JPS61160423A - Production of activated carbon fiber from wood phenol - Google Patents

Abstract

PURPOSE:To obtain the titled activated carbon fiber having high absorptivity, by introducing a substituent group to hydroxyl group of wood to plasticize the wood, dissolving the plasticized wood together with a hardener in a phenolic compound, spinning the dope, hardening the fiber with heat, carbonizing and baking the fiber and activating with an oxidizing gas. CONSTITUTION:At least a part of hydroxyl groups of wood are substituted with one or more kinds of substituent groups (e.g. acetyl group) to obtain plasticized wood. The wood is dissolved in a phenolic compound, and a hardener (e.g. hexamethylenetetramine) is dissolved in the solution. The obtained solution is used as a spinning dope, and the spun fiber is hardened with heat to obtain wood phenol fiber. The fiber is optionally carbonized and baked in an inert gas atmosphere and activated with an oxidizing gas to obtain the objective activated carbon fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) There is currently a great desire to develop a more effective method of utilizing forest resources, which are renewable resources. In addition, in industries that use wood as raw materials, such as the pulp industry and the wood industry, there is an urgent need to establish methods for effectively utilizing wood waste.

Therefore, the present inventors discovered that wood with plastic properties can be dissolved in phenols through a simple chemical reaction, and as a result of considering the advanced utilization of this dissolved material,
We have invented a method for producing activated carbon fibers with sufficient adsorption capacity.

(Prior art) In order to make more advanced use of wood, we aim to make more advanced use of wood-based raw materials, including wood, by imparting plastic properties to wood through simple chemical reactions such as esterification or etherification. Attempts to do so have been proposed.

For example, JP-A-57-103804 and JP-A-56-1
No. 35552 discloses a technique for esterifying or etherifying wood (powder) in which organic groups have been introduced into some of the hydroxyl groups, and the plasticized wood thus obtained can be used as it is or with various synthetic polymer substances. It is described that the mixture is used as a molding raw material. Furthermore, JP-A No. 57-2360 discloses a technique for preparing a solution by dissolving plasticized wood obtained by introducing hydroxyl groups and esterifying or etherifying wood (wood flour) in an organic solvent. It is also described that the prepared solution can be molded into a film either alone or in co-dissolution with various synthetic polymers.

However, the above method has the disadvantage that spinnability and moldability are insufficient.

As a result of various improvements, the present inventors discovered a method for obtaining activated carbon fibers from wood phenolic fibers.

(Problems to be Solved by the Invention) The present invention provides a novel method for obtaining activated carbon fibers from wood phenolic fibers.

(Means for Solving the Problems) In the present invention, wood made into plastic by introducing at least one substituent into some or all of the hydroxyl groups is dissolved in phenol under heating conditions, and the dissolved solution is A curing agent is added thereto to form a spinning solution. The spinning solution is discharged into the air from a spinneret and cured under heating conditions to produce wood phenolic fibers, which are carbonized and fired and then activated to produce activated carbon fibers.

The raw materials for the production of plasticized wood are wood-pulverized pulp, mechanical pulp or partially or completely delignified pulp. Further, there is no restriction on the type of wood used as a raw material, and the method of the present invention can be applied to any type of wood. The plasticization modification reaction of the present invention in which substituents are introduced into wood raw materials is a reaction in which substituents are introduced into at least some of the hydroxyl groups of cellulose, hemicellulose, or lignin present in the wood raw materials, for example, one of the hydroxyl groups. This is a reaction to esterify or etherify the moiety. Esterification and etherification reactions are preferred as such plastic modification reactions.

Modifiers used for esterification and etherification include free acids, acids and their derivatives such as acid halides and acid anhydrides, and halides such as alkyl halides and ethylene chlorohydrin. Preferred examples of the substituent introduced by the plasticization modification reaction include an a7tyl group, a propionyl group, and a butyryl group.

Valeroyl group, aliphatic acyl group, benzoyl group and other aromatic acyl groups, methyl group, ethyl group.

Examples include lower alkyl groups such as. It is also possible to introduce two or more of these substituents.

The introduction ratio of substituents differs depending on the type of substituent, but in general, in order to obtain modified wood with good organic solvent solubility, the substitution ratio expressed as substituent morality is 75%.
The above is desirable.

Here, "substituent morality" means 1000g of wood7')
It refers to the number of moles of substituents introduced by substitution.

Plastic modification treatment can be carried out according to known techniques. Generally, powdered wood may be treated with a modifier in the presence of an organic solvent or a swelling agent at room temperature or under heating conditions. Thoroughly wash the wood to be modified. For example, it is poured into methanol, filtered, and washed with water or methanol. Then dry.

The dried plastic wood is then dissolved in phenolics.

A part of this technology for dissolving plasticized wood into phenols was reported at the 32nd Wood Science Society Meeting (1982). Phenols is a general term for compounds in which the hydrogen atom bonded to the benzene ring is replaced with a hydroxyl group.
Phenol, 0-cresol, m-cresol, p-cresol, 3.5-xylenol, 2.3-xylenol, 2.4-xylenol, 2.5-xylenol, 2
, 6-xylenol, 3,4-xylenol, and the like. It may also be a mixture of the above phenols.

The melting device is a container with a cooler or a pressurized container. The melting temperature is 100-350℃, and the melting time is 15
It takes from about minutes to several hours. The dissolved concentration of plasticized wood ranges from several centimeters to 80% by weight, and to exceed 25%, it is necessary to uniformly mix the plasticized wood and phenols with a device such as a kneader before melting.

Furthermore, an organic solvent may be added during mixing to achieve more uniform mixing. They are chloroform, acetone, methylene chloride, methanol, ethanol, etc.

Examples of the curing agent include hexamethylenetetramine alone, or a combination of aldehydes such as formaldehyde, paraformaldehyde, and furfural with catalysts such as ammonia, amines such as trimethylamine and triethylamine, pyridine, or urea.

Next is the spinning process. When the curing agent is hexamethylenetetramine, add 6-6% of the above solution to 1 part (weight) of hexamethylenetetramine.
A spinning solution is obtained by mixing 40 parts of the solution and completely dissolving it.The mixing temperature is 70 to 90°C.Alternatively, add aldehydes to the above solution and blow ammonia etc. into the spinning solution. The mixed spinning solution was introduced into an extruder equipped with a spinneret, and after heating to 100-150°C for 6-10 minutes,
The yarn is discharged into the air from a spinneret, and the discharged yarn is wound up by a winder.

The wound uncured discharge yarn is subsequently subjected to a curing treatment.

The curing method may be heating in air, and the curing temperature is 150℃.
-300°C, preferably 180-250°C.

The rate of temperature increase from room temperature is 10 to 60°C/min, and may be lower than that.

Uncured fibers made of 100% phenol melt before reaching the curing temperature and lose their fiber shape.

On the other hand, wood phenol fibers reach the curing temperature without melting, and can be cured while maintaining the fiber form.

When carbonizing and firing hardened wood phenolic fibers, there is no need for conventional infusibility treatment steps such as those for rayon-based, PAN-based, or pitch-based fibers, or for carbonizing and firing the fibers under tension. It is possible to carry out carbonization firing in an active gas atmosphere under no tension or under tension.

Nitrogen, helium, etc. can be used as the inert gas, and the temperature increase rate may normally be 1°C/min to 50°/min.

The carbonization firing temperature is 400 to 1500°C. The treatment time and treatment temperature for carbonization firing are appropriately determined depending on the required adsorption power.

The fibers carbonized and fired in this way improve their ability to adsorb substances dissolved or dispersed in gases and liquids.
Perform activation processing.

The activation step may be performed on the wood phenolic fibers as they are cured.

The activation treatment is performed in an oxidizing gas. Preferably, steam, carbon dioxide, oxygen, air, combustion gas, etc. are used alone or in combination.

The activation time and temperature are determined by the required adsorption performance and are influenced by the type of activation gas.

Usually, it is carried out at a temperature of 600 to 1200°C for several minutes to several hours.

When activating wood phenolic fibers that have not been carbonized and are still cured, relatively mild conditions of 300 to 700°C are preferred.

Further, the fibers before being activated by the gas may be pretreated with zinc chloride, phosphoric acid, a phosphoric acid compound, potassium sulfide, or the like.

Example 1 After drying, 6 g of Radiata pine refiner ground pulp (RGP) is weighed and placed in a reactor.

A mixed solution of 114 mmol of trifluoroacetic anhydride and 120 mmol of acetic acid, which had been aged in advance at 50°C for 60 minutes, was placed in the above reactor, the temperature was set at 50°C, and the mixture was allowed to react for 2 hours. After the reaction is completed, the reaction solution is dispersed in 151 methanol to decompose excess acylating reagent, and then dried. The substituent morality of the obtained modified wood was 12.6.

50 parts (by weight) of the modified wood thus obtained and 50 parts (by weight) of phenol were placed in a Nigu, and at a temperature of 60°C approximately 1
Mix up the time. The mixed sample is placed in a reactor equipped with a reflux device and refluxed at 200 to 220°C for 6 hours to obtain a completely dissolved mixture. 1 part (by weight) of hexamethylenetetramine was added to 8 parts (by weight) of the solution, and 9
Stir at 0°C to dissolve hexamethylenetetramine.

The solution is used as a spinning solution. The spinning solution is put into a spinning machine heated to 150'C, left for 5 minutes, and then extruded into the air through a circular spinneret (pore diameter: 0.5 mm). The extruded filament was then stretched and wound up to a diameter of 40 μm.

The rolled uncured wood phenolic fiber was transferred to a furnace and heated from room temperature to 250°C at a rate of 20°C/min.
Hold for 60 minutes to complete curing.

Note that the atmosphere inside the furnace was air. The obtained wood phenolic fiber has a tensile strength of 17kli'/++t+7 and an elongation of 1
It was 2chi.

This wood phenolic fiber was treated with a nitrogen flow of 200116/mi.
Placed in an electric furnace with n atmosphere and heated at a rate of 5.5 without tension.
Carbonization firing was performed by raising the temperature to 700°C at a rate of °C/min. The thus obtained carbonized and fired fibers were held at 700° C. for 15 minutes for activation in a nitrogen stream containing 5.01 volumes of oxygen gas. Yield at activation is 391%
Met. The decolorizing power of methylene blue was determined according to JIS K1470, and the result was 150 ml/g, which was equivalent to that of commercially available powdered activated carbon. The tensile strength of the wood phenolic activated carbon fiber is 35.3 kg/-.

Example 2 A radiata pine thermomechanical valve (TMP) is weighed out at 100 I after drying and placed in a reactor. A mixture of 1.2 moles of acetic anhydride and 12.0 moles of acetic acid was put into the above reactor, and -
Leave at room temperature day and night. After that, further acetic anhydride 5.0
mol, 12.5 mol of acetic acid and 0.0 mol of perchloric acid as a catalyst.
A 2 mol mixture was added and reacted at 45° C. for 6 hours. After the reaction was completed, the mixture was neutralized with 0.015 mol of potassium carbonate, washed with deionized water, and dried. The resulting modified wood has a morality of 12.1.

40 parts (by weight) of the modified wood thus obtained and 60 parts (by weight) of phenol were placed in a kneader and mixed at a temperature of 50°C for 1 hour. The mixed sample is placed in a pressurized container and heated at 250° C. for 6 hours to obtain a completely dissolved mixture. Add 1 part of hexamethylenetetramine (by weight) to 6 parts (by weight) of the mixed solution.
weight) and completely dissolved by stirring at 120°C to obtain a spinning solution, put the spinning solution into a spinning machine at 150°C, extrude it into the air through a circular spinneret (pore diameter 0.5 mm),
Subsequently, it was stretched and wound up. The diameter of the wound filament is 30
I was born with μ. The uncured wood phenolic fibers are introduced into a furnace in an air atmosphere and left at 250° C. for 60 minutes to complete the curing process. This wood phenolic fiber has a tensile strength of 16.
The weight was 5 kg/xi and the elongation was 13%.

The wood phenolic fibers were introduced into an electric furnace with a nitrogen flow of 150 ml/min, and the temperature was raised at a rate of 5.5°C under no tension.
Carbonization and firing are carried out by raising the temperature to 700°C at /min.

The carbonized and fired fiber thus obtained was activated in a nitrogen stream containing about 25% water vapor. The activation temperature was set at 700° C. and maintained for 40 minutes to obtain wood phenol activated carbon fibers with an activation yield of 490%.

The methylene blue decolorizing power was determined in accordance with JIS K1470 and showed a value of 2'+01rLt19, which was sufficient to have the ability of commercially available powdered activated carbon. The tensile strength of this wood phenolic activated carbon fiber was 38.0 kg/mj.

Example 3 Tensile strength 1 after curing treatment was completed in the same manner as in Example
Wood phenolic fibers with 6.5 kll/ysd and an elongation of 13 cm were introduced into an electric furnace with a nitrogen flow of 200 m1/min, and heated to 80 °C at a temperature increase rate of 6.0 °C/min under no tension.
Carbonization firing was performed by raising the temperature to 0°C.

The carbonized and fired fibers were activated at an activation temperature of 700° C. for 65 minutes in a nitrogen stream containing 25 grams of water vapor. The yield upon activation was 62.0%, and the decolorizing power of methylene blue was determined according to JIS K1470, and it was 250ml.
/'j, and the unadsorbed performance was 1100 m9/g according to JIS K 1474, indicating that it had sufficient adsorption capacity.

Claims (1)

[Claims] Dissolving wood made into plastic by introducing at least one substituent into some or all of the hydroxyl groups in phenols, and further adding and dissolving a hardening agent,
After spinning this solution as a spinning solution, it is heated and cured to produce wood phenolic fibers, and the thus obtained wood phenolic fibers are carbonized and fired as they are or in an inert gas atmosphere, and then activated with an oxidizing gas. A method for producing wood phenolic activated carbon fiber, characterized by: