Composite gas adsorbent, method for producing composite gas adsorbent, composite gas removal method, deodorizing filter, and air purifier

Abstract

To provide a composite gas adsorbent, a method for producing the composite gas adsorbent, a deodorizing filter, and an air purifier, which are capable of removing, in a well-balanced manner and rapidly, a composite gas containing more than one of aldehyde odor substances, basic odor substances, acidic odor substances and volatile organic compounds existing in the environment.SOLUTION: A composite gas adsorbent comprises activated carbon, where 3-30 mass% of 2-imidazolidinone and 3-30 mass% of phosphoric acid are supported on the activated carbon, and potassium is contained in an amount of 0.1 mass fraction% or more. The adsorbent has an acetone equilibrium adsorption performance of 12.0 mass fraction% or more, measured using acetone at a concentration of 37.5 g / m3 in conformity with JIS K 1474 (2014). The adsorbent has adsorption performance with respect to a composite gas containing more than one aldehyde odor substances, basic odor substances, acidic odor substances and volatile organic compounds.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composite gas adsorbent that adsorbs a composite gas containing multiple odorous substances, a method for manufacturing the composite gas adsorbent, a method for removing the composite gas using the composite gas adsorbent, a deodorizing filter using the composite gas adsorbent, and an air purifier using the deodorizing filter. [Background technology]

[0002] Odorants present in living and working environments include acidic odorants, neutral odorants, basic odorants, volatile organic compounds, and aldehyde odorants. Haze, which is caused by smoke from large-scale open burning and forest fires in Southeast Asian countries such as Malaysia and Singapore, is a complex gas containing multiple of the above odorants, and acidic odorants such as sulfur dioxide (SO2) are designated as indicators of the air pollution level in the API (Air Pollutant Index) and PSI (Pollutant Standard Index), and there is a high demand for their removal.

[0003] Conventionally, adsorbents for aldehyde-based odorous substances have been used, for example, in which a compound that reacts with an aldehyde compound is supported on a porous material such as activated carbon or zeolite.

[0004] For example, Patent Document 1 describes an adsorbent for lower aldehydes, which comprises activated carbon on which a surface oxide has been formed by oxidation treatment and which supports a cyclic saturated secondary amine (a).

[0005] Patent Document 2 describes an adsorbent for lower aldehydes in which 5 to 30% by weight of a cyclic urea compound (2-imidazolidinone) and 5 to 15% by weight of an inorganic acid or an organic acid are supported on activated carbon. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-84406 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-232189 Summary of the Invention [Problem to be solved by the invention]

[0007] Since a wide variety of odorous gases exist in living environments, particularly indoor environments, there is a growing demand for gas adsorbents that can remove not only aldehyde-based odorous substances but also each odorous gas in a balanced and rapid manner.

[0008] Gas-phase applications, particularly air purifier applications, require clean air delivery rate (CADR) performance, a standard established by the Association of Home Appliance Manufacturers (AHAM) that is an index showing the amount of clean air an air purifier supplies per minute. The market demands performance in terms of how quickly clean air can be delivered, and the adsorbents used are required to have not only adsorption capacity but also adsorption speed.

[0009] The adsorbent described in Patent Document 1 is said to adsorb and remove lower aldehydes, but its removal effect on basic odorous substances and sulfur compounds (acidic odorous substances) such as sulfur dioxide (SO2) is unknown.

[0010] The adsorbent described in Patent Document 2 uses 2-imidazolidinone as the cyclic urea compound, but because 2-imidazolidinone is a basic substance, there is a risk that it will be deactivated by a neutralization reaction when mixed with a large amount of inorganic or organic acid. Furthermore, the adsorbent described in Patent Document 2 is described as having excellent removal performance for lower aldehydes, but its removal effect on sulfur compounds (acidic odorous substances) such as sulfur dioxide (SO2) is unknown.

[0011] The Korean Air Purifier Association (KACA) standard (SPS-KACA002-132) is a standard for odorant adsorption. According to this standard, the standard is for an 8m air filter containing ammonia, toluene, and formaldehyde gases. 3 Clean air supply rate (CADR; m 3 / h) is required to have a certain level of initial performance or higher. Therefore, there is a growing demand for gas adsorbents that can achieve a certain level of adsorption speed while satisfying a certain level of adsorption capacity for complex gases that include not only aldehydes (aldehyde-based odorous substances) but also other odorous substances.

[0012] Therefore, an object of the present invention is to provide a composite gas adsorbent, a method for manufacturing the composite gas adsorbent, a deodorizing filter, and an air purifier that are capable of quickly and in a balanced manner removing composite gases that contain multiple aldehyde odorants, basic odorants, acidic odorants, and volatile organic compounds present in the environment. [Means for solving the problem]

[0013] The composite gas adsorbent according to the present invention for achieving the above object has a characteristic configuration including activated carbon, in which 3 to 30 mass % of 2-imidazolidinone and 3 to 30 mass % of phosphoric acid are supported on the activated carbon, and the composite gas adsorbent contains potassium at a concentration of 0.1 mass fraction % or more, in accordance with JIS K 1474 (2014), at a concentration of 37.5 g / m 3 The acetone equilibrium adsorption capacity measured using acetone is 12.0 mass fraction % or more, and the adsorption capacity is for a complex gas containing two or more of aldehyde odorous substances, basic odorous substances, acid odorous substances, and volatile organic compounds.

[0014] As mentioned above, there are many gas adsorbents for aldehydes. However, it has been difficult to rapidly remove basic odorous substances, aldehyde-based odorous substances, and volatile organic compounds, which can be removed by chemical adsorption, using a single gas adsorbent.

[0015] By setting the amount of 2-imidazolidinone carried within the above range, odorous substances that can be adsorbed by chemical adsorption can be adsorbed efficiently.

[0016] By supporting phosphoric acid together with 2-imidazolidinone on activated carbon, the adsorption rate of aldehyde odorous substances can be improved. By setting the amount of phosphoric acid supported within the above range, odorous substances that can be adsorbed by chemical adsorption, particularly basic odorous substances, can be efficiently adsorbed.

[0017] By setting the potassium content within the above range, the catalytic action improves the physical adsorption performance of acidic odorous substances in particular, and acidic odorous substances can be adsorbed efficiently.

[0018] When the equilibrium adsorption performance of acetone satisfies the above range, the physical adsorption performance of acidic odorous substances and volatile organic compounds adsorbed by physical adsorption is improved.

[0019] As in the present configuration, it has been found that by supporting 3 to 30 mass % of 2-imidazolidinone and 3 to 30 mass % of phosphoric acid on the activated carbon, and containing potassium at a mass fraction of 0.1% or more, and making the equilibrium adsorption performance for acetone 12.0 mass fraction % or more, it is possible to efficiently adsorb aldehyde odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds (Examples described later).

[0020] Therefore, the composite gas adsorbent of the present invention has particularly excellent adsorption performance for aldehyde odorants and basic odorants that can be removed by chemical adsorption, and acid odorants and volatile organic compounds that can be removed by physical adsorption, and has a certain level of adsorption capacity and also meets the adsorption speed, making it possible to quickly remove composite gases that contain several of these in a balanced manner.

[0021] A further characteristic feature of the composite gas adsorbent according to the present invention is that the mass ratio of the phosphoric acid to the 2-imidazolidinone is 0.5 or more.

[0022] This configuration provides excellent adsorption performance, particularly for sulfur dioxide.

[0023] A further characteristic feature of the composite gas adsorbent according to the present invention is that the pH of an aqueous suspension of the composite gas adsorbent, measured in accordance with JIS K 1474 (2014), is greater than 2.0.

[0024] According to this configuration, by satisfying the pH range, both basic odorous substances and acidic odorous substances can be efficiently adsorbed.

[0025] A further characteristic feature of the composite gas adsorbent according to the present invention is that the potassium is contained in an amount of 2.40 mass fraction % or less.

[0026] According to this configuration, by setting the potassium content within the above range, acidic odorous substances can be adsorbed more efficiently.

[0027] A further characteristic feature of the composite gas adsorbent according to the present invention is that the packing density is 0.710 g / mL or less.

[0028] According to this configuration, by ensuring that the packing density falls within the range, it is possible to efficiently adsorb both acidic odorous substances and volatile organic compounds.

[0029] A characteristic feature of the method for producing a composite gas adsorbent according to the present invention is that it includes a preparation step of preparing an aqueous solution by dissolving powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and powdered or particulate potassium compound in water, and a supporting step of bringing the aqueous solution into contact with activated carbon to cause the activated carbon to support the aqueous solution.

[0030] The preparing step can prepare an aqueous solution by dissolving powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and powdered or particulate potassium compound in water, or can separately prepare aqueous solutions by dissolving one or more of powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and powdered or particulate potassium compound in water.

[0031] In the supporting step, the aqueous solution is brought into contact with the activated carbon, whereby 2-imidazolidinone, phosphoric acid, and a potassium compound can be supported evenly over the entire activated carbon.

[0032] Therefore, according to this configuration, it is possible to produce a composite gas adsorbent that has particularly excellent adsorption performance for composite gases containing aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds, meets a certain level of adsorption capacity and adsorption speed, and is capable of quickly removing composite gases containing several of these substances in a balanced manner.

[0033] A further characteristic feature of the method for producing a composite gas adsorbent according to the present invention is that the potassium compound is potassium iodide or potassium carbonate.

[0034] According to this configuration, a potassium compound that is easily available can be used, and therefore the method for producing the composite gas adsorbent of the present invention can be easily carried out.

[0035] The characteristic feature of the complex gas removal method of the present invention is that it uses the above-mentioned complex gas adsorbent to remove any one or more odorous substances from an indoor environment, including aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds.

[0036] According to this configuration, by bringing the composite gas adsorbent into contact with the indoor atmosphere containing any one of the above-mentioned multiple odorous substances, the composite gas adsorbent comes into contact with the odorous substances, and can efficiently adsorb and remove any one of the above-mentioned multiple odorous substances.

[0037] The deodorizing filter for an air purifier according to the present invention is characterized by the use of the above-mentioned composite gas adsorbent.

[0038] According to this configuration, it is possible to provide a deodorizing filter for an air purifier that has particularly excellent adsorption performance for complex gases containing aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds, and that meets a certain level of adsorption capacity and adsorption speed.

[0039] The air purifier according to the present invention is characterized by the use of the above-described deodorizing filter.

[0040] According to this configuration, an air purifier can be provided that has particularly excellent adsorption performance for complex gases containing aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds, and that meets a certain level of adsorption capacity and adsorption speed. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a flow chart showing a method for producing a composite gas adsorbent according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0042] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The composite gas adsorbent of the present invention has adsorption performance for a composite gas containing multiple odorous substances present in the environment. The composite gas adsorbent has activated carbon, and the activated carbon supports 3 to 30 mass% of 2-imidazolidinone and 3 to 30 mass% of phosphoric acid, and contains potassium at a concentration of 0.1 mass% or more, and is measured in accordance with JIS K 1474 (2014) at a concentration of 37.5 g / m 3 The equilibrium adsorption capacity of the acetone measured using acetone is 12.0 mass fraction % or more, and the acetone adsorption capacity is high for a complex gas containing multiple aldehyde odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds.

[0043] (composite gas) The composite gas adsorbent of the present invention has adsorption performance for a composite gas containing a plurality of aldehyde odorants, basic odorants, acidic odorants, and volatile organic compounds, i.e., at least two of these.

[0044] Examples of aldehyde odorants include, but are not limited to, formaldehyde, acetaldehyde, propionaldehyde, acrolein, n-butyraldehyde, isobutyraldehyde, pentanal, hexanal, heptanal, octanal, nonenal, decanal, 3-methylbutyraldehyde, crotonaldehyde, and 2,4-heptadienal.

[0045] Examples of basic odorous substances include, but are not limited to, ammonia, alkylamines (trimethylamine, triethylamine, etc.), aromatic amines (pyridine, etc.), and organic amine compounds that have an odor other than those mentioned above.

[0046] Examples of acidic odor compounds include, but are not limited to, sulfur oxides (SOx) such as sulfur monoxide and sulfur dioxide, nitrogen oxides (NOx) such as nitrogen monoxide and nitrogen dioxide, hydrogen sulfide, and methyl mercaptan.

[0047] Volatile organic compounds (VOCs) are organic chemical molecules that have a high vapor pressure at room temperature, including, but not limited to, toluene, acetic acid, formaldehyde, benzene, xylene, ethylbenzene, styrene, propane, hexane, cyclohexane, limonene, pinene, acetaldehyde, hexaldehyde, ethyl acetate, and butanol.

[0048] (activated carbon) Activated carbon refers to a material with a structure in which many pores are formed. Because many pores are formed in activated carbon, it has a large specific surface area. The size of the pores in activated carbon is not particularly limited, but can be, for example, 0.1 to 200,000 nm.

[0049] Pores in activated carbon are classified according to their diameter into micropores (<2 nm), mesopores (2-50 nm), and macropores (>50 nm), and gas adsorption methods are generally used to measure micropores and mesopores.

[0050] Volatile organic compounds such as toluene and acetic acid are generally believed to be removed by activated carbon through physical adsorption, and activated carbon with developed micropores tends to be suitable. Basic odorants such as ammonia and aldehyde odorants such as formaldehyde and acetaldehyde are generally believed to be removed by activated carbon through chemical adsorption. Furthermore, by using activated carbon with developed micropores, it is possible to support more 2-imidazolidinone and phosphoric acid, which contribute to chemical adsorption, on the activated carbon.

[0051] Acidic odorants such as sulfur dioxide are believed to be removed by activated carbon through physical adsorption, and activated carbon with developed pores tends to be suitable. Furthermore, it is known that when an adsorbent contains an alkali metal or alkaline earth metal, the physical adsorption performance is improved by a catalytic reaction. Therefore, gases can be adsorbed more efficiently by using an adsorbent containing an alkali metal salt or an alkali metal acid salt. Examples of alkali metals include sodium and potassium, and examples of alkaline earth metals include magnesium and calcium.

[0052] The ignition residue refers to the amount of metal contained in activated carbon, and can be measured by igniting activated carbon in an electric furnace and determining the residue. This measurement can be performed, for example, by the method described in JIS K 1474 "Ignition residue."

[0053] In the present invention, the ignition residue of the activated carbon is in the range of 0.1 to 7.0%, preferably 0.1 to 5.0%. It is also possible to reduce the ignition residue, i.e., the amount of metal, by washing the activated carbon with acid.

[0054] Bulk density (packing density) is the value obtained by packing powder into a container of a certain volume in a certain way and dividing the mass of the powder by the volume, including the voids between the particles. Packing density varies depending on the pore characteristics of the activated carbon; if there are few micropores, the mass of activated carbon contained per certain volume becomes heavier, so the packing density value tends to be higher. On the other hand, if there are many mesopores, the mass of activated carbon contained per certain volume becomes lighter, so the packing density value tends to be lower.

[0055] Furthermore, if the packing density is large, when the composite gas adsorbent is packed into a filter in mass terms, the packing amount of the composite gas adsorbent will be small, which may result in a decrease in performance. On the other hand, if the packing density is small, the packing amount of the composite gas adsorbent will increase, but the pressure loss during air flow through the filter may increase. Therefore, it is preferable that the packing density be within a certain range.

[0056] The packing density may be measured without drying the adsorbent (details will be described later).

[0057] In the present invention, the packing density of the activated carbon is set to a range of 0.710 g / mL or less, preferably 0.497 to 0.705 g / mL.

[0058] The raw material for activated carbon is not particularly limited, and examples thereof include plant-based materials (e.g., plant-derived materials such as wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp manufacturing by-products, lignin, and blackstrap molasses), mineral-based materials (e.g., mineral-derived materials such as peat, lignite, brown coal, bituminous coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, and petroleum pitch), synthetic resin-based materials (e.g., synthetic resin-derived materials such as phenolic resin, polyvinylidene chloride, and acrylic resin), and natural fiber-based materials (e.g., natural fiber-derived materials such as cellulose and recycled fiber such as rayon).

[0059] Among these activated carbon raw materials, plant-based materials are preferred because they have a large number of micropores, which results in excellent adsorption performance. Among these plant-based materials, fruit shells such as coconut shells are preferred as the raw material for activated carbon because they can exhibit adsorption performance more efficiently. In this embodiment, a case where coconut shells, a plant-based material, are used as the raw material for activated carbon will be described.

[0060] Activated carbon can be obtained by carbonizing or infusibilizing the above-mentioned raw materials as needed, followed by an activation treatment. The carbonization method, infusibilization method, and activation method are not particularly limited, and known techniques can be applied. For example, activation can be performed by gas activation or chemical activation. The gas activation method is a method in which the carbon raw material (or its carbonized or infusibilized product) is heat-treated in an activation gas (water vapor, carbon dioxide, etc.) at about 500 to 1000°C. The chemical activation method is a method in which the carbon raw material (or its carbonized or infusibilized product) is mixed with an activator (phosphoric acid, zinc chloride, potassium hydroxide, sodium hydroxide, etc.) and heat-treated at about 300 to 800°C.

[0061] The shape of the activated carbon is not particularly limited, and can be, for example, particulate, fibrous (thread, woven cloth, felt), block, powder, etc., and can be appropriately selected depending on the specific usage. Taking into consideration high adsorption performance per unit volume and ease of filling into a filter, the shape is preferably particulate. The size of the activated carbon is not particularly limited, and the particle size, etc. can be adjusted appropriately depending on the specific usage.

[0062] Commercially available activated carbon can also be used.

[0063] (2-Imidazolidinone) It is known that aldehydes form aldehyde-amine bonds such as Schiff bases with amine compounds. Therefore, when activated carbon is loaded with an amine compound, the aldehyde-based odorous substances, which are the cause of unpleasant odors, can be efficiently adsorbed onto the activated carbon through chemical bonds as the bond reaction occurs.

[0064] In the present invention, 2-imidazolidinone (ethylene urea) is used as the amine compound in view of operability and safety.

[0065] In this embodiment, the amount of 2-imidazolidinone supported is 3 to 30% by mass relative to the mass of activated carbon. By setting the supported amount within this range, odorous substances that can be adsorbed by chemical adsorption can be efficiently adsorbed.

[0066] If the supported amount is less than 3% by mass, the amount is too small to exhibit sufficient removal performance against aldehyde-based odorous substances, so the lower limit of the supported amount should be 3% by mass or more, more preferably 4% by mass or more, and even more preferably 5% by mass or more.

[0067] If the loading amount exceeds 30 mass%, the loading amount will be excessive, blocking pores that are effective for adsorbing volatile organic compounds, making it impossible to achieve sufficient removal performance for complex gases, particularly volatile organic compounds. Therefore, the upper limit of the loading amount should be 30 mass% or less, more preferably 25 mass% or more but less than 30 mass%, and even more preferably 20 mass% or more but less than 25 mass%.

[0068] (phosphoric acid) Phosphoric acid has excellent adsorption performance for basic odorants such as ammonia. Phosphoric acid alone does not have the adsorption performance for aldehyde odorants, but by supporting phosphoric acid together with 2-imidazolidinone on activated carbon, the adsorption rate of aldehyde odorants can be improved.

[0069] Commercially available phosphoric acid can be used.

[0070] In this embodiment, the amount of phosphoric acid supported is 3 to 30% by mass relative to the mass of activated carbon. By setting the loading amount within this range, odorous substances that can be adsorbed by chemical adsorption, particularly basic odorous substances, can be adsorbed efficiently.

[0071] If the supported amount is less than 3% by mass, the supported amount is too small to exhibit sufficient removal performance against basic odorous substances, so the lower limit of the supported amount should be 3% by mass or more, more preferably 4% by mass or more, and even more preferably 5% by mass or more.

[0072] If the loading amount exceeds 30 mass%, the loading amount will be excessive, blocking pores that are effective for adsorbing volatile organic compounds, making it impossible to achieve sufficient removal performance for complex gases, particularly volatile organic compounds. Therefore, the upper limit of the loading amount should be 30 mass% or less, more preferably 25 mass% or more but less than 30 mass%, and even more preferably 20 mass% or more but less than 25 mass%.

[0073] The mass ratio of phosphoric acid to 2-imidazolidinone is preferably 0.5 or more.

[0074] If the mass ratio is 0.5 or more, the adsorption performance of sulfur dioxide is particularly excellent.

[0075] The mass ratio is preferably 10.0 or less, that is, the mass ratio is preferably 0.5 to 10.0, more preferably 1.0 to 7.0, and even more preferably 1.0 to 5.0.

[0076] If the mass ratio is less than 0.5 (excessive 2-imidazolidinone and insufficient phosphoric acid), the phosphoric acid may be deactivated, resulting in a decrease in the adsorption performance for basic odorous substances (such as ammonia). On the other hand, if the mass ratio is greater than 10.0 (less 2-imidazolidinone and more phosphoric acid), the 2-imidazolidinone may be deactivated, resulting in a decrease in the adsorption performance for aldehyde odorous substances (formaldehyde, acetaldehyde, etc.).

[0077] (potassium compounds) As described above, it is known that when an adsorbent contains an alkali metal or alkaline earth metal, the physical adsorption performance is improved by a catalytic reaction. In this embodiment, a potassium compound is contained as the alkali metal in the activated carbon.

[0078] Potassium compounds that can be used include, but are not limited to, potassium iodide, potassium carbonate, potassium bromide, etc. In this embodiment, in consideration of operability and safety, a case where potassium iodide is used as the potassium compound will be described.

[0079] The potassium content is 0.1 mass fraction % or more relative to the composite gas adsorbent. By including the potassium content at 0.1 mass fraction % or more, the catalytic action improves the physical adsorption performance, particularly of acidic odorous substances, allowing the acidic odorous substances to be adsorbed efficiently.

[0080] If the content is less than 0.1 mass fraction, the potassium content is so small that it is difficult to exhibit catalytic action against acidic odorous substances. The lower limit of the content is preferably 0.1 mass fraction or more, more preferably 0.5 mass fraction or more, and even more preferably 1.0 mass fraction or more.

[0081] The upper limit of the content is preferably 2.4% by mass. If the upper limit exceeds 2.4% by mass, the neutralization reaction between potassium, an alkali metal, and the supported phosphoric acid is accelerated, which may reduce the reactivity with basic odorous substances such as ammonia, thereby reducing the adsorption performance.

[0082] (Acetone equilibrium adsorption performance) The amount of adsorption when the adsorption rate and desorption rate are equal and the adsorption reaches equilibrium at a constant temperature, pressure, or concentration is called the equilibrium adsorption amount. In the present invention, the equilibrium adsorption performance of acetone is specified.

[0083] That is, in the present invention, the density is 37.5 g / m in accordance with JIS K 1474 (2014). 3 The equilibrium adsorption capacity of acetone measured using acetone of 12.0 mass fraction% or more.

[0084] When the equilibrium adsorption performance of acetone satisfies this range, the physical adsorption performance of acidic odorous substances and volatile organic compounds adsorbed by physical adsorption is improved.

[0085] If the equilibrium adsorption capacity is less than 12.0 mass fraction %, sufficient removal capacity for volatile organic compounds cannot be achieved, and the lower limit is preferably 15 mass fraction % or more, more preferably 20 mass fraction % or more.

[0086] The upper limit of the equilibrium adsorption capacity for acetone is set to 40 mass fraction %, preferably 35 mass fraction %.

[0087] (pH) In the present invention, the pH of the aqueous suspension of the composite gas adsorbent is set to a value greater than 2.0, which is measured in accordance with JIS K 1474 (2014).

[0088] When the pH satisfies the above range, both basic odorous substances and acidic odorous substances can be adsorbed efficiently.

[0089] If the pH is 2.0 or less, the surface of the composite gas adsorbent will be highly acidic, and basic odorous substances that can be adsorbed by chemical adsorption with acids can be adsorbed efficiently, but on the other hand, it will be difficult to demonstrate removal performance for acidic odorous substances. The lower limit value should be 2.2 or more, more preferably 2.5 or more, and even more preferably 3.0 or more.

[0090] The upper limit of the pH is preferably 8.0, more preferably 7.2. If the upper limit exceeds 8.0, the performance against basic odorous compounds will not be sufficient, which is undesirable.

[0091] As described above, the composite gas adsorbent of the present invention comprises activated carbon, and the activated carbon supports 3 to 30 mass% of 2-imidazolidinone and 3 to 30 mass% of phosphoric acid. The composite gas adsorbent also contains potassium at a concentration of 0.1 mass% or more, and is compliant with JIS K 1474 (2014) and has a concentration of 37.5 g / m 3The composite gas adsorbent of the present invention is configured so that the equilibrium adsorption performance for acetone measured using acetone of 12.0 mass fraction % or more is achieved. As a result, the composite gas adsorbent of the present invention has particularly excellent adsorption performance for aldehyde odorous substances (acetaldehyde, etc.) and basic odorous substances (ammonia, etc.) that can be removed by chemical adsorption, as well as acidic odorous substances (sulfur dioxide, etc.) and volatile organic compounds (toluene, etc.) that can be removed by physical adsorption, and has a certain level of adsorption capacity and adsorption speed, making it possible to quickly remove composite gases containing two or more of these substances in a balanced manner.

[0092] (Method of manufacturing composite gas adsorbent) The method for producing a composite gas adsorbent of the present invention includes a preparation step A of preparing an aqueous solution by dissolving powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and powdered or particulate potassium compound in water, and a support step B of contacting the aqueous solution with activated carbon to support the aqueous solution on the activated carbon (FIG. 1). After the support step B, a drying treatment or the like may be performed by a known method.

[0093] In the preparation step A, an aqueous solution is prepared by dissolving powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and a powdered or particulate potassium compound in water. Alternatively, in the preparation step A, aqueous solutions may be individually prepared by dissolving one or more of powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and powdered or particulate potassium compound in water.

[0094] The total amount of 2-imidazolidinone, phosphoric acid, and potassium compound used in the preparation step A is preferably 60% by mass or less relative to the activated carbon, and the total amount of the aqueous solution prepared is preferably 100% by mass or less relative to the activated carbon.

[0095] The contact in the supporting step B is not particularly limited as long as it is an embodiment that allows the aqueous solution and the activated carbon to come into contact with each other, and can be, for example, an embodiment in which the aqueous solution is sprayed onto the activated carbon, an embodiment in which the aqueous solution is sprinkled onto the activated carbon, or an embodiment in which the activated carbon is immersed in the aqueous solution.

[0096] In this case, the following methods can be used to bring 2-imidazolidinone, phosphoric acid, and a potassium compound into contact with activated carbon.

[0097] (a) An aqueous solution containing 2-imidazolidinone, phosphoric acid and a potassium compound is sprayed and / or sprinkled onto activated carbon. (b) Immersing activated carbon in an aqueous solution containing 2-imidazolidinone, phosphoric acid, and a potassium compound. (c) A 2-imidazolidinone-treated product obtained by spraying and / or scattering an aqueous solution containing 2-imidazolidinone onto activated carbon or by immersing activated carbon in an aqueous solution containing 2-imidazolidinone is mixed with a phosphoric acid and potassium compound-treated product obtained by spraying and / or scattering an aqueous solution containing phosphoric acid and potassium compounds onto activated carbon or by immersing activated carbon in an aqueous solution containing phosphoric acid and potassium compounds.

[0098] By the above-mentioned loading step B, 2-imidazolidinone, phosphoric acid, and a potassium compound can be loaded evenly on the entire activated carbon.

[0099] The temperature of the aqueous solution containing 2-imidazolidinone is preferably 15 to 30° C., the temperature of the aqueous solution containing phosphoric acid is preferably 15 to 30° C., and the temperature of the aqueous solution containing a potassium compound is preferably 15 to 30° C. The supporting time is not particularly limited, but is preferably within 1 hour.

[0100] According to the method for producing a composite gas adsorbent of the present invention, it is possible to produce a composite gas adsorbent that has particularly excellent adsorption performance for a composite gas containing aldehyde odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds, meets a certain level of adsorption capacity and adsorption speed, and is capable of quickly and in a balanced manner removing a composite gas containing two or more of these substances.

[0101] (Method for removing complex gases) The complex gas removal method of the present invention uses the above-mentioned complex gas adsorbent to remove any one or more odorous substances from an indoor environment, including aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds.

[0102] Specifically, the composite gas adsorbent of the present invention is brought into contact with an indoor atmosphere containing any one or more of the above odorous substances, thereby allowing the composite gas adsorbent to come into contact with the odorous substances, thereby enabling the composite gas adsorbent to efficiently adsorb and remove any one or more of the above odorous substances.

[0103] (Application to industrial products) The composite gas adsorbent of the present invention can be used by being incorporated into industrial products.

[0104] The industrial products in question refer to conventionally widely known industrial products and industrial raw materials, including, but not limited to, paints, adhesives, inks, sealants, paper products, binders, resin emulsions, pulp, wood materials, wood products, plastic products, films, wallpaper, building materials (gypsum board, interior materials, ceiling materials, flooring materials, etc.), textile products, and filters (especially deodorizing filters for indoor air purifiers and cabin air filters).

[0105] When a filter (particularly a deodorizing filter) is used as an industrial product, a known structure can be adopted.

[0106] Furthermore, composite materials of these materials are also included in industrial products. Examples of composite materials include, but are not limited to, composite materials of wood materials and plastics.

[0107] By bringing an industrial product such as the deodorizing filter for the indoor air purifier described above, which contains the composite gas adsorbent of the present invention, into contact with, for example, multiple types of odorous substances contained in an indoor environment (aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds), the composite gas adsorbent comes into contact with the odorous substances, and the odorous substances can be efficiently adsorbed and removed.

Example

[0108] The manufacturing method of the composite gas adsorbent of the present invention will be described below.

[0109] [Examples 1-11 and Comparative Examples 1-7 of the Present Invention] For the activated carbon, coconut shells (purchased as known coconut shells collected around Southeast Asia) were used as raw materials. After carbonizing the raw materials by a conventional method, an activation treatment was performed. The activation treatment was carried out by a gas activation method. In the gas activation method, the raw materials were heat-treated at 900 °C in an activation gas (steam). In this example, activated carbon with a particle size range of 0.250 mm to 0.500 mm was used.

[0110] An aqueous solution was prepared by dissolving powdery 2-imidazolidinone, liquid phosphoric acid (concentration 85%), and particulate potassium iodide in water so as to have the supported amounts and contents shown in Table 1 (Preparation Step A). While maintaining the temperature of the aqueous solution at room temperature, it was brought into contact with 100 g of the activated carbon that had been subjected to the above treatment for 15 minutes (Supporting Step B).

[0111] <CADR Measurement Method> 6 mL of the composite gas adsorbent of the present invention was set in a 6 cm × 6 cm filter, and after setting it on the exhaust fan in a laboratory (1 m 3 ), gas was injected into the laboratory so that the concentrations of acetaldehyde, ammonia, sulfur dioxide, and toluene in the laboratory became 10 ppm each, and the exhaust fan was operated. Using an FT-IR gas analyzer (MATRIX MG5: manufactured by Bruker Japan Co., Ltd.), the concentration of each gas in the laboratory was measured every 2 minutes for 60 minutes, and from the relationship between the elapsed time and the concentration of the gas in the air, the clean air supply rate (CADR) (m 3 / h) of each gas was calculated by the following method.

[0112] <CADR Calculation Method> 1) Calculate the logarithm Ln(Ct / C0) from the initial concentration (C0) and the concentration (Ct) at each time. 2) Calculate the slope K from the logarithm Ln(Ct / C0) and the time. 3) Multiply the slope K by the test space (30 m 3 ), and calculate the CADR (m 3 / H). Regarding the method for calculating the slope K, it is distinguished and performed by the following two methods according to the value of C / C0. · When C / C0 < 0.1, calculate at the point until it falls below 0.1 · When C / C0 ≥ 0.1, calculate at all points up to 60 minutes

[0113] <Potassium content measurement method> For the test solution adjusted in accordance with "7.13.4 Inductively coupled plasma optical emission spectrometry (ICP optical emission spectrometry)" of JIS K 1474 (2014), using a multi-ICP optical emission spectrometer SPECTRO ARCOS (registered trademark) (FHX3X: manufactured by Hitachi High-Tech Science Corporation), or Agilent 5900 ICP-OES (manufactured by Agilent Technologies, Inc.), the potassium content was measured by the SOP (side-on plasma) photometric method. The analysis software used was Smart Analyzer Vison (manufactured by SPECTRO), the analysis software was SmartAnalyzer Developer (manufactured by SPECTRO), and ICP Expert (manufactured by Agilent Technologies, Inc.) to quantify the potassium content in the composite gas adsorbent.

[0114] <Acetone adsorption performance measurement method> In accordance with JIS K 1474 (2014), the equilibrium adsorption performance of acetone was measured using acetone with a concentration of 37.5 g / m 3 .

[0115] <pH measurement method> In accordance with JIS K 1474 (2014), the pH of the water suspension of the composite gas adsorbent was measured using a pH meter (F-51: manufactured by Horiba, Ltd.).

[0116] <Packing density measurement method> For each of the present invention examples and comparative examples, 6 mL of the adsorbent was filled into a 20 mL measuring cylinder without drying while gently tapping it, and the mass per unit volume was measured using the following formula. Packing density (g / mL) = sample mass (g) / 6 mL

[0117] The results are shown in Table 1.

[0118] [Table 1]

[0119] In Examples 1 to 11 of the present invention, when the amount of 2-imidazolidinone supported is 3 to 30% by mass (3.0 to 25.0% by mass), the amount of phosphoric acid supported is 3 to 30% by mass (3.0 to 25.0% by mass), the potassium content is greater than 0.1% by mass (0.19 to 2.30), and the acetone equilibrium adsorption capacity is 12.0% by mass or more (20.4 to 34.8), the CADR value is 10 m 3 / h or more, ammonia, sulfur dioxide and toluene 210m 3 / h or more.

[0120] The specific CADR value is 13 to 75 m for acetaldehyde. 3 / h, ammonia 225-326m 3 / h, sulfur dioxide 215-371m 3 / h, toluene 232-367m 3 / h.

[0121] In Inventive Examples 1 to 8, 10, and 11, the mass ratio of supported phosphoric acid to 2-imidazolidinone was 0.5 or more (0.6 to 5.0), and in Inventive Examples 1 to 11, the pH was 2.0 or more (2.1 to 7.2).

[0122] In Example 9 of the present invention, the loading mass ratio was 0.2, and the CADR value of sulfur dioxide at this time was slightly lower than the CADR values ​​of the other examples of the present invention (215 m 3 / h), so the loading mass ratio is preferably greater than 0.2, specifically 0.5 or greater.

[0123] In Inventive Examples 1 to 11, the packing density was 0.497 to 0.705 g / mL.

[0124] On the other hand, in Comparative Example 1, when the amount of 2-imidazolidinone supported was less than 3 mass% (1.0), the CADR value of acetaldehyde was 8m 3 / h, and the CADR value of the above-mentioned example of the present invention (13 to 75 m 3 / h).

[0125] In Comparative Example 2, when the amount of 2-imidazolidinone supported was 30 mass% or more (35.0), the CADR values ​​of sulfur dioxide and toluene were 66 and 39 m, respectively. 3 / h, and the CADR value of the above-mentioned example of the present invention (sulfur dioxide: 215 to 371 m 3 / h, toluene: 232-359m 3 / h) In Comparative Example 2, the acetone equilibrium adsorption capacity was 10.3.

[0126] In Comparative Example 3, when the amount of phosphoric acid supported was less than 3 mass% (1.0), the CADR value of ammonia was 192 m 3 / h, and the CADR value of the above-mentioned example of the present invention (225 to 306 m 3 / h).

[0127] In Comparative Example 4, when the amount of phosphoric acid supported was 30 mass% or more (35.0), the CADR values ​​of sulfur dioxide and toluene were 173,206 m 3 / h, and the CADR value of the above-mentioned example of the present invention (sulfur dioxide: 215 to 371 m 3 / h, toluene: 232-359m 3 / h).

[0128] In Comparative Example 5, when the potassium content was 0.06 mass fraction%, the CADR value of sulfur dioxide was 174 m 3 / h, and the CADR value of the above-mentioned example of the present invention (215 to 371 m 3 / h). This indicates that a low potassium content does not improve the sulfur dioxide adsorption efficiency. Therefore, it was found that in order to achieve sulfur dioxide adsorption performance, the potassium content must be greater than 0.06 mass fraction % (approximately 0.1 mass fraction % or more).

[0129] In Comparative Example 6, the amounts of 2-imidazolidinone and phosphoric acid supported were 3 to 30 mass % (15.0 for each) relative to the activated carbon, but the potassium content was 2.46 mass fraction %, and the acetone equilibrium adsorption performance was 9.4.

[0130] In Comparative Example 6, when the potassium content was 2.46 mass fraction%, the CADR value of sulfur dioxide was 124 m 3 / h, and the CADR value of the above-mentioned example of the present invention (215 to 371 m 3 / h). This indicates that a high potassium content does not improve the sulfur dioxide adsorption efficiency. Therefore, it was found that the potassium content must be less than 2.46 mass fraction% (approximately 2.40 mass fraction% or less) to achieve sulfur dioxide adsorption performance.

[0131] In Comparative Example 7, the amounts of 2-imidazolidinone and phosphoric acid supported on the activated carbon were 3 to 30% by mass (30.0 for each), but the acetone equilibrium adsorption performance was 8.8.

[0132] As described above, in Comparative Examples 2 and 6 and 7, when the acetone equilibrium adsorption capacity was less than 12.0 mass fraction% (10.3, 9.4, and 8.8, respectively), the CADR values ​​for sulfur dioxide and toluene were less than the CADR values ​​of the above-mentioned invention examples (sulfur dioxide: 215 to 371 m 3 / h, toluene: 232-367m 3 / h), the CADR values ​​for sulfur dioxide and toluene in Comparative Example 2 were 66 and 39 m, respectively. 3 / h, and the CADR values ​​for sulfur dioxide and toluene in Comparative Example 6 were 124,170 m 3 / h, and the CADR values ​​for sulfur dioxide and toluene in Comparative Example 7 were 36 and 56 m, respectively. 3 Therefore, it was found that the acetone equilibrium adsorption capacity of the composite gas adsorbent must be 12.0 mass fraction % or more in order to achieve the adsorption performance for acidic odorants and volatile organic compounds adsorbed by physical adsorption.

[0133] In Comparative Examples 4 and 7, when the pH was 1.9 and 2.0, respectively, the CADR values ​​of the basic odorant (ammonia) were 288 and 226 m 3 / h) is the CADR value of the above-mentioned example of the present invention (225 to 306 m 3 On the other hand, in Comparative Examples 4 and 6, when the pH was the above values, the CADR value of the acidic odorous substance (sulfur dioxide) was 173 and 36 m / s, respectively. 3 / h) is the CADR value of the above-mentioned example of the present invention (215 to 371 m 3 / h), which indicates that the pH must be higher than 2.0 in order to adsorb both basic and acidic odorous substances in a balanced manner.

[0134] In Comparative Examples 2, 4, 6, and 7, the packing density was 0.711 g / mL or more. At this time, the CADR values ​​of the acidic odorous substance (sulfur dioxide) in these Comparative Examples (66, 173, 124, and 36 m, respectively) 3 / h) is the CADR value of the above-mentioned example of the present invention (215 to 371 m 3 / h), and the CADR values ​​of toluene in these comparative examples (39, 206, 170, and 56 m 3 / h) is the CADR value of the above-mentioned invention example (232 to 359 m 3 / h). Therefore, it was found that in order to achieve the adsorption performance for acidic odorants and volatile organic compounds adsorbed by physical adsorption, the packing density of the composite gas adsorbent must be less than 0.711 g / mL (approximately 0.710 g / mL or less).

[0135] Therefore, it was found that the composite gas adsorbent of the present invention can efficiently adsorb aldehyde odorants, basic odorants, acidic odorants, and volatile organic compounds by carrying 3 to 30% by mass of 2-imidazolidinone and 3 to 30% by mass or more of phosphoric acid relative to the activated carbon, containing potassium in an amount greater than 0.1% by mass fraction and preferably 2.40% by mass fraction or less, and having an acetone equilibrium adsorption performance of 12.0% by mass fraction or more. [Industrial Applicability]

[0136] The present invention can be used in a composite gas adsorbent that adsorbs a composite gas containing multiple odorous substances, a method for manufacturing the composite gas adsorbent, a method for removing a composite gas using the composite gas adsorbent, a deodorizing filter using the composite gas adsorbent, and an air purifier using the deodorizing filter. [Explanation of symbols]

[0137] A Preparation process B. Supporting process

Claims

1. The catalyst comprises activated carbon, the activated carbon supporting 3 to 30% by mass of 2-imidazolidinone and 3 to 30% by mass of phosphoric acid, and the catalyst contains potassium in an amount of 0.1% by mass or more; Conforming to JIS K 1474 (2014), density 37.5 g / m ３ The equilibrium adsorption capacity of acetone measured using acetone of 12.0 mass fraction% or more, A composite gas adsorbent having adsorption performance for a composite gas containing a plurality of aldehyde odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds.

2. 2. The composite gas adsorbent according to claim 1, wherein the mass ratio of said phosphoric acid to said 2-imidazolidinone is 0.5 or more.

3. 3. The composite gas adsorbent according to claim 1, wherein the pH of an aqueous suspension of the composite gas adsorbent measured in accordance with JIS K 1474 (2014) is greater than 2.

0.

4. 3. The composite gas adsorbent according to claim 1, wherein the potassium is contained in an amount of 2.40 mass % or less.

5. 3. The composite gas adsorbent according to claim 1, having a packing density of 0.710 g / mL or less.

6. A method for producing a composite gas adsorbent, comprising: a preparation step of preparing an aqueous solution by dissolving powdered or particulate 2-imidazolidinone, liquid phosphoric acid, and a powdered or particulate potassium compound in water; and a supporting step of contacting the aqueous solution with activated carbon to cause the activated carbon to support the aqueous solution.

7. 7. The method for producing a composite gas adsorbent according to claim 6, wherein the potassium compound is potassium iodide or potassium carbonate.

8. A composite gas removal method for removing any one or more odorous substances selected from the group consisting of aldehyde-based odorous substances, basic odorous substances, acidic odorous substances, and volatile organic compounds contained in an indoor environment, using the composite gas adsorbent according to claim 1 or 2.

9. A deodorizing filter for an air purifier, which uses the composite gas adsorbent according to claim 1 or 2.

10. An air purifier using the deodorizing filter according to claim 9.

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