CN106702538A - Preparation method of high-performance activated carbon fibers - Google Patents

Abstract

The invention discloses a preparation method of high-performance activated carbon fiber, which belongs to the technical field of carbon fiber. In the continuous activation equipment, polyacrylonitrile-based fibers are used as raw materials, the surface of the raw material fibers is first impregnated with chemical reagents, and then with the help of physical-chemical synergistic activation method, the water vapor volume fraction as a variable (regulation The value is in the range of 0.4×10 ^‑4 to 4.5×10 ^‑4 ) to prepare high-performance activated carbon fibers with a specific surface area of not less than 1500m ² .g ^‑1 and a tensile strength of not less than 0.5GPa. The method used in the invention is simple, the preparation efficiency is high, the cost is low, the obtained sample has a high specific surface area and excellent mechanical properties, and products of various shapes can be formed for the fields of gas purification, sewage treatment and the like.

Description

A kind of preparation method of high-performance activated carbon fiber

technical field

The invention relates to a preparation method of high-performance activated carbon fibers, belonging to the technical field of carbon fibers.

Background technique

Activated carbon fiber (ACFs for short) is a new type of high-efficiency adsorption material developed in the 1970s and gradually industrialized. Compared with traditional granular or powdered activated carbons, ACFs have unique properties: large specific surface area, high carbon content, narrow micropore distribution, large adsorption capacity, fast adsorption and desorption, easy regeneration; easy processing, and can be made into Fiber, paper, felt, cloth and other shapes; it has the characteristics of high strength, no pulverization, and no loosening or excessive compaction under vibration conditions. Therefore, the advent of ACFs has aroused great interest of scientists and entrepreneurs at home and abroad.

However, at present, ACFs products are usually prepared by using a single chemical reagent as an activator through a batch activation method. Although the final ACFs have a high specific surface area, the mechanical properties of ACFs samples prepared by this method are relatively low. It cannot be used to form products of various shapes, thereby limiting its application field. Therefore, it is of great significance to find a new activation method to ensure that the sample has a certain specific surface area and at the same time endow the ACFs sample with a certain mechanical strength. The present invention utilizes existing activation equipment to As a variable, a high-performance activated carbon fiber with a specific surface area of 1500-2550 m ² .g ^-1 and a tensile strength of 0.5-0.9 GPa is prepared by adopting an appropriate activation method.

Contents of the invention

Purpose of the present invention: aim at with existing activation equipment, with As a variable, by adopting an appropriate activation method to prepare ACFs products with high specific surface area and excellent mechanical properties, the problems of low preparation efficiency, low sample mechanical strength and high production cost in the preparation of existing adsorption materials are finally solved.

Another object of the present invention is to provide a high-performance activated carbon fiber application.

The object of the present invention is achieved by the following measures:

A method for preparing high-performance activated carbon fibers is characterized in that a single physical activation method or a physical-chemical synergistic activation method is used.

A method for preparing high-performance activated carbon fibers by a single physical activation method. The pre-oxidized carbon fibers are activated by continuous activation equipment, and water vapor and inert gas are passed into the equipment. The activation temperature is 700-900°C, preferably 800-875°C; activation time 10-40min, preferably 20-30min, Expressed as V _{water vapor} : (V _{water vapor} + V _{inert gas} ), controlled by adjusting the gas flow meter, The value is 0.4×10 ^-4 to 4.5×10 ^-4 ; the flow rate of V _{water vapor} corresponding to every 6.5L device is 1.04×10 ^-4 L.min ^-1 .

The method of preparing high-performance activated carbon fiber by physical-chemical synergistic activation method, impregnating the pre-oxidized carbon fiber into the activator solution, and then using continuous activation equipment to activate the fiber impregnated with the activator, and passing water vapor and inert gas into the equipment , the activation temperature is 700-900°C, preferably 800-875°C; the activation time is 10-40min, preferably 20-30min, Expressed as V _{water vapor} : (V _{water vapor} + V _{inert gas} ), controlled by adjusting the gas flow meter, The value is 0.4×10 ^-4 ～4.5×10 ^-4 ; the flow rate of V _{water vapor} corresponding to each 6.5L volume of equipment is 1.04×10 ^-4 L.min ^-1 . To achieve the purpose of promoting fiber activation. After the end, the obtained sample is washed repeatedly with distilled water, then boiled with distilled water, and finally washed repeatedly with distilled water until the solution after washing is neutral.

Preparation of pre-oxidized carbon fiber: Pre-oxidize the fiber raw material, the pre-oxidation temperature zone is (180-277°C), the pre-oxidation atmosphere is air atmosphere, and the total time for the fiber to stay in the pre-oxidation furnace is 50-80min.

The above-mentioned fiber raw materials are selected from polyacrylonitrile-based, pitch-based, viscose-based and phenolic-based fibers, and products in various forms such as felts, cloths, and belts formed from them. Among them, the polyacrylonitrile-based fiber can be spun by wet spinning method, dry spinning method or dry jet wet spinning method, and the fiber tow can be 1-320K;

The copolymer of one or more monomers with a mass fraction of less than 10% in polyacrylonitrile-based fibers is: itaconic acid, methyl acrylate, acrylic acid, allyl chloride, α-chloropropene, methacrylic acid, methyl methyl acrylate, hydroxyalkyl acrylonitrile, hydroxyalkyl acrylic acid and its esters, acrylamide, methacrylamide, diacetone acrylamide, methacryl acetone, etc. Especially when the above-mentioned different comonomers are added during the copolymerization of acrylonitrile, as long as the mass fraction of acrylonitrile monomer in the polyacrylonitrile precursor is higher than 90%, the present invention is applicable.

On existing activation equipment, with As a variable, high-performance activated carbon fibers with high specific surface area and excellent tensile strength were prepared by adopting an appropriate activation method. in, It can be expressed as V _{water vapor} : (V _{water vapor} + V _{inert gas} ), controlled by adjusting the gas flow meter, The value is 0.4×10 ^-4 to 4.5×10 ^-4 .

The activation equipment includes batch activation equipment and continuous activation equipment.

said variable It needs to be adjusted with the help of a gas flow meter.

The activator is selected from sodium hydroxide, potassium hydroxide, zinc chloride and K ₃ PO ₄ , and the mass percent concentration of the activator is 9-20%.

The activation method covers a single physical activation method and a physical-chemical synergistic activation method.

The active carbon fiber prepared by the invention has a specific surface area of 1500-2550m ² .g ^-1 and a tensile strength of 0.5-0.9GPa.

The principle of the present invention is: in the process of preparing high-performance activated carbon fibers using a single physical activation method and a physical-chemical synergistic activation method, the change of the gas flow in the system will affect the flow rate of the gas in the system. To affect the relevant properties of the final product.

The beneficial effect of the present invention is: with water vapor volume fraction As a variable to regulate the process of sample adsorption performance and mechanical properties, when When the value is in the range of 0.4×10 ^-4 to 4.5×10 ^-4 , the specific surface area of the product is 1500-2550m ² .g ^-1 , and the tensile strength is 0.5-0.9GPa. The obtained carbon fiber can be used in the fields of gas purification, sewage treatment and the like. At the same time, the method adopted in the present invention is simple, has high preparation efficiency and low cost.

Description of drawings

Fig. 1 is the curve that the specific surface area of the ACFs product prepared in Example 1 of the present invention changes with the water vapor volume fraction;

Fig. 2 is a curve of the single filament tensile strength of the ACFs product prepared in Example 1 of the present invention as a function of the water vapor volume fraction.

detailed description

The specific technical solutions of the present invention are further described below, so that those skilled in the art can further understand the present invention, without limiting their rights.

Embodiment 1: the preparation method of a kind of high-performance activated carbon fiber described in this embodiment is specifically carried out according to the following steps:

1. The 12K PAN precursor is pre-oxidized in a six-temperature zone continuous pre-oxidation furnace (the pre-oxidation temperature zone is 180-277 ° C), the pre-oxidation atmosphere is air atmosphere, and the total fiber stays in the pre-oxidation furnace The time is 70 minutes.

2. Using the pre-oxidized fiber obtained under the above conditions as a precursor, first impregnate the precursor fiber into a 9% KOH solution with a mass fraction, and then use continuous activation equipment (6.5 L in volume) to impregnate the impregnated activator The fiber was activated (activation temperature and activation time were 850°C and 20min, respectively). At the same time, nitrogen is used to transport water vapor from the outside to the activation furnace at a flow rate of 1.04×10 ^-4 L.min ^-1 , so as to achieve the purpose of promoting fiber activation by means of KOH+water vapor synergistic activation method.

3. By regulating the flow rate of nitrogen gas, the Sequentially adjusted to 0.4×10 ^-4 , 1.5×10 ^-4 , 2.5×10 ^-4 , 3.5×10 ^-4 and 4.5×10 ^-4 to prepare samples with different properties. After the experiment, the obtained samples were first used Wash it repeatedly with distilled water, then put it into a beaker for boiling, and finally wash it repeatedly with distilled water until the solution after washing is neutral.

Fourth, the obtained ACFs products were characterized in terms of relative adsorption performance and mechanical strength.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that in step 1, 24K PAN precursor is used as raw material, and the others are the same as Embodiment 1. The specific surface area of the ACFs product is 1450-2270m ² .g ^-1 , and the tensile strength is 0.7-1.0GPa.

Embodiment 3: The difference between this embodiment and specific embodiment 1 is that the pre-oxidation equipment used in step 1 is a continuous pre-oxidation furnace with four temperature zones, and the time for the fibers to stay in each temperature zone is 20min. Example 1 is the same. The specific surface areas of ACFs products are 1390m ² .g ^-1 , 1562m ² .g ^-1 , 1731m ² .g ^-1 , 1947m ² .g ^-1 and 2160m ² .g ^-1 respectively, and the corresponding monofilament tensile strength is 1.03GPa, 0.89GPa, 0.76GPa, 0.69GPa, and 0.74GPa.

Embodiment 4: The difference between this embodiment and Embodiment 1 is: the step 3 Adjusted to 0.27×10 ^-4 , 1.0×10 ^-4 , 1.67×10 ^-4 , 2.33×10 ^-4 and 3.0×10 ^-4 in turn, and the others are the same as in Example 1. The specific surface area of the ACFs product is 1153-2071m ² .g ^-1 , and the tensile strength is 0.8-1.1GPa.

Embodiment 5: The difference between this embodiment and Embodiments 1 to 4 is that the activation time of the sample in step 2 is 10 minutes, and the others are the same as Embodiment 1. The specific surface area of the ACFs product is 1021-1830m ² .g ^-1 , and the tensile strength is 0.7-1.2GPa.

Example 6: The difference between this embodiment and Examples 1 to 5 is that in step 2, K ₃ PO ₄ + steam synergistic activation method is adopted, and the mass fraction of K ₃ PO ₄ is 15%, Adjusted to 0.67×10 ^-4 , 2.5×10 ^-4 , 4.17×10 ^-4 , 5.83×10 ^-4 and 7.5×10 ^-4 in turn, and the others are the same as in Example 1. The specific surface areas of ACFs products are 702m ² .g ^{-1 , 820m 2 .g -1 , 897m 2 .g -1 , 961m 2 .g -1 and 1040m 2 .g -1} , and the corresponding monofilament tensile strength 1.24GPa, 1.07GPa, 0.93GPa, 0.89GPa and 0.81GPa.

Embodiment 7: The difference between this embodiment and the embodiment is that the mass fraction of K ₃ PO ₄ in step 2 is 9%, and the others are the same as in the embodiment 1. The specific surface area of the ACFs product is 670-980m ² .g ^-1 , and the tensile strength is 0.8-1.3GPa.

Embodiment 8: This embodiment is different from Embodiment 1 in that: in step 2, the mass fraction of K ₃ PO ₄ is 9%, the activation temperature is 900° C., and the others are the same as Embodiment 1. The specific surface area of the ACFs product is 755-1050m ² .g ^-1 , and the tensile strength is 0.7-1.2GPa.

Embodiment 9: The difference between this specific embodiment and the specific embodiment 1 is that a single steam activation method is adopted in step 2, Adjusted to 5.3×10 ^-4 , 20×10 ^-4 , 33.3×10 ^-4 , 46.7×10 ^-4 and 60×10 ^-4 in turn, and the others are the same as in Example 1. The specific surface areas of ACFs products are 450m ² .g ^-1 , 572m ² .g ^{-1 , 702m 2 .g -1 , 804m 2 .g -1 and 820m 2 .g -1 , and the corresponding monofilament tensile} strength is 1.30GPa, 1.22GPa, 1.01GPa, 0.86GPa, and 0.71GPa.

Embodiment 10: The difference between this specific embodiment and the specific embodiment 1 is that a single steam activation method is adopted in step 2, Adjusted to 8×10 ^-4 , 30×10 ^-4 , 50×10 ^-4 , 70×10 ^-4 and 90×10 ^-4 in turn, the activation temperature was 900°C, and the others were the same as in Example 1. The specific surface area of the ACFs product is 570-910m ² .g ^-1 , and the tensile strength is 0.6-1.1GPa.

Embodiment 11: The difference between this specific embodiment and specific embodiment 1 is that the inert gas used in step 3 is argon, and the others are the same as specific embodiment 1. The specific surface area of the ACFs product is 1530-2560m ² .g ^-1 , and the tensile strength is 0.6-0.8GPa.

Claims (6)

1. A preparation method for high-performance activated carbon fibers, characterized in that, a single physical activation method or a physical-chemical synergistic activation method is adopted; The method of preparing high-performance activated carbon fiber by a single physical activation method, the pre-oxidized carbon fiber is activated by continuous activation equipment, water vapor and inert gas are passed into the equipment, the activation temperature is 700-900 °C; the activation time is 10-40min, Expressed as V _{water vapor} : (V _{water vapor} + V _{inert gas} ), controlled by adjusting the gas flow meter, The value is 0.4×10 ^-4 ~ 4.5×10 ^-4 ; The method of preparing high-performance activated carbon fiber by physical-chemical synergistic activation method, impregnating the pre-oxidized carbon fiber into the activator solution, and then using continuous activation equipment to activate the fiber impregnated with the activator, and passing water vapor and inert gas into the equipment , the activation temperature is 700~900℃; the activation time is 10~40min, Expressed as V _{water vapor} : (V _{water vapor} + V _{inert gas} ), controlled by adjusting the gas flow meter, The value is 0.4×10 ^-4 ~ 4.5×10 ^-4 ; to achieve the purpose of promoting fiber activation with the help of activator + water vapor synergistic activation method; after the end, the obtained samples are washed repeatedly with distilled water, and then Boil with distilled water, and finally wash repeatedly with distilled water until the solution after washing is neutral. 2. The method according to claim 1, characterized in that the activation temperature of the single physical activation method or the physical-chemical synergistic activation method is 800-875° C., and the activation time is 20-30 minutes. 3. The method according to claim 1, characterized in that the flow rate of V _{water vapor} corresponding to a device with a volume of 6.5L per single physical activation method or physical-chemical coordinated activation method is 1.04×10 ^-4 L.min ^-1 . 4. according to the method for claim 1, it is characterized in that, the preparation of pre-oxidized carbon fiber: fiber raw material is carried out pre-oxidation, pre-oxidation temperature zone is 180～277 ℃, pre-oxidation atmosphere is air atmosphere, fiber is placed in pre-oxidation furnace The total time of residence is 50-80min. 5. according to the method for claim 4, it is characterized in that, fiber raw material is selected from polyacrylonitrile base, asphalt base, viscose base and phenolic base fiber, and the goods of various forms formed by them; Wherein, polyacrylonitrile The base fiber is spun by wet spinning method, dry spinning method or dry jet wet spinning method, and the fiber tow is 1-320K; Polyacrylonitrile-based fibers also contain one or more monomers with a mass fraction of less than 10% of the copolymers: itaconic acid, methyl acrylate, acrylic acid, allyl chloride, α-chloropropene, methacrylic acid , methyl methacrylate, hydroxyalkyl acrylonitrile, hydroxyalkyl acrylic acid and its esters, acrylamide, methacrylamide, diacetone acrylamide, methacryl acetone; especially when acrylonitrile is copolymerized with The different comonomers mentioned above. 6. The method according to claim 1, characterized in that the activator is selected from sodium hydroxide, potassium hydroxide, zinc chloride, K ₃ PO ₄ , and the mass percent concentration of the activator is 9-20%.