JPH05339818A - Carbon fiber made by activated vapor phase - Google Patents

Abstract

PURPOSE:To obtain the fiber useful for various adsorbents and electronic materials by activating vapor phase carbon fiber obtained by a vapor phase decomposition. CONSTITUTION:Vapor phase carbon fiber obtained by a vapor phase decomposition is activated to obtain a highly pure activated carbon fiber having good crystallinity, a high electric conductivity and a narrow distribution range of pore size and excellent in uniformity of pore size, fiber diameter and aspect ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an activated vapor grown carbon fiber, and particularly to activated carbon obtained by activating a carbon fiber obtained by a vapor phase thermal decomposition reaction, which has excellent physical properties and various properties. A phase-related carbon fiber.

[0002]

2. Description of the Related Art Activated carbon obtained by activating various carbon materials has been used as an adsorbent or the like for a long time. Recently, polyacrylonitrile (PAN) -based and phenol-based carbon fibers have been surface-treated to control the pore size distribution and the introduction of various functional groups, which are used for high-performance adsorbents (molecular sieves) and electronic materials. Attempts have also been made to develop into technology. The high-performance adsorbent of activated carbon fiber is capable of exerting its selective adsorption function by pressure swing adsorption (Pressure Swing A).
(adsorption, PSA), organic solvent recovery, etc. In addition, electronic materials enable the realization of small and large capacity capacitors.

Such activated or functionalized carbon fiber is considered to be applied not only in the industrial and electronic fields but also in the field of biochemistry such as medical care (for example, dialysis) and other wide fields.

By the way, conventional activated carbon fibers are made by activating carbon fibers of cellulose type, polyvinyl alcohol type, polyacrylonitrile (PAN) type, phenol type, pitch type and the like. This fiber has an average pore size of 20 to 40 Å, but the pore size distribution region is 100
Å There is a wider distribution.

In addition, since the PAN-based carbon fiber before activation is manufactured at 1000 to 1500 ° C., the crystallinity is hardly developed and the electric conductivity is 10 ⁻⁴ Ω · c.
m is low. However, since the crystallinity is poor, when activated by containing a large amount of microcrystallites, oxygen-containing functional groups are easily introduced at the edges of the microcrystals, and a large amount of functional groups are present on the carbon fiber surface. There is.

On the other hand, carbon fibers made from pitch have a drawback that impurities in the pitch remain in the carbon fibers as they are.

[0007]

In recent years, development of a highly accurate separation system has been desired, and development of materials for an adsorbent used for separation has been actively pursued. Among them, carbon-based adsorbents have been attempted to develop into biochemistry by taking advantage of physical properties such as biocompatibility.

On the other hand, it has been attempted to develop into an electronic material by taking advantage of another physical property of carbon, that is, an electrical property.

However, in the conventional activated carbon fiber, as described above, the pore size distribution spreads to 100 Å or more, and a sharp distribution cannot be obtained. Therefore, it is not possible to selectively recognize and identify substances having different molecular sizes and shapes and efficiently separate them. It has a low electric conductivity, and the conductivity is not satisfied among the high surface area and high conductivity required for the polarizable electrode of the capacitor. However, the required characteristics could not be satisfied.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a highly activated carbon fiber which is useful as various adsorbents, electronic materials and the like.

[0011]

The activated vapor grown carbon fiber according to claim 1 is characterized in that the activated vapor grown carbon fiber obtained by the vapor pyrolysis reaction is activated.

The activated vapor grown carbon fiber according to a second aspect is the activated vapor grown carbon fiber having the following physical properties and characteristics.

Average pore size: 20-40Å Pore size distribution: 90% or more of the total pore size in the range of pore size 10-75Å Electric conductivity: 0.7-1.3 × 10 ^-3 Ω · cm Total oxygen concentration : 0.1m mol / g or less Raman spectrum intensity ratio: R = I ₁₃₆₀ / I ₁₅₈₀ = 0.7
5 to 0.96 Carbon content: 99% by weight or more Fiber diameter: 0.1 to 5.0 μm Aspect ratio: 50 to 5000 The present invention will be described in detail below.

In the present invention, a vapor grown carbon fiber obtained by a vapor pyrolysis method is used as a carbon fiber which is a raw material for activating the activated carbon fiber. The vapor grown carbon fiber can be easily produced, for example, by the method described in JP-A-63-92727.

Examples of the method for activating the vapor grown carbon fiber include the following methods.

[0016] Carbon dioxide (CO ₂ ), oxygen, air, propane combustion gas,
500 to 10 using steam, preferably CO ₂ gas
Heat treatment is performed at 00 ° C. for 30 minutes to 1 hour.

Plasma processing is carried out in a parallel plate type oxygen plasma.

By activating the vapor grown carbon fiber in this manner, a high-performance activated vapor grown carbon fiber having the above-mentioned physical properties and characteristics can be obtained.

In the above-mentioned physical properties and characteristics, the electric conductivity is a value that can be achieved without graphitization, and a low value of about 1 × 10 ⁻³ Ω · cm can be obtained.

The total oxygen concentration indicates the proportion of oxygen-containing functional groups such as ether groups, carbonyl groups, lactone groups and phenol groups existing on the surface.

The Raman spectrum intensity ratio indicates the surface crystal state. That is, 1 of Raman spectrum
Since the peak derived from 580 cm ^-1 is dependent on the graphite crystallites, the peak of 1360 cm ^-1 intensity I ₁₃₆₀ and 1580c
Ratio of intensity of peak at m ^-1 to I ₁₅₈₀ R = I ₁₃₆₀ / I
₁₅₈₀ is regarded as one index of crystallinity.

[0022]

[Function] By using the vapor grown carbon fiber as the carbon fiber as the activation raw material, the physical properties of the activated carbon fiber can be directly obtained as a structure having a fine uniform structure derived from the crystallinity of the vapor grown carbon fiber. A high-performance, high-performance activated vapor grown carbon fiber that greatly affects the properties is provided.

In particular, the vapor grown carbon fiber is difficult to introduce the oxygen-containing functional group even after the activation treatment, and the fine crystal structure is developed, so that the pore size distribution is in the range of 75 Å or less. When CO ₂ gas is used as the activating gas, the pore size distribution is obtained as a sharp peak in the range of 20 to 40 Å.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Example 1 A vapor grown carbon fiber was produced by the method described in JP-A-63-92727 under the following conditions. Laser: CO ₂ laser (10.591 μm) Raw material: C ₂ H ₄ Compound containing substance to be catalyst particles: Ferrocene Carrier gas: H ₂ Pressure: Normal pressure Residence time: 1 minute Raw material concentration: 5 vol% inH ₂ Reactor: 20 mm ID × 450 mm L (made of quartz) The obtained vapor grown carbon fiber was treated with CO ₂ gas (CO ₂ partial pressure: 10
(1.3 kPa) and activated at 1000 ° C. for 20 minutes to obtain an activated vapor grown carbon fiber of the present invention.

The Raman spectrum of the resulting activated vapor grown carbon fiber is shown in FIG. As apparent from FIG. 1, the peak is reflected in 1360 cm ^-1 and 1580 cm ^-1, R
= In I ₁₃₆₀ / I ₁₅₈₀ = 0.96, in the range of 0.75 to 0.96.

FIG. 2 shows the results of ESCA analysis of the oxygen-containing functional groups present on the surface of the activated vapor grown carbon fiber. As is clear from FIG. 2, ether, carbonyl,
Each functional group of lactone was introduced, but the total amount of oxygen was a very small amount of 0.05 to 0.1 mmol / g or less.

Further, the pore size distribution of the activated vapor grown carbon fiber is shown in FIG. As is clear from FIG. 3, the pore size is 10
It is distributed in the range of ~ 75Å, and there are sharp peaks particularly in the range of 20 ~ 40Å.

The electrical conductivity, carbon content, fiber diameter and aspect ratio of this activated vapor grown carbon fiber were examined and the results were as follows. Electric conductivity: 1.0 × 10 ⁻³ Ω · cm Fiber diameter: 0.5 to 1.0 μm Aspect ratio = 100 to 1000

[0030]

As described in detail above, according to the activated vapor grown carbon fiber of the present invention, the crystallinity is good, the electric conductivity is high, the pore size distribution range is narrow, and the pore size uniformity is excellent. Also, a highly pure activated carbon fiber having excellent uniformity in fiber diameter and aspect ratio is provided.

Such activated vapor grown carbon fiber is remarkably excellent in functionality and characteristics as an adsorbent, an electronic material and the like, and is industrially extremely useful.

[Brief description of drawings]

FIG. 1 is a diagram showing a Raman spectrum of activated vapor grown carbon fiber obtained in Example 1.

2 is E of the activated vapor grown carbon fiber obtained in Example 1. FIG.
It is a figure which shows a SCA analysis result.

FIG. 3 is a diagram showing the pore size distribution of the activated vapor grown carbon fiber obtained in Example 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location D01F 9/127 7199-3B D06M 10/00 11/76 // D06M 101: 40 7199-3B D06M 10 / 00 A

Claims (2)

[Claims] 1. An activated vapor grown carbon fiber obtained by activating a vapor grown carbon fiber obtained by a vapor decomposition reaction. 2. The activated vapor grown carbon fiber according to claim 1, which has the following physical properties and characteristics. Average pore size: 20-40Å Pore size distribution: Pore size in the range of 10-75Å is 90% or more of the total electric conductivity: 0.7-1.3 × 10 ⁻³ Ω · cm Total oxygen concentration: 0. Raman spectrum intensity ratio of 1 mmol / g or less: R = I ₁₃₆₀ / I ₁₅₈₀ = 0.7
5 to 0.96 Carbon content: 99% by weight or more Fiber diameter: 0.1 to 5.0 μm Aspect ratio: 50 to 5000