Reaction system, method for capturing solid carbon, method for producing gas containing hydrogen, catalyst set, and catalyst for capturing solid carbon

Abstract

The present invention discloses a reaction system which comprises: a reforming device that is provided with a reaction tube and a reforming catalyst for the generation of carbon monoxide from a starting material gas that contains a hydrocarbon, said reforming catalyst being arranged within the reaction tube; a solid carbon collection device that is provided with a reaction tube and a catalyst for solid carbon collection, said catalyst being arranged within the reaction tube; and a flow path which enables a gas to flow from the reforming device to the solid carbon collection device. The catalyst for solid carbon collection has a base material and a coating layer that is formed on the surface of the base material. The coating layer contains at least one metal-containing component that is selected from among iron oxide, cobalt oxide and the like.

Description

[Technical Field]

[0001] The present disclosure relates to a reaction system, a method for capturing solid carbon, a method for producing a gas containing hydrogen, a catalyst set, and a catalyst for capturing solid carbon. [Background technology]

[0002] In order to reduce carbon dioxide emissions, efforts to capture and store carbon dioxide are gaining momentum worldwide. From the perspective of efficient storage, it is desirable to store carbon dioxide in a solid state, which has a smaller volume than gas. Therefore, development of technologies involving methanation of carbon dioxide and precipitating solid carbon from methane, as shown in the following reaction formula, is underway (for example, Patent Document 1, Non-Patent Document 1). CO2 + 4H2 → CH4 + 2H2O (methanation) CH4 → C + 2H2 (solid carbonization) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-196619 [Non-patent literature]

[0004] [Non-Patent Document 1] Upham et al., Science, 358, 917-921 (2017) Nov. 2017 Summary of the Invention [Problem to be solved by the invention]

[0005] However, reactions to directly produce solid carbon from hydrocarbons such as methane often require heating at extremely high temperatures of over 1000°C. From the perspective of reducing carbon dioxide emissions, it would be desirable to be able to produce solid carbon at lower temperatures.

[0006] One aspect of the present disclosure relates to a reaction system that enables efficient capture of solid carbon from a gas containing a carbon source at relatively low temperatures. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to a solid carbon capture catalyst having a substrate and a coating layer formed on the surface of the substrate. The coating layer contains at least one metal-containing component selected from the group consisting of iron oxide, cobalt oxide, magnesium oxide, molybdenum oxide, nickel oxide, manganese oxide, metallic iron, metallic cobalt, metallic magnesium, metallic molybdenum, metallic nickel, and metallic manganese. This solid carbon capture catalyst is used, for example, in combination with a reforming catalyst that produces carbon monoxide from a hydrocarbon-containing feed gas.

[0008] Another aspect of the present disclosure relates to a solid carbon capture device including a reaction tube and the above-described solid carbon capture catalyst provided in the reaction tube.

[0009] Yet another aspect of the present disclosure relates to a method for capturing solid carbon, comprising supplying a feed gas containing at least one of hydrocarbons and carbon monoxide to the solid carbon capture device while heating the solid carbon capture catalyst, thereby depositing solid carbon on the solid carbon capture catalyst.

[0010] Yet another aspect of the present disclosure relates to a reaction system including a reaction tube, a reformer provided in the reaction tube and including a reforming catalyst for producing carbon monoxide from a feed gas containing hydrocarbons, and the solid carbon capture device. A flow path is formed through which gas flows from the reformer to the solid carbon capture device. The reforming catalyst may be a dry reforming catalyst for producing carbon monoxide and hydrogen from a feed gas containing hydrocarbons and carbon dioxide, or may be a steam reforming catalyst for producing carbon monoxide, carbon dioxide, and hydrogen from a feed gas containing hydrocarbons and water.

[0011] Yet another aspect of the present disclosure relates to a method for capturing solid carbon, comprising supplying a feed gas containing hydrocarbons to the reaction system while heating the reforming catalyst and the solid carbon capture catalyst, thereby depositing solid carbon on the solid carbon capture catalyst.

[0012] Yet another aspect of the present disclosure relates to a method for producing a gas containing hydrogen, comprising capturing solid carbon by the above-described method and discharging an exhaust gas containing hydrogen from the solid carbon capture device.

[0013] Yet another aspect of the present disclosure relates to a catalyst set including a reforming catalyst for producing carbon monoxide from a hydrocarbon-containing feed gas and a solid carbon capture catalyst. The solid carbon capture catalyst has a substrate and a coating layer formed on the surface of the substrate. The coating layer contains at least one metal-containing component selected from the group consisting of iron oxide, cobalt oxide, magnesium oxide, molybdenum oxide, nickel oxide, manganese oxide, metallic iron, metallic cobalt, metallic magnesium, metallic molybdenum, metallic nickel, and metallic manganese. [Effects of the Invention]

[0014] According to one aspect of the present disclosure, there is provided a catalyst that enables efficient capture of solid carbon at relatively low temperatures, and a solid carbon capture device and reaction system including the same. Combining such a solid carbon capture device with a reformer including a reforming catalyst that produces carbon monoxide from a feed gas containing hydrocarbons enables efficient capture of solid carbon and efficient production of a gas containing hydrogen through a solid carbonization reaction including the Boudouard reaction that produces solid carbon from carbon monoxide. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a solid carbon capture catalyst. [Figure 2] FIG. 1 is a schematic diagram illustrating an example of a solid carbon capture device. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of a reaction system. [Figure 4] FIG. 1 is a schematic diagram illustrating an example of a reaction system. [Figure 5] 1 is a graph showing the conversion rate and H2 / CO (molar ratio) versus time for dry reforming of CH4 and CO2 when the carbon capture catalyst contains iron oxide (Fe3O4). [Figure 6] 1 is a graph showing the carbon capture efficiency relative to the total carbon amount of CH 4 and CO 2 in the raw material gas. [Figure 7] 1 is a graph showing the relationship between time and the conversion rate of CH and CO and the H / CO (molar ratio) in dry reforming when the carbon capture catalyst contains iron oxide (FeO) and its temperature is 450°C, and also the relationship between time and the proportions of hydrogen, carbon dioxide, carbon monoxide, and methane in the exhaust gas. [Figure 8] 1 is a scanning electron microscope photograph of solid carbon deposited on a carbon capture catalyst containing Fe3O4. [Figure 9] 1 is a graph showing the relationship between CH4 and CO2 conversion and H2 / CO (molar ratio) versus time for dry reforming when the carbon capture catalyst contains iron oxide (Fe2O3) and is at a temperature of 470°C. [Figure 10] 1 is a graph showing the relationship between CH4 and CO2 conversion and H2 / CO (molar ratio) versus time for dry reforming when the carbon capture catalyst contains Fe / Al2O3. [Figure 11] 1 is a graph showing the proportions of hydrogen, carbon dioxide, carbon monoxide, and methane in the exhaust gas of dry reforming versus time when the carbon capture catalyst includes Fe / Al 2 O 3 . [Figure 12] 1 is a scanning electron microscope photograph of solid carbon deposited on a carbon capture catalyst containing Fe / Al2O3. [Figure 13] 1 is a graph showing the relationship between time and the conversion rate (conversion) and H / CO (molar ratio) of CH steam reforming (SRM) when the carbon capture catalyst contains iron oxide (FeO), and the relationship between time and the amounts of hydrogen, carbon dioxide, methane, and carbon monoxide in the exhaust gas. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure is not limited to the following examples.

[0017] Fig. 1 is a cross-sectional view showing an example of a solid carbon capture catalyst. The solid carbon capture catalyst 5 shown in Fig. 1 has a tubular substrate 1 and a coating layer 3 formed on the inner wall surface of the substrate 1.

[0018] When the substrate 1 is a tubular body as in the embodiment of FIG. 1 , the raw material gas can easily flow through the solid carbon capture catalyst 5. Furthermore, the fewer structures inside the tubular body that obstruct flow, the less likely clogging due to precipitated solid carbon occurs. The substrate 1 is not particularly limited as long as it can be coated with a metal-containing component, but it may be, for example, a stainless steel pipe or an aluminum pipe. When the substrate 1 is a tubular body having an inner wall surface with a circular cross section, its inner diameter is not particularly limited, but may be, for example, 10 to 300 mm or 10 to 1000 mm. When the substrate 1 is a tubular body, its length is not particularly limited, but may be, for example, 20 to 5000 mm. The substrate 1 may be a tubular body extending linearly or a twisted tubular body.

[0019] The shape of the substrate constituting the solid carbon capture catalyst is not limited to a tubular body, and may have any shape. For example, the substrate may be a flat body (plate-like body) or a spiral body, or may be a twisted flat body or spiral body.

[0020] The coating layer 3 contains, as a main component, at least one metal-containing component selected from the group consisting of iron oxide, cobalt oxide, magnesium oxide, molybdenum oxide, nickel oxide, manganese oxide, metallic iron, metallic cobalt, metallic magnesium, metallic molybdenum, metallic nickel, and metallic manganese. The coating layer 3 may contain iron oxide, particularly Fe3O4, Fe2O3, FeO, or a combination thereof. The proportion of these metal-containing components in the coating layer 3 may be 40 to 100 mass%, 50 to 100 mass%, 60 to 100 mass%, 70 to 100 mass%, 80 to 100 mass%, or 90 to 100 mass%, based on the mass of the coating layer 3. The coating layer 3 may also contain a support containing aluminum oxide (Al2O3) and metallic iron supported on the support. In this case, the proportion of metallic iron may be 40 to 50 mass%, based on the mass of the coating layer 3.

[0021] The coating layer 3 is formed so as to cover the entire or part of the surface (inner wall surface) of the substrate 1. The thickness of the coating layer 3 is not particularly limited, but may be, for example, 5 to 2000 μm, or 10 to 2000 μm.

[0022] From the viewpoint of efficient deposition of solid carbon, the coating layer 3 may be porous. The specific surface area of ​​the porous coating layer is 5 to 1000 m 2 / g.

[0023] The coating layer can be formed, for example, by a method including: applying a coating liquid containing at least one metal-containing component selected from the group consisting of iron oxide, cobalt oxide, magnesium oxide, molybdenum oxide, nickel oxide, manganese oxide, metallic iron, metallic cobalt, metallic magnesium, metallic molybdenum, metallic nickel, and metallic manganese, or a precursor thereof, and a solvent, to the surface (e.g., inner wall surface) of the substrate 1; and removing the solvent from the coating liquid applied to the surface of the substrate 1. The solvent for the coating liquid may be, for example, water, alcohol, acetone, or a combination thereof.

[0024] Fig. 2 is a schematic diagram showing one embodiment of a solid carbon collector equipped with a solid carbon capture catalyst. The solid carbon collector 20 shown in Fig. 2 includes a reaction tube 21 and the above-mentioned solid carbon capture catalyst 5 provided in the reaction tube 21. The solid carbon collector 20 further includes a heater 22 provided around the reaction tube 21. Pipes 40 for gas circulation are connected to both ends of the reaction tube 21. A raw material gas G1 is supplied from one of the pipes 40, and an exhaust gas G2 is discharged from the other pipe 40. A valve 31 is provided on the upstream pipe 40, and a valve 32 is provided on the downstream pipe 40.

[0025] By supplying the raw material gas G1 while heating the solid carbon capture catalyst 5 with the heater 22, solid carbon is precipitated on the coating layer of the solid carbon capture catalyst 5. The precipitated solid carbon can be easily peeled off from the coating layer. For example, multiple reaction tubes can be prepared, and the reaction tubes before and after carbon capture can be exchanged using a revolver system. This allows solid carbon to be efficiently captured.

[0026] The source gas G1 contains a carbon compound that generates solid carbon. For example, the source gas G1 may contain at least one of a hydrocarbon and carbon monoxide. The elemental composition of the source gas can be adjusted according to the temperature at which the solid carbon capture catalyst 5 is heated, taking into account the relationship between the decomposition temperature of the hydrocarbon and the molar ratio of carbon atoms, hydrogen atoms, and oxygen atoms. Specifically, for example, at 400°C, the O / C ratio may be 0.2 to 2.0 and the H / C ratio may be 0 to 4.3; at 500°C, the O / C ratio may be 0.2 to 2.2 and the H / C ratio may be 0 to 4.7; at 600°C, the O / C ratio may be 0.3 to 2.1 and the H / C ratio may be 0 to 4.8; and at 700°C, the O / C ratio may be 0.3 to 1.9 and the H / C ratio may be 0 to 5.3. The hydrocarbon may contain methane. Hydrocarbons with two or more carbon atoms may be decomposed into methane before use.

[0027] The temperature to which the solid carbon capture catalyst 5 is heated to precipitate solid carbon may be, for example, 400°C or higher and 800°C or lower, 700°C or lower, 650°C or lower, 550°C or lower, 500°C or lower, or 490°C or lower; 430°C or higher and 800°C or lower, 700°C or lower, 650°C or lower, 550°C or lower, 500°C or lower, or 490°C or higher; or 450°C or higher and 800°C or lower, 700°C or lower, 650°C or lower, 550°C or lower, 500°C or lower, or 490°C or lower. The heating temperature may be constant or may vary during the reaction.

[0028] The solid carbon collector can also be combined with another reaction device that discharges a feed gas containing a carbon source such as hydrocarbons. FIG. 3 is a schematic diagram showing an example of a reaction system including a combination of a solid carbon collector and a reformer equipped with a reforming catalyst that produces carbon monoxide from a feed gas containing hydrocarbons. The reaction system 100 shown in FIG. 3 is mainly composed of a reformer 10 and a solid carbon collector 20 according to the above-described embodiment. That is, the reaction system 100 includes a catalyst set consisting of a combination of a reforming catalyst and a solid carbon collector catalyst. A piping 40 forms a flow path for gas to flow from the reformer 10 to the solid carbon collector 20. Downstream of the reformer 10, the piping 40 branches to form a flow path leading to the solid carbon collector 20 as well as a flow path for discharging gas without passing through the solid carbon collector 20. A valve 33 is provided on the branched piping 40.

[0029] The reformer 10 includes a reaction tube 11, a reforming catalyst 15 provided within the reaction tube 11, and a heater 12 provided around the reaction tube 11. The reforming catalyst may be, for example, a dry reforming catalyst that produces carbon monoxide and hydrogen from hydrocarbons and carbon dioxide, or a steam reforming catalyst that produces carbon monoxide, carbon dioxide, and hydrogen from hydrocarbons and water. The reforming catalyst 15 can be heated by the heater 12. The reforming catalyst 15 includes a tubular substrate and a reforming catalytic active component (e.g., a dry reforming catalytic active component or a steam reforming catalytic active component) disposed on the substrate. The substrate may have honeycomb-structured fins housed inside the tubular substrate, and a catalytic active layer containing the reforming catalytic active component may be formed on the surface of the fin. The catalytic active layer may include, for example, a porous support containing alumina and the reforming catalytic active component supported on the porous support. The reforming catalytically active component may be, for example, nickel, cobalt, molybdenum, rhodium, ruthenium, aluminum, zirconium, magnesium, or an oxide thereof, or may be nickel, cobalt, molybdenum, rhodium, aluminum, or an oxide thereof. These reforming catalytically active components can function as catalysts for the dry reforming reaction or the steam reforming reaction described below. Other examples of reforming catalytically active components for the steam reforming reaction include palladium, zinc, potassium, and calcium. The reforming catalyst 15 may be a granular material containing the reforming catalytically active component.

[0030] When the reforming catalyst 15 is a dry reforming catalyst, if a raw material gas G1 containing hydrocarbons and carbon dioxide is supplied to the reaction system 100 while the reforming catalyst 15 (or reforming catalyst active component) and the solid carbon capture catalyst 5 are heated, carbon monoxide and hydrogen are produced by the following dry reforming reaction in the reforming catalyst 15. When the reforming catalyst 15 is a steam reforming catalyst, if a raw material gas G1 containing hydrocarbons and water (steam) is supplied to the reaction system 100 while the reforming catalyst 15 (or reforming catalyst active component) and the solid carbon capture catalyst 5 are heated, carbon monoxide and hydrogen are produced by the following steam reforming reaction in the reforming catalyst 15. Before the raw material gas G1 is supplied, the reforming catalyst 15 may be reduced with hydrogen gas or the like. CH4 + CO2 → 2CO + 2H2 (dry reforming reaction) Methane + water → carbon dioxide + carbon monoxide + hydrogen (steam reforming reaction)

[0031] The raw material gas discharged from the reformer 10 contains carbon monoxide and hydrogen in addition to hydrocarbons. When this raw material gas flows into the solid carbon collector 20, it is believed that the decomposition reaction of hydrocarbons (e.g., methane) as well as the Boudoard reaction, which produces solid carbon from carbon monoxide, proceeds, resulting in efficient deposition of solid carbon. CH4 → C + 2H2 (solid carbonization reaction, methane decomposition reaction) 2CO → C + CO2 (solid carbonization reaction, Boudouard reaction) When solid carbon is captured mainly by the Boudouard reaction, the proportion of water in the exhaust gas G2 is small.

[0032] The heating temperature of the reforming catalyst 15 (or the reforming catalytic active component) may be, for example, 500 to 900°C.

[0033] The reaction system 100 can also be used to capture solid carbon and produce a gas containing hydrogen. In particular, if the reforming catalyst 15 is a steam reforming catalyst, a gas (exhaust gas G2) containing a high proportion of hydrogen can be produced efficiently. In recent years, hydrogen has been attracting attention as a next-generation energy source, and its usage has tended to increase. Conventionally, 15 billion m3 of hydrogen has been produced using steam reforming. 3 of hydrogen is currently being supplied, but in the future, 22 billion m 3 Another method of hydrogen supply, known as water electrolysis, currently has a capacity of 2,000 m 3 / h is the limit. With steam reforming, it is desirable to further increase the proportion of hydrogen and reduce the carbon dioxide emissions. Combining a reformer containing a steam reforming catalyst with a solid carbon capture device makes it possible to increase the proportion of hydrogen and reduce the proportion of carbon dioxide in the exhaust gas.

[0034] When the reforming catalyst 15 is a steam reforming catalyst, the reaction system 100 may have a moisture remover 50 provided on the flow path (piping 40) connecting the reformer 10 and the solid carbon collector 20, as in another example shown in Figure 4. By providing the moisture remover 50, the amount of moisture in the gas flowing into the solid carbon collector 20 is reduced, thereby enabling further improvements in terms of increasing the amount of solid carbon captured, reducing carbon dioxide emissions, and increasing the proportion of hydrogen gas in the exhaust gas G2.

[0035] The raw material gas G1 supplied to the reformer 10 may be a gas containing methane produced by the methanation reaction of CO2 described below. For this purpose, the reaction system 100 may further include a methanation reaction device provided upstream of the reformer 10. CO2 + 4H2 → CH4 + 2H2O (methanation reaction) [Example]

[0036] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0037] -Consideration 1- 1. Reaction System Preparation 1-1. Catalyst for dry reforming 80 mL of water in a beaker was heated to 55°C, and 12 g of aluminum triipropoxide was added. The reaction solution in the beaker was stirred for 5 minutes, allowed to stand for 20 minutes, and then 6 mL of nitric acid and 4 mL of formaldehyde were added sequentially. The reaction solution was stirred for several minutes and then allowed to stand. Next, the reaction solution was stirred for several minutes every 20 minutes, and 100 minutes after the addition of formaldehyde, the reaction solution was cooled to room temperature. The reaction solution was left at room temperature for two days to form an aluminum sol.

[0038] A stainless steel pipe (made of ferritic stainless steel, diameter: 20 mm, length: 60 mm) containing honeycomb-structured fins (made of ferritic stainless steel) was prepared as a substrate for catalyst formation. This substrate was activated by sequentially immersing it in an aqueous sodium hydroxide solution and then in an aqueous hydrochloric acid solution. The activated substrate was then immersed in aluminum sol. The substrate was removed from the aluminum sol and rotated on a turntable to ensure that the aluminum sol attached to the substrate had a uniform thickness. The substrate with the aluminum sol attached was then fired in a muffle furnace to form a porous alumina body on the surface of the substrate. The same procedure was repeated three times.

[0039] The substrate with the porous alumina body formed thereon was alternately immersed in a Sn bath and a Pd bath to form Pd nuclei within the porous alumina body. Ni was then deposited on the Pd nuclei by electroless plating to obtain a dry reforming catalyst having a catalytically active layer containing the porous alumina body and metallic nickel supported on the porous alumina body.

[0040] 1-2. Catalyst for solid carbon capture (Fe3O4) Iron oxide (Fe3O4) was finely ground and suspended in propanol. A hollow stainless steel tube (ferritic stainless steel, diameter: 20 mm, length: 20-50 mm) was immersed in the resulting suspension. The stainless steel tube was removed from the suspension, and the suspension adhering to the stainless steel tube was dried by heating at 60-100°C, forming a porous coating layer (thickness: 10-2000 μm) containing Fe3O4 on the inner wall surface of the stainless steel tube. One to five stainless steel tubes with similar coating layers were prepared as catalysts for solid carbon capture.

[0041] 2-1. Catalytic reaction test (1) Example 1 The prepared dry reforming catalyst and solid carbon capture catalyst were placed in the reaction tube of a reaction system equipped with a reformer and a solid carbon capture device, similar to the configuration shown in Figure 3. One to five carbon capture catalysts were arranged in series within the reaction tube. A CO2 cylinder, CH4 cylinder, N2 cylinder, and H2 cylinder were connected to the piping supplying the raw gas. To perform hydrogen reduction of the catalyst, valves 31 and 32 were opened, valve 33 was closed, and the temperature of the dry reforming catalyst and solid carbon capture catalyst was maintained at 600°C for 2 hours while hydrogen gas was flowing. Next, valves 31 and 32 on the piping on the solid carbon capture device side were closed, valve 33 was opened, and the dry reforming catalyst was heated to 700°C while a raw gas containing CH4 and CO2 was flowed into the reaction tube of the dry reformer for 1 hour, performing only the dry reforming reaction (DRM) of methane. The CH4 flow rate was 0.75 x 10 -3 The composition of the feed gas was adjusted so that the CO2 / CH4 (mol / min) molar ratio was 1.2. Next, valves 31 and 32 on the piping on the solid carbon capture device side were opened, and valve 33 was closed. The feed gas was then passed through the dry reforming reaction tube and the carbon capture reaction tube for 8 hours. During this time, the temperature of the carbon capture catalyst was lowered from 650°C to 600°C over 2 hours, and then increased from 600°C to 650°C over 2 hours. This process was repeated twice. The valve on the piping on the solid carbon capture catalyst side was then closed, and the feed gas was passed through only the dry reforming reaction tube for 1 hour. During this process, the composition of the exhaust gas was analyzed using a TCD gas chromatograph (GC-8A, Shimadzu Corporation). Figure 5 shows the relationship between the conversion rates of CH4 and CO2 and the H2 / CO (molar ratio) versus time in the examples. When the carbon capture catalyst was removed from the reaction tube, a large amount of solid carbon was found to have deposited on the inside. The carbon capture efficiency was 15.5% of the total carbon amount from CH4 and CO2 in the feed gas.

[0042] (Comparative Example 1) A catalytic reaction test was carried out in the same manner as in the example, except that one to five stainless steel pipes (made of ferritic stainless steel, diameter: 20 mm, length: 20 to 50 mm) without a coating layer were used instead of the catalyst with a coating layer containing iron oxide. The carbon capture efficiency was 8.5% of the total carbon amount of CH4 and CO2 in the raw gas.

[0043] 2-2. Catalytic reaction test (2) Example 2 The carbon capture efficiency was measured under the same conditions as in Example 1, except that the temperature of the carbon capture catalyst was maintained at 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 550°C, 600°C, or 650°C for 8 hours while the raw material gas was flowing through the reaction tube for dry reforming and the reaction tube for carbon capture.

[0044] (Comparative Example 2) A catalytic reaction test was carried out in the same manner as in Example 2, except that a stainless steel pipe (made of ferritic stainless steel, diameter: 20 mm, length: 20-50 mm) without a coating layer was used instead of a catalyst with a coating layer containing iron oxide, and the temperature was maintained at 600°C for 8 hours.

[0045] (result) Figure 6 is a graph showing the carbon capture efficiency relative to the total carbon amount of CH4 and CO2 in the feed gas at each temperature. Figure 7 is a graph showing the relationship between the CH4 and CO2 conversion rate (conversion) and H2 / CO (molar ratio) and time when the temperature of the carbon capture catalyst is 450°C, and the relationship between the proportions of hydrogen, carbon dioxide, carbon monoxide, and methane in the exhaust gas and time. Figure 8 is a scanning electron microscope photograph of solid carbon deposited on a carbon capture catalyst containing Fe3O4.

[0046] - Study 2 - 1. Catalyst for solid carbon capture Fe2O3, FeO, cobalt oxide A solid carbon capture catalyst having a stainless steel tube and a porous coating layer containing these metal oxides on its inner wall surface was prepared in the same manner as in "1-2. Solid carbon capture catalyst (Fe3O4)", except that iron oxide (Fe2O3), iron oxide (FeO), or cobalt oxide (a mixture of CoO and Co3O4) was used instead of iron oxide (Fe3O4).

[0047] Fe / Al3O4 Alumina slurry was prepared by placing 3 g of high-purity alumina and 30 mL of distilled water in a side-arm flask and stirring the mixture for 5 hours while degassing. A 200 mL beaker was charged with iron nitrate nonahydrate (20.7 mg) and 30 mL of distilled water and stirring for 10 minutes to obtain an aqueous solution of iron nitrate. The alumina slurry was added to the aqueous solution of iron nitrate, and the mixture in the beaker was stirred for 2 hours. The mixture was then transferred to an evaporating dish and heated to 80°C. The water was evaporated while stirring the mixture with a fluororesin rod. The powder remaining in the evaporating dish was calcined in a flow-through calciner at 600°C for 3 hours while air was flowing, yielding a catalyst (Fe / Al2O3) in which metallic iron was supported on an alumina support.

[0048] A slurry containing Fe / Al2O3 was prepared by placing 6 g of Fe / Al2O3 and 40 mL of 2-propanol in a polypropylene bottle. A pre-weighed stainless steel hollow tube (2.0 cm outer diameter, 1.8 cm inner diameter, 2.5 cm length) was immersed in the resulting slurry for 5 seconds. The hollow tube was removed from the slurry and dried in a hair dryer. The remaining Fe / Al2O3 on the outer wall was wiped off with a paper wipe to obtain a solid carbon capture catalyst with a coating layer containing Fe / Al2O3 on the inner wall of the hollow tube. The resulting solid carbon capture catalyst was reweighed, and the net mass of Fe / Al2O3 (mass of the coating layer) was calculated by subtracting the mass of the hollow tube before immersion in the slurry from this value. Immersion in the slurry and drying were repeated until the mass of the Fe / Al2O3 reached 50 mg.

[0049] 2. Catalytic reaction test The carbon capture efficiency was measured under the same conditions as in Example 1, except that the prepared solid carbon capture catalyst was used and the temperature of the carbon capture catalyst was maintained at a predetermined temperature for 8 hours while the feed gas was flowing through the dry reforming reaction tube and the carbon capture reaction tube. In the case of iron oxide (Fe2O3), the temperature of the carbon capture catalyst was maintained at 450°C, and the carbon capture efficiency was 20.3% of the total carbon amount of CH4 and CO2 in the feed gas. In the case of iron oxide (FeO), the temperature of the carbon capture catalyst was maintained at 600°C, and the carbon capture efficiency was 15.0% of the total carbon amount of CH4 and CO2 in the feed gas. In the case of cobalt oxide, the temperature of the carbon capture catalyst was maintained at 500°C, and the carbon capture efficiency was 10.2% of the total carbon amount of CH4 and CO2 in the feed gas. The compositions of exhaust gases from carbon capture catalysts containing iron(III) oxide (FeO) and Fe / AlO were analyzed using a TCD gas chromatograph (GC-8A, Shimadzu Corporation). In the case of Fe / AlO, the temperature of the carbon capture catalyst was maintained at 500°C, and the carbon capture efficiency was 16.0% of the total carbon content of CH and CO in the feed gas. Figure 9 shows the relationship between the conversion rate of CH and CO and the H / CO molar ratio versus time when the carbon capture catalyst contains iron oxide (FeO). Figure 10 shows the relationship between the conversion rate of CH and CO and the H / CO molar ratio versus time when the carbon capture catalyst contains Fe / AlO. Figure 11 is a graph showing the ratio of hydrogen, carbon dioxide, carbon monoxide, and methane in exhaust gases versus time when the carbon capture catalyst contains Fe / Al2O3, and Figure 12 is a scanning electron micrograph of solid carbon deposited on a carbon capture catalyst containing Fe / Al2O3.

[0050] - Study 3 - Catalytic reaction test (steam reforming) In the same reaction system as in Example 1, an HPLC pump for supplying water, a CH4 cylinder, an N2 cylinder, and an H2 cylinder were connected to the pipe supplying the raw material gas. To perform hydrogen reduction treatment of the catalyst, valves 31 and 32 were opened, valve 33 was closed, and hydrogen gas was allowed to flow. The temperatures of the reforming catalyst and the solid carbon capture catalyst were maintained at 600°C for 2 hours. Subsequently, valves 31 and 32 on the pipe on the solid carbon capture device side were closed, valve 33 was opened, and the reforming catalyst was heated to 700°C. A raw material gas containing CH4 and HO was allowed to flow through the reformer reaction tube for 1 hour, performing only the steam reforming reaction (SRM) of methane. CH 4、 The flow rate of H2O is 2.5 × 10 -3 The composition of the feed gas was adjusted so that the CO2 / CH4 molar ratio was 1.0 (mol / min). Next, valves 31 and 32 on the piping on the solid carbon capture device side were opened, and valve 33 was closed, allowing the feed gas to flow through the reforming reaction tube and the carbon capture reaction tube for 8 hours. During this time, the temperature of the carbon capture catalyst was maintained at 650°C. Then, the valve on the piping on the solid carbon capture catalyst side was closed, and the feed gas was allowed to flow only through the reforming reaction tube for 1 hour. During this process, the composition of the exhaust gas was analyzed using a TCD gas chromatograph (GC-8A, Shimadzu Corporation). Figure 13 is a graph showing the relationship between the conversion rate of CH4 and CO2 and the H2 / CO (molar ratio) versus time, and the relationship between the amounts of hydrogen, carbon dioxide, methane, and carbon monoxide in the exhaust gas versus time. The carbon capture rate was 18.0% of the total carbon content of CH4 and CO2 in the feed gas. An exhaust gas containing a high proportion of hydrogen was produced. [Explanation of symbols]

[0051] 1...substrate, 3...coating layer, 5...solid carbon capture catalyst, 10...reforming device, 11...reaction tube, 12...heater, 15...reforming catalyst, 20...solid carbon capture device, 21...reaction tube, 22...heater, 40...piping, 50...moisture removal device, 100...reaction system, G1...raw material gas, G2...exhaust gas

Claims

1. a reforming device including a reaction tube and a reforming catalyst provided in the reaction tube for producing carbon monoxide from a raw material gas containing hydrocarbon; a solid carbon capture device including a reaction tube and a solid carbon capture catalyst provided in the reaction tube; a flow path for flowing gas from the reformer to the solid carbon capture device; Equipped with the solid carbon capture catalyst has a substrate and a coating layer formed on a surface of the substrate; the coating layer contains at least one metal-containing component selected from the group consisting of iron oxide, cobalt oxide, magnesium oxide, molybdenum oxide, nickel oxide, manganese oxide, metallic iron, metallic cobalt, metallic magnesium, metallic molybdenum, metallic nickel, and metallic manganese; The coating layer is porous. Reaction system.

2. 2. The reaction system of claim 1, wherein the substrate is a tubular body, a planar body, or a spiral body.

3. 2. The reaction system according to claim 1, wherein the substrate is a tubular body, and the coating layer is formed on the inner wall surface of the tubular body.

4. 4. The reaction system of claim 3, wherein the tubular body is a stainless steel tube.

5. The coating layer is Fe ３ O ４ The reaction system according to any one of claims 1 to 4, comprising:

6. 6. The reaction system according to claim 1, wherein the reforming catalyst is a dry reforming catalyst that produces carbon monoxide and hydrogen from a feed gas containing hydrocarbons and carbon dioxide.

7. 6. The reaction system according to claim 1, wherein the reforming catalyst is a steam reforming catalyst that produces carbon monoxide, carbon dioxide, and hydrogen from a feed gas containing hydrocarbons and water.

8. the reforming catalyst has a substrate and a catalytically active layer formed on a surface of the substrate, The reaction system according to any one of claims 1 to 7, wherein the catalytically active layer contains at least one metal selected from the group consisting of nickel, cobalt, molybdenum, rhodium, ruthenium, aluminum, zirconium, and magnesium, or at least one oxide thereof.

9. CO ２ The reaction system according to any one of claims 1 to 8, which is used to capture solid carbon from a gas containing methane produced by the methanation reaction of

10. 10. A method for capturing solid carbon, comprising: supplying a feed gas containing hydrocarbons to the reaction system according to any one of claims 1 to 9 while heating the reforming catalyst and the solid carbon capture catalyst, thereby depositing solid carbon on the solid carbon capture catalyst.

11. The method is ２ and producing methane by the methanation reaction of the feed gas containing methane is supplied to the reaction system; The method of claim 10.

12. capturing solid carbon by the method of claim 10 or 11; Discharging an exhaust gas containing hydrogen from the solid carbon capture device; A method for producing a gas containing hydrogen, comprising:

13. A substrate and a coating layer formed on a surface of the substrate, the coating layer contains at least one metal-containing component selected from the group consisting of iron oxide, cobalt oxide, magnesium oxide, molybdenum oxide, nickel oxide, manganese oxide, metallic iron, metallic cobalt, metallic magnesium, metallic molybdenum, metallic nickel, and metallic manganese; the coating layer is porous; A solid carbon capture catalyst for use in combination with a reforming catalyst for producing carbon monoxide from a hydrocarbon-containing feed gas.

Images