TWI773263B - Method for producing porous carbon - Google Patents

Abstract

The present invention relates to a method for producing porous carbon, including: a carbon raw material being placed in a carbonization space and carbonized at a carbonization temperature ranged from 250℃ to 800℃ for 0.5 to 16 hours; the carbon raw material being placed in an activation space and activated by adding 0.3 to 1920 liters of activation gas into the activation space at an activation temperature ranged from 440℃ to 550℃ for at least 60 minutes, thereby being processed to form a porous carbon material. Compared with the carbon raw material, the porous carbon material has larger surface area and is applicable to technical fields such as gas storage and energy storage.

Description

Porous carbon manufacturing method

The present invention relates to an activated carbon manufacturing method which can increase the specific surface area.

General activated carbon needs to be activated to produce activated carbon with high porosity and high specific surface area, and can use its strong adsorption capacity to adsorb substances. The activation treatment can be divided into physical activation method and chemical activation method. The physical activation method uses carbon dioxide or water vapor as an activator to heat the system to a high temperature, so that the carbon in the carbon material becomes carbon dioxide and escapes, leaving holes on the surface, but this activation method will cause a large amount of carbon material. Losses reduce yield. The chemical activation method is to use potassium hydroxide, sodium hydroxide, zinc chloride, phosphoric acid and other chemicals to directly react the carbon material with the chemicals. Chemicals have the disadvantage of polluting the environment.

Therefore, there is a patent case of Invention No. I687371 "Manufacturing Method of Activated Carbon for Electrode Materials" announced on March 11, 109 of the Republic of China, which mainly includes: heat treatment of activated carbon materials in an environment including chlorine-containing gas step, wherein, in the activated carbon material after the step of performing heat treatment, the content of metal impurities is 0.1 ppm to 20 ppm or less. And the step of activating the carbonized carbon material mixed with the activator can be performed at an activation temperature of 500°C or more; 500°C to 1200°C; 500°C to 1000°C; or 600°C to 800°C. When included in this temperature range, it is possible to provide activated carbon with a large specific surface area, good formation of micropores, etc., avoiding the problem of particle size increase due to activated carbon coagulation, and excellent crystallinity. However, the previous case of the patent will cause energy consumption due to the need to use high temperature activation.

Another paper "Mesopore-dominated hollow carbon nanoparticles prepared by simple air oxidation of carbon black for high mass loading supercapacitors" published on April 30, 2020. Although the paper discloses that there is a technology for burning carbon in air using a temperature below 550 degrees. However, it only discloses the use of carbon black as the raw material of the carbon material, and does not disclose other materials as the raw material of the carbon material. Moreover, the prepared activated carbon can only reach a specific surface area of about 750 m ² /g, but cannot reach 3000 m ² /g, so it is obviously different from the technical characteristics of the present invention.

In this regard, in view of the above-mentioned shortcomings in the activation treatment of activated carbon at present. Therefore, the present invention provides a method for producing porous carbon, which includes: performing a carbonization treatment on a carbon material raw material, placing the carbon material raw material into a carbonization space for carbonization treatment; placing the carbon material raw material in an activated carbon material An activation treatment is carried out in the space, and an activation gas is added. The addition amount of the activation gas is 0.3 to 1920 liters. The activation temperature during the activation treatment is 400 to 550 ° C, and the activation time is 30 to 960 minutes. Thereby, a porous carbon material is made.

The source of the above carbon material raw material is waste tire carbon, waste plastic, biomass, wood chips, coffee grounds, rice straw, bagasse, pitch, carbon black, graphite, graphene, carbon tube or any combination thereof.

The above-mentioned carbon materials are made of waste tire carbon, wood chips, coffee grounds, rice straw or bagasse, and need to be purified first. The treatment temperature is 25 to 100°C, and the treatment time is 0.5 to 16 hours.

The components of the acidic solution are hydrochloric acid, sulfuric acid or nitric acid, and the components of the alkaline solution are potassium hydroxide or sodium hydroxide.

The above carbonization space is a carbonization furnace, and the activation space is an activation furnace.

The above-mentioned activation gas system is oxygen and/or air, the addition amount of the oxygen is 0.3 to 1920 liters, the addition amount of the air is 0.3 to 1920 liters, the activation temperature is 450 to 550 ℃, and the activation time is 90 to 90 300 minutes.

When using the oxygen or the air for the above activation treatment, an additional activation auxiliary gas needs to be added. The input volume of the activation auxiliary gas is 0.3 to 1920 liters, and the input flow rate of the activation auxiliary gas is 10 to 2000 ml/min.

The above-mentioned activation auxiliary gas system is nitrogen oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or water vapor.

The specific surface area of the above-mentioned porous carbon material is 500 to 3000 m ² /g.

The carbonization temperature of the above-mentioned carbonization treatment is 250 to 800° C., and the carbonization time is 0.5 to 16 hours.

The above technical features have the following advantages:

1. Due to the use of low temperature (less than 550°C) for activation treatment, it is different from the conventional traditional activated carbon process that requires high temperature activation regardless of whether it is a chemical method or a physical method, so it can greatly save energy.

2. Since the raw materials of carbon materials come from waste materials and materials in life, no special preparation is required, and the amount of waste and the impact on environmental damage can be reduced.

3. The prepared porous carbon can increase the specific surface area, has high purity and high thermal stability, and can be used in technical fields such as gas storage, energy storage elements (such as lithium ion batteries and super capacitors).

4. Since the steps of the manufacturing process are quite simple and simple, if it is a pure carbon carbon material, even one activation treatment step can be achieved, and subsequent purification treatment is not required at all.

a: Carbon material before activation

b: Porous carbon material after low temperature activation

[Figure 1] is a manufacturing flow chart of an embodiment of the present invention.

[The second figure] is a surface structure diagram of the porous carbon material of the embodiment of the present invention photographed by a scanning electron microscope (SEM).

[Figure 3] is the hole structure diagram of the porous carbon material of the embodiment of the present invention photographed by a transmission electron microscope (TEM).

[Fig. 4] is the nitrogen adsorption/desorption isotherm diagram of the carbon material before activation and the porous carbon material after low temperature activation according to the embodiment of the present invention.

[Fig. 5] is the distribution diagram of the specific surface area of the porous carbon material of the embodiment of the present invention after activation treatment at different activation temperatures.

Please refer to the first figure, the embodiment of the present invention includes the following steps:

A. A carbon material raw material is subjected to a carbonization treatment. The source of the carbon material raw material can be waste tire carbon, waste plastic, biomass and its waste (such as wood chips, coffee grounds, rice straw, bagasse), pitch, carbon black, graphite, graphene, carbon tubes, etc. one or any combination thereof. If the carbon material is made of waste tire carbon or biomass material waste, it needs to be purified in advance, mainly with 0.5-6M acidic solution or 0.5-6M alkaline solution, and the treatment temperature is 25-6M. 100 ℃, the treatment time is 0.5 to 16 hours, so as to remove impurities. The components of the acidic solution are hydrochloric acid (HCl), sulfuric acid (H ₂ SO ₄ ) or nitric acid (HNO ₃ ), and the components of the alkaline solution are potassium hydroxide (KOH) or sodium hydroxide (NaOH). Then the carbon material is put into a carbonization space for carbonization treatment, the carbonization space is a carbonization furnace, the carbonization temperature of the carbonization treatment is 250 to 800°C, and the carbonization time is 0.5 to 16 hours.

B. Perform an activation treatment on the carbon material raw material, and add an activation gas. The carbon material is placed in an activation space for carbonization treatment. The activation space is an activation furnace, and the activation gas is added into the activation space. The addition amount of the activation gas is 0.3 to 1920 liters. The activated gas system is oxygen and/or air, and the added amount of the oxygen and/or air is 0.3 to 1920 liters, respectively. The activation temperature during the activation treatment is 400 to 550°C, and the optimum activation temperature is 450 to 550°C. The activation time is 30 to 960 minutes, and the optimum activation time is 90 to 300 minutes.

C. During the activation treatment, add an activation auxiliary gas. In another example, when one of the above-mentioned oxygen or air is used for the activation treatment, an activation auxiliary gas must be additionally input, and the activation auxiliary gas system is nitrogen oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or water vapor. The input volume is 0.3 to 1920 liters, and the input flow rate of the activation assist gas is 10 to 2000 ml/min.

In this way, after the carbon material raw material is produced by the above-mentioned manufacturing method, a porous carbon material can be produced. The surface structure of the porous carbon material was photographed by a scanning electron microscope (SEM), as shown in the second figure. In addition, the porous carbon material is photographed by a transmission electron microscope (TEM), as shown in the third figure. And the specific surface area of the porous carbon material is 500 to 3000 m ² /g after being measured by a specific surface area analyzer (BET).

The porous carbon material was further tested by experiments. The nitrogen adsorption/desorption isotherms of the carbon material a before activation and the porous carbon material b after low temperature activation are shown in Figure 4. It can be clearly seen that the porous carbon material has Excellent adsorption/desorption properties. As shown in Figure 5, it is a distribution diagram of the specific surface area of the porous carbon material after the porous carbon material is activated at different activation temperatures. It can be clearly seen from the fifth figure that when the activation temperature is 500°C, the specific surface area of the porous carbon material can reach 2895 m ² /g, which is sufficient to prove that the manufacturing method of the present invention can indeed achieve the effect of increasing the specific surface area. In addition, the prepared porous carbon material has high purity and high thermal stability, and can be applied to technical fields such as gas storage and energy storage components (such as Lithium-ion batteries and Supercapacitors).

Based on the descriptions of the above embodiments, one can fully understand the operation, use and effects of the present invention, but the above-mentioned embodiments are only preferred embodiments of the present invention, which should not limit the implementation of the present invention. Scope, that is, simple equivalent changes and modifications made according to the scope of the patent application of the present invention and the contents of the description of the invention, all fall within the scope of the present invention.

Claims (8)

A method for producing porous carbon, comprising: subjecting a carbon material raw material to a carbonization treatment, placing the carbon material raw material into a carbonization space for carbonization treatment; placing the carbon material raw material after the carbonization treatment in an activated carbon material An activation treatment is carried out in the space, and an activation gas is added. The activation gas system is oxygen and/or air. The addition amount of the oxygen is 0.3 to 1920 liters, and the addition amount of the air is 0.3 to 1920 liters. The activation temperature during the activation treatment is 450 to 550 ° C, the activation time is 30 to 300 minutes, and an activation auxiliary gas is added. The input volume of the activation auxiliary gas is 0.3 to 1920 liters. The input flow rate of the activation auxiliary gas It is 10 to 2000ml/min, so as to make a porous carbon material. The method for producing porous carbon according to claim 1, wherein the source of the carbon material raw material without carbonization treatment is waste tire carbon, waste plastic, biomass, wood chips, coffee grounds, rice straw, bagasse, pitch, carbon One of black, graphite, graphene, carbon tube or any combination thereof. The method for producing porous carbon according to claim 2, wherein the raw carbon material that has not been carbonized is made of waste tire carbon, wood chips, coffee grounds, rice straw or bagasse, and needs to be purified first, and the purification treatment is based on 0.5 to 6M acidic solution or 0.5 to 6M alkaline solution for treatment, the treatment temperature is 25 to 100°C, and the treatment time is 0.5 to 16 hours. The method for producing porous carbon according to claim 3, wherein the components of the acidic solution are hydrochloric acid, sulfuric acid or nitric acid, and the components of the alkaline solution are potassium hydroxide or sodium hydroxide. The method for producing porous carbon according to claim 1, wherein the carbonization space is a carbonization furnace, and the activation space is an activation furnace. The method for producing porous carbon according to claim 1, wherein the activation auxiliary gas system is nitrogen oxide, nitrogen dioxide, carbon monoxide, carbon dioxide or water vapor. The method for producing porous carbon according to claim 1, wherein the specific surface area of the porous carbon material is 500 to 3000 m ² /g. The method for producing porous carbon according to claim 1, wherein the carbonization temperature of the carbonization treatment is 250 to 800° C., and the carbonization time is 0.5 to 16 hours.

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