JP2018051504A - Adsorbent, adsorbent body containing adsorbent, method for producing the same, and carbon dioxide removing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an adsorbent that can improve the adsorption of carbon dioxide while using a binder.SOLUTION: The present invention provides a method for producing an adsorbent used for removing carbon dioxide from a treatment gas containing the carbon dioxide, the method including the step of sintering a mixture containing a cerium compound (excluding a cerium oxide) and a binder to obtain an adsorbent containing a cerium oxide.SELECTED DRAWING: None

Description

  The present invention relates to an adsorbent, an adsorbent comprising the adsorbent, a production method thereof, and a carbon dioxide removal method.

In recent years, global warming due to greenhouse gas emissions has become a global problem. Examples of the greenhouse gas include carbon dioxide (CO ₂ ), methane (CH ₄ ), and chlorofluorocarbons (CFCs and the like). Among the greenhouse gases, carbon dioxide has the greatest influence, and construction of a method for removing carbon dioxide (for example, carbon dioxide discharged from thermal power plants, steelworks, etc.) is required.

Carbon dioxide is known to affect the human body. For example, when a gas containing carbon dioxide at a high concentration is sucked, drowsiness, health damage and the like are caused. In spaces with high human density (buildings, vehicles, etc.), the concentration of carbon dioxide in the room (hereinafter referred to as “CO ₂ concentration” in some cases) is likely to increase due to human expiration, and the CO ₂ concentration is adjusted by ventilation. There is a case.

In order to quickly ventilate indoor air and outside air, it is necessary to operate a blower such as a blower. Moreover, since the temperature and humidity of the air taken in from the outside (outside air) are not adjusted, it is necessary to operate the cooling in the summer and to operate the heating in the winter. For these reasons, an increase in indoor CO ₂ concentration is a factor in increasing power consumption associated with air conditioning.

The amount of reduction of carbon dioxide in the room due to ventilation (CO ₂ reduction amount) is expressed by the following equation. In the following equation, the CO ₂ concentration can be kept constant if the amount of CO ₂ decrease on the left side is equivalent to the amount of CO ₂ increase due to human expiration.
CO ₂ reduction amount = (CO ₂ concentration in the chamber - external air CO ₂ concentration) × ventilation

However, in recent years, since the CO ₂ concentration in the outside air has increased, the difference in CO ₂ concentration from the room has become smaller. For this reason, the amount of ventilation required to adjust the CO ₂ concentration is also increasing. In the future, when the CO ₂ concentration in the outside air further increases, it is considered that the power consumption increases by adjusting the CO ₂ concentration by ventilation.

  The said subject arises by ventilation with external air. Therefore, if carbon dioxide can be selectively removed using a method other than ventilation, the amount of ventilation can be reduced, and as a result, power consumption associated with air conditioning may be reduced.

  Also, in spaces (air stations, submersibles, etc.) shielded from the outside air in which air exists, it is difficult to ventilate the outside air and room air, so it is necessary to selectively remove carbon dioxide by methods other than ventilation. There is.

Examples of a solution to the problem include a method of removing carbon dioxide by a chemical absorption method, a physical absorption method, a membrane separation method, an adsorption separation method, a cryogenic separation method, or the like. For example, a method of separating and recovering carbon dioxide using a CO ₂ adsorbent (hereinafter simply referred to as “adsorbent”) (CO ₂ separation and recovery method) can be mentioned. For example, zeolite is known as an adsorbent (see, for example, Patent Document 1 below).

JP 2000-140549 A

  By the way, when removing carbon dioxide from the gas to be treated using an adsorbent, an adsorbent including a base material to which the adsorbent is attached may be used. In this case, from the viewpoint of easily adsorbing the adsorbent to the substrate, the adsorbent may be adhered to the substrate using a binder. And, for the carbon dioxide removal method using an adsorbent, from the viewpoint of improving the carbon dioxide removal efficiency, it is required to improve the amount of carbon dioxide adsorbed to the adsorbent, while using a binder. There is a need to improve the amount of carbon dioxide adsorbed.

  This invention is made | formed in view of the said situation, and it aims at providing the adsorption agent which can improve the adsorption amount of a carbon dioxide, and its manufacturing method, using a binder. Moreover, an object of this invention is to provide an adsorbent provided with the said adsorbent, and its manufacturing method. Furthermore, an object of the present invention is to provide a carbon dioxide removal method using the adsorbent.

  The method for producing an adsorbent according to the present invention is a method for producing an adsorbent used for removing carbon dioxide from a gas to be treated containing carbon dioxide, comprising a cerium compound (excluding cerium oxide) and a binder. And firing the mixture to obtain an adsorbent containing cerium oxide.

  The adsorbent according to the present invention is an adsorbent used for removing carbon dioxide from a gas to be treated containing carbon dioxide, and is a baked product of a mixture containing a cerium compound (excluding cerium oxide) and a binder. Yes, containing cerium oxide.

According to the adsorbent and the manufacturing method thereof according to the present invention, the amount of carbon dioxide adsorbed on the adsorbent can be improved while using the binder. According to the adsorbent and the method for producing the same according to the present invention, it is possible to obtain excellent CO ₂ adsorbability (carbon dioxide adsorbability, carbon dioxide scavenging ability) while using a binder.

By the way, in the method using a conventional adsorbent such as zeolite, when the CO ₂ concentration of the gas to be treated is low, the carbon dioxide removal efficiency tends to decrease. On the other hand, according to the adsorbent and the manufacturing method thereof according to the present invention, the amount of carbon dioxide adsorbed on the adsorbent can be improved when the CO ₂ concentration of the gas to be treated is low. In this case, carbon dioxide can be efficiently removed when the CO ₂ concentration of the gas to be treated is low.

  In the adsorbent and the production method thereof according to the present invention, the cerium compound contains at least one selected from the group consisting of cerium carbonate, cerium hydrogencarbonate, cerium oxalate, and cerium hydroxide. Also good.

  In the method for producing an adsorbent according to the present invention, the binder may contain silica. The adsorbent according to the present invention may further contain silica.

  The method for producing an adsorbent according to the present invention may be an embodiment in which the mixture is baked at 150 ° C. or higher, or an embodiment in which the mixture is baked at 250 ° C. or higher.

  The method for producing an adsorbent according to the present invention is a method for producing an adsorbent comprising a base material and an adsorbent attached to the base material, the step of bringing the base material into contact with the mixture, and Baking the mixture by the adsorbent manufacturing method to obtain the adsorbent. The adsorbent according to the present invention includes a base material and the adsorbent described above, and the adsorbent adheres to the base material. According to the adsorbent and the method for producing the same according to the present invention, it is possible to improve the amount of carbon dioxide adsorbed to the adsorbent while using the binder, and to improve the carbon dioxide removal efficiency.

  The carbon dioxide removal method according to the present invention includes the adsorbent obtained by the adsorbent production method described above, the adsorbent obtained by the adsorbent production method described above, the adsorbent described above, or the above-described adsorbent. A step of bringing the adsorbent of the adsorbent into contact with a gas to be treated containing carbon dioxide to adsorb carbon dioxide to the adsorbent; According to the carbon dioxide removal method of the present invention, the amount of carbon dioxide adsorbed on the adsorbent can be improved, and the carbon dioxide removal efficiency can be improved.

ADVANTAGE OF THE INVENTION According to this invention, the adsorption amount of the carbon dioxide with respect to adsorption agent can be improved, using a binder. In particular, according to the present invention, when the CO ₂ concentration of the gas to be processed is low, the amount of carbon dioxide adsorbed on the adsorbent can be improved.

FIG. 1 is a schematic diagram showing an air conditioner according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an air conditioning system according to an embodiment of the present invention.

  In this specification, the numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present specification, the upper limit value or lower limit value of a numerical range of a certain step may be replaced with the upper limit value or lower limit value of the numerical range of another step. Further, in the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

  In this specification, the term “process” is not limited to an independent process, and is included in this term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. It is. The materials exemplified in the present specification can be used singly or in combination of two or more unless otherwise specified. In the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. Means. In this specification, content of a binder means content of the solid content of a binder.

  Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

<Adsorbent and production method thereof>
The adsorbent (carbon dioxide scavenger) and the method for producing the same according to the present embodiment are used for removing (for example, collecting) carbon dioxide from a gas to be treated (gas to be treated) containing carbon dioxide. It is an agent and its manufacturing method. The adsorbent according to the present embodiment is a fired product of a raw material mixture containing a cerium compound (excluding cerium oxide) and a binder, and contains cerium oxide. The method for producing an adsorbent according to the present embodiment includes a firing step of firing a raw material mixture containing a cerium compound (excluding cerium oxide; the same applies hereinafter) and a binder to obtain an adsorbent containing cerium oxide. . The raw material mixture may be a liquid containing a cerium compound, a binder, and water.

According to the adsorbent and the manufacturing method thereof according to the present embodiment, the amount of carbon dioxide adsorbed can be improved while using a binder. The reason why such excellent CO ₂ adsorptivity is obtained is not clear, but the present inventor presumes that it is as follows. That is, if the adsorbent attached to the substrate has pores capable of adsorbing carbon dioxide, it is easy to obtain an excellent CO ₂ adsorption amount. Here, when a raw material mixture containing cerium oxide and a binder (for example, a dispersion containing cerium oxide and a binder) is brought into contact with the substrate, pores previously formed in the cerium oxide are blocked by the binder. As a result, the residual amount of pores capable of adsorbing carbon dioxide decreases, and the adsorption amount is low. On the other hand, when the raw material mixture containing the cerium compound (excluding cerium oxide) and the binder (for example, a dispersion containing the cerium compound and the binder) is brought into contact with the substrate and then the raw material mixture is fired, When the cerium compound is physically adsorbed and calcined, and cerium oxide is formed, it is assumed that pores capable of adsorbing carbon dioxide are formed at positions where no binder is attached to the cerium oxide. . In this case, the pores are not blocked by the binder, a sufficient amount of pores capable of adsorbing carbon dioxide is obtained, and an excellent CO ₂ adsorption amount is obtained.

According to the present embodiment, excellent CO ₂ adsorption is obtained particularly when the CO ₂ concentration of the gas to be processed is low. Further, according to the present embodiment, the cerium compound is fired at the time of use to obtain a cerium oxide, so that the deterioration of the cerium oxide can be easily suppressed as compared with the case where the cerium oxide is stored for a long period of time.

Examples of the cerium oxide in the adsorbent include CeOx (x = 1.5 to 2.0), and specific examples include CeO ₂ and Ce ₂ O ₃ . The content of cerium oxide in the adsorbent may be, for example, 50 to 99% by mass based on the total mass of the adsorbent. The greater the content of cerium oxide, the more the carbon dioxide adsorption can be improved. The content of cerium oxide can be adjusted by, for example, the content of the cerium compound in the raw material mixture for obtaining the adsorbent.

  The adsorbent according to this embodiment may further contain an oxide other than cerium oxide. The oxide other than cerium oxide is, for example, an oxide derived from a binder. Examples of oxides other than cerium oxide include silica, alumina, zirconia, and the like. From the viewpoint of further improving the amount of carbon dioxide adsorbed, silica can be used. The content of oxides (silica and the like) other than cerium oxide in the adsorbent may be, for example, 1 to 50% by mass based on the total mass of the adsorbent.

  The adsorbent (adsorbent containing cerium oxide) according to this embodiment can be obtained by firing a raw material mixture containing a cerium compound and a binder. By firing the raw material mixture containing the cerium compound, the cerium compound is decomposed and cerium is oxidized to obtain a cerium oxide.

  The cerium compound is, for example, solid. As the cerium compound, a cerium compound capable of obtaining a cerium oxide by firing can be used. As the cerium compound, at least one selected from the group consisting of cerium carbonate, cerium bicarbonate, cerium oxalate, and cerium hydroxide is used from the viewpoint of further improving the amount of carbon dioxide adsorbed. Can do. The cerium compound can be produced by a known method. Moreover, you may use the compound marketed as a cerium compound.

  The cerium compound may be, for example, a compound containing cerium ions and at least one ion selected from the group consisting of carbonate ions and hydrogen carbonate ions. The cerium carbonate is a compound containing, for example, cerium ions and carbonate ions. Cerium hydrogen carbonate is a compound containing, for example, cerium ions and hydrogen carbonate ions.

  Examples of the cerium carbonate include cerium carbonate and cerium oxycarbonate. Examples of cerium bicarbonate include cerium bicarbonate. The cerium compound may be at least one selected from the group consisting of cerium carbonate, cerium bicarbonate, and cerium oxycarbonate from the viewpoint of further improving the amount of carbon dioxide adsorbed.

  Examples of cerium oxalate include cerium oxalate and cerium oxalate hydrate. Examples of cerium oxalate hydrate include cerium oxalate nonahydrate.

  The content of the cerium compound in the raw material mixture may be 50 parts by mass or more and 60 parts by mass or more with respect to a total of 100 parts by mass of the cerium compound and the binder from the viewpoint of further improving the adsorption amount of carbon dioxide. It may be 70 mass parts or more, 80 mass parts or more, 85 mass parts or more, or 90 mass parts or more. The content of the cerium compound in the raw material mixture may be 97 parts by mass or less, and 95 parts by mass with respect to a total of 100 parts by mass of the cerium compound and the binder from the viewpoint of improving the adhesion of the adsorbent to the base material. Or 93 parts by mass or less.

  As the binder, at least one selected from the group consisting of an inorganic binder and an organic binder can be used. Examples of the inorganic binder include oxides other than cerium oxide. Examples of the inorganic binder include silica, alumina, zirconia, and the like, and silica can be used from the viewpoint of further improving the adsorption amount of carbon dioxide. As silica, colloidal silica may be used. Examples of the organic binder include epoxy resin and polyamideimide.

  The content of the binder in the raw material mixture may be 3 parts by mass or more and 5 parts by mass or more with respect to a total of 100 parts by mass of the cerium compound and the binder from the viewpoint of improving the adhesion of the adsorbent to the substrate. It may be 7 mass parts or more. The content of the binder in the raw material mixture may be 50 parts by mass or less and 40 parts by mass or less with respect to a total of 100 parts by mass of the cerium compound and the binder from the viewpoint of further improving the carbon dioxide adsorption amount. It may be 30 parts by mass or less, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less.

  The firing temperature in the firing step is not particularly limited as long as it is a temperature at which the cerium compound can be decomposed. The firing temperature may be 150 ° C. or higher, 175 ° C. or higher, or 200 ° C. or higher from the viewpoint of shortening the production time of the adsorbent because decomposition of the cerium compound is likely to proceed. It may be 225 ° C or higher, or 250 ° C or higher. The firing temperature may be 600 ° C. or lower, 500 ° C. or lower, or 400 ° C. or lower from the viewpoint that the specific surface area of the adsorbent tends to increase because sintering of cerium oxide hardly occurs. May be 350 degrees C or less, and 300 degrees C or less may be sufficient. From these viewpoints, the firing temperature may be 150 to 600 ° C, 175 to 500 ° C, 175 to 400 ° C, 200 to 400 ° C, 200 -350 degreeC may be sufficient, 225-300 degreeC may be sufficient, and 250-300 degreeC may be sufficient.

  The firing time in the firing step may be 10 minutes or longer, 1 hour or longer, or 2 hours or longer. The firing time may be 10 hours or less, or 5 hours or less.

  The firing process may be performed in one stage or in multiple stages including two or more stages. In addition, when performing multi-stage baking, it is preferable that at least one stage is the said baking temperature and / or baking time. The firing step can be performed in an air atmosphere, an oxygen atmosphere, or a reducing atmosphere.

<Adsorbent and production method thereof>
The adsorbent (adsorption structure) according to the present embodiment includes a base material (carrier, support) and the adsorbent according to the present embodiment, and the adsorbent adheres to (supports) the base material. The method for producing an adsorbent according to the present embodiment is a method for producing an adsorbent comprising a base material and an adsorbent attached to the base material, the base material, a cerium compound (excluding cerium oxide), and A contact step of contacting the raw material mixture containing the binder, and a firing step of firing the raw material mixture to obtain an adsorbent by the method for producing an adsorbent according to the present embodiment.

  Examples of the shape of the substrate include a plate shape, a honeycomb shape, and a spherical shape. Examples of the material of the substrate include inorganic materials such as silica gel.

  The method for bringing the base material and the raw material mixture into contact in the contacting step is not particularly limited, and examples thereof include a method of spraying a solid or liquid raw material mixture on the base material; a method of immersing the base material in the liquid raw material mixture, and the like. You may dry the base material to which the raw material mixture adhered after the contact process.

  In the method for manufacturing an adsorbent according to the present embodiment, the firing step is performed after the contact step. In the firing step in the method for producing an adsorbent according to this embodiment, the raw material mixture adhering to the base material is fired to obtain an adsorbent. The firing conditions in the firing step are as detailed in the method for producing an adsorbent according to the present embodiment.

<Method for removing carbon dioxide>
The carbon dioxide removal method according to the present embodiment includes an adsorption process in which the adsorbent according to the present embodiment is brought into contact with a processing target gas containing carbon dioxide to adsorb carbon dioxide to the adsorbent.

The CO ₂ concentration in the processing target gas may be 5000 ppm or less (0.5% by volume or less) based on the total volume of the processing target gas. According to the carbon dioxide removal method according to the present embodiment, carbon dioxide can be efficiently removed when the CO ₂ concentration is 5000 ppm or less. The reason why such an effect is achieved is not clear, but the present inventors speculate that it is as follows. In the adsorption step, carbon dioxide is not physically adsorbed on the surface of the cerium oxide, but carbon dioxide is considered to be adsorbed to the adsorbent by chemically bonding with the surface of the cerium oxide. In this case, in the carbon dioxide removal method according to this embodiment, the carbon dioxide partial pressure dependency in the adsorption to the adsorbent is small, and even if the CO ₂ concentration of the gas to be treated is 5000 ppm or less, the carbon dioxide is efficiently removed. It is assumed that carbon can be removed.

CO ₂ concentration from the viewpoint of even if the CO ₂ concentration is low the effect of removing efficiently the carbon dioxide easily identified, based on the total volume of untreated gas may also be 2000ppm or less, 1500 ppm or less It may be 1000 ppm or less, 750 ppm or less, or 500 ppm or less. The CO ₂ concentration may be 100 ppm or more, 200 ppm or more, or 400 ppm or more on the basis of the total volume of the gas to be treated from the viewpoint of easily increasing the amount of carbon dioxide removed. From these viewpoints, the CO ₂ concentration may be 100 to 5000 ppm, 100 to 2000 ppm, 100 to 1500 ppm, or 100 to 1000 ppm, based on the total volume of the gas to be treated. It may be 200 to 1000 ppm, 400 to 1000 ppm, 400 to 750 ppm, or 400 to 500 ppm. In addition, the office hygiene standard rule of the Industrial Safety and Health Law stipulates that the indoor CO ₂ concentration should be adjusted to 5000 ppm or less. In addition, it is known that sleepiness is induced when the CO ₂ concentration exceeds 1000 ppm, and the building environmental hygiene management standard stipulates that the CO ₂ concentration should be adjusted to 1000 ppm or less. Therefore, the CO ₂ concentration may be adjusted by ventilating so that the CO ₂ concentration does not exceed 5000 ppm or 1000 ppm. The CO ₂ concentration in the gas to be treated is not limited to the above range, and may be 500 to 5000 ppm or 750 to 5000 ppm.

The gas to be treated is not particularly limited as long as it contains carbon dioxide, and may contain a gas component other than carbon dioxide. Examples of gas components other than carbon dioxide include water (water vapor, H ₂ O), oxygen (O ₂ ), nitrogen (N ₂ ), carbon monoxide (CO), SOx, NOx, and volatile organic substances (VOC). It is done. Specific examples of the processing target gas include air in a room such as a building or a vehicle. In the adsorption step, when the gas to be treated contains water, carbon monoxide, SOx, NOx, volatile organic matter, etc., these gas components may be adsorbed by the adsorbent.

By the way, in the conventional adsorbents such as zeolite, when the gas to be treated contains water, the CO ₂ adsorptivity tends to be greatly reduced. Therefore, in order to improve the CO ₂ adsorptivity of the adsorbent in the conventional method using the adsorbent, it is necessary to perform a dehumidification step of removing moisture from the target gas before bringing the target gas into contact with the adsorbent. The dehumidifying step is performed using, for example, a dehumidifying device, which leads to an increase in equipment and an increase in energy consumption. On the other hand, the adsorbent according to the present embodiment has excellent CO ₂ adsorptivity compared to conventional adsorbents even when the gas to be treated contains water. Therefore, the carbon dioxide removal method according to the present embodiment does not require a dehumidification step, and carbon dioxide can be efficiently removed even when the gas to be treated contains water.

  The dew point of the gas to be processed may be 0 ° C. or higher. The relative humidity of the gas to be processed may be 30% or more, 50% or more, or 80% or more.

By adjusting the temperature T ₁ of the adsorbent at the time of contact with the adsorbent untreated gas in the adsorption process, it is possible to adjust the amount of adsorption of carbon dioxide. The higher the temperature T _{1, the} lower the amount of CO ₂ adsorbed by the adsorbent. Temperatures _{T 1} may be a -20 to 100 ° C., it may be 10 to 40 ° C..

Temperature T ₁ of the adsorbent may be adjusted by heating or cooling the adsorbent may be used in combination of heating and cooling. Further, the temperature T ₁ of the indirect adsorbent may be adjusted by heating or cooling the processed gas. As a method of heating the adsorbent, a method in which a heat medium (for example, heated gas or liquid) is brought into direct contact with the adsorbent; a heat medium (for example, heated gas or liquid) is circulated through a heat transfer tube, Examples include a method of heating the adsorbent by heat conduction from the heat transfer surface; a method of heating the adsorbent by an electric furnace that generates heat electrically, and the like. As a method for cooling the adsorbent, a method in which a refrigerant (for example, a cooled gas or liquid) is directly brought into contact with the adsorbent; a refrigerant (for example, a cooled gas or liquid) is circulated through a heat transfer tube or the like, and heat transfer is performed. The method of cooling by the heat conduction from a surface etc. is mentioned.

In the adsorption step, the amount of carbon dioxide adsorbed can be adjusted by adjusting the total pressure of the atmosphere in which the adsorbent is present. As the total pressure is higher, the amount of CO ₂ adsorbed by the adsorbent tends to increase. The total pressure may be 1 atm or more from the viewpoint of further improving the carbon dioxide removal efficiency. The total pressure may be 10 atm or less, 2 atm or less, or 1.3 atm or less from the viewpoint of energy saving. The total pressure may be 5 atmospheres or more.

  The total pressure of the atmosphere in which the adsorbent is present may be adjusted by pressurization or depressurization, and pressurization and depressurization may be used in combination. Examples of a method for adjusting the total pressure include a method in which the pressure is mechanically adjusted by a pump, a compressor, and the like; a method in which a gas having a pressure different from the pressure in the ambient atmosphere of the adsorbent is introduced.

In the carbon dioxide removal method according to this embodiment, the adsorbent may be used by being supported on the surface of the substrate, or the adsorbent may be used by filling the inside of the substrate (honeycomb-like substrate). Good. The use method of the adsorbent may be determined in consideration of the required reaction rate, pressure loss, the amount of adsorbent adsorbed, the purity of the gas (adsorbed gas) adsorbed on the adsorbent (CO ₂ purity), and the like.

  In the case of using the adsorbent filled in the base material, when the purity of carbon dioxide in the adsorbed gas is increased, it is preferable that the porosity is smaller. In this case, since the amount of gas other than carbon dioxide remaining in the gap is reduced, the purity of carbon dioxide in the adsorbed gas can be increased. On the other hand, when reducing the pressure loss, it is preferable that the porosity is large.

  The carbon dioxide removal method according to the present embodiment may further include a desorption step of desorbing (desorbing) carbon dioxide from the adsorbent after the adsorption step.

  As a method for desorbing carbon dioxide from the adsorbent, a method using the temperature dependence of the adsorption amount (temperature swing method; a method utilizing the difference in the adsorption amount of the adsorbent with temperature change); Examples include a method of using (pressure swing method, a method of using a difference in the amount of adsorbent adsorbed due to pressure change) and the like, and these methods may be used in combination (temperature / pressure swing method).

  In the method using the temperature dependency of the adsorption amount, for example, the temperature of the adsorbent in the desorption process is set higher than that in the adsorption process. Examples of the method for heating the adsorbent include the same method as the method for heating the adsorbent in the above-described adsorption step; the method using the peripheral exhaust heat, and the like. From the viewpoint of reducing the energy required for heating, it is preferable to use the peripheral exhaust heat.

The temperature difference (T ₂ −T ₁ ) between the adsorbent temperature T ₁ in the adsorption step and the adsorbent temperature T ₂ in the desorption step may be 200 ° C. or less, or 100 ° C. or less from the viewpoint of energy saving. It may be 50 degrees C or less. The temperature difference (T ₂ −T ₁ ) may be 10 ° C. or higher, 20 ° C. or higher, or 30 ° C. or higher from the viewpoint of easy desorption of carbon dioxide adsorbed on the adsorbent. Good. Temperature _{T 2} of the adsorbent in the desorption step, for example, may be 40 to 300 ° C., may be 50 to 200 ° C., may be 80 to 120 ° C..

In the method using the pressure dependency of the adsorption amount, the higher the total pressure in the atmosphere in which the adsorbent is present, the larger the CO ₂ adsorption amount. It is preferable to change it. The total pressure may be adjusted by pressurizing or depressurizing, and pressurization and depressurization may be used in combination. As a method for adjusting the total pressure, for example, a method similar to the adsorption step described above can be used. The total pressure in the desorption process may be the ambient atmospheric pressure (for example, 1 atmosphere) or less than 1 atmosphere from the viewpoint of increasing the amount of CO ₂ desorption.

The carbon dioxide desorbed and recovered by the desorption process may be discharged to the outside as it is, but may be reused in the field using carbon dioxide. For example, in greenhouse cultivation for house or the like, since the plant growth by increasing the CO ₂ concentration is accelerated, because they may increase the CO ₂ concentration 1000ppm level, the recovered carbon dioxide, the CO ₂ concentration May be reused to enhance.

When SOx, NOx, dust, or the like is adsorbed on the adsorbent, the CO ₂ adsorptivity of the adsorbent in the adsorption process may be lowered. Therefore, it is preferable that the gas to be treated does not contain SOx, NOx, dust, or the like. When the gas to be treated contains SOx, NOx, dust, or the like (for example, when the gas to be treated is exhaust gas discharged from a coal-fired power plant or the like), the carbon dioxide removal method according to this embodiment uses adsorption. From the viewpoint of easily maintaining the CO ₂ adsorptivity of the agent, it is preferable to further include an impurity removal step of removing impurities such as SOx, NOx, and dust from the gas to be treated before the adsorption step. In the impurity removing step, the impurities adsorbed on the adsorbent can be removed by heating the adsorbent. The impurity removal step can be performed using a removal device such as a denitration device, a desulfurization device, or a dust removal device, and the gas to be treated can be brought into contact with the adsorbent on the downstream side of these devices. .

  The adsorbent after the desorption process can be used again in the adsorption process. In the carbon dioxide removal method according to this embodiment, the adsorption step and the desorption step may be repeatedly performed after the desorption step. When the adsorbent is heated in the desorption step, the adsorbent may be cooled by the above-described method and used in the adsorption step. The adsorbent may be cooled by bringing a gas containing carbon dioxide (for example, a treatment target gas containing carbon dioxide) into contact with the adsorbent.

The carbon dioxide removal method according to the present embodiment can be preferably carried out in a sealed space where the CO ₂ concentration needs to be managed. Examples of the space in which the CO ₂ concentration needs to be managed include a building, a vehicle, an automobile, a space station, a submersible, a food or chemical production plant, and the like. The carbon dioxide removal method according to this embodiment can be preferably carried out particularly in a space where the CO ₂ concentration is limited to 5000 ppm or less (for example, a space where the density of people such as buildings and vehicles is high). In addition, since carbon dioxide may adversely affect the production of food or chemical products, the carbon dioxide removal method according to the present embodiment is preferably implemented in a food or chemical production plant or the like. Can do.

<Air conditioning equipment and air conditioning system>
The air conditioner according to the present embodiment is an air conditioner used in an air conditioning target space including a processing target gas containing carbon dioxide. The air conditioner according to the present embodiment includes a flow path connected to the air conditioning target space, and a removal unit (carbon dioxide removal unit) that removes carbon dioxide contained in the processing target gas is disposed in the flow path. In the air conditioner according to the present embodiment, the adsorbent according to the present embodiment is disposed in the removal unit, and the adsorbent comes into contact with the processing target gas and carbon dioxide is adsorbed by the adsorbent. According to the present embodiment, there is provided an air conditioning method including an adsorption process in which a processing target gas in an air conditioning target space is brought into contact with an adsorbent to adsorb carbon dioxide to the adsorbent. The details of the processing target gas containing carbon dioxide are the same as the processing target gas in the carbon dioxide removal method described above. Hereinafter, an example of the air conditioner will be described with reference to FIG.

  As shown in FIG. 1, an air conditioner 100 according to this embodiment includes a flow path 10, an exhaust fan (exhaust unit) 20, a concentration measuring device (concentration measuring unit) 30, and an electric furnace (temperature control unit) 40. And a compressor (pressure control means) 50 and a control device (control unit) 60.

  The flow path 10 is connected to the air conditioning target space R including the processing target gas (indoor gas) containing carbon dioxide. The flow path 10 includes a flow path section 10a, a flow path section 10b, a removal section (flow path section, carbon dioxide removal section) 10c, a flow path section 10d, a flow path section (circulation flow path) 10e, The removal part 10c is arrange | positioned at the flow path 10 with the path part (exhaust flow path) 10f. In the flow path 10, a valve 70 a that adjusts the presence or absence of the inflow of the processing target gas in the removing unit 10 c and a valve 70 b that adjusts the flow direction of the processing target gas are arranged.

  The upstream end of the flow path part 10a is connected to the air conditioning target space R, and the downstream end of the flow path part 10a is connected to the upstream end of the flow path part 10b via the valve 70a. The upstream end of the removal part 10c is connected to the downstream end of the flow path part 10b. The downstream end of the removal part 10c is connected to the upstream end of the flow path part 10d. A downstream side of the flow path portion 10d in the flow path 10 is branched into a flow path section 10e and a flow path section 10f. The downstream end of the flow path portion 10d is connected to the upstream end of the flow path portion 10e and the upstream end of the flow path portion 10f via the valve 70b. The downstream end of the flow path part 10e is connected to the air conditioning target space R. The downstream end of the flow path portion 10f is connected to the outside air.

  An adsorbent 80 including the adsorbent according to the present embodiment is disposed in the removing unit 10c. The adsorbent 80 is disposed at the central portion of the removing unit 10c. Two spaces are formed in the removal unit 10c through a space in which the adsorbent 80 is disposed. The removal unit 10c includes an upstream space S1 and a central portion S2 in which the adsorbent 80 is disposed. And a downstream space S3. The space S1 is connected to the air conditioning target space R via the flow path portions 10a and 10b and the valve 70a, and the processing target gas containing carbon dioxide is supplied from the air conditioning target space R to the space S1 of the removal unit 10c. . The processing target gas supplied to the removing unit 10c moves from the space S1 to the space S3 via the central part S2, and is then discharged from the removing unit 10c.

  At least part of the carbon dioxide is removed from the processing target gas discharged from the air conditioning target space R in the removing unit 10c. The processing target gas from which carbon dioxide has been removed may be returned to the air conditioning target space R by adjusting the valve 70b or may be discharged to the outside air outside the air conditioning apparatus 100. For example, the processing target gas discharged from the air conditioning target space R passes from upstream to downstream through the flow path part 10a, the flow path part 10b, the removal part 10c, the flow path part 10d, and the flow path part 10e. Can flow into R. Further, the processing target gas discharged from the air conditioning target space R is discharged from the upstream to the downstream via the flow path part 10a, the flow path part 10b, the removal part 10c, the flow path part 10d, and the flow path part 10f. May be.

  The exhaust fan 20 is disposed at the discharge position of the processing target gas in the air conditioning target space R. The exhaust fan 20 discharges the processing target gas from the air conditioning target space R and supplies it to the removing unit 10c.

  The concentration measuring device 30 measures the carbon dioxide concentration in the air conditioning target space R. The concentration measuring device 30 is disposed in the air conditioning target space R.

  The electric furnace 40 is disposed outside the removing unit 10c of the air conditioner 100, and can raise the temperature of the adsorbent. The compressor 50 is connected to the removing unit 10c of the air conditioner 100, and can adjust the pressure in the removing unit 10c.

  The control device 60 can control the operation of the air conditioner 100. For example, based on the carbon dioxide concentration measured by the concentration measuring device 30, the control device 60 controls the presence or absence of inflow of the processing target gas in the removal unit 10c. be able to. Specifically, when the concentration measuring device 30 detects that the carbon dioxide concentration in the air conditioning target space R has increased and reached a predetermined concentration due to exhalation or the like, concentration information is sent from the concentration measuring device 30 to the control device 60. Sent. The control device 60 that has received the concentration information opens the valve 70a and adjusts the gas discharged from the removal unit 10c so as to flow into the air-conditioning target space R through the flow channel unit 10d and the flow channel unit 10e. And the control apparatus 60 operates the exhaust fan 20, and supplies process target gas from the air-conditioning object space R to the removal part 10c. Furthermore, the control device 60 operates the electric furnace 40 and / or the compressor 50 as necessary to adjust the temperature of the adsorbent, the pressure in the removal unit 10c, and the like.

  When the processing target gas supplied to the removal unit 10c moves from the space S1 to the space S3 via the central portion S2, the processing target gas comes into contact with the adsorbent, and carbon dioxide in the processing target gas is adsorbed by the adsorbent. To do. Thereby, carbon dioxide is removed from the gas to be treated. In this case, the gas from which carbon dioxide has been removed is supplied to the air-conditioning target space R through the flow path part 10d and the flow path part 10e.

  The carbon dioxide adsorbed on the adsorbent may be recovered in a state of being adsorbed on the adsorbent without being desorbed from the adsorbent, or may be recovered after being desorbed from the adsorbent. In the desorption process, by operating the electric furnace 40 and / or the compressor 50 and adjusting the temperature of the adsorbent, the pressure in the removal unit 10c, etc., the above-described temperature swing method, pressure swing method, etc. Carbon dioxide can be desorbed. In this case, for example, the valve 70b is adjusted so that the gas discharged from the removing unit 10c (the gas containing the desorbed carbon dioxide) is discharged to the outside air through the flow path unit 10f. Thus, the discharged carbon dioxide can be recovered.

  The air conditioning system according to the present embodiment includes a plurality of air conditioning apparatuses according to the present embodiment. The air conditioning system which concerns on this embodiment may be provided with the control part which controls the air conditioning driving | operation of several air conditioner. For example, the air conditioning system according to the present embodiment comprehensively controls the air conditioning operation of a plurality of air conditioners.

  For example, as shown in FIG. 2, the air conditioning system 1 according to the present embodiment includes a first air conditioner 100a, a second air conditioner 100b, and a control device (control unit) 62. The control device 62 controls the air conditioning operation of the first air conditioner 100a and the second air conditioner 100b by controlling the above-described control device 60 in the first air conditioner 100a and the second air conditioner 100b. For example, the control device 62 may adjust the air conditioning operations of the first air conditioner 100a and the second air conditioner 100b under the same conditions, and the first air conditioner 100a and the second air conditioner 100b. You may adjust so that air-conditioning operation may be performed on different conditions. The control device 62 can transmit information regarding the presence / absence of inflow of the processing target gas in the removal unit 10c to the control device 60.

  The air conditioner and the air conditioning system are not limited to the above-described embodiment, and may be appropriately changed without departing from the spirit thereof. For example, the control content of the control unit of the air conditioner is not limited to controlling the presence or absence of the inflow of the processing target gas in the removal unit, and the control unit may adjust the inflow amount of the processing target gas in the removal unit.

  In the air conditioner, the gas to be processed may be supplied to the carbon dioxide removing unit using a blower instead of the exhaust fan, and when the gas to be processed is supplied to the carbon dioxide removing unit by natural convection, an exhaust means is provided. It may not be used. Further, the temperature control means and the pressure control means are not limited to the electric furnace and the compressor, and various means described above can be used in the adsorption process and the desorption process. The temperature control means is not limited to the heating means, and may be a cooling means.

  In the air conditioner, each of the air-conditioning target space, the carbon dioxide removal unit, the exhaust unit, the temperature control unit, the pressure control unit, the concentration measurement unit, the control device, etc. is not limited to one, and a plurality of them may be arranged. Good. The air conditioner includes a humidity controller for adjusting the dew point and relative humidity of the gas to be treated; a humidity measuring device for measuring the humidity of the air conditioning target space; a removal device such as a denitration device, a desulfurization device, and a dust removal device. May be.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to a following example.

<Preparation of adsorbent>
Example 1
The cerium carbonate powder 22.64g and the colloidal silica 5.2g (solid content: 40 mass%) were mixed. Next, after adding 57 g of distilled water, the mixture was stirred at 60 rpm for 30 minutes using a mix rotor to obtain a raw material mixture. Subsequently, using a drier, the raw material mixture was dried at 120 ° C. until there was no moisture, thereby obtaining a dried product. The dried product was calcined at 120 ° C. for 1 hour and then calcined at 300 ° C. for 2 hours to obtain an adsorbent.

(Comparative Example 1)
An adsorbent was obtained in the same manner as in Example 1 except that the cerium carbonate powder was changed to a cerium oxide powder and that the dried product was used as an adsorbent without firing after the dried product was obtained. It was.

<Measurement of carbon dioxide adsorption>
The adsorption amount of carbon dioxide was measured using the adsorbents of Examples and Comparative Examples.

  First, the adsorbent was pelletized at 200 kgf by a press using a mold having a diameter of 40 mm. Next, the pellets were crushed and then sized into granules (particle size: 0.5 to 1.0 mm) using a sieve. Thereafter, 1.0 mL of the adsorbent was measured using a graduated cylinder and fixed in a reaction tube made of quartz glass.

  Next, as a pretreatment, the temperature of the adsorbent was raised to 200 ° C. using an electric furnace while flowing helium (He) through the reaction tube at 150 mL / min, and then held at 200 ° C. for 1 hour. Thereby, impurities and gas adsorbed on the adsorbent were removed.

Next, after cooling the adsorbent to 50 ° C., the CO ₂ adsorption amount was measured by a CO ₂ pulse adsorption test while maintaining the adsorbent temperature at 50 ° C. in an electric furnace. Specifically, the CO ₂ pulse adsorption test was performed by the following method.

[CO ₂ pulse adsorption test]
As a sample gas, 10 mL of a mixed gas containing 12% by volume of CO ₂ and 88% by volume of He was used. The sample gas was introduced in a pulsed manner every 4 minutes for 2 minutes. At this time, the total pressure in the reaction tube was adjusted to 1 atmosphere. Next, the CO ₂ concentration at the outlet of the reaction tube was measured by a gas chromatograph (carrier gas: He). The introduction of the sample gas was continued until the CO ₂ concentration measured at the outlet of the reaction tube was saturated. CO ₂ concentration is the amount of carbon dioxide adsorbed in until saturated (unit: g) of the CO ₂ adsorption amount (unit: g / L) was determined.

The CO ₂ adsorption amount of Example 1 was 12.4 g / L. The CO ₂ adsorption amount of Comparative Example 1 was 9.9 g / L. It was confirmed that the CO ₂ adsorption amount of Example 1 was superior to that of Comparative Example 1.

  DESCRIPTION OF SYMBOLS 1 ... Air conditioning system, 10 ... Channel, 10a, 10b, 10d, 10e, 10f ... Channel part, 10c ... Removal part, 20 ... Exhaust fan, 30 ... Concentration measuring device (concentration measuring part), 40 ... Electric furnace, 50 ... Compressor, 60, 62 ... Control device (control unit), 70a, 70b ... Valve, 80 ... Adsorbent, 100, 100a, 100b ... Air conditioner, R ... Air-conditioning target space, S1, S3 ... Space, S2 ... Center Department.

Claims (11)

A method for producing an adsorbent used for removing carbon dioxide from a gas to be treated containing carbon dioxide,
A method for producing an adsorbent, comprising firing a mixture containing a cerium compound (excluding cerium oxide) and a binder to obtain an adsorbent containing cerium oxide.   2. The method for producing an adsorbent according to claim 1, wherein the cerium compound includes at least one selected from the group consisting of cerium carbonate, cerium hydrogen carbonate, cerium oxalate, and cerium hydroxide.   The method for producing an adsorbent according to claim 1, wherein the binder contains silica.   The manufacturing method of the adsorption agent as described in any one of Claims 1-3 which bakes the said mixture at 150 degreeC or more.   The manufacturing method of the adsorption agent as described in any one of Claims 1-3 which bakes the said mixture at 250 degreeC or more. An adsorbent manufacturing method comprising a base material and an adsorbent attached to the base material,
Contacting the substrate with the mixture;
A method for producing an adsorbent comprising: a step of firing the mixture by the method for producing an adsorbent according to any one of claims 1 to 5 to obtain the adsorbent. An adsorbent used to remove carbon dioxide from a gas to be treated containing carbon dioxide,
It is a fired product of a mixture containing a cerium compound (excluding cerium oxide) and a binder,
An adsorbent containing cerium oxide.   The adsorbent according to claim 7, wherein the cerium compound includes at least one selected from the group consisting of cerium carbonate, cerium hydrogen carbonate, cerium oxalate, and cerium hydroxide.   The adsorbent according to claim 7 or 8, further comprising silica. A substrate and the adsorbent according to any one of claims 7 to 9,
An adsorbent, wherein the adsorbent is attached to the substrate.   The adsorbent obtained by the method for producing an adsorbent according to any one of claims 1 to 5, the adsorbent for the adsorbent obtained by the method for producing an adsorbent according to claim 6, and claims 7 to 9 A step of bringing the adsorbent according to any one of claims 1 to 10 or the adsorbent of the adsorbent according to claim 10 into contact with a gas to be treated containing carbon dioxide to adsorb carbon dioxide to the adsorbent. A method for removing carbon dioxide.

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