 10 μm or more and 200 μm or less, and the cumulative pore volume of the porous carbon material with a pore diameter of 0.0036 μm or more and 400 μm or less, as measured by the mercury intrusion method, is 0.2 cm³. ３ / g or more 9cm ３ A method for producing a porous carbon material according to claim 8 or claim 9, wherein the amount is less than or equal to / g.

14. The average particle size of the porous carbon material is 10 μm or more and 200 μm or less, and the total pore volume measured by nitrogen gas adsorption is 0.05 cm³. ３ / g or more 1.5cm ３ A method for producing a porous carbon material according to claim 8 or claim 9, wherein the amount is less than or equal to / g.

15. The method for producing a porous carbon material according to claim 8 or 9, wherein the arithmetic standard deviation of the particle size of the porous carbon material is 70 μm or less.

16. A method for purifying water or air using a porous carbon material according to any one of claims 1 to 7.

17. An adsorbent comprising the porous carbon material according to any one of claims 1 to 7.

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