WO2012148037A1

WO2012148037A1 - Carbon grid shaped nanopore production method

Info

Publication number: WO2012148037A1
Application number: PCT/KR2011/003985
Authority: WO
Inventors: 김호; 최창식; 한기보; 장정희
Original assignee: 고등기술연구원 연구조합
Priority date: 2011-04-28
Filing date: 2011-05-31
Publication date: 2012-11-01
Also published as: KR101315112B1; JP2014516904A; KR20120121952A; JP5784822B2

Abstract

A carbon grid shaped nanopore production method comprises: a process wherein a precursor is prepared as a starting material; a stabilization process wherein the precursor is oxidised by being brought into contact with air; a carbonization process wherein the carbon form formed in the stabilization process is carbonized under oxygen-free conditions so as to form primary pores; a surface treatment process wherein the carbon form in which the primary pores have been formed is subjected to a surface treatment by being brought into contact with ozone; a dipping process wherein the carbon form which has been subjected to the surface treatment is dipped in an aqueous solution of an alkali metal; and a surface modification process wherein surface modification is carried out by inducing oxidation and reduction of the alkali metal while raising the temperature to no more than 800°C in an oxygen-free atmosphere. Also, the production method comprises a process in which, after the surface modification has been completed, cooling is carried out to room temperature under oxygen-free conditions and then dipping is effected for at least 1 hour in a sulfuric acid solution of no more than 5M, and cleaning is carried out in distilled water and then drying is carried out at about 150°C in the air.

Description

Manufacturing method of carbon lattice nano pores

The present invention relates to a method for producing carbon lattice nano-pores having a surface area of at least 2,500 m ² / g by developing fine pores of 3 nm or less in a carbon matrix material having pores.

Generally, carbon lattice materials having pores that are widely used include activated carbon (AC), activated carbon fiber (ACF), and the like. Conventionally, the carbon lattice material has a surface area of 1,000 to 1,500 m ² / g.

In the case of activated carbon, the size of the pores of 1 to 10 is broadly distributed from ⁵ nm range, there is the structure of the pore is a complex form, the size of the pore adsorption and desorption than the activated carbon fiber present at least 90% 3 nm or less, only There is a drawback that it is slow.

The structure, size and size distribution of pores of carbon lattice materials when adsorbing and desorbing hydrocarbons such as volatile organic compounds (VOCs) by carbon lattice materials are determined by adsorption amount and adsorption / desorption rate .

Generally, the carbon lattice material has a larger adsorption amount because the surface area increases as the number of micropores increases, and as the pore structure is simple and the pore size distribution is narrower, the adsorption / desorption rate is faster.

Therefore, as the micropores of uniform size are developed, the adsorption capacity is increased and at the same time, it is possible to secure a long-life adsorbent which is easy to repeatedly regenerate and desorb, and the recovery of the adsorbed material by repeated adsorption / There is an effect that it becomes easy.

FIG. 1 shows a conventional method of developing nano-sized micro pores on the surface of a carbon lattice having pores such as activated carbon and activated carbon fibers.

As shown in FIG. 1, the conventional micro pore manufacturing method includes a step (S10) of preparing a precursor using activated carbon as a starting material and a fibrous material as an activated carbon fiber, (S30) in which the carbon material formed in the stabilization process is carbonized in an oxygen-free condition at a temperature of 1,000 to 1,500 DEG C to form primary pores; ) And an activation process (S40) for further developing the first formed pores by injecting CO ₂ or steam in an oxygen-free condition at a temperature of 800 to 1,200 ° C. In a final process (S 50), the surface area Activated carbon or activated carbon fibers having a level of 1,500 m ² / g are produced.

Principle that pores are formed while being an oxidation process (hereinafter names as stabilization process) carbon body surface oxygen functional groups are formed on the (carbonyl group, carboxyl group, etc.) is brought into contact with the air pyrolysis at carbonization process, the hot partially gasified to CO ₂ And the pore is formed in the vacated space. Further, partial oxidation is further promoted by CO ₂ or steam during the activation process to further develop the pores.

In such a conventional method, there are two major difficulties in developing uniform micropores at high density.

First, there is a limit to increase the density of oxygen functional groups in the stabilization process. Second, it is difficult to control the rate of partial oxidation in the carbonization and activation process.

In the first difficulty, the lower the density of oxygen functional groups on the surface of the carbon lattice image, the lower the possibility of increasing the surface area since the number of pores becomes smaller due to insufficient pore development sites (i.e., defect sites).

Conventional methods utilize means for increasing the temperature by forming oxygen functional groups and controlling the density. However, the higher the temperature, the greater the loss of oxidation of the carbon body, and the temperature at the surface of the carbon lattice is not uniformly distributed, so that the formed oxygen functional group is also difficult to uniformly form on the surface of the carbon lattice.

When the distribution of oxygen functional groups is not uniform on the surface of the carbon lattice and is shifted to one side, the oxygen functional group formed in the next step of carbonization and activation process is not developed into nano pores and large pores are formed. It is impossible to produce a large surface area.

Secondly, it is difficult to precisely control the partial oxidation rate with the activation process of CO ₂ or steam injection in the temperature range of 800 ~ 1,200 ℃ under anaerobic condition.

An important aspect of the activation process is that the porosity must be partially oxidized only at the site of the oxygen functional group. When the peroxidation proceeds at the site of the oxygen functional group or the oxidation progresses at the other site, the pores are not developed and simply pyrolyzed, resulting in the reduction of the weight of the carbon body.

In addition, in the conventional method, the method of injecting CO ₂ or steam has an advantage in adjusting the partial oxidation rate, but it can be performed only at a high temperature of 800 ° C or more because of low oxidizing power, And the economical efficiency is lowered.

Accordingly, the present invention has been made to overcome the above-mentioned disadvantages. The object of the present invention is to solve the problems of the prior art, namely, ① low concentration and non-uniformity of oxygen functional groups in the stabilization process, and In order to solve the problem of temperature and long process time, surface treatment and surface modification are carried out in conjunction with the development of micropores of less than 3 nm on a carbon matrix material with pores to obtain a surface area of 2,500 m ² / g or more of carbon nanotubes.

In order to achieve the above-mentioned object, the present invention provides a method for producing a carbon lattice-like nano-pore, comprising the steps of: preparing a precursor as a starting material of a carbon lattice material; A carbonization step of carbonizing the carbon body formed in the stabilization step to form primary pores by carbonization under anaerobic conditions, and a step of forming a primary oxygen-functional group on the surface of the carbon lattice in a highly homogeneous manner A surface treatment process in which ozone is contacted to perform a surface treatment; and a step of immersing the carbon body subjected to the surface treatment in an aqueous solution of an alkali metal to bring the alkali metal into contact with the oxygen functional group formed by the ozone contact in the surface treatment process , And the surface of the carbon body subjected to the surface treatment in an oxygen-free atmosphere is heated to 800 DEG C or lower Comprises a surface modification step of the developed micropores and characters perform surface modification by inducing oxidation and reduction of the alkali metal.

The surface treatment may be carried out at a room temperature with ozone in a weight ratio of 0.2-0.7 g to the weight of 1 g of the carbon body.

In addition, the surface modification process can immerse the surface-treated carbon body in an aqueous solution of alkali metal having a concentration of 1 to 5M for 1 hour or more. At this time, Na or K is preferably used as the alkali metal.

In addition, the carbon lattice-phase nano pore manufacturing method of the present invention is characterized in that after completion of the surface modification process, the carbon material subjected to the surface modification treatment is cooled to an ordinary temperature under anoxic condition and then immersed in a sulfuric acid solution having a concentration of 5M or more for 1 hour or more And then washing with distilled water to neutralize the pH to 5 to 7, followed by drying at about 150 ° C in an air atmosphere, so that activated carbon or activated carbon fiber can be produced.

Also, in the stabilization process, the precursor is preferably oxidized at a temperature ranging from 200 to 300 ° C.

In the carbonization process, the carbon material is preferably carbonized at a temperature ranging from 900 to 1000 ° C.

In addition, the carbon lattice material may include activated carbon, and the precursor of the activated carbon preferably includes a wood-based material.

The carbon lattice material may include activated carbon fibers, and the precursor of the activated carbon fibers may include a fibrous material.

According to the present invention, the carbon lattice material produced by the conventional method has a surface area of 1,000 to 1,500 m ² / g, but when the surface treatment according to the present invention is performed in conjunction with the surface modification, the surface area of the carbon lattice material And more than 2,500 m ² / g.

Particularly, while the conventional carbonization temperature is lowered from 1,000 to 1,500 ° C. to 900 to 1,000 ° C. and the conventional activation temperature is reduced from 700 to 800 ° C. at 800 to 1,200 ° C., the conventional surface area of 1,000 to 1,500 m ² / g to 2,500 m ² / g or more.

In addition, the number of regeneration times in conventional regeneration conditions in which activated carbon or low-quality activated carbon fiber is desorbed at 120 DEG C after adsorbing hydrocarbons such as toluene to the destruction point is 70% of the initial adsorption amount at the conventional four- , Whereas the active and activated carbon fibers prepared according to the present invention retained more than 90% of the initial adsorption amount even when the number of regeneration was repeated 50 times or more.

Therefore, the nanocomposite carbonaceous adsorbent produced by the present invention can be produced at a lower temperature than the conventional method and can be used as a hydrocarbon treatment and recovery filter having high efficiency and long life Effect.

FIG. 1 is a process diagram showing a conventional method of manufacturing a carbon nanotube with a lattice structure.

FIG. 2 is a process diagram of a method for manufacturing a carbon lattice-like nano-pores according to a preferred embodiment of the present invention.

FIG. 2 shows a process for producing a carbon nanotube with carbon nanotubes according to a preferred embodiment of the present invention.

The carbon lattice-phase nanopore production method of the present invention is a method of developing nano-sized micropores in a carbon matrix material having pores.

Generally, carbon lattice materials having pores include activated carbon (AC), activated carbon fiber (ACF), and the like. Surface treatment (ST) and surface treatment Surface modification (Surface Activation, SA) can be linked to develop nano-sized pores to increase surface area and speed up adsorption and desorption. By increasing the surface area as described above, the amount of adsorbed to hydrocarbons in the air or in the water is increased, and the adsorption / desorption rate is rapidly exhibited, thereby improving the regeneration and recovery efficiency.

As shown in FIG. 2, the method for preparing a carbon lattice-like nano-pores according to the present invention includes a step (S100) of preparing a precursor as a starting material. When the carbon lattice material of the present invention is activated carbon, a wood-based material is used as the precursor, and when the carbon lattice material is activated carbon fiber, a fiber-based material is used as the precursor. The carbon lattice-phase nano-pore structure of the present invention may further comprise a stabilization step (S200) of oxidizing the precursor by bringing the precursor into contact with air at a temperature of 200 to 300 ° C (S200) A carbonization step (S300) of forming primary pores by carbonization in a temperature range of 900 ° C to 1,000 ° C; a step (S300) of forming carbon pores having a primary pore on the carbon lattice surface by forming a high- (S400) for performing a surface treatment, and a step of immersing the surface-treated carbon body in an aqueous solution of an alkali metal to bring the alkali metal into contact with the oxygen functional group formed by the ozone contact in the surface treatment process (S500); and heating the surface-treated carbon body in an oxygen-free atmosphere to 800 DEG C or less, (S600) for conducting surface activation to induce oxidation and reduction of metal to develop fine pores of 3 nm or less, and cooling the surface-modified carbon body to room temperature under anoxic condition, (S700) of drying at about 150 DEG C in an air atmosphere to uniformly develop fine pores having a size of 3 nm or less on the surface of the carbon lattice to obtain a surface area of not less than 2,500 m < ² > / g (S800). &Lt; tb >< / TABLE >

The contact of ozone in the surface treatment process is carried out for the purpose of forming a highly homogeneous oxygen functional group on the surface of the carbon lattice on the carbon body having unfilled pores for producing a carbon body, The surface treatment is performed by the pre-treatment concept. At this time, ozone can be contacted with 1 g of carbon body at room temperature and ozone in a weight ratio of 0.2 to 0.7 g or less.

In connection with this surface treatment process, for the purpose of developing fine pores of 3 nm or less by inducing oxidation and reduction of alkali metal while bringing an alkali metal into contact with an oxygen functional group formed by surface treatment and raising the temperature to 800 ° C or less in an oxygen- Surface modification is performed.

In the method of contacting the alkali metal, the surface treated carbon body is immersed in an aqueous solution of alkali metal of 1 to 5M concentration for 1 hour or more (at room temperature in 1-5 M solution), wherein the alkali metal is Na or K desirable.

Subsequently, the surface of the carbon body is immersed in an aqueous solution of an alkali metal, and the carbon body is dried in an air atmosphere at a temperature of 100 to 200 ° C. and maintained at an oxygen-free condition and a temperature of 600 to 800 ° C. for 1 hour or more.

After the completion of the surface modification process (S600), the substrate was cooled to room temperature under anaerobic conditions, immersed in a sulfuric acid solution having a concentration of 5M or less for 1 hour or more, washed with distilled water to neutralize the pH to 5 to 7, (S700) at about 150 < 0 > C.

As a result, in the final step (S800), activated carbon or activated carbon fiber having a large surface area at a surface area of 2,500 m ² / g can be produced.

Table 1 shows the detailed characteristics of the activated carbon fibers produced by the production method of the present invention in conjunction with the surface treatment and the surface modification as described above and the conventional activated carbon fibers having no pores.

[Table 1] Comparison of the surface area, adsorption capacity and regeneration capacity of the activated carbon fibers produced by the present invention and the activated carbon fibers prepared by the conventional method

* Condition for regeneration: 90% of initial adsorption amount is desorbed at 120 ℃

In Table 1, the adsorption amount of toluene was adsorbed at room temperature on the activated carbon fiber produced by the present invention and the activated carbon fiber prepared by the conventional method, and as a result, it was confirmed that the adsorption amount was increased in proportion to the increase of the surface area .

In addition, in the regeneration condition where desorption is carried out at 120 ° C after adsorption to the breakdown point, the number of regeneration times is reduced to 70% or less of the initial adsorption amount at the conventional four times level, It can be confirmed that the carbon fiber retains more than 90% of the initial adsorption amount even when the number of regeneration is repeated 50 times or more.

As described above, since the present invention is not limited to the above-described embodiments, the present invention can provide a nano- It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

Claims

As a method for producing a carbon lattice-phase nanopore,

Preparing a precursor as a starting material of the carbon lattice material,

A stabilization step of oxidizing the precursor in contact with air,

A carbonization step of carbonizing the carbon material formed in the stabilization step under oxygen-free conditions to form primary pores,

A surface treatment step of forming an oxygen functional group on the carbon lattice surface at a high concentration and homogeneously in the carbon body having the primary pore formed therein and contacting the ozone with the carbon lattice surface,

An immersion process in which the carbon body subjected to the surface treatment is immersed in an aqueous solution of an alkali metal to bring the alkali metal into contact with the oxygen functional group formed by the ozone contact in the surface treatment,

And a surface modification step of heating the carbon body subjected to the surface treatment in an oxygen-free atmosphere to 800 ° C or lower while inducing oxidation and reduction of the alkali metal to develop micropores, thereby performing surface modification

Carbon lattice phase nanopore.
The method according to claim 1,

Wherein the surface treatment is carried out by bringing the weight of 1 g of the carbon body into contact with ozone of 0.2 to 0.7 g or less at a room temperature,

Carbon lattice phase nanopore.
The method according to claim 1,

Wherein the surface modification step comprises immersing the surface-treated carbon body in an aqueous solution of an alkali metal having a concentration of 1 to 5M for 1 hour or more

Carbon lattice phase nanopore.
The method of claim 3,

Characterized in that Na or K is used as the alkali metal

Carbon lattice phase nanopore.
The method according to claim 1,

After completion of the surface modification process, the surface-modified carbon body is cooled to room temperature under anoxic condition, immersed in a sulfuric acid solution having a concentration of 5M or less for 1 hour or more, and neutralized with distilled water to a pH of 5 to 7 , And then drying at about 150 ° C in an air atmosphere

Carbon lattice phase nanopore.
The method according to claim 1,

Wherein the precursor is oxidized in a temperature range of 200 < 0 > C to 300 < 0 &

Carbon lattice phase nanopore.
The method according to claim 1,

Wherein the carbon material is carbonized in a temperature range of 900 ° C to 1000 ° C in the carbonization process

Carbon lattice phase nanopore.
The method according to claim 1,

Characterized in that the carbon lattice material comprises activated carbon and the precursor of activated carbon comprises a woody material

Carbon lattice phase or pore structure.
The method according to claim 1,

Wherein the carbon lattice material comprises activated carbon fibers and the precursor of the activated carbon fibers comprises a fibrous material

Carbon lattice phase or pore structure.