Method and system for producing hydrogen

Abstract

The present disclosure relates to a method and a system for producing hydrogen, the method comprising the steps of: (S1) purifying landfill gas, thereby generating a first mixed gas; (S2) performing steam reforming on the first mixed gas in a first reactor, thereby generating a second mixed gas; (S3) separating the second mixed gas into a first stream comprising carbon dioxide and a second stream comprising hydrogen and carbon monoxide; (S4) introducing the first stream, separated out in step (S3), into a second reactor and converting same into carbon monoxide through reverse Boudouard reaction; (S5) mixing the second stream and the carbon monoxide converted in step (S4), thereby preparing a third mixed gas; (S6) generating syngas from the third mixed gas through water-gas shift reaction; and (S7) separating carbon dioxide from the syngas, thereby obtaining hydrogen.

Description

Hydrogen production method and system

[0001] The present disclosure relates to a method and system for producing hydrogen.

[0002] Landfill gas (LFG) is a gas generated by the anaerobic decomposition of organic matter in landfills. Its main components are methane and carbon dioxide. Recently, methods and technologies for recycling this landfill gas are being developed. A representative example is the gasification process, which uses landfill gas to produce synthesis gas and converts it into high-value-added products for energy production.

[0003] The gasification process generally refers to a series of processes that convert carbonaceous raw materials such as coal, organic waste, and biomass into synthesis gas by reacting them under the supply of steam, oxygen, carbon dioxide, or a mixture thereof.

[0004] Gasification process technology has expanded to produce various compounds as raw materials and fuels. For example, the hydrogen contained in synthesis gas can be used for hydrogen power generation, ammonia production, and oil refining. However, the yield of hydrogen obtained from synthesis gas produced from landfill gas is very low, making it difficult to effectively extract hydrogen from landfill gas.

[0005] Recently, catalytic gasification processes have been implemented to produce synthesis gas. However, the gasification process has been plagued by problems such as catalyst deactivation caused by coke formation, leading to process failures during continuous operation. Furthermore, to ensure economic viability, the relatively expensive catalyst must be recovered. However, recovering the catalyst, which is discharged in a coagulated state with coke and other contaminants, requires multiple subsequent steps (e.g., air burning), significantly reducing process efficiency.

[0006] Furthermore, the conventional landfill gas gasification process yields significantly lower productivity, with a yield of less than 30% for synthesis gas, which can be converted into high-value-added products. This limits its utilization and commercialization. While reducing carbon dioxide emissions is desirable from an environmental perspective, landfill gas gasification products contain carbon dioxide in addition to hydrogen and carbon monoxide, leading to significant carbon dioxide emissions, potentially contributing to further environmental pollution.

[0007] Accordingly, there is a need for a hydrogen production method and production system that can efficiently obtain hydrogen by improving the yield of synthesis gas that can be converted into a high value-added product during the gasification process of landfill gas and hydrogen obtained therefrom, while minimizing the generation of carbon dioxide.

[0008] According to one aspect of the present disclosure, the yield of hydrogen production from landfill gas can be significantly improved.

[0009] In addition, according to another aspect of the present disclosure, a method and system for producing hydrogen with significantly improved process efficiency can be provided.

[0010] In addition, according to another aspect of the present disclosure, a method and system for producing hydrogen that can minimize the generation of carbon dioxide can be provided.

[0011] According to one aspect of the present disclosure, no residual gas may be generated during hydrogen production.

[0012] Additionally, according to another aspect of the present disclosure, the catalyst can be regenerated to perform a continuous dual circulation fluidized bed reaction.

[0013] The present disclosure provides a method for producing hydrogen, comprising: (S1) refining landfill gas to produce a first mixed gas; (S2) steam reforming the first mixed gas in a first reactor to produce a second mixed gas; (S3) separating the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide; (S4) introducing the first stream separated in step (S3) into a second reactor and converting it into carbon monoxide through a reverse Boudouard reaction; (S5) mixing the second stream with the carbon monoxide converted in step (S4) to produce a third mixed gas; (S6) generating a synthesis gas from the third mixed gas through a water gas shift reaction; and (S7) separating carbon dioxide from the synthesis gas to obtain hydrogen.

[0014] In one embodiment according to the present disclosure, the step (S1) may include a step of removing at least one selected from the group consisting of sulfur, chlorine, carbonyl sulfide, tar, nitrogen, benzene, toluene, ethylbenzene, xylene, CHCl3, CCl4, CH3CCl3, C2H2Cl2, H2S and NH3 from the landfill gas.

[0015] In one embodiment according to the present disclosure, the second reactor may be supplied with a carbon source from an external source.

[0016] In one embodiment according to the present disclosure, the first stream may contain carbon dioxide in an amount of 50% by volume or more.

[0017] In one embodiment according to the present disclosure, the first mixed gas may have a C / O element ratio of 0.15 to 15.

[0018] In one embodiment according to the present disclosure, the step (S2) may be performed under a composite catalyst in which an active metal is supported on a support.

[0019] In one embodiment according to the present disclosure, the active metal may include one or more selected from the group consisting of nickel, vanadium, iron, platinum, palladium, and ruthenium.

[0020] In one embodiment according to the present disclosure, the support may include at least one selected from the group consisting of silica, alumina, silica-alumina, carbon, zirconia, titania, zeolite, SAPO, and ALPO.

[0021] In one embodiment according to the present disclosure, the step (S2) may be performed at a temperature of 700 to 1000°C.

[0022] In one embodiment according to the present disclosure, the step (S4) may be performed at a temperature of 600 to 1000°C and a pressure of 50 to 300 KPa.

[0023] In addition, the present disclosure provides a hydrogen production system comprising: a purification unit for purifying landfill gas to produce a first mixed gas; a first reactor for subjecting the first mixed gas to a steam reforming reaction under a catalyst to produce a second mixed gas; a carbon dioxide separation unit for separating the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide; a second reactor for converting the first stream into carbon monoxide through a reverse Boudouard reaction; and a gas mixing unit for mixing the second stream with carbon monoxide converted from the second reactor to produce a third mixed gas; and a synthesis gas production unit for converting the third mixed gas into synthesis gas through a water gas shift reaction; wherein carbon dioxide is separated from the synthesis gas in the carbon dioxide separation unit to obtain hydrogen.

[0024] In one embodiment according to the present disclosure, the first reactor may be a first fluidized bed reactor, and the second reactor may be a second fluidized bed reactor.

[0025] In one embodiment according to the present disclosure, the hydrogen production system further includes a cyclone connected between the first fluidized bed reactor and the carbon dioxide separation unit; a catalyst supply line connecting the cyclone and the second fluidized bed reactor; and a catalyst recirculation line connecting the second fluidized bed reactor and the first fluidized bed reactor, wherein the cyclone may separate a second mixed gas and a catalyst discharged from the first fluidized bed reactor, supply the second mixed gas to the carbon dioxide separation unit, and supply the catalyst to the second fluidized bed reactor.

[0026] In one embodiment according to the present disclosure, the purification unit may include at least one selected from the group consisting of a scrubber, an adsorption tower, and a pressure swing adsorption (PSA).

[0027] A hydrogen production method and system according to one embodiment of the present disclosure can significantly improve the production yield of hydrogen from landfill gas.

[0028] A hydrogen production method and system according to another embodiment of the present disclosure can significantly improve process efficiency.

[0029] A hydrogen production method and system according to another embodiment of the present disclosure can minimize the generation of carbon dioxide.

[0030] A hydrogen production method and system according to one embodiment of the present disclosure may not generate residual gas during hydrogen production.

[0031] A hydrogen production method and system according to another embodiment of the present disclosure can perform a continuous dual circulation fluidized bed reaction by regenerating a catalyst.

[0032] A hydrogen production method and system according to another embodiment of the present disclosure can produce hydrogen from landfill gas in an eco-friendly manner.

[0033] FIG. 1 is a schematic diagram showing a hydrogen production system according to one embodiment of the present disclosure.

[0034] FIG. 2 is a schematic diagram showing a hydrogen production system including a catalyst circulation process according to one embodiment of the present disclosure.

[0035] The advantages and features of the present disclosure, and methods for achieving them, will become clearer with reference to the embodiments described in detail below. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided solely to ensure the complete disclosure of the present disclosure and to fully inform those skilled in the art of the present disclosure of the scope of the invention. The present disclosure is defined solely by the scope of the claims.

[0036] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used in a meaning that can be commonly understood by a person of ordinary skill in the art to which this disclosure belongs.

[0037] As used herein, the singular forms of terms may be construed to include the plural forms as well, unless otherwise specified.

[0038] The numerical ranges used herein include lower and upper limits and all values ​​within that range, increments logically derived from the shape and width of the defined range, all doubly defined values, and all possible combinations of upper and lower limits of numerical ranges defined in different shapes. Unless otherwise specified in the specification of the present disclosure, values ​​outside the defined range that may arise due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0039] The term "includes" as used herein is an open-ended description having the equivalent meaning of expressions such as "comprises," "contains," "has," and "characterizes," and does not exclude additional elements, materials, or processes not listed.

[0040] The unit of % used in this specification without special mention means weight % unless otherwise defined.

[0041] In this specification, “A to B” means “A or more and B or less” unless otherwise specifically defined.

[0042] In this specification, “syngas” means a mixed gas containing hydrogen and carbon dioxide, and may additionally contain carbon monoxide.

[0043] Below, the hydrogen production method and system of the present disclosure will be described in detail. However, these are merely exemplary, and the present disclosure is not limited to the specific embodiments described as examples.

[0044] Conventionally, a gasification process using a catalyst has been implemented as a process for producing synthesis gas. However, there has been a problem that the catalyst is deactivated due to the generation of coke, etc. during the gasification process, and process troubles occur due to the deactivated catalyst during continuous operation. In addition, to ensure economic feasibility, the relatively expensive catalyst needs to be recovered. However, in order to recover the catalyst discharged in a coagulated state such as coke, multiple subsequent processes (such as air burning) must be performed, which significantly reduces the process efficiency and causes environmental pollution due to the emission of a large amount of carbon dioxide during the process. In addition, the conventional landfill gas gasification process has a significantly low synthesis gas production yield of less than 30% and a low hydrogen production yield, which reduces productivity. Therefore, the inventors of the present disclosure have devised a production method and system that can achieve a significantly high hydrogen yield from landfill gas while minimizing the amount of carbon dioxide generated.

[0045] The present disclosure provides a method for producing hydrogen, comprising: (S1) refining landfill gas to produce a first mixed gas; (S2) steam reforming the first mixed gas in a first reactor to produce a second mixed gas; (S3) separating the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide; (S4) introducing the first stream separated in step (S3) into a second reactor and converting it into carbon monoxide through a reverse Boudouard reaction; (S5) mixing the second stream with the carbon monoxide converted in step (S4) to produce a third mixed gas; (S6) generating a synthesis gas from the third mixed gas through a water gas shift reaction; and (S7) separating carbon dioxide from the synthesis gas to obtain hydrogen.

[0046] The hydrogen production method according to the present disclosure can efficiently convert landfill gas into synthesis gas compared to conventional gasification processes, thereby maximizing the yield of high-value-added hydrogen produced from the synthesis gas. Furthermore, the carbon dioxide generated during the synthesis gas production process can be converted into a raw material for the synthesis gas, thereby minimizing carbon dioxide emissions during the hydrogen production process and preventing environmental pollution.

[0047] In one embodiment according to the present disclosure, the first mixed gas may include methane, hydrogen, carbon monoxide and carbon dioxide.

[0048] As an example of increasing the methane content in the first mixed gas, the first mixed gas may further include one or more selected from the group consisting of landfill gas, shale gas, refinery exhaust gas, and biogas. Since the above-described landfill gas, shale gas, refinery exhaust gas, and biogas contain methane and carbon dioxide in an amount of 40% by volume or more, specifically, 50% by volume or more, since the first mixed gas further includes the above-described gases, there is an effect of further improving the production yield of synthesis gas through subsequent processes such as steam reforming and reverse Budar reaction.

[0049] In one embodiment according to the present disclosure, the C / O element ratio of the first mixed gas may be, as an upper limit, 15 or less and 4 or less, and as a lower limit, 0.15 or more and 0.3 or more, specifically, 0.15 to 15, and more specifically, 0.3 to 4.

[0050] The method for producing hydrocarbons according to the present disclosure enables a steam reforming reaction to be smoothly performed even when the first mixed gas contains a relatively high C / O element ratio within the above-described range. Specifically, since the catalyst used in the steam reforming reaction forms a cyclic process as described below, the reaction can be continuously performed regardless of catalyst deactivation due to coke that may be generated by the steam reforming reaction.

[0051] The above landfill gas may contain at least one impurity selected from the group consisting of sulfur, chlorine, carbonyl sulfide, tar, and nitrogen. Specifically, the landfill gas may contain impurities such as benzene, toluene, ethylbenzene, xylene, CHCl3, CCl4, CH3CCl3, C2H2Cl2, H2S, and tar. These impurities contained in the landfill gas may induce catalyst deactivation, thereby reducing the efficiency of the subsequent process. Therefore, purifying the landfill gas by removing impurities can improve the efficiency of the overall process.

[0052] In one embodiment according to the present disclosure, the step (S1) may include removing at least one selected from the group consisting of sulfur, chlorine, carbonyl sulfide, tar, nitrogen, benzene, toluene, ethylbenzene, xylene, CHCl3, CCl4, CH3CCl3, C2H2Cl2, H2S and NH3 from the landfill gas.

[0053] The above step (S1) may be performed in at least one selected from the group consisting of a scrubber, an adsorption tower, and a pressure swing adsorption (PSA).

[0054] In addition, the purification may be at least one or a combination of two or more selected from the group consisting of using a high-pressure dust filter, water washing, alkaline solution washing, and passing through a ceramic filter, but is not limited thereto. When water washing or alkaline solution washing is used, impurities such as H2S and NH3 contained in the landfill gas can be removed, and when the landfill gas is passed through a ceramic filter or dust filter, impurities such as tar and dust can be removed.

[0055] In one embodiment according to the present disclosure, step (S2) is a step of producing a second mixed gas by steam reforming methane contained in the first mixed gas in a first reactor. In step (S2), a reforming reaction according to the following reaction scheme 1 may be performed.

[0056] [Reaction Formula 1]

[0057] CH4+ H2O → CO + 3H2 (steam reforming reaction)

[0058] The reforming reaction of the above step (S2) can be performed at a temperature of 600 to 1400°C and a pressure of 30 to 2000 KPa.

[0059] The above step (S2) may be operated without a catalyst, but may be operated using a catalyst to increase the reaction conversion rate at a low temperature of about 600 to 700°C. The catalyst of the above step (S2) may be a composite catalyst in which an active metal is supported on a support. The active metal may include at least one selected from the group consisting of nickel, vanadium, iron, platinum, palladium, and ruthenium. Typically, the active metal may be nickel, vanadium, or iron, and in cases where the raw material, such as organic waste, has a low impurity content during the heat treatment process, a noble metal such as platinum, palladium, or ruthenium may be used.

[0060] In one embodiment according to the present disclosure, the support may be a solid acid material such as an oxide or a zeolite, and specifically, may be at least one selected from the group consisting of ZSM-5, ZSM-11, USY zeolite, Ferrierite, Mordenite, MCM-22, SUZ-4, L-type zeolite, silica, alumina, silica-alumina, carbon, zirconia, and titania.

[0061] The above steam reforming reaction may be performed in a first fixed bed reactor or a first fluidized bed reactor.

[0062] By performing the steam reforming reaction of the above step (S2) in the first fixed bed reactor, the reforming reactivity and process stability of methane can be improved, thereby producing synthesis gas at a high yield, thereby improving the hydrogen yield. Specifically, when methane is reformed using the steam reforming reaction, not only is the reforming reactivity improved compared to dry reforming, but impurities such as chlorine are also removed, and carbon accumulation on the reforming catalyst is almost non-existent, enabling a continuous process.

[0063] In addition, since step (S2) is performed in the first fluidized bed reactor, the catalyst can be regenerated and then supplied to the subsequent reverse-Buda reaction process, forming a circulation process. Since the steam reforming reaction is performed in step (S2), coke may accumulate on the catalyst, which may deactivate the catalytic reaction. However, since step (S2) is performed in the first fluidized bed reactor, a circulation process of regenerating and resupplying the catalyst can be performed, continuous reforming reaction is possible even during steam reforming.

[0064] (S3) Step is a step of separating the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide.

[0065] In one embodiment according to the present disclosure, the method for separating the second mixed gas into a first stream and a second stream is not limited to any known method, but the present disclosure allows separation using a carbon dioxide separation unit, and the carbon dioxide separation unit may be an amine scrubber. Typically, an amine scrubber separates components such as carbon dioxide and hydrogen sulfide from a gas vapor by combining and removing carbon dioxide through an amine-based material, and can recover a gas containing hydrogen, carbon monoxide, or an inert gas. Therefore, by using an amine scrubber, the first mixed gas can be separated into a first stream and a second stream.

[0066] In another embodiment according to the present disclosure, the carbon dioxide separation unit may be a CCS unit (Carbon capture and storage unit). When the CCS unit is used to separate carbon dioxide, the CCS unit may adsorb and separate carbon dioxide using an adsorbent comprising one or more selected from calcium oxide, calcium hydroxide, dolomite, limestone, and trona. The second mixed gas may be separated into a first stream and a second stream using the CCS unit (Carbon capture and storage unit).

[0067] The first stream may contain carbon dioxide in an amount of 40% by volume or more, 50% by volume or more, or 60% by volume or more, and 99% by volume or less, 90% by volume or less, 80% by volume or less, or 70% by volume or less. Specifically, the first stream may contain carbon dioxide in an amount of 40 to 99% by volume, and more specifically, 50 to 80% by volume. In a carbon dioxide separation unit, when capturing carbon dioxide and separating it, in order to separate carbon dioxide with high purity, the regeneration tower where the carbon dioxide is separated from the adsorbent must be designed with a high stage, which consumes more energy. Therefore, since the first stream contains carbon dioxide in the above-described range, the carbon dioxide separation process can be performed under slightly milder conditions.

[0068] In one embodiment according to the present disclosure, step (S4) is a step of introducing the first stream separated in step (S3) into a second reactor and converting it into carbon monoxide through a reverse Boudouard reaction. By additionally converting the carbon dioxide contained in the first stream into carbon monoxide through the reverse Boudouard reaction, environmental pollution can be prevented in terms of reducing carbon dioxide emissions, while also maximizing the yield of synthesis gas and thus the yield of hydrogen. The reverse Boudouard reaction may involve the following reaction scheme 2.

[0069] [Reaction Formula 2]

[0070] C + CO2→ 2CO

[0071] The above step (S4) can be performed at a temperature of 600 to 1000°C and a pressure of 50 to 300 KPa.

[0072] In one embodiment according to the present disclosure, the carbon source for the reverse reaction in step (S4) may be the catalyst deposited with coke supplied in step (S2). Additionally, the reaction may be performed by externally supplying activated carbon, graphite, or the like, as needed. The graphite may be high-purity graphite.

[0073] The above reverse reaction may be performed in a second fixed bed reactor or a second fluidized bed reactor.

[0074] Since the reverse Buta reaction of the above step (S4) is performed in the second fixed bed reactor, carbon dioxide can be converted into carbon monoxide with high efficiency even if the first stream contains carbon dioxide in the above-described range. In addition, when the present disclosure uses the first fixed bed reforming reactor in step (S2), it may be advantageous in terms of improving the reactivity of the reverse Buta reaction by using the second fixed bed reverse Buta reactor with excellent reaction efficiency in step (S4), in terms of improving the production amount of synthesis gas.

[0075] When the steam reforming reaction of the above step (S2) is performed in the first fluidized bed reactor, the second mixed gas discharged from the first fluidized bed reactor may be supplied to the second fluidized bed reactor where the reverse Buta reaction is performed through a catalyst supply line after the catalyst is separated by a cyclone. In the second fluidized bed reactor (40), the catalyst is reacted as a carbon source for the reverse Buta reaction and regenerated, and the regenerated catalyst may be supplied back to the first fluidized bed reactor (20) through a recirculation line. By using this catalyst circulation process, the reforming reaction can be performed continuously, and since there is no need to supply a carbon source required for the reverse Buta reaction from the outside, the process can be performed economically.

[0076] That is, according to one embodiment of the present disclosure, while the yield of synthesis gas can be maximized through the steam reforming reaction and the reverse Buta reaction, continuous and economical process operation can be simultaneously implemented through catalyst regeneration as the first fluidized bed reactor and the second fluidized bed reactor in which the steam reforming reaction and the reverse Buta reaction are performed form a circulation process.

[0077] In one embodiment according to the present disclosure, the step (S5) may be a step of generating a third mixed gas by mixing the second stream separated from the carbon dioxide separation unit and the carbon monoxide converted by the reverse reaction in the step (S4).

[0078] The third mixed gas may include hydrogen and carbon monoxide.

[0079] In one embodiment according to the present disclosure, step (S6) is a process for generating synthesis gas through a water-gas shift reaction. The third mixed gas can be converted into synthesis gas through a water-gas shift reaction. The water-gas shift reaction may involve the following chemical formula 3.

[0080] [Chemical Formula 3]

[0081] CO + H2O → H2 + CO2

[0082] The above synthesis gas refers to a mixed gas containing hydrogen and carbon dioxide, and may additionally contain carbon monoxide.

[0083] The above water gas shift reaction can be performed under a catalyst containing Fe and Cr.

[0084] The above water-gas shift reaction can be performed at a temperature of 100 to 400°C, specifically 100 to 300°C, and a pressure of 20 to 80 bar, specifically 25 to 70 bar.

[0085] The above water gas shift reaction can be performed repeatedly so that the conversion rate of carbon dioxide is 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more.

[0086] In one embodiment according to the present disclosure, the step (S7) is a step of obtaining hydrogen by separating carbon dioxide from the synthesis gas.

[0087] The above step (S7) can utilize the carbon dioxide separation unit of the above step (S3). That is, in the above step (S7), the synthesis gas can be reintroduced into the carbon dioxide separation unit of the above step (S3) to separate carbon dioxide.

[0088] Additionally, the present disclosure provides a hydrogen production system. The description of the hydrogen production method can be equally applied to the hydrogen production system, within the scope of overlap.

[0089] The present disclosure provides a hydrogen production system comprising: a purification unit for purifying landfill gas to produce a first mixed gas; a first reactor for subjecting the first mixed gas to a steam reforming reaction under a catalyst to produce a second mixed gas; a carbon dioxide separation unit for separating the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide; a second reactor for converting the first stream into carbon monoxide through a reverse Boudouard reaction; and a gas mixing unit for mixing the second stream with carbon monoxide converted from the second reactor to produce a third mixed gas; and a synthesis gas production unit for converting the third mixed gas into synthesis gas through a water gas shift reaction; wherein carbon dioxide is separated from the synthesis gas in the carbon dioxide separation unit to obtain hydrogen.

[0090] The hydrogen production system (1) according to the present disclosure can efficiently and economically produce synthesis gas (230) and hydrogen by performing a steam reforming reaction and a reverse Budar reaction, and can significantly reduce carbon dioxide emissions.

[0091] In one embodiment according to the present disclosure, the purification unit (10) can remove at least one selected from the group consisting of sulfur, chlorine, carbonyl sulfide, tar, nitrogen, benzene, toluene, ethylbenzene, xylene, CHCl3, CCl4, CH3CCl3, C2H2Cl2, H2S and NH3 from the landfill gas.

[0092] Additionally, the purification unit (10) may include at least one selected from the group consisting of a scrubber, an adsorption tower, and a PSA (Pressure Swing Adsorption).

[0093] The above purification unit (10) includes a sprinter that sprays liquid to contact landfill gas (100) with a weakly basic solution containing water or sodium carbonate to remove impurities such as H2S, HCl, HOCl, and NH3, or can remove dust using a high-pressure dust collecting filter, and can remove impurities such as tar by including a ceramic filter, etc.

[0094] Referring to FIG. 1, landfill gas (100) is introduced into a purification unit (10) to produce a first mixed gas (110). The first mixed gas (110) is introduced into a first reactor (20) and converted into a second mixed gas (200) through a steam reforming reaction.

[0095] The above second mixed gas is introduced into a carbon dioxide separation unit (30) and separated into a first stream (210) containing carbon dioxide and a second stream (211) containing hydrogen and carbon monoxide. The second stream is directly supplied to a gas mixing unit (50), and the first stream is supplied to a second reactor (40) and converted into carbon monoxide through a reverse Buta reaction.

[0096] In one embodiment according to the present disclosure, the first reactor may be a first fluidized bed reactor, and the second reactor may be a second fluidized bed reactor.

[0097] In addition, referring to FIG. 2, in one embodiment according to the present disclosure, the hydrogen production system (1) further includes a cyclone (70) connected between the first fluidized bed reactor and the carbon dioxide separation unit; a catalyst supply line connecting the cyclone and the second fluidized bed reactor; and a catalyst recirculation line connecting the second fluidized bed reactor and the first fluidized bed reactor, wherein the cyclone (70) separates a second mixed gas and a catalyst discharged from the first fluidized bed reactor, supplies the second mixed gas to the carbon dioxide separation unit (30), and supplies the catalyst to the second fluidized bed reactor.

[0098] The hydrogen production system of the present disclosure enables continuous process operation through catalyst regeneration, as the first and second fluidized bed reactors described above form a cyclic process. Furthermore, the coke-deposited catalyst supplied from the first fluidized bed reactor can be utilized without the need for a separate carbon source for performing the reverse Buta reaction in the second fluidized bed reactor, enabling more economical process operation.

[0099] The above gas mixing unit (50) mixes the second stream (211) with carbon monoxide converted in the second fluidized bed reactor (40) to produce a third mixed gas (220). The third mixed gas (220) is supplied to the water gas conversion unit (60) and converted into synthesis gas (230) through a water gas conversion reaction.

[0100] The above synthesis gas can be reintroduced into the carbon dioxide separation unit (30) to separate carbon dioxide. From this, hydrogen can be obtained.

[0101] Hereinafter, embodiments of the present disclosure will be further described with reference to specific experimental examples. The examples and comparative examples included in the experimental examples are merely illustrative of the present disclosure and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications to the examples are possible within the scope and technical idea of ​​the present disclosure, and it is also natural that such changes and modifications fall within the scope of the appended claims.

[0102] [Example 1]

[0103] 2.0 L / g of landfill gas having the composition shown in Table 1 below. cat ·h was injected into a scrubber to remove sulfur and chlorine, injected into an adsorption tower to remove carbonyl sulfide and tar, and then injected into a PSA (Pressure Swing Adsorption) to remove nitrogen, thereby recovering the first mixed gas.

[0104] Composition of the substanceMajor components (vol%)CH460.7CO225.3N28.7O23.1Impurities (ppm)Benzene5.3Toluene35.1Ethylbenzene15.3Xylene15.4CHCl3199.3CCl484.3CH3CCl32.3C2H2Cl22.2H2S221.3Others (wt%)Moisture0.13

[0105] The above first mixed gas is supplied to the first fluidized bed reactor and simultaneously steam is supplied to the Ni / Al2O3 catalyst at 900 ℃, 2.0 L / g cat ·h, and a second mixed gas was produced through steam reforming under the operating conditions of CH4 / H2O = 3.

[0106] The second mixed gas is introduced into an amine scrubber, and the carbon dioxide in the second mixed gas is captured in the amine scrubber and separated into a second stream from which the carbon dioxide is separated. Specifically, the second mixed gas is introduced into a first amine scrubber, and the carbon dioxide is captured in a 12 wt% amine aqueous solution containing MEA (Monoethanolamine) dissolved therein at 50°C, and the uncaptured gas is recovered as a second stream. The amine aqueous solution of the first amine scrubber is introduced into a second amine scrubber, and is separated into the amine aqueous solution and carbon dioxide at 100°C, and the carbon dioxide is recovered as a first stream.

[0107] The recovered first stream was fed into the second fluidized bed reactor and converted into carbon monoxide through the reverse Buta reaction. The reverse Buta reaction was performed by supplying the first stream to the second fluidized bed reactor and simultaneously continuously supplying high purity graphite, and the Ni / Al2O3 spent catalyst used in the first fluidized bed reactor was heated to 750°C and the throughput was 2.0 L / g. cat · It was performed under h operating conditions. 71% of carbon dioxide was converted to carbon monoxide through the reverse reaction. The spent Ni / Al2O3 catalyst was regenerated and supplied to the first fluidized bed reactor.

[0108] Carbon monoxide converted from the first stream and the second stream were introduced into a gas mixing unit and mixed at 200°C to produce a third mixed gas.

[0109] The third mixed gas is fed into the synthesis gas generation unit and is treated under the Cu / Zn / Al2O3 catalyst at 165 ℃, 35 bar, throughput 1.4 L / g cat · Synthesis gas with a molar ratio of H2:CO2 = 1.6:1 was produced through a water-gas shift reaction performed under operating conditions of h.

[0110] The above-mentioned synthesis gas was then fed back into the amine scrubber. The carbon dioxide in the synthesis gas was captured in the amine scrubber, and hydrogen was produced. The hydrogen produced compared to the landfill gas fed as feed is shown in Table 2 below.

[0111] [Comparative Example 1]

[0112] The same procedure as Example 1 was followed, except that the subsequent process was not performed after obtaining the second stream in Example 1. The hydrogen content in the obtained second stream compared to the landfill gas fed as feed is shown in Table 2 below.

[0113] [Comparative Example 2]

[0114] The same procedure as in Example 1 was followed, except that the reverse reaction was not performed. The hydrogen obtained compared to the landfill gas fed as feed is shown in Table 2 below.

[0115] Hydrogen obtained (vol%) compared to landfill gas fed as feed Example 1372.5 Comparative Example 1190.2 Comparative Example 2267.9

[0116] When the second stream was obtained as in Comparative Example 1 above and the subsequent process was not performed, the hydrogen obtained compared to the landfill gas fed as feed was confirmed to be 190.2 vol%.

[0117] When the reverse reaction was not performed as in Comparative Example 2 above, the hydrogen obtained compared to the landfill gas fed as feed was confirmed to be 267.9 vol%.

[0118] However, when the reverse Buta reaction was performed as in Example 1 and then the water-to-gas shift reaction was performed, the hydrogen obtained was confirmed to be 372.5 vol% compared to the landfill gas fed as feed. That is, it can be confirmed that when the reverse Buta reaction was performed as in Example 1 and then the water-to-gas shift reaction was performed, a significantly larger amount of hydrogen can be obtained compared to Comparative Examples 1 and 2.

[0119] 1 Hydrogen production system

[0120] 10 refined units

[0121] 20 Reactor 1

[0122] 30 carbon dioxide separation units

[0123] 40 Second Reactor

[0124] 50 gas mixing units

[0125] 60 synthesis gas generation units

[0126] 70 cyclones

[0127] 100 landfill gas

[0128] 110 First mixed gas

[0129] 200 Second mixed gas

[0130] 210 First Stream

[0131] 211 Second Stream

[0132] 220 Third mixed gas

[0133] 230 Syngas

Claims

1. (S1) A step of purifying landfill gas to produce a first mixed gas; (S2) A step of generating a second mixed gas by steam reforming the first mixed gas in a first reactor; (S3) a step of separating the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide; (S4) A step of introducing the first stream separated in the step (S3) into a second reactor and converting it into carbon monoxide through a reverse Boudouard reaction; (S5) a step of producing a third mixed gas by mixing the second stream and the carbon monoxide converted in step (S4); (S6) a step of generating synthesis gas through a water gas conversion reaction from the third mixed gas; and (S7) A method for producing hydrogen, comprising: a step of separating carbon dioxide from the synthesis gas to obtain hydrogen.

2. In paragraph 1, The above (S1) step is to remove sulfur, chlorine, carbonyl sulfide, tar, nitrogen, benzene, toluene, ethylbenzene, xylene, CHCl from the landfill gas. 3 , CCl 4 , CH 3 CCl 3 , C 2 H 2 Cl 2 , H 2 S and NH 3 A method for producing hydrogen, comprising the step of removing at least one selected from the group consisting of:

3. In paragraph 1, A method for producing hydrogen, wherein the second reactor receives a carbon source from an external source.

4. In paragraph 1, A method for producing hydrogen, wherein the first stream contains carbon dioxide at 50% by volume or more.

5. In paragraph 1, A method for producing hydrogen, wherein the first mixed gas has a C / O element ratio of 0.15 to 15.

6. In paragraph 1, A method for producing hydrogen, wherein the step (S2) is performed under a composite catalyst in which an active metal is supported on a support.

7. In paragraph 6, A method for producing hydrogen, wherein the active metal comprises at least one selected from the group consisting of nickel, vanadium, iron, platinum, palladium, and ruthenium.

8. In paragraph 7, A method for producing hydrogen, wherein the support comprises at least one selected from the group consisting of silica, alumina, silica-alumina, carbon, zirconia, titania, zeolite, SAPO and ALPO.

9. In paragraph 1, A method for producing hydrogen, wherein the step (S2) is performed at a temperature of 700 to 1000°C.

10. In paragraph 1, A method for producing hydrogen, wherein the step (S4) is performed at a temperature of 600 to 1000 ℃ and a pressure of 50 to 300 KPa.

11. A purification unit that purifies landfill gas to produce a first mixed gas; A first reactor for generating a second mixed gas by subjecting the first mixed gas to a steam reforming reaction under a catalyst; A carbon dioxide separation unit that separates the second mixed gas into a first stream containing carbon dioxide and a second stream containing hydrogen and carbon monoxide; A second reactor that converts the first stream into carbon monoxide through a reverse Boudouard reaction; A gas mixing unit that produces a third mixed gas by mixing the second stream and carbon monoxide converted from the second reactor; and A synthesis gas generating unit that converts the third mixed gas into synthesis gas through a water gas shift reaction; Including, A hydrogen production system that obtains hydrogen by separating carbon dioxide from the synthesis gas in the carbon dioxide separation unit.

12. In paragraph 11, A hydrogen production system, wherein the first reactor is a first fluidized bed reactor, and the second reactor is a second fluidized bed reactor.

13. In paragraph 12, The above hydrogen production system, A cyclone connected between the first fluidized bed reactor and the carbon dioxide separation unit; A catalyst supply line connecting the above cyclone and the second fluidized bed reactor; and It further includes a catalyst recirculation line connecting the second fluidized bed reactor and the first fluidized bed reactor, A hydrogen production system in which the above cyclone separates the second mixed gas and catalyst discharged from the first fluidized bed reactor, supplies the second mixed gas to a carbon dioxide separation unit, and supplies the catalyst to the second fluidized bed reactor.

14. In paragraph 11, A hydrogen production system, wherein the above purification unit includes at least one selected from the group consisting of a scrubber, an adsorption tower, and a PSA (Pressure Swing Adsorption).

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