A method for preparing activated carbon fiber and activated carbon fiber prepared therefrom

Abstract

The present invention provides a method for preparing high-performance activated carbon fiber and the high-performance activated carbon fiber prepared by the method, belonging to the field of activated carbon fiber preparation. The preparation method comprises the following steps: impregnating a fiber raw material with a modifier, drying, and obtaining a modified fiber raw material; impregnating the obtained modified fiber raw material in a phosphoric acid solution, and drying; carbonizing the obtained product, washing with water, and drying. The obtained high-performance activated carbon fiber has no sticking and hardening problems, and the specific surface area can reach 2200m 2 / g or more, the product yield is not less than 40%, which solves the problem of excessive dissolution or hydrolysis damage to artificial fibers caused by high phosphoric acid loading rate.

Description

Technical Field

[0001] The invention relates to the field of activated carbon fiber preparation, and in particular to a method for preparing high-performance activated carbon fiber.

[0002] The present invention also relates to high-performance activated carbon fibers prepared by the above-mentioned preparation method of high-performance activated carbon fibers. Background Art

[0003] At present, the main method for preparing activated carbon fiber from artificial fibers in China is physical activation. The preparation process is that the artificial fiber (including viscose fiber, solvent-based cellulose fiber, cuprammonium fiber and other organic fibers) felt or cloth is impregnated with a certain concentration of phosphate solution and dried before carbonization and activation. Commonly used activators are water vapor and carbon dioxide.

[0004] This process has the following problems:

[0005] 1. Low product yield, specific surface area <1200m 2 / g ACF carbon yield <23%, specific surface area >1500m 2 / g ACF carbon yield is less than 16%, the higher the specific surface area, the lower the yield, and the production cost increases accordingly;

[0006] 2. The specific surface area of ​​the product is generally not more than 1800m 2 / g, otherwise the strength of ACF will deteriorate after deep activation, and powdering problems will occur, affecting the use of the product.

[0007] The phosphoric acid chemical activation method of artificial fibers can solve the above problems very well. When preparing activated carbon, the phosphoric acid chemical activation process can fully solidify the tar produced by the cellulose cracking process and convert it into a carbon component. In addition, this process does not form pores by ablating the carbon component under high temperature conditions of water vapor, so the product yield can reach more than 40%, and the product yield does not decrease with the increase of specific surface area, and the product yield can reach more than 40%.

[0008] However, this method also has problems. When the phosphoric acid loading rate exceeds 1:0.5 (man-made fiber: phosphoric acid), phosphoric acid's ability to dissolve and hydrolyze man-made fibers increases, causing the man-made fibers to pulverize, thereby destroying the fiber morphology, or causing the ACF to stick and harden during the carbonization stage, which greatly affects product application and reduces the yield rate. At low phosphoric acid loading rates, the ACF surface area prepared is less than 1100m 2 / g, has no market value. Summary of the invention

[0009] The purpose of the present invention is to provide a method for preparing activated carbon fiber. By modifying the fiber raw material, the problem of excessive dissolution or hydrolysis damage of artificial fiber caused by high phosphoric acid loading rate is solved, and the problem of adhesion and hardening in the process of preparing activated carbon fiber from artificial fiber is solved. The specific surface area of ​​activated carbon fiber can reach 2200m 2 / g or more, and the product yield is not less than 40%.

[0010] To achieve the above objectives, the present invention adopts the following specific technical solutions:

[0011] A method for preparing activated carbon fiber comprises the following steps:

[0012] S1: impregnating the fiber raw material with a modifier, drying and dehydrating to a constant weight, and obtaining a modified fiber raw material.

[0013] The fiber raw material includes paper, felt or cloth processed from artificial fibers and / or natural fibers;

[0014] Preferably, the man-made fiber includes one or more of viscose fiber, solvent-processed cellulose fiber or cuprammonium fiber, etc.; the natural fiber includes one or more of tencel fiber, cotton fiber or linen fiber, etc.

[0015] The modifier mainly includes a cross-linking agent; the cross-linking agent includes one or more of dialdehydes, polyvinyl alcohol, polyacrylamide or aziridine cross-linking agents, etc.; a single cross-linking agent is generally selected during use.

[0016] Preferably, the dialdehydes include one or more of formaldehyde, glutaraldehyde or succinaldehyde.

[0017] The mass ratio of the impregnated fiber raw material to the modifier is 1:0.001-0.02.

[0018] The drying is divided into primary drying and secondary drying.

[0019] Preferably, the temperature of the first drying is 100-140°C; the temperature of the second drying is 160-230°C. At the first drying temperature, the process of removing free water from the material is mainly completed, and the cross-linking reaction between the cross-linking agent and the cellulose molecules is promoted. At the second drying temperature, the fiber raw material partly undergoes keratinization, thereby obtaining better stability. However, at too high a temperature, keratinization will be excessive, affecting the penetration and diffusion of phosphoric acid in the next impregnation process.

[0020] Preferably, after the drying, triphosphoric acid is uniformly added to the product. Adding triphosphoric acid can both increase dehydration and yield in the later stage and prevent excessive cross-linking.

[0021] S2: The modified fiber raw material obtained in S1 is immersed in a phosphoric acid solution and dried.

[0022] Loaded phosphoric acid can play a catalytic and pore-forming role in the carbonization process. Too low a phosphoric acid concentration is not conducive to improving the loading rate and increases the drying energy consumption before carbonization. Too high a phosphoric acid concentration will lead to an increase in the unevenness of phosphoric acid loading.

[0023] Preferably, the concentration of the phosphoric acid is 15-40%;

[0024] Preferably, the temperature during the dipping is 10-25°C;

[0025] The impregnation amount is adjusted by the degree of pressing after the impregnation. Preferably, the impregnation loading ratio is fiber raw material: phosphoric acid = 1:0.6-1.1.

[0026] The moisture introduced during the impregnation process is removed by hot air drying.

[0027] S3: The product obtained in S2 is carbonized, washed with water, and dried to obtain the product.

[0028] The carbonization is carried out under the protection of an inert gas, the starting carbonization temperature of the carbonization is 140° C., and one or more of the following conditions are met:

[0029] (1) The carbonization is carried out by programmed temperature increase at a rate of 5-15°C / min;

[0030] (2) The maximum carbonization temperature of the carbonization is 350-550°C.

[0031] The drying is carried out by forced air drying at a temperature not exceeding 95° C. until the material reaches a constant weight.

[0032] The water washing is to wash with water until the pH value is neutral; and then drying to constant weight, and the drying temperature does not exceed 190°C.

[0033] The present invention also provides an activated carbon fiber prepared by the above-mentioned preparation method of the activated carbon fiber.

[0034] Compared with the traditional ACF production process of water vapor physical activation, the yield of the product in the ACF preparation process of the present invention is higher, and the yield can reach more than 40%. At the same time, compared with the existing phosphoric acid activation process, the present invention can improve the fiber's resistance to phosphoric acid dissolution by cross-linking and modifying the fiber raw material, increase the specific surface area of ​​the ACF product, and avoid the problem of powdering or sticking of the ACF during the carbonization process when the phosphoric acid load is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the background technology and embodiments of the present invention, the following briefly introduces the drawings required for use in the background technology and embodiments. It should be understood that the following drawings may only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 It is a schematic diagram of the process of preparing the activated carbon fiber in the present invention. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" and "several" mean two or more, unless otherwise clearly and specifically defined.

[0039] Example 1

[0040] A method for preparing activated carbon fiber, such as Figure 1 In the process shown, the viscose fiber felt is immersed in glutaraldehyde at a ratio of viscose fiber to glutaraldehyde = 1:0.5% at 20°C, and then dried once and twice. The primary drying temperature is 120°C, and the secondary drying temperature is 190°C.

[0041] The cross-linked modified viscose fiber felt was immersed in a 10% phosphoric acid solution at 20°C, with the impregnation ratio being phosphoric acid: viscose fiber = 1:0.95, and then dried at 90°C.

[0042] The dried product was heated to 450°C at 10°C / min in a nitrogen atmosphere to complete carbonization. The carbonized fiber was washed with water until neutral and dried to obtain the activated carbon fiber. The obtained activated carbon fiber was relatively soft, without sticking and hardening phenomenon, with an ACF yield of 45% and a specific surface area of ​​2297m 2 / g.

[0043] Example 2

[0044] A method for preparing activated carbon fiber comprises: impregnating viscose fiber felt in formaldehyde at a ratio of viscose fiber to formaldehyde = 1:0.8% at 20°C, and performing primary drying and secondary drying. The primary drying temperature is 107°C, and the secondary drying temperature is 220°C. After drying, triphosphoric acid is uniformly added to the product at a ratio of viscose fiber to triphosphoric acid = 1:0.05%.

[0045] The cross-linked modified viscose fiber felt was immersed in a 25% phosphoric acid solution at 20°C, with the impregnation ratio being phosphoric acid: viscose fiber = 1:0.8, and then dried at 70°C.

[0046] The dried product was heated to 400°C at 10°C / min in a nitrogen atmosphere to complete carbonization. The carbonized fiber was washed with water until neutral and dried to obtain the activated carbon fiber. The obtained activated carbon fiber was relatively soft, without sticking and hardening phenomenon, with an ACF yield of 48% and a specific surface area of ​​2365m 2 / g.

[0047] Example 3

[0048] A method for preparing activated carbon fiber comprises: impregnating viscose fiber felt in formaldehyde at a ratio of viscose fiber to formaldehyde = 1:0.1% at 20°C, and performing primary drying and secondary drying. The primary drying temperature is 107°C, and the secondary drying temperature is 220°C.

[0049] The cross-linked modified viscose fiber felt was immersed in a 25% phosphoric acid solution at 20°C, with the impregnation ratio being phosphoric acid: viscose fiber = 1:1, and then dried at 70°C.

[0050] The dried product was heated to 400°C at 10°C / min in a nitrogen atmosphere to complete carbonization. The carbonized fiber was washed with water until neutral and dried to obtain the activated carbon fiber. The obtained activated carbon fiber was relatively soft, without sticking and hardening phenomenon, with an ACF yield of 43% and a specific surface area of ​​2527m 2 / g.

[0051] Example 4

[0052] A method for preparing activated carbon fiber comprises: impregnating a solvent-processed cellulose fiber felt in succinaldehyde at a ratio of 1:0.1% of solvent-processed cellulose fiber and succinaldehyde at 20°C, and performing primary drying and secondary drying. The primary drying temperature is 140°C, and the secondary drying temperature is 180°C.

[0053] The cross-linked and modified solvent-processed cellulose fiber felt was immersed in a 35% phosphoric acid solution at 10°C, with the immersion ratio being phosphoric acid: solvent-processed cellulose fiber = 1:0.6, and then dried at 80°C.

[0054] The dried product was heated to 350°C at 15°C / min in a nitrogen atmosphere to complete carbonization. The carbonized fiber was washed with water until neutral and dried to obtain the activated carbon fiber. The obtained activated carbon fiber was relatively soft, without sticking and hardening phenomenon, with an ACF yield of 40% and a specific surface area of ​​2271m 2 / g.

[0055] Example 5

[0056] A method for preparing activated carbon fiber comprises: impregnating cuprammonia fiber felt in polyacrylamide at a ratio of cuprammonia fiber to polyacrylamide = 1:1% at 20°C, and performing primary drying and secondary drying. The primary drying temperature is 120°C, and the secondary drying temperature is 200°C.

[0057] The cross-linked modified cuprammonium fiber felt was immersed in a 15% phosphoric acid solution at 25°C, with the immersion ratio being phosphoric acid: cuprammonium fiber = 1:1.1, and then dried at 80°C.

[0058] The dried product was heated to 500°C at 10°C / min in a nitrogen atmosphere to complete carbonization. The carbonized fiber was washed with water until neutral and dried to obtain the activated carbon fiber. The obtained activated carbon fiber was relatively soft, without sticking and hardening phenomenon, with an ACF yield of 43% and a specific surface area of ​​2335m 2 / g.

[0059] In the description of this specification, the description with reference to the terms "one embodiment", "an example", "some examples", "preferred embodiments", "specific examples" and the like means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0060] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing activated carbon fiber, characterized in that: The steps of the preparation method are as follows: S1: impregnating the fiber raw material with a modifier, drying, and then evenly adding triphosphoric acid to the dried product to obtain a modified fiber raw material; S2: immersing the modified fiber raw material obtained in S1 in a phosphoric acid solution and drying; S3: carbonizing the product obtained in S2, washing it with water, and drying it to obtain the product; In S1: The modifier includes a cross-linking agent; The cross-linking agent includes one or more of dialdehydes, polyvinyl alcohol, polyacrylamide or aziridine cross-linking agents; the dialdehydes include glutaraldehyde or succinaldehyde; The drying is divided into primary drying and secondary drying; the temperature of the primary drying is 100-140°C; the temperature of the secondary drying is 160-230°C; The mass ratio of the impregnated fiber raw material to the modifier is 1:0.001-0.

02.

2. The preparation method according to claim 1, characterized in that: In S1, the fiber raw material includes paper, felt or cloth processed from artificial fibers and / or natural fibers; The man-made fibers include one or more of viscose fibers, solvent-processed cellulose fibers or cuprammonium fibers; the natural fibers include one or more of tencel fibers, cotton fibers or hemp fibers.

3. The preparation method according to claim 1, characterized in that: S2 satisfies one or more of the following conditions: a. the concentration of the phosphoric acid is 15-40%; b. The temperature during the dipping is 10-25°C; c. The loading ratio of the impregnation is fiber raw material: phosphoric acid = 1:0.6-1.

1.

4. The preparation method according to claim 1, characterized in that: The carbonization in S3 satisfies one or more of the following conditions: d. The heating rate of the carbonization is 5-15°C / min; e. The maximum carbonization temperature of the carbonization is 350-550°C.

5. The preparation method according to claim 1, characterized in that: In S3, the water washing is performed until the pH value is neutral; and the drying temperature does not exceed 190°C.

6. An activated carbon fiber, characterized in that Prepared by the preparation method according to any one of claims 1 to 5.

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