CN113135567B

CN113135567B - Preparation method of activated carbon and product thereof

Info

Publication number: CN113135567B
Application number: CN202110465242.8A
Authority: CN
Inventors: 王赫; 王洪杰; 胡程文; 曹叶
Original assignee: Anhui Polytechnic University
Current assignee: Anhui Polytechnic University
Priority date: 2021-04-28
Filing date: 2021-04-28
Publication date: 2022-03-18
Anticipated expiration: 2041-04-28
Also published as: CN113135567A

Abstract

The invention discloses a preparation method of activated carbon and a product thereof, belonging to the technical field of activated carbon preparation, wherein the preparation method comprises the following steps: adding a polyacrylonitrile precursor solution into water, separating out polyacrylonitrile pellets, stirring, washing, filtering, drying, soaking in an alkaline solution, drying again, and carbonizing to obtain the activated carbon; the activated carbon material prepared by using polyacrylonitrile as a carbon source material and an alkaline solution as an activating agent has a high specific surface area and a high porosity, and has a hierarchical porous structure which comprises micropores and mesopores; the method is simple and easy to implement and is suitable for popularization and application.

Description

Preparation method of activated carbon and product thereof

Technical Field

The invention belongs to the technical field of activated carbon preparation, and particularly relates to a preparation method of activated carbon and a product thereof.

Background

The activated carbon material is used as an excellent adsorbent and has a good adsorption effect on organic matters, inorganic matters and the like, so that the activated carbon material is widely applied to various fields such as water treatment, energy storage, solar seawater desalination, fuel cells and the like at present. The adsorption performance of the activated carbon has a direct relationship with the surface structure of the activated carbon, and the higher the porosity and the larger the specific surface area, the more excellent the adsorption performance. Moreover, researches find that the activated carbon material with the hierarchical pore distribution often shows better adsorption performance than the material with the single pore distribution, because different pores can correspondingly adsorb substances with different particle sizes in the material with the hierarchical pore distribution when the material with the hierarchical pore distribution is applied, the adsorption resistance can be reduced, and the better adsorption effect can be achieved. The active carbon material sold in the market at present is mainly obtained by carbonizing a carbon source material, and has low porosity and specific surface area and single pore size distribution, so that the adsorption performance of the active carbon material cannot meet the requirement of practical application.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation method of activated carbon and a product thereof.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a preparation method of activated carbon, which comprises the following steps: adding the polyacrylonitrile precursor solution into water, separating out polyacrylonitrile pellets, stirring, washing, filtering, drying, soaking in an alkaline solution, drying again, and carbonizing to obtain the activated carbon.

Further, the polyacrylonitrile precursor solution is a solution obtained by dissolving polyacrylonitrile in N, N-dimethylformamide and having a concentration of 5-12 wt%.

Further, the method also comprises the step of stirring for 12-24 hours at 25-60 ℃ before adding the polyacrylonitrile precursor solution into water.

Further, the polyacrylonitrile precursor solution is added into water at a speed of 1-5 mL/h.

Further, the washing is performed for 3-5 times by adopting absolute ethyl alcohol.

Furthermore, the drying temperature is 40-80 ℃, and the drying time is 12-24 hours.

Further, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution, the concentration is 1-4 mol/L, and the soaking time is 12-24 h.

Further, the carbonization is carried out in an inert gas atmosphere, the temperature is increased to 800-1200 ℃ at the speed of 3-5 ℃/min, and the temperature is kept for 1-2 h.

The invention also provides the activated carbon prepared by the preparation method.

Compared with the prior art, the invention has the following beneficial effects:

(1) the activated carbon material prepared by using polyacrylonitrile as a carbon source material and an alkaline solution as an activating agent has a high specific surface area and a high porosity, and has a hierarchical porous structure which comprises micropores and mesopores;

(2) the method is simple and easy to implement and is suitable for popularization and application.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is an SEM image of activated carbon prepared in example 1 at 20000 times magnification;

FIG. 2 is an SEM photograph of the activated carbon prepared in example 1 at 25000 magnification.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

Example 1

The preparation of the activated carbon comprises the following steps:

(1) preparing a polyacrylonitrile precursor solution with the concentration of 8 wt%, stirring at 40 ℃ for 18h, injecting into a 5mL needle tube, pushing at the speed of 3mL/h by adopting a propeller, collecting the pushed liquid in water, separating out white polyacrylonitrile pellets, and stirring simultaneously;

(2) washing the small balls in the step (1) for 4 times by using absolute ethyl alcohol, performing suction filtration, placing in a drying oven, and drying at 60 ℃ for 18 hours;

(3) and (3) taking out the polyacrylonitrile pellets dried in the step (2), putting the polyacrylonitrile pellets into a sodium hydroxide solution, fully soaking for 18h, drying at 60 ℃, putting the polyacrylonitrile pellets into a high-temperature tubular furnace for carbonization, adopting nitrogen for protection, heating to 1000 ℃ at the heating rate of 4 ℃/min, keeping the temperature for 1.5h, and taking out after the temperature is reduced to room temperature, thus obtaining the activated carbon.

The microstructure of the prepared activated carbon was observed using a scanning electron microscope, as shown in fig. 1 and 2, in which fig. 1 is a structural view at 20000 times magnification and fig. 2 is a structural view at 25000 times magnification.

Example 2

The preparation of the activated carbon comprises the following steps:

(1) preparing 5 wt% polyacrylonitrile precursor solution, stirring at 60 deg.C for 12h, injecting into 15mL needle tube, pushing at 1mL/h speed with a propeller, collecting the pushed liquid in water, separating out white polyacrylonitrile small balls, and stirring;

(2) washing the pellets in the step (1) for 3 times by using absolute ethyl alcohol, performing suction filtration, placing in an oven, and drying at 400 ℃ for 24 hours;

(3) and (3) taking out the polyacrylonitrile pellets dried in the step (2), putting the polyacrylonitrile pellets into a potassium hydroxide solution, fully soaking for 24h, drying at 40 ℃, putting the polyacrylonitrile pellets into a high-temperature tubular furnace for carbonization, adopting nitrogen for protection, heating to 800 ℃ at the heating rate of 3 ℃/min, keeping for 2h, and taking out after the temperature is reduced to room temperature to obtain the activated carbon.

Example 3

(1) Preparing 12 wt% polyacrylonitrile precursor solution, stirring at 25 deg.C for 24 hr, injecting into 20mL needle tube, pushing at 5mL/h speed by propeller, collecting the pushed liquid in water, separating out white polyacrylonitrile small balls, and stirring;

(2) washing the pellets in the step (1) for 5 times by using absolute ethyl alcohol, performing suction filtration, placing in an oven, and drying at 80 ℃ for 12 hours;

(3) and (3) taking out the polyacrylonitrile pellets dried in the step (2), putting the polyacrylonitrile pellets into a sodium hydroxide solution, fully soaking for 12h, drying at 80 ℃, putting the polyacrylonitrile pellets into a high-temperature tubular furnace for carbonization, adopting argon for protection, heating to 1200 ℃ at the heating rate of 5 ℃/min, keeping for 1h, and taking out after the temperature is reduced to room temperature to obtain the activated carbon.

Comparative example 1

The difference from example 1 is that step (1) is: preparing a polyacrylonitrile precursor solution with the concentration of 8 wt%, injecting the polyacrylonitrile precursor solution into a 5mL needle tube, pushing the polyacrylonitrile precursor solution at the speed of 3mL/h by adopting a propeller, collecting the pushed liquid in water, separating out white polyacrylonitrile balls, and stirring the polyacrylonitrile balls at the same time.

Comparative example 2

The difference from example 1 is that step (1) is: preparing a polyacrylonitrile precursor solution with the concentration of 8 wt%, stirring for 18h at 40 ℃, pouring the polyacrylonitrile precursor solution into water to separate out white polyacrylonitrile pellets, and stirring simultaneously.

Comparative example 3

The difference from example 1 is that "raising the temperature to 1000 ℃ at a temperature raising rate of 4 ℃/min" and holding for 1.5h "in step (3) is modified to" raising the temperature to 1000 ℃ at a temperature raising rate of 8 ℃/min "and holding for 1.5 h".

Comparative example 4

The difference from example 1 is that step (3) is: and (3) taking out the polyacrylonitrile pellets dried in the step (2), putting the polyacrylonitrile pellets into a high-temperature tube furnace for carbonization, adopting nitrogen for protection, heating to 1000 ℃ at the heating rate of 4 ℃/min, keeping the temperature for 1.5h, and taking out the polyacrylonitrile pellets after the temperature is reduced to room temperature to obtain the activated carbon.

Comparative example 5

The difference from example 1 is that the concentration of the sodium hydroxide solution in step (3) is 5 mol/L.

Effect verification

The specific surface area, porosity, and ratio of micropores to mesopores of the activated carbon materials prepared in examples 1 to 3 and comparative examples 1 to 5 were measured, and the results are shown in table 1.

TABLE 1

As can be seen from table 1, the activated carbon materials prepared in examples 1 to 3 have appropriate micropore and mesopore ratios, higher specific surface areas and higher porosities, and the specific surface areas and the porosities are significantly higher than those of the activated carbon materials prepared in comparative examples 1 to 5.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.

Claims

1. The preparation method of the activated carbon is characterized by comprising the following steps: stirring a polyacrylonitrile precursor solution at 25-60 ℃ for 12-24 h, then adding the polyacrylonitrile precursor solution into water at the speed of 1-5 mL/h, separating out polyacrylonitrile balls, stirring, washing, filtering, drying, soaking in a sodium hydroxide solution or a potassium hydroxide solution with the concentration of 1-4 mol/L for 12-24 h, drying again, and carbonizing to obtain the activated carbon;

and the carbonization is carried out in an inert gas atmosphere, the temperature is increased to 800-1200 ℃ at the speed of 3-5 ℃/min, and the temperature is kept for 1-2 h.

2. The preparation method according to claim 1, wherein the polyacrylonitrile precursor solution is a solution obtained by dissolving polyacrylonitrile in N, N-dimethylformamide and having a concentration of 5-12 wt%.

3. The preparation method according to claim 1, wherein the washing is performed 3 to 5 times with absolute ethyl alcohol.

4. The preparation method according to claim 1, wherein the drying temperature is 40-80 ℃ and the drying time is 12-24 hours.

5. An activated carbon prepared by the preparation method according to any one of claims 1 to 4.