Adsorbent, gas treatment apparatus, method for producing adsorbent, and method for determining lifetime of adsorbent

Abstract

To provide an adsorbent, a gas treatment apparatus, an adsorbent production method, and an adsorbent lifetime determination method that make it easy to ascertain the lifetime of the adsorbent.SOLUTION: The adsorbent includes a porous body containing silicon dioxide, an inorganic binder, and an acid or a base that generates a salt by a neutralization reaction with a target gas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an adsorbent, a gas treatment device, a method for manufacturing an adsorbent, and a method for determining the lifespan of an adsorbent. [Background technology]

[0002] Research has been conducted into adsorbents that can efficiently remove adsorption targets contained in a fluid to be treated, such as air. For example, Patent Document 1 (JP 2008-080328 A) proposes a filter medium that increases adsorption efficiency while extending the life of the adsorbent. DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0003] In this way, as the adsorbent continues to remove the adsorption target contained in the fluid to be treated, the removal efficiency gradually decreases from its initial value and the adsorbent reaches the end of its life. The adsorbent that has reached the end of its life is replaced with a new adsorbent. Here, it is desirable to be able to easily determine the life of the adsorbent so that it is easy to know when to replace it with a new adsorbent. [Means for solving the problem]

[0004] The adsorbent according to a first aspect includes a porous body, an inorganic binder, and an acid or a base. The porous body includes silicon dioxide. The acid or the base undergoes a neutralization reaction with a target gas to produce a salt.

[0005] When this adsorbent contains an acid, it can treat a basic adsorbate by neutralizing it with a basic adsorbate, and when it contains a base, it can treat an acidic adsorbate by neutralizing it with an acidic adsorbate. Furthermore, since this adsorbent uses a porous material containing silicon dioxide, it is easy to maintain a large specific surface area even in high-temperature environments. Furthermore, the use of a binder in this adsorbent suppresses collapse. Furthermore, since an inorganic binder is used as the binder, when the adsorbent is obtained by heating, it is possible to increase the heating temperature while suppressing deterioration of properties. Thus, since this adsorbent can be heated to a high temperature, collapse of the porous material is suppressed. This makes it easy to visually determine the degree of precipitation of salt generated by the neutralization reaction, making it easier to determine the lifespan of the adsorbent.

[0006] An adsorbent according to a second aspect is the adsorbent according to the first aspect, wherein the porous body includes diatomaceous earth.

[0007] This adsorbent is able to retain a large amount of acid or base due to the porous structure of diatomaceous earth.

[0008] An adsorbent according to a third aspect is the adsorbent according to the first or second aspect, wherein the specific surface area of ​​the porous body is 1 m 2 / g or more 10m 2 / g or less.

[0009] This allows the adsorbent to retain more of the acid or base.

[0010] An adsorbent according to a fourth aspect is the adsorbent according to any one of the first aspect to the third aspect, wherein the target gas is a basic gas, and the adsorbent contains an acid that undergoes a neutralizing reaction with the basic gas.

[0011] The life of this adsorbent is easy to grasp when it is used to adsorb basic gases.

[0012] An adsorbent according to a fifth aspect is the adsorbent according to the fourth aspect, wherein the acid includes polyphosphoric acid.

[0013] This adsorbent is easily capable of retaining acid by impregnation into the porous body.

[0014] An adsorbent according to a sixth aspect is the adsorbent according to any one of the first aspect to the fifth aspect, wherein the binder contains silica.

[0015] This adsorbent can suppress changes in the properties of the binder when heated.

[0016] A gas treatment device according to a seventh aspect includes the adsorbent according to any one of the first to sixth aspects and a casing. The casing accommodates the adsorbent therein. The casing has a window through which the adsorbent can be viewed.

[0017] This gas treatment device makes it possible to visually check from the outside the device the degree of precipitation of salts produced by the neutralization reaction.

[0018] A method for producing an adsorbent according to an eighth aspect includes a mixing step, a heating step, and an adhering step. In the mixing step, a porous body containing silicon dioxide is mixed with a binder to obtain a mixture. In the heating step, the mixture is heated at an ambient temperature of 250°C or higher to obtain a heated body. In the adhering step, an acid or a base is adhered to the heated body. The acid or base undergoes a neutralization reaction with the target gas to produce a salt.

[0019] This method for producing an adsorbent can treat a basic adsorbate by neutralizing an acidic adsorbate with a basic adsorbate, and can treat an acidic adsorbate by neutralizing a base with an acidic adsorbate. This adsorbent uses a porous material containing silicon dioxide, which makes it easy to maintain a large specific surface area even in high-temperature environments. Furthermore, in the mixing step, the porous material and binder are mixed, which makes it possible to suppress the collapse of the resulting adsorbent. The mixture of the porous material and binder is heated to 250°C or higher in a heating step performed before the acid or base attachment step to form a heated body. This makes it possible to obtain a heated body that is resistant to collapse. Furthermore, heating to 250°C or higher before the acid or base attachment step prevents the acid or base from disappearing or denaturing due to heating. This makes it easy to visually assess the degree of salt precipitation generated by the neutralization reaction, thereby enabling the production of an adsorbent whose lifespan is easily determined.

[0020] A ninth aspect of the present invention provides a method for determining the lifespan of an adsorbent by visually checking the degree of precipitation of a salt resulting from a neutralization reaction. The adsorbent includes a porous body, a binder, and an acid or a base. The porous body includes silicon dioxide. The acid or base neutralizes a target gas to produce a salt.

[0021] In this method for determining the lifespan of an adsorbent, if the adsorbent contains an acid, it can treat the basic adsorbate by undergoing a neutralization reaction with the basic adsorbate, and if the adsorbent contains a base, it can treat the acidic adsorbate by undergoing a neutralization reaction with the acidic adsorbate. Here, since this adsorbent uses a porous material containing silicon dioxide, it is easy to maintain a large specific surface area even in high-temperature environments. Furthermore, the porous material is fixed with a binder, which prevents the adsorbent from collapsing. This makes it easy to visually determine the degree of precipitation of salt generated by the neutralization reaction and to determine the lifespan of the adsorbent.

[0022] In a method for determining the lifetime of an adsorbent according to a tenth aspect, the salt is white, and the porous body is a different color from the salt.

[0023] In this method for determining the lifespan of an adsorbent, the color of the porous body differs from the color of the precipitated salt, making it easier to see the amount of precipitated salt. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of a gas treatment device. [Figure 2] FIG. [Figure 3] 10 is a photograph showing the state of a sample corresponding to the elapsed time in an adsorption breakthrough test. DETAILED DESCRIPTION OF THE INVENTION

[0025] The adsorbent, gas treatment device, method for manufacturing an adsorbent, and method for determining the life of an adsorbent according to the embodiments will be described below with examples.

[0026] (1) Adsorbent The adsorbent of this embodiment includes a porous body, a binder, and an acid or a base.

[0027] The fluid to be treated containing the gas to be adsorbed is preferably a gas.

[0028] (1-1) Porous body The porous body preferably has a plurality of pores and mainly contains silicon dioxide. The weight ratio of silicon dioxide in the porous body may be 50% by weight or more, more preferably 90% by weight or more, and even more preferably 99% by weight or more. Such porous bodies mainly containing silicon dioxide may be, for example, diatomaceous earth, silica gel, mesoporous silica, or mixtures thereof. Among these, diatomaceous earth is preferred from the viewpoint of easy retention of acid or base. Silicon dioxide is preferred for adsorbents obtained by heating, such as calcination, from the viewpoint of maintaining its porous nature and large specific surface area even in high-temperature environments.

[0029] The specific surface area of ​​a porous material is 1m 2 / g or more 10m 2 / g or less is preferable.

[0030] The color of the porous body is preferably different from the color of the precipitated salt in order to enhance the visibility of the precipitated salt. The different color may be any color that can be recognized by a person with normal eyesight as being different from the color of the precipitated salt at a distance of 1 meter or less. The color of the porous body is preferably a color other than white, and may be, for example, brown, black, gray, etc. Even if the precipitated salt crystals are transparent, the salt crystals precipitated in the adsorbent are perceived as white or whitish to the naked eye due to diffuse reflection of light. When diatomaceous earth is used as the porous body, it is possible to make the porous body a color different from the color of the precipitated salt without coloring the porous body.

[0031] From the viewpoint of suppressing combustibility in a high-temperature environment, it is preferable that the porous body does not contain carbon such as activated carbon.

[0032] Furthermore, since the color of the salt precipitated by neutralization is similar to that of the salt, which makes it difficult to see the salt, it is preferable that the porous body does not contain zeolite.

[0033] (1-2) Binder The binder increases the strength of the porous body and can suppress the collapse of the porous body, which prevents the adsorbent from collapsing when handled, thereby improving the handleability of the adsorbent.

[0034] As the binder, for example, an organic binder or an inorganic binder can be used. Examples of organic binders include cellulose derivatives such as methyl cellulose, ethyl cellulose, propyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, and hydroxyethyl cellulose, polyvinyl alcohol, and acrylic resins. Examples of inorganic binders include silica and alumina. Among these, for adsorbents obtained through a heating process, it is preferable to use an inorganic binder, as this can suppress deterioration or denaturation of the binder in a high-temperature environment due to heating and allows for an increase in the heating temperature. Among inorganic binders, silica is more preferable, as it suppresses a decrease in adsorption efficiency. Furthermore, silica as a binder is preferable because it produces a small amount of outgassing even when used as a component constituting the adsorbent.

[0035] The weight ratio of the inorganic binder in the adsorbent is, for example, preferably 5% by weight or more and 15% by weight or less, and more preferably 8% by weight or more and 12% by weight or less.

[0036] (1-3) Acid When the target of adsorption by the adsorbent is a basic substance, the acid neutralizes the basic substance to generate a salt, which decomposes the basic substance to be adsorbed by the adsorbent, thereby reducing the proportion of the basic substance in the treated fluid.

[0037] Such an acid is retained in the pores of the porous body of the adsorbent. The acid can be retained in the porous body, for example, by impregnating the porous body with the acid.

[0038] The acid is not particularly limited as long as it generates a salt by neutralizing with a basic target to be adsorbed, and examples thereof include polyphosphoric acid, phosphoric acid, sulfuric acid, nitric acid, oxalic acid, citric acid, etc. Among these, polyphosphoric acid or phosphoric acid is preferred, and polyphosphoric acid is more preferred, from the viewpoints of ease of retention by impregnation into a porous body and high stability in the adsorbent.

[0039] The basic gas to be adsorbed, which undergoes a neutralizing reaction with an acid, is not particularly limited, and examples thereof include ammonia and trimethylamine.

[0040] The weight ratio of the acid in the adsorbent can be, for example, from 5% by weight to 45% by weight, and preferably from 20% by weight to 40% by weight.

[0041] In addition, the adsorbent with acid attached is ammonia gas of 200 ppm with an SV value of 53,000 h. -1 In the adsorption test used in the above, it is preferable that the time required for the gas removal rate to decrease to 85% or less is 5 hours or more.

[0042] (1-4) Base When the target of adsorption by the adsorbent is an acidic target, the base neutralizes the target to produce a salt, which decomposes the acidic target, thereby reducing the proportion of the acidic target in the treated fluid.

[0043] Such a base is retained in the pores of the porous body of the adsorbent. The base can be retained in the porous body, for example, by impregnating the porous body with the base.

[0044] The base is not particularly limited as long as it generates a salt by neutralizing with the acidic target to be adsorbed, and examples thereof include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, potassium phosphate, etc. Among these, sodium hydroxide or potassium hydroxide is preferred from the viewpoints of ease of retention by impregnation in a porous body and high stability in the adsorbent.

[0045] The acidic gas to be adsorbed, which undergoes a neutralizing reaction with a base, is not particularly limited, and examples thereof include hydrogen sulfide, methyl mercaptan, and sulfur dioxide.

[0046] (2) Manufacturing method of adsorbent The method for producing the adsorbent includes a mixing step, a heating step, and an adsorption step.

[0047] In the mixing step, a porous body containing silicon dioxide and a binder are mixed to obtain a mixture. In the mixing step of the porous body and the binder, it is preferable to obtain a mixture formed into pellets by granulation after kneading. Note that the porous body and the binder can be those described in (1) above. As the binder, it is preferable to use an inorganic binder, from the viewpoint of suppressing deterioration or denaturation of the binder even when the strength is increased by increasing the heating temperature when the mixture obtained by mixing is heated and fired.

[0048] In the heating step, the mixture obtained in the mixing step is heated at an ambient temperature of 250°C or higher to obtain a heated body. In the heating step, the mixture is preferably calcined by heating at an ambient temperature of 250°C or higher for a predetermined period of time or longer. The heating temperature is 250°C or higher, preferably 280°C or higher, more preferably 300°C or higher, and may be 330°C or higher or 350°C or higher, from the viewpoint of increasing the strength of the heated body and making it less likely to collapse. The heating temperature can be 400°C or lower, from the viewpoint of not contributing to an increase in the strength of the heated body and minimizing the energy consumption required for heating. Note that, since the heating step is performed before the acid or base is attached in the attachment step described below, the thermal decomposition, degradation, or denaturation of the acid or base retained in the final adsorbent is suppressed even if the adsorbent is heated at a temperature higher than the heating temperature at which the acid or base thermally decomposes, deteriorates, or denatures.

[0049] In the attachment step, an acid or a base is attached to the heated body obtained in the heating step. The acid or base is one that undergoes a neutralization reaction with the target gas to produce a salt, and those described in (1) above can be used. In the acid or base attachment step, the heated body is preferably impregnated with the acid or base and dried at a temperature lower than the heating temperature in the heating step to attach the acid or base. The ambient temperature during this drying treatment is, for example, 80°C or higher and 200°C or lower. By keeping the temperature during the drying treatment lower than the heating temperature in the heating step, thermal decomposition, deterioration, or denaturation of the acid or base attached to the heated body is suppressed.

[0050] The adsorbent obtained by the above steps has high strength and is resistant to disintegration, so that the salt precipitated by the neutralization reaction during use is prevented from mixing with the disintegrated material, and the visibility of the precipitated salt is improved. This improves the visibility of the level of precipitated salt in the adsorbent, making it easier to determine the lifespan of the adsorbent.

[0051] (3) Method for determining the lifespan of adsorbents The method for determining the lifespan of an adsorbent is to visually check the degree of precipitation of salts that precipitate due to a neutralization reaction. The adsorbent includes a porous body, a binder, and an acid or a base. The porous body includes silicon dioxide. The acid or base produces a salt by undergoing a neutralization reaction with the target gas. The porous body, binder, acid, or base described in (1) above can be used.

[0052] In the lifespan determination method, the greater the amount of salt precipitated by the neutralization reaction, the closer the lifespan is to being determined, and the smaller the amount of salt precipitated by the neutralization reaction, the longer the lifespan is to be determined.

[0053] As described in (1) above, the color of the porous body is preferably different from the color of the precipitated salt, from the viewpoint of enhancing the visibility of the precipitated salt, and is preferably a color other than white, such as brown, black, gray, etc.

[0054] (4) Gas treatment equipment The gas treatment device includes the adsorbent described in (1) above and a casing. The gas treatment device and the adsorbent can be used in clean rooms in semiconductor manufacturing factories and the like.

[0055] The casing accommodates the adsorbent inside. The casing has a window through which the adsorbent can be viewed. The window may be an opening provided in the casing or a plate-like member made of a transparent material.

[0056] The casing has a flow path in which, for example, an inlet for introducing the fluid to be treated, an adsorbent, and an outlet for discharging the treated fluid are arranged side by side. Here, the window provided in the casing is preferably provided at a position that allows visibility of the adsorbent from a direction that intersects with the direction in which the fluid to be treated passes through the flow path, and may be provided around the adsorbent.

[0057] Specifically, the gas treatment device 1 may include a casing 10 and an adsorbent 5 housed within the casing 10, as in the gas treatment device 1 shown in FIG. 1 . The casing 10 has an inlet 11, a window 13, and an outlet 12. The inlet 11, the window 13, and the outlet 12 are arranged in this order in the flow direction of the fluid to be treated, as indicated by the arrows. The adsorbent 5 is housed within the casing 10 at a position overlapping the window 13 when viewed in a direction perpendicular to the flow direction of the fluid to be treated, as indicated by the arrows. The window 13 is made of optically transparent glass, resin, or the like, so that the adsorbent 5 can be seen when viewed from a direction intersecting the flow direction of the fluid to be treated, as indicated by the arrows.

[0058] This allows the degree of salt precipitation in the adsorbent 5 to be visually confirmed from outside the casing 10, making it possible to easily grasp the lifespan without removing the adsorbent 5 from the casing 10 or analyzing the removed adsorbent 5 using a lifespan analysis device. [Example]

[0059] Hereinafter, examples and comparative examples will be shown to explain the present disclosure while giving specific examples.

[0060] Example 1 A mixture was obtained by kneading brown diatomaceous earth (manufactured by Tsuchida Foods Industries Co., Ltd., product name "Toro Ichiban No. 2") as a porous material with silica sol (manufactured by Nissan Chemical Industries, Ltd., product name "Snowtex") as a binder in a weight ratio of 54:46. Since the weight ratio of the binder in Snowtex was 20% by weight, the weight ratio of diatomaceous earth to binder was 85.4:14.6. The mixture was then granulated using a granulator (DALTON Multigran) to produce cylindrical pellets with a diameter of 3 mm and a length of 3 mm. The mixture was then heated for 1 hour in an ambient temperature of 300°C to obtain a fired product. The fired product was then impregnated with polyphosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "Polyphosphoric Acid") as an acid and dried for 1 hour in an ambient temperature of 175°C to obtain the adsorbent of Example 1.

[0061] (Comparative Example 1) A mixture was obtained by kneading diatomaceous earth (manufactured by Tsuchida Foods Industries Co., Ltd., product name "Toro Ichiban No. 2") as a porous material, silica sol (manufactured by Nissan Chemical Industries, Ltd., product name "Snowtex") as a binder, and polyphosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "Polyphosphoric Acid") as an acid in a weight ratio of 35:30:35. The weight ratio of the binder in Snowtex was 20% by weight, and the weight ratio of polyphosphoric acid in the polyphosphoric acid reagent was 80% by weight, so the weight ratio of diatomaceous earth to binder to acid was 50.7:8.7:40.6. The mixture was then granulated using a granulator (DALTON Multigran) to produce cylindrical pellets measuring 3 mm in diameter and 3 mm in length. The mixture was then dried for 1 hour at an ambient temperature of 200°C to obtain the adsorbent of Comparative Example 1.

[0062] (Crushing test) Each of the adsorbents obtained as described above was subjected to a crushing test to evaluate its crumbling tendency. In the crushing test, a load was applied to the adsorbent as described below, in accordance with the Japan Powder Process Industry Association Standard G001, and the crumbling tendency was evaluated by observing how it broke.

[0063] Specifically, a cylindrical pellet 50 having a diameter of 3 mm and a length of 3 mm was used, and a load was applied in a direction perpendicular to the axial direction of the cylinder using the apparatus shown in FIG. 2 to crush the pellet. Specifically, one sample pellet was placed at the center of the lower compression surface 42 extending from the upper surface of the lower pressure plate 41, and a load was applied to the sample by moving the upper compression surface 32 extending from the lower surface of the upper pressure plate 31 toward the lower compression surface 42 at a constant pressure plate speed. Here, the pressure plate speed was 20 mm / min. The highest reading until the sample was completely crushed was recorded and used as the crushing strength value.

[0064] In Example 1 and Comparative Example 1, the air in the unused state was adjusted to a temperature of 25°C, a humidity of 50 to 60% RH, and an ammonia concentration of 200 ppm, and the SV (Space Velocity) value was 53,000 h -1 A crushing test was carried out on both the used and the used ones, which had been continuously flushed for 10 days so that the

[0065] According to the above, in Comparative Example 1, the crushing strength value of the unused product was 2 kg / particle, while the crushing strength value of the used product was less than 1 kg / particle, confirming a decrease of more than 1 kg / particle. In contrast, in Example 1, the crushing strength value of the unused product was 2.6 kg / particle, while the crushing strength value of the used product was less than 2.7 kg / particle, showing almost no change, and it was confirmed that the product was less likely to collapse even when used than Comparative Example 1.

[0066] (Adsorption breakthrough test) The adsorbents of Example 1 and Comparative Example 1 were subjected to the adsorption breakthrough test described below to evaluate their life spans.

[0067] Specifically, the adsorbent was made by molding multiple pellets into a cylindrical shape with a diameter of 25 mm and a length of 32 mm. Air adjusted to a temperature of 25°C, humidity of 25-70%, and an ammonia concentration of 200 ppm was blown onto the pellets, with a SV (Space Velocity) value of 53,000 h -1 The ammonia concentration of the air was measured upstream and downstream of the adsorbent. The time required for the ammonia adsorption efficiency of the adsorbent, calculated based on the following formula (1), to decrease to 85% after the start of flowing the ammonia-containing air through the adsorbent (breakthrough time) was evaluated as the lifespan. The breakthrough times were 5.4 hours for Example 1 and 5.7 hours for Comparative Example 1, which were similar, and no significant difference was observed. Adsorption efficiency (%) = {1-(downstream ammonia concentration / upstream ammonia concentration)} × 100 … (1)

[0068] FIG. 3 shows photographs of the appearance of the adsorbent after 15, 30, 60, 120, and 180 minutes of flow of ammonia-containing air into the adsorbent. It was confirmed that the polyphosphoric acid contained in the adsorbent neutralized with the ammonia contained in the treated fluid, resulting in the precipitation of white salt. It was also confirmed that the adsorbent of Example 1 was prevented from collapsing during use, preventing the salt precipitate from mixing with the adsorbed material, making the salt precipitate easily visible. The adsorption efficiencies (%) at 15, 30, 60, 120, and 180 minutes were 99%, 98%, 93%, 42%, and 0%, respectively.

[0069] Example 2 The adsorbent of Example 2 was obtained in the same manner as in Example 1, except that hydraulic alumina (manufactured by Sumitomo Chemical Co., Ltd., product name "Hydraulic Alumina") was used as the binder. Since the weight ratio of the binder in the hydraulic alumina was 30 wt%, the weight ratio of diatomaceous earth to the binder was The ratio was 79.4 to 20.6.

[0070] As mentioned above, the crushing strength value of unused Example 1 was 2.6 kg / particle, while the crushing strength value of unused Example 2 was 3.8 kg / particle. However, the breakthrough time (lifespan) of Example 1 was 5.4 hours, while the breakthrough time (lifespan) of Example 2 was 0.7 hours. From the above, it was confirmed that silica is desirable as a binder for increasing lifespan.

[0071] (Addendum) Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0072] 1 Gas treatment equipment 5. Adsorbents 10 Casing 13. Windows [Prior art documents] [Patent documents]

[0073] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-080328

Claims

1. a porous body containing silicon dioxide; an inorganic binder; An acid or base that neutralizes with the target gas to form a salt, an adsorbent (5) comprising:

2. The porous body includes diatomaceous earth. The adsorbent of claim 1.

3. The specific surface area of ​​the porous body is 1 m ２ / g or more 10m ２ / g or less, The adsorbent according to claim 1 or 2.

4. the target gas is a basic gas, The acid reacts with the basic gas to neutralize the gas. The adsorbent according to claim 1 or 2.

5. The acid includes polyphosphoric acid. The adsorbent according to claim 4.

6. The binder includes silica. The adsorbent according to claim 1 or 2.

7. an adsorbent (5) according to claim 1 or 2; a casing (10) that accommodates the adsorbent therein and has a window (13) through which the adsorbent can be viewed; A gas treatment device (1) comprising:

8. a mixing step of mixing a porous body containing silicon dioxide with a binder to obtain a mixture; a heating step of heating the mixture at an ambient temperature of 250°C or higher to obtain a heating body; an attachment step of attaching an acid or a base to the heating body to form a salt by neutralizing with the target gas; A method for producing an adsorbent (5) comprising:

9. A method for determining the lifespan of an adsorbent (5), comprising: The adsorbent includes a porous body containing silicon dioxide, a binder, and an acid or a base that undergoes a neutralization reaction with the target gas to produce a salt, The lifespan is determined by visually checking the degree of precipitation of salt precipitated by the neutralization reaction. Method for determining the lifespan of adsorbents.

10. The salt is white in color; The porous body is a different color from the salt. The method for determining the lifespan of an adsorbent according to claim 9.

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