Method and system for producing hydrogen

Abstract

The present disclosure relates to a method and a system for producing hydrogen, wherein the method comprises the steps of: (S1) introducing a feed gas containing C1 to C4 hydrocarbons into a first reactor and performing dry reforming to produce a first mixed gas; (S2) introducing carbon dioxide and carbon into a second reactor and converting same into a second mixed gas containing carbon monoxide via a reverse Boudouard reaction; (S3) mixing the first mixed gas and the second mixed gas to prepare a third mixed gas; (S4) generating synthetic gas from the third mixed gas through a water gas conversion reaction; and (S5) separating carbon dioxide from the synthetic gas to obtain hydrogen, wherein the carbon dioxide separated in step (S5) is recycled to the second reactor.

Description

Hydrogen production method and system

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

[0002] 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.

[0003] 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, hydrogen yields from synthesis gas are low, making it difficult to increase yields.

[0004] 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.

[0005] Furthermore, conventional gasification processes significantly lower the yield of synthesis gas, which can be converted into high-value-added products, resulting in low productivity and limited utilization or commercialization. Furthermore, while reducing carbon dioxide emissions is desirable from an environmental perspective, conventional gasification process products contain carbon dioxide and solid coke in addition to hydrogen and carbon monoxide, posing a serious problem: increased carbon dioxide and solid coke emissions can actually contribute to further environmental pollution.

[0006] 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 in a gasification process and hydrogen obtained therefrom, while minimizing the generation of carbon dioxide and solid coke.

[0007] According to one aspect of the present disclosure, a method and system for producing hydrogen can be provided in which the yield of hydrogen production is significantly improved.

[0008] 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.

[0009] In addition, according to another aspect of the present disclosure, a method and system for producing hydrogen can be provided that can minimize the generation of carbon dioxide and solid coke.

[0010] According to one aspect of the present disclosure, no residual gas may be generated during hydrogen production.

[0011] Additionally, according to another aspect of the present disclosure, the catalyst can be regenerated to perform a continuous dual circulation fluidized bed reaction.

[0012] The present disclosure provides a method for producing hydrogen, comprising the steps of: (S1) introducing a feed gas containing C1 to C4 hydrocarbons into a first reactor and dry reforming the same to produce a first mixed gas; (S2) introducing carbon dioxide and carbon into a second reactor and converting the same into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction; (S3) mixing the first mixed gas and the second mixed gas to produce a third mixed gas; (S4) producing a synthesis gas from the third mixed gas through a water gas shift reaction; and (S5) separating carbon dioxide from the synthesis gas to obtain hydrogen; wherein the carbon dioxide separated in step (S5) is recycled to the second reactor.

[0013] According to one embodiment of the present disclosure, the hydrogen production method may further include a step of purifying the first mixed gas or the second mixed gas.

[0014] According to one embodiment of the present disclosure, the purification may be performed in at least one selected from the group consisting of a scrubber and an adsorption tower.

[0015] According to one embodiment of the present disclosure, the step (S2) may be one in which carbon is supplied from an external source or carbon generated in the step (S1) is used.

[0016] According to one embodiment of the present disclosure, the step (S1) or (S2) may be performed under a composite catalyst in which an active metal is supported on a support.

[0017] According to one embodiment of the present disclosure, the active metal may include one or more selected from the group consisting of nickel, vanadium, iron, platinum, palladium, and ruthenium.

[0018] According to one embodiment of the present disclosure, the support may include at least one selected from the group consisting of silica, alumina, silica-alumina, clay, carbon, zirconia, titania, zeolite, SAPO and ALPO.

[0019] According to one embodiment of the present disclosure, the step (S2) may be performed at a temperature of 600 to 1000°C and a pressure of 50 to 500 KPa.

[0020] In addition, the present disclosure provides a hydrogen production system including a first reactor for producing a first mixed gas by dry reforming a feed gas containing C1 to C4 hydrocarbons under a catalyst; a second reactor for converting carbon dioxide and carbon into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction; a gas mixing unit for producing a third mixed gas by mixing the first mixed gas and the second mixed gas; a synthesis gas production unit for converting the third mixed gas into a synthesis gas through a water gas shift reaction; a carbon dioxide separation unit for separating carbon dioxide from the synthesis gas to obtain hydrogen; and a carbon dioxide recirculation line for recycling carbon dioxide separated in the carbon dioxide separation unit to the second reactor.

[0021] According to one embodiment of the present disclosure, the first reactor may be a first fluidized bed reactor, and the second reactor may be a second fluidized bed reactor.

[0022] According to one embodiment of the present disclosure, the hydrogen production system further includes a cyclone connected between the first fluidized bed reactor and the gas mixing 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 separates a first mixed gas and a catalyst discharged from the first fluidized bed reactor, supplies the first mixed gas to the gas mixing unit, and supplies the catalyst to the second fluidized bed reactor.

[0023] According to one embodiment of the present disclosure, the hydrogen production system may further include a purification unit for purifying the first mixed gas or the second mixed gas.

[0024] According to one embodiment of the present disclosure, the purification unit may include at least one selected from the group consisting of a scrubber and an adsorption tower.

[0025] A hydrogen production method and system according to one embodiment of the present disclosure can significantly improve the production yield of hydrogen.

[0026] A hydrogen production method and system according to another embodiment of the present disclosure can significantly improve process efficiency.

[0027] A hydrogen production method and system according to another embodiment of the present disclosure can minimize the generation of carbon dioxide and solid coke.

[0028] A hydrogen production method and system according to one embodiment of the present disclosure may not generate residual gas during hydrogen production.

[0029] 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.

[0030] A hydrogen production method and system according to another embodiment of the present disclosure can produce hydrogen in an eco-friendly manner.

[0031] FIG. 1 is a schematic diagram showing a hydrogen production system according to one embodiment of the present disclosure.

[0032] FIG. 2 is a schematic diagram showing a hydrogen production system including a catalyst circulation process according to one embodiment of the present disclosure.

[0033] 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.

[0034] 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.

[0035] As used herein, the singular forms of terms may be construed to include the plural forms as well, unless otherwise specified.

[0036] 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.

[0037] 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.

[0038] The unit of % used in this specification without special mention means weight % unless otherwise defined.

[0039] In this specification, “A to B” means “A or more and B or less” unless otherwise specifically defined.

[0040] In this specification, “synthesis gas” means a mixed gas containing hydrogen and carbon monoxide, and may include carbon dioxide, etc.

[0041] The term "C" in this specification A -C B " means "the number of carbon atoms is greater than or equal to A and less than or equal to B".

[0042] 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.

[0043] 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 process efficiency. In addition, there has been a problem that a large amount of carbon dioxide and solid coke are emitted during the process, causing environmental pollution. In addition, the conventional gasification process has a problem that the production yield of synthesis gas is significantly low and the production yield of hydrogen is low, resulting in low productivity. Therefore, the inventors of the present disclosure have devised a hydrogen production method and system that can achieve a significantly high hydrogen yield while minimizing the generation of carbon dioxide and solid coke.

[0044] The present disclosure provides a method for producing hydrogen, comprising the steps of (S1) introducing a feed gas containing C1 to C4 hydrocarbons into a first reactor and dry reforming the same to produce a first mixed gas; (S2) introducing carbon dioxide and carbon into a second reactor and converting the same into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction; (S3) mixing the first mixed gas and the second mixed gas to produce a third mixed gas; (S4) producing a synthesis gas from the third mixed gas through a water gas shift reaction; and (S5) separating carbon dioxide from the synthesis gas to obtain hydrogen; wherein the carbon dioxide separated in step (S5) is recycled to the second reactor.

[0045] The hydrogen production method according to the present disclosure can efficiently convert a feed gas containing C1 to C4 hydrocarbons into synthesis gas compared to a conventional gasification process, thereby maximizing the yield of high value-added hydrogen converted from the synthesis gas. In addition, carbon dioxide and / or solid carbon or solid coke generated during the process of producing the synthesis gas can be recycled to the second reactor and converted into raw materials for the synthesis gas, thereby minimizing the generation of carbon dioxide and solid coke or solid carbon during the hydrogen production process, thereby preventing environmental pollution.

[0046] In one embodiment according to the present disclosure, the feed gas may comprise at least one selected from the group consisting of methane, hydrogen, carbon monoxide and carbon dioxide.

[0047] As an example of increasing the methane content in the feed gas, the feed gas may further include one or more selected from the group consisting of landfill gas, shale gas, refinery exhaust gas, and biogas. The landfill gas, shale gas, refinery exhaust gas, and biogas described above contain methane and carbon dioxide in an amount of 40% by volume or more, specifically, 50% by volume or more. Therefore, since the feed gas further contains the above-described gases, there is an effect of further improving the production yield of synthesis gas through subsequent processes such as dry reforming and reverse Budar reaction.

[0048] The above C1 to C4 hydrocarbons may include, but are not limited to, at least one selected from the group consisting of methane, ethane, propane and butane.

[0049] In one embodiment according to the present disclosure, the C / O element ratio of the feed gas may be, as an upper limit, 0.15 or less, 0.1 or less, or 0.08 or less, and as a lower limit, 0.01 or more, 0.03 or more, or 0.05 or more, specifically, 0.01 to 0.15, and more specifically, 0.03 to 0.1.

[0050] The method for producing hydrocarbons according to the present disclosure enables a smooth methane reforming reaction even when the feed gas contains a relatively high C / O element ratio within the above-described range. Specifically, since the catalyst used in the methane 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 dry reforming of methane.

[0051] The above step (S1) is a step of introducing a feed gas containing C1 to C4 hydrocarbons into a first reactor and dry reforming it to produce a first mixed gas. The above step (S1) may involve a dry reforming reaction according to the following reaction scheme 1.

[0052] [Reaction Formula 1]

[0053] CH4+ CO2→ 2CO + 2H2 (dry reforming reaction)

[0054] By performing the dry reforming reaction in step (S1), the methane reforming efficiency can be improved, thereby increasing the hydrocarbon yield. Specifically, the dry reforming process can more smoothly perform the catalytic reaction of synthesis gas, which is a subsequent process, because the ratio of the products, hydrogen and carbon monoxide, is close to 1:1.

[0055] The dry reforming reaction of the above step (S1) can be performed at a temperature of 600 to 1400°C and a pressure of 30 to 2000 KPa.

[0056] The above (S1) step can be operated without a catalyst, but can be operated using a catalyst to increase the reaction conversion rate at a low temperature of 600 to 700°C.

[0057] The catalyst of the above step (S1) may be a composite catalyst in which an active metal is supported on a support. The active metal may include one or more selected from the group consisting of nickel, vanadium, iron, platinum, palladium, and ruthenium. Typically, nickel, vanadium, or iron may be used as the active metal, and in cases where the raw material, such as organic waste, has a low impurity content during the heat treatment process, a precious metal such as platinum, palladium, or ruthenium may be used.

[0058] In one example, 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, clay, carbon, zirconia, titania, SAPO, and ALPO.

[0059] The dry reforming reaction of the above step (S1) may be performed in a first fixed bed reactor or a first fluidized bed reactor.

[0060] By performing the dry reforming reaction of the above step (S1) 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 yield of hydrogen.

[0061] In addition, since the step (S1) is performed in a fluidized bed reactor, the catalyst used in the methane reforming reaction can be regenerated and then supplied to a subsequent reverse catalytic reaction process, thereby forming a cyclic process. Since the methane reforming reaction is performed in a dry manner in the step (S1), coke may accumulate in the catalyst, which may deactivate the catalytic reaction. However, since the step (S1) is performed in a fluidized bed reactor, thereby enabling a cyclic process of regenerating and resupplying the catalyst, there is an advantage in that a continuous reforming reaction is possible even when methane is dry reformed.

[0062] In one embodiment according to the present disclosure, the hydrogen production method may further include a step of purifying the first mixed gas or the second mixed gas.

[0063] 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 first mixed gas or the second mixed gas can be removed, and when the first mixed gas or the second mixed gas is passed through a ceramic filter or a dust collecting filter, impurities such as tar and dust can be removed. In particular, carbon such as tar contained in the first mixed gas and separated through purification can be introduced into the second reactor and used as a carbon source for the reverse Buddha reaction.

[0064] In one embodiment according to the present disclosure, the purification may be performed by at least one selected from the group consisting of a scrubber and an adsorption tower. By performing the purification through the scrubber, Cl, N, and S impurities can be removed. By performing the purification through the adsorption tower, metal impurities such as Hg and As can be removed. The scrubber or the adsorption tower can perform the purification using a conventional method.

[0065] In one embodiment according to the present disclosure, step (S2) is a step of introducing carbon dioxide and carbon into a second reactor and converting them into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction. In step (S5), which will be described later, the separated carbon dioxide is introduced into the second reactor and further converted into carbon monoxide through a reverse Boudouard reaction, thereby preventing environmental pollution 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.

[0066] [Reaction Formula 2]

[0067] C + CO2→ 2CO

[0068] The above step (S2) can be performed at a temperature of 600 to 1000°C and a pressure of 50 to 500 KPa.

[0069] In one embodiment according to the present disclosure, step (S2) may be performed by supplying carbon from an external source or using carbon generated in step (S1). Specifically, in one embodiment according to the present disclosure, the carbon source for the reverse Buddha reaction in step (S2) may be the catalyst on which coke supplied in step (S1) is deposited. In addition, the process may be performed by supplying carbon, such as activated carbon or graphite, from an external source, as needed. The graphite may be high purity graphite.

[0070] The reverse reaction of the above step (S2) may be performed in a second fixed bed reactor or a second fluidized bed reactor.

[0071] Since the reverse Buta reaction of step (S2) is performed in the second fixed bed reactor, the carbon dioxide separated in step (S5) described below can be converted into carbon monoxide with high efficiency. In addition, when the present disclosure uses the first fixed bed dry reforming reactor in step (S1), 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 (S2).

[0072] When the dry reforming reaction of the above step (S1) is performed in the first fluidized bed reactor, the first 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. The catalyst on which coke has been deposited in the second fluidized bed reactor may be regenerated by reacting as a carbon source for the reverse Buta reaction, and the regenerated catalyst may be supplied back to the first fluidized bed reactor through the catalyst recirculation line. By utilizing 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, environmental pollution can be reduced, and the process can be performed economically.

[0073] That is, according to one embodiment of the present disclosure, the yield of synthesis gas can be maximized and emissions of carbon dioxide and solid carbon can be minimized through the dry reforming reaction and the reverse Buta reaction, while the first fluidized bed reactor and the second fluidized bed reactor in which the dry reforming reaction and the reverse Buta reaction are performed form a circulation process, thereby simultaneously implementing continuous and economical process operation according to catalyst regeneration.

[0074] 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 one or more selected from the group consisting of nickel, vanadium, iron, platinum, palladium, and ruthenium. Typically, nickel, vanadium, or iron may be used as the active metal, and in cases where the raw material, such as organic waste, has a low impurity content during the heat treatment process, a precious metal such as platinum, palladium, or ruthenium may be used.

[0075] In one embodiment according to the present disclosure, the support used in the catalyst of the step (S2) 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, clay, carbon, zirconia, titania, SAPO, and ALPO.

[0076] In one embodiment according to the present disclosure, step (S3) may be a step of producing a third mixed gas by mixing the first mixed gas and the second mixed gas. The third mixed gas may include at least one selected from the group consisting of hydrogen, carbon monoxide, and carbon dioxide. Additionally, the third mixed gas may further include unreacted methane from step (S1).

[0077] In one embodiment according to the present disclosure, step (S4) 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.

[0078] [Chemical Formula 3]

[0079] CO + H2O → H2 + CO2

[0080] The above synthesis gas refers to a mixed gas containing hydrogen and carbon monoxide, and may additionally contain carbon dioxide.

[0081] The above water gas shift reaction can be performed under a catalyst selected from the group consisting of Cu, Zn, Fe and Cr as an active metal.

[0082] 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.

[0083] 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.

[0084] In one embodiment according to the present disclosure, the step (S5) is a step of obtaining hydrogen by separating carbon dioxide from the synthesis gas. In one embodiment according to the present disclosure, the method for separating the synthesis gas into a gas containing carbon dioxide and hydrogen is not limited to any known method, but the present disclosure allows separation using a carbon dioxide separation unit. Specifically, 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 binding 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 synthesis gas can be separated into a gas containing carbon dioxide and hydrogen.

[0085] According to another embodiment of the present disclosure, the carbon dioxide separation can be performed through a carbon dioxide separation membrane.

[0086] In another embodiment according to the present disclosure, the carbon dioxide separation unit may be a CC unit (Carbon capture unit). When the CC unit is used to separate carbon dioxide, the CC 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 CC unit (Carbon capture unit) may be used to separate synthesis gas into a gas containing carbon dioxide and hydrogen.

[0087] In one embodiment according to the present disclosure, the carbon dioxide separated in the step (S5) may be 100% carbon dioxide, or may be in the form of a mixed gas containing some other gases. In this case, the mixed gas containing some of the other gases may contain carbon dioxide in a lower limit of 40% by volume or more, 50% by volume or more, or 60% by volume or more, and an upper limit of 99% by volume or less, 90% by volume or less, 80% by volume or less, or 70% by volume or less. In the carbon dioxide separation unit, when capturing and separating carbon dioxide, the regeneration tower where the carbon dioxide is separated from the adsorbent must be designed with a high stage in order to separate the carbon dioxide with high purity, which consumes more energy. Therefore, since the mixed gas containing some of the other gases contains carbon dioxide in the above-described range, the carbon dioxide separation process can be performed under slightly milder conditions.

[0088] The carbon dioxide separated in step (S5) may be recycled to the second reactor. Rather than being discharged externally, the carbon dioxide separated in step (S5) may be recycled to the second reactor, thereby reducing carbon dioxide emissions during hydrogen production and achieving a higher hydrogen yield. The carbon dioxide separated in step (S5) may be directly fed into the second reactor, or mixed with carbon dioxide supplied externally or from another process before being fed into the second reactor.

[0089] 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.

[0090] The present disclosure provides a hydrogen production system comprising: a first reactor for producing a first mixed gas by dry reforming a feed gas containing C1 to C4 hydrocarbons under a catalyst; a second reactor for converting carbon dioxide and carbon into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction; a gas mixing unit for producing a third mixed gas by mixing the first mixed gas and the second mixed gas; a synthesis gas production unit for converting the third mixed gas into a synthesis gas through a water gas shift reaction; a carbon dioxide separation unit for separating carbon dioxide from the synthesis gas to obtain hydrogen; and a carbon dioxide recirculation line for recycling carbon dioxide separated in the carbon dioxide separation unit to the second reactor.

[0091] The hydrogen production system (1) according to the present disclosure can efficiently and economically produce synthesis gas and hydrogen by performing a dry reforming reaction and a reverse Budar reaction simultaneously, and can significantly reduce the amount of carbon dioxide and solid coke emitted.

[0092] Referring to FIG. 1, feed gas (100) is fed into a first reactor (20) and converted into a first mixed gas (110) through a dry reforming reaction. Carbon dioxide and carbon are fed into a second reactor (40) and converted into a second mixed gas (200) containing carbon monoxide through a reverse Boudouard reaction. The first mixed gas (110) and the second mixed gas (200) are mixed in a gas mixing unit (50) to produce a third mixed gas (220). The third mixed gas (220) is converted into a synthesis gas (230) through a water gas shift reaction in the synthesis gas generating unit (60). Carbon dioxide included in the synthesis gas (230) is separated in the carbon dioxide separation unit (80), and a gas containing hydrogen can be obtained. The carbon dioxide separated in the carbon dioxide separation unit (80) is recycled to the second reactor (40) through the carbon dioxide recirculation line (500) and used again as a raw material for the reverse reaction in the second reactor (40).

[0093] 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.

[0094] In one embodiment according to the present disclosure, referring to FIG. 2, the hydrogen production system (1) further includes a cyclone (70) connected between the first fluidized bed reactor (20) and the gas mixing unit (50); a catalyst supply line (600) connecting the cyclone (70) and the second fluidized bed reactor (40); and a catalyst recirculation line (700) connecting the second fluidized bed reactor (40) and the first fluidized bed reactor (20). The cyclone (70) separates the first mixed gas (110) discharged from the first fluidized bed reactor (20) and the catalyst, supplies the first mixed gas (110) to the gas mixing unit (50), and supplies the catalyst to the second fluidized bed reactor (40).

[0095] 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 second fluidized bed reactor can utilize the coke-deposited catalyst supplied from the first fluidized bed reactor without the need for a separate carbon source for performing the reverse Buta reaction, thereby enabling more economical process operation and minimizing environmental pollution by eliminating the emission of solid coke.

[0096] In one embodiment of the present disclosure, the hydrogen production system may further include a purification unit for purifying the first mixed gas or the second mixed gas. In addition, 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).

[0097] The above purification unit includes a sprinter that sprays liquid to contact the first mixed gas or the second mixed gas 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, or can remove impurities such as tar using a ceramic filter, but is not limited thereto, and a conventional purification method can also be used.

[0098] 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.

[0099] [Example 1]

[0100] Feed gas containing H221.52 mol%, CO10.76 mol%, CO227.72 mol% and CH440 mol% was introduced into the first fluidized bed reactor and treated at 750°C, 2.0 L / g under the presence of a Ni / Al2O3 catalyst. cat ·The first mixed gas was produced through dry reforming under the operating conditions of h.

[0101] The first mixed gas contained H252.92 mol%, CO30.34 mol%, CO27.86 mol%, and CH48.87 mol%.

[0102] Carbon dioxide and carbon were fed into the second fluidized bed reactor and converted into a second mixed gas containing carbon monoxide through a reverse Buddha reaction. Carbon dioxide separated from the carbon dioxide separation unit was supplied to the second fluidized bed reactor. In addition, the spent Ni / Al2O3 catalyst separated from the cyclone after the dry reforming reaction in the first fluidized bed reactor was supplied to the second fluidized bed reactor through a catalyst supply line. The coke deposited on the spent catalyst was used as carbon. The spent Ni / Al2O3 catalyst was heated at 900°C, 300 kPa, and a throughput of 2.0 L / g. cat · Under the h operating conditions, a reverse reaction was performed to generate a second mixed gas containing carbon monoxide. The Ni / Al2O3 spent catalyst was regenerated and supplied to the first fluidized bed reactor through the catalyst recirculation line.

[0103] The first mixed gas and the second mixed gas were introduced into a gas mixing unit and mixed to produce a third mixed gas. The third mixed gas contained H245.98 mol%, CO39.47 mol%, CO26.83 mol%, and CH47.71 mol%.

[0104] The third mixed gas is fed into the synthesis gas generation unit and is produced under the Cu / Zn / Al2O3 catalyst at 250 ℃, 35 bar, throughput 1.4 L / g cat· Synthesis gas was produced through a water-gas shift reaction performed under operating conditions of h. The synthesis gas contained H251.33 mol%, CO25.65 mol%, CO216.08 mol%, and CH46.94 mol%.

[0105] The above synthesis gas was introduced into an amine scrubber. Specifically, the synthesis gas was introduced into a first amine scrubber, where carbon dioxide was captured in a 30 wt% amine aqueous solution containing MEA (Monoethanolamine) dissolved therein at 40°C, and the gas containing uncaptured hydrogen was recovered. The amine aqueous solution from the amine scrubber was introduced into an amine regeneration tower, where it was separated into the amine aqueous solution and carbon dioxide at 100°C, and the carbon dioxide was recycled to the second fluidized bed reactor.

[0106] The hydrogen production based on the same feed and the CO2 and solid carbon generation per mole of synthesis gas hydrogen are shown in Table 1 below.

[0107] [Comparative Example 1]

[0108] The same procedure as Example 1 was followed, except that the reverse reaction was not performed in Example 1, so that a second mixed gas was not generated, and the carbon dioxide captured in the amine scrubber was not recycled for the reverse reaction. The ratio of hydrogen to carbon monoxide in the synthesis gas was maintained the same as in Example 1.

[0109] The hydrogen production based on the same feed and the CO2 and solid carbon generation per mole of synthesis gas hydrogen are shown in Table 1 below.

[0110] Example 1 Comparative Example 1 Hydrogen production (kmol / h) (based on the same feed) 94.197 9.69 CO2 and solid carbon production per mole of synthesis gas hydrogen (mol / mol) 0.198 0.324

[0111] As in Comparative Example 1 above, when the reverse Buta reaction was not performed, the second mixed gas was not generated, and the carbon dioxide captured in the amine scrubber was not recycled for the reverse Buta reaction, it was confirmed that 79.69 kmol / h of hydrogen was produced based on the same feed, and 0.324 mol of carbon dioxide and solid carbon were generated per mol of synthesis gas hydrogen.

[0112] On the other hand, when the reverse Buta reaction was performed as in Example 1 and the carbon dioxide captured in the amine scrubber was recycled for the reverse Buta reaction, it was confirmed that 94.19 kmol / h of hydrogen was produced based on the same feed, and 0.198 mol of carbon dioxide and solid carbon were generated per mol of synthesis gas hydrogen. That is, it was confirmed that the loss of carbon dioxide and solid carbon generated in the entire process was significantly reduced. In addition, it was confirmed that the hydrogen production amount also significantly increased compared to Comparative Example 1 because the carbon dioxide and solid carbon that were not lost were converted to carbon monoxide and reacted with water introduced in the water gas shift reaction to increase the hydrogen production yield.

[0113] The above description is merely an example of applying the principles of the present disclosure, and other configurations may be further included without departing from the scope of the present disclosure.

[0114] 1 Hydrogen production system

[0115] 20 Reactor 1

[0116] 40 Second reactor

[0117] 50 gas mixing units

[0118] 60 synthesis gas generation units

[0119] 70 cyclones

[0120] 80 carbon dioxide separation units

[0121] 100 feed gas

[0122] 110 First mixed gas

[0123] 200 Second mixed gas

[0124] 220 Third mixed gas

[0125] 230 Syngas

[0126] 500 carbon dioxide recycling lines

[0127] 600 catalyst supply lines

[0128] 700 catalyst recirculation line

Claims

1. (S1) A step of introducing a feed gas containing C1 to C4 hydrocarbons into a first reactor and dry reforming the feed gas to produce a first mixed gas; (S2) A step of introducing carbon dioxide and carbon into a second reactor and converting them into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction; (S3) A step of producing a third mixed gas by mixing the first mixed gas and the second mixed gas; (S4) a step of generating synthesis gas through a water gas conversion reaction from the third mixed gas; and (S5) A method for producing hydrogen, comprising a step of obtaining hydrogen by separating carbon dioxide from the above synthesis gas, A hydrogen production method, wherein the carbon dioxide separated in the above step (S5) is recycled to the second reactor.

2. In paragraph 1, A hydrogen production method, wherein the above hydrogen production method further includes a step of purifying the first mixed gas or the second mixed gas.

3. In paragraph 2, A method for producing hydrogen, wherein the above purification is performed in at least one selected from the group consisting of a scrubber and an adsorption tower.

4. In paragraph 1, A method for producing hydrogen, wherein the above step (S2) supplies carbon from an external source or uses carbon generated in the above step (S1).

5. In paragraph 1, A method for producing hydrogen, wherein the above step (S1) or (S2) is performed under a composite catalyst in which an active metal is supported on a support.

6. In paragraph 5, 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.

7. In paragraph 6, A method for producing hydrogen, wherein the support comprises at least one selected from the group consisting of silica, alumina, silica-alumina, clay, carbon, zirconia, titania, zeolite, SAPO and ALPO.

8. In paragraph 1, A method for producing hydrogen, wherein the above step (S2) is performed at a temperature of 600 to 1000°C and a pressure of 50 to 500 KPa. A first reactor for generating a first mixed gas by dry reforming a feed gas containing 9.C1 to C4 hydrocarbons under a catalyst; A second reactor that converts carbon dioxide and carbon into a second mixed gas containing carbon monoxide through a reverse Boudouard reaction; A gas mixing unit that mixes the first mixed gas and the second mixed gas to produce a third mixed gas; A synthesis gas generation unit that converts the third mixed gas into synthesis gas through a water gas shift reaction; A carbon dioxide separation unit that separates carbon dioxide from the above synthesis gas to obtain hydrogen; and A hydrogen production system, comprising a carbon dioxide recirculation line for recirculating carbon dioxide separated from the carbon dioxide separation unit to the second reactor.

10. In paragraph 9, A hydrogen production system, wherein the first reactor is a first fluidized bed reactor and the second reactor is a second fluidized bed reactor.

11. In paragraph 10, The above hydrogen production system, A cyclone connected between the first fluidized bed reactor and the gas mixing 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 cyclone separates the first mixed gas and catalyst discharged from the first fluidized bed reactor, supplies the first mixed gas to a gas mixing unit, and supplies the catalyst to a second fluidized bed reactor.

12. In paragraph 9, A hydrogen production system, wherein the above hydrogen production system further includes a purification unit for purifying the first mixed gas or the second mixed gas.

13. In paragraph 12, A hydrogen production system, wherein the purification unit comprises at least one selected from the group consisting of a scrubber and an adsorption tower.

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