Molded adsorbent for adsorption canister

Abstract

The present application provides a new molded adsorbent suitable for a high-performance adsorption canister. As a molded adsorbent for an adsorption canister, the molded adsorbent satisfies the following requirements. The aforementioned molded adsorbent satisfies P 0.2 / 100 of 120% or less, where P 0.2 / 100 = X ÷ Y × 100... (Formula 1). In the aforementioned Formula 1, X represents the adsorption amount of n-butane gas per 100 parts by weight of the aforementioned adsorbent material under an atmosphere of 0.2 kPa of the gas pressure of n-butane gas at 25°C, and Y represents the adsorption amount of n-butane gas per 100 parts by weight of the aforementioned adsorbent material under an atmosphere of 100 kPa of the gas pressure of n-butane gas at 25°C.

Description

Technical Field

[0001] This invention relates to molded adsorbents for adsorption tanks, and more specifically, to molded adsorbents for adsorption tanks utilizing activated carbon. Background Technology

[0002] For vehicles such as cars, motorcycles (motorized two-wheelers), and ships equipped with internal combustion engines that burn vaporized fuels such as gasoline, changes in external temperature and other factors cause pressure fluctuations within the fuel tank, resulting in the release of vaporized fuel gases from the tank. These released vaporized fuel gases are one of the contributing factors to PM2.5 and photochemical smog. To prevent their release into the atmosphere, adsorption tanks equipped with adsorption materials such as activated carbon are installed (also known as vaporized fuel suppression devices).

[0003] With increasing environmental awareness in recent years, emission restrictions on various gases have tended to be strengthened year by year. Therefore, higher adsorption performance is required for adsorption tanks. Furthermore, due to the widespread use of idling, the intake capacity of automobiles is suppressed, leading to difficulties in desorbing gasoline adsorbed in the adsorption material within the adsorption tank. Therefore, there is a need for further high-performance adsorption materials used in adsorption tanks. Activated carbon is commonly used as an adsorption material for adsorption tanks, and its shape has been proposed, including granular, pellet, or honeycomb shapes (e.g., Patent Document 1).

[0004] In addition, in recent years, from the viewpoint of improving the performance of adsorption tanks, main chambers and auxiliary chambers have been set up to house the adsorbent material in multiple chambers (for example, Patent Document 2).

[0005] Compared to the ancient powdered and granular activated carbon, activated carbon fiber (or fibrous activated carbon) is sometimes referred to as the third type of activated carbon. In a broad sense, activated carbon fiber is considered to have the following characteristics: micropores open directly on the outer surface, resulting in rapid adsorption and desorption rates. However, activated carbon fiber has not yet been practically used in adsorption tanks, and the specific properties of activated carbon fiber suitable for practical adsorption tank applications have not been fully researched and developed.

[0006] As one of the adsorption materials suitable for adsorption tanks, activated carbon fiber sheets with specified properties have been proposed (Patent Document 3).

[0007] In addition, in order to improve the mechanical strength and filling density of the molded adsorbent utilizing activated carbon fibers, an activated carbon fiber molded adsorbent comprising activated carbon fibers and alkali-resistant fibrillated cellulose fibers has been proposed (for example, Patent Document 4).

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2013-173137

[0011] Patent Document 2: Japanese Patent Application Publication No. 2019-10880

[0012] Patent Document 3: Japanese Patent No. 6568328

[0013] Patent Document 4: Japanese Patent Application Publication No. 10-5580 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] Although, as mentioned earlier, activated carbon fiber has been explored as an adsorption material for adsorption tanks, it is still under development as such. Furthermore, the appropriate adsorption material for various scenarios involving filling multiple storage chambers, such as the main chamber and auxiliary chambers, has not yet been adequately researched and developed.

[0016] In view of the above situation, one of the problems to be solved by the present invention is to provide a new form of adsorption material suitable for high-performance adsorption tanks.

[0017] Another problem to be solved by the present invention is to provide a molded adsorbent body that has improved mechanical strength despite the use of activated carbon fibers, and which performs excellently as an adsorbent material for adsorption tanks.

[0018] Methods for solving problems

[0019] The inventors of this application conducted in-depth research and discovered that by mixing activated carbon with a fibrous binder to form a molded adsorbent, a suitable adsorbent material for use as a high-performance layer in an adsorption tank can be obtained, thereby completing this invention. This invention can be understood in many ways, and as a means to solve the problem, it includes, for example, the following.

[0020] [1] Molded adsorbent, which is a molded adsorbent used in an adsorption tank.

[0021] Regarding the aforementioned molded adsorbent, P is represented by the following formula 1. 0.2 / 100 It is above 18%.

[0022] P 0.2 / 100 =X÷Y×100···· (Equation 1)

[0023] In Formula 1 above, X represents the amount of n-butane gas adsorbed per 100 parts by weight of the aforementioned shaped adsorbent in an atmosphere of 25°C and n-butane gas pressure of 0.2 kPa (unit: parts by weight).

[0024] Y represents the amount of n-butane gas adsorbed per 100 parts by weight of the aforementioned shaped adsorbent in an atmosphere of 25°C and n-butane gas pressure of 100 kPa (unit: parts by weight).

[0025] [2] The shaped adsorbent as described in [1] above, wherein the aforementioned P 0.2 / 100 It is over 21%.

[0026] [3] The shaped adsorbent as described in [1] or [2] above, wherein,

[0027] Regarding the aforementioned molded adsorbent, P is represented by the following formula 2. 100 / 50 Below 120%,

[0028] P 100 / 50 =Y÷Z×100 · · · (Equation 2)

[0029] In Formula 2 above, Z represents the amount of n-butane gas adsorbed per 100 parts by weight of the aforementioned molded adsorbent in an atmosphere of 25°C and 50 kPa pressure of n-butane gas (unit: parts by weight).

[0030] Y is the same as Y in Equation 1 above.

[0031] [4] The shaped adsorbent as described in [3] above, wherein the aforementioned P 100 / 50 It is below 115%.

[0032] [5] The shaped adsorbent as described in [1] to [5] above, wherein the specific surface area of ​​the aforementioned shaped adsorbent is 2500 m². 2 / g or less.

[0033] [6] The molded adsorbent as described in any one of [1] to [5] above, wherein the total pore volume of the molded adsorbent is 0.50 to 1.20 cm³. 3 .

[0034] [7] The molded adsorbent as described in any one of [1] to [6] above, wherein the average pore size of the molded adsorbent is 1.50 to 2.00 nm or less.

[0035] [8] The molded adsorbent as described in any one of [1] to [7] above, wherein the density of the molded adsorbent is 0.010 to 0.400 g / cm³. 3 .

[0036] [9] The molded adsorbent as described in any one of [1] to [8] above, wherein the molded adsorbent comprises activated carbon and a binder.

[0037] Regarding the aforementioned ratio of activated carbon to binder, the binder comprises 0.3 to 20 parts by weight relative to 100 parts by weight of activated carbon.

[0038]

[10] The molded adsorbent as described in any one of [1] to [9] above, wherein the aforementioned activated carbon comprises activated carbon fibers.

[0039]

[11] A molded adsorbent as described in any one of [1] to

[10] above, wherein the molded adsorbent is used in an adsorption can for use in an automobile.

[0040]

[12] An adsorption tank having the molded adsorbent described in any one of [1] to

[11] above.

[0041]

[13] The adsorption tank as described in

[12] above, wherein the aforementioned adsorption tank is an adsorption tank for automobiles.

[0042] The effects of the invention

[0043] According to one aspect of the present invention, it is possible to provide a molded adsorbent with excellent adsorption-desorption properties, suitable for high-performance adsorption tanks or high-performance layers of adsorption tanks.

[0044] In addition, according to one aspect of the present invention, a molded adsorbent body for an adsorbent tank can be provided that performs excellently as an adsorbent material for an adsorbent tank, with improved mechanical strength and less prone to shape collapse. Attached Figure Description

[0045] [ Figure 1 ] Figure 1 The diagram schematically illustrates an example of a stacked adsorbent composed of multiple sheet-shaped adsorbents and an example of the flow direction of fluid passing through the stacked adsorbent.

[0046] [ Figure 2 [Image showing an example of an adsorbent shaped like a disc.]

[0047] [ Figure 3 [Image showing an example of an adsorbent shaped into a cylindrical form.] Detailed Implementation

[0048] The following describes embodiments of the present invention. It should be noted that, unless otherwise specified, the term "AA~BB" refers to "AA or higher and BB or lower" (here, "AA" and "BB" represent arbitrary values). Furthermore, unless otherwise specified, the units of the lower and upper limits are the same as those immediately following the latter (i.e., "BB" in this case).

[0049] In the description of this invention, the terms "adsorption" and "desorption" are sometimes collectively referred to as "adsorption-desorption".

[0050] Furthermore, in the description related to this invention, the term "aperture diameter" refers to the diameter or width of the aperture, rather than the radius of the aperture, unless otherwise specified.

[0051] 1. Molded adsorbent

[0052] The molded adsorbent of the present invention can be suitably used in adsorption tanks. An adsorption tank, comprising an adsorbent material, is a device that adsorbs vaporized, distilled fuel onto the adsorbent material, suppressing its emission into the atmosphere; or, when the engine is running, desorbs the distilled fuel adsorbed onto the adsorbent material and supplies it to the engine. Adsorption tanks are generally used in machinery or devices equipped with internal combustion engines that use fuels containing highly volatile hydrocarbons, such as vehicles and ships equipped with internal combustion engines. Examples of vehicles include gasoline-powered automobiles. Examples of ships include gasoline-powered boats.

[0053] In one embodiment of the present invention, the shape of the molded adsorbent is not particularly limited; for example, a shape that can be molded and allows gas flow is suitable. Specific shapes include, for example, columnar, frustum-shaped, or polygonal shapes with circular or polygonal end faces, as well as granular and honeycomb shapes, with cylindrical and cuboid shapes being preferred. Furthermore, the disc-shaped, sheet-shaped, or plate-shaped molded adsorbent can be further formed into a stacked body composed of multiple layers.

[0054] As a preferred embodiment of the present invention, embodiments that satisfy the specified requirements for the adsorption amount ratios at each pressure shown in Formula 1 or Formula 2 below can be provided. In the description related to the present invention, for example, the ratio representing the difference in adsorption amount under two different atmospheric pressures, as shown in Formula 1 or Formula 2, is referred to as the adsorption amount ratio at each pressure (unit: %). The adsorption amount ratio at each pressure can be obtained from various combinations of pressures. In Formula 1, as an embodiment, the adsorption amount ratios at each pressure obtained using the adsorption amount under a 0.2 kPa atmosphere and the adsorption amount under a 100 kPa atmosphere are shown. In Formula 2, as an embodiment, the adsorption amount ratios at each pressure obtained using the adsorption amount under a 100 kPa atmosphere and the adsorption amount under a 50 kPa atmosphere are shown.

[0055] <The adsorption ratio at various pressures obtained from Equation 1: P 0.2 / 100 >

[0056] In a preferred embodiment of the present invention, the adsorption ratio (%) at each pressure can be used as the first indicator, as shown in Formula 1 below.

[0057] P 0.2 / 100 =X÷Y×100 · · · (Equation 1)

[0058] In Formula 1, X represents the amount of n-butane gas adsorbed by the aforementioned activated carbon per 100 parts by weight in an atmosphere of 25°C and n-butane gas pressure of 0.2 kPa (unit: parts by weight).

[0059] In addition, in Formula 1, Y represents the amount of n-butane gas adsorbed by the aforementioned activated carbon per 100 parts by weight in an atmosphere of 25°C and n-butane gas pressure of 100 kPa (unit: parts by weight).

[0060] As a preferred embodiment of the present invention, the adsorption ratio (P) at each pressure shown in Formula 1 is... 0.2 / 100 The lower limit of ) can preferably be 18% or more, more preferably 19% or more, and even more preferably 20%, 21%, 22%, 23%, 24% or 25% or more.

[0061] The adsorption ratio (P) at each pressure shown in Equation 1 0.2 / 100 The upper limit of ) can preferably be 80%, more preferably 75%, and even more preferably 70, 65 or 60%.

[0062] <The adsorption ratio at various pressures obtained from Equation 2: P 100 / 50 >

[0063] In a preferred embodiment of the present invention, the adsorption ratio (%) at each pressure can be used as a second indicator, as shown in Formula 2 below.

[0064] Equation 2 below:

[0065] P 100 / 50 =Y÷Z×100 · · · (Equation 2)

[0066] In Formula 2, Z represents the amount of n-butane gas adsorbed by the aforementioned activated carbon per 100 parts by weight in an atmosphere of 25°C and n-butane gas pressure of 50 kPa (unit: parts by weight).

[0067] Furthermore, in Formula 2, Y is the same as Y in Formula 1. That is, in Formula 2, Y represents the amount of n-butane gas adsorbed by the aforementioned activated carbon per 100 parts by weight in an atmosphere of 25°C and n-butane gas pressure of 100 kPa (unit: parts by weight).

[0068] Equation 2 shows the adsorption ratio (P) at various pressures. 100 / 50 The content can preferably be 120% or less, more preferably 119% or less, and even more preferably 118, 117, 116, 115, 114, 112, 110, 108 or 106%.

[0069] The adsorption tank is typically located between the fuel tank and the engine and external gas inlet, with gas flowing back and forth between them. Fuel vapors from the fuel tank are captured by the adsorbent material inside the adsorption tank. If the capacity of the adsorbent material is exceeded, the vaporized gas is released into the external gas environment through the external gas inlet connected to the adsorption tank. On the other hand, during engine operation, the vaporized gas is drawn from the adsorbent material into the engine due to negative pressure. In other words, the adsorbent material inside the adsorption tank repeatedly adsorbs and desorbs the vaporized gas.

[0070] For adsorption tanks with multiple adsorption chambers, it is preferable to use adsorption materials with different properties in the main chamber (first chamber) and the auxiliary chambers (second chamber and subsequent chambers). In the main chamber, it is required to capture and remove a large amount of highly concentrated distilled gases flowing in from the fuel tank, etc. That is, the adsorption capacity of the main chamber is preferably large.

[0071] On the other hand, as the secondary chamber into which the gas flows from the main chamber, it is ideal to capture any evaporated gas that was not completely captured in the main chamber. That is, the concentration of evaporated gas in the gas flowing from the main chamber to the secondary chamber is relatively low, and the adsorption material in the secondary chamber needs to have high performance in capturing this low concentration of evaporated gas. For this reason, it is even more preferable that the material not only has excellent adsorption capacity, but also facilitates gas replacement during the purging of the adsorption material in the adsorption tank.

[0072] That is, as an adsorption material for an adsorption tank, especially for adsorption materials that require the capture of low concentrations of distilled gases, it is more preferable to have not only excellent adsorption capacity but also the ability to recover adsorption capacity to the point of complete desorption. Thus, higher performance adsorption materials are required, especially for the auxiliary chamber.

[0073] The inventors of this application discovered that: the adsorption ratio (P) at each pressure shown in Formula 1 0.2 / 100 Adsorbent materials with a value above the specified threshold can exhibit the high performance described above. The index (P) in Formula 1... 0.2 / 100 At higher pressures, it exhibits a high capacity for adsorbing distilled gases even under low-pressure atmospheres, i.e., low-concentration atmospheres. This high adsorption performance at low concentrations is suitable for adsorbent materials used in high-performance adsorption layer applications in adsorption tanks.

[0074] Furthermore, the inventors of this application discovered that: the adsorption ratio (P) at each pressure shown in Formula 2 100 / 50 Adsorbent materials with values ​​below the specified values ​​can exhibit the high performance described above.

[0075] The adsorption ratio at each pressure can be determined for various gas pressures. The adsorption ratio at each pressure obtained by Equation 2 is an index that expresses the difference in adsorption amount between the actual maximum gas pressure atmosphere and half of that gas pressure atmosphere (i.e., an atmosphere with approximately 50% gas concentration).

[0076] The adsorption ratio (P) at various pressures is obtained from Equation 2. 100 / 50 A concentration dependence of 120% or less indicates that the adsorption capacity does not change significantly regardless of the concentration of the evaporated gas; in other words, it exhibits low concentration dependence. Adsorption materials with such low concentration dependence are suitable as high-performance adsorption materials for adsorption tanks where it is required to capture evaporated gases even at low concentrations.

[0077] As an embodiment of the molded adsorbent of the present invention, from the viewpoint of obtaining the preferred adsorption ratios at each pressure as described above, activated carbon capable of fine pore adjustment is preferred. Among activated carbons, activated carbon fibers are more preferred from the viewpoint of readily obtaining adsorbent materials with low concentration dependence.

[0078] As an embodiment of the molded adsorbent of the present invention, a more preferred embodiment may be obtained by further satisfying at least one or any two or more of the conditions specified below.

[0079] Specific surface area

[0080] The lower limit of the specific surface area of ​​the molded adsorbent that can be used in this invention is preferably 100 m². 2 / g or more, preferably 200m 2 / g or more, more preferably 300, 500, 700, 900, 1000, 1100, or 1200 mg. 2 / g or more.

[0081] The upper limit of the specific surface area of ​​the activated carbon used in this invention can be approximately 2500, 2400, 2300, 2200, or 2100 m². 2 / g or less.

[0082] By setting the specific surface area within the range described above, it is possible to form a molded adsorbent with superior adsorption-desorption performance for vaporized fuel gases. For example, a molded adsorbent having such a specific surface area may preferably be in the form of activated carbon fibers.

[0083] The lower limit of the total micropore volume of the molded adsorbent used in this invention is preferably 0.50 cm³. 3 / g or more, preferably 0.55cm 3 / g or more, more preferably 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, or 0.90cm 3 / g or more.

[0084] The upper limit of the total micropore volume of the molded adsorbent used in this invention is preferably 1.20 cm³.3 / g or less, more preferably 1.15cm 3 / g or less, more preferably 1.10, 1.05, 1.03, or 1.00cm 3 / g or less.

[0085] By setting the total pore volume within the range described above, it is possible to form a molded adsorbent with superior adsorption-desorption performance for distilled fuel gases. For example, a morphology including activated carbon fibers is preferably used as a molded adsorbent having such a total pore volume.

[0086] <Average pore size (average pore diameter)>

[0087] The lower limit of the average pore size of the molded adsorbent that can be used in this invention is preferably 1.50 nm or more, more preferably 1.60 nm or more, and even more preferably 1.70 nm or more.

[0088] The upper limit of the average pore size of the molded adsorbent used in this invention can be arbitrary, preferably below 2.50 nm, more preferably below 2.20 nm, and even more preferably below 2.00 or 1.90 nm.

[0089] By setting the average pore size within the range described above, it is possible to form a molded adsorbent with superior adsorption-desorption performance for distilled fuel gases. For example, a morphology including activated carbon fibers is preferably used as a molded adsorbent having such an average pore size.

[0090] <Ultra-micropore volume: V 0.7 >

[0091] In this invention, the term "micropore" refers to a pore with a diameter of less than 0.7 nm.

[0092] The lower limit of the micropore volume of the molded adsorbent used in this invention is preferably 0.05 cm³. 3 / g or more, more preferably 0.10cm 3 / g or more, more preferably 0.12 or 0.14cm 3 / g or more.

[0093] The upper limit of the micropore volume of the molded adsorbent used in this invention is preferably 0.30 cm³. 3 / g or less, more preferably 0.29cm 3 Below / g, more preferably 0.26, 0.24, 0.22, or 0.20cm 3 / g or less.

[0094] By setting the micropore volume within the aforementioned range, it is possible to form a molded adsorbent with superior adsorption-desorption performance for distilled fuel gases. For example, a morphology including activated carbon fibers is preferably used as a molded adsorbent having such a micropore volume.

[0095] <Micropore volume: V 2.0 >

[0096] In this invention, the term "micropore" refers to a pore with a diameter of less than 2.0 nm.

[0097] The lower limit of the micropore volume of the molded adsorbent used in this invention is preferably 0.50 cm³. 3 / g or more, preferably 0.60cm 3 / g or more, more preferably 0.65 or 0.70 cm 3 / g or more.

[0098] The upper limit of the micropore volume of the molded adsorbent used in this invention is preferably 1.00 cm³. 3 / g or less, more preferably 0.90cm 3 Below / g, further preferably 0.80cm 3 / g or less.

[0099] By setting the micropore volume within the aforementioned range, it is possible to form a shaped adsorbent with superior adsorption-desorption performance for distilled fuel gases. Activated carbon with such an ultra-micropore volume is preferably, for example, in the form of activated carbon fibers.

[0100] <Volume of pores with a diameter greater than 0.7 nm and less than 2.0 nm: V 0.7-2.0 >

[0101] The pore volume V of pores with a diameter greater than 0.7 nm and less than 2.0 nm. 0.7-2.0 The values ​​of the ultramicropore volume a and the micropore volume b can be used to calculate the value using the following formula 3.

[0102] V 0.7-2.0 =ba···(Formula 3)

[0103] In the molded adsorbent used in this invention, the pore volume V of the pores with a diameter greater than 0.7 nm and less than 2.0 nm is... 0.7-2.0 The lower limit can preferably be 0.30cm. 3 / g or more, preferably 0.36cm 3 / g or more, more preferably 0.38, 0.40 or 0.50 cm 3 / g or more.

[0104] In the molded adsorbent used in this invention, the pore volume V of the pores with a diameter greater than 0.7 nm and less than 2.0 nm is... 0.7-2.0 The upper limit can preferably be 1.00cm. 3 / g or less, more preferably 0.90cm 3 Below / g, more preferably 0.80, 0.75, 0.70, 0.65 or 0.60cm 3 / g or less.

[0105] By increasing the pore volume V 0.7-2.0 Within the aforementioned range, it is possible to form a molded adsorbent with superior adsorption-desorption performance for evaporated fuel gases. For example, a morphology including activated carbon fibers is preferably preferred as a molded adsorbent having such an ultra-microporous volume.

[0106] The ratio of the volume of ultramicropores to the total volume of micropores: R 0.7 / 2.0 >

[0107] The proportion R of the pore volume of ultramicropores with a pore size of less than 0.7 nm to the pore volume of micropores with a pore size of less than 2.0 nm. 0.7 / 2.0 The values ​​of the ultramicropore volume a and the micropore volume b can be used to calculate the value using the following formula 4.

[0108] R 0.7 / 2.0 = a / b × 100 (%) · · · (Equation 4)

[0109] In the molded adsorbents used in this invention, the ratio R of the ultramicropore volume to the micropore volume is... 0.7 / 2.0 The lower limit is preferably 15.0% or more, more preferably 18% or more, and even more preferably 19% or more.

[0110] In the molded adsorbents used in this invention, the ratio R of the ultramicropore volume to the micropore volume is... 0.7 / 2.0 The upper limit can preferably be 60% or less, more preferably 50% or less, and even more preferably 40%, 30 or 25% or less.

[0111] By the presence ratio R of this ultramicropore volume 0.7 / 2.0 Within the aforementioned range, it is possible to form a molded adsorbent with superior adsorption-desorption performance for evaporated fuel gases. For example, a morphology including activated carbon fibers is preferably preferred as a molded adsorbent having such an ultra-microporous volume.

[0112] <Weight per square meter (weight per unit area)>

[0113] In this invention, when the activated carbon used as the material for forming the adsorbent is activated carbon fiber, the preferred form of activated carbon fiber sheet is a weight per square meter within the following range.

[0114] The lower limit of the weight per square meter can preferably be 50.0 g / m². 2 The above, more preferably 60.0 g / m 2 The above is further preferably 70.0 or 80.0 g / m 2 above.

[0115] The upper limit of weight per square meter can preferably be 200g / m². 2 The following is more preferably 150g / m 2 The following are further preferred values: 120, 110, or 100 g / m³ 2 the following.

[0116] By setting the weight per square meter within the range described above, it is possible to produce a molded adsorbent with superior adsorption-desorption performance required for the adsorption tank application, within the capacity of the adsorbent material that can be housed in the adsorption tank.

[0117] <Dry density>

[0118] In a molded adsorbent according to one embodiment of the present invention, the preferred lower and upper limits of the dry density of the molded adsorbent are as follows.

[0119] The lower limit of the dry density that can be used in this invention is preferably 0.010 g / cm³. 3 The above, more preferably 0.015 g / cm³ 3 The above is further preferred to be 0.020 g / cm³. 3 0.030, 0.040, 0.050 or 0.060 g / cm³ 3 above.

[0120] The upper limit of the dry density of the activated carbon used in this invention is preferably 0.400 g / cm³. 3 The following is more preferably 0.300 g / cm³ 3 The following are further preferred values: 0.200, 0.150, 0.140, 0.130, 0.120, 0.110, or 0.100 g / cm³. 3 the following.

[0121] By setting the drying density within the aforementioned range, a molded adsorbent with superior adsorption-desorption performance per unit volume required for adsorption tank applications can be formed within the capacity of the adsorbent material that can be contained within the adsorption tank. Furthermore, by setting it above the aforementioned lower limit, a decrease in mechanical properties (e.g., strength) can be avoided even when it is formed into sheet or disc shapes. Additionally, the drying density of the molded adsorbent can be adjusted by the fiber diameter and fiber length of the carbon fiber (which is adjusted using the stirring force during carbon fiber defiberization), and by increasing or decreasing the suction force during the suction molding of the mixture with the fibrous binder or other binder, thereby suppressing pressure loss in the molded adsorbent.

[0122] <Moisture content>

[0123] The molded adsorbents used in this invention preferably have a specified moisture content. For example, the lower limit of the moisture content under conditions of 23°C and 50% relative humidity is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more.

[0124] Furthermore, the upper limit of the moisture content under the conditions of 23°C and 50% relative humidity is preferably 30% or less, more preferably 25% or 20% or 15% or less, and even more preferably 10% or 8% or less.

[0125] By setting the moisture content within the range described above under the aforementioned conditions, activated carbon that is superior for use as a molded adsorbent in automotive adsorption canisters can be produced. For example, a molded adsorbent containing activated carbon fibers is preferred as having such a moisture content.

[0126] <Fiber diameter of activated carbon fiber>

[0127] The lower limit of the fiber diameter of the activated carbon fiber that can be used in the molded adsorbent of the present invention is preferably 4.0 μm or more, more preferably 6.0 μm or more, and even more preferably 8.0, 10.0, 12.0, 14.0, 18.0, 19.0 or 20.0 μm or more.

[0128] Regarding the upper limit of the fiber diameter of the activated carbon fibers that can be used in the molded adsorbent of the present invention, from the viewpoint of suppressing pressure loss, it can be any size. However, considering the balance with adsorption and desorption performance, for example, it can be 60.0 μm or less, preferably 55.0 μm or less, more preferably 50.0, 45.0, 40.0 or 35.0 μm.

[0129] When the diameter of the activated carbon fibers used in the shaped adsorbent is within the above-mentioned range, a shaped adsorbent that can further suppress pressure loss can be formed.

[0130] <Average fiber length of activated carbon fiber>

[0131] The lower limit of the average fiber length of the activated carbon fibers that can be used in the molded adsorbent of the present invention is preferably 300 or more, more preferably 500, 600, 700, 800, 850, 900 or more, and even more preferably 950 or more.

[0132] The upper limit of the average fiber length of the activated carbon fiber of the present invention is preferably 5000 or less, more preferably 4000, 3000, 2500, 2000, or 1500 or less, and even more preferably 1200 or less.

[0133] When the average fiber length of the activated carbon fibers that can be used in the molded adsorbent is within the above-mentioned range, a molded adsorbent that can further suppress pressure loss can be formed.

[0134] <Fiber length variation coefficient of activated carbon fiber>

[0135] The lower limit of the fiber length variation coefficient of the activated carbon fiber that can be used in the molded adsorbent of the present invention is preferably 0.100 or more, more preferably 0.200, 0.300, 0.400, 0.500 or more, and even more preferably 0.600 or more.

[0136] The upper limit of the fiber length variation coefficient of the activated carbon fibers that can be used in the molded adsorbent of the present invention is preferably 2.500 or less, more preferably 2.000, 1.500, 1.000, 0.900, 0.800 or less, and even more preferably 0.700 or less.

[0137] When the fiber length variation coefficient of the activated carbon fibers that can be used in the molded adsorbent is within the above-mentioned range, a molded adsorbent that can further suppress pressure loss can be formed.

[0138] <Fineness of the precursor of activated carbon fiber>

[0139] To obtain activated carbon fibers with the aforementioned fiber diameter, the fiber diameter (as fineness) of the fiber used as the precursor for activated carbon fibers is preferably within the following range. In other words, to obtain activated carbon fibers capable of suppressing pressure loss, it is preferable to use fibers as precursors in the following manner.

[0140] The lower limit of the fiber diameter (as fineness) of the precursor fiber is preferably 4.0 dtex or more, more preferably 5.0 dtex or more, and even more preferably 8.0, 10.0, 12.0, or 15.0 dtex or more.

[0141] The upper limit of the fiber diameter (as fineness) of the precursor fiber is preferably 60.0 dtex or less, more preferably 50.0 dtex or less, and even more preferably 40.0 or 30.0 dtex or less.

[0142] <Average particle size of granular activated carbon>

[0143] The lower limit of the average particle size of the granular activated carbon that can be used in the molded adsorbent of the present invention is preferably 100 or more, more preferably 150, 200, 250, 300, 350, 400 or more, and even more preferably 450 or more.

[0144] The upper limit of the average particle size of the granular activated carbon that can be used in the molded adsorbent of the present invention is preferably 3000 or less, more preferably 2500, 2000, 1500, 1000, 800 or less, and even more preferably 600 or less.

[0145] When the average particle size of the granular activated carbon used in the shaped adsorbent is within the above-mentioned range, a shaped adsorbent that can further suppress pressure loss can be formed.

[0146] <Particle size variation coefficient of granular activated carbon>

[0147] The lower limit of the particle size variation coefficient of the granular activated carbon that can be used in the molded adsorbent of the present invention is preferably 0.01 or more, more preferably 0.025, 0.050, 0.075, 0.100, 0.125, 0.150 or more, and even more preferably 0.175 or more.

[0148] The upper limit of the particle size variation coefficient of the granular activated carbon that can be used in the molded adsorbent of the present invention is preferably 2.500 or less, more preferably 2.000, 1.500, 1.000, 0.800, 0.600, 0.500, 0.400, 0.300 or less, and even more preferably 0.200 or less.

[0149] When the particle size variation coefficient of the granular activated carbon used in the shaped adsorbent is within the above-mentioned range, a shaped adsorbent that can further suppress pressure loss can be formed.

[0150] <n-Butane Adsorption and Desorption Performance>

[0151] In several embodiments of the present invention, the molded adsorbent preferably has a specified n-butane adsorption-desorption performance as the adsorbent material. The n-butane adsorption-desorption performance is an indicator of the adsorption-desorption performance of distilled gases; therefore, a molded adsorbent with excellent n-butane adsorption-desorption performance is suitable for automotive adsorption canister applications. Regarding the n-butane adsorption-desorption performance, the effective adsorption rate of n-butane per unit molded adsorbent can be expressed as follows: after sufficient absorption and penetration of n-butane, under specified desorption conditions, the amount adsorbed after detachment from the adsorbent material and repeated adsorption is performed.

[0152] As a preferred embodiment of the molded adsorbent of the present invention, the effective adsorption-desorption rate of n-butane determined by the measurement method shown in the following examples is preferably 6.00 wt% or more, more preferably 6.25 wt% or more, and even more preferably 6.50, 6.75 or 7.00 wt% or more.

[0153] Furthermore, as a preferred method for forming the adsorbent, the effective adsorption-desorption rate of n-butane determined according to the measurement method shown in the following examples is preferably 25.0% or more, more preferably 30.0% or more, and even more preferably 40.0%, 50.0%, 60.0%, 70.0% or 75.0% or more.

[0154] As a molded adsorbent with such n-butane adsorption properties, a form including activated carbon fibers is preferred, for example.

[0155] <0ppm duration>

[0156] Furthermore, as a preferred embodiment of the adsorption-molded body of the present invention, the 0ppm maintenance time determined by the measurement method shown in the following examples is preferably 15 minutes or 30 minutes or more, more preferably 40 minutes or more, and even more preferably 50 minutes, 55 minutes, 60 minutes, 65 minutes, 68 minutes, 69 minutes or 70 minutes or more.

[0157] A longer 0 ppm retention time means a longer period before the adsorbent material begins to release the adsorbed substance. Therefore, 0 ppm retention time is an indicator of the strength of the adsorption force.

[0158] As one embodiment of the present invention, there is a molded adsorbent comprising activated carbon and a binder. By molding incorporating not only activated carbon but also a binder, a molded body with improved mechanical strength and less prone to shape collapse can be obtained.

[0159] The activated carbon used in this invention only needs to meet the various characteristics detailed below, and its form is not particularly limited. Examples of activated carbon include powdered activated carbon, granular activated carbon, and activated carbon fibers. The activated carbon mixed in the molded adsorbent can be used alone or in combination with two or more types. Furthermore, when using multiple types of activated carbon, their proportions can be appropriately varied. For example, a mixture of 5 to 100 parts by weight of activated carbon fibers and 0 to 95 parts by weight of powdered activated carbon can be used as the activated carbon.

[0160] In one embodiment of the present invention, a binder is used as a component constituting the molded adsorbent. Preferably, the binder is one that does not close the pores of the activated carbon fibers and activated carbon. Examples of materials include, for example, aqueous solutions of polyvinyl alcohol. Furthermore, fibrous binders are also preferred examples of binders. Polyvinyl alcohol-based fibrous binders are an example of a wet-heat bonding type. Additionally, composite fibers such as core-sheath fibers, parallel fibers, and radially split fibers can also be used. Specifically, combinations of polypropylene (core) and polyethylene (sheath), polypropylene (core) and ethylene vinyl alcohol (sheath), high-melting-point polyester (core) and low-melting-point polyester (sheath), and high-melting-point polyester (core) and polyethylene (sheath) are examples. Furthermore, fibers composed solely of polyethylene and polypropylene can be used as a fully melt-bonded type. Additionally, fibrillated fibrous binders can also be used. There are no particular limitations as long as fibrillation can be used to intertwine and shape the activated carbon fibers and granular activated carbon. Both synthetic and natural products can be widely used. Examples of such fibrillated fibrous binders include acrylic fibers, polyethylene fibers, polypropylene fibers, polyacrylonitrile fibers, cellulose fibers, nylon fibers, and aramid fibers.

[0161] Regarding the ratio of activated carbon to binder in the molded adsorbent, for example, the binder can be 0.3 to 20 parts by weight relative to 100 parts by weight of activated carbon. The lower limit for the binder is preferably 0.5 parts by weight, 0.8 parts by weight, 1.0 parts by weight, 2.0 parts by weight, or 3.0 parts by weight. The upper limit for the binder is preferably 18 parts by weight, 15 parts by weight, or 10 parts by weight. By setting such a ratio, it is possible to prepare the molded adsorbent while simultaneously achieving both mechanical strength and adsorption-desorption performance. To further improve mechanical strength, the amount of binder can be increased; conversely, if adsorption-desorption performance is of greater importance, the amount of binder can be set lower.

[0162] By using the binder described above in the specified proportions, the pores of the activated carbon fibers can be kept closed, thus preventing a decrease in adsorption-desorption performance, pressure loss, and other properties. This maintains the excellent properties of the activated carbon fibers, resulting in a molded adsorbent with these superior properties.

[0163] Provided that the effects of the present invention are not rendered ineffective, the molded adsorbent as an embodiment of the present invention may contain other components besides activated carbon and binder.

[0164] 2. Shape of the adsorbent

[0165] The shape of the molded adsorbent of the present invention is not particularly limited. For example, it can be disc-shaped, cylindrical, tubular, sheet-shaped, plate-shaped, granular, honeycomb-shaped, etc. In addition, it can be a laminate obtained by further stacking multiple disc-shaped, sheet-shaped, or plate-shaped molded adsorbents. Figures 1-3 Several embodiments are shown. It should be noted that the dimensions such as length and thickness are schematically presented in the accompanying drawings for ease of understanding of the invention, and are not limited thereto.

[0166] Figure 1 The stacked absorbent 1 shown is a stack formed by stacking four shaped absorbent sheets 10. The sheet-shaped absorbent 10 is formed by stacking the main surfaces 10a of the sheets together.

[0167] The manner in which the stacked adsorbent 1 is housed within the adsorption tank is arbitrary. As a preferred embodiment, it is preferable that the main surface 10a of the sheet-like molded adsorbent is not orthogonal to the flow direction of the fluid F, such as the evaporated gas. More preferably, it is arranged as follows: Figure 1 As shown, the main surface a can be arranged approximately parallel to the flow direction of the fluid F, such as the evaporated gas. By arranging the main surface a approximately parallel to the flow direction of the fluid F, the side end faces 10b of the multiple sheet-like molded adsorbents are arranged facing the flow direction of the fluid F. By arranging them in this way, pressure loss can be suppressed. Figure 1 In this case, the shorter side face 10b faces the flow direction of the fluid F, but it is not limited to this; the longer side face 10c can also face the flow direction of the fluid F.

[0168] In addition, the stacked adsorbent can be either cuboid or cubic in shape.

[0169] Figure 2 Another embodiment of the invention is shown. Figure 2 In the illustrated embodiment, the molded adsorbent is shaped into a disc. These disc-shaped molded adsorbents can be stacked to form a cylindrical shape.

[0170] Figure 3 Another embodiment of the invention is shown. Figure 3 In the embodiment shown, the molded adsorbent is integrally molded into a cylindrical shape.

[0171] Thus, the adsorbent laminate of the present invention can be easily processed or shaped into various shapes, making it a material with excellent disposability.

[0172] 3. Adsorption tank

[0173] The molded adsorbent of the present invention is suitable as an adsorbent material housed in an automotive adsorbent can. That is, as another embodiment, the present invention can also provide an automotive adsorbent can.

[0174] The automotive adsorption can of the present invention is equipped with a molded adsorbent as the adsorbent material. There are no particular limitations on the structure of the automotive adsorption can; a general structure can be used. For example, an automotive adsorption can with the following structure can be cited.

[0175] The adsorption tank has the following features:

[0176] case;

[0177] The adsorption material chamber houses the adsorption material within the shell.

[0178] The first opening is used to connect the adsorbent material chamber and the engine in a gas-movable manner;

[0179] The second opening is used to connect the adsorbent material chamber and the fuel tank in a gas-movable manner; and

[0180] The third opening opens at a pressure specified by the adsorption material chamber or the external gas load, and is used to connect the adsorption material chamber with the external gas in a gas-movable manner.

[0181] In the adsorption tank of the present invention, the molded adsorbent of the present invention described above can be used as the adsorbent material. As described above, the molded adsorbent of the present invention can reduce pressure loss, and therefore, even when filled without gaps, pressure loss can be suppressed compared to the case of filling with conventional activated carbon fiber sheets, etc.

[0182] The first opening, second opening, and third opening are gas inlets and outlets for gas flow. The arrangement of each opening, serving as a gas inlet and outlet, is not particularly limited. However, the third opening, serving as an inlet and outlet for external gas, is preferably positioned where gas can pass sufficiently through the adsorbent material when moving between the first opening and / or the second opening. For example, embodiments may be adopted where the first and second openings are located on the first side surface of the housing, and the third opening is located on the second side surface opposite the first side surface.

[0183] The adsorbent material chamber can be divided into multiple chambers. For example, the adsorbent material chamber can be divided into two or more regions by partitions. As partitions, perforated plates with ventilation properties can be used. Furthermore, an external second housing can be provided separately from the first housing, and the adsorbent material chamber can be added by connecting the first and second housings via a gas passage. In the case of providing multiple regions or housings as described above, as a preferred embodiment, the adsorbent material or adsorbent material chamber can be arranged such that the adsorption capacity in each region or housing unit decreases sequentially from the first or second opening (where gas flows in from the engine or fuel tank) towards the third opening.

[0184] As a specific example, a composite adsorption tank can be described, comprising a main adsorption tank (first shell) and a second adsorption tank (second shell) attached to the inlet side of the external gas compared to the main adsorption tank. In the case of providing multiple regions or shells as described above, the region or shell into which the vaporized gas initially flows from the engine or fuel tank serves as the main body (first region or first shell) with the largest housing volume, and conventionally inexpensive activated carbon is housed therein. On the other hand, the low-concentration, well-formed adsorbent with excellent adsorption-desorption performance of the present invention is housed after the relatively smaller second region or second shell. Thus, a high-performance adsorption tank can be manufactured while suppressing costs.

[0185] In the presence of multiple adsorbent chambers, the concentration of vaporized fuel gas flowing in from the front layer becomes dilute in the adsorbent chamber located further back when viewed from the engine or fuel tank (i.e., the adsorbent chamber positioned closer to the inlet / outlet of external gas). Therefore, activated carbon, with its high adsorption capacity for n-butane at a low concentration of approximately 0.2%, is suitable as an adsorbent material housed in a second region or second shell, or even further back, when viewed from the engine or fuel tank. Furthermore, when activated carbon is used in an adsorbent chamber closer to the inlet of external gas, the shaped adsorbent of the present invention exhibits a high effective adsorption / desorption capacity based on purging. Therefore, it is suitable as an adsorbent material for use in automotive adsorbent canisters, even from the perspective of reducing the leakage of vaporized fuel gas during prolonged vehicle parking.

[0186] Therefore, as a preferred embodiment of the adsorption tank, the following configuration can be cited as an example.

[0187] An adsorption tank, wherein the adsorption tank is for use in automobiles, and it has a main chamber and a secondary chamber for storing adsorbent material.

[0188] Compared to the main chamber, the secondary chamber has a smaller volume for accommodating the adsorbent material and is positioned closer to the opening that communicates with the external gas.

[0189] The adsorbent material of the present invention is housed in the sub-chamber.

[0190] In the above configuration, there can be one main chamber and one secondary chamber, or there can be two or more of each. Furthermore, if there are three or more adsorbent material chambers, the molded adsorbent of the present invention can be housed in at least one adsorbent material chamber of the secondary chamber, preferably in the secondary chamber closest to the opening communicating with the external gas.

[0191] 4. Manufacturing method of shaped adsorbent

[0192] The molded adsorbent of the present invention described above can be obtained by molding activated carbon into a predetermined shape. As the activated carbon, for example, activated carbon that satisfies the requirements shown as preferred indicators of the molded adsorbent described above (e.g., indicators represented by Formula 1, Formula 2, etc.) can be used.

[0193] As one embodiment of the molded adsorbent of the present invention described above, it can be obtained, for example, by mixing activated carbon with a fibrous binder and molding it.

[0194] When activated carbon fiber is used as activated carbon, activated carbon fiber can be manufactured, for example, by carbonizing and activating fibers with a specified fiber diameter. Carbonization and activation can be performed using conventional methods.

[0195] The following is an example of an implementation method for manufacturing activated carbon fiber sheets using precursor sheets (raw material sheets).

[0196] It should be noted that the activated carbon used in this invention is not limited to sheet form. Activated carbon fiber sheets can be manufactured using precursor sheets (raw material sheets) as shown below, or a specified activated carbon powder can be prepared.

[0197] 4-1. Preparation of raw material sheet (precursor fiber sheet)

[0198] <Types of Fibers>

[0199] Examples of fibers that constitute the raw material sheet include cellulose fibers, pitch fibers, PAN fibers, and phenolic resin fibers, with cellulose fibers being the most preferred.

[0200] <Cellulose-based fibers>

[0201] Cellulose-based fibers are fibers composed primarily of cellulose and / or its derivatives. Cellulose and cellulose derivatives can be derived from chemically synthesized substances, plants, regenerated cellulose, bacterial cellulose, etc. Preferably, cellulose-based fibers are those formed from plant-based cellulose materials obtained from trees, etc., or those composed of long fibrous regenerated cellulose materials obtained by chemically treating and dissolving plant-based cellulose materials (cotton, pulp, etc.). Furthermore, these fibers may contain components such as lignin and hemicellulose.

[0202] Examples of raw materials for cellulose-based fibers (plant-based cellulose substances, regenerated cellulose substances) include, for example, plant-based cellulose fibers such as cotton (short-fiber cotton, medium-fiber cotton, long-fiber cotton, extra-long-fiber cotton, ultra-long-fiber cotton, etc.), hemp, bamboo, grape, daphne, banana, and tunicate; regenerated cellulose fibers such as cuprammonium rayon, viscose rayon, polynosic rayon, and cellulose made from bamboo; purified cellulose fibers spun using organic solvents (N-methylmorpholine N-oxide); and acetate fibers such as diacetate and triacetate; etc. Among these, considering ease of acquisition, at least one selected from cuprammonium rayon, viscose rayon, and purified cellulose fibers is preferred.

[0203] The diameter of the individual fibers constituting the cellulose-based fibers is preferably 5–75 μm, and the density is 1.4–1.9 μm. 3 / g.

[0204] The form of cellulose-based fibers is not particularly limited. Depending on the purpose, cellulose-based fibers can be used to produce raw yarn, false-twisted yarn, dyed yarn, single yarn, folded yarn, covering yarn, etc. Furthermore, when cellulose-based fibers contain two or more raw materials, they can be made into blended yarn, mixed-twist yarn, etc. Moreover, as cellulose-based fibers, two or more of the aforementioned forms of raw materials can be used alone or in combination. Among these, from the viewpoint of combining the formability and mechanical strength of composite materials, untwisted yarn is preferred.

[0205] <Fiber Sheets>

[0206] Fiber sheets refer to materials made by processing a large amount of fibers into thin and large sheets, including woven fabrics, knitted fabrics, and non-woven fabrics.

[0207] There are no particular restrictions on the method of weaving cellulose fibers; common methods can be used. In addition, there are no particular restrictions on the fabric structure; plain weave, twill weave, and satin weave can be used.

[0208] For woven fabrics made from cellulose fibers, the gap between the warp and weft yarns of the cellulose fibers is preferably 0.1–0.8 mm, more preferably 0.2–0.6 mm, and even more preferably 0.25–0.5 mm. Furthermore, the area weight of the woven fabric made from cellulose fibers is preferably 50–500 g / m². 2 More preferably 100–400 g / m 2 .

[0209] By defining the cellulose-based fibers and the woven fabrics formed from the cellulose-based fibers as described above, it is possible to make the carbon fiber woven fabric obtained by heat-treating the woven fabric into a woven fabric with excellent strength.

[0210] There are no particular limitations on the manufacturing method of nonwoven fabrics. For example, methods such as using the aforementioned fibers cut to appropriate lengths as raw materials and obtaining fiber sheets using dry or wet methods; or methods such as electrospinning to directly obtain fiber sheets from a solution. Furthermore, after obtaining the nonwoven fabric, treatments such as resin bonding, thermal bonding, hydroentangling, and needle punching can be applied to bind the fibers together.

[0211] 4-2. Catalyst

[0212] In Embodiment 1 of the manufacturing method, the catalyst is held in the raw material sheet prepared as described above. The catalyst is held in the raw material sheet and carbonization is performed, followed by activation using water vapor, carbon dioxide, air, or the like, thereby obtaining a porous activated carbon fiber sheet. For example, phosphoric acid-based catalysts or organic sulfonic acid-based catalysts can be used as the catalyst.

[0213] <Phosphoric Acid Catalysts>

[0214] Examples of phosphoric acid catalysts include, for instance, hydroxy acids of phosphorus such as phosphoric acid, metaphosphoric acid, pyrophosphoric acid, phosphorous acid, phosphonic acid, phosphonous acid, and hypophosphonic acid; diammonium hydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, dimethylphosphonopropionamide, ammonium polyphosphate, and polyphosphazene chloride; and condensates of phosphoric acid, tetra(hydroxymethyl)phosphonium salts, or tri(1-acrylidinyl)phosphine oxide with urea, thiourea, melamine, guanine, ammonia nitrile, hydrazine, dicyandiamide, or their hydroxymethyl derivatives, with diammonium hydrogen phosphate being a preferred example. A single phosphoric acid catalyst can be used alone, or two or more can be used in combination. When using a phosphoric acid catalyst in aqueous solution, its concentration is preferably 0.05–2.0 mol / L, more preferably 0.1–1.0 mol / L.

[0215] <Organic sulfonic acid catalysts>

[0216] As organic sulfonic acids, organic compounds having one or more sulfonyl groups can be used, such as compounds with sulfonyl groups bonded to various carbon skeletons, including aliphatic and aromatic compounds. From a disposal point of view, low molecular weight organic sulfonic acid catalysts are preferred as organic sulfonic acid catalysts.

[0217] Examples of organic sulfonic acid catalysts include compounds represented by R-SO3H (where R represents a straight-chain / branched alkyl group with 1 to 20 carbon atoms, a cycloalkyl group with 3 to 20 carbon atoms, or an aryl group with 6 to 20 carbon atoms, and the alkyl, cycloalkyl, and aryl groups can each be substituted by an alkyl group, a hydroxyl group, or a halogen group). Examples of organic sulfonic acid catalysts include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, 1-hexanesulfonic acid, vinylsulfonic acid, cyclohexanesulfonic acid, p-toluenesulfonic acid, p-phenolsulfonic acid, naphthalenesulfonic acid, benzenesulfonic acid, and camphorsulfonic acid. Methanesulfonic acid is preferred. Furthermore, one type of organic sulfonic acid catalyst can be used alone, or two or more types can be used in combination.

[0218] When organic sulfonic acid is used in the form of an aqueous solution, its concentration is preferably 0.05 to 2.0 mol / L, more preferably 0.1 to 1.0 mol / L.

[0219] <Mixed Catalysts>

[0220] The aforementioned phosphoric acid catalysts and organic sulfonic acid catalysts can be mixed to form a mixed catalyst. The mixing ratio can be adjusted appropriately.

[0221] <Catalyst retention>

[0222] The catalyst is kept within the raw material sheet. Here, "keeping" refers to maintaining the state of contact between the catalyst and the raw material sheet, which can take many forms such as adhesion, adsorption, or impregnation. There are no particular limitations on the method of keeping the catalyst; examples include: impregnation in an aqueous solution containing the catalyst, sprinkling an aqueous solution containing the catalyst onto the raw material sheet, contacting with vaporized catalyst vapor, and mixing the fibers of the raw material sheet into an aqueous solution containing the catalyst for papermaking.

[0223] From the viewpoint of achieving sufficient carbonization, it is preferable to use the following method: Impregnate the raw material sheet in an aqueous solution containing the catalyst, so that the catalyst is impregnated into the fibers. The temperature during impregnation in the aqueous solution containing the catalyst is not particularly limited, but room temperature is preferred. The impregnation time is preferably 10 seconds to 120 minutes, more preferably 20 seconds to 30 minutes. Impregnation allows the fibers constituting the raw material sheet to adsorb, for example, 1 to 150% by mass, preferably 5 to 60% by mass of the catalyst. After impregnation, it is preferable to remove the raw material sheet and dry it. As a drying method, any method can be used, such as placing it at room temperature and then introducing it into a dryer. Drying is sufficient to continue until excess water evaporates and the sample weight no longer changes after removal from the aqueous solution containing the catalyst. For example, for room temperature drying, it is sufficient to place it for a drying time of 0.5 days or more. After drying until the weight hardly changes, a carbonization process is performed on the raw material sheet containing the catalyst.

[0224] 4-3. Carbonization treatment

[0225] After preparing the raw material sheet containing the catalyst, it is subjected to a carbonization treatment. The carbonization treatment for obtaining activated carbon fiber sheets can be carried out according to the conventional activated carbon carbonization method, and as a preferred embodiment, it can be carried out in the following manner.

[0226] Carbonization is typically carried out in an inert gas atmosphere. In this invention, an inert gas atmosphere refers to an oxygen-free or low-oxygen atmosphere in which carbon does not readily undergo combustion reactions for carbonization; preferably, it can be an atmosphere containing gases such as argon or nitrogen.

[0227] The raw material sheet containing the catalyst can be carbonized by heating in the gas atmosphere specified above.

[0228] The lower limit of the heating temperature is preferably above 300°C, more preferably above 350°C, and even more preferably above 400°C or above 750°C.

[0229] The upper limit of the heating temperature is preferably below 1400°C, more preferably below 1300°C, and even more preferably below 1200°C or below 1000°C.

[0230] By setting the heating temperature to this level, carbon fiber sheets that maintain their fibrous shape can be obtained. If the heating temperature is below the aforementioned lower limit, the carbon content of the carbon fiber will be below 80%, and carbonization will easily become incomplete.

[0231] The lower limit of the heating treatment time also includes the heating time, which is preferably 10 minutes or more, more preferably 11 minutes or more, even more preferably 12 minutes, 15 minutes, 20 minutes, 25 minutes or more, and more preferably 30 minutes or more.

[0232] The upper limit of the heat treatment time can be arbitrary, preferably less than 180 minutes, more preferably less than 160 minutes, and even more preferably less than 140 minutes.

[0233] By fully impregnating the catalyst in the raw material sheet and setting the heating temperature to the above-mentioned preferred temperature, and adjusting the heating treatment time, the degree of micropore formation can be adjusted, and the physical properties of the porous body, such as specific surface area, volume of various micropores, and average micropore diameter, can be adjusted.

[0234] If the heat treatment time is less than the lower limit mentioned above, carbonization is likely to become incomplete.

[0235] Furthermore, as a heat treatment, after the heat treatment described above (sometimes called primary heat treatment), a further reheat treatment can be performed in a specified gas atmosphere. That is, the carbonization treatment can be carried out in multiple stages under different conditions such as temperature. By performing primary and reheat treatments under specified conditions, it is sometimes possible to adjust the physical properties, achieve better carbonization, and subsequently activate the carbon fibers to obtain activated carbon fiber sheets with excellent adsorption and desorption properties.

[0236] 4-4. Activation treatment

[0237] As an activation treatment in this invention, for example, water vapor and carbon dioxide can be continuously supplied after the above-mentioned heat treatment and maintained at an appropriate activation temperature for a specified time to obtain activated carbon fiber sheets.

[0238] The lower limit of the activation temperature is preferably above 300°C, more preferably above 350°C, and even more preferably above 400, 500, 600, 700 or 750°C.

[0239] On the other hand, the upper limit of the activation temperature can preferably be below 1400°C, more preferably below 1300°C, and even more preferably below 1200 or 1000°C.

[0240] It should be noted that when the activation treatment is performed continuously after the heat treatment, it is preferable to adjust it to the same degree as the heat treatment temperature.

[0241] The minimum activation time is preferably more than 1 minute, and more preferably more than 5 minutes.

[0242] The upper limit of the activation time can be arbitrary, preferably less than 180 minutes, more preferably less than 160 minutes, and even more preferably less than 140 minutes, less than 100 minutes, less than 50 minutes, or less than 30 minutes.

[0243] 4-5. Making the molded body

[0244] There are no particular limitations on the processing method for the molded article containing activated carbon fibers and fibrous binder; for example, it can be obtained by preparing a mixture of the two and molding it. As one embodiment, the molded article can be produced, for example, in the following manner.

[0245] <Preparation of slurry containing activated carbon fibers and fibrous binders>

[0246] Pre-prepared activated carbon fiber sheets and fibrous binder are mixed in water, and then the mixture is defibrinated and dispersed using a mixer to obtain a slurry containing both materials. The activated carbon fiber sheets to be added to the mixer can be prepared into small pieces of appropriate size according to the mixer's specifications.

[0247] <Forming of Molded Components>

[0248] The slurry containing activated carbon fibers and fibrous binder, obtained in the above manner, is poured into a mold of the desired shape, and moisture is removed while pressing. Then it is dried to obtain a shaped adsorbent.

[0249] Example

[0250] The following examples illustrate the present invention in detail, but the technical scope of the present invention is not limited to the following examples.

[0251] Various properties and performance characteristics related to activated carbon fibers, granular activated carbon, and shaped adsorbents were measured and evaluated using the methods described below. It should be noted that the various values ​​specified in this invention can be obtained using the following measurement and evaluation methods.

[0252] Specific surface area

[0253] Approximately 30 mg of sample (activated carbon fiber sheets, granular activated carbon, or molded adsorbents) was collected, vacuum dried at 200°C for 20 hours, weighed, and measured using a high-precision gas / vapor adsorption capacity analyzer, BELSORP-maxII (MicrotracBEL Corp.). The relative pressure was 10... -8The amount of nitrogen adsorbed at the boiling point (77 K) of liquid nitrogen was determined within the range of orders of magnitude to 0.990, and an adsorption isotherm of the sample was prepared. This adsorption isotherm was analyzed using the BET method, which automatically determines the analytical relative pressure range under the conditions of Adsorption Isotherm Type I (ISO 9277), and the BET specific surface area per unit weight (unit: m²) was calculated. 2 / g), which is used as the specific surface area (unit: m²) 2 / g).

[0254] <Total fine pore volume>

[0255] Based on the isothermal adsorption curve obtained from the specific surface area term above, under a relative pressure of 0.960, the total pore volume (unit: cm³) was calculated using the single-point method. 3 / g).

[0256] <Average pore diameter (average pore size) unit: nm>

[0257] It can be calculated using Equation 5 below.

[0258] Average pore diameter = 4 × total pore volume × 10 3 ÷ Specific surface area... (Equation 5)

[0259] <Ultra-micropore volume>

[0260] Using the BELMaster analytical software accompanying the high-precision gas / vapor adsorption capacity measurement device BELSORP-maxII (MicrotracBEL Corp.), the GCMC method was employed with the analysis settings set to "Smoothing (using a moving average of one point before and after each analytical point in the pore distribution)," "Distribution Function: No-assumption," "Pore Size Definition: Solid and Fluid Def. Pore Size," and "Kernel: Slit-C-Adsorption." The isothermal adsorption curves obtained in the specific surface area term were analyzed, and the cumulative pore volume at 0.7 nm was read from the resulting pore distribution curves during adsorption as the ultramicropore volume (unit: cm). 3 / g).

[0261] <Micropore Volume>

[0262] Using the BELMaster analytical software included with the high-precision gas / vapor adsorption capacity measuring instrument BELSORP-maxII (MicrotracBEL Corp.), the GCMC method was employed with the analysis settings set to "Smoothing (using a moving average of one point before and after each analytical point in the pore distribution)," "Distribution function: No-assumption," "Pore size definition: Solid and Fluid Def. Pore Size," and "Kernel: Slit-C-Adsorption." The isothermal adsorption curves obtained in the specific surface area term were analyzed, and the cumulative pore volume at 2.0 nm was read from the resulting pore distribution curves during adsorption as the micropore volume (unit: cm). 3 / g).

[0263] <Weight per square meter of sheet>

[0264] The test sample (such as activated carbon fiber sheet) was left to stand for at least 12 hours at a temperature of 23±2℃ and a relative humidity of 50±5%. The weight per square meter of the sheet was calculated based on its weight and longitudinal and transverse dimensions (unit: g / m²). 2 ).

[0265] <Sheet Thickness>

[0266] The sample (such as activated carbon fiber sheet) was left to stand for more than 12 hours at a temperature of 23±2℃ and a relative humidity of 50±5%. The sheet thickness (unit: mm) was measured when a load of 0.3 kPa was applied using a digital miniature thickness gauge FS-60DS (Daiei Kagaku Seiki Mfg.Co.,Ltd.).

[0267] Humidity-Controlled Density of Sheets: Unit: g / cm³ 3 >

[0268] It can be calculated using the following formula 6.

[0269] Sheet density = weight of sheet per square meter ÷ sheet thickness ÷ 10 3 ...(Equation 6)

[0270] <Sheet moisture>

[0271] The sample (such as activated carbon fiber sheet) is placed in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for more than 12 hours. Then, 0.5 to 1.0 g of sample is collected and dried in a dryer at 115±5℃ for more than 3 hours. The moisture content (unit: %) is calculated based on the weight change during this period.

[0272] <Dimensional Measurement of Molded Adsorbents>

[0273] The dimensions of the molded adsorbent are determined by measuring the dimensions using vernier calipers and rulers. The dry weight of the molded adsorbent is then measured using an electronic balance.

[0274] Density of the shaped adsorbent: Unit: g / cm³ 3 >

[0275] Calculate using the following formula 7.

[0276] Density = Dry weight of the formed adsorbent ÷ Volume of the formed adsorbent ... (Equation 7)

[0277] The volume of the shaped adsorbent is calculated based on the dimensional measurement results of the shaped adsorbent.

[0278] <n-Butane Adsorption and Desorption Performance>

[0279] Referring to the American Society for Testing and Materials (ASTM) standard Standard Test Method for Determination of Butane Working Capacity of Activated Carbon (ASTM D5228-16), the concentration and flow rate of n-butane gas and the flow rate of desorption air were set separately for the test.

[0280] The shaped adsorbent was dried at 115±5℃ for more than 3 hours using a dryer, and its dried weight was measured after cooling. After measuring the mass of an empty adsorption container (a stainless steel frame container with the same cross-sectional shape as the shaped adsorbent and capable of gas flow), the shaped adsorbent was filled into the adsorption container.

[0281] Next, the test tube is placed in a flow-through apparatus. Under test temperature of 25°C, n-butane gas diluted with air to a concentration of 0.2% is flowed into the test tube at a rate of 1.0 L / min to adsorb n-butane. The test tube is then removed from the flow-through apparatus, and its mass is measured. The flow-through of the 0.2% concentration n-butane gas is repeated until a constant mass is reached, i.e., until the adsorption capacity is saturated.

[0282] The test tube was repositioned in the flow-through apparatus, and air was allowed to flow through the tube at a rate of 20.0 L / min for 12 minutes at a test temperature of 25°C to desorb the n-butane. The test tube was then removed from the flow-through apparatus and its mass was measured.

[0283] <Determination of 0ppm Duration>

[0284] The concentration changes of adsorption and desorption of n-butane were measured every 6 seconds using a portable gas detector, Cosmotector (model: XP-3160, manufacturer: New Cosmos Electric Co., Ltd.).

[0285] After repeating the first adsorption and desorption, for the concentration change of the second adsorption, the case where it is below the lower limit of quantitation (25 ppm) is set as 0 ppm, and the time that the 0 ppm is maintained from the beginning is taken as the 0 ppm maintenance time (minutes).

[0286] Repeat the adsorption and desorption operation a total of 2 times, and use the following formulas 8, 9, 10, and 11 to calculate the first adsorption amount, effective adsorption and desorption amount, effective adsorption and desorption rate, and effective adsorption and desorption rate.

[0287] <Formula 8>

[0288] First adsorption capacity = First n-butane adsorption capacity

[0289] It should be noted that the units for each value are as follows.

[0290] First n-butane adsorption amount (unit: g)

[0291] <Formula 9>

[0292] Effective adsorption / desorption capacity = (Second n-butane adsorption capacity + Second n-butane desorption capacity) ÷ 2

[0293] It should be noted that the units for each value are as follows.

[0294] Effective adsorption / desorption capacity (unit: g)

[0295] Second n-butane adsorption capacity (unit: g)

[0296] Second n-butane desorption amount (unit: g)

[0297] <Formula 10>

[0298] Effective adsorption-desorption rate = Effective adsorption-desorption amount ÷ Dry weight of the shaped adsorbent × 100. It should be noted that the units of each value are as follows.

[0299] Effective adsorption / desorption rate (unit: wt%)

[0300] Effective adsorption / desorption capacity (unit: g)

[0301] Dry weight of the shaped adsorbent (unit: g)

[0302] <Formula 11>

[0303] Effective adsorption-desorption rate = Effective adsorption-desorption amount ÷ First adsorption amount × 100

[0304] It should be noted that the units for each value are as follows.

[0305] Effective adsorption-desorption rate (unit: %)

[0306] Effective adsorption / desorption capacity (unit: g)

[0307] First adsorption amount (unit: g)

[0308] <Adsorption capacity at various pressures (unit: wt% or g / 100g)>

[0309] Approximately 100 mg of activated carbon fiber sheets, granular activated carbon, or shaped adsorbents were collected, vacuum-dried at 200 °C for 20 hours, and weighed. The adsorption capacity was measured using a high-precision gas / vapor adsorption capacity measuring device, BELSORP-maxII (Microtrack Bell). The adsorption capacity of n-butane gas at 25 °C was measured within an absolute pressure range of 0.1–105 kPa, and an n-butane adsorption isotherm (in g) was prepared for the sample. This n-butane adsorption isotherm was divided by the dried weight of the sample (in g) to prepare another n-butane adsorption isotherm (in wt%). The n-butane gas adsorption capacity at 0.2 kPa, 0.5 kPa, 5 kPa, 50 kPa, and 100 kPa was read from this adsorption isotherm. The n-butane gas adsorption capacities at 0.2 kPa, 100 kPa, and 50 kPa were designated as X, Y, and Z, respectively. The following explanation follows.

[0310] (1) X (unit: wt% or g / 100g): The amount of n-butane gas adsorbed per 100g of adsorbent material in an atmosphere of 25℃ and n-butane gas pressure of 0.2kPa (unit: g).

[0311] (2) Y (unit: wt% or g / 100g): The amount of n-butane gas adsorbed per 100g of adsorbent material in an atmosphere of 25℃ and n-butane gas pressure of 100kPa (unit: g).

[0312] (3) Z (unit: wt% or g / 100g): The amount of n-butane gas adsorbed per 100g of the adsorbent material in an atmosphere of 25℃ and n-butane gas pressure of 50kPa (unit: g).

[0313] <Adsorption capacity ratio at various pressures (unit: %)>

[0314] Based on the measured values ​​X, Y, and Z obtained in the above manner, P is calculated using Equation 1. 0.2 / 100P is calculated using Equation 2. 100 / 50 .

[0315] P 0.2 / 100 =X÷Y×100···· (Equation 1)

[0316] P 100 / 50 =Y÷Z×100··· (Equation 2)

[0317] <Example 1>

[0318] (1.1) Activated carbon fiber sheets

[0319] The weight per square meter formed from rayon fibers (17 dtex, fiber length 76 mm) is 400 g / m². 2 The needle-punched nonwoven fabric was impregnated with a 6-10% diammonium hydrogen phosphate aqueous solution. After extruding the liquid, it was dried to allow 8-10% by weight to adhere. The resulting pretreated nonwoven fabric was heated to 900°C in a nitrogen atmosphere for 40 minutes and held at that temperature for 3 minutes. Then, it was subjected to an activation treatment at this temperature in a nitrogen stream containing water vapor with a dew point of 71°C for 17 minutes to obtain activated carbon fiber sheets.

[0320] (1.2) Molded Adsorbent

[0321] Five parts by weight (0.26 g) of acrylic fiber 50TWF manufactured by Japan Exlan Co., Ltd., used as a fibrous binder, were added to a mixer along with 0.5 L of water. The mixture was de-fibriled and dispersed for 30 seconds. Then, 100 parts by weight (5.10 g) of the activated carbon fiber sheet obtained in (1.1) above and 0.5 L of water were added, and the mixture was further de-fibriled and dispersed for 10 seconds to obtain an activated carbon fiber adsorption slurry. A metal cylinder with an inner diameter of 63 mm and a height of 400 mm, which can be divided at a position 18 mm from the bottom, was placed on a funnel equipped with a perforated plate for suction dehydration. The adsorption slurry was injected into the metal cylinder, and then suction dehydration was performed from the bottom to form the slurry. The bottom 18mm of the molded body, containing a moistened material, was cut from a metal cylinder. The upper and lower sections of the metal cylinder were clamped using a perforated plate, and a 1kg weight was placed on top. The molded body was then dried at 120℃ for 4 hours while pressed to a height of 18mm. The metal cylinder was then removed, yielding a disc-shaped absorbent with an outer diameter of 62mm and a height of 18mm. Compared to activated carbon fiber sheets, the resulting molded absorbent is less prone to shape collapse.

[0322] <Example 2>

[0323] (2.1) Activated carbon fiber sheets

[0324] The same activated carbon fiber sheet as in Example 1 above.

[0325] (2.2) Molded Adsorbent

[0326] The procedure was the same as in Example 1, except that the activated carbon fiber adsorption slurry and activated carbon fiber sheets were replaced with granular activated carbon (specific surface area of ​​1660 m²). 2 A granular activated carbon adsorption slurry was obtained by measuring 60 parts by weight (3.37 g) of activated carbon fiber adsorption slurry and 40 parts by weight (2.25 g) of granular activated carbon adsorption slurry, with an average particle size of 502 μm and a standard deviation of 89 μm. The slurry was then separately taken and mixed to obtain a mixed adsorption slurry of activated carbon fiber and granular activated carbon. This adsorption slurry was dehydrated and dried using the same method as in Example 1 to obtain a disc-shaped adsorbent with an outer diameter of 62 mm and a height of 18 mm. Compared to activated carbon fiber sheets, the obtained molded adsorbent is less prone to shape collapse.

[0327] <Comparative Example 1>

[0328] (3.1) Activated carbon fiber sheets

[0329] The weight per square meter formed from rayon fibers (17 dtex, fiber length 76 mm) is 400 g / m². 2 The needle-punched nonwoven fabric was impregnated with a 6-10% diammonium hydrogen phosphate aqueous solution. After extruding the liquid, it was dried to allow 8-10% by weight to adhere. The resulting pretreated nonwoven fabric was heated to 950°C in a nitrogen atmosphere for 50 minutes and held at that temperature for 4 minutes. Then, it was subjected to an activation treatment at this temperature in a nitrogen stream containing water vapor with a dew point of 71°C for 18 minutes to obtain activated carbon fiber sheets.

[0330] (3.2) Molding Adsorbent

[0331] The shaped adsorbent was obtained using the same preparation method as in Example 1 above.

[0332] <Comparative Example 2: Granular Activated Carbon>

[0333] Granular activated carbon was removed from a commercially available adsorption canister and used as the adsorption material in Comparative Example 2. The commercially available adsorption canister used was model number 14950-01FOA (Nissan Motor Co., Ltd.).

[0334] <Comparative Example 3: Granular Activated Carbon>

[0335] Granular activated carbon was removed from the commercially available adsorption vessel and used as the adsorption material in Comparative Example 3. The commercially available adsorption vessel used was model 1K0201801E (Volkswagen).

[0336] For the activated carbons used in Examples 1 and 2 and Comparative Examples 1-3, the measured values ​​for the above-mentioned physical properties were obtained according to the above-described test methods. The results are shown in Table 1. In addition, the characteristics of the molded adsorbents of Examples 1 and 2 and Comparative Examples 1-3 are shown in Tables 2-1 and 2-2, respectively.

[0337] [Table 1]

[0338]

[0339] [Table 2-1]

[0340]

[0341] [Table 2-2]

[0342]

[0343] As shown in the results of Examples 1 and 2 in Table 2-1, using the specified activated carbon, it is possible to prepare shaped adsorbates with excellent adsorption and desorption properties. Furthermore, it is also found that the 0 ppm retention time of the shaped adsorbates in Examples 1 and 2 is superior to that in Comparative Examples 1-3.

[0344] Explanation of reference numerals in the attached figures

[0345] 1. Stacked adsorbent, 10. Sheet-shaped shaped adsorbent, 10a. Main surface of sheet-shaped shaped adsorbent, 10b. Side end surface of sheet-shaped shaped adsorbent, 10c. Side end surface of sheet-shaped shaped adsorbent, F. Flow direction of gas, 2. Disc-shaped shaped adsorbent, 3. Cylindrical shaped adsorbent.

Claims

1. Molded adsorbent, which is a molded adsorbent used in adsorption tanks. The molded adsorbent comprises activated carbon and a binder. Regarding the ratio of activated carbon to binder, the binder comprises 0.3 to 20 parts by weight relative to 100 parts by weight of activated carbon. With respect to the shaped adsorbent body, P represented by the following formula 1 is 18% or more 0.2 / 100 is 18% or more, P 0.2 / 100 = X ÷ Y x 100... (Formula 1), and P represented by the following formula 2 100 / 50 is 120% or less, P 100 / 50 =Y÷Z×100···(Equation 2) In Formula 1, X represents the amount of n-butane gas adsorbed per 100 parts by weight of the molded adsorbent in an atmosphere of 25°C and n-butane gas pressure of 0.2 kPa, and Y represents the amount of n-butane gas adsorbed per 100 parts by weight of the molded adsorbent in an atmosphere of 25°C and n-butane gas pressure of 100 kPa. In Formula 2, Z represents the amount of n-butane gas adsorbed per 100 parts by weight of the shaped adsorbent in an atmosphere of 25°C and 50 kPa pressure of n-butane gas, and Y is the same as Y in Formula 1. The unit for the amount of n-butane gas adsorbed is parts by weight.

2. The molded adsorbent as described in claim 1, wherein, The P 0.2 / 100 is 21% or more.

3. The molded adsorbent as described in claim 1, wherein, The P 100 / 50 is 115% or less.

4. The molded adsorbent as described in claim 1, wherein, The effective adsorption-desorption rate of n-butane in the shaped adsorbent is above 50.0%.

5. The molded adsorbent as described in claim 1, wherein, The specific surface area of ​​the shaped adsorbent is 2500 m². 2 / g or less.

6. The molded adsorbent as described in claim 1, wherein, The total pore volume of the molded adsorbent is 0.50–1.20 cm³. 3 .

7. The molded adsorbent as described in claim 1, wherein, The average pore size of the shaped adsorbent is 1.50–2.00 nm.

8. The molded adsorbent as described in claim 1, wherein, The density of the molded adsorbent is 0.010–0.400 g / cm³. 3 .

9. The molded adsorbent as described in claim 1, wherein, The activated carbon includes activated carbon fibers.

10. The molded adsorbent as described in claim 1, wherein, The molded adsorbent is used in adsorption cans for use in automobiles.

11. An adsorption tank comprising the shaped adsorbent body according to any one of claims 1 to 9.

12. The adsorption tank as described in claim 11, wherein, The adsorption tank is an adsorption tank used in automobiles.

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