JP2022132348A - Activated carbon and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an activated carbon that has a high total trihalomethane filtration ability even in a water passage treatment performed at a high superficial velocity (SV).

SOLUTION: An activated carbon is provided which has a total pore volume T of 0.3 to 1.5 (cc/g) as calculated by QSDFT method. In the activated carbon, a ratio (A/T) of a pore volume A (cc/g) of pore diameters in the range not more than 0.8 nm of a pore volume as calculated by the QSDFT method with respect to the total pore volume T (cc/g) as calculated by the QSDFT method is 0.5 to 0.7; and a ratio (B/T) of a pore volume B (cc/g) of pore diameters in the range from 2.5 to 3.0 nm of a pore volume as calculated by the QSDFT method with respect to the total pore volume T (cc/g) as calculated by the QSDFT method is 0.02 to 0.06.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to activated carbon and a method for producing the same, and more particularly to activated carbon and a method for producing the same that are excellent in the ability to filter trihalomethane under high superficial velocity.

Chlorine is conventionally added to tap water and the like used for drinking purposes for the purpose of sterilization. However, chlorine contained in tap water reacts with organic substances contained in tap water to produce organic halogen compounds. For example, it is known that humic substances, which are natural organic substances, react with chlorine in tap water to produce trihalomethanes, which are carcinogenic substances. Activated carbon has been proposed which is excellent in filtering these organic halogen compounds contained in tap water.

As an activated carbon excellent in the ability to filter organic halogen compounds, for example, the pore volume ratio of pores with a pore diameter of 20 Å to 100 Å (2 nm to 10 nm) to the pore volume of 100 Å (10 nm) or less is 5 to 50%. There is known an adsorbent containing porous carbon having a pore volume ratio of 45% or more with a pore diameter of 10 Å (1 nm) or less (see, for example, Patent Document 1). In the adsorbent, the pore volume ratio of pores with a pore diameter of 20 Å to 100 Å is 5 to 50% with respect to the pore volume of pores with a pore diameter of 100 Å or less. This is to increase the target adsorption force. On the other hand, in the adsorbent, since it is also necessary to increase the equilibrium adsorption amount, which is the static adsorption force, the pore volume ratio of pores with a diameter of 10 Å or less, which is effective for the static equilibrium adsorption amount, should be 45% or more. disclosed. The adsorbent is said to be able to achieve both static adsorption force and dynamic adsorption force by having such a structure.

In addition, in the pore size distribution obtained by the BJH method from the nitrogen adsorption isotherm at 77.4 K, the mesopore volume in the range of pore diameters of 30 Å or more and less than 50 Å is 0.02 to 0.40 cc / g, and all Activated carbon in which the ratio of the mesopore volume in the above range to the pore volume is 5 to 45% is known (see, for example, Patent Document 2). According to the activated carbon, by controlling the volume of the mesopores (pores with a diameter of 2 to 50 nm) and the ratio within the above range, it is a material suitable for adsorption of various substances to be adsorbed (especially trihalomethanes). It is said that it can be done.

JP 2006-247527 A JP 2004-182511 A

In recent years, water purification filters containing such activated carbon are required to have a high total trihalomethane filtering capacity. For example, water purification filters are required to have a large total filtered water volume of total trihalomethanes (amount of water until the total trihalomethane removal rate drops to 80%) in JIS S3201 "Volatile Organic Compound Filtration Ability Test". ing. The larger the total amount of filtered water, the longer the usable period (replacement period) of the water purification filter.

In addition, when the water filter is for a faucet-integrated water purifier, the size of the water filter needs to be reduced. As the water purification filter becomes smaller, the superficial velocity (SV) becomes larger, making it difficult to maintain a high total trihalomethane filtration capacity.

As a result of studies by the present inventors, the activated carbons disclosed in Patent Documents 1 and 2 are evaluated under the condition of SV of 1000 h ^-1 , and the conditions of large superficial velocity (for example, SV of about 3000 h ^-1 ) It was found that there was a problem in that the filtration capacity of all trihalomethanes could not be exhibited sufficiently under the conditions.

SUMMARY OF THE INVENTION The main object of the present invention is to solve the above problems and to provide an activated carbon having a high total trihalomethane filtration capacity even in water flow treatment at a high superficial velocity (SV), and a method for producing the same.

At first, according to the studies of the present inventors, it was thought that trihalomethane molecules were likely to be adsorbed in pores of 1.5 nm or less. However, the present inventors considered that the rate at which trihalomethane molecules diffuse into pores is also an important factor when considering filtration of all trihalomethane molecules under a large SV. Therefore, the present inventors have repeatedly studied from these points of view, and controlled the pore diameter and pore volume of the activated carbon, specified the ratio of the pore volume of 0.8 nm or less to the total pore volume, and It was found that by setting the ratio of the pore volume having a pore diameter of 2.5 nm or more and 3.0 nm or less to the total pore volume within a specific range, a high total trihalomethane filtering ability is obtained even under a large SV.

For example, the invention disclosed in Patent Document 1 attempts to increase the dynamic adsorptive power by controlling the pore volume of 2 to 10 nm, which is a wide pore diameter range among mesopores. However, in the invention, for example, to improve the filtration ability under a high SV such as 3000 h ^-1 , control is not considered. In fact, the activated carbon specifically disclosed as an example in the same document has a small ratio of the pore volume with a pore diameter of 2.5 nm or more and 3.0 nm or less to the total pore volume, and under the condition of a large superficial velocity The filtration capacity of total trihalomethanes cannot be sufficiently exhibited.

Further, for example, the invention disclosed in Patent Document 2 discloses controlling the pore volume in the range of relatively large pore diameters of 3 to 5 nm. In addition, as a control method, pitch containing 0.01 to 5% by weight of at least one metal component of Mg, Mn, Fe, Y, Pt and Gd is used as an activated carbon precursor, and the precursor is infusible. Alternatively, in the method of carbonizing and activating, the mesopore mode diameter of the obtained activated carbon is controlled by changing the type of the metal component. It is disclosed that added activated carbon exhibits the best effect as an adsorbent for removing organic compounds in water. Further, as a practical embodiment, a method of adding Fe to the activated carbon precursor and activating with steam is disclosed. However, even in the present invention, it is necessary to improve the filtration ability under a high SV such as 3000 h ^-1 , and the ratio of the pore volume with a pore diameter of 2.5 nm or more and 3.0 nm or less to the total pore volume is not considered to control According to the studies of the present inventors, in the method of adding Fe to the activated carbon precursor and activating with steam, which is specifically disclosed as an example in Patent Document 2, relatively large pore diameters of 3 to 5 nm are used. Although the pore volume in the range can be increased, the pore volume in the pore diameter range of 0.8 nm or less and the pore volume in the pore diameter range of 2.5 nm to 3.0 nm are sufficiently large. Therefore, it was found that the filtration capacity of all trihalomethanes could not be exhibited sufficiently under the condition of high superficial velocity.

The present invention is an invention completed by further studies based on these findings.

That is, the present invention provides inventions in the following aspects.
Section 1. The total pore volume T calculated by the QSDFT method is 0.3 to 1.5 (cc/g),
Pore volume A (cc/g) with a pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method with respect to the total pore volume T (cc/g) calculated by the QSDFT method The ratio (A / T) is 0.5 to 0.7,
Pore volume B (cc / Activated carbon whose ratio (B/T) of g) is from 0.02 to 0.06.
Section 2. Item 2. The activated carbon according to Item 1, wherein the pore volume of pores having a diameter of 3.0 nm or more is 0.02 (cc/g) or less in the pore volume calculated by the QSDFT method.
Item 3. The activated carbon according to claim 1 or 2, having a specific surface area of 700 m ² /g or more and 2500 m ² /g or less.
Section 4. Item 4. The activated carbon according to any one of items 1 to 3, containing molybdenum elemental substance and/or a molybdenum compound inside the activated carbon.
Item 5. 5. The activated carbon according to any one of Items 1 to 4, which has a total trihalomethane filtration capacity of 50 L/g or more.
Item 6. Any one of Items 1 to 5, comprising a step of activating an activated carbon precursor containing 0.1 to 1.0% by mass of molybdenum at an ambient temperature of 900 to 1000° C. in a gas atmosphere having a CO ₂ concentration of 50% by volume or more. 2. A method for producing activated carbon according to item 1.

The activated carbon of the present invention has a total pore volume T calculated by the QSDFT method of 0.3 to 1.5 (cc/g), and a total pore volume T calculated by the QSDFT method (cc/g ), the ratio (A / T) of the pore volume A (cc / g) of the pore diameter in the range of 0.8 nm or less in the pore volume calculated by the QSDFT method is 0.5 to 0.7 , the pore volume B (cc /g) ratio (B/T) is 0.02 to 0.06. Since the activated carbon of the present invention has such a structure, it is possible to obtain an activated carbon having a high total trihalomethane filtering capacity even in water flow treatment at a high superficial velocity (SV).

4 is a graph showing the pore size distribution of the activated carbon of Example 1 calculated by the QSDFT method. 4 is a graph showing the pore size distribution of the activated carbon of Example 2 calculated by the QSDFT method. 4 is a graph showing the pore size distribution of activated carbon of Comparative Example 1 calculated by the QSDFT method. 4 is a graph showing the pore size distribution of activated carbon of Comparative Example 2 calculated by the QSDFT method. 10 is a graph showing the pore size distribution of activated carbon of Comparative Example 3 calculated by the QSDFT method.

The activated carbon of the present invention will be described in detail below.

The activated carbon of the present invention has a total pore volume T calculated by the QSDFT method of 0.3 to 1.5 (cc/g), and a total pore volume T calculated by the QSDFT method (cc/g ), the ratio (A / T) of the pore volume A (cc / g) of the pore diameter in the range of 0.8 nm or less in the pore volume calculated by the QSDFT method is 0.5 to 0.7 , the pore volume B (cc /g) ratio (B/T) is 0.02 to 0.06.

In order to have a high total trihalomethane filtration ability even under a large SV, the ratio (A / T) of the pore volume A of 0.8 nm or less to the total pore volume T is set to a specific range, and the total pore volume T It is important to set the ratio (B/T) of the pore volume B with a pore diameter of 2.5 nm or more and 3.0 nm or less to the specific range. According to studies by the present inventors, pores of 0.8 nm or less easily adsorb trihalomethane molecules, and pores of 2.5 nm or more and 3.0 nm or less adsorb trihalomethane molecules. It is thought that it also contributes to the diffusion of As a result of repeated studies by the present inventors, it was found that the pore volume A of 0.8 nm or less and the pore volume B of 2.5 nm or more and 3.0 nm or less should not simply be increased. It has also been found that a specific range of ratios to the pore volume T is important. Therefore, according to the activated carbon of the present invention, the ratio (A/T) of the pore volume A of 0.8 nm or less to the total pore volume T and the pore diameter of 2.5 nm or more and 3.0 nm or less to the total pore volume T By adjusting the ratio of the pore volume B (B/T) in the specific range, it is possible to exhibit a high total trihalomethane filtration ability even under a large SV.

In the present invention, the pore volume in a specific pore size range is calculated by the QSDFT method. The QSDFT method (quenched solid density functional theory) is a geometrically and chemically irregular microporous mesoporous carbon pore size distribution from about 0.5 nm to about 40 nm. It is an analysis method that can calculate The QSDFT method clearly takes into account the effects of pore surface roughness and non-uniformity, and is therefore a technique that greatly improves the accuracy of pore size distribution analysis. In the present invention, "AUTOSORB-1-MP" manufactured by Quantachrome is used to measure the nitrogen adsorption isotherm and analyze the pore size distribution by the QSDFT method. By applying _N at 77K on carbon [slit pore, QSDFT equilibrium model] as a calculation model to the desorption isotherm of nitrogen measured at a temperature of 77 K to calculate the pore size distribution, the specific pore size range Pore volume can be calculated.

The activated carbon of the present invention has a pore volume A ( cc/g) ratio (A/T) is 0.5 to 0.7, and from the viewpoint of making it easier to have a higher total trihalomethane filtration capacity even in water flow treatment at a high superficial velocity (SV). , the ratio is preferably 0.52 to 0.65, particularly preferably 0.54 to 0.58.

The activated carbon of the present invention has pores with a pore diameter in the range of 2.5 to 3.0 nm in the pore volume calculated by the QSDFT method with respect to the total pore volume T (cc/g) calculated by the QSDFT method. The ratio (B/T) of the volume B (cc/g) is 0.02 to 0.06, and it tends to have a higher total trihalomethane filtration capacity even in water flow treatment at a high superficial velocity (SV). From the point of view that the ratio is 0.03-0.05.

From the viewpoint of making it easier to have a higher total trihalomethane filtration ability even in water flow treatment at a high superficial velocity (SV), the activated carbon of the present invention has a pore volume of 0.8 nm or less calculated by the QSDFT method. The pore volume A (cc/g) of the pore diameter in the range of is preferably 0.15 to 1.05 cc/g, more preferably 0.15 to 0.40 cc/g, and 0.20 ~0.35 cc/g is particularly preferred.

From the viewpoint of making it easier to have a higher total trihalomethane filtration capacity even in water flow treatment at a large superficial velocity (SV), the activated carbon of the present invention has a pore volume of 2.5 to 2.5 out of the pore volumes calculated by the QSDFT method. The pore volume B (cc/g) of the pore diameter in the range of 3.0 nm is preferably 0.009 to 0.09 cc/g, more preferably 0.009 to 0.04 cc/g, Particularly preferred is 0.01 to 0.03 cc/g.

From the viewpoint of making it easier to have a higher total trihalomethane filtration ability even in water flow treatment at a high superficial velocity (SV), the activated carbon of the present invention has a pore volume of 2.0 nm or less calculated by the QSDFT method. The pore volume C (cc/g) of the pore diameter in the range of is preferably 0.3 to 0.6 cc/g, more preferably 0.35 to 0.50 cc/g, and 0.46 ~0.50 cc/g is particularly preferred.

From the viewpoint of making it easier to have a higher total trihalomethane filtration ability even in water flow treatment at a high superficial velocity (SV), the activated carbon of the present invention has a pore volume of 2.0 nm or more as calculated by the QSDFT method. The pore volume D (cc/g) of the pore diameter is preferably 0.01 to 0.05 cc/g, more preferably 0.01 to 0.03.

From the viewpoint of making it easier to have a higher total trihalomethane filtration ability even in water flow treatment at a high superficial velocity (SV), the activated carbon of the present invention has a pore volume of 3.0 nm or more as calculated by the QSDFT method. is preferably 0.02 cc/g or less, more preferably 0.01 cc/g or less, and particularly preferably 0.001 cc or less.

From the viewpoint of making it easier to have a higher total trihalomethane filtration capacity even in water flow treatment at a high superficial velocity (SV), the activated carbon of the present invention has a pore volume of 2.0 to 2.0 out of the pore volumes calculated by the QSDFT method. The pore volume F (cc/g) of pore diameters in the range of 2.5 nm is preferably 0.01 cc/g or less, more preferably 0.005 cc/g or less, and 0.001 cc/g or less. is particularly preferred.

From the viewpoint of making it easier to have a higher total trihalomethane filtration ability even in water flow treatment at a high superficial velocity (SV), the activated carbon of the present invention has a pore volume of 2.0 nm or less calculated by the QSDFT method. The ratio of the pore volume A (cc/g) with a pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method to the pore volume C (cc/g) with a pore diameter in the range of A/C) is preferably 0.5 to 0.7, more preferably 0.54 to 0.60.

The activated carbon of the present invention has a total pore volume T of 0.3 to 1.5 (cc/g) calculated by the QSDFT method, and even in water flow treatment at a high superficial velocity (SV), it is higher The total pore volume T is preferably 0.3 to 0.8 cc/g, more preferably 0.35 to 0.60 cc/g, from the viewpoint of facilitating the ability to filter the total trihalomethane. 0.40 to 0.55 cc/g is particularly preferred, and 0.48 to 0.53 cc/g is even more preferred.

In the activated carbon of the present invention, the specific surface area of the activated carbon (value measured by the BET method (one-point method) using nitrogen as a substance to be adsorbed) is preferably about 700 to 2500 m ² /g, more preferably 1000 to 1000 m 2 /g. About 2000 m ² /g, particularly preferably about 1000 to 1400 m ² /g.

As will be described later, in the production method of the present invention, the main raw material of the activated carbon precursor (that is, the raw material from which the activated carbon of the present invention is derived) is not particularly limited. Infusible resins such as resins can be used, and examples of the organic material include polyacrylonitrile, pitch, polyvinyl alcohol, and cellulose. Among these, the activated carbon of the present invention is preferably derived from pitch, and more preferably derived from coal pitch.

For the activated carbon of the present invention, one containing a molybdenum compound as an activated carbon precursor is used in order to obtain the above-mentioned specific pore size distribution. The activated carbon of the present invention may contain molybdenum alone and/or a molybdenum compound derived from the molybdenum compound contained in the activated carbon precursor. The ratio (total) of the mass of molybdenum simple substance and molybdenum compound contained in the activated carbon in the total mass of the activated carbon of the present invention is, for example, 0.2 to 1.0% by mass, and 0.3 to 0. 0.8% by mass is preferred. The above ratio is the ratio of molybdenum element conversion (that is, the content of molybdenum) measured by an ICP emission spectrometer (model 715-ES manufactured by Varian).

The form of the activated carbon of the present invention is not particularly limited, but fibrous activated carbon is preferred from the viewpoint of workability when used after being filtered and adsorption speed when used in a water purifier. The average fiber diameter of fibrous activated carbon is preferably 30 μm or less, more preferably about 5 to 20 μm. The average fiber diameter of the fibrous activated carbon of the present invention is a value measured by an image processing fiber diameter measuring device (in accordance with JIS K 1477).

The activated carbon of the present invention has a total pore volume T calculated by the QSDFT method of 0.3 to 1.5 (cc/g), and a total pore volume T calculated by the QSDFT method (cc/g ), the ratio (A / T) of the pore volume A (cc / g) of the pore diameter in the range of 0.8 nm or less in the pore volume calculated by the QSDFT method is 0.5 to 0.7 , the pore volume B (cc /g) ratio (B/T) is 0.02 to 0.06, it is possible to obtain activated carbon having a high total trihalomethane filtration capacity even in water treatment at a high superficial velocity (SV). can. The total trihalomethane filtration capacity of the activated carbon of the present invention in water treatment at a high superficial velocity (SV) is, for example, 50 to 90 L/g, preferably 50 to 70 L/g, at SV of 3000 h ^-1 . mentioned.

The total trihalomethane filtering capacity (L/g) is measured by the following method. That is, after drying activated carbon in a dryer at 105° C. for 2 hours or longer, 3.0 g of the dried carbon is sampled, beaten with a mixer, and filled in a glass column. A glass column having a diameter of 25 mm is used and packed to a height of 41 mm. Prepare sample water with a total trihalomethane (CHCl ₃ :CHCl ₂ Br:CHClBr ₂ :CHBr ₃ =45:30:20:5) concentration of 100±20 ppb based on JIS-S-3201 “Household water purifier test method”. Then, the water temperature is controlled to 20°C ± 1°C, and the water is passed through the activated carbon column at a superficial velocity of 3000 h ^-1 . The concentrations of sample water and filtered water are measured by the headspace method using a non-radiation source type electron capture detector (GC7000EN, manufactured by J Science Lab Co., Ltd.). The sample water is continuously passed through until the total trihalomethane removal rate of the filtered water falls below 80%, and the water flow rate (L/g) at which the removal rate is 80% is taken as the total trihalomethane adsorption capacity of the activated carbon.

Next, the method for producing activated carbon of the present invention will be described in detail.

The method for producing activated carbon of the present invention includes a step of activating an activated carbon precursor containing 0.1 to 1.0% by mass of molybdenum in a gas atmosphere having a CO ₂ concentration of 50% by volume or more at an ambient temperature of 900 to 1000°C. preferably included.

Conventionally, in the case of water purification applications, particularly activated carbon for removing low-molecular-weight organohalogen compounds such as trihalomethane, a method of activating an activated carbon precursor in an atmosphere containing a large amount of water vapor has been widely used. For example, Patent Literature 1 discloses, as a feasible method, fullerene as an activated carbon precursor and activation in an atmosphere of water vapor/nitrogen=50/50 (volume ratio). However, as described above, the activated carbon disclosed in Patent Document 1 has a small pore volume ratio of pore diameters in the range of 2.5 nm or more and 3.0 nm or less. In the above method, even if an attempt is made to increase the volume ratio of pore diameters in the range of 2.5 nm or more and 3.0 nm or less by, for example, increasing the activation time, the range of 0.8 nm or less The ratio of the pore diameter to the pore volume is reduced.

Moreover, in Patent Document 2, an activated carbon precursor containing at least one metal component of Mg, Mn, Fe, Y, Pt and Gd is disclosed in order to set the volume of pores having a pore diameter of 30 Å or more and less than 50 Å in a specific range. A method of activating the body in the presence of nitrogen and saturated water vapor is disclosed. However, in this method, according to the study of the present inventors, the pore volume with a pore diameter in the range of 0.8 nm or less and the pore volume with a pore diameter in the range of 2.5 nm or more and 3.0 nm or less is sufficiently large. cannot be assumed. In the above method, even if the activation is further advanced by, for example, increasing the activation time, only pores having a pore diameter of 30 Å or more and less than 50 Å are developed, and the pores are 2.5 nm or more and 3.0 nm. The pore volume cannot be increased for pore diameters within the following range.

On the other hand, in the production method of the present invention, an activated carbon precursor containing 0.1 to 1.0% by mass of molybdenum is activated using an activating gas containing 50% by volume or more of CO ₂ , which reacts more slowly than steam. , While maintaining the ratio of the pore volume in the range of pore diameters of 0.8 nm or less, it is possible to control the ratio of the pore volume of pore diameters in the range of 2.5 nm or more and 3.0 nm or less to a specific range. It becomes possible.

In the production method of the present invention, the main raw material of the activated carbon precursor is not particularly limited. Examples thereof include infusible or carbonized organic materials, infusible resins such as phenolic resins, etc. Examples of the organic materials include polyacrylonitrile, pitch, polyvinyl alcohol, cellulose, and the like. From the viewpoint of the theoretical carbonization yield during carbonization, pitch is preferable, and among pitches, coal pitch is particularly preferable.

In the production method of the present invention, the content of molybdenum in the activated carbon precursor is preferably 0.1 to 1.5% by mass, more preferably 0.4 to 1.2% by mass. Molybdenum can be contained by mixing molybdenum alone or molybdenum compounds with raw materials. Molybdenum compounds include inorganic metal compounds such as metal oxides, metal hydroxides, metal halides, and metal sulfates containing molybdenum as a constituent metal element, salts of organic acids such as acetic acid and metals, and organic metal compounds. is mentioned. Examples of organometallic compounds include metal acetylacetonates and aromatic metal compounds.

In the production method of the present invention, the gas atmosphere for activation has a CO ₂ concentration of 50% by volume or more, preferably 95% by volume or more, more preferably 99% by volume or more. As described above, when CO ₂ is used as the activating gas, the reaction progresses slowly. Therefore, the higher the CO ₂ concentration, the easier it is to adjust the pore size distribution, and the easier to obtain the activated carbon of the present invention.

Components other than CO ₂ in the activation gas atmosphere include N ₂ , O ₂ , H ₂ , H ₂ O, and CO.

In the production method of the present invention, the ambient temperature for activation is usually about 800 to 1000°C, preferably about 900 to 980°C. The activation time may be adjusted according to the main raw material of the activated carbon precursor, the content of molybdenum, the CO ₂ concentration in the activation gas, etc., so as to obtain a predetermined pore size distribution. For example, pitch having a softening point of 275° C. to 288° C. is used as the main raw material of the activated carbon _precursor , and the content of the molybdenum compound in the activated carbon precursor is 0.1 to 5.0 parts by mass. is 100% by volume, the activation is performed at an atmosphere temperature of 900 to 1000° C. for an activation time of 10 to 50 minutes, more preferably 20 to 50 minutes.

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. However, the invention is not limited to the examples.

Each example and comparative example was evaluated by the following methods.
(1) Molybdenum content (% by mass) of activated carbon precursor (infusible pitch fiber)
Pitch fibers were ashed, the ash was dissolved in acid, and the molybdenum content was measured by an ICP emission spectrometer (Model 715-ES, manufactured by Varian) in terms of molybdenum element.

(2) Metal content of activated carbon (% by mass)
The molybdenum content was determined by dissolving fibrous activated carbon in acid and using an ICP emission spectrometer (Model 715-ES, manufactured by Varian) in terms of molybdenum element.

(3) Pore volume (cc/g), specific surface area (m ² /g), fiber diameter of fibrous activated carbon (μm)
The pore physical properties were measured from the nitrogen adsorption isotherm at 77K using "AUTOSORB-1-MP" manufactured by Quantachrome. The specific surface area was calculated from the measurement point at a relative pressure of 0.1 by the BET method. The total pore volume T and the pore volume in each pore size range described in Table 1 were obtained by applying _N at 77K on carbon [slit pore, QSDFT equilibrium model] as a calculation model to the measured nitrogen desorption isotherm. was analyzed by calculating the pore size distribution. The results are shown in the graphs of Figures 1-5. The pore volume in each pore size range shown in Table 1 is the reading of the graph showing the pore size distribution shown in FIGS. 1 to 5 or the value calculated from the reading. More specifically, the pore volume A with a pore diameter of 0.8 nm or less is the read value of Cumulative Pore Volume (cc/g) when the horizontal axis Pore Width of the pore diameter distribution diagram is 0.8 nm. Similarly, a pore volume with a pore diameter of 1.0 nm or less, a pore volume C with a pore diameter of 2.0 nm or less, a pore volume with a pore diameter of 2.5 nm or less, and a pore volume with a pore diameter of 3.0 nm or less were obtained. rice field. The pore volume B with a pore diameter in the range of 2.5 to 3.0 nm was calculated by subtracting the pore volume with a pore diameter of 2.5 nm or less from the pore volume with a pore diameter of 3.0 nm or less. The pore volume D with a pore diameter of 2.0 nm or more was calculated by subtracting the pore volume C with a pore diameter of 2.0 nm or less from the total pore volume T. The pore volume E with a pore diameter of 3.0 nm or more was calculated by subtracting the pore volume with a pore diameter of 3.0 nm or less from the total pore volume. The pore volume F in the pore diameter range of 2.0 to 2.5 nm was calculated by subtracting the pore volume of 2.0 nm or less from the pore volume of 2.5 nm or less.

(4) Fiber diameter of fibrous activated carbon (μm)
Measured with an image processing fiber diameter measuring device (according to JIS K 1477).

(5) Total trihalomethane filtration capacity (L/g)
After drying the fibrous activated carbon in a dryer at 105° C. for 2 hours or longer, 3.0 g of the dried carbon was sampled, beaten with a mixer, and filled in a glass column. A glass column with a diameter of 25 mm was used and packed to a height of 41 mm. Prepare sample water with a total trihalomethane (CHCl ₃ :CHCl ₂ Br:CHClBr ₂ :CHBr ₃ =45:30:20:5) concentration of 100±20 ppb based on JIS-S-3201 “Household water purifier test method”. Then, the water temperature was controlled at 20°C ± 1°C, and the water was passed through the activated carbon column at a superficial velocity of 3000 h ^-1 . The concentrations of sample water and filtered water were measured by a headspace method using a non-radiation source type electron capture detector (GC7000EN, manufactured by J Science Lab Co., Ltd.). The sample water was continuously passed until the total trihalomethane removal rate of the filtered water fell below 80%, and the water flow rate (L/g) at which the removal rate was 80% was taken as the total trihalomethane adsorption capacity of the activated carbon.

(Example 1)
As an organic material, 0.8 parts by mass of bis(2,4-pentanedionato)molybdenum (IV) dioxide (metal species Mo) was mixed with 100 parts by mass of granular coal pitch having a softening point of 280°C. The mixture was supplied to a melt extruder, melt-mixed at a melting temperature of 320° C., and spun at a discharge rate of 16 g/min to obtain pitch fibers. The obtained pitch fibers were heated in the air from room temperature to 354° C. at a rate of 1 to 30° C./min for 54 minutes to perform an infusibilization treatment, thereby obtaining an activated carbon precursor as infusible pitch fibers. The content of molybdenum (Mo) in the activated carbon precursor was 0.23% by mass.

The obtained activated carbon precursor was activated by continuously introducing a gas having a CO ₂ concentration of 100% by volume into an activation furnace and heat-treating it at an atmospheric temperature of 950° C. for 34 minutes to obtain the activated carbon of Example 1. rice field. The obtained activated carbon has a total pore volume T calculated by the QSDFT method of 0.43 cc / g, a pore volume A of pore diameters in the range of 0.8 nm or less is 0.26 cc / g, 2.5 to 3 The pore volume B of the pore diameter in the range of .0 nm is 0.01 cc / g, and the pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method for the total pore volume T (cc / g) The ratio (A / T) of the pore volume A (cc / g) is 0.60, and the pore volume calculated by the QSDFT method for the total pore volume T (cc / g) is 2.5 to 3. The pore volume B (cc/g) ratio (B/T) of pore diameters in the range of 0 nm was 0.02, the molybdenum content was 0.41% by mass, and the average fiber diameter was 13.6 μm.

(Example 2)
As an organic material, 0.8 parts by mass of bis(2,4-pentanedionato)molybdenum (IV) dioxide (metal species Mo) was mixed with 100 parts by mass of granular coal pitch having a softening point of 280°C. The mixture was supplied to a melt extruder, melt-mixed at a melting temperature of 320° C., and spun at a discharge rate of 16 g/min to obtain pitch fibers. The obtained pitch fibers were heated in the air from room temperature to 354° C. at a rate of 1 to 30° C./min for 54 minutes to perform an infusibilization treatment, thereby obtaining an activated carbon precursor as infusible pitch fibers. The content of molybdenum (Mo) in the activated carbon precursor was 0.23% by mass.

The obtained activated carbon precursor was activated by continuously introducing a gas having a CO ₂ concentration of 100% by volume into an activation furnace and heat-treating it at an atmospheric temperature of 950° C. for 42 minutes to obtain the activated carbon of Example 2. rice field. The obtained activated carbon has a total pore volume T calculated by the QSDFT method of 0.50 cc/g, a pore volume A of pore diameters in the range of 0.8 nm or less of 0.28 cc/g, and 2.5 to 3 The pore volume B of the pore diameter in the range of .0 nm is 0.02 cc / g, and the pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method for the total pore volume T (cc / g) The ratio (A / T) of the pore volume A (cc / g) is 0.56, and the pore volume calculated by the QSDFT method for the total pore volume T (cc / g) is 2.5 to 3. The pore volume B (cc/g) ratio (B/T) of pore diameters in the range of 0 nm was 0.04, the molybdenum content was 0.47% by mass, and the average fiber diameter was 13.1 μm.

(Comparative example 1)
A test simulating Example 5 of Patent Document 2 was conducted. Specifically, as an organic material, a mixture of 100 parts by mass of granular coal pitch having a softening point of 280 ° C. and 1.3 parts by mass of trisacetylacetonatoitrium was supplied to a melt extruder and melted at a temperature of 320 ° C. and spun at a discharge rate of 20 g/min to obtain pitch fibers. The obtained pitch fibers were heated in the air from room temperature to 354° C. at a rate of 1 to 30° C./min for 54 minutes to perform an infusibilization treatment, thereby obtaining an activated carbon precursor as infusible pitch fibers. The yttrium content in the activated carbon precursor was 0.25 mass %.

The obtained activated carbon precursor was continuously introduced into an activation furnace with a gas having an H ₂ O concentration of 100% by volume, and was heat-treated at an atmospheric temperature of 900° C. for 20 minutes to activate the activated carbon of Comparative Example 1. Obtained. The obtained activated carbon has a total pore volume T calculated by the QSDFT method of 0.57 cc / g, a pore volume A of pore diameters in the range of 0.8 nm or less of 0.15 cc / g, 2.5 to 3 The pore volume B of the pore diameter in the range of .0 nm is 0.05 cc / g, and the pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method for the total pore volume T (cc / g) The ratio (A / T) of the pore volume A (cc / g) is 0.26, and the pore volume calculated by the QSDFT method for the total pore volume T (cc / g) is 2.5 to 3. The pore volume B (cc/g) ratio (B/T) of pore diameters in the range of 0 nm was 0.09, the yttrium content was 0.66% by mass, and the average fiber diameter was 16.5 μm.

(Comparative example 2)
As an organic material, granular coal pitch having a softening point of 280° C. was supplied to a melt extruder, melt-mixed at a melting temperature of 320° C., and spun at a discharge rate of 20 g/min to obtain pitch fibers. The obtained pitch fibers were heated in the air from room temperature to 354° C. at a rate of 1 to 30° C./min for 54 minutes to perform an infusibilization treatment, thereby obtaining an activated carbon precursor as infusible pitch fibers. The yttrium content in the activated carbon precursor was 0% by mass.

The obtained activated carbon precursor was continuously introduced into an activation furnace with a gas having an H ₂ O concentration of 100% by volume, and was heat-treated at an atmospheric temperature of 875° C. for 40 minutes to activate the activated carbon of Comparative Example 2. Obtained. The obtained activated carbon has a total pore volume T calculated by the QSDFT method of 0.48 cc / g, a pore volume A of pore diameters in the range of 0.8 nm or less is 0.33 cc / g, 2.5 to 3 The pore volume B of the pore diameter in the range of .0 nm is 0.00 cc / g, and the pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method for the total pore volume T (cc / g) The ratio (A/T) of the pore volume A (cc/g) is 0.69, and the pore volume calculated by the QSDFT method for the total pore volume T (cc/g) is 2.5-3. The pore volume B (cc/g) ratio (B/T) of pore diameters in the range of 0 nm was 0.00, the yttrium content was 0% by mass, and the average fiber diameter was 16.7 μm.

(Comparative Example 3)
As an organic material, a mixture of 100 parts by mass of granular coal pitch having a softening point of 280°C and 1.0 part by mass of trisacetylacetonatoitrium was supplied to a melt extruder and melt-mixed at a melting temperature of 320°C. , to obtain pitch fibers by spinning at a discharge rate of 16 g/min. The obtained pitch fibers were heated in the air from room temperature to 354° C. at a rate of 1 to 30° C./min for 54 minutes to perform an infusibilization treatment, thereby obtaining an activated carbon precursor as infusible pitch fibers. The yttrium content in the activated carbon precursor was 0.16% by mass.

The obtained activated carbon precursor was activated by continuously introducing a gas having a CO2 concentration of 100% by volume into an activation furnace and heat-treating it at an atmospheric temperature of 950° C. for 40 minutes to obtain activated carbon of Example 3. . The obtained activated carbon has a total pore volume T calculated by the QSDFT method of 0.38 cc / g, a pore volume A of pore diameters in the range of 0.8 nm or less is 0.21 cc / g, 2.5 to 3 The pore volume B of the pore diameter in the range of .0 nm is 0.00 cc / g, and the pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method for the total pore volume T (cc / g) The ratio (A/T) of the pore volume A (cc/g) is 0.55, and the pore volume calculated by the QSDFT method for the total pore volume T (cc/g) is 2.5-3. The pore volume B (cc/g) ratio (B/T) of pore diameters in the range of 0 nm was 0.00, the yttrium content was 0.30% by mass, and the average fiber diameter was 14.2 μm.

Table 1 shows the physical properties of the obtained activated carbon. 1 to 5 show pore size distribution maps calculated by the QSDFT method for the activated carbons of Examples 1 and 2 and Comparative Examples 1 to 3.

The activated carbons of Examples 1 and 2 have a total pore volume T calculated by the QSDFT method of 0.3 to 1.5 (cc/g), and a total pore volume T calculated by the QSDFT method ( cc/g), the ratio (A/T) of the pore volume A (cc/g) with a pore diameter in the range of 0.8 nm or less in the pore volume calculated by the QSDFT method is 0.5 to 0. 7, and the pore volume with a pore diameter in the range of 2.5 to 3.0 nm among the pore volumes calculated by the QSDFT method with respect to the total pore volume T (cc/g) calculated by the QSDFT method. Since the ratio (B/T) of B (cc/g) is 0.02 to 0.06, activated carbon having a high total trihalomethane filtration capacity even in water treatment at a high superficial velocity (SV) can be used. it could be obtained.

In particular, the activated carbon of Example 2 has a total pore volume T calculated by the QSDFT method of the pore volume calculated by the QSDFT method of 0.48 to 0.53 cc / g, and The ratio of the pore volume A (cc/g) with a pore diameter in the range of 0.8 nm or less in the pore volume calculated by the QSDFT method to the total pore volume T (cc/g) calculated (A/ T) is 0.54 to 0.58, and the pore volume calculated by the QSDFT method with respect to the total pore volume T (cc/g) calculated by the QSDFT method is 2.5 to 3.0 nm. Since the ratio (B/T) of the pore volume B (cc/g) of the pore diameter in the range is 0.03 to 0.05, even in the water passage treatment at a large superficial velocity (SV), It was possible to obtain activated carbon having a high total trihalomethane filtration capacity.

On the other hand, in the activated carbon of Comparative Example 1, out of the pore volume calculated by the QSDFT method, the total pore volume T (cc/g) calculated by the QSDFT method is The ratio (A / T) of the pore volume A (cc / g) of the pore diameters in the range of 0.8 nm or less is less than 0.5, and the total pore volume T (cc / g) calculated by the QSDFT method , the ratio (B/T) of the pore volume B (cc/g) of the pore diameter in the range of 2.5 to 3.0 nm out of the pore volume calculated by the QSDFT method exceeds 0.06 For this reason, the total trihalomethane filtering capacity was inferior.

For the activated carbons of Comparative Examples 2 and 3, among the pore volumes calculated by the QSDFT method, the total pore volume T (cc/g) calculated by the QSDFT method is Since the ratio (B/T) of the pore volume B (cc/g) of the pore diameters in the range of 2.5 to 3.0 nm was less than 0.02, the total trihalomethane filtering ability was inferior. rice field.

Claims (6)

The total pore volume T calculated by the QSDFT method is 0.3 to 1.5 (cc/g),
Pore volume A (cc/g) with a pore diameter in the range of 0.8 nm or less among the pore volumes calculated by the QSDFT method with respect to the total pore volume T (cc/g) calculated by the QSDFT method The ratio (A / T) is 0.5 to 0.7,
Pore volume B (cc / Activated carbon whose ratio (B/T) of g) is from 0.02 to 0.06. 2. The activated carbon according to claim 1, wherein the pore volume of pores with a diameter of 3.0 nm or more in the pore volume calculated by the QSDFT method is 0.02 (cc/g) or less. The activated carbon according to claim 1 or 2, having a specific surface area of 700 m ² /g or more and 2500 m ² /g or less. The activated carbon according to any one of claims 1 to 3, containing molybdenum alone and/or a molybdenum compound inside said activated carbon. The activated carbon according to any one of claims 1 to 4, which has a total trihalomethane filtration capacity of 50 L/g or more. 6. The method according to any one of claims 1 to 5, comprising activating an activated carbon precursor containing 0.1 to 1.0% by mass of molybdenum at an ambient temperature of 900 to 1000° C. in a gas atmosphere having a CO ₂ concentration of 50% by volume or more. 1. A method for producing activated carbon according to claim 1.

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