Activated carbon having ultrafine pores and method for manufacturing same

Abstract

Disclosed are: activated carbon having ultrafine pores formed therein by performing primary activation of a raw material in a steam atmosphere and then secondary activation of same in a CO2 gas atmosphere; and a method for manufacturing same. The method for manufacturing activated carbon according to the present invention comprises the steps of: (a) carbonizing a raw material; and (b) activating the carbonized raw material to manufacture activated carbon, wherein the activating is performed by performing primary activation of the carbonized raw material in a steam atmosphere, and then performing secondary activation of same in a CO2 gas atmosphere.

Description

Activated carbon with formed ultrafine pores and method for manufacturing the same

[0001] The present invention relates to activated carbon having a high specific surface area and ultrafine pores formed by first activating the raw material in a steam atmosphere and then secondarily activating it in a CO2 gas atmosphere, and a method for manufacturing the same.

[0002] Among carbon materials, activated carbon is widely used in various fields, ranging from daily life to industrial applications, due to its adsorption properties featuring countless pores.

[0003] Activated carbon is manufactured by forming many pores through carbonization and activation steps using bio-raw materials such as coconut shells, sawdust, charcoal, coal, peat, and pitch.

[0004] For example, activated carbon can be manufactured by physically activating carbon by vaporizing it with water vapor, carbon dioxide, oxygen, etc., or by chemically activating it using acidic and basic activators such as KOH, Na2CO3, H3PO4, etc.

[0005] However, when manufacturing activated carbon, using a single gas such as water vapor or carbon dioxide for activation has the disadvantage of requiring separate surface treatment or chemical treatment during the activation process.

[0006] In addition, when manufacturing activated carbon, activating it using a single gas such as water vapor or carbon dioxide has the disadvantage of significantly increasing the pore size and forming mesopores as the activation time becomes considerably longer to obtain a high specific surface area.

[0007] In addition, when manufacturing activated carbon, using a gas mixed with water vapor and carbon dioxide in a certain ratio for activation has the disadvantage of making it difficult to control the pore shape and pore size.

[0008] Activated carbon activated by this method has a wide distribution of pore sizes ranging from micropores to large pores, resulting in poor uniformity of pore size and difficulty in expressing ultrafine pores smaller than 1 nm.

[0009] Therefore, there is a need for research on activated carbon capable of simultaneously forming high specific surface area and ultrafine pores by controlling activation conditions.

[0010] The objective of the present invention is to provide a method for manufacturing activated carbon having ultrafine pores formed therein, which can control the pore size of the activated carbon having a high specific surface area to 1 nm or less.

[0011] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0012] A method for manufacturing activated carbon according to one embodiment of the present invention comprises: (a) a step of carbonizing a raw material; and (b) a step of activating the carbonized raw material to produce activated carbon; wherein the activation is performed by first activating the carbonized raw material in a steam atmosphere and then secondarily activating it in a CO2 gas atmosphere.

[0013] Primary activation in the above steam atmosphere, 900 ~ 2000m 2 It can form a specific surface area of ​​ / g.

[0014] It is possible to form pore sizes of 1 nm or less by secondary activation in the above CO2 gas atmosphere.

[0015] The primary activation in the above steam atmosphere can be performed for 1 to 3 hours.

[0016] The primary activation in the steam atmosphere and the secondary activation in the CO2 gas atmosphere can be performed at 700 to 1000°C.

[0017] Secondary activation in the above CO2 gas atmosphere can be performed for 1 to 2 hours.

[0018] The above activated carbon may include continuous pores.

[0019] When measuring the elemental content of the activated carbon by ICP analysis, the elemental content of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) may be 210 ppm or less.

[0020] The above raw materials may include one or more of heavy tar, coal tar, coke, furan resin, sawdust, coconut shells, coffee grounds, bamboo, pruned wood, rice bran, kenaf, rice husk, malt residue, reed grass, coal-based pitch, petroleum-based pitch, anthracite, and green coke fine powder.

[0021] The step of carbonizing the raw material (a) above may include (a1) a step of pre-treating the raw material; and (a2) a step of carbonizing the pre-treated raw material after compression molding.

[0022] The carbonization above can be performed in a reducing atmosphere at 700 to 900°C, and the reducing atmosphere can be performed in an inert gas atmosphere of one or more of nitrogen, argon, and hydrogen.

[0023] A method for manufacturing activated carbon according to another embodiment of the present invention includes the step of manufacturing activated carbon by activating a raw material, wherein the activation is performed by first activating the raw material in a steam atmosphere and then secondarily activating it in a CO2 gas atmosphere.

[0024] A method for manufacturing activated carbon according to another embodiment of the present invention comprises the step of manufacturing activated carbon by activating a raw material, wherein the activation is performed by first activating the raw material in a steam atmosphere at 900 to 2000 m2 It is characterized by forming a specific surface area of ​​ / g.

[0025] A method for manufacturing activated carbon according to another embodiment of the present invention includes the step of manufacturing activated carbon by activating a raw material, wherein the activation is performed by first activating the raw material and then secondarily activating it in a CO2 gas atmosphere.

[0026] A method for manufacturing activated carbon according to another embodiment of the present invention comprises the step of manufacturing activated carbon by activating a raw material, wherein the activation involves primary activation of the raw material to 900 to 2000 m 2 It is characterized by forming a specific surface area of ​​ / g and then performing secondary activation to form a pore size of 1 nm or less.

[0027] A method for manufacturing activated carbon according to another embodiment of the present invention comprises: (a) a step of carbonizing a raw material; and (b) a step of activating the carbonized raw material to produce activated carbon; wherein the activation is performed by first activating the carbonized raw material in a steam atmosphere at 900 to 2000 m 2 It is characterized by forming a specific surface area of ​​ / g.

[0028] A method for manufacturing activated carbon according to another embodiment of the present invention comprises: (a) a step of carbonizing a raw material; and (b) a step of activating the carbonized raw material to produce activated carbon; wherein the activation is performed by first activating the carbonized raw material and then secondarily activating it in a CO2 gas atmosphere.

[0029] A method for manufacturing activated carbon according to another embodiment of the present invention comprises: (a) a step of carbonizing a raw material; and (b) a step of activating the carbonized raw material to manufacture activated carbon; wherein the activation is performed by first activating the carbonized raw material to 900 to 2000 m 2 It is characterized by forming a specific surface area of ​​ / g and then performing secondary activation to form a pore size of 1 nm or less.

[0030]

[0031] Activated carbon according to one embodiment of the present invention is porous activated carbon and is characterized by containing ultrafine pores with a size of 1 nm or less, and having an elemental content of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) of 210 ppm or less when elemental content is measured by ICP analysis.

[0032] When measuring elemental content by ICP analysis, the elemental content of potassium (K) may be 210 ppm or less.

[0033] When measuring elemental content by ICP analysis, the elemental content of iron (Fe) may be 150 ppm or less.

[0034] The above activated carbon is 900 ~ 2000m 2 It can have a specific surface area of ​​ / g.

[0035] Activated carbon includes ultrafine pores of 1 nm or less and micropores of more than 1 nm to 2 nm or less, wherein the ultrafine porosity among the total pores may be higher than the microporosity.

[0036] The above activated carbon may include continuous pores.

[0037]

[0038] Activated carbon according to another embodiment of the present invention is porous activated carbon, characterized in that, when elemental content is measured by ICP analysis, the elemental content of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) is 210 ppm or less.

[0039] Activated carbon according to another embodiment of the present invention is porous activated carbon, comprising ultrafine pores of 1 nm or less and micropores greater than 1 nm and 2 nm or less, characterized in that the ultrafine porosity among the total pores is higher than the microporosity.

[0040] Activated carbon according to another embodiment of the present invention is porous activated carbon, comprising ultrafine pores with a size of 1 nm or less, and is characterized by having an elemental content of potassium (K) of 210 ppm or less when elemental content is measured by ICP analysis.

[0041] Activated carbon according to another embodiment of the present invention is porous activated carbon, comprising ultrafine pores with a size of 1 nm or less, and is characterized by having an elemental content of iron (Fe) of 150 ppm or less when elemental content is measured by ICP analysis.

[0042] Activated carbon according to another embodiment of the present invention is porous activated carbon containing continuous pores, and is characterized by having an elemental content of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) of 210 ppm or less when elemental content is measured by ICP analysis.

[0043] Under the existing activation conditions in which a steam atmosphere and a CO2 gas atmosphere are mixed in a certain ratio, it was difficult to control the size of ultrafine pores while securing a high specific surface area of ​​activated carbon, but the method for manufacturing activated carbon according to the present invention improves this problem and has the effect of forming ultrafine pores with a pore size of 1 nm or less in activated carbon with a high specific surface area.

[0044] In addition, the activation conditions utilizing a steam atmosphere and a CO2 gas atmosphere of the present invention have the advantage of not requiring separate surface treatment or chemical treatment compared to conventional chemical activation conditions or activation conditions utilizing a steam atmosphere or a CO2 gas atmosphere alone.

[0045] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0046] Figure 1 is a schematic diagram showing the pore shape of chemical activation.

[0047] Figure 2 is a schematic diagram showing the pore shape of physical activation.

[0048] FIG. 3 is a schematic diagram showing the pore shape of a carbonized raw material according to the present invention, which is first activated in a steam atmosphere and then secondarily activated in a CO2 gas atmosphere.

[0049] Figure 4 is a graph showing the pore area according to the pore size distribution of pores formed by activation in a steam atmosphere or a CO2 gas atmosphere.

[0050] Figure 5 is a graph showing the volume of adsorbed nitrogen according to the partial pressure of the pores formed by activation in a steam atmosphere.

[0051] Figure 6 is a graph showing the pore area according to pore size using the sample of Figure 5.

[0052] Figure 7 is a graph showing the pore area according to pore size for Comparative Example 1 (1 hour in a steam atmosphere), Comparative Example 2 (6 hours in a CO2 gas atmosphere), and Example 1 (2.5 hours in a CO2 gas atmosphere after a steam atmosphere).

[0053] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0054] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0055] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0056] Hereinafter, a method for manufacturing activated carbon with ultrafine pores formed therein according to some embodiments of the present invention will be described.

[0057] As its name suggests, activated carbon is an aggregate of amorphous carbon composed primarily of carbon with well-developed micropores. Activated carbon possesses the characteristic of adsorbing molecules of the adsorbate by exerting attractive forces on surrounding liquids or gases through the functional groups of carbon atoms present on its surface.

[0058] To manufacture activated carbon, a step of activating the raw materials is performed.

[0059] The activation step is a process that develops micropores in the carbide by eroding its surface through a carbon oxidation reaction occurring within the heat treatment temperature range.

[0060] The activation step is performed to form a high specific surface area on the activated carbon and is divided into chemical activation and physical activation.

[0061] Figure 1 is a schematic diagram showing the pore shape of chemical activation, and Figure 2 is a schematic diagram showing the pore shape of physical activation.

[0062] Chemical activation is a method of chemically activating using acidic and basic activators.

[0063] As shown in Fig. 1, upon chemical activation, the pore shape is relatively sharp and long.

[0064] Chemical activation includes closed pores, which are formed with a structure in which the walls of the pores are all closed and are not connected to other pores.

[0065] Chemical activation has the advantage of forming irregular shapes with a high specific surface area, as many functional groups are formed on the surface of activated carbon due to chemical reactions during pore formation.

[0066] However, chemical activation has the disadvantages of requiring pH control, which is difficult to achieve, and necessitating a rinsing process. Additionally, chemical activation contributes to environmental pollution and has the drawback of high manufacturing costs.

[0067] Physical activation is a method of physically activating carbon by vaporizing it with water vapor, carbon dioxide, oxygen, etc.

[0068] As shown in FIG. 2, unlike the pore shape of FIG. 1, when physically activated, at least a portion of the wall surface of the pore is formed into an open structure and includes a continuous pore (opened pore, connected pore) as a pore connected to another pore.

[0069] Physical activation is characterized by having uniform pore size during continuous pore formation and forming large spaces with complex, wide, and deep structures within the pores.

[0070] Physical activation has the advantage of low activation and maintenance costs, but because the pore shapes are interconnected, they tend to collapse easily; for this reason, the specific surface area decreases as the pore distribution increases.

[0071] In addition, physical activation has the disadvantage of making it difficult to control ultrapores.

[0072] Accordingly, the inventor controlled the physical activation conditions after extensive research.

[0073] The inventors first activated the raw material in a steam atmosphere to secure a high specific surface area while maintaining the shape of continuous pores. Then, after the first activation, they secondarily activated it in a CO2 gas atmosphere to form mainly ultrafine pores (size of 1 nm or less).

[0074] In a steam atmosphere, the activation speed was fast, but after reaching a certain level of activation, the rate at which the pore shape collapsed was faster than the rate of pore formation. This meant that the formation rate of mesopores was faster than that of ultrafinepores.

[0075] In a CO2 gas atmosphere, the activation speed was slower than in a steam atmosphere, but it was more advantageous for forming ultrafine pores.

[0076] In a CO2 gas atmosphere, the difference between the pore formation rate and the pore shape collapse rate is smaller than in a steam atmosphere, making it advantageous for forming ultrafine pores.

[0077] Based on these research results, the inventors confirmed that utilizing a combination of a steam atmosphere and a CO2 gas atmosphere, but activating the raw material first in a steam atmosphere followed by activation in a CO2 gas atmosphere, has a significant effect on the formation of high specific surface area and ultrafine pores in activated carbon.

[0078] Therefore, through the condition of primary activation in a steam atmosphere followed by secondary activation in a CO2 gas atmosphere, the activated carbon of the present invention is 900m 2 It showed the effect of simultaneously maintaining a high specific surface area of ​​more than / g and ultrafine pores with a pore size of 1nm or less.

[0079] The effect of this invention is an improved effect compared to the existing single activation conditions utilizing a steam atmosphere or a CO2 gas atmosphere, and the existing activation conditions mixing a steam atmosphere and a CO2 gas atmosphere in a certain ratio.

[0080] In the present invention, an ultramicropore refers to a pore with a size of 1 nm or less.

[0081] A micropore refers to a pore with a size of 2 nm or less, specifically a pore with a size greater than 1 nm and less than or equal to 2 nm.

[0082] A mesopore refers to a pore with a size greater than 2 nm and less than or equal to 50 nm.

[0083] The method for manufacturing activated carbon according to the present invention comprises the steps of carbonizing a raw material and activating the carbonized raw material to produce activated carbon, wherein the activation is performed by first activating the carbonized raw material in a steam atmosphere and then secondarily activating it in a CO2 gas atmosphere.

[0084] Step of carbonizing the raw materials

[0085] The step of carbonizing the raw material may include a step of pre-treating the raw material, and a step of carbonizing the pre-treated raw material after compression molding.

[0086] The activated carbon of the present invention can be formed from raw materials including plant-based raw materials, ironmaking process by-products, etc.

[0087] The raw material may include one or more of heavy tar, coal tar, coke, furan resin, sawdust, coconut shells, coffee grounds, bamboo, pruned wood, rice bran, kenaf, rice husk, malt residue, reed grass, coal-based pitch, petroleum-based pitch, anthracite, and green coke fine powder, and preferably may include one or more of coconut shells and coffee grounds.

[0088] Most by-products from the steelmaking process can be obtained from related manufacturers or related fields, thereby reducing manufacturing costs.

[0089] There are no specific limitations on the types of coal-based and petroleum-based pitches, and all coal-based and petroleum-based pitches used in the relevant technical field may be used.

[0090] Green coke refers to coke produced by distilling, refining, and coking coal tar, and also refers to the major solid carbonization product obtained from a high-boiling point hydrocarbon fraction obtained at a temperature of 900K or lower.

[0091] The manufacturing method of the present invention may include a step of pre-treating the raw material to ensure moldability and strength by controlling the residual moisture content of the raw material.

[0092] In this regard, pretreatment can be performed at 100 to 160°C, and preferably at 110 to 150°C.

[0093] By performing pretreatment at 100 to 160°C, the amount of residual moisture in the raw material can be controlled, and excellent strength can be exhibited during the subsequent compression molding stage.

[0094] Activated carbon can be manufactured by compression molding, which involves inserting pre-treated raw materials into molds of various shapes or molding them into various shapes using an extruder or compression molding machine.

[0095] Compression molding offers the advantage of being able to represent the shape of activated carbon.

[0096] To manufacture activated carbon, a carbonization process of the raw material at high temperatures must be involved.

[0097] Carbonization can be performed in a reducing atmosphere at 700 to 900°C, and preferably at 800 to 900°C.

[0098] The reducing atmosphere can be performed in an inert gas atmosphere of one or more of nitrogen, argon, and hydrogen.

[0099] The carbonization time may be performed for 10 minutes to 12 hours, but is not limited thereto.

[0100] The oxygen functional groups on the surface of the activated carbon can be removed through the above reduction treatment, and this can also be effective in improving the lifespan characteristics of the activated carbon.

[0101] By satisfying a carbonization temperature of 700 to 900℃, the carbonization of the raw material can proceed sufficiently.

[0102] Conversely, if the carbonization conditions deviate from a reducing atmosphere and 700 to 900°C, the manufacturing yield and the strength of the activated carbon may decrease.

[0103] Step of manufacturing activated carbon by activating carbonized raw materials

[0104] The reason for activating the above-mentioned carbonized raw material, i.e., the carbonized product, is to form a high specific surface area and ultrafine pores.

[0105] In the present invention, carbonized raw materials are primarily activated in a steam atmosphere to 900 ~ 2000m 2 It can form a specific surface area of ​​ / g, preferably 1300 to 1800 m² 2 It can form a specific surface area of ​​ / g, and more preferably 1500 to 1700 m² 2 It can form a specific surface area of ​​ / g.

[0106] The specific surface area (BET) of the above activated carbon can be measured under N2 gas adsorption conditions using the KS A ISO 9277 method (international standard ISO 9277:2022).

[0107] The activated carbon of the present invention contains continuous pores under physical activation conditions. When carbonized raw materials are activated in a steam atmosphere, the shape of the continuous pores tends to collapse as the activation time increases.

[0108] In other words, after a certain level of activation, the specific surface area of ​​the activated carbon no longer increases, and the pore size also tends to increase.

[0109] From this perspective, it is important to control the activation time and temperature in a steam atmosphere.

[0110] Primary activation in a steam atmosphere can be performed for 1 to 3 hours, preferably for 1 to 2 hours, more preferably for 1 to 1.5 hours, and even more preferably for 1 to 1.2 hours.

[0111] If the initial activation time in the Steam atmosphere is less than 1 hour, the activation may be insufficient.

[0112] Conversely, if the primary activation time exceeds 3 hours, the continuous pore shape of the activated carbon collapses, and as these collapsed pores form mesopores, there is a problem in that mesopores are mainly formed.

[0113] Primary activation in a steam atmosphere can be performed at 700 to 1000°C, and preferably at 800 to 900°C.

[0114] If the primary activation temperature is less than 700℃, a sufficient specific surface area may not be formed.

[0115] Conversely, if the primary activation temperature exceeds 1000℃, the activation yield is lowered, and there is a disadvantage that the pore shape collapses due to overactivation, resulting in a lower specific surface area.

[0116] As described above, by primary activation in a steam atmosphere for 1 to 3 hours, 900 to 2000 m maintains the shape of continuous pores 2 It has the effect of forming a specific surface area of ​​ / g.

[0117] In addition, activation in a steam atmosphere does not require pH control and has a favorable effect in increasing the adsorption rate of harmful substances, and furthermore, can also demonstrate a carbon footprint reduction effect.

[0118] The pore size and structure change depending on the amount of steam injected.

[0119] In this regard, the amount of steam input during the first activation step may be 0.5 to 5 ml / min, and preferably 1.5 to 3.5 ml / min.

[0120] Satisfying a steam input amount of 0.5 to 5 ml / min is advantageous for controlling the size and structure of pores. Additionally, since the pore formation speed increases as the steam input amount of 0.5 to 5 ml / min increases, it may be difficult to control the formation of ultrafine pores after a certain level of specific surface area improvement, but this can be controlled by adjusting the primary activation time and secondary activation conditions.

[0121] The manufacturing temperature of the above steam may be 80 to 150°C, but is not limited thereto.

[0122] In the present invention, a CO2 gas atmosphere was selected as a secondary activation condition to maintain a high specific surface area of ​​activated carbon while simultaneously forming ultrafine pores of 1 nm or less.

[0123] Secondary activation in a CO2 gas atmosphere can be performed at a temperature range of 700 to 1000°C, similar to the temperature range of primary activation, and preferably at 800 to 900°C.

[0124] Activation in a CO2 gas atmosphere is favorable for forming ultrafine pores in activated carbon, and the pore formation rate and the rate at which pore shape collapses are relatively lower than those of activation in a steam atmosphere.

[0125] When carbonized raw materials are first activated in a steam atmosphere and then secondarily activated in a CO2 gas atmosphere, pore sizes of 1 nm or less can be mainly formed in the activated carbon, preferably pore sizes of 0.4 to 0.9 nm can be formed, and more preferably pore sizes of 0.4 to 0.7 nm can be formed.

[0126] The pore size of activated carbon can be measured using ISO 15901-2:2022, NLDFT method and equipment such as MicrotracBEL and BELSORP MAX models.

[0127] By complexly activating the carbonized raw material in a steam atmosphere followed by a CO2 gas atmosphere, the high specific surface area of ​​the activated carbon is maintained while forming ultrafine pores of a specific size of 1 nm or less, thereby further enhancing the adsorption capacity of the activated carbon.

[0128] Secondary activation in the above CO2 gas atmosphere can be performed for 1 to 2 hours, and preferably for 1 to 1.5 hours.

[0129] If the secondary activation is less than 1 hour, the activation of the carbonized raw material may be insufficient.

[0130] Conversely, if secondary activation exceeds 2 hours, the rate at which the generated micropores collapse is faster, which may lead to a decrease in micropore count.

[0131] In the second activation step, the amount of CO2 gas injected may be 0.05 to 10 slm (standard liter per minute, liters of CO2 gas injected per minute), preferably 0.1 to 5 slm, and more preferably 0.1 to 1 slm.

[0132] By satisfying the input amount of CO2 gas from 0.05 to 10 slm, there is an advantageous effect for forming ultrafine pores.

[0133] FIG. 3 is a schematic diagram showing the pore shape of a carbonized raw material according to the present invention, which is first activated in a steam atmosphere and then secondarily activated in a CO2 gas atmosphere.

[0134] As shown in Fig. 3, when carbonized raw materials are first activated in a steam atmosphere and then secondarily activated in a CO2 gas atmosphere, the activation speed in the steam atmosphere is faster, which is advantageous for forming a high specific surface area with a continuous pore shape, and subsequently, ultrafine pores (dotted line) can be formed while maintaining the high specific surface area.

[0135] Accordingly, in the present invention, activated carbon with a high micro-porosity can be produced by first activating the carbonized raw material in a steam atmosphere and then secondarily activating it in a CO2 gas atmosphere, and there is an effect of further reducing the activation time.

[0136] The manufacturing method of the present invention has the advantage of being able to produce activated carbon with a high specific surface area and ultrafine pores without using acidic or / and basic activators.

[0137] It can be confirmed that the activated carbon produced in the present invention has a low elemental content of the activator because acidic or / and basic activators are not used.

[0138] If chemical activation is performed using acidic activators including phosphoric acid (H3PO4) and sulfuric acid (H2SO4), a large amount of elemental content such as phosphorus (P) and sulfur (S) may be detected in the activated carbon.

[0139] When chemically activated with a basic activator including sodium hydroxide (NaOH) and potassium hydroxide (KOH), a large amount of elemental content such as sodium (Na) and potassium (K) can be detected in the activated carbon.

[0140] Since the activated carbon of the present invention is first activated in a steam atmosphere and then secondarily activated in a CO2 gas atmosphere, the content of elements detectable from acidic and basic activators is relatively lower than that of activated carbon produced through chemical activation.

[0141] In addition, the activated carbon of the present invention is found to have a relatively lower content of impurities, such as iron (Fe), compared to activated carbon produced through chemical activation.

[0142] When measuring the elemental content of the activated carbon of the present invention by ICP analysis, the elemental content of any one of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) may be 210 ppm or less, preferably 205 ppm or less, and more preferably 202 ppm or less.

[0143] Among the above elements, the elemental content of potassium (K) may be 210 ppm or less, preferably 205 ppm or less, and more preferably 202 ppm or less.

[0144] In addition, the elemental content of iron (Fe) may be 150 ppm or less, preferably 135 ppm or less, and more preferably 133 ppm or less.

[0145] The content of these elements can be confirmed through ICP (Inductively Coupled Plasma) analysis.

[0146] ICP analysis is a measurement method used to measure the concentration of various elements, including heavy metals. ICP analysis exhibits high sensitivity and precision and can analyze many metal elements simultaneously.

[0147] The activated carbon of the present invention is a porous activated carbon having a high specific surface area and includes ultrafine pores with a size of 1 nm or less.

[0148] Activated carbon is 900 ~ 2000m 2It can have a specific surface area of ​​ / g, preferably 1100 to 1800 m² 2 It can have a specific surface area of ​​ / g, and more preferably 1300 to 1800 m² 2 It can have a specific surface area of ​​ / g, and more preferably 1500 to 1700 m² 2 It can have a specific surface area of ​​ / g.

[0149] The specific surface area of ​​activated carbon is 900 to 2000 m² 2 By satisfying / g, there is a favorable effect in improving adsorption characteristics.

[0150] Activated carbon is characterized by a high ultrafine pore size of 1 nm or less. In this regard, activated carbon includes ultrafine pores of 1 nm or less and micropores greater than 1 nm and less than 2 nm, and among the total pores, the ultrafine pore size may be higher than the micropore size.

[0151] Ultrafine porosity can be calculated as (volume of ultrafine pores / volume of total pores) × 100%.

[0152] Activated carbon has the effect of further enhancing its adsorption capacity by maintaining a high specific surface area while possessing a high ultrafine porosity.

[0153] Specific examples of the method for manufacturing activated carbon with such ultrafine pores are as follows.

[0154] 1. Production of activated carbon

[0155] The specific surface area and pore results of the activated carbon in Figures 4 to 7 show the same results even when a carbonization step is performed between the compression molding step and the activation step.

[0156] Figure 4 shows the pore area (dV) according to the pore size (W / nm) of pores formed by activation in a steam atmosphere or a CO2 gas atmosphere to confirm the continuous pore distribution. p This is a graph showing / dW).

[0157] The sample used in Figure 4 is activated carbon produced by pre-treating and compression molding a bio-raw material, coconut shell, and activating it in a steam atmosphere or a CO2 gas atmosphere, respectively.

[0158] Figure 4 was measured using the ISO 15901-2:2022, NLDFT method and the MicrotracBEL, BELSORP MAX model equipment.

[0159] When manufacturing activated carbon, the size of pores that can be generated and the rate of pore formation vary depending on the type of activating gas.

[0160] The formation mechanism of micropores and mesopores is that pores that collapse during the creation of micropores become mesopores.

[0161] Referring to Fig. 4, as a result of activating the raw material in a steam atmosphere (0.5 ~ 5 ml / min) for 2 hours, pores larger than 1 nm were formed, and 1600 m 2 It showed a specific surface area of ​​ / g.

[0162] Compared to the sample activated for 2 hours in a CO2 gas atmosphere, the sample activated for 2 hours in a steam atmosphere had a higher specific surface area, so it can be seen that pores were formed quickly.

[0163] In addition, compared to the sample activated for 2 hours in a CO2 gas atmosphere, the sample activated for 2 hours in a steam atmosphere is faster in terms of activation speed and the rate at which micropores collapse faster than the rate at which micropores form, so it is determined that the rate of mesopore formation is faster.

[0164] On the other hand, the sample in which the raw material was activated in a CO2 gas atmosphere (0.05 ~ 10 slm) for 2 hours was 700 m 2 It exhibited a specific surface area of ​​ / g, and although the pore formation rate was slow, 0.4nm ultrafine pores were mainly formed.

[0165] From the results of Figure 4, it can be confirmed that there is a difference in the specific surface area generated in the steam atmosphere and the CO2 gas atmosphere, and that the formation rate of mesopores is faster in the steam atmosphere based on the pore distribution results.

[0166] A faster mesopore formation rate means that the rate of micropore collapse becomes faster than the rate of micropore formation.

[0167] FIG. 5 shows the volume (V) of adsorbed nitrogen according to the partial pressure (P / P0) of pores formed by activation in a steam atmosphere. a / cm 3 (STP) g -1 This is a graph showing ).

[0168] The sample used in Fig. 5 is activated carbon produced by pre-treating and compression molding a bio-raw material, coconut shell, raising the temperature to an activation temperature of 880°C in an Ar and N2 gas atmosphere, and activating it with steam generated at a temperature of 100°C or higher at an input amount of (0.5 to 5 ml / min).

[0169] Figure 5 was measured using the ISO 15901-2:2022, NLDFT method and the MicrotracBEL, BELSORP MAX model equipment.

[0170] The partial pressure on the X-axis (P / P0) represents the ratio of the (vapor) pressure at adsorption to the saturation (vapor) pressure.

[0171] Volume of adsorbed nitrogen on the Y-axis (V a / cm 3 (STP) g -1 ) refers to the volume of adsorbed gas (N2, He, etc.) per gram of solid material at standard conditions (STP; Standard Temperature & Pressure 0℃, 1 atm), and a large value indicates that the surface area of ​​the solid particle is large.

[0172] Referring to Figure 5, the specific surface area tended to decrease as the activation time of the steam atmosphere increased from 1 hour to 2 hours.

[0173] Specifically, activated carbon activated in a steam atmosphere for 1 to 1.5 hours has the largest specific surface area, and thereafter, a decrease in specific surface area can be observed at 2 hours.

[0174] Figure 6 shows the pore size (d) using the sample of Figure 5. p Pore ​​area (dV) according to / nm p / dd p This is a graph showing ).

[0175] When the raw material is activated in a steam atmosphere, the pores generated under the 1-hour activation condition are formed into pores with a size of 1 nm or less as the activation progresses to 1.5 hours, but it can be seen that they grow into pores with a size of 1 nm or more.

[0176] Eventually, it can be confirmed that the number of pores larger than 1.4 nm increases when the activation time reaches 2 hours.

[0177] Therefore, as the activation time increased from 1 hour to 2 hours, the continuous pore shape collapsed, the specific surface area no longer increased, and the pore size tended to increase.

[0178] For example, since activated carbon for supercapacitors tends to experience performance degradation if the pore size becomes too large, it is necessary to control the pore size when forming the specific surface area.

[0179] FIG. 7 shows the pore size (d) for Comparative Example 1 (1 hour in a steam atmosphere), Comparative Example 2 (6 hours in a CO2 gas atmosphere), and Example 1 (2.5 hours in a CO2 gas atmosphere after a steam atmosphere). p Pore ​​area (dV) according to / nm p / dd p This is a graph showing ).

[0180] The sample used in Fig. 7 is activated carbon produced by pre-treating and compression molding a bio-raw material, coconut shell, and activating it under the following three conditions in an Ar and N2 gas atmosphere.

[0181] Comparative Example 1, which is a steam atmosphere condition for 1 hour, is activated at 880°C for 1 hour with steam generated at a temperature of 100°C or higher at an input amount of 0.5 to 5 ml / min.

[0182] Comparative Example 2, which was under conditions of a CO2 gas atmosphere for 6 hours, was heated to an activation temperature of 880°C in an Ar gas atmosphere and activated for 6 hours in a CO2 gas atmosphere with an input amount of 0.1 slm (standard liter per minute, liters of CO2 gas input per minute).

[0183] Example 1, which is a condition of 2.5 hours in a CO2 gas atmosphere after a steam atmosphere, is a first activation for 1.5 hours using steam generated at a temperature of 100°C or higher at an input amount of (0.5 to 5 ml / min), followed by a second activation for 1 hour using a CO2 gas atmosphere with an input amount of 0.5 slm.

[0184] Referring to FIG. 7, Example 1 exhibits the largest specific surface area when activated in a steam atmosphere for 1.5 hours and primarily forms ultrafine pores when activated in a CO2 gas atmosphere for 1 hour, resulting in 1500 m² 2 The formation of mesopores could be inhibited in activated carbon having a specific surface area of ​​1 / g or more.

[0185] On the other hand, Comparative Example 1, in which the raw material was activated in a steam atmosphere for 1 hour, mainly formed pore sizes of around 1.4 nm and larger on the activated carbon.

[0186] Comparative Example 2, in which the raw material was activated in a CO2 gas atmosphere for 6 hours, had a slow activation rate, so it was necessary to activate it for 6 hours to obtain a high specific surface area on the activated carbon, and as the activation time increased, the number of pores with a size of 1.4 nm or larger increased.

[0187] Example 1, in which the raw material was activated in a CO2 gas atmosphere after a steam atmosphere, was sufficient to shorten the activation time and exhibit a specific surface area formed with ultrafine pores of a specific size on the activated carbon.

[0188] However, as confirmed above, activating the raw material in a CO2 gas atmosphere or a steam atmosphere was insufficient to produce these effects.

[0189] Table 1 shows the results of confirming the elemental content of products developed under different activation conditions using ICP analysis. The ppm unit means weight / weight.

[0190] The elemental content and specific surface area of ​​the developed product in Table 1 show the same results even when a carbonization step is performed between the compression molding step and the activation step.

[0191] [Table 1]

[0192]

[0193] Physically activated product (steam) manufacturing: Coal-based coke is pretreated and compression molded as a raw material, and activated in a steam atmosphere (0.5 ~ 5 ml / min) at 700 ~ 900℃ for 1 ~ 3 hours to produce activated carbon.

[0194] Chemically activated product (KOH) manufacturing: Coal-based coke is pretreated and compression molded as a raw material, and activated in a KOH atmosphere (KOH:raw material = 1:2 to 1:10 weight ratio) at 700 to 900°C for 1 to 3 hours to produce activated carbon.

[0195] Chemically activated products (KOH) are 1800–2200 m 2 It showed a specific surface area of ​​ / g.

[0196] Referring to Table 1, the physically activated product (steam) was activated in a steam atmosphere and showed an Fe content of 130 to 133 ppm and a K content of 200 to 202 ppm.

[0197] On the other hand, the chemically activated product (KOH) was activated with KOH, a basic activator, and showed an Fe content of 140 ppm or more and a K content of 600 ppm or more.

[0198] It can be confirmed that the K content of the chemically activated product (KOH) is more than 3 times greater than the K content of the physically activated product (steam).

[0199] From the results of Table 1, if the method of confirming elemental content through ICP analysis is used, it can be confirmed that the activated carbon of the present invention, having a high specific surface area and ultrafine pores, has an elemental content of potassium (K) and iron (Fe) of 210 ppm or less.

[0200] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. (a) a step of carbonizing the raw material; and (b) a step of activating the carbonized raw material to produce activated carbon; comprising, A method for manufacturing activated carbon in which the above-mentioned activation is performed by first activating the carbonized raw material in a steam atmosphere and then secondarily activating it in a CO2 gas atmosphere.

2. In Paragraph 1, Primary activation in the above steam atmosphere, 900 ~ 2000m 2 Method for manufacturing activated carbon forming a specific surface area of ​​ / g.

3. In Paragraph 1, A method for manufacturing activated carbon that forms a pore size of 1 nm or less by secondary activation in the above CO2 gas atmosphere.

4. In Paragraph 1, A method for manufacturing activated carbon in which primary activation in the above steam atmosphere is performed for 1 to 3 hours.

5. In Paragraph 1, A method for manufacturing activated carbon in which primary activation in a steam atmosphere and secondary activation in a CO2 gas atmosphere are performed at 700 to 1000℃.

6. In Paragraph 1, A method for manufacturing activated carbon in which secondary activation is performed in the above CO2 gas atmosphere for 1 to 2 hours.

7. In Paragraph 1, The above activated carbon is a method for manufacturing activated carbon containing continuous pores.

8. In Paragraph 1, A method for producing activated carbon in which the elemental content of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) is 210 ppm or less when the elemental content of the activated carbon is measured by ICP analysis.

9. In Paragraph 1, A method for manufacturing activated carbon comprising one or more of the above raw materials, including heavy tar, coal tar, coke, furan resin, sawdust, coconut shells, coffee grounds, bamboo, pruned wood, rice bran, kenaf, rice husk, malt residue, reed grass, coal-based pitch, petroleum-based pitch, anthracite, and green coke fine powder.

10. In Paragraph 1, The step of carbonizing the above (a) raw material is (a1) A step of pre-treating raw materials; and (a2) A method for manufacturing activated carbon comprising the step of compression molding the above-mentioned pretreated raw material and then carbonizing it.

11. In Paragraph 1, The above carbonization is performed in a reducing atmosphere at 700 to 900°C, and A method for producing activated carbon, wherein the above-mentioned reducing atmosphere is carried out in an inert gas atmosphere of one or more of nitrogen, argon, and hydrogen.

12. As porous activated carbon, It includes ultrafine pores with a size of 1 nm or less, and Activated carbon having an elemental content of phosphorus (P), sulfur (S), sodium (Na), potassium (K), or iron (Fe) of 210 ppm or less when elemental content is measured by ICP analysis.

13. In Paragraph 12, Activated carbon having an elemental content of potassium (K) of 210 ppm or less when elemental content is measured by ICP analysis.

14. In Paragraph 12, Activated carbon having an elemental iron (Fe) content of 150 ppm or less when elemental content is measured by ICP analysis.

15. In Paragraph 12, 900 ~ 2000m 2 Activated carbon having a specific surface area of ​​ / g.

16. In Paragraph 12, Activated carbon comprising ultrafine pores of 1 nm or less and micropores greater than 1 nm and less than or equal to 2 nm, wherein the ultrafine porosity among the total pores is higher than the microporosity.

17. In Paragraph 12, The above activated carbon is activated carbon containing continuous pores.

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