Solid recovery material for carbon dioxide and production method therefor

Abstract

This solid recovery material for carbon dioxide includes sodium, iron, and an aggregate, and includes holes with diameters of 0.05 μm or greater in cross-section. This solid recovery material for carbon dioxide can achieve both a carbon dioxide recovery quantity and a crushing strength.

Description

Solid carbon dioxide capture material and its manufacturing method

[0001] The present invention relates to a solid recovery material that fixes carbon dioxide and a method for producing the same, and more particularly to a solid recovery material containing sodium ferrite and a method for producing the same.

[0002] Research into the capture, storage, and utilization of carbon dioxide has been conducted to reduce the amount of carbon dioxide released into the atmosphere. Large-scale sources of carbon dioxide include thermal power plants, boilers in manufacturing plants, and kilns in cement plants, which use coal, heavy oil, or natural gas as fuel. Other sources include blast furnaces in steel plants, which reduce iron oxide with coke, and transportation vehicles such as automobiles, ships, and airplanes, which use gasoline, heavy oil, or light oil as fuel.

[0003] Patent Document 1 discloses a solid carbon dioxide recovery material containing 1% by weight to 99% by weight of sodium ferrite and 1% by weight to 99% by weight of a porous material. Examples of the porous material include activated carbon, porous clay minerals such as zeolite, porous silica, and activated alumina. It also discloses that when the porosity of the porous material exceeds 50%, the specific surface area of ​​the solid recovery material, i.e., the contact area with carbon dioxide, increases, thereby improving the carbon dioxide absorption rate, and that when the porosity is 70% or less, good carbon dioxide capture performance can be obtained. A preferred range for the specific surface area of ​​the solid recovery material is 5 m ２ / g to 500m ２ / g is listed.

[0004] Furthermore, Patent Document 1 discloses a method for producing a solid recovery material, which includes a step of reacting a material containing iron oxide with an alkaline compound containing sodium in the presence of a porous material. It is described that this method makes it possible to support a large amount of sodium ferrite on the surface of the porous material.

[0005] Patent Document 2 describes a ceramic composite containing 50% by weight to 99% by weight of sodium ferrite and 1% by weight to 50% by weight of an inorganic binder, and having a specific surface area of ​​1 m ２ / g to 50m ２ / g. As the inorganic binder, an inorganic material containing one or more of Na, Li, K, Ca, Mg, Si, Al, Ca, Fe, and Zn is disclosed, and specifically, silicates such as sodium silicate and lithium silicate; and metal phosphates such as aluminum phosphate and magnesium phosphate are disclosed. Because the inorganic binder has excellent moldability, it is possible to form a molded product containing a high concentration of sodium ferrite, and the carbon dioxide fixation and recovery capacity can be improved.

[0006] Furthermore, Patent Document 2 discloses a method for producing a solid recovered material, in which sodium ferrite powder and an inorganic binder are kneaded together, extruded, and fired.

[0007] International Publication No. WO 2022 / 030338 International Publication No. WO 2022 / 259929

[0008] In Patent Document 1, the absorption rate is increased by increasing the specific surface area, but there is a demand for further increasing the amount of carbon dioxide recovered per mass of the solid recovery material. On the other hand, the strength of the solid recovery material decreases as the specific surface area is increased to increase the amount of carbon dioxide recovered, and as a result, the structure becomes more susceptible to collapse due to pressure during use. Thus, there is a trade-off between the amount of carbon dioxide recovered and the strength.

[0009] An object of the present invention is to provide a solid carbon dioxide capture material that has both an excellent carbon dioxide capture capacity and strength, and a method for producing the same.

[0010] In order to solve the above problems, this document discloses the following inventions. [1] A solid carbon dioxide capture material containing sodium, iron, and aggregate, and having pores with a diameter of 0.05 μm or more in a cross section. [2] The solid carbon dioxide capture material according to [1] above, having a porosity of 10 to 70% as measured by mercury intrusion porosimetry. [3] A solid carbon dioxide capture material containing pores with a diameter of 0.1 mm or more in a cross section. ２[4] The carbon dioxide solid capture material according to any one of [1] to [3] above, which has 10 to 400 holes per cross section. [5] The carbon dioxide solid capture material according to any one of [1] to [4] above, which has an average diameter of 50 holes in a cross section of 0.05 to 50 μm. [6] The carbon dioxide solid capture material according to any one of [1] to [4] above, which is cylindrical and has a diameter of 0.5 to 5 mm and a height of 1 to 15 mm. [7] The carbon dioxide solid capture material according to any one of [1] to [4] above, which has an average crushing strength of 20 kgf / mm ２ The solid carbon dioxide capture material according to any one of [1] to [5] above. [7] A method for producing a solid carbon dioxide capture material, comprising: (a) a step of kneading a sodium raw material, an iron raw material, an aggregate, and a pore-forming agent, wherein the mass ratio of aggregate / sodium raw material and iron raw material is 1 / 19 to 4, and the mass ratio of pore-forming agent / (sodium raw material, iron raw material, and aggregate) is 1 / 1000 to 3 / 10, (b) a step of molding the kneaded mixture obtained in the step (a), and (c) a step of firing the molded product obtained in the step (b). [8] A method for producing a solid carbon dioxide capture material according to [7] above, comprising thermally decomposing the pore-forming agent with the heat from the firing in the step (c).

[0011] The solid carbon dioxide capture material of the present invention can achieve both an excellent carbon dioxide capture rate and strength.

[0012] Scanning electron microscope photograph (350x magnification) of a cross section of the solid recovery material obtained in Example 2. Scanning electron microscope photograph (350x magnification) of a cross section of the solid recovery material obtained in Comparative Example 1.

[0013] <Carbon dioxide capture material> Hereinafter, embodiments for carrying out the present invention will be described. The following description of preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its application method, or its uses.

[0014] A solid carbon dioxide capture material (sometimes simply referred to as a "solid capture material") according to one embodiment of the present invention will be described.

[0015] The solid recovery material according to this embodiment contains sodium (Na), iron (Fe) and aggregate, and has pores with a diameter of 0.05 μm or more in cross section.

[0016] The composition ratio of sodium (Na) contained in the solid recovery material according to this embodiment is preferably 1 to 30 mass %. The composition ratio of Na is more preferably 3 to 25 mass %, and even more preferably 5 to 20 mass %. If the composition ratio is within this range, a good carbon dioxide recovery rate will be achieved.

[0017] The form of Na contained in the solid recovery material according to this embodiment is not particularly limited, and may contain one type or two or more types. For example, Na ２ CO ３ (H ２ O) and Na ２ CO ３ Examples include:

[0018] The iron (Fe) content of the solid recovered material is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and even more preferably 20 to 40% by mass. When the iron content is within this range, the strength is excellent.

[0019] The form of Fe contained in the solid recovery material is not particularly limited. In other words, Fe may be a simple substance or a compound, and its phase (α, β, γ, etc.) is not limited. In addition, in the case of a compound, components other than Fe are not limited. Furthermore, the solid recovery material may contain Fe in one or more forms. For example, Fe may be in the form of α-Fe, FeO, Fe ３ O ４ Examples include:

[0020] The Fe and Na contained in the solid recovered material are converted into sodium ferrite (NaFeO ２ In other words, the solid recovery material may contain sodium ferrite. The form of sodium ferrite is not particularly limited, and one or more types may be included. For example, the form of sodium ferrite may be α-NaFeO ２ and β-NaFeO ２ Examples include:

[0021] The solid recovery material according to this embodiment is 18 to 95 mass % sodium ferrite (NaFeO ２) and 5 to 82 mass% of aggregate. ２ ) and 15 to 81 mass % of aggregate, and more preferably contains 20 to 80 mass % of sodium ferrite (NaFeO ２ It is more preferable that the total content of sodium ferrite and aggregate is 100% by mass. If the total content is within the above range, the desired carbon dioxide recovery rate and strength can be obtained.

[0022] Sodium ferrite can react with carbon dioxide, and the reaction is NaFeO when the gas does not contain water vapor. ２ +1 / 2CO ２ →1 / 2Na ２ CO ３ +1 / 2Fe ２ O ３ , when water vapor is included, NaFeO ２ +CO ２ +1 / 2H ２ O → NaHCO ３ +1 / 2Fe ２ O ３ Therefore, the term "containing sodium ferrite" also includes the state after such a reaction.

[0023] Furthermore, by placing the solid recovery material after reacting with carbon dioxide under a predetermined temperature condition, the carbon dioxide can be desorbed. In this way, the solid recovery material can repeatedly adsorb, fix, and desorb carbon dioxide.

[0024] The aspect ratio of the average major axis diameter to the average minor axis diameter of the primary particles of sodium ferrite in the present invention (average major axis diameter / average minor axis diameter) is preferably 1 to 2. When the aspect ratio is 2 or less, the primary particles of sodium ferrite are less likely to aggregate with each other and can have high dispersibility. The aspect ratio of the primary particles of sodium ferrite is more preferably 1.1 to 1.9.

[0025] The aggregate in the present invention may be either an inorganic material or an organic material. The aggregate serves to maintain the shape of the solid recovered material by undergoing processes such as mixing with the sodium raw material, the iron raw material, and the pore-forming agent, molding, and applying thermal energy, and also includes materials that act as binders.

[0026] For example, the inorganic material may include a material containing one or more of Na, Li, K, Ca, Mg, Si, Al, Ca, Fe, Sn, Ti, Zr, and Zn. Specific examples of the inorganic material include silicates, metal phosphates, metal alcoholates, organopolysiloxanes, organic-inorganic composite polymers, alumina sol, synthetic mica, phosphonitrile chloride, and cement.

[0027] Examples of silicates include water-soluble silicates such as sodium silicate, potassium silicate, lithium silicate, and ammonium silicate, as well as colloidal silica and organic metal siliconates. Examples of metal phosphates include aluminum phosphate, magnesium phosphate, calcium phosphate, iron phosphate, and zinc phosphate. Examples of metal alcoholates include alcoholates of silicon, aluminum, tin, titanium, and zirconium. Examples of organopolysiloxanes include silicone and alkyl silicates such as ethyl silicate, butyl silicate, phenyl silicate, octyl silicate, and lauryl silicate. Examples of organic-inorganic composite polymers include mixtures such as emulsion mixtures and aqueous resin mixtures, and graft compounds such as organic polymer grafts to glass or minerals. Examples of alumina sols include feathery particles and granular particles. Examples of synthetic mica include KMg ３ AlSi ３ O １０ F ２ It is a silicate mineral represented by the formula: K is Na, Ca, Sr, Ba, and part of Mg is Al, Fe ２＋Examples include those in which Al is substituted with Zn, Be, B, Co, Mn, Li, or Zn, and Si is substituted with Zn, Be, B, Co, or Fe. Phosphonyl chloride includes various compounds as polyphosphazene derivatives. Examples of cement include polytranth cement and alumina cement.

[0028] The organic material in the present invention may be, for example, a polymer material selected from polystyrene, polyethylene, polypropylene, nitrile butadiene, silicone, fluororesin, and cellulose. The weight-average molecular weight of the organic material is preferably 1,000 to 100,000.

[0029] The solid recovery material according to the present invention has pores therein. Specifically, the pores have a diameter of 0.05 μm or more in the cross section. The pore diameter is the diameter of the smallest circle that can contain the entire pore in an image obtained by cutting the solid recovery material along its short axis and observing the cross section with a scanning electron microscope. The inclusion of such pores allows the gas to be treated to reach the interior of the solid recovery material, resulting in a large carbon dioxide recovery rate relative to the mass of the solid recovery material.

[0030] Furthermore, the solid recovery material preferably has pores on its outer surface as well as inside. The solid recovery material preferably has a porosity of 10 to 70%. The porosity is measured by mercury intrusion porosimetry in accordance with JIS R1655:2003. A porosity of 10% or more allows for a large amount of carbon dioxide recovery, while a porosity of 70% or less allows for good strength. The porosity is more preferably 20% to 65%. The porosity is even more preferably 25% to 60%.

[0031] The solid recovery material has a cross section of 0.1 mm ２ It is preferable that the porous carbon dioxide contains 10 to 400 pores per pore, more preferably 20 to 350 pores, and even more preferably 30 to 300 pores. When the number of pores is 10 or more, a large amount of carbon dioxide can be recovered, and when the number of pores is 400 or less, good strength can be obtained. As described above, the "pores" here have a diameter of 0.05 μm or more.

[0032] The solid recovery material has pores with a diameter of 0.05 μm or more in its cross section. The upper limit of the pore size is not particularly limited, but in order to ensure the strength of the solid recovery material, it is preferably less than 500 μm, more preferably 300 μm or less, and even more preferably 100 μm or less.

[0033] The average diameter of the pores in the cross section of the solid recovery material (pore size) is preferably 0.05 to 50 μm, more preferably 1 to 30 μm, and even more preferably 2 to 20 μm. This average value is obtained by measuring the diameters of 50 pores in the cross section that have a diameter of 0.05 μm or more as described above and calculating the average value.

[0034] The shape of the holes in the cross section of the solid recovery material may be circular, elliptical, polygonal, or irregular, and is not particularly limited, but is preferably circular. The aspect ratio of the holes in the cross section of the solid recovery material is preferably 1 / 3 to 3.

[0035] The shape of the solid recovery material is not particularly limited, but it is preferably formed into a cylindrical shape.

[0036] When the solid recovery material is cylindrical, it preferably has a diameter of 0.5 to 5 mm and a height of 1 to 15 mm. A diameter of 0.5 mm or more and a height of 1 mm or more allows for the formation of gaps between the solid recovery material packed in the adsorption tower through which gas can pass. As a result, pressure loss can be kept low. Furthermore, a diameter of 5 mm or less and a height of 15 mm or less allows for a large area of ​​the solid recovery material packed in the adsorption tower. As a result, the opportunities for gas to come into contact with the solid recovery material are increased, enabling efficient recovery of carbon dioxide.

[0037] The bulk density of the solid recovered material is 0.4 to 1.2 g / cm ３ It is preferable that the bulk density is within the above range. If the bulk density is within the above range, the solid recovery material has excellent packing properties in a column. The bulk density may also be referred to as apparent density, and is measured in accordance with JIS Z2504:2020. Specifically, the bulk density is a value obtained by pouring the solid recovery material into a container having a known volume using a funnel, and dividing the mass of the solid recovery material that has entered the container by the volume of the container.

[0038] The average crushing strength of the solid recovered material is 20 kgf / mm ２ It is preferable that the average crushing strength is 20 kgf / mm or more. ２ If the average crushing strength is less than 200 kgf / mm, the solid recovered material may collapse due to the impact during filling or the pressure during use. ２ The crushing strength is a value measured in accordance with JIS Z 8841-1993, as follows: The solid recovered material is placed in the center of the fixed compression surface, and a load is applied to the solid recovered material by moving the movable pressure surface at a constant speed. The crushing strength is the maximum value of the load that can be applied until the solid recovered material is completely destroyed.

[0039] Furthermore, the amount of carbon dioxide recovered per unit mass of the solid recovery material, i.e., the recovery rate, is preferably 6.5% by mass or more. However, the amount of carbon dioxide recovered also depends on the elemental content of sodium and iron in the solid recovery material. The ratio of the carbon dioxide recovery rate (mass%) to the total elemental content (mass%) of Na and Fe in the solid recovery material is preferably 13% or more or 15% or more. The amount of carbon dioxide recovered is measured by allowing the solid recovery material to fully adsorb carbon dioxide, then desorbing the carbon dioxide by heating, and measuring the amount of desorbed carbon dioxide with an infrared gas monitor. Based on the results, the recovery rate (mass%) is calculated as the amount of carbon dioxide recovered per unit mass of the solid recovery material used. The carbon dioxide adsorption conditions are 40°C, relative humidity 80% RH, and a GHSV of 490h using a mixed gas of 10 vol% carbon dioxide and 90 vol% nitrogen. －１ The heating temperature during desorption is, for example, 150° C., as long as desorption of carbon dioxide can be observed.

[0040] <Manufacturing Method> The manufacturing method of the solid recovered material includes: (a) a step of kneading a sodium raw material, an iron raw material, an aggregate, and a pore-forming agent; (b) a step of shaping the kneaded mixture obtained in step (a); and (c) a step of firing the shaped product obtained in step (b).

[0041] In step (a), examples of the sodium source include sodium hydroxide, sodium carbonate, sodium carbonate hydrate, and sodium nitrite.

[0042] In step (a), examples of the iron raw material include magnetite, maghemite, goethite, and hematite.

[0043] In step (a), the iron source and / or the sodium source may be a compound containing sodium and iron, such as sodium ferrite. The sodium ferrite may be obtained by a conventional method.

[0044] In step (a), the mass ratio of aggregate to the total of the sodium raw material and the iron raw material is 1 / 19 to 4, and the mass ratio of pore-forming agent to (sodium raw material, iron raw material, and aggregate) is 1 / 1000 to 3 / 10. A solvent may be added during kneading. The solvent is not particularly limited, but water is an example.

[0045] A pore-forming agent is a substance that can be dispersed in a kneaded or molded product while maintaining its shape (i.e., being solid), but can be removed from the molded product by dissolving, melting, or decomposing to form pores.

[0046] The pore-forming agent is not particularly limited, but is preferably in particulate form.

[0047] The shape of the pore-forming agent is not particularly limited, but a spherical shape is preferred.

[0048] As the pore-forming agent, it is preferable to use at least one of a pore-forming material and a foaming agent, and two or more of them may be used.

[0049] The pore-forming material is preferably removed by thermal decomposition during firing of the solid recovery material, but may also be removed by dissolving in a solvent. The dimensions of the pore-forming material need only be equivalent to the dimensions of the desired pores. The pore-forming material may be polydisperse (having a wide particle size distribution) or monodisperse (having a narrow particle size distribution). Examples of pore-forming materials include polymers such as polystyrene, acrylic, and methacrylic.

[0050] The foaming agent is a compound that generates gas by thermal decomposition. It is preferable that the foaming agent decomposes due to the heat generated during firing. The foaming agent may be either organic or inorganic, and is preferably organic. Examples of organic foaming agents include amide-based organic compounds, imine-based organic compounds, and sulfone-based organic compounds. Examples of inorganic foaming agents include sodium bicarbonate.

[0051] The kneading method in step (a) is not particularly limited as long as it can uniformly knead the materials, and examples thereof include a ball mill, a stirrer, a kneader, and the like.

[0052] The method for step (b) is not particularly limited as long as it can mold the obtained kneaded product into a desired shape, and can include injection molding, extrusion molding, etc. In extrusion molding, the kneaded product is extruded from a die and cut to obtain a molded product of desired dimensions, and in particular, a cylindrical molded product can be obtained by using a circular die.

[0053] In step (c), the molded product can be hardened by firing. The firing temperature and time are set so as to obtain a solid recycled material having the desired strength. Although it depends on the type of aggregate, it is preferable to perform the treatment at a temperature of 100°C or higher and 1000°C or lower.

[0054] In the firing step (c), the pore-forming agent is preferably removed by thermal decomposition and / or gasification. When the pore-forming agent is removed by thermal decomposition and / or gasification, pores can be formed in the resulting fired product by the firing step (c).

[0055] <Use of solid recovery material> Solid recovery material can be used to recover carbon dioxide. Granular solid recovery material is packed into a column to form an adsorption tower, and carbon dioxide-containing gas is passed through the adsorption tower.

[0056] The solid recovery material that has adsorbed carbon dioxide through contact with the gas can then be heated to desorb the carbon dioxide. After desorption, the solid recovery material can be used for further adsorption and fixation of carbon dioxide, allowing for repeated use.

[0057] In this specification, mass, parts by mass, and mass % are used synonymously with weight, parts by weight, and % by weight, respectively.

[0058] <Preparation of Solid Recovery Material> [Example 1] 100 parts by mass of α-sodium ferrite and 100 parts by mass of cordierite (manufactured by Resonac) were weighed and mixed. Next, 2 parts by mass of a pore-forming material was added and mixed. The obtained mixed powder and 48 parts by mass of water were added to a double-arm kneader and kneaded for 1 hour. Thereafter, the mixture was molded into a diameter of 3 mm using an extruder and cut to a length of 7 mm, thereby obtaining cylindrical pellets. The pellets were fired in a firing furnace at 500°C for 3 hours.

[0059] [Examples 2 to 11] Solid recovery materials of Examples 2 to 11 were obtained in the same manner as in Example 1, except that the conditions were changed as shown in Table 1.

[0060] A scanning electron microscope photograph of the cross section of the solid recovered material obtained in Example 2 is shown in FIG.

[0061] Pores with diameters of 0.05 μm or more were observed in the cross section of the solid recovery material obtained in Example 2. The aspect ratio of each pore was 3 or less, and the average aspect ratio of 50 pores was 9 / 10.

[0062] Comparative Example 1: 100 parts by mass of α-sodium ferrite and 100 parts by mass of cordierite were weighed and mixed. The resulting mixed powder and 50 parts by mass of water were added to a double-arm kneader and kneaded for 1 hour. The mixture was then molded into a diameter of 3 mm using an extruder and cut into a length of 7 mm to obtain cylindrical pellets. After cutting, the pellets were fired in a firing furnace at 500°C for 3 hours.

[0063] The carbon dioxide recovery amount of the solid carbon dioxide recovery material obtained in Comparative Example 1 was 4 mass% relative to the solid carbon dioxide recovery material. The carbon dioxide recovery temperature was measured under the same conditions using a thermogravimetric analyzer as in Example 1. The recovery (desorption) temperature of the carbon dioxide absorbed in the sample was measured and found to be 102°C.

[0064] [Comparative Examples 2 to 4] Solid carbon dioxide capture materials of Comparative Examples 2 to 4 were obtained in the same manner as in Comparative Example 1, except that the materials for the solid carbon dioxide capture material (sodium raw material, iron raw material, aggregate, pore-forming agent, and water) and the cut length of the solid carbon dioxide capture material were variously changed as shown in Table 1.

[0065] The compositions of the solid recovery materials obtained in the Examples and Comparative Examples are shown in Table 2, their physical properties in Table 3, and their performance in Table 4.

[0066] A scanning electron microscope photograph of the cross section of the solid recovered material obtained in Comparative Example 1 is shown in FIG.

[0067] The carbon dioxide solid recovery material obtained in the comparative example used a porous material as the aggregate, but no pores having a diameter of 0.05 μm or more were found inside it.

[0068] On the other hand, the carbon dioxide solid capture material according to the present invention has pores with a diameter of 0.05 μm or more inside, i.e., on the cross section, of the solid capture material, and has good carbon dioxide fixation and capture performance. This is thought to be because carbon dioxide gas permeates not only the surface but also the inside of the carbon dioxide solid capture material, resulting in high capture capacity.

[0069] Furthermore, the solid carbon dioxide capture material according to the present invention has sufficient strength despite having internal pores, and therefore can be used by packing it into a column or the like.

[0070] <Evaluation> [Size measurement] The major and minor axes of 50 particles were measured using a vernier caliper. The average major and minor diameters were calculated from the average of the measured values. The major and minor diameters of each example were consistent with the size at the time of molding. In other words, the average major diameter was consistent with the cut length shown in Table 1, and the average minor diameter was 3 mm. Table-based results are omitted.

[0071] [Composition] The solid recovered material was crushed in a mortar and further pelletized, and the α-sodium ferrite and aggregate were identified from the peaks obtained using a fully automatic multipurpose X-ray diffractometer D8 ADVANCE manufactured by BRUKER, and their contents were measured.

[0072] The solid recovered material was crushed in a mortar and further pelletized, and elemental analysis was performed using a Rigaku ZSX Primus II scanning X-ray fluorescence analyzer to quantify the elemental contents (mass%) of Na and Fe.

[0073] [Strength] Using an Imada digital force gauge ZP-500N, pressure was applied from the side in the minor axis direction (radial direction) to the center of the solid recovered material, and the strength (kgf / mm ２ The average value of the crushing strengths of the 50 grains was determined as the average crushing strength.

[0074] [Bulk Density] The bulk density of the solid recovered material was measured in accordance with JIS Z2504:2020.

[0075] [Observation of Internal Holes in Solid Recovery Material] The solid recovery material was cut near the center along the short axis direction (radial direction) using a high-speed cutting machine (manufactured by HIKOKI). The cross section was observed with a Hitachi High-Technologies S-4800 scanning electron microscope to confirm the presence or absence of holes with a diameter of 0.05 μm or more. When holes with a diameter of 0.05 μm or more were found, the hole diameter and number of holes were measured in the cross section where the presence or absence of holes was confirmed as follows.

[0076] The diameter of the smallest circle that encompassed the entire hole was measured for each hole, and the average of the values ​​obtained for 50 holes was taken as the hole diameter of the solid recovery material.

[0077] 0.1 mm of the cross section ２ The number of holes present per 0.1 mm ２ The number of holes per hole was calculated.

[0078] [Porosity] The porosity of the solid carbon dioxide capture material was measured by mercury intrusion porosimetry in accordance with JIS R1655:2003.

[0079] [Carbon dioxide recovery rate] A packed column (diameter 25 mm × height 500 mm) was used as an adsorption tower, and a solid recovery material was loaded to a height of 300 mm. The temperature inside the system was adjusted to 40°C and the relative humidity to 80 RH%, and a mixed gas of 10 vol% carbon dioxide and 90 vol% nitrogen was passed through the column at GHSV 490 h. －１The mixture was aerated for 7 hours at 150°C. The temperature inside the packed tower column was then raised to 150°C, and carbon dioxide was desorbed from the solid recovery material over a period of 2 hours. The instantaneous concentration of the desorbed carbon dioxide was measured using an infrared gas monitor RI-557 (manufactured by Riken Keiki Co., Ltd.), and the amount of carbon dioxide recovered was calculated based on the measurement results. Furthermore, the carbon dioxide recovery rate (mass%) was calculated as the amount of carbon dioxide recovered per unit mass of the solid recovery material at the time of packing.

[0080] [Carbon dioxide recovery temperature] 1 g of sample was placed on a combustion boat (12 × 60 × 9 mm) and a model combustion flue gas was passed through at 500 mL / min for 3 hours. The model combustion flue gas was composed of 80 vol% nitrogen and 20 vol% carbon dioxide, and its relative humidity (RH) was 80%. The model combustion flue gas was obtained by bubbling a mixture of 400 mL / min nitrogen and 100 mL / min carbon dioxide into water at room temperature (25°C).

[0081] For the sample after aeration, a DTG (differential thermogravimetry) curve was obtained using a NETZSCH STA449F3 Jupiter. In detail, 10 mg of the weighed sample was loaded into a sample holder attached to the device, and TG (thermogravimetry) was performed by raising the temperature to 200 ° C. at 2 ° C. / min while aerating dry air through the sample holder at 300 mL / min. The DTG curve is a differential curve of the TG curve. The temperature at which the DTG curve takes the maximum value (also the local maximum value) was considered to be the carbon dioxide recovery temperature. Note that this measurement method observes the carbon dioxide desorption process, but since the desorption temperature and the recovery temperature are the same, the measured temperature can be considered to be the carbon dioxide recovery temperature.

[0082]

[0083]

[0084]

[0085]

[0086] As shown in the results in each table, the use of the pore-forming agent resulted in the formation of pores inside the solid recovery material. As a result, a large amount of carbon dioxide was fixed in the solid recovery material, and good crushing strength was obtained.

[0087] Note that Example 6 has a lower content of sodium ferrite, and therefore recovers less carbon dioxide than the above-mentioned Comparative Examples 1 to 3. However, when Example 6 and Comparative Example 4, which have the same content of sodium ferrite in the solid recovery material, are compared, Example 6 fixes more carbon dioxide than Comparative Example 4. In other words, it was confirmed that the presence of pores inside the solid recovery material increases the amount of carbon dioxide recovered.

Claims

1. A solid carbon dioxide capture material comprising sodium, iron, and aggregate, and having pores in cross section with a diameter of 0.05 μm or more.

2. The solid carbon dioxide recovery material according to claim 1, having a porosity of 10 to 70% as measured by mercury intrusion porosimetry.

3. 0.1 mm in cross section ２ The solid carbon dioxide capture material according to claim 1, comprising 10 to 400 of the pores per pore.

4. The solid carbon dioxide capture material according to claim 1, wherein the average diameter of 50 of the pores in the cross section is 0.05 to 50 μm.

5. The solid carbon dioxide recovery material according to claim 1, which is cylindrical and has a diameter of 0.5 to 5 mm and a height of 1 to 15 mm.

6. Average crushing strength is 20 kgf / mm ２ The solid carbon dioxide capture material according to claim 1 .

7. A method for producing a solid carbon dioxide recovery material, comprising: (a) a step of kneading a sodium raw material, an iron raw material, an aggregate, and a pore-forming agent, wherein the mass ratio of aggregate / sodium raw material and iron raw material is 1 / 19 to 4, and the mass ratio of pore-forming agent / (sodium raw material, iron raw material, and aggregate) is 1 / 1000 to 3 / 10; (b) a step of molding the kneaded product obtained in the step (a); and (c) a step of firing the molded product obtained in the step (b).

8. The method for producing a solid carbon dioxide capture material according to claim 7, comprising thermally decomposing the pore-forming agent with the heat from the firing in step (c).

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