Method for manufacturing compression molded body

Abstract

This invention forms a compression molded body having excellent gas adsorption characteristics.　This method for manufacturing a compression molded body includes: filling a container with porous powder; and forming a compression molded body by compressing the porous powder so as to satisfy the following conditions (1) or (2) in a state where gas is sealed in the container and the gas is adsorbed to the porous powder. (1) The temperature of the gas is equal to or higher than the critical temperature; and (2) the temperature of the gas is less than the critical temperature, and the pressure of the gas is less than the critical pressure.

Description

Method for producing compression molded body

[0001] The present invention relates to a method for producing a compression molded product.

[0002] Conventionally, compression-molded bodies have been used as gas adsorbents. In a method for producing a compression-molded body, a porous powder is filled in a mold in advance, and when the porous powder is molded using a compression molding machine (tablet press), pressure is applied to the porous powder to compress and mold it. In addition, other methods for producing a compression-molded body include a method of mixing a binder between the porous powder to improve the moldability of the compression-molded body, and a method of filling the porous powder with a liquid to improve the moldability of the compression-molded body.

[0003] Patent Document 1 (JP 2023-69429 A) discloses a method for manufacturing a compression-molded body, which includes the steps of placing metal pillars in a mold, filling the mold with magnetic particles, compressing the magnetic particles, and removing excess compressed magnetic particles to form a molded body.

[0004] Here, porous powders often have low packing densities due to their high specific surface area. For this reason, attempts have been made to improve the packing density of porous powders by compression molding or other methods. However, when conventional compression molding is performed on conventional porous powders such as organometallic complexes, the pore structure is destroyed. Furthermore, methods that involve mixing a binder between the porous powder particles have problems, such as a decrease in the adsorption capacity of the compression-molded product because the binder contains a material that does not contribute to gas adsorption. Molding that involves filling a liquid into a porous powder cannot prevent the pores in the porous powder from clogging, necessitating a process for removing the liquid after molding.

[0005] Japanese Patent Application Laid-Open No. 2023-69429

[0006] The present invention has been made in view of the above problems. The present invention relates to a compression-molded body formed by filling a container with porous powder and compressing the porous powder while the porous powder has adsorbed a gas. Specifically, the present inventors discovered that if gas molecules are maintained in the pores of the porous powder and compression molding is performed such that the gas temperature is equal to or higher than the critical temperature, or the gas temperature is below the critical temperature and the gas pressure is below the critical pressure, the pore structure of the porous powder is maintained by the gas molecules adsorbed in the pores, and the pore structure is not destroyed even when the porous powder is compressed. This discovery led to the completion of the present invention. Thus, the present invention aims to obtain a compression-molded body having excellent gas adsorption properties without reducing the performance of the porous powder compared to before compression molding.

[0007] The method for producing a compression-molded body of the present invention includes the steps of: filling a container with porous powder; and, with a gas sealed in the container and the porous powder having the gas adsorbed therein, compressing the porous powder to form a compression-molded body so as to satisfy the following condition (1) or (2): (1) the temperature of the gas is equal to or higher than a critical temperature; or (2) the temperature of the gas is lower than the critical temperature and the pressure of the gas is lower than a critical pressure.

[0008] The porous powder is preferably selected from metal organic frameworks (MOFs), activated carbon, and zeolites.

[0009] The gas is CO ２ and ethane.

[0010] In the step of forming the compression-molded body, it is preferable that the gas desorbed from the compression-molded body is stored in a buffer chamber that communicates with the container.

[0011] The gas is CO ２ In the step of forming the compression molded body, ２Preferably, the porous powder is compressed so that the pressure of the gas is 1.0 to 7.0 MPa. Preferably, the gas is ethane, and in the step of forming the compression-molded body, the porous powder is compressed so that the pressure of the ethane is 2.0 to 4.5 MPa.

[0012] A compression molded body having excellent gas adsorption properties can be formed.

[0013] FIG. 1 is a diagram showing a method for producing a compression-molded body according to one embodiment. FIG. 2 is a diagram showing a method for producing a compression-molded body according to another embodiment. FIG. 3 is a diagram showing a methane adsorption isotherm of a compression-molded body formed using HKUST1 as the porous powder and carbon dioxide as the filling gas. FIG. 4 is a diagram showing a methane adsorption isotherm of a compression-molded body formed using HKUST1GO as the porous powder and carbon dioxide as the filling gas. FIG. 5 is a diagram showing an estimated value of the methane storage capacity of a compression-molded body formed using HKUST1 as the porous powder and carbon dioxide as the filling gas. FIG. 6 is a diagram showing an estimated value of the methane storage capacity of a compression-molded body formed using HKUST1GO as the porous powder and carbon dioxide as the filling gas. FIG. 7 is a diagram showing a methane adsorption isotherm of a compression-molded body formed using HKUST1GO as the porous powder and carbon dioxide as the filling gas. FIG. 8 is a diagram showing an estimated value of the methane storage capacity of a compression-molded body formed using HKUST1GO as the porous powder and carbon dioxide as the filling gas. FIG. 9 is a graph showing the methane adsorption isotherm of a compression-molded body formed using HKUST1 as the porous powder and ethane as the filling gas. FIG. 10 is a graph showing the estimated value of the methane storage capacity of a compression-molded body formed using HKUST1 as the porous powder and ethane as the filling gas. FIG. 11 is a graph showing the methane adsorption isotherm of a compression-molded body formed using HKUST1GO as the porous powder and ethane as the filling gas. FIG. 12 is a graph showing the estimated value of the methane storage capacity of a compression-molded body formed using HKUST1GO as the porous powder and ethane as the filling gas. FIG. 13 is a graph showing the methane adsorption isotherm of a compression-molded body formed using MOF-177 as the porous powder and ethane as the filling gas. FIG. 14 is a graph showing the estimated value of the methane storage capacity of a compression-molded body formed using MOF-177 as the porous powder and ethane as the filling gas. Fig. 15 is a graph showing methane adsorption isotherms for a compression-molded body formed using activated carbon as the porous powder and ethane as the filling gas, and Fig. 16 is a graph showing estimated values ​​of methane storage amounts for a compression-molded body formed using activated carbon as the porous powder and ethane as the filling gas.

[0014] (Method for Producing a Compression-Molded Body) The method for producing a compression-molded body of the present invention includes the steps of filling a container with porous powder and, with a gas sealed in the container and the porous powder adsorbing the gas, compressing the porous powder to form a compression-molded body so that the following condition (1) or (2) is satisfied: (1) the gas temperature is equal to or higher than the critical temperature; or (2) the gas temperature is below the critical temperature and the gas pressure is below the critical pressure. In conventional methods for producing compression-molded bodies, the pore structure within the porous powder is destroyed during compression molding, resulting in pore blockage. As a result, the performance of the porous powder produced by conventional methods for producing compression-molded bodies is inferior, and the resulting compression-molded body does not have sufficient gas adsorption properties. In contrast, the method for producing a compression-molded body of the present invention performs compression molding so as to satisfy the above condition (1) or (2), thereby producing a compression-molded body with a high packing density of the porous powder. Furthermore, in the method for producing a compression-molded body of the present invention, compression molding is performed while maintaining a state in which gas molecules have been previously adsorbed into the pores of the porous powder. In this case, since the compression molding is performed so as to satisfy the above condition (1) or (2), liquefaction of the gas during compression molding can be prevented. Therefore, the pore structure of the porous powder is maintained by the gas molecules adsorbed in the pores, and the pore structure is not destroyed even when the porous powder is compressed. Therefore, the performance of the porous powder is not reduced compared to before compression molding, and excellent gas adsorption properties can be achieved. In one example of a method for producing a compression molded body, the gas adsorbed in the porous powder during compression molding is desorbed from the compression molded body by a process such as reducing the pressure inside the container to atmospheric pressure during compression molding or a subsequent process, resulting in a state where no gas molecules are present in the pores of the porous powder. Therefore, when the compression molded body obtained by the method for producing a compression molded body of the present invention is used as an adsorbent for a desired gas, the gas can be adsorbed into the pores of the porous powder, resulting in excellent gas adsorption properties. When the compression molded body is used as an adsorbent for a desired gas, the type of gas to be adsorbed can be appropriately selected depending on the type and average pore diameter of the porous powder constituting the compression molded body, but methane, carbon dioxide, hydrogen, etc. are preferred.Furthermore, air may be present in the container during the process of filling the container with the porous powder, and a gas other than air may be sealed in the container while air is present during the process of forming the compression-molded body. The critical temperature of oxygen, a component of air, is −118.6°C, and the critical temperature of nitrogen is −147°C. Therefore, when the process of forming the compression-molded body is performed at room temperature, the air component does not liquefy, and the air does not adversely affect the compression molding. The temperature inside the container during the process of forming the compression-molded body is preferably −57°C to 31°C, more preferably 0°C to 31°C. By keeping the temperature inside the container at −57°C to 31°C, if the gas sealed in the container is carbon dioxide, liquefaction of the carbon dioxide can be prevented. Furthermore, by keeping the temperature inside the container at 0°C to 31°C, moisture in the air can be prevented from freezing.

[0015] The porous powder is not particularly limited as long as it is a powder having a predetermined average pore size, such as micropores (e.g., an average pore size of 2 nm or less), mesopores (e.g., an average pore size of more than 2 nm and less than 50 nm), or macropores (e.g., an average pore size of more than 50 nm). The porous powder may be at least one type of porous powder selected from the group consisting of porous powders having micropores, porous powders having mesopores, and porous powders having macropores. The average pore size of the porous powder is preferably 50 nm or less, more preferably 2 nm to 50 nm. The porous powder is preferably a porous powder having a high specific surface area, and is preferably selected from metal organic frameworks (MOFs), activated carbon, and zeolites, which have a highly regular structure composed of metal ions and organic ligands. The metal organic framework is not particularly limited, but examples include HKUST1, HKUST1GO, Ni-MOF-74, and MOF-177. HKUST1 has a specific surface area of ​​approximately 1000 to 2300 m ２ / g, pore volume of about 0.70 to 0.88 cm ３ / g, true density is 1.62 g / cm ３ HKUST1GO is a metal organic framework with excellent adsorption properties for gases such as methane. ２ / g, pore volume of about 0.70 to 1.00 cm ３ / g, true density is 1.79 g / cm ３ Ni-MOF-74 is a metal organic framework with excellent adsorption properties for gases such as methane. Ni-MOF-74 has a specific surface area of ​​approximately 800 to 1400 m ２ / g, pore volume of about 0.50 to 0.75 cm ３ / g, true density is 1.89 g / cm ３ MOF-177 is a metal organic framework with excellent adsorption properties for gases such as methane at low pressures. ２ / g, pore volume of about 1.30 to 1.70 cm ３ / g, true density is 1.53 g / cm ３ This metal-organic framework has excellent adsorption properties for gases such as methane under high pressure.

[0016] The gas to be sealed in the container and adsorbed by the porous powder in the process of forming the compression molded body is not particularly limited as long as it is an inert gas that does not react with the porous powder or the container and is different from nitrogen and oxygen, and carbon dioxide (CO ２ ), ethane, etc., but carbon dioxide (CO ２ ) is preferred. ２ is a gas that is inert to the porous powder and the container, and is easy to obtain and handle, so it can be easily used in the process of forming a compression molded body.

[0017] In the process of forming the compression molded body, it is preferable to store the gas desorbed from the compression molded body in a buffer chamber connected to the container. Desorption of the gas adsorbed in the compression molded body may be performed simultaneously with the process of forming the compression molded body, or may be performed after the process of forming the compression molded body. By desorbing the gas adsorbed in the compression molded body from the compression molded body, gas molecules are no longer present in the pores of the porous powder constituting the compression molded body. Therefore, when the compression molded body is used as an adsorbent for a desired gas, the gas can be adsorbed in the pores of the porous powder, and the compression molded body can have excellent gas adsorption properties. In this case, the gas to be adsorbed is preferably methane or the like.

[0018] The buffer chamber that stores the gas desorbed from the compression-molded body is a separate chamber that communicates with the container, and has a volume ratio of (buffer chamber volume) / (container volume) of, for example, 1000:1 relative to the volume of the container. This allows for sufficient storage of the desorbed gas. The buffer chamber will be described later with reference to FIG. 2.

[0019] Gas is CO ２ In the step of forming the compression molded body, ２ It is preferable to compress the porous powder so that the pressure is 1.0 to 7.0 MPa, which is less than the critical pressure. ２ The pressure is more preferably 3.5 to 7.0 MPa. ２ By keeping the pressure within the above range, the porous powder can be sufficiently compressed to a density close to the true density. ２ The critical temperature of ethane is 31.1°C and the critical pressure is 7.4 MPa. When the gas is ethane, in the step of forming a compression-molded body, it is preferable to compress the porous powder so that the pressure of ethane is 2.0 to 4.5 MPa, which is less than the critical pressure. The pressure of ethane is more preferably 3.0 to 4.5 MPa, and even more preferably 3.5 to 4.5 MPa. By keeping the ethane pressure within the above range, the porous powder can be sufficiently compressed to a density close to the true density. The critical temperature of ethane is 305.4 K (32.3°C) and the critical pressure is 4.9 MPa.

[0020] An embodiment of the present invention will be described below with reference to the drawings. In the following description, for example, reference numerals in the drawings corresponding to the components of the invention are given in parentheses. It should be noted that the drawings are schematic, and the layout of each component, data format, communication method, etc. may differ from reality.

[0021] FIG. 1 is a diagram showing a method for producing a compression-molded body according to one embodiment of the present invention. As shown in FIG. 1( a), a porous powder 4 is filled into a container 3 that is open to atmospheric pressure, and then a piston 2 is inserted into the container 3. The porous powder 4 can be a metal-organic framework (MOF), activated carbon, or zeolite. The piston 2 is movable in the left-right direction shown in FIG. 1( a) within the container 3, and while the piston 2 is inserted into the container 3, the container is kept airtight. Next, the gas inlet pipe 6 is opened, and a gas 5 is sealed into the container 3 through the gas inlet pipe 6 at a predetermined pressure, causing the gas 5 to be adsorbed by the porous powder 4. An example of the gas 5 is carbon dioxide (CO ２ After the gas 5 has been sealed in for a predetermined time, the gas inlet pipe 6 is closed.

[0022] 1(b), the piston 2 is moved in the direction of the arrow to apply a compressive force to the porous powder 4, compressing the porous powder 4 and forming a compression-molded body of the porous powder 4. At this time, the gas 5 in the container 3 satisfies either of the following conditions: (1) the temperature of the gas 5 is equal to or higher than the critical temperature; or (2) the temperature of the gas 5 is below the critical temperature and the pressure of the gas 5 is below the critical pressure. Therefore, the gas 5 is not liquefied in the container 3, and the gas 5 previously sealed in the container 3 in the step of FIG. 1(a) is adsorbed into the pores of the porous powder 4. Therefore, even when the porous powder 4 is compressed in the step of FIG. 1(b), the pores of the porous powder 4 are prevented from clogging. As a result, the obtained compression-molded body can have a large specific surface area and pore volume similar to those of the porous powder 4, and can achieve a higher packing density than the porous powder 4. Therefore, the compression-molded body can have excellent gas adsorption properties for the desired gas. If a sufficient amount of time passes without any change in the pressure and temperature inside the container 3, the gas 5 reaches an adsorption equilibrium state with respect to the porous powder 4 inside the container 3. During compression molding, it is possible that some of the gas 5 adsorbed to the porous powder 4 will desorb. In this case, the desorbed gas 5 will increase the pressure inside the container 3. When the pressure 5 inside the container 3 increases in this way, the adsorption of the gas 5 to the porous powder 4 is promoted. As a result, even if some of the gas 5 desorbs from the porous powder 4, a new adsorption equilibrium state is formed due to the increase in pressure inside the container 4 caused by the desorbed gas 5, and a sufficient amount of gas is adsorbed into the pores of the porous powder 4. If it is desirable to avoid a sudden increase in pressure inside the container 3 during compression molding, or if it is desired to effectively prevent the gas pressure from exceeding the critical pressure during compression molding, the gas inlet pipe 6 may be opened while the piston 2 is moving in the direction of the arrow to discharge the gas that may be desorbed from the porous powder 4 through the gas inlet pipe 6.

[0023] FIG. 2 is a diagram illustrating a method for producing a compression-molded body according to another embodiment of the present invention. The compression molding apparatus 1 of FIG. 2 differs from the compression molding apparatus 1 of FIG. 1 in that it further includes a buffer chamber 7. In the method for producing a compression-molded body using the compression molding apparatus 1 of FIG. 2, as shown in FIG. 2(b), it is possible that a portion of the gas 5 adsorbed on the porous powder 4 may desorb from the porous powder 4 when the porous powder 4 is compressed by the piston 2. Even in such a case, the desorbed gas 5 can be contained in the buffer chamber 7, thereby minimizing pressure changes within the container 3 during compression of the porous powder 4. Furthermore, the pressure of the gas 5 can be effectively prevented from exceeding the critical pressure. Therefore, adverse effects on the container 3 and the compression-molded body due to large pressure fluctuations can be prevented. The volume of the buffer chamber 7 is not particularly limited, but can be, for example, 1,000 times the volume of the compression-molded body to effectively minimize pressure changes within the container 3. Note that the gas inlet pipe 6 may be opened while the piston 2 is moving in the direction of the arrow during compression molding, allowing gas that may desorb from the porous powder 4 to be discharged through the gas inlet pipe 6.

[0024] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0025] The porous powder HKUST1 was synthesized according to the method described in N. C. Jeong, B. Samanta, et al., "Coordination-Chemistry Control of Proton Conductivity in the Iconic Metal-Organic Framework Material HKUST-1," J. Am. Chem. Soc., 2012, 134, 51-54. The specific synthesis method for HKUST1 is described below. Distilled water, ethanol, and dimethylformamide were mixed in a 1:1:1 ratio to obtain a mixture. Next, copper(II) nitrate trihydrate and 1,3,5-benzenetricarboxylic acid were added to the mixture in a 1.8:1 ratio, and the mixture was stirred for half a day. The prepared solution was heated in a polyethylene container at 80°C for 24 hours. The synthesized crystals were then washed with ethanol and dried in a dryer at 80°C for 10 hours to synthesize the porous powder HKUST1. The true density of HKUST1 was 1.65 g / cm ３ The packing density of the uncompressed bulk HKUST1 is 0.30 g / cm ３ The porous powder HKUST1GO was synthesized according to the method described in A. Rosado, A. Borras et al., "HKUST-1 Metal-Organic Framework Nanoparticle / Graphene Oxide Nanocomposite Aerogels for CO2 and CH4 Adsorbent and Separation," ACS Appl. Nano Mater. 2021, 4, 12712-12725. The specific synthesis method for HKUST1GO is described below. Graphene oxide was dissolved in ethanol to a concentration of 4 mg / ml, and 0.3 g of HKUST1 crystals was added to 8.36 mL of the graphene oxide solution and stirred. The synthesized crystals were then washed with ethanol and dried at 80°C for 10 hours to obtain porous powder HKUST1GO. The true density of HKUST1GO was 1.79 g / cm ３ The packing density of uncompressed bulk HKUST1GO is 0.44 g / cm ３ It was.

[0026] (Examples 1 to 4) As shown in Fig. 2(a), the container 3 of the compression molding device 1 was filled with HKUST1, which is a porous powder 4, in the presence of air under atmospheric pressure. The gas inlet pipe 6 was opened, and carbon dioxide (CO ２ ) gas 5 is sealed in the container 3, and carbon dioxide (CO ２ The pressure of the carbon dioxide (CO ) gas 5 was set to the value shown in Table 1. After that, the gas inlet pipe 6 was closed and kept as it was for a predetermined time, thereby allowing the carbon dioxide (CO ) gas to enter the porous powder 4. ２ As shown in FIG. 2( b ), carbon dioxide (CO ) gas 5 was adsorbed on the porous powder 4. ２ ) With the gas 5 adsorbed, the piston 2 is pushed in the direction of the arrow to compress the porous powder 4, so that the packing density becomes approximately 1.2 g / cm ３ When compressing the porous powder 4, the gas inlet pipe 6 was opened to allow the carbon dioxide (CO ２ ) gas 5 is discharged from the container 3. ２ ) gas 5 pressure is made less than the critical pressure, and carbon dioxide (CO ２ ) Gas 5 was prevented from liquefying.

[0027] (Comparative Example 1) Carbon dioxide (CO ２ ) A compression molded body was formed in the same manner as in Examples 1 to 4, except that Gas 5 was not enclosed.

[0028] Reference Example 1 in Table 1 represents bulk HKUST1 that has not been subjected to compression molding. ２ Compared to Comparative Example 1 in which no carbon dioxide (CO ) gas 5 was sealed, ２ It can be seen that Examples 1 to 4 in which carbon dioxide (CO 2 ) gas 5 was sealed in the container 3 had a larger pore volume. ２ ) It can be seen that the higher the gas pressure, the larger the specific surface area and pore volume.

[0029] (Examples 5 to 8) The porous powder 4 was HKUST1GO, and carbon dioxide (CO ２) gas 5 when carbon dioxide (CO ２ A compression molded body was formed in the same manner as in Examples 1 to 4, except that the pressure of the carbon dioxide (CO ) gas 5 was changed to the pressure shown in Table 2. ２ ) gas 5 pressure is made less than the critical pressure, and carbon dioxide (CO ２ ) Gas 5 was prevented from liquefying.

[0030] (Comparative Example 2) Carbon dioxide (CO ２ ) Compression molded bodies were formed in the same manner as in Examples 5 to 8, except that Gas 5 was not enclosed.

[0031] Reference Example 2 in Table 2 shows bulk HKUST1GO that has not been subjected to compression molding. ２ Compared with Comparative Example 2 in which no carbon dioxide (CO ) gas 5 was sealed, ２ It can be seen that Examples 5 to 8 in which carbon dioxide (CO 2 ) gas 5 was sealed in the container 3 before compression molding had a larger pore volume. ２ ) It can be seen that the higher the pressure of gas 5, the larger the specific surface area and pore volume.

[0032] 3 and 4 are graphs showing methane adsorption isotherms of compression-molded bodies formed using HKUST1 and HKUST1GO as the porous powder and carbon dioxide as the filling gas, respectively. The methane adsorption isotherms of the compression-molded bodies were measured by volumetric method using a BELSORP HP (Microtrac). As shown in FIG. 3 , in the absolute pressure range of 0 to 7 MPa (horizontal axis) of the methane adsorption isotherm of HKUST1, the compression-molded body of Example 4 exhibited a high methane adsorption amount comparable to that of the bulk porous powder of Reference Example 1. The methane adsorption amount decreased in the order of Examples 4, 3, 2, and 1, but was much higher than that of the compression-molded body of Comparative Example 1. Similarly, as shown in FIG. 4 , the compression-molded body of Example 8 exhibited a high methane adsorption amount comparable to that of the bulk porous powder of Reference Example 2. The methane adsorption amount decreased in the order of Examples 8, 7, 6, and 5, but was much higher than that of the compression-molded body of Comparative Example 2. This is thought to be because in the compression molded bodies of Examples 4 and 8, a sufficient amount of carbon dioxide was adsorbed into the porous powder during compression molding, so that clogging of the pores of the porous powder did not occur.

[0033] 5 and 6 are diagrams showing estimated values ​​of the methane storage capacity of the compression molded bodies of Examples 1 to 4, Reference Example 1, and Comparative Example 1, and the compression molded bodies of Examples 5 to 8, Reference Example 2, and Comparative Example 2, respectively. The methane storage capacity of the compression molded body was calculated according to the following formula (1) in accordance with the method described in Kimberly R. Matranga, Alan L. Myers, Eduardo D. Grandt, "Storage of natural gas by adsorption on activated carbon," Chemical Engineering Science, 47, 1569-1579, 1992. In addition, each symbol in the above formula has the following meaning: ＊ : methane storage amount [cm 3 ] of the compression molded body at temperature T ３ / cm ３ a: methane adsorption amount of porous powder at temperature T [cm ３ / g] Vm: molar volume 22400 [cm ３ / mol] P: methane storage pressure [MPa] P ０ : atmospheric pressure 0.101325 [MPa] T: methane storage temperature [K] T ０ : Standard temperature 288.71 [K] Z: Compression coefficient at pressure P of methane [-] ρ: True density of porous powder [g / cm ３ ]ρ Ｂ : Packing density of porous powder [g / cm ３ ] R: Gas constant 8.314

[0034] As shown in Figure 5, all of Examples 1 to 4 exhibited higher methane storage capacities than Reference Example 1 and Comparative Example 1. Similarly, as shown in Figure 6, all of Examples 5 to 8 exhibited higher methane storage capacities than Reference Example 2 and Comparative Example 2. This is thought to be because the compression-molded bodies of Examples 1 to 8 exhibited higher methane storage capacities because the packing density of the porous powder was higher than that of bulk porous powder, and the pores in the porous powder were not blocked during compression molding.

[0035] (Examples 9 to 12) Carbon dioxide (CO ２ ) The pressure of the gas 5 was changed to the pressure shown in Table 3, and the packing density of the porous powder 4 was set to 1.50 g / cm ３ A compression molded body was formed in the same manner as in Examples 5 to 8, except that the carbon dioxide (CO ２ ) gas 5 pressure is made less than the critical pressure, and carbon dioxide (CO ２ ) Gas 5 was prevented from liquefying.

[0036] (Comparative Example 3) Carbon dioxide (CO ２ ) Compression molded bodies were formed in the same manner as in Examples 9 to 12, except that Gas 5 was not enclosed.

[0037] In Table 3, Reference Example 3 represents bulk HKUST1GO that has not been subjected to compression molding. According to Examples 9 to 12 in Table 3, the carbon dioxide (CO ２ ) It can be seen that the higher the pressure of gas 5, the larger the specific surface area and pore volume.

[0038] FIG. 7 shows the methane adsorption isotherms of compression-molded bodies formed using HKUST1GO of Examples 9 to 12 as the porous powder and carbon dioxide as the filling gas. The methane adsorption isotherms of the compression-molded bodies were measured using the same method as in Examples 1 to 8. As shown in FIG. 7, in the absolute pressure range of 0 to 7 MPa (horizontal axis) of the methane adsorption isotherm, the compression-molded body of Example 12 exhibited a high methane adsorption amount similar to that of the bulk porous powder of Reference Example 3. The methane adsorption amount decreased in the order of Examples 12, 11, 10, and 9, but was much higher than that of the compression-molded body of Comparative Example 3. This is thought to be because a sufficient amount of carbon dioxide was adsorbed into the porous powder during compression molding in the compression-molded body of Example 12, preventing blockage of the pores of the porous powder.

[0039] FIG. 8 is a diagram showing estimated values ​​of methane storage capacity of the compression-molded porous powder bodies of Examples 9 to 12. The methane storage capacity of the compression-molded bodies was calculated according to the above formula (1). Among Examples 9 to 12, the compression-molded body of Example 12 exhibited the highest methane storage capacity. Although the methane storage capacity decreased in the order of Examples 12, 11, 10, and 9, all of Examples 9 to 12 exhibited higher methane storage capacity than Reference Example 3 and Comparative Example 3. In particular, the compression-molded body of Example 12 exhibited the highest methane storage capacity because the packing density of the porous powder was higher than that of the bulk porous powder, and the pores in the porous powder were not blocked during compression molding.

[0040] (Examples 13 to 18) Compression-molded bodies were formed in the same manner as in Examples 1 to 8, except that the porous powders shown in Table 4 were used, the pressure of the gas sealed in the container 3 before compression molding was changed to the pressure shown in Table 4, and ethane was used as the filler gas instead of carbon dioxide. During compression molding, the pressure of the ethane in the container 3 was kept below the critical pressure to prevent the ethane from liquefying.

[0041] In Table 4, Reference Examples 4, 5, and 6 represent bulk HKUST1, HKUST1GO, and MOF-177, respectively, that were not subjected to compression molding. Examples 13 to 18 in Table 4 show that the higher the pressure of ethane sealed in container 3 before compression molding, the larger the specific surface area and pore volume.

[0042] FIG. 9 is a graph showing methane adsorption isotherms of compression-molded bodies formed using HKUST1 of Reference Example 4 and Examples 13-14 as the porous powder and ethane as the filling gas. The methane adsorption isotherms of the compression-molded bodies were measured in the same manner as in Examples 1-8. As shown in FIG. 9, in the absolute pressure range of 0 to 7 MPa (horizontal axis) of the methane adsorption isotherm, the compression-molded body of Example 14 exhibited a high methane adsorption amount similar to that of the bulk porous powder of Reference Example 4. The methane adsorption amount decreased in the order of Examples 14 and 13. This is thought to be because, in the compression-molded body of Example 14, a sufficient amount of ethane was adsorbed to the porous powder during compression molding, so clogging of the pores of the porous powder did not occur.

[0043] FIG. 10 is a diagram showing estimated values ​​of the methane storage capacity of the compression-molded bodies of Reference Example 4 and Examples 13-14. The methane storage capacity of the compression-molded bodies was calculated according to the above formula (1). Among Examples 13-14, the compression-molded body of Example 14 exhibited the highest methane storage capacity. Although the methane storage capacity decreased in the order of Examples 14 and 13, all of Examples 13-14 exhibited higher methane storage capacity than Reference Example 4. In particular, the compression-molded body of Example 14 exhibited the highest methane storage capacity because the packing density of the porous powder was higher than that of the bulk porous powder, and no clogging of the pores in the porous powder occurred during compression molding.

[0044] FIG. 11 is a graph showing methane adsorption isotherms for compression-molded bodies formed using HKUST1GO of Reference Example 5 and Examples 15-16 as the porous powder and ethane as the filling gas. The methane adsorption isotherms for the compression-molded bodies were measured in the same manner as in Examples 1-8. As shown in FIG. 11, in the absolute pressure range of 0 to 7 MPa (horizontal axis) of the methane adsorption isotherm, the compression-molded body of Example 16 exhibited a high methane adsorption amount similar to that of the bulk porous powder of Reference Example 5. The methane adsorption amount decreased in the order of Examples 16 and 15. This is thought to be because, in the compression-molded body of Example 16, a sufficient amount of ethane was adsorbed to the porous powder during compression molding, so clogging of the pores of the porous powder did not occur.

[0045] FIG. 12 is a diagram showing estimated values ​​of the methane storage capacity of the compression-molded bodies of Reference Example 5 and Examples 15-16. The methane storage capacity of the compression-molded bodies was calculated according to the above formula (1). Among Examples 15-16, the compression-molded body of Example 16 exhibited the highest methane storage capacity. Although the methane storage capacity decreased in the order of Examples 16 and 15, all of Examples 15-16 exhibited higher methane storage capacity than Reference Example 5. In particular, the compression-molded body of Example 16 exhibited the highest methane storage capacity because the packing density of the porous powder was higher than that of the bulk porous powder, and the pores in the porous powder were not blocked during compression molding.

[0046] FIG. 13 is a diagram showing the methane adsorption isotherms of compression-molded bodies formed using MOF-177 of Reference Example 6 and Examples 17-18 as the porous powder and ethane as the filling gas. The methane adsorption isotherms of the compression-molded bodies were measured in the same manner as in Examples 1-8. As shown in FIG. 13, in the absolute pressure range of 0 to 7 MPa (horizontal axis) of the methane adsorption isotherm, the compression-molded body of Example 18 exhibited a high methane adsorption amount similar to that of the bulk porous powder of Reference Example 6. The methane adsorption amount decreased in the order of Examples 18 and 17 for the compression-molded body. This is thought to be because in the compression-molded body of Example 18, a sufficient amount of ethane was adsorbed to the porous powder during compression molding, so clogging of the pores of the porous powder did not occur.

[0047] FIG. 14 is a diagram showing estimated values ​​of the methane storage capacity of the compression-molded bodies of Reference Example 6 and Examples 17 to 18. The methane storage capacity of the compression-molded bodies was calculated according to the above formula (1). Among Examples 17 to 18, the compression-molded body of Example 18 exhibited the highest methane storage capacity. Although the methane storage capacity decreased in the order of Examples 18 and 17, all of Examples 17 to 18 exhibited higher methane storage capacity than Reference Example 6. In particular, the compression-molded body of Example 18 exhibited the highest methane storage capacity because the packing density of the porous powder was higher than that of the bulk porous powder, and the pores in the porous powder were not blocked during compression molding.

[0048] (Examples 19 to 20) Compression-molded bodies were formed in the same manner as in Examples 1 to 8, except that activated carbon, which was an AX-21 molded body, was used as the porous powder, the pressure of the gas sealed in the container 3 before compression molding was changed to the pressure shown in Table 5, and ethane was used instead of carbon dioxide as the filler gas. During compression molding, the pressure of the ethane in the container 3 was kept below the critical pressure to prevent the ethane from liquefying.

[0049] In Table 5, Reference Example 7 represents activated carbon that is a bulk AX-21 molded body that has not been subjected to compression molding. Examples 19 and 20 in Table 5 show that the pore volume increases as the pressure of ethane sealed in container 3 before compression molding increases.

[0050] FIG. 15 is a graph showing the methane adsorption isotherms of compression-molded bodies formed using activated carbon, which is the AX-21 molded body of Reference Example 7 and Examples 19-20, as the porous powder and ethane as the filling gas. The methane adsorption isotherms of the compression-molded bodies were measured in the same manner as in Examples 1-8. As shown in FIG. 15, in the absolute pressure range of 0 to 7 MPa (horizontal axis) of the methane adsorption isotherm, the compression-molded body of Example 20 exhibited a high methane adsorption amount similar to that of the bulk porous powder of Reference Example 7. The methane adsorption amount decreased in the order of Examples 20 and 19. It is thought that in the compression-molded body of Example 20, a sufficient amount of ethane was adsorbed to the porous powder during compression molding, so clogging of the pores of the porous powder did not occur.

[0051] FIG. 16 is a diagram showing estimated values ​​of the methane storage capacity of the compression molded bodies of Reference Example 7 and Examples 19-20. The methane storage capacity of the compression molded bodies was calculated according to the above formula (1). Among Examples 19-20, the compression molded body of Example 20 exhibited the highest methane storage capacity. Although the methane storage capacity decreased in the order of Examples 20 and 19, all of Examples 19-20 exhibited higher methane storage capacity than Reference Example 7. In particular, the compression molded body of Example 20 exhibited the highest methane storage capacity because the packing density of the porous powder was higher than that of the bulk porous powder, and the pores in the porous powder were not blocked during compression molding.

[0052] As described above, in the method for producing a compression-molded body of the present invention, by compressing the porous powder in a state in which the porous powder adsorbs a gas, it was confirmed that the porous powder constituting the compression-molded body does not become clogged and has high methane adsorption properties. Furthermore, because the packing density of the porous powder can be increased by compression molding, it was confirmed that the compression-molded body produced by the method for producing a compression-molded body of the present invention has a high methane storage capacity.

[0053] 1... compression molding device, 2... piston, 3... container, 4... porous powder, 5... gas, 6... gas introduction pipe, 7... buffer chamber

Claims

1. A method for manufacturing a compression molded body, comprising the steps of: filling a container with porous powder; and, with a gas sealed in the container and the porous powder adsorbing the gas, compressing the porous powder to form a compression molded body so as to satisfy the following condition (1) or (2): (1) the temperature of the gas is equal to or higher than the critical temperature; or (2) the temperature of the gas is lower than the critical temperature and the pressure of the gas is lower than the critical pressure.

2. The method for producing a compression-molded body according to claim 1, wherein the porous powder is selected from the group consisting of a metal-organic framework (MOF), activated carbon, and zeolite.

3. The gas is CO ２ The method for producing a compression-molded body according to claim 1 or 2, wherein the solvent is selected from the group consisting of ethane and ethane.

4. A method for producing a compression molded body as described in claim 1 or 2, wherein in the process of forming the compression molded body, the gas desorbed from the compression molded body is stored in a buffer chamber connected to the container.

5. The gas is CO ２ In the step of forming the compression molded body, ２ The method for producing a compression-molded body according to claim 1 or 2, wherein the porous powder is compressed so that the pressure is 1.0 to 7.0 MPa.

6. The method for producing a compression-molded body according to claim 1 or 2, wherein the gas is ethane, and in the step of forming the compression-molded body, the porous powder is compressed so that the pressure of the ethane is 2.0 to 4.5 MPa.

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