TW201438991A - Activated carbon microspheres with high specific surface area and method of manufacturing the same - Google Patents

Abstract

The present invention is related to activated carbon microspheres and a method of manufacturing the same. Mesocarbon microspheres are wetly mixed with an alkali activating agent, which can eliminate the loss of the mesocarbon microspheres due to gas blowing during the whole process, as well as elevated yield of the activated carbon microspheres. The resulted activated carbon microspheres possess high specific surface area, total pore volume and specific capacity, as being applied to supercapacitor and other high energy-storage devices.

Description

Method for producing high specific surface area activated carbon microspheres

The present invention relates to an activated carbon and a method for producing the same, and more particularly to an activated carbon microsphere having a high specific surface area for improving productivity and a method for producing the same.

Since supercapacitor refers to the use of activated carbon as an electrode, the surface area of activated carbon increases the surface area, adsorbs more electrons, and increases the storage capacity of the capacitor. Compared to traditional chemical batteries, supercapacitors have many advantages, such as high current density (small size but large capacitance), high operating frequency (up to 1000 Hz), long service life (at least 10 years), and large operating voltage range ( 1~100V can be), ESR series resistance is small, instantaneous discharge is large, production materials are environmentally friendly, charging time is short, etc., so it is widely used in the application range.

One of the key materials for supercapacitors is activated carbon. The carbon material must be activated to obtain activated carbon with a high specific surface area. The activation mode of the carbon material is briefly described below.

US Patent Publication No. US 2007/0128519 A1 discloses a petroleum series asphalt after polycondensation reaction, which is pulverized and then reacted with an alkali gold hydroxide (for example, NaOH) as an activator at a temperature of 100 to 380 ° C. It is activated at 500~700 °C, and 80~85% of the activated carbon powder is prepared by EDLC with 10~15% binder and 1% conductive carbon black. The specific capacitance can reach 30~40F/g. However, this method has the disadvantage of disintegrating into a granular active precursor, which requires a long activation time to achieve deep activation before a high specific surface area product can be obtained. However, after deep activation, the structure of the activated carbon product is easily disintegrated, resulting in insufficient strength, and it is not able to withstand high pressure rolling in the pole piece process, which affects the specific capacity of the prepared electrode sheet.

U.S. Patent No. 7,709,415 discloses a process for producing activated carbon by mixing a chemical activating agent such as potassium hydroxide or sodium hydroxide with a carbon powder, mixing a small amount of a solvent, preparing a solid, and granulating. Although granulation by kneading can effectively attach the activator to the surface of the carbon powder to be activated, it is easy to obtain an activated carbon powder having a high specific surface area; after activation using the anisotropic carbon fiber, a regularly arranged pore can be provided. However, the cost of the anisotropic carbon fiber is too high to be easily mass-produced.

Japanese Patent Publication No. JP-A-2000-313611 discloses the use of a polyhydric alcohol as a binder to produce a granular activated precursor to produce activated carbon. This method utilizes glycerol as a solvent in an amount of from 1 to 30 wt.% based on the total amount of the carbon powder, and an activated carbon powder having a specific surface area of about 1,500 m ² /g can be obtained. Although the polyol has a certain amount of cohesive force at room temperature, the temperature is slightly increased, that is, the viscosity is lowered, and the precursor particle shape cannot be effectively maintained, and it is easy to disintegrate during the activation process.

Chinese Patent Publication No. CN1224033 discloses a method for producing activated carbon using two solvents, one of which is used for dissolution activation. The other, which is used to dissolve the binder, thereby increasing the uniformity of the activator and the binder on the surface of the toner to be activated. In the illustration, one of the two solvents is water for dissolving an activator such as potassium hydroxide, and the other is pyridine to dissolve a binder such as cemented asphalt. By controlling the mixing ratio of water and pyridine, a nearly spherical activated carbon powder product can be obtained. However, the polarity difference between water and pyridine is large, and it is easy to cause precipitation, stratification, etc., so that the activator such as potassium hydroxide is unevenly mixed with the asphalt, resulting in uneven pores generated after activation of the product.

However, the above-mentioned activated carbon, the intermediate product or the final product is insufficient in strength, expensive, and the pores of the activated carbon are not uniform, and it is difficult to apply it to industrial mass production.

In view of the above, there is a need to provide a high specific surface area activated carbon microsphere and a method for its manufacture to overcome various problems faced by conventional processes.

Accordingly, one aspect of the present invention provides a method for producing a high specific surface area activated carbon microsphere which is sufficiently mixed with a carbon activator and an alkaline activator by a wet mixing step before the carbon microsphere is subjected to an activation step. Effectively overcome the conventional dry mixing step to avoid loss of carbon microspheres due to gas blowing during the process, thereby greatly increasing the yield of activated carbon microspheres.

Next, another aspect of the present invention is to provide an activated carbon microsphere having a high specific surface area which is obtained by the above method. The resulting high specific surface area activated carbon microspheres have excellent specific surface area, total pore volume, and yield.

According to the above aspect of the invention, a high specific surface area is proposed Method for producing carbon microspheres. In one embodiment, first, a wet mixing step is performed which mixes the mixed solution for 4 hours at the first temperature. In one example, the mixed solution is composed of carbon microspheres, a basic activator, and a non-organic solvent, wherein the carbon microspheres are mesophase pitch carbon microspheres, and the mesophase pitch carbon microspheres and the alkaline activator are used in combination. The amount, and the amount of the non-organic solvent used, may be, for example, from 3:1 to 5:1, and the first temperature is lower than the boiling point of the non-organic solvent.

Next, a first drying step is performed which removes the non-organic solvent of the above mixed solution at a second temperature to obtain an intermediate product, wherein the second temperature is not lower than the boiling point of the non-organic solvent.

Thereafter, an activation step is performed in which the intermediate product is maintained at a third temperature for 2 hours to 6 hours in the presence of a shielding gas to obtain activated carbon microspheres, wherein the third temperature is at least 800 ° C. The resulting activated carbon microspheres have a yield of at least 70%, and the activated carbon microspheres have a specific surface area of at least 2000 m ² /g and a total pore volume of at least 1.00 cm ³ .

According to an embodiment of the invention, the alkaline activator is an alkali metal hydroxide.

According to an embodiment of the invention, the non-organic solvent is water.

According to an embodiment of the invention, the carbon microspheres described above are not subjected to any carbonization treatment.

According to an embodiment of the present invention, before the wet mixing step, the carbon microspheres may be subjected to a pretreatment step to remove moisture contained in the carbon microspheres.

According to an embodiment of the invention, in the drying step and the activating step Further, the method further comprises, but is not limited to, performing a cooling step on the intermediate product, and then performing a heating step to raise the intermediate product to a third temperature.

According to an embodiment of the present invention, after the activating step, the post-activation treatment step of the obtained activated carbon microspheres may be further included, but not limited to. In one example, the post-activation treatment step may include, but is not limited to, treating the activated carbon microspheres with water vapor, filtering, pickling, hot water washing, and a second drying step.

According to another aspect of the present invention, an activated carbon microsphere is provided which is obtained by the above method.

The high specific surface area activated carbon microsphere of the present invention and the preparation method thereof are characterized in that the carbon microspheres and the alkaline activator are sufficiently mixed by the wet mixing step before the carbon microspheres are subjected to the activation step, thereby effectively overcoming the conventional dry mixing. The step loses carbon microspheres due to gas blowing, thereby greatly increasing the yield of activated carbon microspheres.

100‧‧‧ method

101‧‧‧Wet mixing step

103‧‧‧First drying step

105‧‧‧Activation step

107‧‧‧Steps to obtain activated carbon microspheres

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; A partial manufacturing flow chart of the microspheres.

As described above, the present invention provides a method for producing activated carbon microspheres having a high specific surface area, which is used before the carbon microspheres are subjected to an activation step. The mixing step sufficiently mixes the carbon microspheres with the alkaline activator to effectively overcome the conventional dry mixing step to avoid loss of carbon microspheres due to gas blowing during the process, thereby greatly increasing the yield of the activated carbon microspheres.

Referring to FIG. 1 , a partial manufacturing flow diagram of a high specific surface area activated carbon microsphere according to an embodiment of the present invention is shown. In one embodiment of the method 100 of the present invention, first, as shown in step 101, a wet mixing step 101 is performed, which is performed at a first temperature and the mixed solution is mixed for 4 hours. The aforementioned mixed solution is composed of carbon microspheres, an alkali activator, and a non-organic solvent. In one example, the above-described suitable carbon microspheres can be, for example, commercially available mesophase pitch carbon microspheres, wherein the mesophase pitch carbon microspheres have at least 60% (v/v) without any carbonization treatment. The intermediate phase layer structure and the quinoline insoluble (hereinafter referred to as QI) are preferably more than 95% (w/w) or more.

In the above examples, the above alkaline activator is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, and potassium hydroxide is preferred.

In the mixed solution, the weight ratio of the mesophase pitch carbon microspheres to the alkaline activator may be, for example, 1:3. Secondly, the total amount of mesophase pitch carbon microspheres and alkaline activator used in the mixed solution, and the amount of non-organic solvent used, the weight ratio of the two may be, for example, 3:1 to 5:1, but 4:1. It is better.

In general, the first temperature used in the above wet mixing step 101 is generally lower than the boiling point of the non-organic solvent, thereby allowing the carbon microspheres and the alkaline activator to be sufficiently mixed uniformly to complete the alkaline activator. Covered on the surface of carbon microspheres.

One of the features of the present invention is that the above non-organic solvent is a single solvent. System, and exclude the addition of other solvents. In one embodiment, the non-organic solvent may be, for example, water, so the first temperature may be, for example, 50 ° C to 100 ° C, preferably 60 ° C to 80 ° C, more preferably 80 ° C.

In addition, before the wet mixing step 101, a pre-treatment step may be selectively performed, wherein the carbon microspheres are placed at a temperature of 260 ° C to 650 ° C to substantially remove the impurities contained in the carbon microspheres. The volatile component avoids the escape of the reaction gas in the subsequent activation process, and instead takes out the carbon microspheres and affects the yield.

After the above wet mixing step, as shown in step 103, a first drying step 103 is performed which is carried out at a second temperature to remove the non-organic solvent of the mixed solution to obtain an intermediate product. In one embodiment, the second temperature may be, for example, not lower than the boiling point of the non-organic solvent, wherein the second temperature may be, for example, 100 ° C to 130 ° C, preferably 110 ° C to 120 ° C, and 110 °C is better. Secondly, since the first drying step 103 is for removing the non-organic solvent of the mixed solution, various conventional drying methods can be used or combined. Further, the time of the first drying step 103 may be, for example, 8 hours to 24 hours, but the present invention is not limited to the ones herein, depending on the drying method used.

Thereafter, as shown in step 105, an activation step 105 is performed in which the intermediate product is maintained at a third temperature for 2 hours to 6 hours in the presence of a shielding gas to obtain activated carbon microspheres, such as a step. 107 is shown. The third temperature is preferably at least 800 ° C, and more preferably 800 ° C to 900 ° C.

It should be noted here that in the above drying step 103 and the activation step Between 105, optionally, the step of cooling and the step of heating are included. In this embodiment, the cooling step described above can be cooled to room temperature (about 0 ° C to about 50 ° C) using conventional cooling means. In the above heating step, the temperature rise rate of 1 ° C to 3 ° C per minute can be used to raise the intermediate product to the aforementioned third temperature.

According to an embodiment of the present invention, after the activating step 105, the activated carbon microspheres are further selectively subjected to a post-activation treatment step. In one example, a suitable post-activation treatment step can include, but is not limited to, treating the activated carbon microspheres with water vapor, then filtering, pickling, hot water cleaning, and a second drying step. The aforementioned steam treatment, filtration, pickling, hot water washing, and second drying steps can be carried out in a conventional manner. In other examples, the activated carbon microspheres may be treated with steam for, for example, 5 hours to 10 hours, while the second drying step may dry the activated carbon microspheres, for example, at 120 ° C for, for example, 5 hours to 10 hours.

In another example, the wet mixing step, the drying step, the cooling step, the heating step, and the activating step described above may be performed in the presence of a shielding gas, wherein suitable shielding gases may include, but are not limited to, for example, nitrogen, argon, helium. Gas or any combination of the above.

It is worth mentioning that, since the present invention utilizes the wet mixing step to thoroughly mix the carbon microspheres with the alkaline activator and selectively carry out the pretreatment step to remove the volatile components contained in the carbon microspheres, it is effective to overcome the conventional dry type. The mixing step loses carbon microspheres due to gas blowing, thus greatly increasing the yield of activated carbon microspheres by at least 70%. In this way, the obtained activated carbon microspheres have a high specific surface area, a high total pore volume, and a high specific capacitance value, and have a specific surface area of at least 2000 m ² /g, a total pore volume of at least 1.00 cm ³ , and a specific capacitance. The value is at least 110 F/g. In other examples, the resulting activated carbon microspheres have a yield of at least 75%, a specific surface area of at least 2500 m ² /g, a total pore volume of at least 1.00 cm ³ , and a specific capacitance value of at least 160 F/g. Thus, the resulting activated carbon microspheres can be used in ultracapacitors and other high power energy storage devices.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention. Those skilled in the art can make various changes without departing from the spirit and scope of the present invention. Retouching.

Example 1

First, 1000 g of mesophase pitch carbon microsphere G (green mesophase powder, GMP; GP-24; fix carbon>90%; volatile matter 8 ± 2%; QI is ≧ 95%, average particle size (D ₅₀ ) 25μm; Sinosteel Carbon Chemical Co., Ltd., Republic of China; A) placed at a temperature of 260 ° C to 650 ° C to remove the volatile components contained therein.

Next, 1000 g of mesophase pitch carbon microspheres G (QI is ≧95%, average particle diameter (D ₅₀ ) is 25 μm; China Steel Carbon Chemical Co., Ltd.; A), 3000 g of potassium hydroxide (KOH) Purity 95%; Taiwan Paper Co., Ltd., Republic of China; B) and 1000 mL of pure water (C) mixed solution, added to the rotary furnace (made in China Steel), mixed the above mixed solution at 70 ° C for 4 hours So that potassium hydroxide is completely coated on the surface of the carbon microspheres. Dry at 110 ° C for 4 hours to obtain an intermediate product. After the intermediate product is cooled to room temperature (0 ° C to 50 ° C), an activation step is carried out by linear heating to raise the temperature of the intermediate product to 900 ° C and maintain the temperature at a temperature increase rate of 2 ° C per minute. Up to 6 hours to obtain activated carbon microspheres.

In the above drying and activating steps, the furnace wall may be periodically struck to cause the intermediate product attached to the furnace wall to fall, and the intermediate product is uniformly tumbling and heated in the rotary furnace. The aforementioned wet mixing step, drying step, cooling step, heating step, and activation step are carried out in the presence of a shielding gas at a flow rate of, for example, 1.0 L to 2.0 L of nitrogen per minute.

Next, a post-activation treatment step of passing water vapor into a rotary furnace, treating the activated carbon microspheres, and performing filtration, pickling, hot water washing, and the like is performed. Then, the activated carbon microspheres were dried in an oven at 120 ° C for 24 hours to remove the moisture of the activated carbon microspheres.

The obtained activated carbon microspheres were weighed to calculate the yield, and the specific surface area (BET; m ² /g), average pore diameter (nm), total pore volume were measured using a commercially available pore size analyzer (Micromeritics, model ASAP2020). (cm ³ ), and its specific capacitance value (F/g) was measured by the above aperture analyzer.

Example 2

The preparation method of Example 1 was different in that Example 2 was a condition for changing the activation reaction, and the formulation and test results were also shown in Table 1.

Comparative Example 1 to Comparative Example 2

The preparation method of Example 1 was different in that Comparative Example 1 to Comparative Example 2 were changed to a dry mixing step, and the process conditions of the activation reaction were changed, and the formulation and test results were also shown in Table 1.

As can be seen from the results of Table 1, the activated carbon microspheres of Examples 1 to 2 have a specific surface area of at least 2000 m ² /g, a total pore volume of at least 1.00 cm ³ , a high specific capacitance of at least 110 F/g, and at least 70% yield, the object of the present invention is achieved, wherein the activated carbon microsphere of Example 1 further has a specific surface area of at least 2500 m ² /g, a total pore volume of at least 1.00 cm ³ , at least 160 F/g. High specific capacitance and a yield of at least 75%. However, the yields of the carbon microspheres of Comparative Example 1 and Comparative Example 2 were all less than 40%.

It should be noted that the present invention describes a high specific surface area activated carbon microsphere of the present invention and a method for producing the same according to a specific material, a process, a reaction condition, an analytical method or a specific instrument, but in the technical field to which the present invention pertains It is to be understood by those skilled in the art that the present invention is not limited thereto, and the high specific surface area activated carbon microspheres of the present invention and the method for producing the same may also use other materials, processes, and reaction conditions without departing from the spirit and scope of the present invention. , analytical methods or instruments.

It can be seen from the above embodiments of the present invention that the high specific surface area activated carbon microspheres of the present invention and the method for producing the same have the advantages that the carbon microspheres and the alkaline activator are sufficiently mixed by the wet mixing step, which can effectively overcome the process in the process. The gas blows and loses carbon microspheres, thereby greatly increasing the yield of activated carbon microspheres, which in turn is used in ultracapacitors and other high-power energy storage devices.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

100‧‧‧ method

101‧‧‧Wet mixing step

103‧‧‧First drying step

105‧‧‧Activation step

107‧‧‧Steps to obtain activated carbon microspheres

Claims (17)

A method for producing high specific surface area activated carbon microspheres, comprising: performing a wet mixing step of mixing a mixed solution for 4 hours at a first temperature, wherein the mixed solution is composed of a carbon microsphere, An alkali activator and a non-organic solvent, wherein the carbon microspheres are mesophase pitch carbon microspheres, and the carbon microspheres and one of the alkaline activators are used in combination with one weight of the non-organic solvent. The ratio is from 3:1 to 5:1, and the first temperature is not higher than one of the boiling points of the non-organic solvent; performing a drying step of removing the non-organic solvent of the mixed solution at a second temperature to Obtaining an intermediate product, wherein the second temperature is not lower than the boiling point of the non-organic solvent; and performing an activation step in the presence of the shielding gas to maintain the intermediate product at a third temperature up to 2 Hours to 6 hours to obtain an activated carbon microsphere, wherein the third temperature is at least 800 ° C, and wherein one of the activated carbon microspheres has a yield of at least 70%, and the activated carbon microsphere has at least one of 2000 m ² / g specific surface And at least one of 1.00cm ³ total pore volume. The method for producing a high specific surface area activated carbon microsphere according to the first aspect of the invention, wherein the alkaline activator is an alkali metal hydroxide. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the alkaline activator is sodium hydroxide or potassium hydroxide. A method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the weight ratio is 4:1. A method for producing a high specific surface area activated carbon microsphere according to claim 4, wherein a weight ratio of the mesophase pitch carbon microsphere to the alkaline activator is 1:3. The method for producing a high specific surface area activated carbon microsphere according to the first aspect of the invention, wherein the non-organic solvent is water. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the carbon microsphere is not subjected to any carbonization treatment. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the first temperature is from 50 ° C to 100 ° C. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the first temperature is from 60 ° C to 80 ° C. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein before the wet mixing step, at least comprising: performing a pretreatment step of placing the carbon microspheres at 260 °C to 650 At a temperature of °C, the moisture contained in the carbon microspheres is removed. The method for producing a high specific surface area activated carbon microsphere according to claim 1, wherein the second temperature is from 100 ° C to 130 ° C. The method for producing a high specific surface area activated carbon microsphere according to the first aspect of the invention, wherein the third temperature is from 800 ° C to 900 ° C. According to the method for producing high specific surface area activated carbon microspheres according to claim 1, in the drying step and the activating step, at least: performing a cooling step to cool the intermediate product to 0 ° C Up to 50 ° C; and a heating step of raising the intermediate product to the third temperature using a temperature increase rate of 1 ° C to 3 ° C per minute. The method for producing a high specific surface area activated carbon microsphere according to claim 13, wherein the wet mixing step, the drying step, the cooling step, the heating step, and the activating step are performed on a protective gas The presence is carried out and the shielding gas is nitrogen, argon, helium or any combination of the above. The method for producing a high specific surface area activated carbon microsphere according to claim 1 of the patent application, after the activation step, further comprises at least a pair The activated carbon microspheres are subjected to a post-activation treatment step. The method for producing a high specific surface area activated carbon microsphere according to claim 15, wherein the post-activation treatment step comprises: treating the activated carbon microsphere with steam; and performing the activated carbon microsphere a filtering step; performing a pickling step on the activated carbon microspheres; performing a hot water washing step on the activated carbon microspheres; and performing a second drying step to remove moisture contained in the activated carbon microspheres. An activated carbon microsphere obtained by the method according to any one of claims 1 to 16.