TWI549908B - Method of producing active carbon and application thereof - Google Patents

Description

Method for producing activated carbon and its application

This invention relates to an activated carbon material, and more particularly to an activated carbon material having a high specific surface area.

The demand for environmental protection has made the electric vehicle industry flourish. When an electric vehicle is running, a supercapacitor in an electric vehicle can store or release electrical energy to provide vehicle kinetic energy. The charging and discharging of supercapacitors must be achieved by using activated carbon with a high specific surface area, so that a key technology for producing supercapacitors of activated carbon having a high specific surface area is obtained.

Conventionally, a method of producing activated carbon having a high specific surface area generally produces activated carbon by a chemical activation method. However, the surface of the activated carbon produced by the above method may leave excessive metal. When the supercapacitor is charged and discharged, the residual metal on the surface of the activated carbon corrodes the electrode substrate of the supercapacitor, and the electrode substrate is separated from the activated carbon layer, thereby reducing the service life of the supercapacitor.

In order to solve the aforementioned defects of metal residues, Nippon Oil has proposed a method of reducing the residual amount of metal by using a large amount of water and a heat treatment step (about 450 ° C to 800 ° C). But this method takes a lot of money The water (about 100 times the weight of the activated carbon), and the heat treatment step relatively increases the energy cost, and greatly increases the production cost of the activated carbon.

Kuraray Chemical has proposed another method that utilizes potassium hydroxide as an activator and uses carbonic acid as the first neutralizing reactant and hydrochloric acid as the second neutralizing reactant to reduce the residual metal of activated carbon. However, hydrochloric acid as a neutralizing reactant easily leaves chlorine ions on the surface of the activated carbon. Moreover, when the supercapacitor is charged and discharged, residual chlorine ions form a gas, thereby reducing the performance of the supercapacitor.

In view of the above, it is not necessary to provide a method for producing activated carbon and an application thereof to improve the defects of the conventional activated carbon manufacturing method and its application.

Accordingly, an aspect of the present invention provides a method for producing activated carbon which has a good specific surface area and a low residual amount of metal.

Another aspect of the present invention is to provide an activated carbon which is produced by the above-described manufacturing method.

Yet another aspect of the present invention is to provide a supercapacitor comprising the aforementioned activated carbon.

According to one aspect of the present invention, a method of producing activated carbon is proposed. The manufacturing method first performs a chemical activation process to form an activated product, wherein the chemical activation process heats the asphalt powder and the alkaline activator under an inert gas to an activation temperature to form an activated product, and the asphalt powder and the alkaline activator The weight ratio is 1:3.

Then, the aforementioned activation product is subjected to a deactivation process. This deactivation process passes the water vapor to the activated product to form a slurry.

After the deactivation process, the first neutralization process is performed. The first neutralization process washes the slurry with water and neutralizes the slurry with an acidic aqueous solution such that the pH of the slurry does not exceed 7, thereby forming a deactivated product.

Next, the deactivated product is subjected to a drying process under an inert gas to form an intermediate product in which the water content of the intermediate product is from 0.01% by weight to 5% by weight based on 100% by weight based on the weight of the deactivated product.

After the drying process, a second neutralization process is performed. The second neutralization process immerses the intermediate product in an aqueous oxidizing acid solution to form activated carbon, wherein the concentration of the aqueous oxidizing acid solution is from 0.5 weight percent to 10 weight percent.

According to an embodiment of the present invention, after the second neutralization process, the manufacturing method further comprises a carbonization process for the activated carbon, wherein the carbonization process has a temperature of at least 800 °C.

According to another embodiment of the present invention, the aforementioned activation temperature is 650 ° C to 900 ° C, and the rate of temperature increase of the chemical activation process is 100 ° C / hour.

According to still another embodiment of the present invention, the aforementioned alkaline activator comprises potassium hydroxide or sodium hydroxide.

According to still another embodiment of the present invention, the aqueous oxidizing acid solution may be an aqueous solution of nitric acid or an aqueous solution of sulfuric acid.

According to still another embodiment of the present invention, the temperature of the drying process may be from 110 ° C to 150 ° C.

According to still another embodiment of the present invention, the activated carbon comprises a specific surface area of at least 2000 square meters per gram, a potassium content of not more than 150 ppm, an iron content of not more than 30 ppm, a nickel content of not more than 110 ppm, and Not more than 10 ppm of chromium.

According to another aspect of the invention, an activated carbon is proposed. The activated carbon comprises a specific surface area of at least 2000 square meters per gram, a potassium content of not more than 150 ppm, an iron content of not more than 30 ppm, a nickel content of not more than 110 ppm, and a chromium content of not more than 10 ppm.

According to still another aspect of the present invention, a supercapacitor is proposed. This supercapacitor contains the aforementioned activated carbon.

The method for producing activated carbon of the present invention and the application thereof are characterized in that a drying process is used to dry and deactivate the product to remove moisture remaining in the slit of the activated carbon, thereby reducing the residual metal amount of the activated carbon, thereby increasing the activated carbon. Quality.

100a‧‧‧ method

100b‧‧‧ method

110‧‧‧Revitalization process

120‧‧‧Deactivation process

130‧‧‧First neutral

140‧‧‧Drying process

150‧‧‧Second neutralization process

151‧‧‧Carbonization process

150‧‧‧Formation of activated carbon

Fig. 1a is a view showing a method of producing activated carbon according to an embodiment of the present invention.

Fig. 1b is a view showing a method of producing activated carbon according to another embodiment of the present invention.

The making and using of the embodiments of the invention are discussed in detail below. However, it will be appreciated that the embodiments provide many applicable inventive concepts that can be implemented in a wide variety of specific content. The specific embodiments discussed are illustrative only and are not intended to limit the scope of the invention.

Please refer to FIG. 1a, which illustrates a method for producing activated carbon according to an embodiment of the present invention. In one embodiment, method 100a is followed by a chemical activation process, as shown in step 110. The chemical activation process heats the asphalt powder and the alkaline activator to an activation temperature under an inert gas to form an activation product, and the activation temperature may be 650 ° C to 900 ° C, wherein the chemical activation process has a heating rate of 100 ° C / hour.

The weight ratio of the foregoing asphalt powder to the alkaline activator may be 1:3. In one embodiment, depending on the characteristics of the activated carbon to be produced, the user can adjust the weight ratio of the asphalt powder to the alkaline activator to produce an activated carbon that satisfies the demand.

The alkaline activator can include, but is not limited to, potassium hydroxide, sodium hydroxide, other suitable alkaline activators, or any mixture of the foregoing. The alkaline activator may preferably be potassium hydroxide or sodium hydroxide, and more preferably potassium hydroxide.

In an embodiment, the alkaline activator preferably comprises a water soluble metal ion. The water-soluble metal ion is preferably a potassium ion or a sodium ion.

The activating product described above is then subjected to a deactivation process, as shown in step 120.

The deactivation process is mainly used to remove the activity of the aforementioned residual alkali activator for subsequent processes.

The deactivation process described above applies water vapor to the activated product to form a slurry, and the deactivation process passes an excess of saturated water vapor to remove the activity of the remaining alkaline activator.

In one embodiment, the aforementioned deactivation process can be carried out using techniques and methods well known to those of ordinary skill in the art to remove residual alkaline activator activity.

After the deactivation process, a first neutralization process is performed, as shown in step 130. The first neutralization process washes the slurry with water and neutralizes the slurry with an acidic aqueous solution so that the pH of the slurry does not exceed 7, and a deactivated product can be formed.

When the first neutralization process described above is carried out, the pH of the solvent slowly decreases as the acidic aqueous solution is added dropwise. In one embodiment, when the pH of the solution is less than 7 and maintained for 5 minutes, this condition represents that the first neutralization process has been completed.

Next, a drying process is performed, as shown in step 140. This drying process is carried out on an deactivated product under an inert gas to form an intermediate product. The water content of the intermediate product is from 0.01% by weight to 5% by weight based on 100% by weight of the deactivated product.

The drying process can have a temperature of from 110 ° C to 150 ° C.

After the drying process, a second neutralization process is performed to form activated carbon, as shown in steps 150 and 160.

The second neutralization process described above immerses the intermediate product in an aqueous oxidizing acid solution, wherein the concentration of the aqueous oxidizing acid solution is from 0.5% by weight to 10% by weight, and the concentration of the aqueous oxidizing acid solution is preferably 1% by weight. The aqueous oxidizing acid solution may comprise a water solution of nitric acid, an aqueous solution of sulfuric acid, another suitable aqueous solution of oxidizing acid or any mixture of the above materials.

In one embodiment, the aqueous oxidizing acid solution is preferably an aqueous solution of nitric acid or an aqueous solution of sulfuric acid, and more preferably an aqueous solution of nitric acid.

If the concentration of the aqueous solution of the oxidizing acid is more than 10% by weight, the time of the second neutralization process is shortened to prevent the aqueous acid acid solution of the peracid from eroding the activated carbon wall between the slits of the activated carbon, and reducing the specific surface area of the activated carbon. .

If the concentration of the aqueous solution of the oxidizing acid is less than 0.5% by weight, the time of the second neutralization process needs to be prolonged, and the amount of the aqueous solution of the oxidizing acid needs to be increased to ensure that the aqueous solution of the oxidizing acid can surely remove the residual metal, thereby increasing the production of activated carbon. cost.

When the aforementioned drying process is carried out, the high temperature environment can remove the surface of the activated carbon and the residual water in the slit, so that when the second neutralization process is carried out, the aqueous oxidizing acid solution can overcome the influence of the surface tension and deepen by capillary action. In the slit, the metal remaining in the slit can be oxidized to form metal ions and dissolved in the aqueous solution of oxidizing acid, thereby effectively removing the metal remaining in the activated carbon and improving the quality of the activated carbon.

Secondly, when the aqueous solution of oxidizing acid can penetrate into the slit of the activated carbon, the metal ion can be dissolved in the aqueous solution of oxidizing acid, and the metal ion can be removed by diffusion, thereby reducing the amount of residual metal of the activated carbon.

Therefore, when the moisture content of the aforementioned intermediate product is more than 5% by weight, the above-mentioned slit still retains excess water, so that the subsequent second neutralization The aqueous oxidizing acid solution used in the process does not penetrate into the slits, and thus the residual metal on the surface of the slit is not effectively oxidized.

If the moisture content of the intermediate product is less than 0.01% by weight, although the moisture in the fine slit is thoroughly dried to facilitate the penetration of the aqueous solution of the oxidizing acid into the slit, the drying process takes too long and the benefit is not obvious, thereby causing Waste of energy.

Please refer to FIG. 1b, which illustrates a method for producing activated carbon according to another embodiment of the present invention. The step flow of the method 100b is substantially the same as the step flow of the method 100a. The difference between the two is that after the step 150, the method 100b further includes performing a carbonization process, as shown in step 151. The carbonization process has a temperature of at least 800 °C.

The carbonization process described above can further remove residual impurities in the activated carbon, and the high temperature carbonization process can crack the functional groups on the surface of the activated carbon to further extract the quality of the activated carbon.

In one embodiment, the activated carbon produced by the present invention has a specific surface area of at least 2000 square meters per gram, a potassium content of not more than 150 ppm, an iron content of not more than 30 ppm, a nickel content of not more than 110 ppm, and Not more than 10 ppm of chromium.

Since the produced activated carbon has a good specific surface area and the amount of residual metal is extremely small, the activated carbon produced can be applied to supercapacitors, and other applications that can satisfy the required characteristics, for example, in the field of medicine. Wait.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention, and various modifications and refinements can be made without departing from the spirit and scope of the invention.

Preparation of activated carbon

First, the asphalt powder and potassium hydroxide were mixed at a weight ratio of 1:3, and the temperature was raised to 900 ° C at a heating rate of 100 ° C / hour in a nitrogen atmosphere to carry out an activation process.

After the reaction was completed, the temperature was lowered to room temperature, and the deactivation step was carried out with an excess of saturated water vapor to remove the residual potassium hydroxide activity to form a slurry.

Next, the activated carbon is washed with water and the activated carbon is neutralized with sulfuric acid until the pH of the solution is less than 7, and is maintained for at least 5 minutes to form a deactivated product. Among them, the volume ratio of water to activated carbon is 5:1.

Then, the activated carbons of Examples 1 and 2 and Comparative Examples 1 and 2 were prepared according to the first table.

Example 1

The above deactivated product was subjected to a drying process at a temperature of 120 ° C to form an intermediate product in which the water content of the intermediate product was 0.01% by weight. Next, the intermediate product was neutralized with a 1% by weight aqueous solution of nitric acid, wherein the weight ratio of the aqueous solution of nitric acid to the activated carbon was 10:1.

After 4 hours, the activated carbon was filtered and the activated carbon was dried at a temperature of 120 °C. After 24 hours, the activated carbon of Example 1 was obtained.

The aforementioned moisture content is calculated according to the following formula:

Wherein W _i represents the weight of the deactivated product of water, and W _f represents the weight of the intermediate product.

The obtained activated carbon is evaluated in the following evaluation manner, and the obtained results are shown in Table 1, wherein the pore diameter analysis and the ash content of the activated carbon are respectively known as pore size analysis well known to those skilled in the art to which the present invention pertains. It is measured by the instrument and the ash measurement method, and the metal content is also measured by the well-known Inductively Coupled Plasma (ICP) analysis method, so it will not be further described herein.

Example 2

The second embodiment is the same as the preparation method of the activated carbon of the first embodiment, except that the embodiment 2 is used to change the process parameters of the drying process, and the process parameters and evaluation results are shown in the first table. I will not repeat them here.

Comparative Example 1 and Comparative Example 2

Comparative Example 1 and Comparative Example 2 were prepared in the same manner as in the production method of the activated carbon of Example 1, except that Comparative Example 1 and Comparative Example 2 were not subjected to a drying process, and Comparative Example 2 was not neutralized with nitric acid. mid product. The evaluation results of Comparative Example 1 and Comparative Example 2 are shown in Table 1, and are not described here.

From the results of the first table, it can be seen that compared with the comparative example 1, the neutralization process of the first embodiment and the second embodiment can effectively reduce the potassium content, the iron content, and the nickel content. The amount and the chromium content, and both of Example 1 and Example 2 still have a specific surface area of at least 2000 square meters per gram.

It can be seen from the above embodiments of the present invention that the method for producing activated carbon of the present invention has the advantages of drying the water remaining in the fine slit of the activated carbon by a drying process, so that the aqueous oxidizing acid solution used later can be infiltrated by capillary action. Slit to oxidize metal and form water-soluble metal ions, which can reduce the residual metal content by diffusion, thereby improving the quality of activated carbon.

Secondly, the activated carbon obtained by the method for producing activated carbon of the present invention has a good specific surface area, and can be applied to a supercapacitor and improve the performance of the capacitor.

It can be seen from the above embodiments of the present invention that the method for producing activated carbon of the present invention has the advantages of drying the moisture remaining in the slit of the activated carbon by the drying process, so that the aqueous solution of oxidizing acid used in the second neutralization process can be It penetrates into the slits and effectively removes residual metals, thereby improving the quality of activated carbon.

The present invention has been disclosed in the above embodiments, and is not intended to limit the present invention. Any one of ordinary skill in the art to which the present invention pertains can make various changes without departing from the spirit and scope of the invention. The scope of protection of the present invention is therefore defined by the scope of the appended claims.

100a‧‧‧ method

110‧‧‧Chemical activation process

120‧‧‧Deactivation process

130‧‧‧First Intermediate Process

140‧‧‧Drying process

150‧‧‧Second neutralization process

160‧‧‧Formation of activated carbon

Claims (7)

A method for producing activated carbon, comprising: performing a chemical activation process, wherein the chemical activation process heats an asphalt powder and an alkali activator to an activation temperature under an inert gas to form an activation product, and a weight ratio of the asphalt powder to the alkaline activator is 1:3; performing a deactivation process, wherein the deactivation process is to pass a water vapor to the activated product to form a slurry; and perform a first a neutralization process, wherein the first neutralization process washes the slurry with water and neutralizes the slurry with an acidic aqueous solution such that a pH of the slurry does not exceed 7 to form a deactivated product; The deactivated product is subjected to a drying process under the inert gas to form an intermediate product, wherein one of the intermediate products has a water content of 0.01% by weight to 5% by weight based on 100% by weight of the deactivated product; And performing a second neutralization process, wherein the second neutralization process immerses the intermediate product in an aqueous oxidizing acid solution to form the activated carbon, wherein a concentration of the aqueous oxidizing acid solution is 0.5% by weight to 10% by weight. The method for producing activated carbon according to claim 1, wherein after the second neutralization process, the method further comprises: performing a carbonization process on the activated carbon, wherein a temperature of the carbonization process is at least 800 °C. The method for producing activated carbon according to claim 1, wherein the activation temperature is 650 ° C to 900 ° C, and one of the chemical activation processes has a heating rate of 100 ° C / hour. The method for producing activated carbon according to claim 1, wherein the alkaline activator comprises potassium hydroxide or sodium hydroxide. The method for producing activated carbon according to claim 1, wherein the aqueous oxidizing acid solution is an aqueous solution of nitric acid or an aqueous solution of sulfuric acid. The method for producing activated carbon according to Item 1, wherein the temperature of the drying process is from 110 ° C to 150 ° C. The method for producing activated carbon according to claim 1, wherein the activated carbon comprises a specific surface area of at least 2000 square meters per gram, a potassium content of not more than 150 ppm, and an iron content of not more than 30 ppm, which is not high. The nickel content is 110 ppm, and the chromium content is not higher than 10 ppm.