A mixed ion conductor solid oxide electrolytic cell methane synthesis device and method

Abstract

The present invention discloses a device and method for synthesizing methane in a mixed ion conductor solid oxide electrolytic cell, which belongs to the field of methane synthesis. The technical scheme is as follows: a device for synthesizing methane in a mixed ion conductor solid oxide electrolytic cell, comprising a mixed ion conductor electrolytic cell, a first chamber and a second chamber separated from each other; the mixed ion conductor electrolytic cell comprises a first electrolytic cell and a second electrolytic cell; a catalyst is arranged in the second chamber; water vapor is input into the first chamber, and a first electrolysis reaction occurs in the first electrolytic cell to generate hydrogen and is discharged into the second chamber; carbon dioxide is input into the second chamber, and part of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell to generate carbon monoxide, and the carbon monoxide is discharged into the second chamber. The beneficial effects of the present invention are as follows: the device for synthesizing methane in a mixed ion conductor solid oxide electrolytic cell provided by the present invention promotes the methanogenic reaction to proceed in the forward direction, efficiently utilizes heat energy, has a simple structure, a compact layout, and strong practicality.

Description

Technical Field

[0001] The invention relates to the technical field of methane synthesis, and in particular to a device and method for synthesizing methane in a mixed ion conductor solid oxide electrolytic cell. Background Art

[0002] Global climate change has become one of the most important challenges facing the world today. Among them, carbon dioxide is one of the main greenhouse gases, and its release is closely related to human activities, especially the combustion of fossil fuels. The increase in carbon dioxide content in the atmosphere has led to a rise in global temperatures, resulting in a series of consequences such as frequent extreme weather, melting glaciers, and rising sea levels, which have had serious impacts on ecosystems, agriculture, human health, and social economy.

[0003] In the face of this challenge, it is crucial to develop technologies that can effectively reduce greenhouse gas emissions and achieve carbon recycling. The technology of synthesizing methane from carbon dioxide provides a feasible solution. By electrolyzing carbon dioxide and reacting with water vapor to produce methane, carbon dioxide can be converted into a fossil energy source and reused. This is of great significance for achieving energy conversion and storage and promoting energy structure transformation.

[0004] Invention patent CN105220172A published on January 6, 2016 relates to a tubular structure for directly converting a mixture of carbon dioxide and water vapor into a methane-rich fluid, and its preparation method and application. The tubular structure includes a high-temperature solid oxide electrolysis cell unit and a low-temperature methanation catalytic reactor unit. The carbon dioxide and water vapor mixture is co-electrolyzed in the high-temperature solid oxide electrolysis cell unit, and the mixed gas produced by the co-electrolysis is subjected to a methanation reaction in the low-temperature methanation catalytic reactor unit, thereby improving the conversion efficiency of carbon dioxide to methane. However, the reaction gas is a mixture of carbon dioxide and water vapor, and the presence of water vapor affects the conversion efficiency of the methanation reaction.

[0005] Patent CN107699915A published on February 16, 2018, involves a temperature-self-maintaining carbon dioxide and water vapor co-electrolysis device and its application method, including a reactor, a tubular solid oxide electrolysis cell, a fuel electrode chamber, and an air electrode chamber. The device thermally couples the electrolysis reaction with the methanation reaction, and can supply the heat generated by the exothermic process to the endothermic process, thereby achieving the effect of temperature self-maintenance and reducing energy consumption. However, the mixed raw gas introduced into the fuel electrode chamber is not conducive to the forward progress of the methanation reaction. Summary of the invention

[0006] In order to solve the above-mentioned problems in the prior art, the present invention provides a mixed ion conductor solid oxide electrolytic cell methane synthesis device which promotes the methanation reaction to proceed in the forward direction, efficiently utilizes thermal energy, has a simple structure, a compact layout, and is highly practical; and also provides a methane synthesis method with high methanation reaction efficiency and high methane conversion rate.

[0007] In order to achieve the above-mentioned invention object, the present invention provides a mixed ion conductor solid oxide electrolytic cell methane synthesis device, comprising a mixed ion conductor electrolytic cell, a first chamber located on one side of the mixed ion conductor electrolytic cell and a second chamber located on the other side of the mixed ion conductor electrolytic cell, wherein the first chamber is separated from the second chamber;

[0008] The mixed ion conductor electrolytic cell comprises a first electrolytic cell and a second electrolytic cell;

[0009] The first chamber includes a first input end and a first output end;

[0010] The second chamber comprises a second input end and a second output end; a catalyst is arranged in the second chamber;

[0011] Water vapor enters the first chamber from the first input end, the water vapor undergoes a first electrolysis reaction in the first electrolytic cell to generate hydrogen, and the hydrogen is discharged into the second chamber;

[0012] Carbon dioxide enters the second chamber from the second input end, and part of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell to generate carbon monoxide, which is then discharged into the second chamber.

[0013] Further, the first electrolytic cell is a proton conductor electrolytic cell;

[0014] The first electrolytic cell includes a first cathode layer and a first anode layer, the first anode layer is adjacent to the first chamber, and the first cathode layer is adjacent to the second chamber.

[0015] Further, the second electrolytic cell is an oxygen ion conductor electrolytic cell;

[0016] The second electrolytic cell includes a second cathode layer and a second anode layer, the second anode layer being adjacent to the first chamber, and the second cathode layer being adjacent to the second chamber.

[0017] Furthermore, an insulating member is provided between the ends of the first electrolytic cell and the second electrolytic cell that are close to each other.

[0018] Further, the mixed ion conductor electrolytic cell is tubular;

[0019] The first chamber is arranged inside the mixed ion conductor electrolytic cell and the second chamber is arranged outside the mixed ion conductor electrolytic cell, or the first chamber is arranged inside the mixed ion conductor electrolytic cell and the second chamber is arranged outside the mixed ion conductor electrolytic cell.

[0020] Further, the first electrolytic cell and the second electrolytic cell are arranged in sequence along the axial direction of the tubular mixed ion conductor electrolytic cell;

[0021] The first input end is close to the first electrolytic cell and far away from the second electrolytic cell, and the first output end is far away from the first electrolytic cell and close to the second electrolytic cell;

[0022] The second input end is far away from the first electrolytic cell and close to the second electrolytic cell, and the second output end is close to the first electrolytic cell and far away from the second electrolytic cell.

[0023] Furthermore, the carbon dioxide is pressurized and input into the second chamber.

[0024] Furthermore, the first chamber and the second chamber are separated by the mixed ion conductor electrolytic cell.

[0025] Furthermore, the mixed ion conductor electrolytic cell is disposed in a shell having an inner cavity, and the mixed ion conductor electrolytic cell divides the inner cavity into the first chamber and the second chamber.

[0026] A method for synthesizing methane, using the mixed ion conductor solid oxide electrolytic cell methane synthesis device, comprises the following steps:

[0027] Step 1: removing impurities in the second chamber and heating the mixed ion conductor electrolytic cell to a working temperature;

[0028] Step 2: inputting the carbon dioxide into the second chamber from the second input end, and inputting the water vapor into the first chamber from the first input end;

[0029] Step 3: The water vapor undergoes a first electrolysis reaction in the first electrolytic cell to generate the hydrogen, and the hydrogen is discharged into the second chamber; a portion of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell to generate the carbon monoxide, and the carbon monoxide is discharged into the second chamber;

[0030] Step 4: Another portion of the carbon dioxide and the hydrogen undergo a first methanation reaction in the second chamber under the action of the catalyst to generate methane, and the carbon monoxide and the hydrogen undergo a second methanation reaction in the second chamber under the action of the catalyst to generate methane; the carbon monoxide promotes the first methanation reaction; and the carbon dioxide promotes the second methanation reaction;

[0031] Step 5: The methane is discharged from the second chamber through the second output end.

[0032] The beneficial effects of the present invention are:

[0033] (1) The present invention uses a mixed ion conductor electrolytic cell to separate the reactants of the methanation reaction, carbon dioxide and water, so that only a small amount of water vapor is produced in the product during the methanation reaction, greatly reducing the water vapor content in the reactants. The low water vapor content can promote the methanation reaction to proceed in the forward direction and increase the methane yield.

[0034] (2) The present invention couples water electrolysis and carbon dioxide electrolysis with carbon dioxide methanation reaction and carbon monoxide methanation reaction, which can break through the chemical equilibrium constraint when only carbon dioxide methanation reaction exists, greatly improve the reaction efficiency and conversion rate of methanation, and increase the methane yield.

[0035] (3) The present invention utilizes countercurrent heat exchange between water and gas to realize the division of the high temperature zone and the medium and low temperature zone. Carbon dioxide is electrolyzed in the high temperature zone, so that the electrolytic cell operates at the optimal operating temperature, and the carbon dioxide electrolysis efficiency is high. The electrolysis of water and the occurrence of methanation reaction in the medium and low temperature zone are beneficial to promote the methanation reaction to proceed in the forward direction and increase the methane yield. At the same time, the electrolysis reaction absorbs the heat released by the methanation reaction, so that the heat energy is efficiently utilized and the energy consumption is reduced.

[0036] (4) The present invention pressurizes the second chamber for the methanation reaction by inputting carbon dioxide, thereby increasing the pressure balance and moving it in the positive direction, promoting the methanation reaction to proceed in the positive direction of reducing the amount of gaseous substances, and improving the methane yield.

[0037] (5) The present invention has a simple structure, compact layout, high practicality and economy;

[0038] (6) The method for synthesizing methane of the present invention has high methanation reaction efficiency and high methane conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of a partially cutaway structure of the present invention;

[0040] Figure 2 The present invention is a schematic structural diagram of a tubular mixed ion conductor electrolytic cell cut along the axis.

[0041] Among them, the figure markings are: 1, shell; 2, first chamber; 21, first input terminal; 22, first output terminal; 3, first electrolytic cell; 4, second electrolytic cell; 5, insulating member; 6, second chamber; 61, second input terminal; 62, second output terminal; 7, second anode layer; 8, second cathode layer; 9, second electrolyte layer; 10, first anode layer; 11, first cathode layer; 12, first electrolyte layer; 13, catalyst. DETAILED DESCRIPTION

[0042] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0043] See also Figure 1 , the embodiment of the present invention provides a mixed ion conductor solid oxide electrolytic cell methane synthesis device, comprising a mixed ion conductor electrolytic cell, a first chamber 2 located on one side of the mixed ion conductor electrolytic cell and a second chamber 6 located on the other side of the mixed ion conductor electrolytic cell, the first chamber 2 being separated from the second chamber 6;

[0044] The first chamber 2 is isolated from the second chamber 6, so that the water vapor in the reactants can be separated from the carbon dioxide, so that only a small amount of water vapor in the product is produced during the methanation reaction, which greatly reduces the water vapor content in the reactants. The low water vapor content can promote the methanation reaction to proceed in the forward direction, thereby increasing the methane yield. At the same time, separating water vapor from carbon dioxide can reduce the water vapor content in the product, reduce the difficulty of methane purification, and thus reduce the system cost.

[0045] The mixed ion conductor electrolytic cell comprises a first electrolytic cell 3 and a second electrolytic cell 4;

[0046] The first chamber 2 comprises a first input end 21 and a first output end 22;

[0047] The second chamber 6 includes a second input end 61 and a second output end 62; a catalyst 13 is disposed in the second chamber 6;

[0048] The water vapor enters the first chamber 2 from the first input end 21, and the water vapor undergoes a first electrolysis reaction in the first electrolytic cell 3 to generate hydrogen, which is then discharged into the second chamber 6;

[0049] The process of generating hydrogen by the first electrolysis reaction is:

[0050] H2O→2H + +0.5O2+2e 2- ,

[0051] 2H + +2e 2- →H2;

[0052] Carbon dioxide enters the second chamber 6 from the second input end 61, and part of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell 4 to generate carbon monoxide, which is then discharged into the second chamber 6;

[0053] The process of the second electrolysis reaction to generate carbon monoxide is:

[0054] CO2+2e 2- →CO+O 2- ;

[0055] For the convenience of distinguishing the carbon dioxide methanation reaction from the carbon monoxide methanation reaction, the carbon dioxide methanation reaction is called the first methanation reaction, and the carbon monoxide methanation reaction is called the second methanation reaction.

[0056] The other part of carbon dioxide and hydrogen that have not undergone the second electrolysis reaction undergo a first methanation reaction in the second chamber 6 under the action of the catalyst 13 to generate methane; the first methanation reaction is:

[0057] CO2+4H2→CH4+H2O;

[0058] Carbon monoxide and hydrogen undergo a second methanation reaction in the second chamber 6 under the action of the catalyst 13 to generate methane; the second methanation reaction is:

[0059] CO + 3H2 → CH4 + H2O;

[0060] In a closed system, coupling the first electrolysis reaction (water electrolysis), the second electrolysis reaction (carbon dioxide electrolysis) with the first methanation reaction and the second methanation reaction can break through the chemical equilibrium constraints of the first methanation reaction (carbon dioxide methanation reaction) alone, greatly improve the reaction efficiency and conversion rate of methanation, and increase the methane yield.

[0061] The generated mixed gas of methane and water vapor is output from the second output terminal 62. After separation and purification, the methane is transported to the storage device for storage, and the water vapor can also be circulated to provide input air flow to the first chamber 2. The gas circulation improves the overall conversion rate and further reduces the system energy consumption and cost.

[0062] In one preferred embodiment, the first electrolytic cell 3 is a proton conductor electrolytic cell;

[0063] The first electrolytic cell 3 includes a first anode layer 10 and a first cathode layer 11. The first anode layer 10 is adjacent to the first chamber 2, the first cathode layer 11 is adjacent to the second chamber 6, and a first electrolyte layer 9 is disposed between the first anode layer 10 and the first cathode layer 11; see Figure 2 When the first electrolysis reaction occurs, the first anode layer 10 adjacent to the first chamber 2 reacts: H2O→2H + +0.5O2+2e 2- The generated oxygen is discharged into the first chamber 2 adjacent to the first anode layer 10, and finally discharged from the first chamber 2 through the first output terminal 22. It is known to those skilled in the art that the electrolyte layer of the proton conductor electrolytic cell, i.e., the first electrolyte layer 9, has the ability to conduct protons, so the protons generated in the first anode layer 10 can be conducted to the first cathode layer 11 through the first electrolyte layer 9, and the first cathode layer 11 reacts: 2H + +2e2- →H2, the generated hydrogen is discharged into the second chamber 6 adjacent to the first cathode layer 11, a methanation reaction occurs in the second chamber 6, and the reaction product is discharged from the second chamber 6 through the second output end 62.

[0064] Preferably, in the proton conductor electrolytic cell, the material of the first cathode layer is selected from PbBa 0.5 Sr 0.5 Co 0.2 Fe 0.8 O 3-δ (PBSCF), La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) and Pr2Ni 0.6 Cu 0.4 O 4+δ (PNC), the material of the first anode layer is Ni-BaZr x Y 1-x O3(Ni-BZY),Ni-BaZr 1-x-y Ce y Y x O 3-δ (Ni-BZCY) and Ni-BaZr 1-x-y- z Ce z Y y Yb x O 3-δ (Ni-BZCYYb), the material of the first electrolyte layer is BaZr x Y 1-x O3(BZY),BaZr 1-x- y Ce y Y x O 3-δ (BZCY) and BaZr 1-x-y-z Ce z Y y Yb x O 3-δ One of (BZCYYb).

[0065] In one preferred embodiment, the second electrolytic cell 4 is an oxygen ion conductor electrolytic cell;

[0066] The second electrolytic cell 4 includes a second cathode layer 8 and a second anode layer 7, wherein the second anode layer 7 is adjacent to the first chamber 2, the second cathode layer 8 is adjacent to the second chamber 6, and a second electrolyte layer 9 is disposed between the second anode layer 7 and the second cathode layer 8; see also Figure 2When the second electrolysis reaction occurs, the second cathode layer 8 adjacent to the second chamber 6 reacts: CO2+2e 2- →CO+O 2- The generated carbon monoxide is discharged into the second chamber 6 adjacent to the second cathode layer 8. Those skilled in the art will know that the electrolyte layer of the oxygen ion conductor electrolytic cell, i.e., the second electrolyte layer 9, has the ability to conduct oxygen ions. The oxygen ions are conducted to the second anode layer 7 through the second electrolyte layer 9, lose electrons to generate oxygen and are discharged into the first chamber 2 adjacent to the second anode layer 7, and are finally discharged from the first chamber 2 through the first output terminal 22.

[0067] Preferably, in the oxygen ion conductor electrolytic cell, the material of the second cathode layer is selected from La 1-x Sr x Fe1 -y Co y O3(LSCF), La 1-x Sr x MnO3 (LSM), the material of the second anode layer is Ni-YSZ, and the material of the second electrolyte layer is Ce 0.8 G 0.2 O 1.9 (GDC), Y 0.8 Zr 0.2 O3(YSZ), La 1-x Sr x Ga 1-y Mg y O 3-δ One of the (LSGM).

[0068] In one preferred embodiment, an insulating member 5 is disposed between the ends of the first electrolytic cell 3 and the second electrolytic cell 4 that are close to each other, so as to simplify the connection structure between the first electrolytic cell 3 and the second electrolytic cell 4 and make the structure of the mixed ion conductor electrolytic cell compact.

[0069] In one preferred embodiment, the mixed ion conductor electrolytic cell is tubular;

[0070] The first chamber 2 is arranged inside the mixed ion conductor electrolytic cell and the second chamber 6 is arranged outside, or the second chamber 6 is arranged inside the mixed ion conductor electrolytic cell and the first chamber 2 is arranged outside. The structure is simple, the layout is convenient, and it is beneficial to improve the reaction efficiency.

[0071] Preferably, a second chamber 6 is arranged inside the mixed ion conductor electrolytic cell and a first chamber 2 is arranged outside the second chamber 6. A second chamber 6 for the first methanation reaction and the second methanation reaction is arranged inside the tubular mixed ion conductor electrolytic cell, which is beneficial for the reaction gas to gather inside the tube and further improve the reaction efficiency and conversion rate.

[0072] In one preferred embodiment, the first electrolytic cell 3 and the second electrolytic cell 4 are arranged in sequence along the axial direction of the tubular mixed ion conductor electrolytic cell;

[0073] The first input end 21 is close to the first electrolytic cell 3 and far away from the second electrolytic cell 4, and the first output end 22 is far away from the first electrolytic cell 3 and close to the second electrolytic cell 4;

[0074] The second input end 61 is far away from the first electrolytic cell 3 and close to the second electrolytic cell 4 , and the second output end 62 is close to the first electrolytic cell 3 and far away from the second electrolytic cell 4 .

[0075] After water vapor enters the first chamber 2 from the first input end 21, it undergoes a first electrolysis reaction in the first electrolytic cell 3 to generate hydrogen, which is discharged into the second chamber 6. The discharge position is close to the second output end 62 and away from the second input end 61, providing a hydrogen atmosphere for the methanation reaction; carbon dioxide enters the second chamber 6 from the second input end 61, and part of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell 4 to generate carbon monoxide. The mixed gas flow of carbon dioxide and carbon monoxide undergoes a methanation reaction through the hydrogen atmosphere, which facilitates the reaction;

[0076] Preferably, the first electrolytic cell 3 is a proton conductor electrolytic cell and the second electrolytic cell 4 is an oxygen ion conductor electrolytic cell. It is known to those skilled in the art that the oxygen ion conductor electrolytic cell is a high-temperature electrolytic cell with an operating temperature of 600-800°C. Electrolyzing carbon dioxide in the high-temperature section can improve the efficiency of carbon dioxide electrolysis, so that the proportion of carbon monoxide in the reaction gas increases. The increase in the proportion of carbon monoxide can simplify the reaction path, reduce the total energy demand of the entire reaction, and improve the reaction efficiency. The proton conductor electrolytic cell is a medium-low temperature electrolytic cell with an operating temperature of 300-600°C. Water is electrolyzed in the medium-low temperature section and a methanation reaction occurs. The methanation reaction is an exothermic reaction. The medium-low temperature is conducive to promoting the methanation reaction to proceed in the forward direction and improving the methane yield. At the same time, the water electrolysis reaction absorbs the heat released by the methanation reaction, so that the heat energy is efficiently utilized and energy consumption is reduced. Preferably, the insulating member 5 is a high-temperature resistant insulating member, which can realize the division of the high temperature zone and the medium-low temperature zone.

[0077] Furthermore, the carbon dioxide is pressurized and input into the second chamber 6. The second chamber 6 is a reaction chamber for the methanation reaction. The methanation reaction is a reaction in which the amount of gaseous substance decreases. Pressurizing the second chamber 6 can increase the pressure in the second chamber 6, so that the equilibrium moves in a positive direction, thereby promoting the methanation reaction to proceed in a positive direction and increasing the methane yield.

[0078] In one preferred embodiment, the first chamber 2 and the second chamber 6 are separated by a mixed ion conductor electrolytic cell, which simplifies the device structure and further improves the compactness of the device.

[0079] Further, see Figure 1-2The mixed ion conductor electrolytic cell is arranged in a housing 1 with an inner cavity, and the mixed ion conductor electrolytic cell divides the inner cavity into a first chamber 2 and a second chamber 6, has a simple structure, a compact layout, and has high practicality and economy;

[0080] Preferably, the mixed ion conductor electrolytic cell is tubular and has a circular cross-section. The side wall of the shell 1 is cylindrical, which is coaxially arranged with the tubular mixed ion conductor electrolytic cell. The top wall and bottom wall of the cylinder are penetrated at both axial ends of the mixed ion conductor electrolytic cell, and the top wall and bottom wall of the cylinder are respectively sealed and connected to the mixed ion conductor electrolytic cell, dividing the inner cavity of the shell 1 into a first chamber 2 and a second chamber 6. The first chamber 2 is located outside the tubular mixed ion conductor electrolytic cell, and the second chamber 6 is located inside the tubular mixed ion conductor electrolytic cell. The top of the side wall of the shell 1 is provided with a first input end 21, and the bottom of the side wall is provided with a first output end 22. The bottom end of the mixed ion conductor electrolytic cell is the second input end 61, and the top end of the mixed ion conductor electrolytic cell is the second output end 62, which further simplifies and optimizes the device structure and makes the overall layout more compact.

[0081] A method for synthesizing methane, using a mixed ion conductor solid oxide electrolytic cell methane synthesis device, comprises the following steps:

[0082] Step 1: remove impurities in the second chamber 6, purge the second chamber 6 with an appropriate amount of safety gas such as nitrogen, remove residual gas or waste gas in the second chamber 6, and input gas into the second chamber 6 through the second input end 61 for purging, and then heat the mixed ion conductor electrolytic cell to the working temperature; when the first electrolytic cell 3 is a proton conductor electrolytic cell and the second electrolytic cell 4 is an oxygen ion conductor electrolytic cell, heat the two sections separately, wherein the first electrolytic cell 3 is heated to a working temperature of 300-600°C, and the second electrolytic cell 4 is heated to a working temperature of 600-800°C;

[0083] Step 2: After the temperature is raised, carbon dioxide is input into the second chamber 6 from the second input end 61, and water vapor is input into the first chamber 2 from the first input end 21, and the water vapor passes through the first chamber 2 at normal pressure; if gas is input into the second chamber 6 through the second input end 61 during purging, the input gas is switched to carbon dioxide, preferably, carbon dioxide is input under pressure to promote the methanation reaction to proceed in the positive direction of reducing the amount of gaseous substances, thereby increasing the methane yield;

[0084] Step 3: The mixed ion conductor electrolytic cell is connected to an external power supply, and the water vapor undergoes a first electrolytic reaction in the first electrolytic cell 3 to generate hydrogen, and the hydrogen is discharged into the second chamber 6; part of the carbon dioxide undergoes a second electrolytic reaction in the second electrolytic cell 4 to generate carbon monoxide, and the carbon monoxide is discharged into the second chamber 6;

[0085] When the first electrolysis reaction occurs, the first anode layer 10 adjacent to the first chamber 2 reacts: H2O→2H + +0.5O2+2e 2- The generated oxygen is desorbed and discharged into the first chamber 2 adjacent to the first anode layer 10, and finally discharged from the first chamber 2 through the first output terminal 22. The electrolyte layer of the proton conductor electrolytic cell, i.e., the first electrolyte layer 9, has the ability to conduct protons. Therefore, the protons generated in the first anode layer 10 can be conducted to the first cathode layer 11 through the first electrolyte layer 9, and the first cathode layer 11 reacts: 2H + +2e 2- →H2, the generated hydrogen is desorbed and discharged into the second chamber 6 adjacent to the first cathode layer 11;

[0086] When the second electrolysis reaction occurs, the second cathode layer 8 adjacent to the second chamber 6 reacts: CO2+2e 2- →CO+O 2- , the generated carbon monoxide is desorbed and discharged into the second chamber 6 adjacent to the second cathode layer 8, the electrolyte layer of the oxygen ion conductor electrolytic cell, i.e., the second electrolyte layer 9, has the ability to conduct oxygen ions, and the oxygen ions are conducted to the second anode layer 7 through the second electrolyte layer 9, lose electrons to generate oxygen, and are desorbed and discharged into the first chamber 2 adjacent to the second anode layer 7, and finally discharged from the first chamber 2 through the first output terminal 22;

[0087] Step 4: Another portion of carbon dioxide and hydrogen undergo a first methanation reaction in the second chamber 6 under the action of the catalyst 13 to generate methane, and carbon monoxide and hydrogen undergo a second methanation reaction in the second chamber 6 under the action of the catalyst 13 to generate methane;

[0088] The other part of carbon dioxide that has not undergone the second electrolysis reaction undergoes a first methanation reaction with hydrogen in the second chamber 6 under the action of the catalyst 13 to generate methane: CO2+4H2→CH4+H2O; the carbon monoxide and hydrogen desorbed from the second cathode layer 8 and discharged into the second chamber 6 undergo a second methanation reaction with hydrogen in the second chamber 6 under the action of the catalyst 13 to generate methane: CO+3H2→CH4+H2O;

[0089] Step 5: The methane generated by the second methanation reaction from the first methanation reaction is discharged from the second chamber 6 from the second output end 62. After separation and purification, the methane is transported to a storage device for storage. The water vapor can also be circulated to provide an input airflow to the first chamber 2.

[0090] The system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art may understand and implement it without creative work.

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A mixed ion conductor solid oxide electrolytic cell methane synthesis device, characterized in that: The invention comprises a mixed ion conductor electrolytic cell, a first chamber located at one side of the mixed ion conductor electrolytic cell, and a second chamber located at the other side of the mixed ion conductor electrolytic cell, wherein the first chamber is isolated from the second chamber; The mixed ion conductor electrolytic cell comprises a first electrolytic cell and a second electrolytic cell; The first chamber includes a first input end and a first output end; The second chamber comprises a second input end and a second output end; a catalyst is arranged in the second chamber; Water vapor enters the first chamber from the first input end, the water vapor undergoes a first electrolysis reaction in the first electrolytic cell to generate hydrogen, and the hydrogen is discharged into the second chamber; Carbon dioxide enters the second chamber from the second input end, part of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell to generate carbon monoxide, and the carbon monoxide is discharged into the second chamber; The other part of the carbon dioxide that has not undergone the second electrolysis reaction undergoes a first methanation reaction with the hydrogen in the second chamber under the action of the catalyst to generate methane; The carbon monoxide and the hydrogen undergo a second methanation reaction in the second chamber under the action of the catalyst to generate methane; The first electrolytic cell is a proton conductor electrolytic cell; The first electrolytic cell comprises a first cathode layer and a first anode layer, the first anode layer is adjacent to the first chamber, and the first cathode layer is adjacent to the second chamber; The second electrolytic cell is an oxygen ion conductor electrolytic cell; The second electrolytic cell comprises a second cathode layer and a second anode layer, the second anode layer is adjacent to the first chamber, and the second cathode layer is adjacent to the second chamber; The ends of the first electrolytic cell and the second electrolytic cell close to each other are connected via an insulating member; The second input end is far away from the first electrolytic cell and close to the second electrolytic cell, and the second output end is close to the first electrolytic cell and far away from the second electrolytic cell; The first input end is close to the first electrolytic cell and far away from the second electrolytic cell, and the first output end is far away from the first electrolytic cell and close to the second electrolytic cell.

2. The mixed ion conductor solid oxide electrolytic cell methane synthesis device according to claim 1, characterized in that: The mixed ion conductor electrolytic cell is in a tubular form; The first chamber is arranged inside the mixed ion conductor electrolytic cell and the second chamber is arranged outside the mixed ion conductor electrolytic cell, or the first chamber is arranged inside the mixed ion conductor electrolytic cell and the second chamber is arranged outside the mixed ion conductor electrolytic cell.

3. The mixed ion conductor solid oxide electrolytic cell methane synthesis device according to claim 2, characterized in that: The first electrolytic cell and the second electrolytic cell are arranged sequentially along the axial direction of the tubular mixed ion conductor electrolytic cell.

4. The mixed ion conductor solid oxide electrolytic cell methane synthesis device according to claim 1, characterized in that: The carbon dioxide is pressurized and input into the second chamber.

5. The mixed ion conductor solid oxide electrolytic cell methane synthesis device according to claim 1, characterized in that: The first chamber is separated from the second chamber by the mixed ion conductor electrolytic cell.

6. The mixed ion conductor solid oxide electrolytic cell methane synthesis device according to claim 1, characterized in that: The mixed ion conductor electrolytic cell is disposed in a housing with an inner cavity, and the mixed ion conductor electrolytic cell divides the inner cavity into the first chamber and the second chamber.

7. A method for synthesizing methane, using the mixed ion conductor solid oxide electrolytic cell methane synthesis device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: removing impurities in the second chamber and heating the mixed ion conductor electrolytic cell to a working temperature; Step 2: inputting the carbon dioxide into the second chamber from the second input end, and inputting the water vapor into the first chamber from the first input end; Step 3: The water vapor undergoes a first electrolysis reaction in the first electrolytic cell to generate the hydrogen, and the hydrogen is discharged into the second chamber; a portion of the carbon dioxide undergoes a second electrolysis reaction in the second electrolytic cell to generate the carbon monoxide, and the carbon monoxide is discharged into the second chamber; Step 4: Another portion of the carbon dioxide and the hydrogen undergo a first methanation reaction in the second chamber under the action of the catalyst to generate methane, and the carbon monoxide and the hydrogen undergo a second methanation reaction in the second chamber under the action of the catalyst to generate methane; the carbon monoxide promotes the first methanation reaction; and the carbon dioxide promotes the second methanation reaction; Step 5: The methane is discharged from the second chamber through the second output end.

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