Method for manufacturing porous carbon dioxide absorbent material using lignin

Abstract

A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin is provided, wherein, when synthesizing a porous carbon dioxide adsorption material, the carbon dioxide adsorption capacity of the adsorption material can be improved by adding ethylenediamine to lignin to amine it, nitrogen-doped reduced graphene oxide can be easily prepared using amine, a highly porous carbon dioxide adsorption material with improved pore activation can be manufactured by introducing magnesium metal in a magnesium chloride (MgCl2) solution to improve the basicity of the adsorption material, and a highly porous carbon dioxide adsorption material having metal-introduced and nitrogen-doped reduced graphene oxide as the final product can be economically manufactured by introducing a metal into amine-functionalized lignin and then carbonizing it at a low temperature.

Description

Technology Field

[0001] The present invention relates to the manufacture of a porous carbon dioxide adsorption material, and more specifically, to a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, wherein ethylenediamine is added to lignin to amine it during the synthesis of the porous carbon dioxide adsorption material, and a metal is introduced to activate the pores. Background Technology

[0002] Generally, adsorption refers to the phenomenon in which one or more components accumulate (enrich) between two phases. An example is the adsorption phenomenon occurring on a solid surface exposed to a gas or liquid.

[0003] In this context, a substance having a surface where adsorption occurs is called an adsorbent, and the substance adsorbed onto that surface is called an adsorbate.

[0004] The adsorption of adsorbents by such adsorbents can include both physical adsorption (physiosorption), which does not involve chemical bonding, and chemical adsorption (chemiosorption), which involves chemical bonding.

[0005] Some adsorbents (adsorbent materials) are used as desiccants, catalysts, and catalytic supports, and

[0006] Some adsorbents are used for purposes such as gas separation or accumulation, liquid purification, controlled drug delivery, pollution control, or respiratory protection.

[0007] For example, activated carbon is one of the most widely used adsorbents in industry and refers to a porous material in which carbon-rich substances have been chemically or physically activated.

[0008] Typically, activated carbon is produced by incompletely burning coal or fiber-rich biomass under anaerobic conditions. It was originally used to decolorize molasses, and in modern times, it is used for various purposes in many industries, such as the separation and purification of chemicals and the deodorization of odor components.

[0009] These activated carbons uniquely possess both physical and chemical adsorption properties, so they can adsorb not only hydrophobic nonionic organic substances but also ionic organic acids.

[0010] Meanwhile, lignocellulosic biomass contains cellulose, hemicellulose, and lignin as structural components, along with phospholipids, proteins, small amounts of alkaloids, and various inorganic salts that constituted living cells.

[0011] At this time, cellulose, a glucose polymer, can be converted into glucose through pretreatment and saccharification, and since this glucose can be converted into bioalcohols such as bioethanol and various organic acids such as lactic acid and succinic acid by industrial microorganisms such as yeast and E. coli, it has established itself as a renewable resource capable of replacing petroleum products.

[0012] Technology for producing second-generation bioethanol using such lignocellulosic biomass as a raw material has already been commercialized in the United States, Canada, Brazil, and Europe, and produces hemicellulose-containing products or fermentation residues as byproducts.

[0013] In addition, lignocellulosic biomass can be used as a raw material to produce lignocellulosic sugars primarily composed of glucose or xylose by enzymatically hydrolyzing the structural components, cellulose or hemicellulose; the sugar products produced in this way can be used as fermentable sugar, edible sugar, or adhesives for feed production.

[0014] The processes for manufacturing such lignocellulosic sugars mostly discharge saccharification residues containing lignin as a byproduct. The surface characteristics of these lignin-containing saccharification residues vary depending on the pretreatment and saccharification methods.

[0015] For example, when enzymatic saccharification is performed by pretreatment with an alkaline solvent such as sodium hydroxide or ammonia water, the saccharification residue is hydrophilic.

[0016] On the other hand, the saccharification residue remaining as an insoluble solid after enzymatic or acid saccharification following acid or hydrothermal pretreatment has slight hydrophobicity; therefore, in the case of enzymatic saccharification, it may irreversibly adsorb enzyme proteins during saccharification, thereby causing a decrease in enzyme activity.

[0017] In addition, the components of plant biomass can generally be broadly classified into three parts: cellulose, hemicellulose, and lignin.

[0018] Among these, the lignin component accounts for 20% to 30% of the composition, depending on the type of tree, and is chemically C18H 24 O 11 and C 40 H 45 O 18 It is known as a component of Sai.

[0019] In addition, when producing alcohol or other useful compounds using plant biomass, cellulose and hemicellulose are mainly used, and lignin components, which are difficult to decompose and difficult to process chemically, are generally disposed of as waste or treated as fuel.

[0020] In addition, even when using wood to manufacture pulp, the cellulose and hemicellulose components are utilized as components of the pulp, but the lignin components are separately removed and discharged as waste, which is generally called black liquor, and is treated as fuel by evaporating the water contained in it.

[0021] At this time, as a method for manufacturing a carbonaceous adsorbent by separating lignin from black liquor, amorphous powdered activated carbon is produced by separating and solidifying the lignin, and then activating it using various physical and chemical methods to increase the specific surface area.

[0022] Meanwhile, as prior art, Japanese registered patent No. 5,062,593 discloses an invention titled "Carbon fine particles made of lignin and a method for manufacturing the same."

[0023] Specifically, in the case of carbon microparticles made from lignin according to conventional technology, the lignin is liquefied and the liquefied lignin is dried,

[0024] A high surface area adsorption material is disclosed by producing lignin microparticles by spraying an aqueous sodium hydroxide solution, and then subjecting the lignin microparticles to a carbonization process by heat-treating and decomposing them under nitrogen gas.

[0025] Meanwhile, as prior art related to high specific surface area activated carbon made from lignin, Japanese Patent No. 5,495,208 discloses an invention titled "High specific surface area activated carbon made from lignin and adsorbent for lower alcohols containing the same."

[0026] Specifically, in the case of high specific surface area activated carbon using lignin as a raw material according to conventional technology, potassium carbonate is mixed with lignin and dried,

[0027] After placing it inside a ceramic reaction tube and subjecting it to a heat treatment and carbonization process under a nitrogen environment,

[0028] A method for manufacturing high-surface-area lignin-adsorbing activated carbon is disclosed, which is washed with distilled water and then dried again.

[0029] Meanwhile, as prior art related to a method for manufacturing activated carbon using lignin, Korean Patent Registration No. 10-1585431 discloses an invention titled "Method for manufacturing activated carbon using lignin generated in a pulp manufacturing process and activated carbon manufactured therefrom."

[0030] Specifically, in the case of a method for manufacturing activated carbon using lignin according to conventional technology, liquid lignin is obtained by heating lignin, and then the liquid lignin is mixed with ethyl cellulose, a pore-forming agent,

[0031] The present invention discloses a method for producing lignin activated carbon by heating a mixture of liquid lignin and ethyl cellulose under nitrogen gas, wherein the optimal specific surface area of ​​the activated carbon is produced by mixing ethyl cellulose, which is a pore-forming agent, and then undergoing a carbonization process with nitrogen gas.

[0032] Meanwhile, as prior art related to the manufacture of porous carbon materials, Korean registered patent number 10-1281766 discloses an invention titled "Porous carbon material and method of manufacturing the same," which will be explained with reference to FIG. 1.

[0033] FIG. 1 is a drawing showing a method for manufacturing a porous carbon material according to conventional technology.

[0034] Referring to FIG. 1, a method for manufacturing a porous carbon material according to the prior art first provides lignin.

[0035] Next, the lignin is melted at a temperature of 150 to 300°C, cooled, and then ground into a uniform size.

[0036] Next, the crushed lignin is heated in a liquid at a temperature of 150 to 300°C while stirring to form a liquid mixture containing spherical granulated lignin. At this time, the liquid used may be at least one selected from water, silicone oil, glycerin, heat transfer oil, vegetable oil, mineral oil, and synthetic oil.

[0037] Next, the liquid mixture is cooled to a temperature below 150°C to separate the solidified lignin particles while maintaining their spherical shape.

[0038] Next, the separated lignin particles are stabilized by heat treatment at a temperature of 200 to 350°C for 10 minutes to 5 hours in an air atmosphere.

[0039] Next, a porous carbon material is manufactured by activating stabilized lignin particles.

[0040] According to a method for manufacturing porous carbon materials based on conventional technology, high-value porous carbon materials are manufactured using lignin generated from biomass byproducts as a raw material, which can be used as porous adsorbents with increased packing density and excellent mechanical strength.

[0041] Meanwhile, Korean Patent Publication No. 2022-136816, which relates to an adsorbent with lignin as the main component, discloses an invention titled "Adsorbent with lignin as the main component and method for manufacturing the same," which will be explained with reference to FIG. 2.

[0042] FIG. 2 is a diagram briefly illustrating a method for manufacturing an adsorbent with lignin as the main component according to conventional technology.

[0043] Referring to FIG. 2, a method for manufacturing an adsorbent with lignin as the main component according to conventional technology first pretreats woody biomass using a hydrothermal or acid catalyst.

[0044] Next, the pre-treated lignocellulosic biomass is saccharified using enzymes or acid.

[0045] Next, the solid saccharification residue separated from the saccharified material obtained from the biomass saccharification stage is produced through a solid-liquid separation process.

[0046] Next, the saccharification residue is repeatedly washed with water or water and an organic solvent to produce a saccharification residue from which soluble substances have been removed.

[0047] Next, the saccharification residue from which water-soluble substances have been removed is dried.

[0048] According to a method for manufacturing an adsorbent composed mainly of lignin according to conventional technology, an adsorbent composed mainly of lignin, which has strong adsorption properties for hydrophobic chemicals, is

[0049] It is very suitable for the separation and purification of biomass-derived sugar products because it uses plant biomass as a raw material, has a very high lignin content and a large surface area, easily adsorbs many types of chemicals that are hydrophobic rather than sugars (sugar or saccharides), while hardly adsorbing sugars.

[0050] In addition, it effectively adsorbs chemicals that are soluble in water but relatively hydrophobic, such as phenol, so it can be used as an economical adsorbent for chemical reaction solutions or wastewater treatment.

[0051] Meanwhile, according to conventional technology, it is known that in order to manufacture reduction graphene oxide (rGO), graphene oxide is first manufactured and then reduction is carried out.

[0052] In addition, according to conventional technology, it is known that heat of about 1000°C must be applied to reduce graphene oxide.

[0053] In addition, it is known that conventional methods for producing nitrogen-doped carbon using lignin typically involve adding chitosan or urea to the lignin and carbonizing them together. Prior art literature

[0054] Korean Registered Patent No. 10-1281766 (Registration Date: June 20, 2013), Title of Invention: "Porous carbon material and method for manufacturing the same" Korean Registered Patent No. 10-1585431 (Registration Date: January 8, 2016), Title of Invention: "Method for manufacturing activated carbon using lignin generated in a pulp manufacturing process and activated carbon manufactured therefrom" Korean Published Patent No. 2013-46231 (Publication Date: May 7, 2013), Title of Invention: "Porous activated carbon using black liquor as a raw material and method for manufacturing the same" Japanese Registered Patent No. 5,495,208 (Registration Date: March 14, 2014), Title of Invention: "High specific surface area activated carbon using lignin as a raw material and adsorbent for lower alcohols containing the same" Korean Published Patent No. Japanese Patent No. 2022-136816 (Publication Date: October 11, 2022), Title of Invention: "Adsorbent with Lignin as Main Component and Method for Manufacturing the Same" Japanese Patent No. 5,062,593 (Registration Date: August 17, 2012), Title of Invention: "Carbon Microparticles Using Lignin as Raw Material and Method for Manufacturing the Same" The problem to be solved

[0055] The technical objective of the present invention to solve the aforementioned problems is to provide a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, which can improve the carbon dioxide adsorption capacity of the adsorption material by adding ethylenediamine to lignin and amination it during the synthesis of the porous carbon dioxide adsorption material, and can easily manufacture nitrogen-doped reduced graphene oxide using amine.

[0056] Another technical objective of the present invention is to provide a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, which can produce a highly porous carbon dioxide adsorption material with improved pore activation by introducing magnesium metal into a magnesium chloride (MgCl2) solution to enhance the basicity of the adsorption material.

[0057] Another technical objective of the present invention is to provide a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, which can economically produce a highly porous carbon dioxide adsorption material having a metal-introduced and nitrogen-doped reduced graphene oxide as the final product by introducing a metal into amine-functionalized lignin and then carbonizing it at a low temperature. means of solving the problem

[0058] As a means to achieve the aforementioned technical problem, a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to the present invention comprises: a) amination of alkali lignin to form amine-functionalized lignin in order to improve the carbon dioxide adsorption capacity of the adsorption material; b) a step of placing the amine-functionalized lignin into a magnesium chloride solution and introducing a metal into the lignin to activate the pores of the carbon dioxide adsorption material; and c) a step of forming a porous carbon dioxide adsorption material through carbonization of the metal-introduced lignin; wherein the porous carbon dioxide adsorption material is formed as a final product of metal-introduced and nitrogen-doped reduced graphene oxide by introducing a metal into amine-functionalized lignin and then carbonizing it; wherein step b) is performed by placing the amine-functionalized lignin into a 1M magnesium chloride (MgCl2) solution and stirring it at 50 to 65°C for 1 hour 30 minutes to 2 hours 30 minutes, and then further stirring it at room temperature for 20 to 24 hours; and step c) is performed by raising the metal-introduced lignin to 550 to 650°C at a heating rate of 2.5°C / min in a nitrogen gas atmosphere and then maintaining it for 1 hour to 1 hour 30 minutes to carbonize it. Effects of the invention

[0059] According to the present invention, when synthesizing a porous carbon dioxide adsorption material, the carbon dioxide adsorption capacity of the adsorption material can be improved by adding ethylenediamine to lignin to amine it, and nitrogen-doped reduced graphene oxide can be easily prepared using an amine.

[0060] According to the present invention, a highly porous carbon dioxide adsorption material can be produced by introducing magnesium metal in a magnesium chloride (MgCl2) solution to improve the basicity of the adsorption material, thereby promoting pore activation.

[0061] According to the present invention, by introducing a metal into amine-functionalized lignin and then carbonizing it at a low temperature, a highly porous carbon dioxide adsorption material having a metal-introduced and nitrogen-doped reduced graphene oxide as the final product can be economically produced. Brief explanation of the drawing

[0062] FIG. 1 is a drawing showing a method for manufacturing a porous carbon material according to conventional technology. FIG. 2 is a diagram briefly illustrating a method for manufacturing an adsorbent with lignin as the main component according to conventional technology. FIG. 3 is a schematic flowchart illustrating a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention. FIG. 4 is a flowchart specifically illustrating the amination process of alkali lignin in a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention. FIG. 5 is a flowchart specifically illustrating the process of introducing magnesium chloride metal in a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention. FIG. 6 is a flowchart specifically illustrating the carbonization process in a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention. Figure 7 is a diagram showing the specific surface area analysis (BET) results of an adsorption material produced by the method for producing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention. FIG. 8 is a diagram showing the carbon dioxide adsorption results of an adsorption material manufactured by a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention. FIGS. 9a, 9b, and 9c illustrate a carbonization process according to a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention. Specific details for implementing the invention

[0063] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0064] Throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0065] [Method for manufacturing porous carbon dioxide adsorption material using lignin]

[0066] FIG. 3 is a schematic flowchart illustrating a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention, and FIG. 9a, FIG. 9b, and FIG. 9c illustrate a carbonization process according to the method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention.

[0067] Referring to FIG. 3, a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention is,

[0068] First, alkali lignin is aminized to form amine-functionalized lignin in order to improve the carbon dioxide adsorption capacity of the adsorption material (S110).

[0069] Next, to activate the pores of the carbon dioxide adsorption material, the amine-functionalized lignin is placed in a magnesium chloride solution and a metal is introduced (S120).

[0070] Next, a porous carbon dioxide adsorption material is formed through the carbonization of the lignin into which the metal is introduced (S130).

[0071] Accordingly, with reference to FIGS. 9a, 9b, and 9c, the porous carbon dioxide adsorption material is formed by introducing a metal into amine-functionalized lignin and then carbonizing it, thereby forming metal-introduced and nitrogen-doped reduced graphine oxide (MgO / N-doped reduction Graphine Oxide: MgO / N-rGO) as the final product.

[0072] According to the method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention, when synthesizing a porous carbon dioxide adsorption material, ethylenediamine is added to lignin to amine it, thereby improving the carbon dioxide adsorption capacity of the adsorption material, and nitrogen-doped reduced graphene oxide can be easily manufactured using amine.

[0073] According to the method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention, a highly porous carbon dioxide adsorption material with improved pore activation can be manufactured by introducing magnesium metal in a magnesium chloride (MgCl2) solution to improve the basicity of the adsorption material.

[0074] According to the method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention, by introducing a metal into amine-functionalized lignin and then carbonizing it at a low temperature, a highly porous carbon dioxide adsorption material having reduced graphene oxide with introduced metal and nitrogen doped as the final product can be economically manufactured.

[0075] Specifically, FIG. 4 is a flowchart specifically illustrating the amination process of alkali lignin in a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention.

[0076] Referring to FIG. 4, in the method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention, the amination process of alkali lignin is,

[0077] First, to amine the alkali lignin, 10 g of alkali lignin is added to a 0.4 M sodium hydroxide (NaOH) solution and stirred for at least 3 hours until completely dissolved (S111).

[0078] That is, since lignin is not sufficiently dissolved in the sodium hydroxide (NaOH) solution when stirred for less than 3 hours, it is stirred for more than 3 hours.

[0079] In addition, since the binding structure of lignin is not sufficiently loosened, making efficient amine introduction difficult, the lignin must be completely dissolved.

[0080] In addition, lignin is dissolved using alkaline solvents, and sodium hydroxide (NaOH) solution is mainly used because it is more economical than other solvents.

[0081] In addition, since lignin dissolves in a sodium hydroxide (NaOH) solution with a pH of 12 or higher, lignin can be sufficiently dissolved with 0.4 M sodium hydroxide (NaOH) with a pH of about 13.

[0082] Next, 10 ml of formaldehyde and 10 ml of ethylenediamine are added to the sodium hydroxide solution in which the alkali lignin is dissolved, for example, and stirred at 65 to 75°C for 6 to 7 hours (S112).

[0083] Here, the reason for adopting the above formaldehyde and ethylenediamine is to induce a Mannich reaction to introduce amines into lignin.

[0084] Specifically, the Mannich reaction is a ternary organic reaction in organic chemistry involving the aminoalkylation of an acidic proton next to a carbonyl group (C=O) by formaldehyde (H-CHO) and a primary or secondary amine (-NH2) or ammonia (NH3).

[0085] The final product is a β-amino-carbonyl compound, also known as a Mannich base. The reaction between an aldimine and an α-methylene carbonyl is also considered a Mannich reaction because it is formed between these amines and aldehydes.

[0086] In addition, ethylenediamine is selected among the types of amines because ethylenediamine is composed of two primary amines (C2H4(NH2)2).

[0087] Specifically, in the method for synthesizing a porous carbon dioxide adsorption material according to an embodiment of the present invention, chelate bonding between an amine and magnesium is induced to introduce magnesium into the adsorption material, and ethylenediamine is adopted because the two amine groups introduced into the lignin structure can bond with a larger amount of magnesium.

[0088] In addition, the largest amount of amine can be introduced when stirring for amine introduction at the corresponding temperature is for 6 to 7 hours.

[0089] Next, a 3% hydrochloric acid solution is added to the stirred mixture to adjust the pH until a solid is produced (S113).

[0090] Here, the pH of the mixture can be adjusted to 6.0 to 6.4, preferably 6.2, by the 3% hydrochloric acid solution.

[0091] Next, when solids are produced, the solids are washed with distilled water, and the solids produced by separating solids and liquids by centrifugation are completely dried in a drying oven at 70 to 90°C (S114).

[0092] Here, since the color of lignin turns black in a drying oven at 90°C or higher, it is desirable to completely dry it in a drying oven at 70°C to 90°C.

[0093] Meanwhile, FIG. 5 is a flowchart specifically illustrating the process of introducing magnesium chloride metal in a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention.

[0094] Referring to FIG. 5, the process of introducing magnesium chloride metal in the method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention is,

[0095] First, 5g of completely dried amine-functionalized lignin is added to a 1M magnesium chloride (MgCl2) solution and stirred at 50 to 65°C for 1 hour 30 minutes to 2 hours 30 minutes (S121).

[0096] At this time, heat at a low temperature of 50 to 65°C is applied to accelerate the introduction of the metal magnesium (Mg) into the adsorption material.

[0097] In addition, when stirring for more than 2 hours and 30 minutes, more magnesium (Mg) than necessary is introduced, so even if the adsorption material is manufactured under the same carbonation conditions, it shows a low BET and the amount of carbon dioxide adsorbed at room temperature may decrease.

[0098] In other words, due to the excess magnesium (Mg) present on the surface of the adsorption material, the pore activation of lignin may not be efficiently achieved during the carbonization process.

[0099] As a result, the interaction between carbon dioxide and the lignin-based material located at the center of the material does not occur smoothly, and

[0100] Carbon dioxide adsorption reactions can occur primarily through chemisorption, which takes place at high temperatures, rather than physisorption, which mainly occurs at room temperature.

[0101] Therefore, in the case of the porous carbon dioxide adsorption material according to the embodiment of the present invention, since it is intended to generate carbon dioxide adsorption at room temperature, an amount of magnesium (Mg) greater than necessary may result in unsuitable outcomes.

[0102] Next, the mixture is further stirred at room temperature for 20 to 24 hours (S122).

[0103] In other words, the reason for additional stirring at room temperature for 20 to 24 hours is to stabilize the magnesium chelated with the amine.

[0104] Next, the solid is separated by centrifugation and then dried in a drying oven at 70~90℃ (S123).

[0105] In other words, since the color of lignin changes in a drying oven of 90°C or higher, it is preferable to dry it in a drying oven of 70°C to 90°C.

[0106] Meanwhile, FIG. 6 is a flowchart specifically illustrating the carbonization process in a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention.

[0107] Referring to FIG. 6, in the method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention, the carbonization process is,

[0108] First, the above solid is heated to 550~650℃ with a heating speed increasing to 2.5℃ / min in a nitrogen gas flow, and then the temperature is maintained for 1~1 hour 30 minutes to form reduced graphene oxide with metal introduced and nitrogen doped (S131).

[0109] Specifically, it was confirmed that at temperatures below 550°C, carbonization of lignin does not occur and the chloride of magnesium chloride (MgCl2) remains.

[0110] In addition, the oxidation of magnesium (Mg) in the final product to the desired level did not proceed smoothly.

[0111] In addition, at temperatures above 650°C, the balance between magnesium chloride (MgO) and magnesium hydroxide (Mg(OH)2) in the final adsorption material is not achieved, and the carbon dioxide adsorption performance may decrease due to excessive magnesium oxide.

[0112] Next, the metal-introduced and nitrogen-doped reduced graphene oxide is washed with at least 25% ethanol and then further washed with distilled water (S132).

[0113] Next, the reduced graphene oxide to which the metal has been introduced and which is nitrogen-doped is completely dried in a drying oven at 70 to 90°C to form a porous carbon dioxide adsorption material (S133).

[0114] That is, complete drying was carried out at 70~90℃ to prevent further changes in the properties of the adsorption material.

[0115] Meanwhile, Fig. 7 is a diagram showing the specific surface area analysis (BET) results of an adsorption material produced by the method for producing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention.

[0116] The specific surface area analysis (BET) results of the adsorption material prepared by the method for preparing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention are,

[0117] As shown in Figure 7, results were obtained for MgO / N-rGO at 818 m² / g, N-rGO at 0.8391 m² / g, and rGO at 0.5302 m² / g.

[0118] This is a porous carbon dioxide adsorption material prepared by the method for preparing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention, and it can be seen that in the case of MgO / N-rGO, pore activation proceeded compared to other materials due to the influence of magnesium chloride (MgCl2).

[0119] Through this, it can be seen that a highly porous material was manufactured to enhance the physical adsorption capacity of carbon dioxide (CO2).

[0120] Meanwhile, Fig. 8 is a diagram showing the carbon dioxide adsorption results of an adsorption material manufactured by a method for manufacturing a porous carbon dioxide adsorption material using lignin according to an embodiment of the present invention.

[0121] As shown in Fig. 8, the MgO / N-rGO adsorption material prepared by the method for preparing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention showed a carbon dioxide adsorption amount of 3.02 mmol / g at room temperature, and the graph indicates that physical adsorption mainly occurred.

[0122] In other words, when designing an adsorption material to increase the amount of carbon dioxide adsorbed, magnesium can be introduced to increase the affinity with carbon dioxide, and the basicity of the adsorption material can also be increased by introducing nitrogen.

[0123] At this time, to increase the interaction area between the adsorption material and carbon dioxide, the bonding of carbon materials is induced to produce a structure in the form of reduced graphene oxide.

[0124] In addition, magnesium chloride can be used to promote the introduction of magnesium and the creation of pores on the surface of lignin.

[0125] Therefore, a porous carbon dioxide adsorption material can be easily manufactured by the method for manufacturing a porous carbon dioxide adsorption material utilizing lignin according to an embodiment of the present invention.

[0126] As mentioned above, according to conventional technology, to produce reduction graphene oxide (rGO), graphene oxide is first produced, and then reduction is carried out.

[0127] However, in the case of the porous carbon dioxide adsorption material according to the embodiment of the present invention, reduced graphene oxide (rGO) can be produced from raw lignin in one step.

[0128] In addition, according to conventional technology, heat of about 1000°C must be applied to reduce graphene oxide, but

[0129] In the case of the porous carbon dioxide adsorption material according to the embodiment of the present invention, graphene oxide can be economically reduced by applying heat of 500 to 650°C for about 1 hour to 1 hour 30 minutes.

[0130] In addition, magnesium chloride (MgCl2) is added during the metal introduction process to introduce magnesium (Mg) and activate pores, and

[0131] The magnesium chloride (MgCl2) introduced in this way creates lignin pores during the carbonization process, allowing magnesium oxide (MgO) and magnesium hydroxide (Mg(OH)2) to be present in the final product.

[0132] In addition, conventional methods for producing nitrogen-doped carbon using lignin typically involve adding chitosan or urea to the lignin and carbonizing them together, but

[0133] In the case of the porous carbon dioxide adsorption material according to the embodiment of the present invention, nitrogen-doped reduced graphene oxide can be easily prepared using an amine.

[0134] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0135] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

Claims

Claim 1 a) a step of forming amine-functionalized lignin by amination of alkali lignin to improve the carbon dioxide adsorption capacity of the adsorption material; b) a step of placing the amine-functionalized lignin into a magnesium chloride (MgCl2) solution and introducing a metal into the lignin to activate the pores of the carbon dioxide adsorption material; and c) a step of forming a porous carbon dioxide absorbent material through carbonization of the metal-introduced lignin; wherein the porous carbon dioxide absorbent material is formed as a final product of metal-introduced and nitrogen-doped reduced graphine oxide (MgO / N-rGO) by introducing a metal into amine-functionalized lignin and then carbonizing it; wherein step b) is performed by placing the amine-functionalized lignin into a 1M magnesium chloride (MgCl2) solution and stirring at 50 to 65°C for 1 hour 30 minutes to 2 hours 30 minutes, followed by additional stirring at room temperature for 20 to 24 hours; and step c) is performed by heating the metal-introduced lignin to 550 to 650°C at a heating rate of 2.5°C / min in a nitrogen gas atmosphere, followed by 1 hour to 1 hour 30 minutes Method for manufacturing a porous carbon dioxide adsorption material utilizing lignin that is maintained and carbonized over time. Claim 2 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, wherein step a) comprises: a-1) a step of adding a predetermined amount of alkali lignin to a 0.4M sodium hydroxide solution for the amination of the alkali lignin and stirring for a predetermined time or longer until completely dissolved; a-2) a step of stirring a mixture in which a predetermined amount of formaldehyde and a predetermined amount of ethylenediamine are each added to the sodium hydroxide solution in which the alkali lignin is dissolved, at a predetermined temperature for a predetermined time; a-3) a step of adding a 3% hydrochloric acid solution to the stirred mixture to adjust the pH until a solid is generated; and a-4) a step of washing the solid with distilled water, and then completely drying the solid generated by solid-liquid separation by centrifugation. Claim 3 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in step a-1) above, the 0.4M sodium hydroxide solution comprises an alkaline solvent capable of completely dissolving the lignin and having a pH of 13. Claim 4 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in the second paragraph, the stirring time in step a-1) is at least 3 hours. Claim 5 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in step a-2), the formaldehyde and ethylenediamine induce a Mannich reaction to introduce an amine into the lignin. Claim 6 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in paragraph 2, the mixture of step a-2) is stirred at a temperature of 65 to 75°C for 6 to 7 hours. Claim 7 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in step a-3) of claim 2, the pH of the mixture is adjusted to 6.0 to 6.4 by a 3% hydrochloric acid solution. Claim 8 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in step a-4) above, the solid is completely dried in a drying oven at 70 to 90°C. Claim 9 In claim 2, the step b) comprises: b-1) a step of stirring a mixture in which a predetermined amount of the completely dried amine-functionalized lignin is added to a 1M magnesium chloride solution; b-2) a step of further stirring the mixture at room temperature for a predetermined time; and b-3) a step of separating the solid by centrifugation and drying, thereby forming a method for manufacturing a porous carbon dioxide adsorption material utilizing lignin. Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in step b-3) above, the material is dried in a drying oven at 70 to 90°C to prevent the color of the lignin from changing. Claim 14 In claim 9, the step c) comprises: c-1) carbonizing the solid material in a nitrogen gas flow at a predetermined heating rate and maintaining the temperature for a predetermined time once a predetermined temperature is reached to form metal-introduced and nitrogen-doped reduced graphene oxide; c-2) washing the metal-introduced and nitrogen-doped reduced graphene oxide with at least 25% ethanol and additionally washing with distilled water; and c-3) completely drying the metal-introduced and nitrogen-doped reduced graphene oxide to form a porous carbon dioxide adsorption material. Claim 15 delete Claim 16 delete Claim 17 A method for manufacturing a porous carbon dioxide adsorption material utilizing lignin, characterized in that, in step c-3) above, the reduced graphene oxide into which the metal is introduced and which is nitrogen-doped is completely dried in a drying oven at 70 to 90°C to form a porous carbon dioxide adsorption material as the final product. Claim 18 A porous carbon dioxide adsorption material produced by a method for producing a porous carbon dioxide adsorption material utilizing lignin according to any one of claims 1 to 9, 13, 14 and 17.

Images