KR20200042689A - Manufacturing Method of Activated Carbon using Kenaf - Google Patents

Abstract

The present invention provides a method for manufacturing a porous carbon material using kenaf, a method for manufacturing a porous activated carbon material, and a method for manufacturing an electrode material. More specifically, the present invention has an effect of providing: a method for manufacturing a porous carbon material which effectively utilizes plant waste and can be used as electrochemical cell having a capacity equal to or higher than the capacity of an existing porous carbon material or an adsorbent; a method for manufacturing a porous activated carbon material; and a method for manufacturing an electrode material.

Description

{Manufacturing Method of Activated Carbon using Kenaf}

The present invention relates to a method of manufacturing a porous carbon material using Kenaf, a method of manufacturing a porous activated carbon material, and a method of manufacturing an electrode material.

Recently, the use of biomass is required to reduce greenhouse gas emissions. As a result, it is technically possible to replace wood-based products, such as paper and bio-ethanol, with kenaf having equivalent performance to wood. As a method of utilizing plant wastes such as kenaf and rice husk, a method of producing carbon powder by heating and carbonizing them has been studied. For example, Japanese Unexamined Patent Publication No. 2014-94883 discloses the production of porous carbon carbonized at 800 ° C to 1400 ° C using rice, rice, barley, wheat, rye, blood, crude rice, rice husk, reed, and stem seaweed as materials. Methods are described.

Cell walls of many plants are composed mainly of cellulose, hemicellulose, and lignin. For this reason, when the plant is heated, part of the decomposition product becomes gas and is released into the atmosphere, and partly remains as a carbide.

Hemicellulose can be used as a raw material for high value added sugar components. For this reason, when heating only plants, even high value added components are decomposed, and there is a problem that the plant components cannot be used efficiently. The present invention has been devised in view of the above circumstances, and can effectively be used as an electrode material of an electrochemical cell such as an electric double layer capacitor or a battery, which effectively utilizes plant waste and has a capacity equal to or higher than that of a conventional porous carbon material, and can also be used as an adsorbent. An object is to provide a method for producing a porous carbon material, a method for producing a porous activated carbon material, and a method for producing an electrode material.

Japanese Patent Application Publication No. 2014-94883

The present invention is to solve the above problems, and an object of the present invention is to provide a method for manufacturing a porous carbon material using Kenaf, a method for manufacturing a porous activated carbon material, and a method for manufacturing an electrode material.

The present invention for achieving the above object is a sugar extraction process for extracting hemicellulose-derived sugar from Kenaf, a recovery process for recovering solid residues generated by extracting the sugar, and a heating carbonization process for heating and solidifying the solid residue. And a method of manufacturing a porous carbon material.

In addition, the sugar extraction process may be a pressurized hot water treatment process.

In addition, the pressurized hot water treatment process may be performed at 160 ° C or higher and 220 ° C or lower.

Further, the heat carbonization treatment process may be performed at 500 ° C or higher.

In addition, the plant biomass may be kenaf.

In addition, ultrasonic heating using a metal derivative may be performed in parallel during the heating and carbonization process.

In addition, the plant biomass may be irradiated with radiation during the recovery process or prior to the heat carbonization treatment process.

In addition, a sugar extraction process for extracting hemicellulose-derived sugar from a plant biomass, a recovery process for recovering solid residues generated by extracting the sugar, and a heat carbonization treatment process for heating and carbonizing the solid residue, and obtained by the heat carbonization treatment It may be a method for producing a porous activated carbon material, comprising a regeneration process for regenerating the porous carbon material.

As described above, the method for producing a porous carbon material that can effectively utilize the plant waste according to the present invention and can be used as an electrode material and an adsorbent for an electrochemical cell having a capacity equal to or higher than that of a conventional porous carbon material, porous There is an effect of providing a method of manufacturing an activated carbon material and a method of manufacturing an electrode material.

It will be described in detail an embodiment that can be easily carried out by those of ordinary skill in the art to which the present invention pertains. However, in the detailed description of the operating principle for the preferred embodiment of the present invention, if it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

Throughout the specification, when a part is connected to another part, this includes not only the case of being directly connected, but also the case of being connected indirectly with another element in between. In addition, the inclusion of any component does not exclude other components unless specifically stated otherwise, means that other components may be further included.

The method for producing a porous carbon material of the present invention includes a sugar extraction process for extracting hemicellulose-derived sugar from a plant biomass, a recovery process for recovering solid residues generated by extracting the sugar, and a heating carbonization process for heating and solidifying the solid residue. Be equipped.

In the method for producing a porous carbon material of the present embodiment, sugars derived from hemicellulose are first extracted from a plant biomass as a raw material. Hemicellulose is a generic term for polysaccharides excluding cellulose, which is contained in plant cell walls. Depending on the plant, the content of hemicellulose is about 10 to 30%. Xylan, the main component of hemicellulose, is a material of xylo-oligosaccharide, a sugar material with high added value.

The sugar-added material with high added value is extracted by a sugar extraction process, and the extracted sugar can be used as a food, pet or livestock feed. In addition, it is considered that by extracting the sugar in advance before the heat carbonization treatment, a porous carbon material in which the missing traces of the sugar develops a porous structure and has finer pores can be produced. The sugar component having a high added value can be effectively utilized by subjecting the plant to hot water treatment and extracting sugar in advance. In addition, since the water-soluble inorganic component is eluted, a homogeneous porous carbon material having few impurities and suppressing variation due to lots can be produced. In addition, it is thought that the ingredient to be ash is extracted together with sugar.

In the sugar extraction process, first, the plant biomass of the raw material is ground into three pieces. The plant biomass that can be used as a raw material is not particularly limited, for example, broad-leaved trees such as bamboo and buckthorn, and conifers such as cedar, rice straw, straw, rice husk, and Kenaf. In this embodiment, it is preferable to use bamboo as a plant biomass from the viewpoint of countermeasures against bamboo damage.

Cell walls of many plants are composed mainly of cellulose, hemicellulose, and lignin. For this reason, when the plant is heated, part of the decomposition product becomes gas and is released into the atmosphere, and partly remains as a carbide.

Hemicellulose can be used as a raw material for high value added sugar components. For this reason, when heating only plants, even high value added components are decomposed, and there is a problem that the plant components cannot be used efficiently. The present invention has been devised in view of the above circumstances, and can effectively be used as an electrode material of an electrochemical cell such as an electric double layer capacitor or a battery, which effectively utilizes plant waste and has a capacity equal to or higher than that of a conventional porous carbon material, and can also be used as an adsorbent. An object is to provide a method for producing a porous carbon material, a method for producing a porous activated carbon material, and a method for producing an electrode material.

In the method for producing a porous carbon material of the present embodiment, sugars derived from hemicellulose are first extracted from a plant biomass as a raw material. Hemicellulose is a generic term for polysaccharides excluding cellulose, which is contained in plant cell walls. Depending on the plant, the content of hemicellulose is about 10 to 30%. Xylan, the main component of hemicellulose, is a material of xylo-oligosaccharide, a sugar material with high added value.

The sugar-added material with high added value is extracted by a sugar extraction process, and the extracted sugar can be used as a food, pet or livestock feed. In addition, it is considered that by extracting the sugar in advance before the heat carbonization treatment, a porous carbon material in which the missing traces of the sugar develops a porous structure and has finer pores can be produced. The sugar component having a high added value can be effectively utilized by subjecting the plant to hot water treatment and extracting sugar in advance. In addition, since the water-soluble inorganic component is eluted, a homogeneous porous carbon material having few impurities and suppressing variation due to lots can be produced. In addition, it is thought that the ingredient to be ash is extracted together with sugar.

In the sugar extraction process, first, the plant biomass of the raw material is ground into three pieces. Plant biomass that can be used as a raw material is not particularly limited, for example, broad-leaved trees such as bamboo and buckthorn, and conifers such as cedar, rice straw, straw, rice husk, kenaf, and other organic substances. In this embodiment, it is preferable to use bamboo as a plant biomass from the viewpoint of countermeasures against bamboo damage.

The above-mentioned plant biomass is finely pulverized using a dry crusher, a wet crusher, a jet mill, and a bead mill. The particle size after pulverization is not particularly limited, but the sugar extraction process by the pressurized hydrothermal treatment is preferably several cm or less, more preferably 400 μm or less, and particularly preferably 50 μm or less. The smaller the particle size, the faster the rate of heat carbonization treatment and regeneration treatment using the sugar extraction rate by the hot water treatment or the residue thereof, and the faster the homogeneous porous carbon can be produced.

In this embodiment, it is preferable to perform sugar extraction by pressure hot water treatment. Pressurized hydrothermal treatment is a method that can safely and efficiently extract water-soluble sugars using only water, without using special chemicals such as acids, alkalis, and enzymes. By subjecting the hydrothermal treatment to pressurization, it is possible to extract water-soluble sugars derived from hemicellulose by decomposing hemicellulose contained in plants using only plant raw materials and water.

The pressurized hydrothermal treatment conditions are preferably performed at 140 or more and 230 or less, more preferably 160 or more and 220 or less, and particularly preferably 180 or more and 210 or less. Outside the above conditions, the effect of hydrothermal treatment is significantly reduced.

By performing the pressurized hydrothermal treatment above the lower limit, decomposition of hemicellulose proceeds, and the component of the hemicellulose constituent sugar can be efficiently extracted. At this time, part of the lignin is also eluted. Further, by performing the pressurized hydrothermal treatment below the upper limit, it is possible to suppress the incorporation of impurities due to decomposition of cellulose and the like, and to obtain a hemicellulose soluble product having high purity. By subjecting the pressurized hydrothermal treatment to the specific temperature conditions and extracting hemicellulose and some lignin, it is possible to prepare a porous carbon material in which these removal traces form a microporous structure and have a finer pore than the pore diameter of several nm or less. . In addition, the water-soluble inorganic component is eluted by the pressurized hydrothermal treatment, so that a homogeneous porous carbon material having few impurities and suppressing variations due to lots can be produced.

The pressurized hydrothermal treatment time may be appropriately adjusted depending on the treatment temperature and the size of the raw material, for example, the higher the temperature and the smaller the particle diameter, the shorter the time. In addition, the pressurized hydrothermal treatment time may be appropriately adjusted also by a treatment method such as a batch type, a phacocolator type, and a continuous type. For example, when hundreds of microns of bamboo particles are subjected to batch hot water treatment, the treatment time may be 180 to 30 minutes to 40 minutes. In the phacocalator type, treatment may be performed for 1 hour to 2 hours under the same conditions, but it is common for the phacolator type to have high yield and purity.

It is preferable that the pressure of the pressurized hot water treatment is "above the saturated water vapor pressure at the treatment temperature." The pressure is, for example, 180 to 1.0 MPa, 200 to 1.55 MPa or more, and in actual processing, the pressure vessel is adjusted so as not to fall below it by a method such as mechanical pressurization or filling with an inert gas.

The ratio of the bamboo crushed material to water is, for example, 0.1 w / v% or more and 30 w / v% or less as a weight concentration. This ratio may be appropriately adjusted depending on the particle diameter, but if it is 30 w / v% or less, the fluidity of the slurry becomes good. In the Pacolator type, since the same amount flows out by pouring hot water into the crushed crushed product, the concept of concentration does not fit, and becomes the filling amount for the reactor volume. Usually, it is sufficient to fill about 70% of the raw material powder of the reactor capacity in consideration of expansion.

After the sugar extraction process, the extracted sugar component and the solid residue produced by extracting the sugar are separated and recovered. The method of separation is not particularly limited, and any known method such as filtration or centrifugation may be used.

Examples of sugar components derived from hemicellulose recovered by the present embodiment include arabinose, glucose, xylose, fructose, xylobiose, xylotriose, xylotetraose, xylopentanose, and xylohexanose. . Among these, xylose can produce xyloligosaccharides, which are sugar materials with high added value, so that components in plant biomass can be efficiently utilized.

A water-soluble inorganic component such as potassium or sodium is eluted by a sugar extraction process, and a solid residue having high purity of the inorganic component can be obtained. Therefore, even in the same plant, it is possible to homogenize the variation of the inorganic components contained by the production area, region, age, etc. in a low amount. Thereby, the homogeneous porous carbon material with few impurities, such as ash, can be manufactured by suppressing the variation by lot in the case of heat carbonization treatment.

The solid residue recovered by the recovery process is heat carbonized to prepare a porous carbon material. In the present embodiment, it is preferable to perform the heat carbonization treatment at 500 or more. It is preferable because the amount of uncarbonized organic matter can be reduced by performing at 500 or more. It is thought that the higher the heating carbonization temperature, the larger the BET specific surface area after regeneration, and the larger the amount of substances to be adsorbed. The upper limit of the temperature of the heat carbonization treatment is not particularly limited, but examples thereof include 1500 or less, 900 or less, and 700 or less. When the temperature of the heat carbonization treatment exceeds 1500, the treatment temperature is preferably 1500 or less since it becomes expensive depending on the apparatus in order to improve the heat resistance of the treatment apparatus.

The time of the heat carbonization treatment step may be appropriately adjusted by an apparatus, for example, 0.5 hour or more and 5 hours or less is preferable, 1 hour or more and 2.5 hours or less are more preferable, and 1 hour or more and 2 hours or less are particularly preferable.

In this embodiment, it is thought that the pyrolysis motion changes because the composition ratio in the plant cell wall fluctuates by removing the sugar component derived from hemicellulose in advance. For this reason, it is presumed that a porous material with less impurities other than the case where the sugar component does not have a dependency on physical properties such as yield or specific surface area with respect to heating carbonization temperature or time can be produced.

In this embodiment, it is more preferable to perform the sugar extraction process at a temperature of 180 or more and 210 or less for 1 hour or more and 2 hours or less, and perform a heat carbonization treatment process at 500 or more.

By performing the sugar extraction step and the heat carbonization treatment step in a combination of the above conditions, the sugar component derived from hemicellulose can be efficiently extracted, and when used as an electrode material, a porous carbon material having a large capacity can be produced.

The description of the sugar extraction process, the recovery process, and the heating carbonization process in the method for producing the porous activated carbon material of the present invention includes the description of the sugar extraction process, the recovery process, and the heating carbonization process of the porous carbon material production method of the present invention. same.

The regeneration method is not particularly limited, and a gas regeneration method or a chemical regeneration method may be used.

The gas regeneration method is a method of obtaining activated carbon by contact reaction with water vapor, carbon dioxide, oxygen, etc. under high temperature. The chemical regeneration method is a method of impregnating the raw material after the heating and carbonization treatment with a known regenerating chemical and heating it in an inert gas atmosphere to cause dehydration and oxidation reaction of the regenerated chemical to obtain activated carbon. Examples of regenerative medicines include zinc chloride, sodium hydroxide, and potassium hydroxide. By regeneration, activated carbon can be produced and plant components can be efficiently utilized as electrodes of an electrochemical cell.

The electrode material manufacturing method of the present invention includes a sugar extraction process for extracting hemicellulose-derived sugar from a plant biomass, a recovery process for recovering solid residues generated by extracting the sugar, a heat carbonization treatment process for heating and carbonizing the solid residue, and the And a regeneration step of regenerating the porous carbon material obtained by heat carbonization treatment.

In the electrode material manufacturing method of the present invention, descriptions of the sugar extraction process, the recovery process, the heating carbonization treatment process, and the regeneration process are described in the method of manufacturing the porous activated carbon material of the present invention, the sugar extraction process, the recovery process, the heating carbonization process, and the regeneration. Same as the description of the process.

Further, the obtained porous activated carbon material, a conductive aid and a binder can be mixed, and an electrode material can be produced.

As a binder, a thermoplastic resin can be used. Examples of the thermoplastic resin include polyvinylidene fluoride (PVdF.), Polytetrafluoroethylene (PTFE), ethylene tetrafluoride propylene hexafluoride vinylidene fluoride copolymer, propylene hexafluoride vinylidene fluoride copolymer, and ethylene perfluoride tetrafluoride. Fluorine resins such as rovinyl ether copolymers; And polyolefin resins such as polyethylene and polypropylene. Examples of the conductive aid include those having high conductivity and no corrosion with respect to the electrolyte used such as graphite, acetylene black, and ketjen black.

The porous carbon material produced by the method for producing a porous carbon material of the present invention has fine pores having a pore diameter of several nm or less. The specific surface area calculated by the BET method is 20 m ² / g or more, 300 m ² / g or more, and 600 m ² / g or more depending on the heating conditions.

Further, the porous activated carbon material produced by the method for producing a porous activated carbon material of the present invention has fine pores having a pore diameter of several nm or less. In addition, according to a specific surface area of 1000m ² / g or more, the heating conditions are calculated by the BET method is ^{2000m 2 / g ~ 2800m 2 /} g. This specific surface area is a value suitable for a carbon material for an electric double layer capacitor electrode from the viewpoint of improving the capacitance. For this reason, according to the present invention, a carbon material that can be suitably used as an electrode material can be produced using plant biomass such as bamboo.

In addition, the plant biomass may be irradiated with radiation during the recovery process or prior to the heat carbonization treatment process.

The radiation was irradiated with gamma rays until the dose reached 2 kGy.

Those skilled in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above.

Claims (8)

A method for producing a porous carbon material, comprising a sugar extraction process for extracting hemicellulose-derived sugar from a plant biomass, a recovery process for recovering solid residues generated by extracting the sugar, and a heating carbonization process for heating and solidifying the solid residue. The method of claim 1, wherein the sugar extraction process is a pressurized hydrothermal treatment process. The method of claim 1, wherein the pressurized hydrothermal treatment process is performed at 160 ° C or higher and 220 ° C or lower. The method of claim 1, wherein the heat carbonization treatment step is performed at 500 ° C or higher. The method of claim 1, wherein the plant biomass is Kenaf. The method according to claim 1, wherein ultrasonic heating using a metal derivative is performed in parallel during the heating carbonization process. The method of claim 1, wherein the plant biomass is irradiated with radiation during the recovery process or prior to the heat carbonization process. A sugar extraction process for extracting hemicellulose-derived sugar from plant biomass, a recovery process for recovering solid residues generated by extracting the sugar, a heating carbonization process for heating and carbonizing the solid residue, and a porous carbon obtained by the heating carbonization process A method for producing a porous activated carbon material, comprising a regeneration step of regenerating the material.