JPS6135284B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining activated carbon fibers from vegetable fibers, and more specifically, the present invention relates to a method for obtaining activated carbon fibers from vegetable fibers, and more specifically, carbonizes vegetable fibers, then supports zinc chloride on the carbonized product, and activates the carbonized fibers. The present invention relates to a method for producing activated carbon fibers with high flexibility.

Conventionally, cellulose fibers such as cotton and rayon are soaked in an aqueous solution of zinc chloride, dried, and then
A method is known in which activated carbon fibers are obtained by firing the fibers at 500 to 800°C, that is, by simultaneously performing both the carbonization and activation steps of the vegetable fibers. However, it has been found that the flexibility of activated carbon fibers obtained by this method is not necessarily sufficient.

In view of these circumstances, the inventors of the present invention have made extensive studies and found that a process of first carbonizing vegetable fibers, then supporting zinc chloride on the carbide, and activating it, that is, carbonizing the vegetable fibers. It has been found that extremely flexible activated carbon fibers can be obtained by dividing the process into two steps: first and activating the carbonized material. Based on this knowledge, the present inventors conducted further research and found that when vegetable fibers are preloaded with at least one selected from the group consisting of nitric acid, phosphoric acid, boric acid, and ammonium salts, activated carbon fibers can be adsorbed. It was found that performance also improved.

Furthermore, it has been found that the yield of activated carbon fibers increases dramatically when vegetable fibers are supported with phosphoric acid, boric acid, and ammonium salts.

Based on these findings, we have completed the present invention.

That is, the present invention is a method for producing activated carbon fibers, which is characterized by carbonizing vegetable fibers, then supporting zinc chloride on the carbonized product, and activating this.

The vegetable fiber used in the present invention refers to all fibers made from plants, such as flocked fibers (e.g. cotton, kapok, bamboo cotton,
panya, vegetable silk, etc.), bast fibers (e.g., flax, hemp, juite, ramie, kenaf, mitsumata, etc.), leaf vein fibers (e.g., Manila hemp, New Zealand hemp, sigil hemp, pita fiber, etc.), fruit fibers (e.g. ; coconut, etc.), others (e.g., straw, straw, seaweed sugamo fiber,
(irritability, etc.), such as viscose rayon,
Cellulose-based regenerated artificial fibers such as copper ammonia rayon, such as acetate and acetic acid sulphate, etc.
Examples include lurose-based semi-synthetic fibers. These fibers may be in the form of fibers, or may be formed into a fiber structure such as a woven fabric, a nonwoven fabric, or a felt paper.

In the present invention, first, the above-mentioned vegetable fibers are heated at about 250 to 450°C, preferably about 300 to 450°C, under an inert gas atmosphere.
At a temperature of 400℃ for about 0.25-2 hours, preferably about
Carbonize for 0.5-1 hour.

If the raw material fibers are supported with at least one selected from the group consisting of nitric acid, phosphoric acid, boric acid and ammonium salts before carbonizing the vegetable fibers, the flexibility of the carbide will be improved and the carbonization yield will be improved. The rate also increases significantly.

Here, examples of ammonium salts include ammonium salts of inorganic acids such as ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium phosphate, diammonium phosphate, ammonium borate, and ammonium phosphite, such as ammonium acetate, ammonium oxalate, and tartaric acid. Examples include ammonium salts of organic acids such as ammonium, but ammonium salts of inorganic acids are particularly preferred.

Examples of means for supporting the above-mentioned compound include means for immersing the raw material fiber in a solution containing the above-mentioned compound, or means for spraying a solution containing the above-mentioned compound onto the raw fiber. The concentration of a compound in a solution varies depending on the type of compound, but
For nitric acid, approximately 0.1-10% by weight, for phosphoric acid, approximately
It is preferred to use a solution of 0.1 to 10% by weight, for boric acid about 0.1 to 5% by weight, for ammonium salts about 1 to 30% by weight. The solution may be an aqueous solution or a solution containing alcohol or the like. The supported amount is approximately 0.1 to 5 parts by weight for nitric acid, approximately 0.5 to 5 parts by weight for phosphoric acid, and approximately 0.5 to 5 parts by weight for boric acid per 100 parts by weight of vegetable fiber.
5 parts by weight, preferably about 0.5 to 25 parts by weight in the case of ammonium salts. Carbonization conditions such as carbonization temperature and carbonization time may be the same as when these compounds are not supported.

Next, zinc chloride is supported on the carbide obtained as described above, and this is activated.

Examples of means for supporting zinc chloride include a method of preparing a zinc chloride solution and immersing the carbide in the solution, or a method of spraying the zinc chloride solution onto the carbide. Although the concentration of the zinc chloride solution varies depending on the type of carbide, it is preferably about 5 to 60% by weight, particularly about 10 to 50% by weight. For example, hydrochloric acid or alcohols may be added to the solution to increase the solubility of zinc chloride. The amount of zinc chloride supported is preferably about 30 to 200 parts by weight, particularly about 50 to 150 parts by weight, based on 100 parts by weight of the carbide. Activation is carried out, for example, by firing at a temperature of about 350 to 750° C. for about 0.25 to 2 hours in an atmosphere of combustion exhaust gas such as nitrogen, heavy oil, light oil, or kerosene.

The thus activated vegetable fibers may be washed and dried by conventional methods, if necessary.

The method of the present invention is easy to operate, has a high yield, and can stably obtain activated carbon fibers with excellent flexibility and adsorption power at a much lower cost than conventional methods, making it an extremely useful method industrially. It is.

EXAMPLES The present invention will be explained below using Examples.

Example 1 A commercially available cotton cloth (bleached) was wound around a 16-mesh stainless steel roll and placed in a silica glass tube.
Carbonization was carried out at a temperature of 350° C. for 0.5 hour in a nitrogen stream. After carbonization, the carbonization yield was examined after cooling to room temperature and found to be 21%. The carbide was immersed in an aqueous solution containing 20% by weight of zinc chloride and 1% by weight of hydrogen chloride for about 5 minutes, and then drained with a rubber roller to uniformly support zinc chloride. Loading amount is as zinc chloride
67g/100g - carbide. This was activated in a nitrogen stream at a temperature of 550°C for 0.5 hours.

After activation, the activated carbon fiber A was washed, purified, and dried to obtain highly flexible activated carbon fiber A with a yield of 15%. Regarding the activated carbon fiber A, the saturated adsorption amount of acetone at 25° C. was measured using air with an acene concentration of 37.5 g/m ³ and was found to be 21% by weight.

Example 2 A commercially available cotton cloth (bleached) was immersed in a previously prepared 3% by weight phosphoric acid aqueous solution for 5 minutes, and squeezed using a rubber roller to carry 3 g/100 g of phosphoric acid on the raw material cloth. The raw material cloth loaded with phosphoric acid was wound around a 16-mesh stainless steel wire mesh roll and placed in a nitrogen stream.
Carbonization was carried out at a temperature of 380°C for 1 hour. After cooling to room temperature, the carbonization yield was examined and found to be 35.6%. Applicable〓〓〓〓
Carbide was immersed in a solution containing 20% by weight of zinc chloride in the same manner as in Example 1 to obtain 70% zinc chloride.
g/100g - carbide zinc chloride was supported. Thereafter, activation was performed at 600° C. for 0.5 hours in the same manner as in Example 1. After washing, purification and drying, a good activated carbon fiber B was obtained. When the yield and acetone adsorption power of the activated carbon fiber B were measured, they were each 32%.
and 22%.

Example 3 A commercially available linen cloth was immersed in a previously prepared aqueous solution containing 3% by weight of boric acid for 3 minutes, and squeezed using a centrifuge to uniformly impregnate the raw cloth with boric acid (2.5g/100g). The chemical solution-impregnated cloth was carbonized in the same manner as in Example 1 at 350° C. for 0.75 hours. A solution containing 15% by weight of zinc chloride in the carbide was added as zinc chloride to 65g/
100g - Impregnated to form a carbide and heated at 550℃
Activated for 0.5 hours. Thereafter, the activated carbon fiber C was washed, purified, and dried to obtain a good activated carbon fiber C with a yield of 36%. The acetone adsorption power of the activated carbon fiber C was 19.8%.

Example 4 A commercially available linen cloth was immersed in a pre-prepared aqueous solution containing 15.5% by weight ammonium chloride for 3 minutes, and squeezed using a rubber roller to uniformly impregnate the raw cloth with ammonium chloride (22g/100g of ammonium chloride). Ta. The chemical solution-impregnated cloth was carbonized in the same manner as in Example 1 at 350° C. for 1 hour. A solution containing 40% by weight of zinc chloride in the carbide is converted to 120% by weight as zinc chloride.
g/100g - Impregnated to become carbide, 570℃
It was activated for 1 hour. Thereafter, the activated carbon fiber D was washed, purified, and dried to obtain a good activated carbon fiber D with a yield of 40%. The acetone adsorption power of the activated carbon fiber was 22%.

Example 5 A commercially available cotton cloth (bleached) was immersed in a previously prepared aqueous solution containing 20% by weight ammonium sulfate for 5 minutes.
The cloth was squeezed using a centrifuge and uniformly impregnated with ammonium sulfate at a ratio of 18 g/100 g of raw material cloth. The chemical solution-impregnated cloth was heated to 350°C in the same manner as in Example 1.
The mixture was carbonized for 1 hour. The carbide was impregnated with a solution containing 40% by weight of zinc chloride at a ratio of 118 g of zinc chloride/100 g of the carbide, and activated at 600° C. for 1 hour. Thereafter, the activated carbon fiber E was washed, purified, and dried to obtain a good activated carbon fiber E with a yield of 39.8%. The acetone adsorption power of the activated carbon fiber was 22.5%.

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Claims (1)

[Claims] 1. A method for producing activated carbon fibers, which comprises carbonizing vegetable fibers, then supporting zinc chloride on the carbonized product, and activating it. 2. Claim 1, wherein the vegetable fiber supports at least one selected from the group consisting of nitric acid, phosphoric acid, boric acid, and ammonium salts.
The method described in section.