A method and system for preparing synthesis gas by coupling CO2 / H2O decomposition and methane reforming

Abstract

The application discloses a method and system for preparing synthesis gas by coupling CO2 / H2O decomposition and methane reforming, and relates to the technical field of thermochemical conversion and synthesis gas preparation. The application adopts a two-step thermochemical cycle. Oxygen storage material is oxidized to form a reduced state by thermal decomposition, and the thermal energy of the released gas and the residual heat after cooling drive the dry / wet reforming of methane to generate CO and / or H2. The reduced oxygen storage material is reacted with CO2 and / or H2O to generate CO and / or H2, and the oxidation state is restored at the same time. The mixture of the two-stage products obtains synthesis gas with an adjustable H2 / CO molar ratio of 0.5-5. The application improves the energy utilization rate by heat energy recovery coupling, avoids the risk of mixing O2 with synthesis gas, and is suitable for diversified downstream chemical and energy fields.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermochemical conversion and synthesis gas preparation, in particular to a method and system for preparing synthesis gas by coupling CO2 / H2O decomposition and methane reforming. BACKGROUND

[0002] For a long time, fossil energy represented by coal, oil and natural gas has promoted the rapid development of social economy, but its large-scale exploitation and utilization has caused increasingly serious environmental problems such as greenhouse effect. Developing clean, reliable and sustainable new energy and resource conversion technology has become a global consensus. Solar energy, as a renewable energy source that is inexhaustible, clean and pollution-free and not limited by region, has shown significant advantages in the field of driving CO2 and / or H2O conversion into chemical fuels that are easy to store and transport, and has become an important direction of energy transformation and low-carbon development.

[0003] Under this background, synthesis gas, as the core link in the field of energy and chemical industry, has become increasingly prominent in its strategic value. As a key industrial gas with flexible composition, synthesis gas has dual core attributes of energy carrier and chemical raw material: in the energy field, it can be efficiently converted into electricity, heat and transportation fuel, and is an important support for building a clean energy system; in the chemical industry, it is the core raw material for synthesizing ammonia, methanol, ethylene glycol and other basic chemicals and special chemical products, directly maintaining the industrial chain of modern chemical industry. What is particularly important is that the flexible control of the H2 / CO ratio in synthesis gas enables it to accurately match the different process requirements of the downstream, which fundamentally determines the efficiency and economy of the industrial process.

[0004] However, the current synthesis gas preparation technology still has significant limitations: the traditional coal-to-synthesis gas process relies on fossil fuel consumption, which not only has high energy consumption, but also produces a large amount of carbon emissions, which is contrary to the goal of carbon neutralization; in the existing synthesis gas preparation technology based on thermochemical decomposition of CO2 / H2O, the optimal temperatures of multi-step reactions differ significantly, resulting in difficulty in efficient utilization of high-temperature heat and waste heat in the cooling process, and serious energy loss; at the same time, if the methane reforming reaction is carried out alone, a large amount of energy needs to be consumed to maintain the reaction temperature, and the traditional process often has the safety risk of mixing O2 and synthesis gas, with complex process and poor integration. These problems greatly restrict the efficient, low-carbon and safe preparation of synthesis gas, and there is an urgent need for a new technology that can realize energy cascade utilization, compact process and low-carbon environmental protection. SUMMARY

[0005] The present application aims to provide a method and system for preparing synthesis gas by coupling CO2 / H2O decomposition and methane reforming, so as to solve the problems existing in the prior art. The present application can efficiently realize thermal conversion and coupled utilization of low-carbon resources, and is particularly suitable for providing upstream gas source for fuel or chemical product synthesis process based on synthesis gas with adjustable H2 / CO molar ratio. The method couples thermal recovery of two-step thermochemical CO2 / H2O decomposition and methane dry / wet reforming, significantly improves energy utilization efficiency, and effectively overcomes the problems of high energy consumption, harsh reaction conditions, and complex process flow in traditional gas preparation processes.

[0006] To achieve the above-mentioned object, the present application provides the following solutions.

[0007] The present application provides a method for preparing synthesis gas by coupling CO2 and / or H2O decomposition and methane reforming, comprising the following steps:

[0008] (1) thermally decomposing the oxygen storage material at a first temperature to release oxygen and form a reduced-state oxygen storage material;

[0009] (2) using the heat energy carried by the gas generated in step (1) and the waste heat recovered in the cooling process to drive methane dry reforming and / or wet reforming to generate intermediate products CO and / or H2;

[0010] (3) introducing CO2 and / or H2O gas into the reduced-state oxygen storage material in step (1) to react at a second temperature to generate CO and / or H2;

[0011] (4) mixing the product gas of step (2) and step (3) to obtain synthesis gas with adjustable H2 / CO molar ratio.

[0012] As a further preferred embodiment of the present application, the method comprises the following steps:

[0013] (a) introducing inert gas or nitrogen into a reactor filled with oxygen storage material to cause thermal decomposition of the oxygen storage material at a first temperature condition, release oxygen, generate partially reduced-state oxygen storage material, and discharge the heat energy carried by the gas to a methane reforming reactor;

[0014] (b) after the thermal decomposition reaction of the oxygen storage material is completed, reducing the temperature of the reactor to a second temperature, and the heat energy released during the cooling process is transported to the methane reforming reactor through the inert gas or nitrogen to provide reaction heat for methane dry reforming and / or wet reforming, and generate intermediate products CO and / or H2;

[0015] (c) stopping the inert gas or nitrogen gas from flowing into the reactor and instead flowing CO2 and / or H2O gas into the reactor, allowing the gas to react with the reduced oxygen storage material in a redox reaction to produce CO and / or H2, while the oxygen storage material recovers lattice oxygen to return to the oxidized state;

[0016] (d) collecting the gas produced in step (b) and step (c) to obtain the synthesis gas.

[0017] As a further preferred embodiment of the present application, the first temperature is 1100-1600℃ and the second temperature is 600-1100℃.

[0018] As a further preferred embodiment of the present application, the metal oxide comprises one or more of Fe, Ce, Co, Ni, La, Sr and Mn.

[0019] Preferably, the metal oxide is spinel type and / or perovskite type.

[0020] More preferably, the oxygen storage material is Fe-Ce or Fe-Mn based metal oxide.

[0021] As a further preferred embodiment of the present application, the inert gas is argon or helium.

[0022] As a further preferred embodiment of the present application, the molar ratio of H2 / CO in the synthesis gas is controlled to be between 0.5-5 by adjusting the molar ratio of CO2 to H2O.

[0023] As a further preferred embodiment of the present application, the temperature for the dry reforming and / or wet reforming of methane is 500-900℃.

[0024] As a further preferred embodiment of the present application, the oxygen storage material is further subjected to redox cycling in the reactor.

[0025] In a second aspect of the present application, a synthesis gas system for carrying out the above-mentioned CO2 and / or H2O decomposition and methane reforming coupling to prepare synthesis gas is provided, comprising:

[0026] a redox reactor for thermal decomposition and / or redox cycling of the oxygen storage material;

[0027] a methane reforming reactor for dry reforming and / or wet reforming of methane;

[0028] a heat recovery heat exchanger for transferring the heat energy released in the redox reactor to the methane reforming reactor;

[0029] The redox reactor and the methane reforming reactor are connected through the heat recovery heat exchanger.

[0030] As a further preferred embodiment of the present application, the redox reactor is a fixed bed, a fluidized bed or a rotary bed structure, and the methane reforming reactor is a tubular reactor.

[0031] For a multi-step thermochemical decomposition process, the optimal reaction temperature required by different steps usually varies greatly, resulting in a significant temperature difference between steps and causing a large amount of heat loss, which reduces the overall energy utilization efficiency of the system. The present application proposes an innovative method for preparing synthesis gas by coupling methane dry / wet reforming with two-step thermochemical decomposition, which effectively drives the methane dry / wet reforming reaction by fully utilizing the waste heat released during the temperature drop process, not only preparing synthesis gas with different components, but also significantly improving the thermal energy utilization efficiency of the system.

[0032] Two-step thermochemical decomposition CO2 or H2O technology is considered to be a promising energy conversion method. In this process, the oxygen storage material is thermally decomposed at high temperature to release lattice oxygen to generate O2, which is then passed into CO2 or / and H2O to react with the reduced oxygen storage material after cooling, generating CO or H2, while replenishing the lattice oxygen of the oxygen storage material to restore its oxidized state. Since O2 and CO (or H2) are generated at different times, their mixture is avoided, eliminating the need for gas separation and simplifying the process flow. In contrast, the methane dry / wet reforming reaction requires a lower temperature, which is suitable for driving by utilizing the waste heat released during the above high-temperature reaction stage, thereby significantly improving the energy utilization efficiency through coupling process and simplifying the structure and operation process of the reaction system.

[0033] Compared with the traditional coal-to-synthesis gas process, the present application has the following significant advantages: (1) using renewable concentrated solar energy or high-temperature industrial waste heat as a heat source, without the need for coal to participate in the reaction process, zero carbon emissions throughout, in line with the carbon neutralization goal; (2) the raw material sources are wide, including common gases such as CO2, H2O and methane, which are green, environmentally friendly and sustainable; (3) the process flow is compact, the reaction path is separated, avoiding the safety risk of mixing O2 and synthesis gas, and having good engineering integration and operation safety; (4) by flexibly adjusting the ratio of the gas introduced, the H2 / CO ratio in the synthesis gas can be controlled between 0.5~5, which can match the different process requirements of downstream methanol, synthetic ammonia and Fischer-Tropsch synthesis, etc.

[0034] The present application discloses the following technical effects:

[0035] (1) The present application realizes the full utilization of high-temperature waste heat by coupling two-step thermochemical decomposition with methane reforming, significantly improving the thermal energy utilization efficiency of the system;

[0036] (2) By separating the reaction path, the mixing of O2 and CO / H2 is avoided, greatly improving the safety of the system;

[0037] (3) The component ratio of the generated synthesis gas can be flexibly adjusted according to requirements, and diversified downstream chemical raw material requirements can be met. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0039] Figure 1 A CO2 / H2O decomposition and methane reforming coupling process system for generating synthesis gas is provided. DETAILED DESCRIPTION

[0040] The various exemplary embodiments of the present application will now be described in detail, which should not be considered as limiting the present application, but should be understood as a more detailed description of some aspects, characteristics and embodiments of the present application.

[0041] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value in the stated range, and any other stated value or intermediate value in the stated range, is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In the case of conflict between the content of this specification and that of any document incorporated herein by reference, the content of this specification prevails.

[0043] Many modifications and variations of the present application described in the specification can be made without departing from the scope or spirit of the present application, which will be apparent to those skilled in the art. Other implementations of the present application will be apparent to those skilled in the art from the specification. The specification and examples of the present application are merely illustrative.

[0044] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean "including but not limited to".

[0045] It should be noted that the present application does not describe in detail the conventional operation means in the art, and is not the focus of the present application.

[0046] The present application provides a method for preparing synthesis gas by coupling CO2 / H2O decomposition and methane reforming, comprising the following steps:

[0047] (1) High-temperature thermal reduction step: inert gas (such as argon, nitrogen or helium) is introduced into a redox reactor filled with oxygen storage material, and the oxygen storage material is subjected to thermal decomposition reaction at a first temperature (preferably 1100-1600°C) to release oxygen and generate partially reduced oxygen storage material. Oxygen is discharged from the reactor with the inert gas, and the heat energy carried by the discharged gas is transferred to the methane reforming reactor.

[0048] The oxygen storage material includes metal oxides containing one or more of Fe, Ce, Co, Ni, La, Sr and Mn.

[0049] The metal oxide is spinel and / or perovskite.

[0050] Preferably, the oxygen storage material is a metal oxide containing one or two of Fe, Ce and Mn, such as Fe-Ce metal oxide or Fe-Mn metal oxide.

[0051] (2) Waste heat recovery and methane reforming step: after the thermal decomposition of the oxygen storage material is completed, the reactor is lowered to a second temperature (preferably 600-1100°C). The heat energy carried by the discharged gas in the thermal reduction step and the heat energy released during the cooling process are transferred to the methane reforming reactor through the inert gas to provide reaction heat for dry reforming, wet reforming or a combination of the two. Preferably, the methane reforming reaction is carried out at 500-900°C.

[0052] (3) CO2 / H2O decomposition step: stop introducing inert gas and introduce CO2 and / or H2O gas instead, which reacts with the reduced oxygen storage material to generate CO and / or H2, while the oxygen storage material replenishes lattice oxygen to restore to the oxidized state, completing the cycle.

[0053] (4) Synthesis gas mixing step: mix the synthesis gas generated by the methane reforming reaction in step (2) with the CO and / or H2 generated in step (3) to obtain the target synthesis gas. By adjusting the molar ratio and flow rate of CO2 and H2O introduced, the molar ratio of H2 to CO in the synthesis gas can be flexibly controlled between 0.5 and 5, meeting the subsequent diversified applications.

[0054] The present application provides a synthesis gas system for implementing the above-mentioned method for preparing synthesis gas by coupling CO2 / H2O decomposition and methane reforming, comprising:

[0055] a redox reactor for thermal decomposition and / or redox cycling of the oxygen storage material;

[0056] a methane reforming reactor for dry and / or wet reforming of methane;

[0057] a heat recovery heat exchanger for transferring heat energy released in the redox reactor reaction to the methane reforming reactor;

[0058] the redox reactor and the methane reforming reactor are connected by the heat recovery heat exchanger.

[0059] As a further preferred embodiment of the present application, the redox reactor is a fixed bed, fluidized bed or rotating bed structure, and the methane reforming reactor is a tubular reactor.

[0060] As a further preferred embodiment of the present application, the redox reactor comprises a reduction reactor and an oxidation reactor.

[0061] The synthesis gas system for implementing the above-mentioned CO2 / H2O decomposition and methane reforming coupling to prepare synthesis gas in the embodiment of the present application comprises: a redox reactor, a methane reforming reactor and a heat recovery heat exchanger; the redox reactor and the methane reforming reactor are connected by the heat recovery heat exchanger.

[0062] Example 1

[0063] CoFe2O4(20wt%) / CeO2 composite oxygen storage material is used as an oxidant catalyst in a two-step thermochemical cycle system for decomposing carbon dioxide and coupling with a dry methane reforming reaction to prepare synthesis gas, and the steps are as follows:

[0064] (a) Thermal decomposition and oxygen release stage: inert gas argon is introduced into the redox reactor filled with CoFe2O4(20wt%) / CeO2 composite oxygen storage material, the reactor is heated to 1400℃, the oxygen storage material is thermally decomposed to release oxygen and generate a partially reduced oxygen storage material; oxygen is discharged from the reactor with argon, and the high-temperature instant heat energy carried by the exhaust gas is transported to the methane reforming reactor through the heat recovery heat exchanger to provide an initial heating source.

[0065] (b) Temperature reduction and waste heat recovery and methane reforming stage: after the thermal decomposition reaction of the oxygen storage material is completed, the temperature of the redox reactor is reduced to 1000℃, and the waste heat released during the temperature reduction process is continuously transported to the heat recovery heat exchanger through argon, and is transferred to the methane reforming reactor through the heat recovery heat exchanger to provide reaction heat for the dry reforming reaction of CH4 and CO2 (generating H2 and CO), and at this time the temperature of the methane dry reforming reactor is maintained at 800℃.

[0066] (c) Oxidation reaction stage: stop the argon gas into the oxidation-reduction device, and replace it with CO2 gas, so that CO2 and the reduced CoFe2O4 / CeO2 have a redox reaction to generate CO; at the same time, the oxygen storage material restores to the oxidation state by replenishing the lattice oxygen, and a cycle is completed.

[0067] (d) Synthesis gas mixing stage: collect the H2 and CO generated by the dry reforming of methane in step (b), and mix them with the CO generated in step (c) to obtain the final synthesis gas.

[0068] In this embodiment, the system pressure is 0.1 MPa. The results show that the thermal efficiency of the methane dry reforming reaction system can reach 80%, and the overall thermal efficiency of the system is 45.5%, which is improved by 31.9% compared with the uncoupled reforming system (i.e. the oxygen storage material thermal decomposition and the methane dry reforming are not coupled by the heat energy recovery heat exchanger, and the methane reforming needs additional external heating). The molar ratio of H2 to CO in the generated synthesis gas is 1:2.44.

[0069] Comparative Example 1

[0070] The same oxygen storage material as in the embodiment is used, except that the waste heat released during the cooling process in the "waste heat recovery and methane reforming stage" is not recovered, and external heating is used.

[0071] CoFe2O4 (20wt%) / CeO2 composite oxygen storage material is used as the oxidized catalyst of the two-step thermochemical cycle system for decomposing carbon dioxide and coupling with the dry reforming of methane to prepare synthesis gas, and the steps are as follows:

[0072] (a) Thermal decomposition and oxygen release stage: inert gas argon is introduced into the oxidation-reduction reactor filled with CoFe2O4 (20wt%) / CeO2 composite oxygen storage material, the reactor is heated to 1400℃, the oxygen storage material is thermally decomposed to release oxygen and generate partially reduced oxygen storage material; the oxygen is discharged from the reactor with argon, and the high-temperature instantaneous heat energy carried by the discharged gas is transferred to the methane reforming reactor through the heat energy recovery heat exchanger to provide the initial heating heat source.

[0073] (b) Methane reforming stage: the dry reforming reaction conditions of CH4 and CO2 are the same as in Example 1, except that the waste heat released during the cooling process of the oxidation-reduction reactor is not recovered, and the energy required for the reforming reaction is driven by external heating.

[0074] (c) Oxidation reaction stage: stop the argon gas into the oxidation-reduction device, and replace it with CO2 gas, so that CO2 and the reduced CoFe2O4 / CeO2 have a redox reaction to generate CO; at the same time, the oxygen storage material restores to the oxidation state by replenishing the lattice oxygen, and a cycle is completed.

[0075] (d) Synthesis gas mixing stage: collect H2 and CO generated from the dry reforming of methane in step (b) and mix with CO generated in step (c) to obtain final synthesis gas.

[0076] In this embodiment, the system pressure is 0.1 MPa. The results show that the overall thermal efficiency of the uncoupled reforming system is only 34.5%, and the molar ratio of H2 to CO in the generated synthesis gas is 1:2.44.

[0077] Example 2

[0078] Ni 1.3 Fe 1.7 O4(15 wt%) / LaSrMnO3 composite oxygen storage material as the oxygen storage material of the two-step thermochemical cycle system, for decomposing carbon dioxide and coupling with the wet reforming reaction of methane to prepare synthesis gas, the specific operation is as follows:

[0079] (a) Thermal decomposition oxygen release stage: argon is introduced into the oxidation-reduction reactor filled with Ni 1.3 Fe 1.7 O4(15 wt%) / LaSrMnO3 composite oxygen storage material, heated to 1400℃, so that the oxygen storage material is thermally decomposed to release oxygen and generate partially reduced oxygen storage material; oxygen is discharged with argon, and the high-temperature instantaneous heat energy carried is transported to the methane reforming reactor through the heat recovery heat exchanger.

[0080] (b) Cooling and waste heat recovery and methane reforming stage: after thermal decomposition, the oxidation-reduction reactor is cooled to 1000℃, the cooling waste heat is transported to the heat recovery heat exchanger through argon, and is transmitted to the methane reforming reactor through the heat recovery heat exchanger to drive the wet reforming reaction of CH4 and H2O (generate H2 and CO), and the reaction temperature is maintained at 800℃.

[0081] (c) Oxidation reaction gas generation stage: stop introducing argon into the oxidation-reduction reactor and introduce CO2 gas instead, which reacts with the reduced oxygen storage material to generate CO, and the oxygen storage material returns to the oxidized state.

[0082] (d) Synthesis gas mixing stage: mix H2 and CO generated by wet reforming in step (b) with CO generated in step (c) to obtain synthesis gas.

[0083] In this embodiment, the thermal efficiency of the methane wet reforming system reaches 80.24%, and the total thermal efficiency of the system is about 45.6%, which is about 32% higher than that of the uncoupled system (i.e. the system in which the decomposition of the oxygen storage material and the wet reforming of methane do not realize heat energy coupling through the oxidation-reduction reactor and require external heating). The molar ratio of H2 to CO in the prepared synthesis gas is 1.82:1 (close to the ideal ratio of 2:1 for methanol synthesis). On this basis, the feed ratio can be further optimized for precise control.

[0084] Example 3

[0085] LaSrFe 0.5 Mn 0.5 O3 oxygen storage material as the oxygen storage material of the two-step thermochemical cycle system, is used for decomposing H2O and coupling with the dry reforming reaction of methane to prepare synthesis gas, and the specific operation is as follows:

[0086] (a) Thermal decomposition oxygen release stage: argon is introduced into the oxidation-reduction reactor filled with LaSrFe 0.5 Mn 0.5 O3 oxygen storage material, and the temperature is raised to 1350°C, so that the oxygen storage material is thermally decomposed to generate oxygen and reduced LaSrFe 0.5 Mn 0.5 O 3-δ ; the oxygen is discharged with argon, and the high-temperature instantaneous heat energy carried is transported to the methane reforming reactor through a heat recovery heat exchanger.

[0087] (b) Temperature reduction and waste heat recovery and methane reforming stage: after the thermal decomposition is completed, the oxidation-reduction reactor is cooled to 900°C, and the temperature reduction waste heat is transported to the methane reforming reactor (the temperature is maintained at 800°C) through argon, to drive the dry reforming reaction of CH4 and CO2 (H2 and CO are generated).

[0088] (c) Gas preparation stage of oxidation reaction: stop introducing argon into the oxidation-reduction reactor, and introduce H2O gas instead, to react with the reduced LaSrFe 0.5 Mn 0.5 O 3-δ to generate H2, and the oxygen storage material is supplemented with lattice oxygen to restore to the oxidation state.

[0089] (d) Synthesis gas mixing stage: mixing H2 and CO generated in step (b) dry reforming and H2 generated in step (c) to obtain the final synthesis gas.

[0090] In this example, the thermal efficiency of the dry reforming reaction system is about 87.5%, the total thermal efficiency of the system is 45.6%, which is increased by 32.5% compared with the uncoupling system (i.e. the system in which the decomposition of the oxygen storage material and the dry reforming of methane are not coupled by the heat recovery heat exchanger, and external heating is required), and the molar ratio of H2 to CO in the obtained synthesis gas is 1.1:1.

[0091] Example 4

[0092] CoFe2O4(25 wt%) / Ce 0.9 Mn 0.1 O2 composite oxygen storage material as the oxygen storage material of the two-step thermochemical cycle system, is used for decomposing H2O and coupling with the wet reforming reaction of methane to prepare synthesis gas, and the specific operation is as follows:

[0093] (a) Thermal decomposition oxygen evolution stage: argon gas is introduced into the redox reactor filled with CoFe2O4(25 wt%) / CeO2 composite oxygen storage material, and the temperature is raised to 1350℃, so that the oxygen storage material is thermally decomposed to generate oxygen and reduced oxygen storage material; the oxygen is discharged with argon, and the high-temperature instantaneous heat energy carried by the argon is transported to the methane reforming reactor through the heat recovery heat exchanger. 0.9 Mn 0.1 O2 composite oxygen storage material, and the temperature is raised to 1350℃, so that the oxygen storage material is thermally decomposed to generate oxygen and reduced oxygen storage material; the oxygen is discharged with argon, and the high-temperature instantaneous heat energy carried by the argon is transported to the methane reforming reactor through the heat recovery heat exchanger.

[0094] (b) Temperature reduction and waste heat recovery and methane reforming stage: after the thermal decomposition is completed, the redox reactor is cooled to 900℃, the waste heat during the cooling is transported to the heat recovery heat exchanger through argon, and then to the methane reforming reactor (the temperature is maintained at 800℃), to drive the wet reforming reaction of CH4 and H2O (H2 and CO are generated).

[0095] (c) Oxygen evolution stage: stop introducing argon into the redox reactor, and introduce H2O gas instead, to react with the reduced oxygen storage material to generate H2, and the oxygen storage material is restored to the oxidized state.

[0096] (d) Synthesis gas mixing stage: mixing H2 and CO generated in step (b) and H2 generated in step (c) to obtain the final synthesis gas.

[0097] In this embodiment, the thermal efficiency of the wet reforming system is 87.8%, the system thermal efficiency is 45.7%, which is improved by 32.6% compared with the uncoupled wet reforming system (i.e. the system without the participation of the heat recovery heat exchanger for heat energy coupling and the need for external heating), and the molar ratio of H2 to CO in the synthesis gas reaches 4.8:1, which is suitable for hydrogen-rich downstream processes (such as ammonia synthesis).

[0098] Figure 1 A CO2 / H2O decomposition and methane reforming coupled synthesis gas production process system is provided. In the process system, MeO Oxidized is an oxygen storage material, MeO reduced is a partially reduced oxygen storage material.

[0099] It should be noted that, Figure 1The CO2 / H2O decomposition and methane reforming coupled synthetic gas process system of the present application is only one specific form for example, which separates the oxidation-reduction reactor into a reduction reactor and an oxidation reactor and presents in the form of a fluidized bed, aiming to more clearly embody the process system of "thermal reduction- waste heat recovery- oxidation decomposition- synthetic gas mixing", and is not the only limitation of the process system of the present application; wherein, the reforming reactor is a methane reforming reactor. In actual application, as long as the core principle of coupling the two-step thermochemical cycle (oxygen storage material thermal decomposition oxygen release, CO2 / H2O reaction oxygen supplement) and the methane dry / wet reforming through heat energy recovery is followed, any deformation based on the principle belongs to the protection scope of the present application, including but not limited to: the oxidation-reduction reactor adopts other structural forms such as a fixed bed and a rotating bed, the heat energy recovery is realized through different types of heat exchange devices, the integration or separation of the reactor is adjusted, and the specific path optimization of the material flow and the heat flow, etc. These deformations have differences in specific structure or operation details, but all do not deviate from the technical concept disclosed by the present application, and thus all are included in the protection scope of the present application.

[0100] The above-described embodiments are only descriptions of the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various deformations and improvements of the technical solutions of the present application made by those skilled in the art should fall within the protection scope determined by the claims of the present application.

Claims

1. A method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming, characterized in that, Includes the following steps: (1) The oxygen storage material is thermally decomposed at the first temperature to release oxygen and form a reduced oxygen storage material; (2) Use the heat energy carried by the gas generated in step (1) and the residual heat recovered during the cooling process to drive dry reforming and / or wet reforming of methane to generate intermediate products CO and / or H2. (3) Introduce CO2 and / or H2O gas into the reduced oxygen storage material described in step (1), and react to generate CO and / or H2 at a second temperature; (4) Mix the product gases from steps (2) and (3) to obtain syngas.

2. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 1, characterized in that, Includes the following steps: (a) Inert gas or nitrogen is introduced into a reactor filled with oxygen storage material, causing the oxygen storage material to undergo thermal decomposition under a first temperature condition, releasing oxygen and generating partially reduced oxygen storage material. The heat energy carried by the discharged gas is transported to the methane reforming reactor. (b) After the thermal decomposition reaction of the oxygen storage material is completed, the temperature of the reactor is reduced to a second temperature. The heat energy released during the cooling process is transported to the methane reforming reactor through the inert gas or nitrogen to provide reaction heat for dry and / or wet reforming of methane, generating intermediate products CO and / or H2. (c) Stop introducing inert gas or nitrogen into the reactor and introduce CO2 and / or H2O gas instead, so that the gas reacts with the reduced oxygen storage material to generate CO and / or H2, while the oxygen storage material is replenished with lattice oxygen to restore it to the oxidized state. (d) Collect the gases generated in steps (b) and (c) and mix them to obtain syngas.

3. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 1, characterized in that, The first temperature is 1100–1600℃, and the second temperature is 600–1100℃.

4. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 1, characterized in that, The oxygen storage material includes one or more metal oxides selected from Fe, Ce, Co, Ni, La, Sr, and Mn.

5. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 2, characterized in that, The inert gas is argon or helium.

6. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 1, characterized in that, By adjusting the molar ratio of CO2 to H2O introduced, the molar ratio of H2 / CO in the synthesis gas is controlled to be between 0.5 and 5.

7. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 1, characterized in that, The temperature for the dry and / or wet reforming of methane is 500-900℃.

8. The method for preparing syngas by coupling CO2 and / or H2O decomposition with methane reforming according to claim 2, characterized in that, It also includes the step of the oxygen storage material undergoing a redox cycle in the reactor.

9. A syngas system for coupling CO2 and / or H2O decomposition with methane reforming to produce syngas according to any one of claims 1-8, characterized in that, include: A redox reactor for the thermal decomposition and / or redox cycle of the oxygen storage material; Methane reforming reactor for dry and / or wet reforming of methane; A heat recovery heat exchanger is used to transfer the heat energy released during the redox reactor reaction to the methane reforming reactor. The redox reactor and the methane reforming reactor are connected via the heat recovery heat exchanger.

10. The syngas system according to claim 9, characterized in that, The redox reactor is a fixed bed, fluidized bed, or rotating bed structure, and the methane reforming reactor is a tubular reactor.

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