Patent Application
20240247201
The present disclosure relates to a method of generating high-purity hydrogen from waste plastic without producing carbon dioxide.
The present disclosure was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2022R1A2C2010744); and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2020R1A5A1019631).
Today, mass-produced plastics are indiscriminately discarded without proper recycling or treatment, causing environmental pollution. Methods of treating waste plastic include incineration, pyrolysis, and gasification. However, incineration of waste plastic generates dioxin, which is a harmful substance, and carbon dioxide, which is a cause of global warming, during burning. In the case of pyrolysis (emulsification), it is easy to recover wax, olefin-based polymers, and monomers, but it is difficult to recover them in high purity, when non-olefin-based waste plastic is also present in the waste mixtures. Therefore, in recent years, a gasification process that facilitates the treatment of mixed waste plastic and generates fewer air pollutants has been actively developed.
During a steam reforming reaction, a gasification process, hydrocarbon or a hydrocarbon compound containing oxygen is allowed to react with steam to generate hydrogen, and during this reaction, feedstock is brought into contact with water under high temperature conditions and CO, CO2 and H2 gases are generated according to the following reaction scheme:
The steam reforming reaction is endothermic and thus requires heat, and the process needs to be performed at a high temperature in order to cause the reaction. Accordingly, there is a problem of high energy cost. Also, CO and CO2 gases are generated as by-products in addition to hydrogen. Accordingly, there is a need for an additional process for separating high-purity hydrogen.
The present disclosure provides a method of generating high-purity hydrogen from waste plastic without producing carbon dioxide.
However, problems to be solved by the present disclosure are not limited to the above-described problems, and although not described herein, other problems to be solved by the present disclosure can be clearly understood by those skilled in the art from the following descriptions.
A first aspect of the present disclosure provides a method of generating hydrogen using plastic containing oxygen, and the method includes: subjecting the plastic containing oxygen to a thermal treatment reaction with hydroxide and water vapor to obtain hydrogen, and an amount of generated CO2 is about 10 mol % or less of the total generated gas.
A second aspect of the present disclosure provides a method of generating hydrogen using plastic not containing oxygen, and the method includes: thermally oxidizing the plastic not containing oxygen to obtain thermally oxidized plastic; and subjecting the thermally oxidized plastic to a thermal treatment reaction with hydroxide and water vapor to obtain hydrogen.
In the method of generating hydrogen according to the embodiments of the present disclosure, hydroxides included as reactants increase the amount and purity of the generated hydrogen, lower the reaction temperature appropriate for hydrogen production, and significantly decrease the amount of generated carbon dioxide.
In the method of generating hydrogen according to the embodiments of the present disclosure, plastic containing oxygen is subjected to a thermal treatment reaction, and thus, carbon monoxide is generated during the reaction. Since the generated carbon monoxide and steam together form hydrogen, the amount of generated hydrogen is increased.
The method of generating hydrogen according to the embodiments of the present disclosure is performed in a low process temperature range at a high hydrogen production rate as compared to a conventional steam reforming process of plastic.
The method of generating hydrogen according to the embodiments of the present disclosure generates high-purity hydrogen as compared to the conventional steam reforming process.
In the method of generating hydrogen according to the embodiments of the present disclosure, carbon and oxygen contained in the reactants are captured in the form of solid carbonate or bicarbonate, which results in a remarkably low production amount of carbon dioxide.
The method of generating hydrogen according to the embodiments of the present disclosure uses waste plastic and requires little or extremely low raw material procurement cost and thus can economically produce hydrogen. In particular, as waste plastic, polyethylene terephthalate (PET) is one of the most widely used plastics in everyday life and can be procured in large quantities, and poly(methyl methacrylate) (PMMA) is used for specific purposes such as construction, automobiles, and electronic products and thus can be easily collected with high economic feasibility.
Hereinafter, embodiments and examples of the present disclosure will be described in detail with reference to the accompanying drawings so that the present disclosure may be readily implemented by those skilled in the art. However, it is to be noted that the present disclosure is not limited to the embodiments and examples but can be embodied in various other ways. In drawings, parts irrelevant to the description are omitted for the simplicity of explanation, and like reference numerals denote like parts through the whole document.
Through the whole document, the term “connected to” or “coupled to” that is used to designate a connection or coupling of one element to another element includes both a case that an element is “directly connected or coupled to” another element and a case that an element is “electronically connected or coupled to” another element via still another element.
Through the whole document, the term “on” that is used to designate a position of one element with respect to another element includes both a case that the one element is adjacent to the other element and a case that any other element exists between these two elements.
Further, through the whole document, the term “comprises or includes” and/or “comprising or including” used in the document means that one or more other components, steps, operation and/or existence or addition of elements are not excluded in addition to the described components, steps, operation and/or elements unless context dictates otherwise.
Through the whole document, the term “about or approximately” or “substantially” is intended to have meanings close to numerical values or ranges specified with an allowable error and intended to prevent accurate or absolute numerical values disclosed for understanding of the present disclosure from being illegally or unfairly used by any unconscionable third party.
Through the whole document, the term “step of” does not mean “step for”.
Through the whole document, the term “combination(s) of” included in Markush type description means mixture or combination of one or more components, steps, operations and/or elements selected from a group consisting of components, steps, operation and/or elements described in Markush type and thereby means that the disclosure includes one or more components, steps, operations and/or elements selected from the Markush group.
Through the whole document, a phrase in the form “A and/or B” means “A or B, or A and B”.
In the following description, exemplary embodiments of the present disclosure will be described in detail, but the present disclosure may not be limited thereto.
A first aspect of the present disclosure provides a method of generating hydrogen using plastic containing oxygen, and the method includes subjecting the plastic containing oxygen to a thermal treatment reaction with hydroxide and water vapor to obtain hydrogen, and an amount of generated CO2 is about 10 mol % or less of the total generated gas.
In the method according to an embodiment of the present disclosure, the amount of generated CO2 may be about 10 mol % or less, about 9 mol % or less, about 8 mol % or less, about 7 mol % or less, about 6 mol % or less, about 5 mol % or less, about 4 mol % or less, or about 3 mol % or less of the total generated gas.
In an embodiment of the present disclosure, the method may include: supplying the plastic and the hydroxide to a reactor (a); and obtaining hydrogen and a carbonate product through a thermal treatment reaction while introducing the water vapor into the reactor (b), but may not be limited thereto. In an embodiment of the present disclosure, the process (a) may further include a process of supplying water to the reactor.
In an embodiment of the present disclosure, the carbonate product may be carbonate or bicarbonate. In an embodiment of the present disclosure, the carbonate product may include at least one selected from Na2CO3, K2CO3, Li2CO3, CaCO3, MgCO3, and (NH4)2CO3, but may not be limited thereto.
In an embodiment of the present disclosure, the plastic may include at least one selected from acrylic resin, polyethylene terephthalate (PET), and epoxy resin, but may not be limited thereto. In an embodiment of the present disclosure, the acrylic resin may include a polymer formed by polymerizing one or more monomers selected from alkyl methacrylate and alkyl acrylate, but may not be limited thereto. Specifically, the monomers may include at least one selected from methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and isobutyl methacrylate, but may not be limited thereto. In an embodiment of the present disclosure, the acrylic resin may be poly(methyl methacrylate) (PMMA). In an embodiment of the present disclosure, the plastic may include at least one selected from PMMA and PET.
In an embodiment of the present disclosure, the hydroxide may include at least one selected from KOH, NaOH, LiOH, Ca(OH)2, Mg(OH)2, and NH4OH, but may not be limited thereto.
In an embodiment of the present disclosure, the thermal treatment reaction may be performed at a temperature of about 100° C. to about 600° C., but may not be limited thereto. In an embodiment of the present disclosure, the thermal treatment reaction may be performed at a temperature of about 100° C. to about 600° C., about 150° C. to about 600° C., about 200° C. to about 600° C., about 250° C. to about 600° C., about 300° C. to about 600° C., about 100° C. to about 550° C., about 150° C. to about 550° C., about 200° C. to about 550° C., about 250° C. to about 550° C., about 300° C. to about 550° C., about 100° C. to about 500° C., about 150° C. to about 500° C., about 200° C. to about 500° C., about 250° C. to about 500° C., or about 300° C. to about 500° C., but may not be limited thereto. In an embodiment of the present disclosure, the thermal treatment reaction may be performed at a temperature of about 300° C. to about 500° C., but may not be limited thereto. In an embodiment of the present disclosure, a hydrogen generation efficiency may be high in the temperature range for the thermal treatment reaction, and the optimal temperature range may vary depending on the type of the plastic and the type of the hydroxide.
In an embodiment of the present disclosure, the thermal treatment reaction may be performed at atmospheric pressure, but may not be limited thereto.
In an embodiment of the present disclosure, a mass ratio of the plastic and the hydroxide may be about 1:2 to about 1:5, but may not be limited thereto. In an embodiment of the present disclosure, a mass ratio of the plastic and the hydroxide may be about 1:2 to about 1:5, about 1:3 to about 1:5, about 1:3.5 to about 1:5, about 1:2 to about 1:4.5, about 1:3 to about 1:4.5, or about 1:3.5 to about 1:4.5, but may not be limited thereto. In an embodiment of the present disclosure, a mass ratio of the plastic and the hydroxide may be about 1:4.
In an embodiment of the present disclosure, a purity of the hydrogen obtained by the above-described method may be about 70% or more. In an embodiment of the present disclosure, a purity of the hydrogen obtained by the above-described method may be about 70% or more, about 73% or more, about 75% or more, about 80% or more, about 85% or more, or about 89% or more. The purity of the hydrogen may indicate a ratio (unit: mol) of the hydrogen to the total product obtained by the above-described method of generating hydrogen.
In an embodiment of the present disclosure, an amount of the generated hydrogen obtained by the above-described method may be about 5 mmol or more per 1 g of plastic. In an embodiment of the present disclosure, the amount of the generated hydrogen obtained by the above-described method may be about 5 mmol or more, about 8 mmol or more, about 10 mmol or more, about 15 mmol or more, about 20 mmol or more, about 22 mmol or more, about 24 mmol or more, about 26 mmol or more, or about 28 mmol or more per 1 g of plastic.
In an embodiment of the present disclosure, an amount of generated carbon dioxide obtained by the above-described method may be less than about 1.2 mmol per 1 g of plastic. In an embodiment of the present disclosure, the amount of generated carbon dioxide obtained by the above-described method may be less than about 1.2 mmol, about 1 mmol, or about 0.7 mmol per 1 g of plastic.
A second aspect of the present disclosure provides a method of generating hydrogen using plastic not containing oxygen, and the method includes: thermally oxidizing the plastic not containing oxygen to obtain thermally oxidized plastic; and subjecting the thermally oxidized plastic to a thermal treatment reaction with hydroxide and water vapor to obtain hydrogen.
In an embodiment of the present disclosure, the plastic may be polyethylene, and the thermal oxidation may be performed at a temperature of about 150° C. to about 350° C. In an embodiment of the present disclosure, the plastic may be polyethylene, and the thermal oxidation may be performed at a temperature of about 150° C. to about 350° C., about 150° C. to about 325° C., about 150° C. to about 300° C., about 175° C. to about 350° C., about 175° C. to about 325° C., about 175° C. to about 300° C., about 200° C. to about 350° C., about 200° C. to about 325° C., about 200° C. to about 300° C., about 225° C. to about 350° C., about 225° C. to about 325° C., about 225° C. to about 300° C., about 250° C. to about 350° C., about 250° C. to about 325° C., or about 250° C. to about 300° C.
In an embodiment of the present disclosure, when the plastic is polyethylene, the thermal oxidation may be performed for about 50 hours or more, about 50 hours to about 300 hours, about 50 hours to about 200 hours, about 50 hours to about 100 hours, about 50 hours to about 90 hours, about 50 hours to about 80 hours, about 50 hours to about 70 hours, or about 50 hours to about 60 hours.
In an embodiment of the present disclosure, the plastic may be polypropylene, and the thermal oxidation may be performed at a temperature of about 150° C. to about 300° C. In an embodiment of the present disclosure, the plastic may be polypropylene, and the thermal oxidation may be performed at a temperature of about 150° C. to about 300° C., about 150° C. to about 250° C., about 150° C. to about 225° C., about 150° C. to about 200° C., about 175° C. to about 300° C., about 175° C. to about 250° C., about 175° C. to about 225° C., about 175° C. to about 200° C., about 180° C. to about 300° C., about 180° C. to about 250° C., about 180° C. to about 225° C., about 180° C. to about 200° C., about 190° C. to about 300° C., about 190° C. to about 250° C., about 190° C. to about 225° C., or about 190° C. to about 200° C.
In an embodiment of the present disclosure, when the plastic is polypropylene, the thermal oxidation may be performed for about 50 hours or more, about 50 hours to about 300 hours, about 50 hours to about 200 hours, about 50 hours to about 100 hours, about 50 hours to about 90 hours, about 50 hours to about 80 hours, about 50 hours to about 70 hours, or about 50 hours to about 60 hours.
In an embodiment of the present disclosure, the thermal treatment may include: supplying the plastic and the hydroxide to a reactor (a); and obtaining hydrogen and a carbonate product through a thermal treatment reaction while introducing the water vapor into the reactor (b). In an embodiment of the present disclosure, the process (a) may further include a process of supplying water to the reactor.
In an embodiment of the present disclosure, the carbonate product may be carbonate or bicarbonate. In an embodiment of the present disclosure, the carbonate product may include at least one selected from Na2CO3, K2CO3, Li2CO3, CaCO3, MgCO3, and (NH4)2CO3, but may not be limited thereto.
In an embodiment of the present disclosure, the hydroxide may include at least one selected from KOH, NaOH, LiOH, Ca(OH)2, Mg(OH)2, and NH4OH, but may not be limited thereto.
In an embodiment of the present disclosure, the thermal treatment reaction may be performed at a temperature of about 100° C. to about 700° C. In an embodiment of the present disclosure, the thermal treatment reaction may be performed at a temperature of about 100° C. to about 700° C., about 100° C. to about 650° C., about 100° C. to about 600° C., about 100° C. to about 550° C., about 200° C. to about 700° C., about 200° C. to about 650° C., about 200° C. to about 600° C., about 200° C. to about 550° C., about 250° C. to about 700° C., about 250° C. to about 650° C., about 250° C. to about 600° C., about 250° C. to about 550° C., about 300° C. to about 700° C., about 300° C. to about 650° C., about 300° C. to about 600° C., about 300° C. to about 550° C., about 350° C. to about 700° C., about 350° C. to about 650° C., about 350° C. to about 600° C., about 350° C. to about 550° C., about 400° C. to about 700° C., about 400° C. to about 650° C., about 400° C. to about 600° C., about 400° C. to about 550° C., about 450° C. to about 700° C., about 450° C. to about 650° C., about 450° C. to about 600° C., or about 450° C. to about 550° C., but may not be limited thereto. In an embodiment of the present disclosure, a hydrogen generation efficiency may be high in the temperature range for the thermal treatment reaction, and the optimal temperature range may vary depending on the type of the plastic and the type of the hydroxide. For example, the thermal treatment reaction may be efficiently performed in a narrow temperature range by performing the thermal oxidation in an appropriate temperature range.
In an embodiment of the present disclosure, the thermal treatment reaction may be performed at atmospheric pressure, but may not be limited thereto.
In an embodiment of the present disclosure, a mass ratio of the plastic and the hydroxide may be about 1:2 to about 1:6, but may not be limited thereto. In an embodiment of the present disclosure, a mass ratio of the plastic and the hydroxide may be about 1:2 to about 1:6, about 1:2 to about 1:5, about 1:3 to about 1:6, about 1:3 to about 1:5, about 1:4 to about 1:6, or about 1:4 to about 1:5, but may not be limited thereto.
In an embodiment of the present disclosure, when the plastic is polyethylene, an amount of the generated hydrogen may be about 25 mmol or more per 1 g of plastic. In an embodiment of the present disclosure, when the plastic is polyethylene, the amount of the generated hydrogen may be about 25 mmol or more, about 27 mmol or more, about 30 mmol or more, about 35 mmol or more, or about 40 mmol or more per 1 g of plastic.
In an embodiment of the present disclosure, when the plastic is polypropylene, an amount of the generated hydrogen may be about 10 mmol or more per 1 g of plastic. In an embodiment of the present disclosure, when the plastic is polypropylene, the amount of the generated hydrogen may be about 10 mmol or more, about 12 mmol or more, about 15 mmol or more, or about 17 mmol or more per 1 g of plastic.
Hereinafter, example embodiments are described in more detail by using Examples, but the present disclosure may not limited to the Examples.
At 1 atm pressure, 0.05 g of plastic (PET or PMMA), 0.2 g of NaOH, and 0.2 g of water (H2O) were put into a ceramic boat reactor and then, a reaction was carried out in a temperature range of 100° C. to 600° C. while 7.59 mL of steam was supplied (flow rate: 23 μL/min). Nitrogen was used as a carrier gas (flow rate: 50 mL/min), and the gas generated after the reaction was allowed to pass through a cooler, captured in a gas bag and analyzed in real time by gas chromatography (
The reaction scheme of PMMA or PET, NaOH, and water during the reaction is as follows:
When a reaction was carried out under the same conditions as in Example 1-1, plastic and water were put into a ceramic boat without the addition of a base (NaOH), followed by a steam reforming reaction. Specifically, 0.05 g of plastic (PET or PMMA) and 0.15 g of water were put into a ceramic boat reactor and then, the reaction was carried out in a temperature range of 100° C. to 600° C. while 7.59 mL of steam was supplied (flow rate: 23 μL/min).
When a reaction was carried out under the same conditions as in Example 1-1, polypropylene (PP) and polyethylene (PE) were used as plastics. Specifically, 0.05 g of plastic (PP or PE), 0.3 g of NaOH and 0.3 g of water were put into a ceramic boat reactor and then, the reaction was carried out in a temperature range of 100° C. to 600° C. while 4.14 mL of steam was supplied (flow rate: 23 μL/min).
The reaction scheme of PP or PE, NaOH, and water during the reaction is as follows:
1) In Example 1-1 and Comparative Example 1-1, the gases generated at a reaction temperature of 100° C. to 600° C. were examined by gas chromatography to determine the types and production amounts of the gases (molar amounts of the generated gases per 1 g of plastic) (
2) A hydrogen production rate depending on a reaction temperature (100° C. to 600° C.) in Example 1-1 and Comparative Example 1-1 was examined (
3) A carbon dioxide production rate depending on a reaction temperature (100° C. to 600° C.) in Example 1-1 and Comparative Example 1-1 was examined (
In Example 1-1 and Comparative Example 1-2, the gases generated at a reaction temperature of 100° C. to 600° C. were examined to determine the types and production amounts of the gases (molar amounts of the generated gases per 1 g of plastic) (
In Example 1-1, a gas production amount depending on the particle size of the raw material at a reaction temperature of 100° C. to 600° C. was examined (
After 10 g of a glass fiber reinforced epoxy substrate (MCL-E-67 manufactured by Hitachi Chemical Co., Ltd.) having the composition shown in Table 1 below and covered with copper on both sides, i.e., a sample as a waste electronic component including metal, etc., cut into a square of 5 mm each side and 100 g of potassium carbonate were put into a 1,000 cm3 reactor, the temperature was raised while a nitrogen gas was allowed to flow at 160 cm3/min. Immediately after the temperature of the reactor reached approximately 100° C., steam was introduced at 1.0 g/min and the temperature was raised to a predetermined temperature at intervals of about 20 minutes. The temperature inside the reactor reached 625° C. or 675° C. and was maintained for 60 minutes. Then, the reactor was cooled and the resultant product was taken out. All products flowing out of the reactor during the reaction were cooled to room temperature by passing through a stainless steel pipe dipped in ice water and then separated into water, tar-like substances, and gas products. Thereafter, the gas products were captured in a gas bag. Table 2 below shows the yield of pyrolyzates from the epoxy substrate, and it was confirmed that the pyrolyzates include hydrogen, carbon monoxide, methane, carbon dioxide, tar-like substances, and carbon residues. The carbon residues were heavy organic substances attached to copper or glass fibers recovered by removing potassium carbonate by washing solid products remaining in the reactor after the reaction with water, and the yield of the carbon residues was 1.8%.
When the amount of the product of Example 1-1 was compared with the amount of the product of Comparative Example 1-3 (reaction temperature: 675° C., addition amount of potassium carbonate: 100.2 g), the compositions of hydrogen in the products of Example 1-1 were 73.49% (PMMA) and 94.47% (PET), respectively, and the composition of hydrogen in the product of Comparative Example 1-3 was 6% (yield: 11.1%). In Example 1-1, carbon dioxide was captured as carbonate due to the presence of NaOH during the reaction, and, thus, the compositions of carbon dioxide was as low as 3.05% (PMMA) and 2.13% (PET). However, in Comparative Example 1-3, the composition of carbon dioxide was as high as 84% (yield: 150%).
At 1 atm pressure, 0.1 g of plastic (epoxy resin (C21H24O4)), 0.5 g of NaOH, and 0.5 g of H2O were put into a ceramic boat reactor and then, a reaction was carried out in a temperature range of 100° C. to 950° C. (heating rate: 2° C./min) while steam was supplied at a flow rate of 23 μL/min. Nitrogen was used as a carrier gas (flow rate: 50 mL/min). The structural formula of the epoxy resin (C21H24O4) used above is the same as Chemical Formula 1 below:
The reaction scheme of epoxy resin (C21H24O4), NaOH, and H2O during the reaction is as follows, and a mass ratio of the reactants is C21H24O4:NaOH:H2O=1:4.94:0.9:
Thereafter, the generated gas was analyzed in the same manner as in Example 1-1, and the results are shown in
At 1 atm pressure, 0.1 g of plastic (PET), 0.4 g of Ca(OH)2, and 0.4 g of H2O were put into a ceramic boat reactor and then, a reaction was carried out in a temperature range of 100° C. to 600° C. (heating rate: 2° C./min) while steam was supplied at a flow rate of 23 μL/min. Nitrogen was used as a carrier gas (flow rate: 50 mL/min). The reaction scheme of PET (C10H8O4), Ca(OH)2, and H2O during the reaction is as follows, and a mass ratio of the reactants is C10H8O4:Ca(OH)2:H2O=1:3.86:0.56:
Thereafter, the generated gas was analyzed in the same manner as in Example 1-1, and the results are shown in
Referring to
At 1 atm pressure, a reaction was carried out while a mass ratio of plastics (PET and PMMA) and alkali was adjusted to 1:1, 2, 3, 4, and 5 by fixing the mass of PET and PMMA to 0.1 g and changing the mass of NaOH and H2O to 0.1 g, 0.2 g, 0.3 g, 0.4 g, and 0.5 g, respectively. Also, steam gasification (SG) was carried out without the addition of an alkali under the same conditions. Besides, the reaction was carried out in a temperature range of 100° C. to 700° C. (heating rate: 2° C./min) while steam was supplied at a flow rate of 23 μL/min. Nitrogen was used as a carrier gas (flow rate: 50 mL/min).
Thereafter, the generated gas was analyzed in the same manner as in Example 1-1, and the results are shown in
PE was thermally oxidized at each temperature of 150° C., 175° C., 200° C., 250° C., 300° C., 350° C., and 400° C. for 50 hours. Also, PP was thermally oxidized at each temperature of 150° C., 175° C., 200° C., 300° C., and 400° C. for 50 hours.
PE or PP thermally oxidized as described in paragraph 1), NaOH, and water were added into a ceramic boat reactor and then, alkaline thermal treatment was carried out in a temperature range of 100° C. to 600° C. while 7.59 mL of steam was supplied (flow rate: 23 μL/min). Nitrogen was used as a carrier gas (flow rate: 50 mL/min), and the gas produced after the reaction was allowed to pass through a cooler, captured in a gas bag and analyzed by gas chromatography. In this case, a mass ratio of plastic (PE or PP) and NaOH is 1:5.
In Example 2-1, an additional test was conducted under thermal oxidation conditions set to (150° C., 50 hours), (150° C., 100 hours), (200° C., 50 hours), and (200° C., 100 hours). Referring to
In Example 2-1, an additional test was conducted under thermal oxidation conditions set to (100° C., 90 hours). Referring to
The above description of the example embodiments is provided for the purpose of illustration, and it would be understood by those skilled in the art that various changes and modifications may be made without changing technical conception and essential features of the example embodiments. Thus, it is clear that the above-described example embodiments are illustrative in all aspects and do not limit the present disclosure. For example, each component described to be distributed can be implemented in a combined manner.
The scope of the inventive concept is defined by the following claims and their equivalents rather than by the detailed description of the example embodiments. It shall be understood that all modifications and embodiments conceived from the meaning and scope of the claims and their equivalents are included in the scope of the inventive concept.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0130031 | Sep 2021 | KR | national |
| 10-2023-0066749 | May 2023 | KR | national |
This application is a continuation in-part application of PCT Application No. PCT/KR2022/014735 filed on Sep. 30, 2022, which claims the benefit of Korean Patent Application No. KR 10-2021-0130031 filed on Sep. 30, 2021, and this application also claims the benefit of Korean Patent Application No. KR 10-2023-0066749 filed on May 24, 2023. The entire contents of the aforementioned related applications are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2022/014735 | Sep 2022 | WO |
| Child | 18619268 | US |
