Absorption-conversion catalyst and method for producing hydrocarbon compound

Abstract

To provide an absorption-conversion catalyst by which CO2 is converted into a hydrocarbon compound, the absorption-conversion catalyst exhibiting high durability even in an oxygen-containing atmosphere.SOLUTION: Provided is an absorption-conversion catalyst, comprising: a carrier; nickel element supported on the carrier; calcium element supported on the carrier; and at least one element A, supported on the carrier, the element A being selected from the group consisting of alkaline earth metals other than alkali metals and calcium, wherein, when X1 (mmol / g) is defined as the supported amount of the calcium element in the absorption-conversion catalyst and X2 (mmol / g) is defined as the supported amount of the element A in the absorption-conversion catalyst, the X1 and X2 satisfy formula (1-1) below. 0.02≤X1 / (X1+X2)≤0.95 (1-1).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an absorption conversion catalyst and a method for producing hydrocarbon compounds. [Background technology]

[0002] Carbon recycling has been studied to absorb and methane CO2, which is generated in large quantities from power plants, steelworks, chemical industries, etc. Existing methods involve a two-stage process in which low-concentration CO2 contained in exhaust gas is separated and captured using amine absorption or membrane separation to increase the concentration, and then hydrocarbons are synthesized through catalytic reactions of the CO2 obtained from this increased concentration.

[0003] Furthermore, as an example of a methanation catalyst that absorbs and converts CO2, Patent Document 1 discloses an absorption / conversion catalyst that includes an alumina oxide support, and a predetermined first component and a predetermined second component supported on the oxide support. Here, sodium, potassium or calcium is used as the first component, which is a carbon dioxide storage component, and nickel is used as the second component, which is a hydrocarbonation catalyst component.

[0004] Furthermore, Non-Patent Document 1 investigates the aging of an absorption / conversion catalyst called DFM (Dual Function Material), which performs CO2 absorption and conversion similarly to Patent Document 1. For Ru-DFM, which uses Ru as the hydrocarbonation component, three types of catalysts have been investigated: those in which only Na (4Ru-16Na), a mixture of Na and Ca (4Ru-8Na / 8Ca), and only Ca (4Ru-16Ca) are supported on alumina (Al2O3) as the carbon dioxide storage component.For Ni-DFM, which uses Ni as the main hydrocarbonation component, two types of catalysts have been investigated: those in which only Ni (10Ni-16Na) and a mixture of Ni and Ru (1Ru / 10Ni-16Na) are supported on alumina, with Na as the carbon dioxide storage component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2022 / 030203 [Patent Document 2] International Publication No. 2023 / 037652 [Non-patent literature]

[0006] [Non-Patent Document 1] Alejandro Bermejo-Lopez, et al., “Aging studies on dual function materials Ru / Ni-Na / Ca-Al2O3 for CO2 adsorption and hydrogenation to CH4”, Journal of Environmental Chemical Engineering, Volume 10, Issue 3, June 2022, 107951 Summary of the Invention [Problem to be solved by the invention]

[0007] In Non-Patent Document 1, a comparison is made of the amount of methane produced when a target catalyst is reduced (heated in a hydrogen / argon atmosphere) (reduced) and when a target catalyst is aged (heated in a steam / oxygen / argon atmosphere) (aged). The reduced catalyst is used as the standard, and the aged catalyst reported that the methane production of the treated catalysts decreased by up to 25% for Ru-DFM and up to 60% for Ni-DFM (see Non-Patent Document 1, Figs. 7 and 9). When subjected to deactivation, the Ni-DFM with the composition investigated in this paper showed a significantly greater decrease in methane production than Ru-DFM.

[0008] The present disclosure provides an absorption conversion catalyst for converting CO2 into hydrocarbon compounds, which is used in an oxygen-containing atmosphere. The present disclosure also provides an absorption conversion catalyst that is highly durable under atmospheric conditions. The present disclosure also provides a method for producing hydrocarbon compounds that can efficiently produce hydrocarbon compounds. [Means for solving the problem]

[0009] The present disclosure provides: A carrier; nickel element supported on the support; Calcium element supported on the carrier; and one or more elements A selected from the group consisting of alkali metals and alkaline earth metals excluding calcium, supported on the support, The present invention relates to an absorption conversion catalyst in which, when the amount of the calcium element supported in the absorption conversion catalyst is X1 (mmol / g) and the amount of the element A supported in the absorption conversion catalyst is X2 (mmol / g), X1 and X2 satisfy the following formula (1-1): 0.02≦X1 / (X1+X2)≦0.95 (1-1)

[0010] The present disclosure also provides: (a) providing an absorption conversion catalyst of the present disclosure; (b) contacting the absorption conversion catalyst with a gas containing carbon dioxide to cause the absorption conversion catalyst to occlude carbon dioxide; (c) contacting the carbon dioxide-occluded absorption conversion catalyst with a reducing gas to obtain a hydrocarbon compound; The present invention relates to a method for producing a hydrocarbon compound, comprising: [Effects of the Invention]

[0011] The present disclosure provides an absorption conversion catalyst that directly recovers CO2 without a separation process and converts it into hydrocarbon compounds, and that has high durability in an oxygen-containing atmosphere. The present disclosure also provides a method for producing hydrocarbon compounds that can efficiently produce hydrocarbon compounds. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 10 is an explanatory diagram showing the evaluation results of the examples. [Figure 2] FIG. 10 is an explanatory diagram showing the evaluation results of the examples. [Figure 3] FIG. 1 is a schematic diagram illustrating a portion of an integrated CO2 capture and conversion system employing fixed-bed reactions, according to one embodiment of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of an integrated CO2 capture and conversion system using a circulating fluidized bed reaction according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure will be described in detail below, but is not limited to the following description. Unless otherwise specified, the expressions "XX to YY" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0014] The present inventors speculate as follows about the reason why the performance of the absorption / conversion catalyst disclosed in Non-Patent Document 1 may deteriorate during repeated testing in an oxygen-containing atmosphere. That is, in an oxygen-containing atmosphere, the alkali metals and alkaline earth metals that are the carbon dioxide storage components tend to aggregate and reduce their reactivity due to heat generated by the oxidation reaction of hydrocarbonization catalyst components such as nickel and repeated absorption / conversion reactions. Possible factors that affect the aggregation of the carbon dioxide storage component include the heat generated during the absorption reaction and hydrogenation reaction and interactions with the carrier.

[0015] Based on this speculation, the present inventors have conducted extensive research into absorption conversion catalysts that are highly durable in oxygen-containing atmospheres, and have found that the absorption conversion catalyst of the present disclosure can solve the above-mentioned problems.

[0016] The following describes the embodiments.

[0017] <Absorption conversion catalyst> The present disclosure provides: A carrier; nickel element supported on the support; Calcium element supported on the carrier; and one or more elements A selected from the group consisting of alkali metals and alkaline earth metals excluding calcium, supported on the support, The present invention relates to an absorption conversion catalyst in which, when the amount of the calcium element supported in the absorption conversion catalyst is X1 (mmol / g) and the amount of the element A supported in the absorption conversion catalyst is X2 (mmol / g), X1 and X2 satisfy the following formula (1-1): 0.02≦X1 / (X1+X2)≦0.95 (1-1)

[0018] The absorption conversion catalyst is a catalyst capable of absorbing carbon dioxide under specific conditions and converting the carbon dioxide into hydrocarbon compounds using a reducing gas. The absorption conversion catalyst of the present disclosure is also suitable for use in an oxygen-containing atmosphere.

[0019] As described above, the absorption conversion catalyst includes a support. The support is not particularly limited as long as it is usable as a catalyst support, and examples thereof include oxide supports. Examples of oxide supports include one or more supports selected from the group consisting of alumina supports, silica supports, titania supports, zirconia supports, ceria supports, and magnesia supports. Among these, from the viewpoint of enhancing catalytic activity, one or more supports selected from the group consisting of zirconia supports, alumina supports, and silica supports are preferred, and zirconia supports are particularly preferred.

[0020] The absorption conversion catalyst contains calcium element supported on a carrier. The calcium element acts as a carbon dioxide storage component. That is, carbon dioxide is selectively stored by the carbon dioxide storage component, and hydrocarbon compounds can be produced from carbon dioxide by reacting the stored carbon dioxide with a reducing gas in the presence of a hydrocarbonization catalyst component described below. Calcium element is known to exhibit excellent carbon dioxide storage capacity, particularly in high temperature ranges. This fact is consistent with the experimental results we have obtained. Here, examples of the manner in which the carbon dioxide storage component occludes carbon dioxide include a manner in which carbon dioxide molecules are adsorbed onto the carbon dioxide storage component, and a manner in which the carbon dioxide storage component forms a carbonate (more specifically, a manner in which calcium carbonate is formed).

[0021] The form in which the absorption conversion catalyst contains calcium element is not particularly limited, and examples thereof include calcium oxide, hydroxide, carbonate, etc. That is, the absorption conversion catalyst may contain one or more compounds selected from the group consisting of calcium oxide, calcium hydroxide, and calcium carbonate supported on a carrier.

[0022] The absorption conversion catalyst contains one or more elements A selected from the group consisting of alkali metals and alkaline earth metals excluding calcium, supported on a carrier. The element A acts as a carbon dioxide storage component. The element A is an element different from calcium. In other words, two or more types of carbon dioxide storage components are used in combination. This improves durability in an oxygen-containing atmosphere. By using two or more types of carbon dioxide storage components in combination, durability in an oxygen-containing atmosphere is improved. Although the reason for the improved durability in the carbon dioxide absorption catalyst is unclear, the inventors speculate as follows: When an absorption / conversion catalyst contains only calcium element as a carbon dioxide storage component, in an oxygen-containing atmosphere, repeated absorption and reduction reactions and heat generation accompanying the oxidation reaction of nickel metal, etc., cause the calcium element to move on the carrier in search of a stable state. This can cause the calcium element to aggregate. Aggregation of calcium element reduces the carbon dioxide absorption performance. On the other hand, by adding element A, which acts as a carbon dioxide storage component and is different from calcium element, it is thought that element A can suppress the aggregation of calcium element due to steric effects such as steric hindrance of element A.

[0023] The element A is not particularly limited as long as it is one or more elements selected from the group consisting of alkali metals and alkaline earth metals excluding calcium. Element A is preferably one or more elements selected from the group consisting of lithium, sodium, potassium, rubidium, magnesium, strontium, and barium, more preferably one or more elements selected from the group consisting of lithium, sodium, potassium, and magnesium, even more preferably one or more elements selected from the group consisting of sodium and potassium, and particularly preferably sodium. When element A is one or more elements selected from the group consisting of sodium and potassium, catalytic activity is more likely to be improved. The reason for this is not clear, but the inventors speculate as follows. That is, it is thought that this is because sodium and potassium, which are alkali metals, exhibit excellent effects as carbon dioxide storage components and have little interaction with calcium, which is an alkaline earth metal, and can exist on the catalyst in an independent state.

[0024] When the amount of calcium element supported in the absorption conversion catalyst is X1 (mmol / g) and the amount of element A supported in the absorption conversion catalyst is X2 (mmol / g), X1 and X2 satisfy the following formula (1-1). 0.02≦X1 / (X1+X2)≦0.95 (1-1) X1 / (X1+X2) represents the molar ratio of the amount of calcium supported to the amounts of element A and calcium supported in the absorption conversion catalyst. The fact that X1 and X2 satisfy the above formula (1-1) indicates that while calcium is the primary contributor, calcium and element A must each be present in a certain proportion on the support. In other words, neither calcium nor element A plays a supporting role, but each must be present in a certain proportion. The complementary effects achieved by these two elements result in an excellent absorption conversion catalyst. This results in improved durability in oxygen-containing environments. The amount of calcium supported in the absorption conversion catalyst (mmol / g) represents the amount of calcium (mmol) per gram of absorption conversion catalyst. The same applies to element A.

[0025] In particular, since the complementary effect presumably due to the promotion of the diffusion of carbon dioxide occluded in the compound derived from calcium element or element A is more easily exerted, it is more preferable that X1 and X2 satisfy the following formula (1-2), (1-3), (1-4), (1-5) or (1-6). 0.20≦X1 / (X1+X2)≦0.95 (1-2) 0.35≦X1 / (X1+X2)≦0.95 (1-3) 0.55≦X1 / (X1+X2)≦0.89 (1-4) 0.65≦X1 / (X1+X2)≦0.86 (1-5) 0.80≦X1 / (X1+X2)≦0.84 (1-6)

[0026] X1 is not particularly limited as long as it satisfies the formula (1-1), but is preferably 0.15 to 3.00 mmol / g, more preferably 0.50 to 2.60 mmol / g, even more preferably 1.00 to 2.60 mmol / g, and particularly preferably 1.50 to 2.60 mmol / g. A range of 0.00 to 2.60 mmol / g is particularly preferred. Furthermore, X2 is not particularly limited as long as it satisfies formula (1-1), but is preferably 0.30 to 4.20 mmol / g, more preferably 0.40 to 2.50 mmol / g, even more preferably 0.40 to 2.00 mmol / g, particularly preferably 0.40 to 1.30 mmol / g, and particularly preferably 0.40 to 1.00 mmol / g. X1 and X2 are measured using inductively coupled plasma optical emission spectroscopy (ICP-OES). Specifically, the measurement procedure is as follows. Weigh out 1g of the absorption conversion catalyst, dissolve it in hydrochloric acid and hydrofluoric acid, then add ultrapure water to obtain a test solution. After that, quantitative analysis of each element in the test solution is performed using ICP-OES.

[0027] The absorption conversion catalyst contains nickel element supported on a carrier. The nickel element functions as a hydrocarbonation catalyst component. By including the hydrocarbonation catalyst component and the carbon dioxide storage component, the absorption conversion catalyst becomes capable of reacting the carbon dioxide stored in the carbon dioxide storage component with a reducing gas. Ru is a well-known material as a hydrocarbon conversion catalyst component in absorption conversion catalysts. However, Ru, classified as a precious metal, is more than 100 times more expensive than Ni, so using Ni while also improving the durability of the absorption conversion catalyst offers significant cost advantages. The form in which the absorption conversion catalyst contains nickel element is not particularly limited, and examples thereof include nickel oxide, hydroxide, nitrate, carbonate, and the like.

[0028] The nickel content in the absorption conversion catalyst is not particularly limited, but is preferably 25% by weight or less, more preferably 15% by weight or less, and even more preferably 10% by weight or less. The lower limit is not particularly limited, but examples include 1 to 25% by weight, 1 to 15% by weight, and 1 to 10% by weight. The nickel content in the absorption conversion catalyst can be measured by XRF (X-ray fluorescence analysis).

[0029] As described above, the absorption conversion catalyst of the present disclosure can function as an absorption conversion catalyst even in an embodiment that does not contain a precious metal. Therefore, it is preferable that the absorption conversion catalyst does not contain a precious metal. Examples of precious metals include gold, silver, platinum, palladium, rhodium, iridium, ruthenium, and osmium. In another preferred embodiment, the absorption conversion catalyst essentially consists of the above-mentioned carrier, nickel element supported on the carrier, calcium element supported on the carrier, and one or more elements A selected from the group consisting of alkali metals and alkaline earth metals excluding calcium, supported on the carrier, and when the amount of calcium element supported in the absorption conversion catalyst is X1 (mmol / g) and the amount of element A supported in the absorption conversion catalyst is X2 (mmol / g), X1 and X2 satisfy the above formula (1-1). Here, "consisting essentially of only" means that in addition to nickel, calcium, and element A, trace amounts of other elements that do not affect the fundamental and novel properties of the absorption conversion catalyst are permitted to be mixed in as impurities (for example, 10 mol % or less based on the total amount of elements contained in the absorption conversion catalyst).

[0030] <Method of producing hydrocarbon compounds> The present disclosure provides a process for producing an absorption conversion catalyst comprising: (a) providing an absorption conversion catalyst of the present disclosure; (b) contacting the absorption conversion catalyst with a gas containing carbon dioxide to cause the absorption conversion catalyst to occlude carbon dioxide; (c) contacting the carbon dioxide-occluded absorption conversion catalyst with a reducing gas to obtain a hydrocarbon compound; The present invention relates to a method for producing a hydrocarbon compound, comprising:

[0031] In step (a), the absorption conversion catalyst of the present disclosure is prepared. The step of preparing the absorption conversion catalyst is not particularly limited, and the catalyst can be produced based on a known method for producing an absorption conversion catalyst. For example, the catalyst can be produced based on the production method described in the Examples of this specification.

[0032] In step (b), the absorption conversion catalyst is contacted with a gas containing carbon dioxide to allow the absorption conversion catalyst to occlude carbon dioxide. The manner of contact is not particularly limited, and for example, the absorption conversion catalyst may be contacted with the gas containing carbon dioxide under reduced pressure. Furthermore, in the production method of this embodiment, the reaction is carried out under a pressure higher than atmospheric pressure, thereby improving the carbon dioxide occlusion performance of the absorption conversion catalyst and the carbon dioxide hydrocarbonization performance of the absorption conversion catalyst.

[0033] The temperature of the atmosphere in which carbon dioxide is absorbed into the absorption conversion catalyst can be appropriately adjusted by the atmospheric pressure, etc., but is preferably room temperature to 600°C from the viewpoint of suppressing condensation of water on the catalyst and oxidation of the hydrocarbonation catalyst components. The time for which the absorption conversion catalyst is allowed to absorb carbon dioxide can be adjusted appropriately depending on the atmospheric pressure, temperature, carbon dioxide concentration, etc.

[0034] In the production method of this embodiment, the carbon dioxide concentration in the carbon dioxide-containing gas used as a raw material is not particularly limited. The carbon dioxide concentration in the carbon dioxide-containing gas used as a raw material may be, for example, 0.001 to 20% by volume, preferably 0.01 to 15% by volume, more preferably 0.03 to 13% by volume, even more preferably 0.04 to 11% by volume, and particularly preferably 0.1 to 11% by volume.

[0035] The carbon dioxide-containing gas may contain other gases. For example, it may contain water vapor gas or oxygen gas. In particular, when oxygen gas is contained, the durability of the absorption conversion catalyst may be significantly reduced as described in the "Problem to be Solved by the Invention" section. However, the absorption conversion catalyst of the present disclosure has high durability even in an oxygen-containing atmosphere. As a result, hydrocarbon compounds can be efficiently produced even when a gas containing carbon dioxide and oxygen, such as factory exhaust gas, is used as a raw material gas. When the carbon dioxide-containing gas contains oxygen gas, the content of oxygen gas in the carbon dioxide-containing gas may be 1 to 20% by volume, or may be 1 to 5% by volume. The absorption conversion catalyst of the present disclosure can function favorably as an absorption conversion catalyst even in an atmosphere containing oxygen gas at such a content.

[0036] The reducing gas is not particularly limited as long as it can reduce carbon dioxide and convert it into a hydrocarbon compound, but pure hydrogen gas and hydrogen-containing gas are preferred. Hydrogen gas obtained by water electrolysis using an energy-saving power generation system can also be used as the reducing gas. Other gases that can be contained in the reducing gas are not particularly limited as long as they do not inhibit the carbon dioxide reduction reaction, but inert gases such as helium gas and nitrogen gas are preferred. From the viewpoint of reduction efficiency, the hydrogen concentration in the hydrogen-containing gas is preferably 5% by volume or more, more preferably 10% by volume or more. There are no particular upper limits, and it can be, for example, 5 to 100% by volume, 10 to 100% by volume, 20 to 98% by volume, or 50 to 98% by volume.

[0037] In step (c), a reducing gas is brought into contact with the absorption conversion catalyst in which carbon dioxide has been occluded, to obtain a hydrocarbon compound. The temperature of the atmosphere in which the occluded carbon dioxide and the reducing gas are reacted can be adjusted as appropriate by the pressure of the atmosphere, etc., but from the viewpoint of improving the hydrocarbon compound production rate and suppressing carbon dioxide desorption during reduction, thereby obtaining high hydrocarbon compound production efficiency, the temperature is preferably 150 to 700°C, and more preferably 300 to 500°C. The reaction time between the absorbed carbon dioxide and the reducing gas depends on the atmospheric pressure, temperature, This can be adjusted appropriately by adjusting the carbon dioxide concentration, etc.

[0038] (hydrocarbon compounds) The hydrocarbon compound obtained in step (c) is not particularly limited and includes hydrocarbons having 1 to 5 carbon atoms (methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, ethylene, propylene, etc.), with methane and ethane being preferred, and methane being more preferred. In addition to hydrocarbon compounds, the compound obtained in step (c) may also include carbon monoxide (CO), alcohols (methanol, ethanol, etc.), etc. In the production method of this embodiment, the synthesis ratios of hydrocarbon compounds, carbon monoxide (CO), and alcohols can be adjusted by adjusting the conditions in the production method based on the examples and common methods described below.

[0039] In the above production method, step (c) is preferably carried out after step (b). Examples of step (c) carried out after step (b) include a step in which step (c) is carried out temporally after step (b) has ended, and a step in which step (c) is carried out in a space different from step (b). The above production method may be carried out using, for example, a fixed-bed reactor or a circulating fluidized-bed reactor as described in Patent Document 2. These reactors will be described in detail below. In step (b), a gas containing carbon dioxide is supplied to a reactor holding an absorption conversion catalyst, but the supply of the gas containing carbon dioxide is stopped when proceeding to step (c). Thereafter, in step (c), a reducing gas is supplied to the absorption conversion catalyst that has occluded carbon dioxide and is held in the reactor.

[0040] <Apparatus for carrying out the manufacturing method of the embodiment> Another aspect of the embodiment relates to an apparatus for carrying out the production method of the embodiment, the apparatus being a fixed-bed reactor including a carbon dioxide recovery and hydrocarbon compound synthesis reaction layer (hereinafter also referred to as a recovery reaction layer). By using a fixed bed, the catalyst can be easily recovered, and the above-described embodiment of the method can be carried out at low cost.

[0041] A part of the device of this embodiment is shown in FIG. FIG. 3 shows a part of a fixed-bed reactor, which shows the capture and reaction bed 301. In the capture and reaction bed 301, a carbon dioxide-containing gas is brought into contact with an absorption / conversion catalyst, causing the absorption / conversion catalyst to occlude the carbon dioxide. The carbon dioxide-occluded absorption / conversion catalyst is then brought into contact with a reducing gas to synthesize hydrocarbon compounds. In other words, using one capture and reaction bed 301, CO2 capture and conversion can be performed sequentially. It is also possible to provide two or more capture and reaction beds 301, and configure the device so that the supply of the carbon dioxide-containing gas and the reducing gas are switched complementarily at regular intervals. In this case, CO2 capture and conversion can be performed continuously by switching between at least two capture and reaction beds 301. 3 indicates alkali metals and alkaline earth metals, and calcium element and element A. Also, the bifunctional catalyst in FIG. 3 indicates an absorption conversion catalyst.

[0042] Another aspect of the embodiment relates to an apparatus for carrying out the production method of the embodiment, the apparatus being a circulating fluidized bed reactor including a carbon dioxide capture layer, a hydrocarbon compound synthesis reaction layer, and a catalyst circulation path connecting the carbon dioxide capture layer and the hydrocarbon compound synthesis reaction layer. The use of a circulating fluidized bed allows the catalytic reaction for CO2 capture and conversion to proceed continuously. Furthermore, by using a scaled-up circulating fluidized bed, the catalytic reaction can proceed at a large flow rate.

[0043] The device of this embodiment is shown in FIG. The circulating fluidized bed reactor 400 shown in Figure 4 includes a carbon dioxide capture layer 401 for contacting an absorption conversion catalyst with a gas containing carbon dioxide to occlude the carbon dioxide in the absorption conversion catalyst and capture the carbon dioxide; a hydrocarbon compound synthesis reaction layer 402 for synthesizing hydrocarbon compounds by contacting the absorption conversion catalyst that has occluded carbon dioxide with a reducing gas; and catalyst circulation paths 403a and 403b that connect the carbon dioxide capture layer and the hydrocarbon compound synthesis reaction layer and circulate the catalyst between the two layers. Here, the circulating fluidized bed 412 is composed of a fluidized medium, at least a portion of which is the absorption conversion catalyst. The flow direction in the circulating fluidized bed is the direction of arrow 418.

[0044] A first vent pipe 406a for blowing carbon dioxide-containing gas 404 into the container and a first compressor 405a for pressurizing the gas and venting it into the container are provided at the bottom of the container filled with the carbon dioxide capture layer. An inlet pipe 407 for introducing a catalyst into the container, which continues from the second catalyst circulation path, is provided at the top of the container. An exhaust pipe 408 for discharging gas from the container, a first back-pressure control valve 409a for depressurizing the gas and discharging it outside the container, and an exhaust pipe for discharging the catalyst from the container, which continues to the first catalyst circulation path, are provided on the side wall of the container. The gas discharged from the exhaust pipe 408 becomes CO2-free gas 411.

[0045] In the carbon dioxide capture layer 401, a gas 404 containing carbon dioxide is blown in through a first vent pipe 406a to raise a circulating fluidized bed 412 filled in a container. During this process, the circulating fluidized bed 412 is stirred and mixed, and carbon dioxide is occluded in the absorption conversion catalyst. Here, the absorption of carbon dioxide is an exothermic reaction.

[0046] The catalyst discharged from the vessel packed with the carbon dioxide capture layer is supplied to the hydrocarbon compound synthesis reaction layer through a first catalyst circulation path 403a connecting the carbon dioxide capture layer 401 and the hydrocarbon compound synthesis reaction layer 402. The first catalyst circulation path 403a is provided with a first gas replacement section 410a that brings the catalyst into contact with a first inert gas 413a such as nitrogen. In the first gas replacement section 410a, a first inert gas 413a such as nitrogen is supplied to fluidize the fluidized medium and prevent gas mixing between the carbon dioxide capture layer 401 and the hydrocarbon compound synthesis reaction layer 402.

[0047] A second vent pipe 406b for blowing a reducing gas such as hydrogen into the container and a second compressor 405b for pressurizing the gas and venting it into the container are provided at the bottom of the container filled with the hydrocarbon compound synthesis reaction layer. A discharge pipe leading to a second catalyst circulation path 403b for discharging the catalyst from the container is provided at the top of the container. An inlet pipe leading from the first catalyst circulation path 403a for introducing the catalyst into the container is provided at the side wall of the container.

[0048] In the hydrocarbon compound synthesis reaction layer 402, a gas 414 containing a reducing gas is blown in through the second vent pipe 406b to raise the circulating fluidized bed filled in the vessel. During this process, the circulating fluidized bed is stirred and mixed, and the carbon dioxide stored in the absorption conversion catalyst reacts with the reducing gas, synthesizing hydrocarbon compounds from the carbon dioxide. The release of the stored carbon dioxide here is an endothermic reaction and requires heating. On the other hand, the synthesis of hydrocarbon compounds from carbon dioxide and the reducing gas is an exothermic reaction. Therefore, in this process, the exothermic and endothermic reactions proceed simultaneously in the absorption conversion catalyst, completely or partially compensating for the heating required to release carbon dioxide, resulting in energy savings.

[0049] The catalyst discharged from the vessel filled with the hydrocarbon compound synthesis reaction layer passes through the second catalyst circulation path 403b and is supplied to the collection section 415 that collects the catalyst, etc. In the collection section 415, the generated gas and the catalyst are separated, and the generated gas is discharged from the discharge pipe, and the catalyst is returned to the second catalyst circulation path 403b. The gas passes through 403b and is returned to the carbon dioxide capture layer 401. The capture section 415 is provided with an exhaust pipe 416 for discharging the gas and a second back pressure control valve 409b for reducing the pressure of the gas before discharging it. The gas discharged from the exhaust pipe 416 becomes hydrocarbons 417. The second catalyst circulation path 403b is provided with a second gas replacement section 410b that brings the catalyst into contact with a second inert gas 413b such as nitrogen, thereby separating the gas atmosphere of the carbon dioxide recovery layer 401 from that of the hydrocarbon compound synthesis reaction layer 402. In the circulating fluidized bed reactor of FIG. 4, the carbon dioxide recovery layer and the hydrocarbon compound synthesis reaction layer are independent, which is advantageous when setting temperatures to optimize the respective reactions. [Example]

[0050] The present invention will be explained in more detail below with reference to examples, but is not limited to these examples as long as they do not depart from the gist of the invention.

[0051] Example 1 (Preparation of absorption conversion catalyst) An aqueous solution was prepared by dissolving 5.0 g of nickel nitrate hexahydrate (Kishida Chemical Co., Ltd., trade name: Special Grade Nickel (II) Nitrate (Hexahydrate)) in 250 mL of ion-exchanged water. Then, 10 g of zirconium oxide (Daiichi Kigenso Kogyo Co., Ltd., trade name: RC-100) was dispersed in the prepared aqueous solution as an oxide support to obtain a suspension. The obtained suspension was dried overnight at 120°C until all water was removed, and then calcined in a calcination furnace in an air atmosphere at 550°C for 4 hours. In a similar process, a mixed aqueous solution was prepared by dissolving 0.6 g of anhydrous sodium nitrate (Kishida Chemical Co., Ltd., product name: special grade sodium nitrate (reagent)) and 6.1 g of calcium nitrate tetrahydrate (Kishida Chemical Co., Ltd., product name: special grade calcium nitrate (tetrahydrate) (reagent)) in 200 mL of ion-exchanged water. 8 g of nickel-supported oxide was then dispersed in the prepared mixed aqueous solution to obtain a suspension. The resulting suspension was dried overnight at 120°C until all water was removed, and then calcined at 600°C for 4 hours. The resulting powder served as the absorption conversion catalyst.

[0052] (Production of hydrocarbon compounds) 150 mg of the obtained absorption catalyst was evaluated using a BELCAT II manufactured by MicrotrackBell. The test conditions were set so that the catalyst layer was heated to 450°C and the total flow rate was 50 mL / min. Prior to performance evaluation, the catalyst was reduced at 450°C with a gas containing 100% H2 gas for 1 hour. In the performance evaluation, the following series of automatically controlled operations was defined as one cycle, and this operation was repeated 73 times. One cycle consisted of four steps: 10% CO2 by volume and 5% O2 by volume gas for 5 minutes, He gas for 5 minutes, H2 gas for 10 minutes, and He gas for 5 minutes. He gas was used as the balance gas unless otherwise noted. The outlet gas concentration was quantified using a MicrotrackBell BELMAS. The results are shown in Table 1.

[0053] In Tables 1 and 2, 1cy indicates the amount of methane produced in the first cycle, and AVE(69-73cy) indicates the arithmetic mean value of the amount of methane produced in the 69th to 73rd cycles. The relative performance value is the value obtained by dividing the arithmetic mean value of the amount of methane produced in the 69th to 73rd cycles by the amount of methane produced in the first cycle. The relative performance value is an index of the durability of the catalyst. In Tables 1 and 2, the column for catalyst composition indicates the metal elements and oxides contained in the absorption conversion catalyst, and the wt% (mass%) is a value calculated based on the charge values ​​shown in the preparation of the absorption conversion catalyst described above. The values ​​in the columns X1 and X2 are values ​​obtained by analyzing the absorption conversion catalyst using the quantitative analysis described above, where X1 indicates the amount of calcium element supported in the absorption conversion catalyst (mmol / g), and X2 indicates the amount of element A supported in the absorption conversion catalyst (mmol / g).

[0054] <Examples 2 to 7> An absorption conversion catalyst was prepared in the same manner as in Example 1, except that the concentration of the mixed aqueous solution of anhydrous sodium nitrate and calcium nitrate tetrahydrate was changed to obtain the catalyst composition shown in Table 1. Furthermore, hydrocarbon compounds were produced using the obtained absorption conversion catalyst. The results are shown in Table 1.

[0055] <Examples 8 to 10> An absorption conversion catalyst was prepared in the same manner as in Example 1, except that anhydrous lithium nitrate (manufactured by Mitsuwa Chemical, trade name: lithium nitrate), anhydrous potassium nitrate (manufactured by Kishida Chemical, trade name: special grade potassium nitrate (reagent)), and magnesium nitrate hexahydrate (manufactured by Kishida Chemical, trade name: special grade magnesium nitrate (hexahydrate) (reagent)) were used instead of anhydrous sodium nitrate, resulting in the catalyst composition shown in Table 2. Furthermore, the obtained absorption conversion catalyst was used to produce hydrocarbon compounds. The results are shown in Table 2.

[0056] <Comparative Examples 1 and 2> An absorption conversion catalyst was prepared in the same manner as in Example 1, except that the concentration of the mixed aqueous solution of anhydrous sodium nitrate and calcium nitrate tetrahydrate was changed to obtain the catalyst composition shown in Table 1. Furthermore, hydrocarbon compounds were produced using the obtained absorption conversion catalyst. The results are shown in Table 1. [Table 1] [Table 2]

[0057] FIG. 1 is a graph in which the vertical axis represents the relative performance values ​​of Examples 1 to 7 and Comparative Examples 1 and 2, and the horizontal axis represents the molar ratio. In FIG. 1, the target relative performance value is preferably 0.4 or higher, more preferably 0.5 or higher, even more preferably 0.6 or higher, particularly preferably 0.8 or higher, particularly preferably 1.1 or higher, and most preferably 1.15 or higher. The numerical ranges of the above formulas (1-1) to (1-6) were set in accordance with the above target relative performance values. In FIG. 1, the relative performance values ​​of Examples 1 to 7 are higher than those of Comparative Examples 1 and 2, compared with the relative performance values ​​of 0.30 and 0.33 obtained in Comparative Examples 1 and 2, demonstrating the effect of mixing Na and Ca and satisfying the above formula (1-1). Additionally, in the cases of Examples 2 and 3, which satisfy formula (1-5), the absorption conversion catalyst exhibits a particularly significant effect, with a relative performance value of 1.1 or higher.

[0058] FIG. 2 is a graph in which the vertical axis represents the amount of methane produced per cy (mmol-CH4 / g-cat) for Examples 1 to 7 and Comparative Examples 1 and 2, and the horizontal axis represents the number of cycles (times) of the repeated performance tests.

[0059] Examples of the inventions that have been understood from the above disclosure are as follows. [1] A carrier; nickel element supported on the support; Calcium element supported on the carrier; and one or more elements A selected from the group consisting of alkali metals and alkaline earth metals excluding calcium, supported on the support, An absorption conversion catalyst in which, when the amount of the calcium element supported in the absorption conversion catalyst is X1 (mmol / g) and the amount of the element A supported in the absorption conversion catalyst is X2 (mmol / g), X1 and X2 satisfy the following formula (1-1): 0.02≦X1 / (X1+X2)≦0.95 (1-1) [2] The absorption conversion catalyst according to [1], wherein the element A is one or more elements selected from the group consisting of lithium, sodium, potassium, and magnesium. [3] The absorption conversion catalyst according to [2], wherein the element A is one or more elements selected from the group consisting of sodium and potassium. [4] The absorption conversion catalyst according to any one of [1] to [3], wherein the X1 and X2 satisfy the following formula (1-5): 0.65≦X1 / (X1+X2)≦0.86 (1-5) [5] The absorption conversion catalyst according to any one of [1] to [4], wherein the support is an oxide support. [6] The absorption conversion catalyst according to [5], wherein the support is one or more supports selected from the group consisting of zirconia supports, alumina supports, and silica supports. [7] (a) a step of preparing an absorption conversion catalyst according to any one of [1] to [6]; (b) contacting the absorption conversion catalyst with a gas containing carbon dioxide to cause the absorption conversion catalyst to occlude carbon dioxide; (c) contacting the carbon dioxide-occluded absorption conversion catalyst with a reducing gas to obtain a hydrocarbon compound; A method for producing a hydrocarbon compound, comprising: [8] The method for producing a hydrocarbon compound according to [7], wherein the carbon dioxide-containing gas contains oxygen.

Claims

1. A carrier; nickel element supported on the support; Calcium element supported on the carrier; and one or more elements A selected from the group consisting of alkali metals and alkaline earth metals excluding calcium, supported on the support, When the amount of the calcium element supported in the absorption conversion catalyst is X1 (mmol / g) and the amount of the element A supported in the absorption conversion catalyst is X2 (mmol / g), X1 and X2 satisfy the following formula (1-1): 0.02≦X1 / (X1+X2)≦0.95 (1-1)

2. 2. The absorption conversion catalyst according to claim 1, wherein the element A is one or more elements selected from the group consisting of lithium, sodium, potassium, and magnesium.

3. 3. The absorption conversion catalyst according to claim 2, wherein the element A is one or more elements selected from the group consisting of sodium and potassium.

4. The absorption conversion catalyst according to any one of claims 1 to 3, wherein X1 and X2 satisfy the following formula (1-5): 0.65≦X1 / (X1+X2)≦0.86 (1-5)

5. The absorption conversion catalyst according to any one of claims 1 to 3, wherein the support is an oxide support.

6. 6. The absorption conversion catalyst according to claim 5, wherein the support is one or more supports selected from the group consisting of zirconia supports, alumina supports, and silica supports.

7. (a) preparing an absorption conversion catalyst according to any one of claims 1 to 3; (b) contacting the absorption conversion catalyst with a gas containing carbon dioxide to allow the absorption conversion catalyst to occlude carbon dioxide; (c) contacting the absorption conversion catalyst having carbon dioxide occluded therein with a reducing gas to obtain a hydrocarbon compound; A method for producing a hydrocarbon compound, comprising:

8. The method for producing a hydrocarbon compound according to claim 7 , wherein the carbon dioxide-containing gas contains oxygen.

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