Electrolytic cell unit, electrolytic cell device and hydrocarbon production system, method of making and using an electrolytic cell unit

Abstract

The present application obtains an electrolytic cell unit (U) that can efficiently perform electrolysis of water and carbon dioxide. The electrolytic cell unit (U) is configured to at least include: an electrolytic cell (1) in which an electrolyte layer (1a) is formed with an electrode layer (2) and a counter electrode layer (3), and an exhaust passage (5a) that exhausts hydrogen generated in the electrode layer (2), wherein the electrolytic cell (1) is formed in a thin layer shape on a support body (4), and in at least a part of the exhaust passage (5a), a reverse water gas shift reaction portion (20) that generates carbon monoxide by using carbon dioxide and the above hydrogen through a reverse water gas shift reaction is provided.

Description

Technical Field

[0001] This invention relates to an electrolytic cell unit having an electrolytic cell, a method for preparing or using the electrolytic cell, an electrolytic cell apparatus having the electrolytic cell unit, and a hydrocarbon preparation system having such an electrolytic cell apparatus, wherein the electrolytic cell is configured to have an electrode layer and a counter electrode layer sandwiched between an electrolyte layer.

[0002] This hydrocarbon preparation system is configured to produce hydrocarbons from at least water and carbon monoxide, and the electrolytic cell device, which has an electrolytic cell unit, is used for the electrolysis of a hydrogen source (typically water) and the electrolysis of a carbon monoxide source (typically carbon dioxide). Background Technology

[0003] Such a hydrocarbon preparation system is disclosed in patent document 1 or 2.

[0004] The system disclosed in Patent Document 1 includes a high-temperature electrolyte (HTE) reactor (equivalent to the electrolysis reaction section of the present invention), which includes a stack of electrolysis cells (equivalent to the electrolysis cell unit of the present invention) that generate hydrogen from water vapor and carbon dioxide or synthesis feed gas (representing "synthesis gas" as a mixture of hydrogen and carbon monoxide). The system converts the synthesis gas obtained in the electrolysis cell into a desired combustible gas through heterogeneous catalysis.

[0005] Therefore, the technology disclosed in Patent Document 1 sets up a hydrocarbon synthesis section on the downstream side of the electrolysis reaction section to prepare hydrocarbons using water and carbon dioxide as starting materials.

[0006] Referring to Patent Document 1 Figure 3 The system is a large, cylindrical device.

[0007] On the other hand, the technology disclosed in Patent Document 2 relates to a power-to-gas unit that generates a useful gas (specifically methane) from electricity, and specifically discloses a technology that contains a methanation reaction catalyst material in the cathode of a stack of solid oxide (SOEC) basic electrolytic cells.

[0008] In the technology disclosed in Patent Document 2, the electrolytic cell is also called the electrolytic reaction section, and the methanation reaction catalyst material set at the cathode constitutes the hydrocarbon synthesis section.

[0009] In these existing technologies, a so-called "co-electrolysis" is carried out in the electrolysis reaction section, where water and carbon dioxide are electrolyzed together. Heterogeneous catalysts are used in the synthesis of hydrocarbons (so-called methanation).

[0010] Existing technical documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Publication No. 2016-522166,

[0013] Patent Document 2: Japanese Patent Application Publication No. 2019-112717. Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] However, the inventors have discovered the following problems regarding co-electrolysis in the electrolysis reaction section and hydrocarbon synthesis in the hydrocarbon synthesis section.

[0016] 1. Problems with co-electrolysis

[0017] Since the electrolysis voltage of water is approximately 1.23V, while that of carbon dioxide is approximately 1.33V, the electrolysis of carbon dioxide is much less efficient than that of water. Consequently, even if a co-electrolysis reaction were to occur, it would be difficult for carbon dioxide to be electrolyzed, making it impossible to adequately ensure the carbon monoxide concentration required for hydrocarbon synthesis.

[0018] 2. Problems in hydrocarbon synthesis

[0019] Although heterogeneous catalysts are reportedly used, the selection of such catalysts is difficult, and a technology for the stable synthesis of hydrocarbons has not yet been established.

[0020] 3. Furthermore, if we refer to the apparatus described in Patent Document 1, the apparatus is a large-scale apparatus, and there is room for improvement in terms of efficiently carrying out hydrocarbon synthesis without consuming special energy.

[0021] In view of this reality, the main objective of the present invention is to obtain a hydrocarbon preparation system in which, for example, hydrogen and carbon monoxide required for hydrocarbon synthesis can be adequately ensured in an electrolytic cell unit where the gas serves as a hydrogen or carbon monoxide source, and hydrocarbons can be prepared using the hydrogen and carbon monoxide thus generated.

[0022] Methods for solving problems

[0023] The first characteristic structure of the electrolytic cell unit involved in this invention is that,

[0024] The electrolytic cell unit is configured to include at least: an electrolytic cell with an electrode layer and a counter electrode layer sandwiched between an electrolyte layer, and a discharge passage for discharging hydrogen generated in the electrode layer.

[0025] The electrolytic cell is formed as a thin layer on the support, and at least a portion of the discharge passage is provided with a reverse water-gas shift reaction section that uses carbon dioxide and hydrogen to generate carbon monoxide via a reverse water-gas shift reaction.

[0026] This electrolytic cell unit includes an electrolytic cell through which hydrogen is generated from a gas that serves as a hydrogen source through an electrolytic reaction by flowing an electric current between the electrode layer and the counter electrode layer. The generated hydrogen is released into a discharge passage. By using at least a portion of this section as a reverse water-gas shift reaction section, carbon monoxide can be generated using carbon dioxide flowing through the discharge passage and the hydrogen generated in the electrode layer. Since the functional sections for the electrolytic reaction section and the reverse water-gas shift reaction section are configured as different sections (the former being the electrolytic cell and the latter the discharge passage), by using optimal materials in each section and maintaining a suitable temperature environment, carbon dioxide that cannot be fully decomposed in the electrolytic reaction section can be converted into carbon monoxide in the reverse water-gas shift reaction section. Furthermore, such electrolytic and reverse water-gas shift reactions can be carried out within a single electrolytic cell unit. As described below, since both reactions require high temperatures, it is preferable to house them in a single unit beforehand.

[0027] Furthermore, the electrolytic cell of this invention, by being formed into a thin film on the support, not only possesses a robust structure but also efficiently performs its full potential. In this respect, by making the electrolytic cell thin-film, a high-performance electrolytic cell can be achieved by suppressing the internal resistance of the cell, while simultaneously reducing the amount of expensive cell materials used, thus lowering the cost of the electrolytic cell.

[0028] The second structural feature of the present invention is that the support is metal.

[0029] By using metal as a support, strength is ensured with inexpensive metal materials, thereby suppressing material costs. Due to its higher machinability than ceramics, it offers greater shape selectivity.

[0030] The third structural feature of the present invention is that,

[0031] Multiple through holes are provided through the support body. The electrode layer is provided on one side of the support body, and the discharge passage is provided along the other side. At least a portion of the inner surface of the discharge passage is provided with the reverse water gas conversion reaction section.

[0032] According to this structural feature, an electrode layer is provided on one side of the support to generate hydrogen. The generated hydrogen is introduced from the electrode layer through multiple through holes into the discharge passage, so that the reaction in at least a portion of the reverse water-gas shift reaction section located in this part can occur well, and at least carbon monoxide can be generated when carbon dioxide is supplied.

[0033] The fourth structural feature of the present invention is that,

[0034] The reverse water gas conversion reaction section is provided in at least a portion of the interior of the through hole.

[0035] According to this feature structure, at least a portion of the through hole also functions as a reverse water-gas shift reaction section.

[0036] The fifth structural feature of the present invention is that,

[0037] The reverse water gas shift reaction section is provided on the side of the support that is different from the side where the electrolytic cell is formed.

[0038] According to this feature structure, the function of a reverse water-gas shift reaction section can be obtained on different sides of the support (e.g., the side opposite to the back side relative to the side where the electrolytic cell is formed).

[0039] The sixth structural feature of the present invention is that,

[0040] The device includes a separator that separates hydrogen generated in the electrode layer from oxygen generated in the counter electrode layer, and the reverse water gas shift reaction unit is provided on at least a portion of the hydrogen discharge passage side of the separator.

[0041] According to this feature structure, when an electrolytic reaction occurs in the electrolytic cell, hydrogen is generated from the electrode layer and oxygen is generated from the counter electrode layer. By pre-setting a partition, hydrogen and accompanying carbon dioxide can be used to carry out a reverse water-gas shift reaction in the reverse water-gas shift reaction section.

[0042] The seventh structural feature of the present invention is that the partition is made of metal.

[0043] By using metal as a separator, gas separation can be ensured with inexpensive metal materials, thereby reducing material costs. Furthermore, it is more easily processed than ceramics and offers a wider range of shape options.

[0044] The eighth structural feature of the present invention is that,

[0045] The reverse water gas shift reaction unit contains a reverse water gas shift catalyst that is a catalyst with metal or metal oxide supported on a carrier.

[0046] Based on this characteristic structure, a reverse water-gas shift reaction can be carried out by a catalyst supported on a support containing a metal or metal oxide.

[0047] The ninth structural feature of the present invention is that,

[0048] The reverse water gas shift reaction unit contains a reverse water gas shift catalyst that contains at least one of platinum, nickel, and iron.

[0049] Based on this characteristic structure, as described below, highly active reverse water-gas shift performance can be obtained.

[0050] The tenth structural feature of the present invention is that,

[0051] The carrier is a carrier whose main components are cerium oxide-based metal oxides or zirconium oxide-based metal oxides.

[0052] Based on this characteristic structure, as described below, while achieving high-activity reverse water-gas shift reaction performance, its catalytic ability and durability can be obtained in the high-temperature environment required for the reverse water-gas shift reaction. Furthermore, if the aforementioned support is primarily composed of cerium oxide-based or zirconium oxide-based metal oxides, its coefficient of thermal expansion can be made close to that of the materials used in the constituent materials or support structure of the electrolytic cell. Therefore, even under repeated low-temperature and high-temperature cycling, the electrolytic cell unit is not easily damaged, resulting in an electrolytic cell unit with excellent reliability and durability.

[0053] When a reverse water gas shift catalyst is obtained, it is preferable to have at least a firing process that is carried out at a temperature of 450°C or higher.

[0054] In the use of reverse water-gas shift catalysts, a high temperature range is required for the target reverse water-gas shift reaction to occur. Catalysts obtained by firing in this temperature range can be used stably. Preferably, the temperature is 450°C or higher; setting it to 600°C or higher, or 800°C or higher, improves stability in the high-temperature range and is therefore more preferable. For example, the catalyst can be used stably even when combined with a solid oxide electrolyzer used in a high-temperature range (e.g., 600°C to 800°C). However, if the firing temperature is too high, the cost of the firing process becomes excessive; therefore, its upper limit is around 1200°C.

[0055] When using a reverse-flow gas shift catalyst, it is preferable to use the reverse-flow gas shift catalyst in the reaction after the reduction pretreatment.

[0056] In the reverse water gas shift catalyst, at least some of the catalytic active components are often formed into metal oxides during the calcination process. By performing a reduction pretreatment (a reduction treatment before use), the oxidized catalytic active components can be reduced to exert their catalytic activity effectively.

[0057] The electrolytic cell device involved in this invention is characterized by the following structure:

[0058] It shall include at least: the electrolytic cell unit described above, an electrolytic raw material supply unit that supplies water or water and carbon dioxide to the electrolytic cell unit, and an electric power supply unit that supplies electricity.

[0059] According to this feature structure, while supplying electrolytic raw materials from the electrolytic raw material supply unit to the electrolytic cell unit, power is supplied from the power supply unit to the electrolytic cell, and the electrolytic raw materials can be electrolyzed using this power.

[0060] Here, for example, when the electrolytic feedstock is water, hydrogen can be generated through its electrolysis; when the electrolytic feedstock is carbon dioxide, carbon monoxide can be generated through its electrolysis. Furthermore, in the electrolytic cell unit of the present invention, since a reverse water-gas shift reaction section is provided in at least a portion of the discharge passage for generating carbon monoxide using carbon dioxide and the aforementioned hydrogen through a reverse water-gas shift reaction, carbon monoxide can also be generated through the reaction in that section.

[0061] The characteristic structure of the hydrocarbon preparation system involved in this invention is that,

[0062] It includes: the electrolytic cell unit or electrolytic cell apparatus described above, and at least a hydrocarbon synthesis reaction unit that reacts the hydrogen and the carbon monoxide to produce hydrocarbons.

[0063] According to this feature structure, using the electrolytic cell apparatus described above, hydrogen and carbon monoxide are supplied from the apparatus, thereby enabling the synthesis of hydrocarbons in the hydrocarbon synthesis reaction section. Here, since the electrolytic cell unit or apparatus according to the present invention at least includes a reverse water-gas shift reaction section, the carbon monoxide that is sometimes insufficient in the electrolysis of the electrolytic reaction section can be supplemented by this reverse water-gas shift reaction section, thus forming a compact and high-performance hydrocarbon preparation system.

[0064] The characteristic structure of the method for preparing the electrolytic cell unit involved in this invention is that,

[0065] In the formation process of the reverse water-gas conversion reaction section of the electrolytic cell unit, there is at least a firing process that is carried out at a temperature of 450°C or higher.

[0066] The electrolytic cell unit according to the present invention comprises an electrolytic cell having an electrode layer, an electrolyte layer, and a counter electrode layer, and a reverse water-gas shift reaction section. Both the formation of the electrolytic cell and the formation of the reverse water-gas shift reaction section require a firing operation, and the firing processes required for both sections can be performed simultaneously. Furthermore, for the reverse water-gas shift reaction section of the electrolytic cell unit operating in a higher temperature range, if a firing process is included at a temperature of 450°C or higher, the catalyst can be used stably, which is therefore preferable. More preferably, the firing temperature is set to 600°C or higher, and even more preferably, to 800°C or higher. With such a firing temperature, for example, even in the case of a reverse water-gas shift reaction section of a solid oxide type electrolytic cell unit operating in a temperature range of approximately 600°C to 800°C, the electrolytic cell and the reverse water-gas shift reaction section can function stably for a long time in such a high-temperature range. It should be noted that if the firing temperature is too high, the cost of the firing process becomes too high; therefore, its upper limit is approximately 1200°C.

[0067] The characteristic structure of the method of using the electrolytic cell unit involved in this invention is that,

[0068] The reverse water gas shift reaction unit is used after the reduction pretreatment is performed.

[0069] As described below, the active metal component of the catalyst suitable for the reverse water gas shift reaction section of the electrolytic cell unit involved in the present invention is an oxide in its state before use. By performing a reduction pretreatment before use, the activity as a reverse water gas shift catalyst can be improved. Attached Figure Description

[0070] [ Figure 1 [A diagram showing the structure of a hydrocarbon preparation system.]

[0071] [ Figure 2 [A schematic diagram showing the structure of the electrolysis reaction section.]

[0072] [ Figure 3 This diagram shows the structure of a system that integrates the electrolysis reaction section and the counter-current gas conversion reaction section.

[0073] [ Figure 4 A schematic diagram of an electrolytic cell unit equipped with an electrolysis reaction section and a reverse water-gas conversion reaction section.

[0074] [ Figure 5 A cross-sectional view of the electrolytic cell unit used in the comparative experiment where the gas supply passage on the electrode layer side is used as the reverse water-gas conversion reaction section.

[0075] [ Figure 6 [Structural diagram of a system with a heat exchange section between the electrolysis reaction section and the reverse water gas conversion reaction section.]

[0076] [ Figure 7 [ ] This diagram shows another structure of the hydrocarbon preparation system that introduces CO2 into the reverse water gas shift reaction section.

[0077] [ Figure 8 [Diagram showing another structure of a hydrocarbon preparation system with a hydrogen separation section.]

[0078] [ Figure 9 This diagram shows another structure of a hydrocarbon preparation system that includes a water separation section preceding the hydrocarbon synthesis reaction section.

[0079] [ Figure 10 This diagram shows another structure of a hydrocarbon preparation system that introduces only water into the electrolysis reaction section.

[0080] [ Figure 11 [ ] Schematic diagram representing the modulation state of the catalyst.

[0081] [ Figure 12 This diagram illustrates the coating, calcination, and pre-reduction treatment of the catalyst.

[0082] [ Figure 13 A schematic diagram of an electrolytic cell unit comprising an electrolysis reaction section, a reverse water-gas shift reaction section, and a hydrocarbon synthesis reaction section. Detailed Implementation

[0083] The embodiments of the present invention will be described with reference to the accompanying drawings.

[0084] Figure 1 This describes the structure of one method of the hydrocarbon preparation system 100 proposed by the inventor.

[0085] As shown in the figure, the hydrocarbon preparation system 100 sequentially includes an electrolysis reaction section 10, a first catalytic reaction section 20, a second catalytic reaction section 30, and a heavy hydrocarbon separation section 35 (shown as C in the figure). n H m It is composed of a separation section, a water separation section 40 (shown as an H2O separation section) and a carbon dioxide separation section 50 (shown as a CO2 separation section).

[0086] The electrolysis reaction section 10 described above is a site for electrolyzing at least a portion of the incoming gas. The first catalytic reaction section 20 described above is a reverse water-gas shift reaction section that causes at least a portion of the incoming gas to undergo a reverse water-gas shift reaction. The second catalytic reaction section 30 described above is configured to function as a hydrocarbon synthesis reaction section that synthesizes at least a portion of the incoming gas into hydrocarbons. Here, the synthesized hydrocarbons are mainly CH4 (hydrocarbons with 1 carbon atom), and also include lower saturated hydrocarbons with 2 to 4 carbon atoms. Furthermore, as shown below, by appropriately selecting the catalyst used in the second catalytic reaction section 30, heavier hydrocarbons with a higher carbon atom than the aforementioned lower saturated hydrocarbons, unsaturated hydrocarbons, or oxygen-containing hydrocarbons can also be synthesized. Therefore, in this specification, "hydrocarbon" is a concept that includes all of these, and is also collectively referred to as hydrocarbons.

[0087] The heavy hydrocarbon separation section 35, the water separation section 40, and the carbon dioxide separation section 50 remove specified components (in the order listed) from the gas flowing inside. n H m At least a portion of (H2O and CO2). Figure 1 As shown, the components removed and recovered by the water separation unit 40 and the carbon dioxide separation unit 50 are returned to designated parts of the system for reuse via the water return passage 41 and the carbon dioxide return passage 51. The two return passages 41 and 51 are represented by H2O and CO2, respectively, which are returned through them.

[0088] As a result, the hydrocarbon preparation system 100 essentially becomes a carbon-closed system that does not release CO2 outside the system.

[0089] In this diagram, the gas flowing into each part is shown in front of it, and the gas exiting from it is shown in the back.

[0090] In the electrolysis reaction section 10, H2O and CO2, which are the starting materials, flow in and are electrolyzed inside. While H2O is decomposed into H2 and O2, a portion of CO2 is decomposed into CO and O2 and released.

[0091] The reaction is as follows.

[0092] 2H₂O→2H₂+O₂ (Equation 1)

[0093] 2CO2→2CO+O2 (Equation 2)

[0094] These equations 1 and 2 are also... Figure 1 The electrolysis reaction section 10 is shown within the frame.

[0095] In the first catalytic reaction section 20 (reverse water-gas shift reaction section) mentioned above, H2 and CO2 flow in and undergo a reverse water-gas shift reaction inside, where CO2 becomes CO and H2 becomes H2O and is released.

[0096] The reaction is recorded as the following equilibrium reaction, but the reverse water-gas shift reaction is the reaction recorded in Equation 3 as proceeding to the right (the reaction proceeding in the direction of CO2 reacting with H2 to produce CO and H2O).

[0097] CO2 + H2 ⇔ CO + H2O (Equation 3)

[0098] Equation 3 is also... Figure 1 The first catalytic reaction section 20 (reverse water-gas shift reaction section) is shown within a box. The reverse water-gas shift catalyst cat1 used in the reaction is also schematically shown within the box.

[0099] In the second catalytic reaction section 30 (hydrocarbon synthesis reaction section) described above, H2 and CO flow in, and hydrocarbons are synthesized through a catalytic reaction. For example, the reaction of synthesizing CH4 from CO and H2 is described as the following equilibrium reaction, but the reaction of synthesizing CH4 from CO and H2 is a reaction that proceeds to the right side of the reaction described in the following formula 4 (a reaction that proceeds in the direction of the reaction of CO and H2 to produce CH4 and H2O).

[0100] CO + 3H₂ ⇔ CH₄ + H₂O (Equation 4)

[0101] Equation 4 is also... Figure 1 The second catalytic reaction section 30 (hydrocarbon synthesis reaction section) is shown in the box. The hydrocarbon synthesis catalyst cat2 used in the reaction is also schematically shown in the box.

[0102] In addition, the equilibrium reaction (Equation 3) also occurs in this region.

[0103] Furthermore, since the type of catalyst used in the second catalytic reaction section 30 can carry out FT (Fischer-Tropsch) synthesis reactions, etc., various hydrocarbons such as ethane, propane, butane, pentane, hexane, paraffin, and alkenes can be synthesized from CO and H2.

[0104] As described below, the inventors have shown an example of a catalyst using ruthenium as its catalytically active component, cat2, which is configured in the second catalytic reaction section 30. Heavy hydrocarbons can also be synthesized using catalysts containing iron or cobalt as their catalytically active components. These heavy hydrocarbons condense as the temperature decreases and can be separated from the transport gas. Therefore, in the heavy hydrocarbon separation section 35, the hydrocarbon components thus separated are separated.

[0105] The generated H2O is separated in the water separation section 40 and returned to the upstream side of the electrolysis reaction section 10 through the water return passage 41 (water recirculation line).

[0106] The generated CO2 is separated in the carbon dioxide separation section 50 and returned to the upstream side of the electrolysis reaction section 10 through the carbon dioxide return passage 51 (carbon dioxide recirculation line).

[0107] As a result, in this hydrocarbon preparation system 100, the final synthesized hydrocarbons can be supplied to the outside.

[0108] The above is a summary of the hydrocarbon preparation system 100. The structure and function of each part are explained below.

[0109] [Electrolysis Reaction Section]

[0110] As shown above, the electrolysis reaction unit 10 consumes the supplied electricity to decompose the incoming H2O and CO2 according to the above formulas 1 and 2.

[0111] exist Figure 2 The cross-sectional structure of the electrolysis reaction section 10 is schematically shown in the figure.

[0112] This figure shows an electrolytic cell unit U formed by stacking multiple layers to form an electrolytic stack (illustration omitted). The electrolytic cell unit U includes an electrolytic cell 1, which has an electrode layer 2 on one side of an electrolyte layer 1a and a counter electrode layer 3 on the other side. The electrode layer 2 serves as the cathode in the electrolytic cell 1, and the counter electrode layer 3 serves as the anode. Incidentally, the electrolytic cell unit U is supported by a metal support 4. It should be noted that, here, a solid oxide type electrolytic cell is used as an example of the electrolytic cell 1.

[0113] The electrolyte layer 1a described above can be formed in the form of a thin film with a thickness of 10 μm or less. As its constituent materials, YSZ (yttrium-stabilized zirconium oxide), SSZ (scandium oxide-stabilized zirconium oxide), GDC (gadolinium-doped cerium oxide), YDC (yttrium-doped cerium oxide), SDC (samarium-doped cerium oxide), LSGM (lanthanum gallate with added strontium magnesium), etc., can be used. Zirconia-based ceramics are particularly preferred.

[0114] The electrolyte layer 1a is preferably formed by a low-temperature firing method (e.g., a wet method that uses a low-temperature firing process instead of firing in a high-temperature region exceeding 1100°C), a spraying method (e.g., melt spraying, aerosol deposition, aerosol vapor deposition, powder spraying deposition, particle spraying deposition, cold spraying, etc.), a PVD method (sputtering, pulsed laser deposition, etc.), or a CVD method. These film-forming processes, which can be used in a low-temperature region, allow for the formation of a dense electrolyte layer 1a with high gas tightness and gas barrier properties without the need for firing in a high-temperature region exceeding 1100°C. Therefore, damage to the metal support 4 can be suppressed, and interdiffusion of elements between the metal support 4 and the electrode layer 2 can be suppressed, resulting in an electrolytic cell unit U with excellent performance and durability. In particular, low-cost components can be achieved by using methods such as low-temperature firing or spraying, which is therefore preferred. Furthermore, if a spraying method is used, a dense electrolyte layer 1a with high gas tightness and gas barrier properties can be easily obtained in a low-temperature region, which is even more preferred.

[0115] Furthermore, to shield against air leakage and exhibit high ion conductivity, the electrolyte layer 1a is densely constructed. The density of the electrolyte layer 1a is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. When the electrolyte layer 1a is a uniform layer, its density is preferably 95% or more, more preferably 98% or more. Additionally, when the electrolyte layer 1a is constructed as multiple layers, at least a portion of it preferably contains a layer with a density of 98% or more (dense electrolyte layer), more preferably a layer with a density of 99% or more (dense electrolyte layer). This is because if such a dense electrolyte layer is included in a portion of the electrolyte layer 1a, even when the electrolyte layer 1a is constructed as multiple layers, a dense electrolyte layer 1a with high airtightness and gas barrier properties can be easily formed.

[0116] The electrode layer 2 can be thinly disposed on the surface of the metal support 4 in an area larger than the area where the holes 4a are formed. When made thin, its thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. Such a thickness reduces the amount of expensive electrode layer material used, thus lowering costs, while ensuring sufficient electrode performance. The area where the holes (through holes) 4a are formed is entirely covered by the electrode layer 2. That is, the holes 4a are formed inside the area of ​​the metal support 4 where the electrode layer 2 is formed. In other words, all the holes 4a face the electrode layer 2.

[0117] The electrode layer 2 can be composed of composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2. In these examples, GDC, YSZ, and CeO2 can be referred to as aggregates in the composite material. It should be noted that the electrode layer 2 is preferably formed by a low-temperature firing method (e.g., a wet method that uses a low-temperature firing process instead of a high-temperature firing process above 1100°C), a spraying method (e.g., melt spraying, aerosol deposition, aerosol vapor deposition, powder spraying deposition, particle spraying deposition, cold spraying, etc.), a PVD method (sputtering or pulsed laser deposition, etc.), or a CVD method. These processes, which can be used in low-temperature regions, allow for the avoidance of high-temperature firing processes above 1100°C, resulting in a high-quality electrode layer 2. Therefore, the metal support 4 is not damaged, and elemental interdiffusion between the metal support 4 and the electrode layer 2 is suppressed, leading to an electrochemical element with excellent durability, which is therefore preferred. Furthermore, if a low-temperature firing method is used, the processing of raw materials becomes easier, making it even more preferable.

[0118] The counter electrode layer 3 can be formed in a thin layer on the surface of the electrolyte layer 1a opposite to the electrode layer 2. When formed as a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. By achieving such a thickness, the cost can be reduced by decreasing the amount of expensive counter electrode layer material used, while ensuring sufficient electrode performance. As the material for the counter electrode layer 3, for example, composite oxides such as LSCF and LSM, cerium oxide-based oxides, and mixtures thereof can be used. Particularly preferred is that the counter electrode layer 3 contains a perovskite-type oxide containing two or more elements selected from La, Sr, Sm, Mn, Co, and Fe.

[0119] These electrolyte layer 1a, electrode layer 2 and counter electrode layer 3 are formed into a thin film as described below, which the inventors refer to as being formed into a thin layer.

[0120] As shown above, the electrolytic cell unit U is a metal support type, and a metal support 4 serves as the support for the electrode layer 2. A supply passage forming member 5, forming a U-shape, is provided on the opposite side of the electrode layer 2, which is held by the metal support 4, for forming a gas supply passage 5a on the electrode layer side. Furthermore, multiple holes 4a are provided on the metal support 4, penetrating both the surface and the back side. Gases (H2O and CO2) supplied through the electrode layer side gas supply passage 5a become the target of electrolysis and are supplied to the electrode layer 2 through the multiple holes 4a. Additionally, the generated gases (H2, CO) flow out from these holes 4a.

[0121] On the other hand, regarding the counter electrode layer 3 side, a supply passage forming member 6 is also provided for forming a counter electrode layer side gas supply passage 6a. As shown in the figure, the supply passage forming member 6 has multiple slots on the counter electrode layer 3 side, configured to supply a conveying gas g2 (e.g., air) to the counter electrode layer side gas supply passage 6a.

[0122] Furthermore, the metal support 4 serves as a support to support the electrode layer 2, electrolyte layer 1a, and counter electrode layer 3, thereby maintaining the overall strength of the electrolytic cell 1 and the electrolytic cell unit U. In this example, a plate-shaped metal support 4 is used as the metal support, but it can also be other shapes, such as box-shaped or cylindrical.

[0123] It should be noted that the metal support 4 only needs to have sufficient strength to form the electrolytic cell unit U. For example, a support with a thickness of about 0.1 mm to 2 mm, preferably about 0.1 mm to 1 mm, and more preferably about 0.1 mm to 0.5 mm can be used. In this embodiment, the support is metal, but it can also be ceramic, for example.

[0124] The metal support 4 has, for example, multiple holes 4a provided through the surface and back sides of the metal plate. For example, the holes 4a can be provided on the metal support 4 by mechanical, chemical, or optical perforation. The holes 4a function to allow gas to pass through the surface of the metal support 4 from the back side. The holes 4a can also be positioned relative to the gas's laminar flow direction (…). Figure 2 The paper is tilted (both the front and back sides are tilted).

[0125] By using a ferritic stainless steel material (an example of an Fe-Cr alloy) as the base material for the metal support 4, the coefficient of thermal expansion can be made close to that of materials such as YSZ (yttrium-stabilized zirconium oxide) or GDC (gadolinium-doped cerium oxide, also known as CGO), which are used as materials for the electrode layer 2 or electrolyte layer 1a. Therefore, the electrolytic cell unit U is less susceptible to damage even under repeated low-temperature and high-temperature cycling. This results in an electrolytic cell unit U with excellent long-term durability, which is therefore preferred.

[0126] The supply passage forming components 5 and 6 of the above-mentioned electrolytic cell unit U can be made of the same material as the metal support 4, and their thickness can also be basically the same.

[0127] The metal support 4 and the two supply passage forming components 5 and 6 are conductive and are constructed in an airtight manner, serving as partitions to separate the supply passages 5a and 6a.

[0128] Electrolytic cell unit U with the above structure receives power from the power supply unit (in) during electrolysis. Figure 2 (Represented by a battery) Direct current is supplied between a pair of electrode layers 2 and 3 that sandwich the electrolyte layer 1a. In this embodiment, as shown in the figure, the case where the electrode layer 2 side is negative and the counter electrode layer 3 side is positive is illustrated. It should be noted that, depending on the structure of the electrolytic cell unit U, sometimes the electrode layer 2 side is positive and the counter electrode layer 3 side is negative.

[0129] Then, by supplying raw materials from the electrolytic feedstock section ( Figure 1 In the electrolysis reaction section 10, upstream of the electrode layer 2, H2O and CO2, the gases to be electrolyzed, are supplied to the electrode layer 2, while a transport gas g2 is supplied to the counter electrode layer side. The reactions shown in Formulas 1 and 2 occur within the electrolysis cell 1, and the decomposed gases can be extracted. Here, the supply of H2O can be either water or water vapor, or both. Therefore, in this invention, at least an electrolysis cell unit U, an electrolysis raw material supply section that supplies water and / or water vapor and carbon dioxide to the electrolysis cell unit U, and an electricity supply section that supplies electricity are provided to construct an electrolysis cell apparatus.

[0130] exist Figure 2 In the diagram, the gases supplied (H2O, CO2) and released (H2O, H2, CO, O2, CO2) during the electrolysis reaction are listed on the top and bottom of the electrolytic cell unit U. This is for ease of understanding. In reality, the gas supply passage 5a on the electrode layer side and the gas supply passage 6a on the counter electrode layer side are... Figure 2 It is formed by extending in the direction of the paper's surface and back side, for example, in Figure 2 The gas (H2O, CO2) recorded on the upper supply side of the electrolytic cell unit U can be recovered from the paper surface side, and the gas (H2O, H2, CO, O2, CO2) recorded on the lower discharge side of the electrolytic cell 1 can be recovered from the paper back side (see below). Figure 4 It should be noted that, in order to facilitate the discharge of O2 generated in the electrolysis reaction, a transport gas g2, such as air, can be allowed to flow into the electrolysis cell unit U.

[0131] When H2O and CO2 are supplied to the electrolysis reaction section 10 for electrolysis, H2O is more easily electrolyzed because its electrolysis voltage is lower than that of CO2. Therefore, if equal amounts of H2O and CO2 are supplied to the electrolysis reaction section 10 for electrolysis, the H2 concentration at the outlet of the electrolysis reaction section 10 is more likely to be higher than the CO concentration, and unreacted CO2 is more likely to remain.

[0132] [First Catalytic Reaction Section (Reverse Water-Gas Shift Reaction Section)]

[0133] As shown above, the first catalytic reaction section 20 (reverse water-gas shift reaction section) undergoes a reverse water-gas shift reaction, using supplied H2 to convert CO2 into CO, and H2 into H2O. That is, CO2 that was not decomposed and remained in the electrolysis reaction section 10 where H2O and CO2 are supplied for electrolysis is converted into CO.

[0134] The reaction here is shown in Equation 3. This reaction is endothermic and is an equilibrium reaction corresponding to the reaction temperature conditions. As a result, as described above, a catalyst that can cause the reaction represented by Equation 3 to occur at the highest possible temperature (e.g., 600°C to 800°C) is preferred.

[0135] When describing the catalysts in this specification, the component that has the activity of a catalyst is sometimes referred to as the "catalytically active component," and the support on which the catalytically active component is supported is referred to as the "support."

[0136] As described below, the inventors studied various combinations of catalytically active ingredients and supports and found that certain combinations are preferred.

[0137] This catalyst is prepared by impregnating a support in a solution containing the catalytically active component (metal), removing it, and then drying and heating it. This process readily yields a supported catalyst (impregnated support) with the catalytically active component distributed on the surface of the support. The heating treatment is a calcination process. For information on catalyst preparation and use, please refer to [reference needed]. Figure 11 , Figure 12 Please provide an explanation.

[0138] The modulation method described here applies to various combinations of catalytically active ingredients and supports, differing only in the starting materials; everything else remains the same. Figure 11 Examples of the reverse-flow gas shift catalyst cat1 and the hydrocarbon synthesis catalyst cat2 involved in this invention are also shown in the figure. In this figure, the catalytically active component of the reverse-flow gas shift catalyst cat1 is labeled as ca1, and its support is labeled as cb1. On the other hand, regarding the hydrocarbon synthesis catalyst cat2, its catalytically active component is labeled as ca2, and its support is labeled as cb2.

[0139] like Figure 11As shown, in the catalyst preparation process, an aqueous solution containing a metal component (metal catalyst) that becomes the catalytically active components Ca1 and Ca2 is obtained. Supports Cb1 and Cb2 are added to this aqueous solution, and the mixture is stirred and impregnated (a). Then, a drying-crushing-forming process (b) is performed, involving evaporation, drying, and then pulverization and molding. Finally, a firing process (c) is performed, where the resulting molded body is fired in air. This yields the target substances (Cat1 and Cat2). Therefore, this type of catalyst is also called an impregnated supported catalyst.

[0140] In this case, such as Figure 12 As shown in the example of the counter-current water-gas shift catalyst cat1, it can also be coated onto the part where the catalyst is used and then fired. Figure 12 (a) illustrates a coating-firing process in which a reverse water-gas shift catalyst cat1 is coated onto a perforated metal support 4 to form a coating layer 20a, followed by firing. Figure 12 (b) shows the pre-reduction treatment process before using the reverse water gas shift catalyst cat1, where H2 is flowed in for pre-reduction treatment.

[0141] It should be noted that if the firing process is carried out in air, some or all of the supported catalytically active components Ca1 and Ca2 will be oxidized. Performing a so-called reduction pretreatment before using the catalyst to reduce the oxidized catalytically active components can also significantly improve its activity. Figure 12 (b) shows the state in which a reducing gas (representatively H2) flows over the surface of the catalyst for reduction pretreatment.

[0142] (Catalyst used)

[0143] As the reverse water-gas shift catalyst cat1 used in the first catalytic reaction section 20, the inventors selected a catalyst that meets the following requirements.

[0144] A catalyst comprising at least one or two of platinum, nickel, and iron as catalytically active component Ca1, supported on a support Cb1 mainly composed of cerium oxide or zirconium oxide. Here, since the strength of the catalyst Cat1 can be improved, the proportion of the support Cb1 relative to the total catalyst is preferably 55% by weight or more, more preferably 60% by weight or more, and even more preferably 65% ​​by weight or more. Furthermore, the upper limit of this proportion can be, for example, 99.5% by weight, because if it is higher, the catalytically active component Ca1 cannot be sufficiently loaded, and sometimes it is difficult to obtain the desired effect as a reverse water-gas shift catalyst Cat1.

[0145] In addition, as a cerium oxide-based metal oxide, it can also be cerium oxide doped with at least one of gadolinium, samarium, and yttrium.

[0146] In addition, as a zirconium oxide-based metal oxide, it can also be a zirconium oxide stabilized by at least one of yttrium oxide and scandium oxide.

[0147] It should be noted that, since the reverse water-gas shift reaction can proceed well, the loading of the catalytically active component Ca1 is preferably 0.5% by weight or more, more preferably 1% by weight or more, and even more preferably 5% by weight or more. Furthermore, even if the loading of the catalytically active component Ca1 is excessively increased, it is difficult to achieve a highly dispersed loading of Ca1, which not only makes it difficult to significantly improve catalytic activity but also increases the catalyst cost. Therefore, the loading of the catalytically active component Ca1 is preferably 35% by weight or less, more preferably 30% by weight or less, and even more preferably 25% by weight or less.

[0148] In addition to platinum, nickel, and iron as the catalytically active component Ca1, copper is preferably supported as another catalytically active component Ca1. In this structure, the copper loading is the same as or lower than the Ca1 loading of any one or two of nickel and iron as the main catalytically active component Ca1.

[0149] The following describes the test results of an example in which various changes were made to the catalytic active component Ca1 and the support CB1, which is the reverse water gas shift catalyst cat1 used in the first catalytic reaction section 20.

[0150] As a catalytically active component, Ca1 was studied for Ni and Fe, and also for Pt (platinum).

[0151] The carriers cb1 were ZrO2 (zirconia), YSZ (yttrium-stabilized zirconia), GDC (gadolinium-doped cerium oxide), and CeO2 (cerium oxide) as examples, and Al2O3 (aluminum oxide) was also studied.

[0152] The following description introduces Experimental Example 1 and Experimental Example 2. The difference between the two experiments is that in the calcination of the reverse water gas shift catalyst cat1, Experimental Example 1 sets its calcination temperature to 450°C, while Experimental Example 2 sets its calcination temperature to the high-temperature side of 600°C to 1000°C.

[0153] (Experimental Example 1)

[0154] The test results of Examples (1 to 19) with various changes to the support when using the catalyst in the first catalytic reaction unit 20 are described.

[0155] Ni and Fe were studied as catalytically active components, as was Pt (platinum).

[0156] ZrO2 (zirconia), YSZ (yttrium-stabilized zirconia), GDC (gadolinium-doped cerium oxide), and CeO2 (cerium oxide) were used as supports in the examples, and Al2O3 (aluminum oxide) was also studied.

[0157] (Catalyst modulation)

[0158] When preparing the reverse water-gas shift catalyst cat1, an aqueous solution containing one or two of the following is obtained, based on the composition of the target catalyst: a quantitatively dissolved nickel compound (nickel nitrate, nickel chloride, nickel sulfate, nickel ammonium sulfate, nickel acetate, nickel oxalate, nickel citrate, etc.) and a water-soluble iron compound (ferric nitrate, ferric chloride, ferric sulfate, ferric ammonium sulfate, ferric acetate, ferric oxalate, ferric citrate, etc.). Similarly, when copper is loaded onto the catalyst as another catalytically active component, c1, an aqueous solution containing a quantitatively dissolved copper compound (copper nitrate, copper chloride, copper sulfate, copper ammonium sulfate, copper acetate, copper oxalate, copper citrate, etc.) is obtained. A specified amount of carrier powder (cerium oxide, zirconium oxide, GDC, YSZ, Al2O3) is added to this aqueous solution, stirred, impregnated, evaporated and dried, then pulverized, shaped, and fired in air. This impregnation is the "impregnation loading process" as described in this invention, and the product is the "impregnation loaded material".

[0159] It should be noted that the catalysts in the following examples were prepared using nickel nitrate hexahydrate, ferric nitrate nonahydrate, and copper nitrate trihydrate, respectively. Additionally, the catalyst using Pt was prepared using tetraammineplatinum hydroxide.

[0160] The evaporation, drying, or calcination temperatures in the preparation of the catalyst can be carried out within the commonly used temperature range. In Test Example 1, the catalysts in the following examples were set to 80°C, 80°C, and 450°C, respectively.

[0161] Examples 1 to 19 of the reverse water gas shift catalyst cat1 of the present invention are shown in Table 1.

[0162] It should be noted that the horizontal axis represents the type of support CB1, the metal loading as the catalytically active component (wt%; marked as wt.%), CO adsorption capacity (ml / g), and BET surface area (m²). 2 / g).

[0163] It should be noted that, for CO adsorption capacity, the catalyst was subjected to a reduction pretreatment at 350°C under a hydrogen atmosphere for 1 hour before CO adsorption capacity was measured.

[0164] [Table 1]

[0165]

[0166] (Catalytic activity test)

[0167] The catalytic activity test was conducted using a mixture of 50% H2 and 50% CO2 (a 1:1 (volume ratio) H2 and CO2 mixture) as the reaction gas, with the reaction temperature changed at 50°C intervals between 600°C and 800°C under a GHSV (Gas Hourly Space Velocity) of 10,000 / h.

[0168] It should be noted that before conducting the catalytic activity test, hydrogen was flowed through the catalyst layer while the catalyst underwent a reduction pretreatment at 600°C.

[0169] As experimental results, the CO concentration (%), CH4 concentration (%), and CO2 conversion rate (%) at the outlet of the reaction section are recorded in Table 2.

[0170] It should be noted that the CO2 conversion rate (%) is based on the gas analysis results at the catalyst layer outlet and is calculated according to the following formula.

[0171] [CH4 concentration] + [CO concentration] / ([CH4 concentration] + [CO concentration] + [CO2 concentration])

[0172] As shown above, the reverse water gas shift catalyst cat1 used in the first catalytic reaction section 20 (reverse water gas shift reaction section) is expected to have a high CO2 conversion rate (%) on the high-temperature side (e.g., around 600~800°C).

[0173] [Table 2]

[0174]

[0175]

[0176] (Experimental Example 2)

[0177] The following describes the experimental results of Examples (20-29) of Experimental Example 2. In this example, Ni and Fe were studied as catalytically active components, and the addition of Cu was also investigated.

[0178] CeO2 (cerium oxide) and ZrO2 (zirconia) were used as supports in the examples, and Al2O3 (aluminum oxide) was also studied.

[0179] (Catalyst modulation)

[0180] For the reverse water-gas shift catalyst cat1 used in Experiment Example 2, except that the firing temperature was changed to 600℃, 800℃, and 1000℃, it was modulated in the same way as in Experiment Example 1.

[0181] Table 3 shows the respective catalysts for the modified examples (20-29).

[0182] [Table 3]

[0183]

[0184] (Catalytic activity test)

[0185] The catalytic activity test was conducted by using a 1:1 (volume ratio) mixture of H2 and CO2 as the reaction gas, and changing the reaction temperature at intervals of 50°C between 600°C and 800°C under a GHSV of 10000 / h.

[0186] It should be noted that before conducting the catalytic activity test, hydrogen was flowed through the catalyst layer while the catalyst underwent a reduction pretreatment at 600°C.

[0187] As experimental results, the CO concentration (%), CH4 concentration (%), and CO2 conversion rate (%) at the outlet of the reaction section are recorded in Table 4.

[0188] [Table 4]

[0189]

[0190] It should be noted that, for reference, the equilibrium value (calculated value) of CO2 conversion rate under the experimental conditions is shown in Table 4.

[0191] Iron-zirconium oxide catalysts and iron-alumina catalysts

[0192] For the iron-zirconia catalyst, the experimental results at calcination temperatures of 450°C, 600°C, 800°C, and 1000°C are shown in Examples 8, 22, 26, and 29, respectively. On the other hand, for the iron-alumina catalyst, the experimental results at calcination temperatures of 450°C, 600°C, and 800°C are shown in Examples 14, 23, and 27, respectively. These results show that, although the metal loading is slightly different, the iron-zirconia catalyst exhibits superior activity compared to the iron-alumina catalyst in the reverse water-gas shift reaction. Furthermore, the iron-zirconia catalyst maintains very high catalytic activity not only at a calcination temperature of 450°C, but also at calcination temperatures increased to 600°C, 800°C, and 1000°C, with the CO2 conversion rate reaching near the equilibrium value at any calcination temperature.

[0193] Nickel-cerium oxide catalyst

[0194] The experimental results at firing temperatures of 450℃, 600℃, 800℃, and 1000℃ are shown in Examples 4, 20, 24, and 28, respectively. These results demonstrate that the nickel-cerium oxide catalyst exhibits very high catalytic activity not only at a firing temperature of 450℃, but also at firing temperatures increased to 600℃, 800℃, and 1000℃, with the CO2 conversion rate reaching near the equilibrium value at any firing temperature.

[0195] Nickel-alumina catalyst

[0196] The results of the test at a firing temperature of 450°C are shown in Example 7. In these results, the nickel-alumina catalyst showed a lower CO2 conversion rate compared to the nickel-cerium oxide catalyst described above.

[0197] Nickel-copper-cerium oxide catalyst

[0198] The experimental results at firing temperatures of 450°C, 600°C, and 800°C are shown in Examples 6, 21, and 25, respectively. Based on these results, for the nickel-copper-cerium oxide catalyst, if the firing temperature is increased to 600°C or 800°C, the CO2 conversion rate tends to decrease slightly, but it is still superior to the iron-alumina catalyst under the same firing temperature conditions. Furthermore, for the nickel-copper-cerium oxide catalyst fired at 450°C, the CO2 conversion rate reaches near the equilibrium value.

[0199] Usefulness as a catalyst for reverse water gas shift reaction

[0200] As shown above, iron-zirconium oxide catalysts or nickel-cerium oxide catalysts exhibit very high reverse water-gas shift catalytic activity even when the calcination temperature is varied between 450°C and 1000°C. Therefore, they are useful, for example, when used in combination with solid oxide electrolyzers used in high-temperature zones around 600°C to 800°C.

[0201] Based on the above results, as shown above, the reverse water-gas shift catalyst cat1 used in the first catalytic reaction section 20 can be a catalyst composed of at least one or two of nickel and iron as catalytically active components ca1, supported on a carrier cb1 whose main components are cerium oxide-based metal oxides or zirconium oxide-based metal oxides. Furthermore, platinum can also be used, provided the cost is acceptable.

[0202] In addition, the cerium oxide metal oxide that serves as the carrier cb1 can also be cerium oxide doped with at least one of gadolinium, samarium, and yttrium.

[0203] In addition, the zirconium oxide metal oxide used as the carrier cb1 can also be at least one of the stable zirconium oxides, namely yttrium oxide and scandium oxide.

[0204] In addition, copper is preferred as another catalytically active component of Ca1, besides any one or two of nickel and iron.

[0205] Thus, by using the aforementioned reverse water gas shift catalyst cat1 in the first catalytic reaction section 20 (reverse water gas shift reaction section), the reverse water gas shift reaction can be carried out at around 600~1000°C with a CO2 conversion rate (%) that is equal to or higher than that of the highly active but very expensive Pt catalyst.

[0206] It should be noted that since the experiment in this embodiment was conducted under very high GHSV conditions of 10,000 / h, a higher CO2 conversion rate (%) can also be achieved by reducing the GHSV to less than 10,000 / h, i.e., by increasing the amount of catalyst used relative to the amount of gas processed.

[0207] [Combination of electrolysis reaction section and counter-current gas shift reaction section]

[0208] In the above explanation, based on Figure 1 The system structure shown is described in the order described, with the electrolysis reaction section 10 and the counter-current gas conversion reaction section 20 arranged along the gas advection direction.

[0209] The reaction in the electrolysis reaction section 10 is exothermic depending on the reaction conditions, while the reaction in the reverse water-gas shift reaction section 20 is endothermic. Therefore, by integrating these two reaction sections 10 and 20, the thermal efficiency of the system can be improved. Figure 3 This diagram illustrates the structure when the two reaction sections 10 and 20 are integrated into one unit, with the two parts enclosed to indicate that they are integrated. Furthermore, the reaction during this integration is shown within the frame. Equations 1, 2, and 3 shown above are essentially performed. It should be noted that when the electrolysis reaction section 10 and the counter-current gas shift reaction section 20 are integrated into one unit, it is preferable to enclose them together with a heat-insulating component, as this allows for efficient heat transfer between the electrolysis reaction section 10 and the counter-current gas shift reaction section 20. Additionally, to transfer the heat generated in the electrolysis reaction section 10 to the counter-current gas shift reaction section 20, a heat-transferring component can be used to connect the electrolysis reaction section 10 and the counter-current gas shift reaction section 20.

[0210] [An electrolytic cell unit that simultaneously possesses an electrolysis reaction section and a reverse water-gas conversion reaction section]

[0211] Based on the above concept, it is preferable to provide a reverse water-gas shift reaction unit 20 in the electrolytic cell unit U, which serves as the electrolysis reaction unit 10. This is because, when using a solid oxide type electrolytic cell that operates around 600~800°C as the electrolytic cell 1, the electrolysis reaction unit 10 and the reverse water-gas shift reaction unit 20 can be used in the same temperature range, since the highly active reverse water-gas shift catalyst cat1 of this application can be obtained around 600~800°C.

[0212] In this case, the gas passing through the electrolysis reaction section 10 can be introduced into the reverse water gas shift reaction section 20 to produce a reverse water gas shift reaction.

[0213] An electrolytic cell unit U, which is simultaneously equipped with such a reverse water gas shift reaction section 20, is shown in... Figure 4 middle. Figure 4 It is described by the direction of advection of the gas. Figure 2 A diagram of the electrolytic cell unit U shown in cross-section.

[0214] As shown in the figure, the cross-sections of the electrolytic cell unit U are basically the same.

[0215] That is, the electrolytic cell unit U also includes an electrolytic cell 1 that sandwiches an electrolyte layer 1a to form an electrode layer 2 and a counter electrode layer 3, a metal support 4 that functions as both a support and a separator, and supply passage forming components 5 and 6, forming a structure with an electrode layer-side gas supply passage 5a and a counter electrode layer-side gas supply passage 6a. To explain in more detail, as shown in the figure, if the metal support 4 is viewed in the direction of gas flow, a hole 4a is provided at the location corresponding to the electrolytic cell 1, but no hole is provided downstream of the electrode layer 2. Therefore, the metal support 4 serves as a separator that effectively separates the gas released from the electrode layer 2 while being supplied to it and the gas released from the counter electrode layer 3 while being supplied to it.

[0216] However, in this example, the reverse water-gas shift catalyst cat1 described above is coated on the inner surface of the gas supply passage 5a on the electrode layer side (the inner surface of the supply passage forming component 5 on the supply passage side, the surface of the metal support 4 opposite to the surface where the electrode layer 2 is formed, and the surface of the plurality of holes 4a). This coating layer 20a is indicated by a thick solid line.

[0217] Furthermore, the gas supply passage 5a on the electrode layer side extends forward beyond the electrolysis reaction section 10, and the aforementioned coating layer 20a is also provided on its extended side.

[0218] As a result, the gas supply passage 5a on the electrode layer side of the electrolytic cell unit U becomes an exhaust passage for discharging at least H2 generated in the electrode layer 2, and thus forms a structure in which the electrolytic reaction section 10 and the reverse water-gas conversion reaction section 20 are integrally integrated in the electrolytic cell unit U.

[0219] In this structure, the metal support 4 functions as a separator that separates the H2 generated in the electrode layer 2 from the O2 generated in the counter-electrode layer 3, and at least a portion of the H2 discharge passage side of the separator is the reverse water-gas shift reaction section 20.

[0220] Through Figure 2 , Figure 4 Electrolytic cell units U, stacked in this way in the left-right direction, can form a so-called electrolytic cell module (illustration omitted) by stacking multiple electrolytic cell units U and electrically connecting them. Of course, the generated useful gas can be obtained on multiple layers.

[0221] The inventors conducted experiments by combining the electrolysis reaction section 10 and the reverse water gas conversion reaction section 20 (using the gas supply passage 5a on the electrode layer side of the electrolysis reaction section 10 as the reverse water gas conversion reaction section 20) and storing granular reverse water gas conversion catalyst cat1 in the gas supply passage 5a on the electrode layer side.

[0222] exist Figure 5 The diagram shows a cross-section of the electrolytic cell unit U used in this experiment.

[0223] Refer to the following Figure 5 The following is a detailed explanation. A cross-sectional view of the electrolytic cell unit U is shown in the figure.

[0224] Here, a metal-supported solid oxide electrolytic cell is used as electrolytic cell 1. The metal support 4 is a ferritic stainless steel sheet with a thickness of 0.3 mm, through which multiple through holes (forming holes 4a) are formed to create a metal substrate. An electrode layer 2 and an intermediate layer 2a are sequentially stacked on this metal substrate. An electrolyte layer 1a is then stacked on the intermediate layer 2a of the metal substrate, covering the intermediate layer 2a. Furthermore, an anti-reaction layer 7 and a counter electrode layer 3 are sequentially stacked on the electrolyte layer 1a to create electrolytic cell 1. It should be noted that a mixture of NiO powder and GDC powder is used as the material for forming the electrode layer 2; GDC powder is used as the material for forming the intermediate layer 2a; 8YSZ (8 mol% yttrium-stabilized zirconium oxide) powder is used as the material for forming the electrolyte layer 1a; GDC powder is used as the material for forming the anti-reaction layer 7; and a mixture of GDC powder and LSCF powder is used as the material for forming the counter electrode layer 3. Furthermore, the thicknesses of electrode layer 2, intermediate layer 2a, electrolyte layer 1a, anti-reaction layer 7, and counter electrode layer 3 are approximately 25 μm, 10 μm, 5 μm, 5 μm, and 20 μm, respectively. It should be noted that by providing an intermediate layer 2a between electrode layer 2 and electrolyte layer 1a, or by providing an anti-reaction layer 7 between electrolyte layer 1a and counter electrode layer 3, the performance or durability of the electrolytic cell 1 can be improved. Additionally, the intermediate layer 2a or the anti-reaction layer 7 is preferably formed by a low-temperature firing method (e.g., a wet method that uses a low-temperature firing process instead of a high-temperature firing process above 1100°C), a spraying method (e.g., melt spraying, aerosol deposition, aerosol vapor deposition, powder spraying deposition, particle spraying deposition, cold spraying, etc.), PVD (sputtering, pulsed laser deposition, etc.), CVD, etc. These processes, which can be used in low-temperature regions, allow for the production of a good intermediate layer 2a or an anti-reaction layer 7 without the need for firing in high-temperature regions, such as above 1100°C. Therefore, an electrolytic cell 1 with excellent performance or durability can be achieved without damaging the metal support 4, which is preferable. Furthermore, the use of a low-temperature firing method simplifies the handling of raw materials, making it even more preferable.

[0225] For the electrolytic cell unit U obtained as described above, the performance improvement of the granular reverse water gas shift catalyst cat1 was studied when it was contained in the gas supply passage 5a on the electrode layer side (which also serves as the discharge passage for the gas electrolyzed in the electrolysis reaction section 10).

[0226] Results when the reverse water gas shift catalyst cat1 was not included

[0227] While supplying a gas containing H2O and CO2 to electrolytic cell unit U, an electrolysis reaction was carried out, and the ratio of H2 to CO in the outlet gas of electrolytic cell unit U was determined using a gas chromatograph. The results are shown in Table 5 below. These experimental results are recorded as comparative examples A1 and A2.

[0228] [Table 5]

[0229] Inlet gas Electrolysis voltage (V) Reaction temperature (°C) <![CDATA[H2 / CO ratio of the outlet gas]]> Comparative Example A1 <![CDATA[52% H2O - 13% CO2 - N2 balance]]> 1.2 700 14.2 Comparative Example A2 <![CDATA[49% H2O - 17% CO2 - N2 balance]]> 1.2 700 9.9

[0230] Results of collecting the reverse water gas shift catalyst cat1

[0231] As the reverse water-gas shift catalyst cat1, a granular catalyst, identical to that in Example 2, was prepared by loading approximately 10% Ni onto an 8YSZ support. Electrolysis was carried out while supplying a gas containing H2O and CO2 to the electrolytic cell unit U. The ratio of H2 to CO in the outlet gas of the electrolytic cell unit U was determined using gas chromatography. The results are shown in Table 6. This experimental result is recorded as Example A1.

[0232] [Table 6]

[0233] Inlet gas Electrolysis voltage (V) Reaction temperature (°C) <![CDATA[H2 / CO ratio of the outlet gas]]> Example A1 <![CDATA[51% H2O - 16% CO2 - N2 equilibrium]]> 1.15 700 5.4

[0234] Based on the above comparative experiments, the electrolytic cell 1 is formed as a thin layer on the metal support 4, and the reverse water gas shift reaction unit 20, which generates CO using CO2 and the aforementioned H2 through the reverse water gas shift reaction, is installed in the electrolytic cell unit U, which is the gas supply passage 5a on the electrode layer side, which serves as the discharge passage for the electrolyzed gas. This can improve the composition ratio of CO to H2 generated by electrolysis.

[0235] In a comparison of the electrolytic cell unit U without the reverse water-gas shift catalyst cat1 in the gas supply passage 5a (which becomes the discharge passage for the electrolyzed gas) on the electrode layer side, and the electrolytic cell unit U with the catalyst cat1, the outlet hydrogen / carbon monoxide ([H2 / CO]) ratio changes from about 10 or more to about 5. By combining the reaction of the electrolysis reaction section 10 with the reaction of the reverse water-gas shift reaction section 20, the amount of CO that is beneficial for the synthesis of various hydrocarbons can be ensured, which is therefore preferred. Furthermore, compared with the methanation reaction of CO2, the methanation reaction of CO can improve the thermal efficiency of the hydrocarbon preparation system 100. Therefore, by combining the reaction of the electrolysis reaction section 10 with the reaction of the reverse water-gas shift reaction section 20, the amount of CO can be ensured, which is also preferred. This is because, when 1 mole of CO2 is methanated, 2 moles of H2O are generated, while when 1 mole of CO is methanated, only 1 mole of H2O is generated. Therefore, the hydrocarbon preparation system 100 using the CO methanation reaction can suppress the loss of latent or sensible heat of 1 mole of H2O in the system as a whole.

[0236] It should be noted that by appropriately adjusting the ratio of H2O to CO2 introduced into the electrolysis reaction section 10, or the reaction conditions of the electrolysis reaction section 10 (electrolysis voltage or reaction temperature, etc.), and the reaction conditions of the reverse water gas shift reaction section 20 (amount of catalyst used or GHSV, reaction temperature, etc.), the hydrogen / carbon monoxide ([H2 / CO]) ratio at the outlet of the reverse water gas shift reaction section 20 can be adjusted to a value suitable for the subsequent second catalytic reaction section 30 (hydrocarbon synthesis reaction section) (e.g., the equivalent ratio of CO methanation reaction H2 / CO = 3, etc.).

[0237] A heat exchange section is installed between the electrolysis reaction section and the reverse water-gas shift reaction section.

[0238] The above description primarily focuses on an example of integrating the electrolysis reaction section 10 and the first catalytic reaction section (reverse water-gas shift reaction section) 20. However, a structure can also be adopted in which a heat exchange section 11 is provided between the two sections 10 and 20, allowing heat flow between them. For example, in the example described above... Figure 4 In the structure, the reverse water-gas shift reaction section 20 is extended downstream, and a heat exchange layer with high thermal conductivity is additionally provided between it and the extended section. This structure is combined with... Figure 1 Correspondingly shown in Figure 6 In the middle, the hollow double lines represent thermal movement between the two parts. In this structure, the temperatures of 10 and 20 degrees Celsius in each part can be appropriately controlled.

[0239] The inventors refer to the system described above, consisting of the electrolysis reaction section 10 and the reverse water-gas conversion reaction section 20, as the "electrolysis reaction system".

[0240] [Second Catalytic Reaction Section (Hydrocarbon Synthesis Reaction Section)]

[0241] In the second catalytic reaction section 30 (hydrocarbon synthesis reaction section), at least H2 and CO flow in, and hydrocarbons (methane or various hydrocarbons with more than 2 carbon atoms) are generated through catalytic reaction.

[0242] (Examples of hydrocarbon synthesis catalysts)

[0243] As an activity test of the catalyst (hydrocarbon synthesis catalyst cat2) used in the second catalytic reaction section 30, the inventors conducted the following evaluation test 1, evaluation test 2 and evaluation test 3.

[0244] It should be noted that, as an example of a hydrocarbon synthesis catalyst, cat2, various modifications were made to the support or catalytically active component to modulate the catalyst. For catalytically active component ca2, Ru was used, and compositions obtained by adding Mo, V, Fe, Co, etc., to Ru were studied, as well as Ni. For support cb2, ZrO2, Al2O3, SiO2, MgO, and TiO2 were investigated.

[0245] (Catalyst modulation)

[0246] The modulation of the hydrocarbon synthesis catalyst cat2 is also carried out using Figure 11 , 12 The method described in the text.

[0247] That is, based on the composition of the target catalyst, an aqueous solution containing a quantitative amount of water-soluble ruthenium compounds (ruthenium nitrate, ruthenium chloride, ruthenium sulfate, ruthenium ammonium sulfate, ruthenium acetate, ruthenium oxalate, ruthenium citrate, etc.) is obtained. Similarly, when molybdenum, vanadium, iron, and cobalt are supported as other catalytic active components, aqueous solutions containing the same quantitative amounts of water-soluble metal compounds are obtained. Using this aqueous solution, the catalytic active component is impregnated onto a specified amount of support particles (ZrO2, Al2O3, SiO2, MgO, TiO2), and then subjected to necessary processing steps such as drying, calcination, or reduction treatment to obtain the hydrocarbon synthesis catalyst cat2.

[0248] It should be noted that the catalysts in the following embodiments were prepared using aqueous solutions of ruthenium chloride, ammonium molybdate, vanadium oxalate, ferric nitrate, and cobalt nitrate, respectively. When ruthenium and other catalytically active components were simultaneously loaded, a successive loading method (a two-step loading method in which the catalytically active components other than ruthenium were first loaded onto the support, and then ruthenium was loaded) was used.

[0249] (Evaluation Experiment 1)

[0250] In evaluation experiment 1, a mixed gas containing 12.4% CO, 24.8% CO2, 37.2% H2, 12.4% H2O, and the balance being N2 was used as the reaction gas. GHSV was set to 4000 / h (wet basis), and the activity test of the hydrocarbon synthesis catalyst cat2 was conducted at a reaction temperature between 275℃ and 360℃. It should be noted that the reaction gas at this time is an example of the following hypothetical model: under the condition of low carbon dioxide electrolysis reaction rate, water and carbon dioxide co-electrolysis reaction is carried out in the electrolysis reaction section 10, and after the reverse water-gas shift reaction of carbon dioxide is carried out in the reverse water-gas shift reaction section 20 set in the subsequent section, the mixed gas of CO, CO2, H2, and H2O is introduced into the hydrocarbon synthesis reaction section 30 to carry out the hydrocarbon synthesis reaction.

[0251] The following two indicators were used when compiling the experimental results.

[0252] 1. Hypothetical hydrocarbon conversion rate after CO2 removal = [Number of carbon atoms in the outlet gas] / [Number of carbon atoms in the outlet gas - Number of carbon atoms in the outlet CO2]

[0253] This indicator represents the conversion rate of CO2 to hydrocarbons when CO2 is removed from the outlet gas of the hydrocarbon synthesis reaction section 30 obtained through catalytic reaction, and this indicator is preferably high.

[0254] 2. Heat release of C1-C4 (MJ / Nm³) 3 )=Σ(Nn×HN) / ΣNn

[0255] Nn [mol]: The number of moles of Cn hydrocarbons in the gas of the catalytic reaction section (n=1~4)

[0256] HN [MJ / m 3 [(N)]: The heat released by Cn hydrocarbons in the gas of the catalytic reaction section.

[0257] [H1=39.8, H2=69.7, H3=99.1, H4=128.5]

[0258] This index indicates the amount of C1 to C4 components contained in the outlet gas of the hydrocarbon synthesis reaction section 30 obtained through catalytic reaction. When this value exceeds 39.8, in addition to methane, hydrocarbons such as ethane, propane, and butane can also be confirmed to have been generated.

[0259] For evaluation test 1, Examples B1 to B3 of the hydrocarbon synthesis catalyst cat2 of the present invention are shown in Tables 7 and 8 below.

[0260] [Table 7]

[0261]

[0262] [Table 8]

[0263]

[0264] As shown in Tables 7 and 8, it can be confirmed that hydrocarbons can be synthesized using a mixture of CO, CO2, H2, and H2O as a hydrocarbon synthesis catalyst (cat2) supported on an alumina support, or a catalyst supported on molybdenum or vanadium in addition to ruthenium.

[0265] The above results confirm that the hydrocarbon preparation system 100 described above can generate C1-C4 hydrocarbons with an exothermic heat of 39 MJ / Nm³. 3 The above are high-calorific-value gases.

[0266] (Evaluation Experiment 2)

[0267] In evaluation experiment 2, a mixed gas containing 0.45% CO, 18.0% CO2, 71.55% H2, and 10.0% H2O was used as the reaction gas. The GHSV was set to 5000 / h (dry basis), and the activity test of the hydrocarbon synthesis catalyst cat2 was conducted at a reaction temperature between approximately 230°C and approximately 330°C. It should be noted that the reaction gas in this case is an example of the following hypothetical model: under conditions of low carbon dioxide electrolysis reaction rate, a co-electrolysis reaction of water and carbon dioxide is carried out in the electrolysis reaction section 10, and the resulting mixed gas is introduced into the hydrocarbon synthesis reaction section 30 to carry out the hydrocarbon synthesis reaction.

[0268] The following two indicators were used when compiling the experimental results.

[0269] 1. Hydrocarbon conversion rate = [Number of carbon atoms in the hydrocarbons in the outlet gas] / [Number of carbon atoms in the outlet gas]

[0270] This indicator represents the proportion of carbon that is converted into hydrocarbons instead of CO2 out of all incoming carbon, and a high value is preferred.

[0271] 2. Hypothetical hydrocarbon conversion rate after CO2 removal = [Number of carbon atoms in the hydrocarbons in the outlet gas] / [Number of carbon atoms in the outlet gas - Number of carbon atoms in the outlet CO2]

[0272] This indicator represents the conversion rate of CO2 to hydrocarbons when CO2 is removed from the outlet gas of the hydrocarbon synthesis reaction unit obtained through catalytic reaction, and this indicator is preferably high.

[0273] For evaluation test 2, the catalysts used (Examples B4 to B16) are shown in Table 9, and the test results are shown in Table 10.

[0274] [Table 9]

[0275]

[0276] [Table 10]

[0277]

[0278]

[0279] (Evaluation Experiment 3)

[0280] In evaluation experiment 3, a mixed gas containing H2 and CO at a volume ratio of 3:1 (H2 / CO=3) was used as the reaction gas. The GHSV was set to 4000 / h, and the activity test of the hydrocarbon synthesis catalyst cat2 was conducted at a reaction temperature between 235°C and approximately 330°C. In this activity test, a catalyst supported on a titanium dioxide support and loaded with iron or cobalt in addition to ruthenium was used (Examples B17, B18). It should be noted that the reaction gas at this time is an example of a hypothetical model: a mixed gas containing carbon monoxide added to hydrogen obtained from the electrolysis of water in the electrolysis reaction section 10, or a mixed gas of hydrogen and carbon monoxide obtained by separating water or carbon dioxide from the gas obtained from the co-electrolysis of water and carbon dioxide as needed, is introduced into the hydrocarbon synthesis reaction section 30 to carry out the hydrocarbon synthesis reaction.

[0281] The results of evaluation test 3 are shown in Table 11.

[0282] [Table 11]

[0283]

[0284] As shown in Table 11, it can be confirmed that hydrocarbons can be synthesized using a mixed gas containing H2 and CO as the hydrocarbon synthesis catalyst cat2, and using a catalyst supported on a titanium dioxide support with ruthenium and iron or cobalt.

[0285] It can be confirmed that the hydrocarbon preparation system 100 described above can generate C1-C4 hydrocarbons with an exothermic heat of 39 MJ / Nm³. 3 The above are high-calorific-value gases.

[0286] Based on the above results, as shown above, a catalyst with at least ruthenium supported on a metal oxide support cb2 as the catalytic active component Ca2 can be used in the second catalytic reaction section 30 (hydrocarbon synthesis reaction section). Preferably, at least one of molybdenum, vanadium, iron, and cobalt is also supported as the catalytic active component Ca2.

[0287] It should be noted that, as a hydrocarbon synthesis catalyst, cat2 is preferably a catalyst on which at least ruthenium is loaded on a metal oxide support cb2, and the loading amount of ruthenium is more than 0.1% by weight and less than 5% by weight. Alternatively, in addition to ruthenium, at least one of molybdenum, vanadium, iron and cobalt is also loaded on the metal oxide support cb2 as a catalytic active component, which is ca2.

[0288] Here, the loading of at least one of the above-mentioned molybdenum, vanadium, iron, and cobalt can be more than 0.2% by weight and less than 6% by weight.

[0289] In addition, in such a hydrocarbon synthesis catalyst cat2, the carbon monoxide adsorption capacity of the highly active catalyst is above 0.4 ml / g.

[0290] [Heavy Hydrocarbon Separation Section]

[0291] By cooling the gas arriving at the heavy hydrocarbon separation section 35, the heavy hydrocarbons contained in the gas released from the hydrocarbon synthesis reaction section 30 are condensed, and the heavy hydrocarbons can be removed to the outside. For example, in the hydrocarbon synthesis reaction section 30 using the 2wt.%Ru / 2wt.%Fe / TiO2 catalyst shown in Example B17 above, when a mixed gas containing H2 and CO in a 3:1 (volume ratio) (H2 / CO=3) is introduced and the reaction is carried out at 275°C, straight-chain higher aliphatic hydrocarbons with an average chain length of 26 carbon atoms can be removed from the heavy hydrocarbon separation section 35, and when the reaction is carried out at 325°C, straight-chain higher aliphatic hydrocarbons with an average chain length of 18 carbon atoms can be removed from the heavy hydrocarbon separation section 35.

[0292] [Water Separation Section]

[0293] A condenser is installed in the water separation section 40 to adjust the incoming gas containing H2O to a specified temperature and pressure, so that it condenses and the water is extracted to the outside.

[0294] [Carbon Dioxide Separation Section]

[0295] For example, a PSA is configured in this section 50, which adsorbs onto the adsorbent under specified temperature and pressure to separate CO2 from the incoming CO2-containing gas, while simultaneously removing the separated CO2 from the adsorbent, thereby effectively separating CO2. The separated CO2 can be returned to the front of the electrolysis reaction section 10 via the carbon dioxide return passage 51 for reuse.

[0296] It should be noted that PSA or similar devices can also be used to make the carbon dioxide separation section and the water separation section the same separation section.

[0297] [Other Implementation Methods]

[0298] (1) In the above embodiment, the CO2 separated in the carbon dioxide separation unit 50 is returned to the front of the electrolysis reaction unit 10. However, in the hydrocarbon preparation system 100 according to the present invention, the conversion of CO2 to CO mainly takes place in the reverse water-gas shift reaction unit 20. Therefore, the destination for returning CO2 can be set to the front of the reverse water-gas shift reaction unit 20. This structure is shown in Figure 7 middle.

[0299] (2) In the above embodiment, regarding H2 in the gas obtained from the hydrocarbon synthesis reaction unit 30, although not specifically mentioned, a hydrogen separation unit (shown as H2 separation unit in the figure) 60 that uses a hydrogen separation membrane or the like to separate H2 can be provided to separate H2 for separate use. This structure is shown in Figure 8In this example, the return destination of the H2 separated in the hydrogen separation unit 60 can be set in front of the reverse water-gas shift reaction unit 20 for reverse water-gas shift reaction.

[0300] (3) In the above embodiment, the water separation unit 40 is disposed downstream of the hydrocarbon synthesis reaction unit 30, but if Figure 9 As shown, a water separation unit 40 can also be provided between the reverse water-gas shift reaction unit 20 and the hydrocarbon synthesis reaction unit 30. The main function of the water separation unit 40 is to facilitate the hydrocarbon synthesis reaction.

[0301] (4) In the above embodiment, an example is shown of supplying both H2O and CO2 to the electrolysis reaction section 10 for electrolysis reaction, but as Figure 10 As shown, it is also possible to supply only H2O to the electrolysis reaction section 10 for the electrolysis reaction. In this case, the carbon consumed in hydrocarbon synthesis is fed into the reverse water-gas shift reaction section 20 as carbon dioxide.

[0302] (5) In the above embodiment, an example of using a solid oxide type electrolytic cell as electrolytic cell 1 in the electrolysis reaction section 10 is shown. However, as electrolytic cell 1, an alkaline electrolytic cell or a polymer membrane type electrolytic cell may also be used.

[0303] (6) In the above embodiment, a structure in which the electrolysis reaction section 10 and the first catalytic reaction section 20 are integrated is shown. However, in addition to these reaction sections 10 and 20, the second catalytic reaction section 30 may also be integrated. An example of this type of structure is shown below. Figure 13 In the middle. By the way, in this figure, 30a represents the coating layer of the hydrocarbon synthesis catalyst cat2.

[0304] In this configuration, the reaction sections 10, 20, and 30 can also be constructed on the metal support 4 and the supply passage forming component 5, with the metal support 4 acting as a separator for separating the generated hydrocarbons and oxygen.

[0305] (7) In the above embodiment, an example of synthesizing hydrocarbons such as methane in the hydrocarbon synthesis reaction section 30 is shown. However, depending on the method of selecting the hydrocarbon synthesis catalyst used in the hydrocarbon synthesis reaction section 30, chemical raw materials such as hydrogen and carbon monoxide introduced into the hydrocarbon synthesis reaction section 30 can also be used to synthesize the hydrocarbons.

[0306] Marker description

[0307] 1 Electrolytic cell

[0308] 1a Electrolyte layer

[0309] 2 Electrode layer

[0310] 3. Counter electrode layer

[0311] 4. Metal support structure (support / partition)

[0312] 4a Hole (Through Hole)

[0313] 5. Supply path forming components (partitions)

[0314] 6. Supply path forming component (partition)

[0315] 10 Electrolysis Reaction Section

[0316] 20. First Catalytic Reaction Section (Reverse Water-Gas Shift Reaction Section)

[0317] 20a Coating Layer

[0318] 30. Second Catalytic Reaction Section (Hydrocarbon Synthesis Reaction Section)

[0319] 40 Water Separation Section

[0320] 50 Carbon Dioxide Separation Unit

[0321] 60 Hydrogen Separation Section

[0322] U Electrolyte Cell Unit

[0323] cat1 Reverse Water Gas Shift Catalyst

[0324] CA1 catalytically active ingredient

[0325] cb1 carrier

[0326] cat2 hydrocarbon synthesis catalyst

[0327] Ca2+ catalytic active ingredient

[0328] cb2 carrier.

Claims

1. An electrolytic cell unit, the electrolytic cell unit being configured to include at least: an electrolytic cell having an electrode layer and a counter electrode layer sandwiched between an electrolyte layer, and a discharge passage for discharging hydrogen generated in the electrode layer. in, The electrolytic cell is formed as a thin layer on one side of the support, and the discharge passage is provided along the other side of the support. At least a portion of the discharge passage is provided with a reverse water gas shift reaction section, which contains a granular reverse water gas shift catalyst for generating carbon monoxide using carbon dioxide and hydrogen through a reverse water gas shift reaction. The electrolytic cell unit includes a separator that separates the hydrogen generated in the electrode layer and the oxygen generated in the counter electrode layer, and the reverse water gas shift reaction section is provided on at least a portion of the hydrogen discharge passage side of the separator.

2. The electrolytic cell unit according to claim 1, wherein, The support is made of metal.

3. The electrolytic cell unit according to claim 1 or 2, wherein, Multiple through holes are provided through the support body, and the electrode layer is provided on one side of the support body. At the same time, at least a portion of the inner surface of the discharge passage serves as the reverse water gas conversion reaction section.

4. The electrolytic cell unit according to claim 1, wherein, The partition is made of metal.

5. The electrolytic cell unit according to claim 1 or 2, wherein, The reverse water gas shift catalyst is a catalyst on which metal or metal oxide is supported.

6. The electrolytic cell unit according to claim 1 or 2, wherein, The reverse water gas shift catalyst is a catalyst containing at least one of platinum, nickel, and iron.

7. The electrolytic cell unit according to claim 5, wherein, The carrier is a carrier whose main components are cerium oxide-based metal oxides or zirconium oxide-based metal oxides.

8. Electrolytic cell apparatus, wherein, It comprises at least: an electrolytic cell unit according to any one of claims 1 to 7, an electrolytic raw material supply unit for supplying water and / or water vapor and carbon dioxide to the electrolytic cell unit, and an electric power supply unit for supplying electricity.

9. Hydrocarbon preparation system, wherein, It comprises: an electrolytic cell unit according to any one of claims 1 to 7 or an electrolytic cell apparatus according to claim 8, and a hydrocarbon synthesis reaction unit for reacting the hydrogen and the carbon monoxide to generate hydrocarbons.

10. A method for preparing an electrolytic cell unit, the electrolytic cell unit being configured to include at least: an electrolytic cell having an electrode layer and a counter electrode layer sandwiched between an electrolyte layer, and a discharge passage for discharging hydrogen generated in the electrode layer, the electrolytic cell being formed as a thin layer on one side of a support, the discharge passage being provided along the other side of the support, and at least a portion of the discharge passage being provided with: a reverse water gas shift reaction section for storing a granular reverse water gas shift catalyst for generating carbon monoxide using carbon dioxide and the hydrogen through a reverse water gas shift reaction. The electrolytic cell unit includes a separator that separates the hydrogen generated in the electrode layer and the oxygen generated in the counter electrode layer, and the reverse water-gas shift reaction section is provided on at least a portion of the hydrogen discharge passage side of the separator. in, In the formation process of the reverse water gas conversion reaction section, there is at least a firing process in which firing is carried out at a temperature of 450°C or higher.

11. A method of using an electrolytic cell unit, wherein the electrolytic cell unit is configured to include at least: an electrolytic cell having an electrode layer and a counter electrode layer sandwiched between an electrolyte layer, and a discharge passage for discharging hydrogen generated in the electrode layer, the electrolytic cell being formed as a thin layer on one side of a support, the discharge passage being provided along the other side of the support, and at least a portion of the discharge passage being provided with: a reverse water gas shift reaction section for storing a granular reverse water gas shift catalyst for generating carbon monoxide using carbon dioxide and the hydrogen through a reverse water gas shift reaction. The electrolytic cell unit includes a separator that separates the hydrogen generated in the electrode layer and the oxygen generated in the counter electrode layer, and the reverse water-gas shift reaction section is provided on at least a portion of the hydrogen discharge passage side of the separator. in, The reverse water gas shift reaction unit is used after the reduction pretreatment is performed.

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