Carbon dioxide recovery material

Abstract

The present invention provides a carbon dioxide recovery material that can reduce the amount of thermal energy required for the desorption of absorbed carbon dioxide. [Solution] This carbon dioxide recovery material 1 has a carbon dioxide absorbent 13 supported on the surface of a columnar honeycomb structure 10. The honeycomb structure 10 is a porous molded body formed mainly from silica particles 15 in which a plurality of pores 15a are formed, and is porous due to the pores 15a. The carbon dioxide absorbent is an amine compound. The carbon dioxide absorbent is further supported on the wall surface 15b of the pores 15a, leaving spaces S formed by the pores 15a.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide recovery material for recovering carbon dioxide.

Background Art

[0002] As a technique of this type, for example, Patent Document 1 proposes a honeycomb structure for gas adsorption comprising a wall portion containing a plurality of ceramic particles. Patent Document 1 exemplifies zeolite, silica, cerium oxide, alumina, zirconia, magnesia and the like as ceramic particles.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Here, when the honeycomb structure disclosed in, for example, Patent Document 1 is used as a carbon dioxide recovery material, the honeycomb structure is caused to support a carbon dioxide absorbent composed of an amine compound. The carbon dioxide absorbent is difficult to directly support on a honeycomb structure having the above-described composition, and is easily supported on silica. Therefore, when producing a carbon dioxide recovery material, it is assumed that after silica particles are supported on the surface of the honeycomb structure or the surface of the honeycomb structure is coated with silica, the silica is further caused to support the carbon dioxide absorbent.

[0005] Incidentally, when recovering carbon dioxide from carbon dioxide recovery materials, the materials are heated to release the absorbed carbon dioxide from the carbon dioxide absorbent. However, it is difficult to heat only the carbon dioxide absorbent, which has absorbed the carbon dioxide, to the desorption temperature at which the carbon dioxide is released. Therefore, the honeycomb structure must also be heated to near the desorption temperature. As a result, there is a risk that the amount of thermal energy supplied to the carbon dioxide recovery material for carbon dioxide release will be excessive.

[0006] The present invention has been made in view of these points, and its objective is to provide a carbon dioxide recovery material that can reduce the amount of thermal energy required to desorb absorbed carbon dioxide. [Means for solving the problem]

[0007] In view of the above problems, the carbon dioxide recovery material according to the present invention is a carbon dioxide recovery material in which a carbon dioxide absorbent is supported on the surface of a columnar honeycomb structure, wherein the honeycomb structure is formed mainly from silica particles having a plurality of pores and is a porous molded body that is porous due to the pores, the carbon dioxide absorbent is an amine compound, and the carbon dioxide absorbent is further supported on the walls of the pores such that spaces formed by the pores remain. [Effects of the Invention]

[0008] According to the carbon dioxide recovery material of the present invention, the honeycomb structure is formed using silica particles with multiple pores as the main material, and is a porous molded body that is porous due to the pores. As a result, the amine compound, which is a carbon dioxide absorbent, can be directly supported on the honeycomb structure. As a result, compared to conventional honeycomb structures, the amount of thermal energy that needs to be supplied to the carbon dioxide recovery material when the absorbed carbon dioxide is released from the carbon dioxide absorbent can be reduced. [Brief explanation of the drawing]

[0009] [Figure 1](a) is a schematic perspective view of a carbon dioxide recovery material according to an embodiment of the present invention. (b) is a schematic enlarged cross-sectional view of a partition wall of a honeycomb structure constituting the carbon dioxide recovery material shown in (a). (c) is a schematic enlarged view of part A shown in (b). [Figure 2] This graph shows the relationship between the pore diameter and log differential pore volume of the honeycomb structure according to Examples 1-1 to 1-3. [Figure 3] This graph shows the relationship between the amount of amine compound supported by the carbon dioxide recovery material in Examples 1-1 to 1-3 and the amount of carbon dioxide removed. [Figure 4] This graph shows the A-axis compressive strength of the carbon dioxide recovery material used in Examples 2-1 to 2-4. [Figure 5] This graph shows the relationship between the A-axis compressive strength of the honeycomb structure of the carbon dioxide recovery material in Examples 2-1, 2-3, and 2-4 and the amount of carbon dioxide desorbed from the carbon dioxide recovery material. [Figure 6] (a) to (c) are graphs showing the relationship between the heat treatment temperature of silica powders in Reference Examples 1 to 3 and Reference Comparative Examples, and pore diameter, pore volume, or specific surface area. [Modes for carrying out the invention]

[0010] The carbon dioxide capture material according to this embodiment will be described below with reference to Figure 1. As shown in Figure 1, in this embodiment, the carbon dioxide recovery material 1 is a carbon dioxide recovery material in which a carbon dioxide absorbent is supported on the surface of a columnar honeycomb structure 10. Specifically, the columnar honeycomb structure 10 has a cylindrical outer wall 11 and partition walls 12 formed in a grid pattern inside the outer wall 11.

[0011] The outer perimeter wall 11 and the partition wall 12 are formed integrally, and the partition wall 12 extends along the axial direction of the outer perimeter wall 11. Hereinafter, the axial direction of the outer perimeter wall 11 will be referred to as the A-axis direction of the carbon dioxide recovery material 1 (honeycomb structure 10), and the line along this direction will be referred to as the A-axis. In this embodiment, by providing such a partition wall 12, a plurality of gas flow channels 14 with a rectangular cross-section are formed in the honeycomb structure 10 along the A-axis direction.

[0012] In this embodiment, the honeycomb structure 10 is a porous molded body formed primarily from silica particles 15 having a plurality of pores 15a, and is porous due to the pores 15a. Specifically, the honeycomb structure 10 consists of silica particles 15 and an inorganic binder (not shown) such as colloidal silica that binds the silica particles 15 together, and the silica particles 15 are exposed on the surface 12a of the partition wall 12. The pores 15a of the silica particles 15 are exposed on the surface 12a of the partition wall 12, and the silica constituting the silica particles 15 is exposed on the wall surface 15b that forms the pores 15a. In addition, through holes may be formed in the partition wall 12 by the pores 15a of the plurality of silica particles 15.

[0013] The silica particles 15 are not particularly limited as long as they can form multiple pores 15a. For example, the silica particles 15 can be particles made of silica gel, or particles made of mesoporous silica with mesopores formed on them. Silica particles 15 made of mesoporous silica have a larger specific surface area than those made of silica gel, and therefore can improve the carbon dioxide recovery efficiency (absorption efficiency) described later. Since the silica particles 15 are commercially available silica particles that are generally known, a detailed explanation of their manufacturing method will be omitted.

[0014] The honeycomb structure 10 can be manufactured as follows. First, a raw material composition containing silica powder including silica particles 15 serving as a ceramic raw material, a dispersion medium such as water, and an inorganic binder is kneaded to prepare a kneaded clay, and then the kneaded clay is extruded and dried, whereby the honeycomb structure 10 can be manufactured. In the drying step, for example, a conventionally known drying method such as hot air drying can be used. The honeycomb structure 10 after drying may be further fired. For example, in the firing step, the firing temperature described later may be set within a range of 500°C to 900°C.

[0015] The honeycomb structure 10 preferably has the following physical properties: (1) pore diameter: 10 to 50 nm, (2) pore volume: 1.00 to 1.40 mL / g, (3) specific surface area: 90 to 330 m 2 / g, and (4) A-axis compressive strength: 9 to 12 MPa. Items (1) to (3) can be adjusted by setting the type of silica particles 15 to be selected and the heat treatment temperature of the silica particles 15 (which may be the firing temperature of the honeycomb structure 10), and item (4) can be adjusted by setting the firing temperature of the honeycomb structure 10. These numerical ranges will be described in detail in the examples mentioned later.

[0016] The carbon dioxide absorbent 13 is supported on the surface of the honeycomb structure 10. Specifically, as shown in FIG. 1(b), the carbon dioxide absorbent 13 is supported on the surface 12a of the partition walls 12 of the honeycomb structure 10. Further, as shown in FIG. 1(c), the carbon dioxide absorbent 13 is further supported on the wall surface 15b of the pores 15a of the silica particles 15 so as to leave the space S formed by the pores 15a.

[0017] The carbon dioxide absorbent 13 is an amine compound that absorbs (adsorbs) carbon dioxide, and the type thereof is not limited. For example, the amine compound may be a primary amine or a secondary amine, and various amine compounds such as diethanolamine, pentaethylenehexamine, polyethyleneimine, tetraethylenepentamine, and monoethanolamine can be mentioned.

[0018] When supporting the carbon dioxide absorbent (13) on the honeycomb structure (10), after immersing the honeycomb structure (10) in an aqueous solution of the carbon dioxide absorbent (13), the immersed honeycomb structure (10) may be dried; alternatively, after immersing the honeycomb structure (10) in the carbon dioxide absorbent (13) itself, the immersed honeycomb structure (10) may be dried. A proportion of the carbon dioxide absorbent relative to a total mass of the carbon dioxide recovery material is preferably 10% by mass to 40% by mass. The proportion of the carbon dioxide absorbent can be adjusted by setting the concentration of the above-described aqueous solution of the carbon dioxide absorbent (13), immersion time, draining time of the carbon dioxide absorbent (13) during drying, and the like. These numerical ranges will be described in detail in the examples mentioned later.

[0019] According to the present embodiment, the honeycomb structure (10) is molded mainly from silica particles (15) formed with a plurality of pores (15a), so the carbon dioxide absorbent (13) which is an amine compound can be directly supported on the honeycomb structure (10). The carbon dioxide absorbent (13) is supported not only on the surface of the columnar honeycomb structure (the surface (12a) of the partition walls (12)), but also on the wall surfaces (15b) of the pores (15a) so as to leave a space S formed by the pores (15a).

[0020] Accordingly, carbon dioxide contained in gas flowing through the gas flow paths (14) can be absorbed not only by the carbon dioxide absorbent (13) supported on the surface of the columnar honeycomb structure (10) (the surface (12a) of the partition walls (12)), but also by the carbon dioxide absorbent (13) supported on the wall surfaces (15b) of the pores (15a) in the space S of the pores (15a). When recovering the absorbed carbon dioxide, the carbon dioxide recovery material (1) including the honeycomb structure (10) is heated to a desorption temperature at which carbon dioxide is desorbed from the carbon dioxide absorbent (13). In the present embodiment, the amine compound serving as the carbon dioxide absorbent (13) is directly supported on the honeycomb structure (10) mainly made of silica particles, so compared to a honeycomb structure that supports silica and a carbon dioxide absorbent, the amount of thermal energy that needs to be supplied to the carbon dioxide recovery material (1) can be reduced.

Examples

[0021] Examples of this embodiment will be described below.

[0022] [Examples 1-1 to 1-3] In Examples 1-1 to 1-3, three types of silica powder (G10, G30, and G50) containing silica particles (silica gel particles) with different pore sizes were prepared. Next, a clay base was prepared by kneading a raw material composition containing 100 parts by weight of silica powder, 200 parts by weight of water as a dispersion medium, 25 parts by weight of methylcellulose as an organic binder, and 15 parts by weight of colloidal silica as an inorganic binder. Three columnar honeycomb molded bodies were produced for each of Examples 1-1 to 1-3 by extrusion molding and drying. Next, the molded honeycomb molded bodies were fired at a firing temperature of 500°C to produce honeycomb structures. The pore size, pore volume, and specific surface area of ​​the honeycomb structures were measured using the methods shown in (A) and (B) below. The results are shown in Table 1.

[0023] [Table 1]

[0024] (A) Measurement of pore diameter and pore volume The pore size (nm) and pore volume (cc / g) in the honeycomb structure were measured using a mercury porosimometer (mercury intrusion method). A Micromeritics Auto Pore V, model 9605, was used as the mercury porosimometer. Specifically, a sample cut into a predetermined block shape (for example, a sample with sides of 10 mm) was placed in a measurement cell, mercury was introduced into the cell, and the total pore volume was measured from the volume of mercury intruded into the pores. Furthermore, the pore diameter at which the log differential pore volume (mL / g) measurement waveform peaked (mode pore diameter), as shown in Figure 2, was defined as the pore diameter.

[0025] (B) Measurement of specific surface area Measurements were taken using a mercury porosimeter, Micromeritics Auto Pore V, model 9605, on samples cut from a honeycomb structure into predetermined block shapes (for example, samples with sides of 10 mm).

[0026] Next, for each of Examples 1-1 to 1-3, polyethyleneimine (amine compound), a carbon dioxide absorbent, was supported on each honeycomb structure in proportions of 20% by mass, 30% by mass, and 40% by mass relative to the total carbon dioxide recovery material to prepare a carbon dioxide recovery material. When supporting the carbon dioxide absorbent on the honeycomb structure, the honeycomb structure was immersed in an aqueous solution of polyethyleneimine, the carbon dioxide absorbent, and then the immersed honeycomb structure was dried.

[0027] [Comparative Example 1] For Comparative Example 1, honeycomb structures similar to those in Example 1-1 were prepared. A carbon dioxide absorbent similar to that in Example 1-1 was loaded onto the prepared honeycomb structures at a concentration of 45% by mass to create a carbon dioxide recovery material. It was observed that the carbon dioxide absorbent overflowed from the pores of the carbon dioxide recovery material, filling the pores.

[0028] [Evaluation Test] In each of the carbon dioxide recovery materials in Examples 1-1 to 1-3, a gas containing carbon dioxide was supplied for a predetermined time, and the carbon dioxide absorbent was allowed to absorb the carbon dioxide. The increase in mass of the carbon dioxide recovery material before and after carbon dioxide absorption was measured, and the increase in weight was taken as the mass of carbon dioxide absorbed by the carbon dioxide absorbent. The mass of carbon dioxide was divided by the weight of the carbon dioxide absorbent, and this value was taken as the amount of carbon dioxide desorbed (percentage). The results are shown in Figure 3. Figure 3 is a graph showing the relationship between the amount of amine compound (carbon dioxide absorbent) loaded on the carbon dioxide recovery material in Examples 1-1 to 1-3 and the amount of CO2 desorbed (amount of carbon dioxide desorbed).

[0029] Furthermore, since the carbon dioxide recovery material in Comparative Example 1 has carbon dioxide absorbent filling its pores, we believe that its carbon dioxide absorption efficiency by the carbon dioxide absorbent is lower than that of Examples 1-1 to 1-3, and therefore, no evaluation tests were conducted.

[0030] [Result 1] As shown in Table 1 and Figure 3, (1) the pore diameter of the honeycomb structure is in the range of 10 to 50 nm (specifically 11 to 49 nm), (2) the pore volume of the honeycomb structure is in the range of 1.00 to 1.40 mL / g (specifically 1.05 to 1.35 mL / g), and (3) the specific surface area of ​​the honeycomb structure is 90 to 330 m². 2 / g (specifically 92-324m) 2 It is preferable that the pore size is within the range of ( / g). If it is within this range, it is easier to ensure that there is space for carbon dioxide to come into contact with the carbon dioxide absorbent within the pores, and thus the carbon dioxide absorption efficiency is ensured. Note that if the pore diameter is less than 10 nm, if the pore volume is less than 1.00 mL / g, the specific surface area is 90 m². 2 If the value is less than 1.40 mL / g, it is assumed that the surface area for the carbon dioxide absorbent to react with carbon dioxide is not sufficient, and the carbon dioxide absorption efficiency (adsorption efficiency) may not be sufficient. On the other hand, if the pore diameter exceeds 50 nm, if the pore volume exceeds 1.40 mL / g, and the specific surface area exceeds 330 m², 2 If the value exceeds [amount] / g, it is assumed that the pore size will become too large, potentially reducing the strength of the honeycomb structure.

[0031] Furthermore, as shown in Figure 3, if the conditions (1) to (3) of the honeycomb structure described above are met, the amount of CO2 desorption is thought to depend on the amount of amine compound supported (proportion of carbon dioxide absorbent). From Figure 3, it can be seen that the proportion of carbon dioxide absorbent to the total mass of the carbon dioxide recovery material should be 20% to 40% by mass, and furthermore, it is thought that a proportion of about 10% by mass of carbon dioxide absorbent is sufficient for the carbon dioxide absorbent to absorb a certain amount of carbon dioxide.

[0032] [Examples 2-1 to 2-4] In Examples 2-1 to 2-4, multiple carbon dioxide recovery materials were prepared in the same manner as in Example 1-1, with a carbon dioxide absorbent supported at a ratio of 30% by mass on the entire carbon dioxide recovery material. The difference between Examples 2-1 to 2-4 and Example 1-1 is that the honeycomb structures were fired at temperatures of 500°C, 700°C, 800°C, and 900°C, respectively. The A-axis compressive strength of the honeycomb structures in Examples 2-1 to 2-4 was measured using the method shown in (C) below. The results are shown in Table 2 and Figure 4 below.

[0033] [Table 2]

[0034] (C) Measurement of A-axis compressive strength The A-axis compressive strength [MPa] in the direction of the central axis of a honeycomb structure is the "A-axis compressive strength" specified in JASO standard M505-87, an automotive standard issued by the Society of Automotive Engineers of Japan. In this embodiment, the A-axis compressive strength of the honeycomb structure was measured using a dual-column benchtop universal test system (INSTRON, model 5569). A cylindrical sample with a length of 25.4 mm in the Z-axis direction and a diameter of 25.4 mm perpendicular to it was cut from the honeycomb structure. The compressive strength in the A-axis direction measured by the dual-column benchtop universal test system is the A-axis compressive strength. A compressive load was continuously and gradually applied in the direction of the central axis (A-axis direction), which is the flow direction of the sample, and the compressive load was increased until the pressure value at which the sample broke (= compressive load at the time of breakage / actual cross-sectional area of ​​the sample) was defined as the A-axis compressive strength [MPa].

[0035] Furthermore, the amount of CO2 desorption (amount of carbon dioxide desorption) was determined for each carbon dioxide recovery material in Examples 2-1, 2-3, and 2-4 using the same method as in Example 1-1. The results are shown in Figure 5. Figure 5 is a graph showing the relationship between the A-axis compressive strength of the honeycomb structure of the carbon dioxide recovery materials in Examples 2-1, 2-3, and 2-4 and the amount of carbon dioxide desorption from the carbon dioxide recovery material.

[0036] [Result 2] As shown in Table 2 and Figure 4, the A-axis compressive strength of Example 2-4 was found to be significantly improved compared to Examples 2-1 to 2-3. This is thought to be because the honeycomb structure of Example 2-4 contracted after firing at a firing temperature of 900°C, resulting in a denser microstructure. Based on the A-axis compressive strength results for Example 2-4 shown in Table 2, it can be said that the A-axis compressive strength of the honeycomb structure is preferably in the range of 9 to 12 MPa (specifically 9.8 to 11.3 MPa). If it is within this range, the strength of the carbon dioxide recovery material is significantly improved. Furthermore, as shown in Figure 5, the amount of CO2 desorption in Example 2-4 is almost the same as that of Example 2-3, and only slightly lower than that of Example 2-4. Therefore, even if the honeycomb structure is fired to achieve an A-axis compressive strength of 9 to 12 MPa, as in Example 2-4, a certain level of carbon dioxide absorption efficiency can be ensured.

[0037] In the following Reference Examples 1-3 and Reference Comparative Examples, the honeycomb structure shrank when the firing temperature was set to 900°C. Therefore, a confirmation test was conducted to determine how much the pores of the silica particles in the honeycomb structure became smaller.

[0038] [Reference Examples 1-3] In Reference Examples 1-3, silica powder (G10) equivalent to that used in Example 1-1 was prepared. In Reference Example 1, the silica powder was not heat-treated, while in Reference Examples 2 and 3, heat treatment was performed under the same firing conditions (firing temperature and firing time) as in Examples 2-3 and 2-4, respectively. Specifically, the silica powder in Reference Example 2 was heat-treated at 800°C, and the silica powder in Reference Example 3 was heat-treated at 900°C. The pore diameter, pore volume, and specific surface area of ​​the silica particles in the silica powders of Reference Examples 1-3 were measured. These results are shown in Table 3 and Figures 6(a)-(c). Note that, unlike the measurement method shown in Example 1-1, the pore diameter (mode pore diameter) and pore volume were measured using the BJH method (Barrett-Joyner-Halenda method). The specific surface area was measured using the BET method (Brunauer-Emmett-Teller method), unlike the measurement method shown in Example 1-1. Therefore, these values ​​for silica particles in silica powder are reference values ​​and should not be compared with the values ​​shown in Table 1, as they differ from the pore diameter, pore volume, and specific surface area values ​​measured for the honeycomb structure.

[0039] [Reference Comparison] In the comparative example, silica powder (G10) equivalent to that used in Reference Example 1 was prepared. The difference between the comparative example and the reference example is that the heat treatment temperature was set to 1000°C. The pore diameter, pore volume, and specific surface area of ​​the silica particles of the silica powder in the comparative example were measured using the same measurement method as in the reference example. These results are shown in Table 3 and Figures 6(a) to (c).

[0040] [Table 3]

[0041] [Result 3] Table 3 and Figures 6(a)-(c) also show that the pore diameter, pore volume, and specific surface area of ​​the reference comparative example are considerably smaller than those of reference examples 1-3. Therefore, it is considered that by using the honeycomb structure fired at 900°C as shown in Example 2-4 above, the pore characteristics of the silica particles can be secured to the same extent as those of honeycomb structures fired at lower temperatures. When silica powder is heat-treated (fired) at 1000°C as in the reference comparative example, the pore diameter, pore volume, and specific surface area become significantly smaller, which is thought to result in a trade-off where the amount of carbon dioxide absorbent that can be supported decreases.

[0042] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims. [Explanation of symbols]

[0043] 1: Carbon dioxide capture material, 10: Honeycomb structure, 13: Carbon dioxide absorbent, 15: Silica particles, 15a: Pores, 15b: Wall surface, S: Space

Claims

1. A carbon dioxide recovery material in which a carbon dioxide absorbent is supported on the surface of a columnar honeycomb structure, The aforementioned honeycomb structure is a porous molded body formed primarily from silica particles having multiple pores, and is porous due to these pores. The carbon dioxide absorbent is an amine compound, A carbon dioxide recovery material comprising the carbon dioxide absorbent, further supported on the walls of the pores such that the spaces formed by the pores remain.

2. The carbon dioxide recovery material according to claim 1, wherein the honeycomb structure has the following physical properties (1) to (4). (1) Pore diameter: 10-50nm (2) Pore volume: 1.00–1.40 mL / g (3) Specific surface area: 90-330 m² ２ / g (4) A-axis compressive strength: 9-12 MPa

3. The carbon dioxide recovery material according to claim 2, wherein the ratio of the carbon dioxide absorbent to the total mass of the carbon dioxide recovery material is 10% by mass to 40% by mass.

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