Preparation method of activated carbon with high iodine value and high specific surface area

Abstract

The invention provides a preparation method of activated carbon with a high iodine value and a high specific surface area, and belongs to the technical field of coal-based activated carbon. According to the method, a KOH and water vapor physical and chemical activation method is adopted, and the alkali-carbon ratio is reduced to 1.5: 1 by introducing water vapor to assist activation, so that the problems of over-high economic cost and equipment corrosion caused by over-high alkali-carbon ratio in an existing activated carbon preparation method are solved. In the application, when only KOH is used as the activating agent, the specific surface area of the activated carbon prepared under the condition that the alkali-carbon ratio is 1.5: 1 reaches 1034.1 cm < 2 > / g, and the iodine adsorption value reaches 1427.2 mg / g. When KOH and K2CO3 mixture is used as an activating agent, KOH is partially replaced by K2CO3, the alkali-carbon ratio is kept at 1.5: 1, and the specific surface area of the activated carbon prepared under the condition that the alkali composition is KOH: K2CO3 = 5: 1 reaches 1214.3 cm < 2 > / g, and the iodine adsorption value reaches 1578.4 mg / g. And a mixture of KOH and K2CO3 is used as an activating agent, so that the use of KOH is further reduced, the corrosion to instruments and equipment is reduced, the method is environment-friendly, and the production cost is saved.

Description

Technical Field

[0001] This invention relates to the field of coal-based activated carbon technology, specifically to a method for preparing activated carbon with high iodine value and high specific surface area. Background Technology

[0002] In existing technologies, the chemical activation method is a common process for preparing coal-based activated carbon. This method typically involves thoroughly mixing and impregnating coal-based raw materials (such as anthracite, bituminous coal, or their derivatives) with a strongly alkaline chemical activator (such as KOH). Subsequently, the mixture is subjected to a one-step pyrolysis activation reaction in a relatively low temperature range (450-700℃) under an inert atmosphere (such as nitrogen or argon protection). During this process, the activator KOH acts as a strong dehydrating agent, inhibiting tar formation; it also acts as an etchant, efficiently reacting with amorphous carbon to "sculpt" a well-developed porous structure; and it also has template and catalytic effects, ultimately forming activated carbon with a high specific surface area.

[0003] However, to obtain an extremely high specific surface area and ideal pore structure, the mass ratio of activator to coal feedstock is usually higher than 3:1. An excessively high alkali-to-carbon ratio not only increases product costs but also causes serious damage to equipment.

[0004] In view of this, it is necessary to design an improved method for preparing activated carbon to solve the above problems. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a method for preparing activated carbon with high iodine value and high specific surface area, aiming to solve the problems of excessive economic cost and equipment corrosion caused by excessively high alkali-to-carbon ratio in existing activated carbon preparation methods.

[0006] In a first aspect, embodiments of this application provide a method for preparing high-iodine-value, high-specific-surface-area activated carbon, comprising the following steps: mixing raw coal, an activator, and water, stirring magnetically in an oil bath at 30-60°C, allowing to stand for 4-12 hours, and then drying; grinding the dried mixture into fine powder and placing it in a tube furnace for carbonization under nitrogen protection; subsequently, introducing steam into the tube furnace and activating it at 750-850°C for 1.5-2 hours, soaking it in 4% hydrochloric acid at 100°C, filtering it, and then washing it with deionized water until neutral and drying it to obtain high-iodine-value, high-specific-surface-area activated carbon; wherein, the activator is KOH or a mixture of KOH and K2CO3.

[0007] Furthermore, the activator is KOH, and the mass ratio of KOH to raw coal is (0.5-1.5):1.

[0008] Furthermore, the activator is a mixture of KOH and K2CO3, and the mass ratio of the KOH and K2CO3 mixture to the raw coal is (0.5-1.5):1.

[0009] Furthermore, in the KOH and K2CO3 mixture, the mass ratio of KOH to K2CO3 is (4-5):(1-2).

[0010] Furthermore, during the carbonization process, the carbonization temperature is 450℃-550℃, and the carbonization time is 55-65 minutes.

[0011] Furthermore, when raw coal, activator, and water are mixed, the ratio of raw coal: activator: water is 4g: (2-6)g: (5-10)ml.

[0012] This application provides a method for preparing activated carbon with high iodine value and high specific surface area. This method employs a physicochemical activation method using KOH and steam. By introducing steam to assist activation, the alkali-to-carbon ratio is reduced to 1.5:1, solving the problems of excessively high economic costs and equipment corrosion caused by excessively high alkali-to-carbon ratios in existing activated carbon preparation methods. In this application, when using only KOH as the activating agent, the activated carbon prepared at an alkali-to-carbon ratio of 1.5:1 achieves a specific surface area of ​​1034.1 cm². 2 / g, with an iodine adsorption value of 1427.2mg / g.

[0013] Furthermore, when using a mixture of KOH and K₂CO₃ as the activator, this application partially replaces KOH with K₂CO₃, maintaining an alkali-to-carbon ratio of 1.5:1. Specifically, the activated carbon prepared under the alkali composition of KOH:K₂CO₃ = 5:1 achieves a specific surface area of ​​1214.3 cm⁻¹. 2 The iodine adsorption value reached 1578.4 mg / g. Using a mixture of KOH and K₂CO₃ as the activator further reduced the use of KOH, decreased corrosion of instruments and equipment, was environmentally friendly, and further saved production costs, resulting in activated carbon with high iodine value and high specific surface area.

[0014] That is, by using the method of this application, when the alkali-to-carbon ratio is 1.5:1, the iodine adsorption value and specific surface area of ​​the activated carbon can reach the level of the traditional method when the alkali-to-carbon ratio is 4:1. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0016] Figure 1 This is a schematic flowchart of the preparation method of the high iodine value and high specific surface area activated carbon of this application.

[0017] Figure 2 The image shows the nitrogen adsorption-desorption isotherm of the activated carbon (AC) prepared in Example 1.

[0018] Figure 3 The image shows the aperture distribution of the AC obtained in Example 1.

[0019] Figure 4 The image shows the SEM image of AC obtained in Example 4; where (a) is magnified 5000 times and (b) is magnified 20000 times.

[0020] Figure 5 The image shows the nitrogen adsorption-desorption isotherm of AC prepared in Example 4.

[0021] Figure 6 The image shows the pore size distribution of the AC obtained in Example 4.

[0022] Figure 7 This is a comparison chart of the iodine values ​​of AC prepared in Examples 1-3 and Comparative Examples 1-3.

[0023] Figure 8 The iodine adsorption values ​​and yields of AC prepared in Examples 1, 4-6 are shown. Detailed Implementation

[0024] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0026] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0027] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0028] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0029] In the traditional method of producing activated carbon from coal using KOH, the amount of activator KOH used is usually more than three times that of coal (the alkali-to-carbon ratio is too high), which leads to problems such as large KOH usage, strong corrosiveness to instruments, and high cost.

[0030] Please refer to Figure 1 As shown, this application provides a method for preparing high-iodine-value, high-specific-surface-area activated carbon, comprising the following steps: mixing raw coal, activator, and water, stirring magnetically in an oil bath at 30-60℃, letting stand for 4-12 hours, and drying; grinding the dried mixture into fine powder and placing it in a tube furnace for carbonization under nitrogen protection; subsequently, introducing steam into the tube furnace and activating at 750-850℃ for 1.5-2 hours, soaking in 4% hydrochloric acid at 100℃, filtering, and then washing with deionized water until neutral and drying to obtain high-iodine-value, high-specific-surface-area activated carbon; wherein, the activator is KOH or a mixture of KOH and K2CO3, and the mass ratio of the activator to the raw coal is (0.5-1.5):1.

[0031] When the activator is a mixture of KOH and K2CO3, the mass ratio of KOH to K2CO3 in the mixture is (4-5):(1-2).

[0032] During carbonization, the carbonization temperature is 450℃-550℃ and the carbonization time is 55-65 minutes.

[0033] When raw coal, activator and water are mixed, the ratio of raw coal: activator: water is 4g: (2-6)g: (5-10)ml.

[0034] In this application, by using a combination of physicochemical activation method and KOH-K2CO3 composite activator, the alkali-to-carbon ratio can be reduced, the amount of KOH used can be significantly reduced, the wear and tear on raw coal and instruments can be reduced, and the cost can be greatly reduced. It also produces high-quality activated carbon with better adsorption performance.

[0035] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0036] Example 1 Example 1 provides a method for preparing activated carbon with high iodine value and high specific surface area. The specific implementation steps are as follows: Place 4g of raw coal and 6g of KOH in a beaker, add 5ml of water, stir magnetically in an oil bath at 60℃, and let stand for 12 hours. Then, grind the dried mixture into fine powder, transfer it to a boat, place it in a connected tube furnace, seal the tube furnace, and introduce nitrogen gas into it as a protective gas.

[0037] Under nitrogen protection, the carbonization temperature is raised to 450℃-550℃ and carbonized for 60 minutes. Then, water vapor is introduced into the tube furnace and activated in the activation furnace at 750℃ for 1.5 hours. After soaking in 4% hydrochloric acid at 100℃ for 2 hours, the carbon is filtered out and washed with deionized water to obtain activated carbon with high iodine value and high specific surface area.

[0038] Example 2-3 Compared with Example 1, the main difference is that the amount of KOH was changed, as shown in Table 1. Other experimental parameters and conditions are basically the same as those in Example 1, and will not be repeated here.

[0039] Figure 2 The nitrogen adsorption-desorption isotherm of the activated carbon prepared in Example 1 shows that the activated carbon exhibits a composite of I and IV.

[0040] Figure 3 This is a pore size distribution diagram of the activated carbon prepared in Example 1. It can be seen that the activated carbon is mainly composed of micropores.

[0041] Example 4 Compared with Example 1, the main difference is that 6g KOH is replaced with 5g KOH and 1g K2CO3, as shown in Table 1. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0042] Figure 4The image shows an SEM image of the activated carbon prepared in Example 4. As can be seen, the prepared activated carbon has a rich pore structure.

[0043] Figure 5 The nitrogen adsorption-desorption isotherm of the activated carbon prepared in Example 4 shows that the activated carbon exhibits a composite of I and IV.

[0044] Figure 6 This is a pore size distribution diagram of the activated carbon prepared in Example 4. As can be seen, the prepared activated carbon is mainly composed of micropores.

[0045] Example 5 Compared with Example 1, the main difference is that 6g KOH is replaced with 4g KOH and 2g K2CO3, as shown in Table 1. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0046] Example 6 Compared with Example 1, the main difference is that 6g KOH is replaced with 3g KOH and 3g K2CO3, as shown in Table 1. Other experimental parameters and conditions are basically the same as in Example 1, and will not be repeated here.

[0047] Table 1 Summary of process parameter data for Examples 1-6 Comparative Example 1 Comparative Example 1 provides a traditional method for preparing activated carbon, in which steam is not introduced into the tubular furnace after carbonization; the specific implementation steps are as follows: 4g of raw coal and 16g of KOH were placed in a beaker, and 10ml of water was added. The mixture was magnetically stirred in an oil bath at 60℃ and allowed to stand for 12 hours. The dried mixture was then ground into a fine powder and transferred to a boat, which was placed in a connected tube furnace. The tube furnace was sealed, and nitrogen gas was introduced as a protective gas. Under nitrogen protection, the temperature was raised to the carbonization temperature of 450℃-550℃ for 60 minutes, followed by activation in an activation furnace at 750℃ for 1.5 hours. The activated carbon was then soaked in 4% hydrochloric acid at 100℃ for 2 hours, filtered out, and washed with deionized water to obtain activated carbon.

[0048] Comparative Examples 2-3 Compared with Comparative Example 1, the main difference is that the amount of KOH was changed, as shown in Table 2. Other experimental parameters and conditions are basically the same as those in Comparative Example 1, and will not be repeated here.

[0049] The activated carbon prepared was analyzed using a static liquid nitrogen adsorption method with an ASAP2020 fully automated pore size distribution analyzer. The data are as follows: Figure 7 , Figure 8 As shown in Table 2.

[0050] Table 2. Performance comparison of activated carbons prepared in Examples 1-6 and Comparative Examples 1-3 Comparing Examples 1-3 with Comparative Examples 1-3, it can be seen that the physicochemical activation method can reduce the alkali-to-carbon ratio to achieve the same effect as traditional chemical activation.

[0051] Comparing Examples 1 and 4, it can be seen that the activated carbon prepared by introducing potassium carbonate as an auxiliary agent on the basis of physicochemical activation has better performance than the activated carbon prepared by pure KOH physicochemical activation.

[0052] Examples 7-11 Compared with Example 4, the main difference is that the oil bath process parameters and activation process parameters were changed, as shown in Table 3. Other experimental parameters and conditions are basically the same as those in Example 4, and will not be repeated here.

[0053] Table 3 Summary of experimental data from Examples 4 and 7-11 The activated carbons prepared in Examples 7-11 were subjected to performance tests, and the results are shown in Table 4.

[0054] Table 4 Performance data of activated carbon obtained in Examples 7-11 As shown in Table 4, activated carbon with high iodine value and high specific surface area can be successfully prepared in Examples 7-11.

[0055] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for producing a high-iodine-value high-specific-surface-area activated carbon, characterized by, The process comprises the following steps: mixing raw coal, activating agent and water, and then placing the mixture in an oil bath for magnetic stirring at 30-60 DEG C for 4-12 hours, and then drying; grinding the dried mixture into fine powder, and then placing the powder into a tube furnace for carbonization under nitrogen protection; then, water vapor is introduced into the tube furnace, and the mixture is activated at 750-850 DEG C for 1.5-2 hours, and then soaked in 4% hydrochloric acid at 100 DEG C, and then filtered, and then washed with deionized water until neutral, and then dried, thereby obtaining activated carbon with high iodine value and high specific surface area; wherein the activating agent is KOH or a mixture of KOH and K2CO3.

2. The method of producing a high-iodine-value high-specific-surface-area activated carbon according to claim 1, characterized by, The activating agent is KOH, and the mass ratio of KOH to raw coal is (0.5-1.5):

1.

3. The method of producing a high-iodine-value high-specific-surface-area activated carbon according to claim 1, characterized by, The activating agent is a mixture of KOH and K2CO3, and the mass ratio of the mixture of KOH and K2CO3 to raw coal is (0.5-1.5):

1.

4. The method of producing a high-iodine-value high-specific-surface-area activated carbon according to claim 3, characterized by, In the mixture of KOH and K2CO3, the mass ratio of KOH to K2CO3 is (4-5):(1-2).

5. The method of producing a high-iodine-value high-specific-surface-area activated carbon according to claim 1, characterized by, During the carbonization treatment, the carbonization temperature is 450-550 DEG C, and the carbonization time is 55-65 minutes.

6. The method of producing a high-iodine-value high-specific-surface-area activated carbon according to claim 1, characterized by, During the mixing of raw coal, activating agent and water, the mass ratio of raw coal to activating agent to water is 4g:(2-6)g:(5-10)ml. During the carbonization treatment, the carbonization temperature is 450-550 DEG C, and the carbonization time is 55-65 minutes.

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