Carbon dioxide reduction catalyst device, carbon dioxide reduction method, and method for producing catalyst

Abstract

The problem to be solved by the present invention is to provide a carbon dioxide reduction catalyst device capable of preferably generating hydrocarbons having 8-16 carbon atoms by means of a hydrogenation reaction of carbon dioxide. In order to solve the above-mentioned problem, the present invention provides a carbon dioxide reduction catalyst device which reduces carbon dioxide and generates hydrocarbons by hydrogenating carbon dioxide, and which comprises: a first catalyst that contains Fe and at least one of Ga and Zr as a catalyst metal; and a second catalyst comprising Fe and Co as catalyst metals, the second catalyst is disposed on the downstream side of the first catalyst.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide reduction catalyst device, a carbon dioxide reduction method, and a method for manufacturing a catalyst. Background Art

[0002] Efforts have been continuously made to mitigate climate change or reduce its impact. To achieve this goal, automotive exhaust emission regulations are being further promoted. In particular, it is necessary to reduce the carbon dioxide emissions contained in the exhaust gas of internal combustion engines.

[0003] In recent years, a technology for hydrogenating carbon dioxide to produce fuel has been known. For example, as a catalyst for synthesizing methanol from a mixed gas of carbon dioxide and hydrogen, a catalyst composed of Cu, Zn, and alumina has been proposed (see Patent Document 1).

[0004] As the fuel obtained by hydrogenating carbon dioxide, it is necessary to be able to produce hydrocarbons having 5 or more carbon atoms, which can be used as liquid fuels. As such a technology, the following method has been proposed: in the Fischer-Tropsch (FT) synthesis reaction, potassium is used as a promoter for the Fe catalyst, whereby a highly branched product having 5 or more carbon atoms is prepared (see Patent Document 2).

[0005] [Prior Art Documents]

[0006] (Patent Documents)

[0007] Patent Document 1: Japanese Patent Publication No. 45-16682

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2005-537340 Summary of the Invention

[0009] [Problems to be Solved by the Invention]

[0010] However, in the effort to reduce carbon dioxide emissions, technologies related to aviation fuels made from biomass-derived raw materials or waste, i.e., Sustainable Aviation Fuel (SAF), have attracted attention. It is preferable to be able to directly produce SAF from carbon dioxide using technologies related to the hydrogenation reaction of carbon dioxide. However, the hydrocarbons generated using the technology disclosed in Patent Document 2 have the following problem: the production rate of hydrocarbons having 8 to 16 carbon atoms, which are the main components of SAF, is low.

[0011] The present invention has been made in view of the above problems, and an object thereof is to provide a carbon dioxide reduction catalyst device that can preferably produce hydrocarbons having 8 to 16 carbon atoms by the hydrogenation reaction of carbon dioxide.

[0012] [Technical means for solving the problem]

[0013] (1) The present invention relates to a carbon dioxide reduction catalyst device that causes a hydrogenation reaction of carbon dioxide to reduce carbon dioxide and produce hydrocarbons. The carbon dioxide reduction catalyst device has: a first catalyst including at least any one of Fe and Ga or Zr as a catalyst metal; and a second catalyst including Fe and Co as catalyst metals; and the second catalyst is disposed on the downstream side of the first catalyst.

[0014] (2) The carbon dioxide reduction catalyst device according to (1), wherein at least any one of the first catalyst and the second catalyst further includes Na as a catalyst metal.

[0015] (3) The carbon dioxide reduction catalyst device according to (2), wherein at least any one of the first catalyst and the second catalyst includes 0.5 to 1.5% by mass of Na in the catalyst metal.

[0016] (4) The carbon dioxide reduction catalyst device according to any one of (1) to (3), wherein the second catalyst includes 10 to 40% by mass of Co in the catalyst metal.

[0017] (5) The carbon dioxide reduction catalyst device according to any one of (1) to (4), wherein a dehydration section is provided between the first catalyst and the second catalyst.

[0018] (6) The carbon dioxide reduction catalyst device according to any one of (1) to (5), wherein the first catalyst contains at least any one of an Fe-Ga composite oxide containing Fe and Ga and an Fe-Zr composite oxide containing Fe and Zr.

[0019] (7) Further, the present invention relates to a carbon dioxide reduction method using the carbon dioxide reduction catalyst device according to any one of (1) to (6), and the catalyst temperature T2 of the second catalyst is lower than the catalyst temperature T1 of the first catalyst.

[0020] (8) The carbon dioxide reduction method according to (7), wherein the catalyst temperature T2 is in the range of 260°C to 340°C.

[0021] (9) Further, the present invention relates to a method for manufacturing a catalyst, which is the method for manufacturing the aforementioned first catalyst described in (1), and has a coprecipitation step of extracting a precipitate from an aqueous solution by coprecipitation, where the aqueous solution is prepared by dissolving at least any one of the aforementioned nitrate of Fe, the aforementioned nitrate of Ga, and the aforementioned nitrate of Zr in a specific amount of distilled water.

[0022] (10) According to the method for manufacturing a catalyst described in (9), after the aforementioned coprecipitation step, there is an impregnation step of dropping an aqueous solution containing Na onto the aforementioned precipitate, drying for a specific time, and sintering the obtained powder at a specific temperature.

[0023] (11) According to the method for manufacturing a catalyst described in (9) or (10), in the aforementioned coprecipitation step, an aqueous urea solution is dropped into the aqueous solution, whereby a precipitation solution is obtained, and the aqueous solution is prepared by dissolving at least any one of the aforementioned nitrate of Fe, the aforementioned nitrate of Ga, and the aforementioned nitrate of Zr in a specific amount of distilled water.

[0024] (Effects of the Invention)

[0025] According to the present invention, a carbon dioxide reduction catalyst device can be provided, which can preferably generate hydrocarbons having 8 to 16 carbon atoms by the hydrogenation reaction of carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a diagram showing the configuration of the carbon dioxide reduction catalyst device of the first embodiment (Example 1).

[0027] Figure 2A It is a diagram showing the configuration of the carbon dioxide reduction catalyst device of the second embodiment (Example 2).

[0028] Figure 2B It is a diagram showing the configuration of the carbon dioxide reduction catalyst device of the comparative example.

[0029] Figure 2C It is a diagram showing the configuration of the carbon dioxide reduction catalyst device of the comparative example.

[0030] Figure 3 It is a chart comparing the C 8 -C 16 yields of the carbon dioxide reduction catalyst devices of the examples and the comparative examples.

[0031] Figure 4A It is a chart showing the relationship between the carbon number and the selectivity of the carbon dioxide reduction catalyst device of Comparative Example 1.

[0032] Figure 4BIt is a graph showing the relationship between the carbon number and the selectivity of the carbon dioxide reduction catalyst device of Comparative Example 2.

[0033] Figure 4C It is a graph showing the relationship between the carbon number and the selectivity of the carbon dioxide reduction catalyst device of Example 1.

[0034] Figure 5 It shows the C of Examples and Comparative Examples 8 -C 16 selectivity and CO 2 conversion rate and C 8 -C 16 table of the relationship with the yield.

[0035] Figure 6A It is a graph showing the relationship between the Na addition amount of Examples and Comparative Examples and CO 2 conversion rate.

[0036] Figure 6B It is a graph showing the relationship between the Na addition amount of Examples and Comparative Examples and C 8 -C 16 selectivity.

[0037] Figure 6C It is a graph showing the relationship between the Na addition amount of Examples and Comparative Examples and C 8 -C 16 generation rate.

[0038] Figure 7A It is a graph showing the relationship between the Co addition amount of Examples and Comparative Examples and CO 2 conversion rate.

[0039] Figure 7B It is a graph showing the relationship between the Co addition amount of Examples and Comparative Examples and C 8 -C 16 selectivity.

[0040] Figure 7C It is a graph showing the relationship between the Co addition amount of Examples and Comparative Examples and C 8 -C 16 generation rate. Detailed implementation mode

[0041] <Carbon dioxide reduction catalyst device>

[0042] 《First Embodiment》

[0043] As Figure 1As shown, the carbon dioxide reduction catalyst device 1 of the present embodiment has: a catalyst reactor 20 having a first catalyst C1; and a catalyst reactor 30 having a second catalyst C2. The catalyst reactor 20 and the catalyst reactor 30 are connected by a flow path L, with the catalyst reactor 20 provided on the upstream side and the catalyst reactor 30 provided on the downstream side respectively.

[0044] (First Catalyst)

[0045] The first catalyst C1 of the carbon dioxide reduction catalyst of the present embodiment must include Fe (iron) as a catalyst metal and at least one of Ga (gallium) or Zr (zirconium). In addition, it is preferably further included Na (sodium). The carbon dioxide reduction reaction using the first catalyst C1 of the present embodiment is the following reaction: using a mixed gas of H 2 (hydrogen) and CO 2 (carbon dioxide) as a raw material, the reverse water gas shift reaction of reducing CO 2 to CO (carbon monoxide) and the FT synthesis reaction of converting CO into hydrocarbons are carried out in one step, thereby generating hydrocarbons. The catalyst of the present embodiment contributes to both the above-mentioned reverse water gas shift reaction and FT synthesis reaction. Compared with the conventional FT synthesis reaction, the carbon dioxide reduction reaction using the catalyst of the present embodiment can efficiently generate hydrocarbons with 8 to 16 carbon atoms, for example, at a high flow rate of about Space Velocity (SV) = 5,000 h -1 .

[0046] The Fe contained in the catalyst metal of the first catalyst C1 can be a compound such as an oxide, carbonate, nitrate, sulfate, etc., and is preferably an oxide. These compounds can contain two or more. In addition, Fe is more preferably included in the catalyst metal as at least one of an Fe-Ga composite oxide including Fe and Ga and an Fe-Zr composite oxide including Fe and Zr. By using a catalyst metal containing at least one of an Fe-Ga composite oxide and an Fe-Zr composite oxide, Fe particles can be carbonized in the FT synthesis reaction, thereby promoting the CH 2 growth reaction in the catalyst and thus promoting the growth of the carbon chain.

[0047] The content of Fe in the catalyst metal of the first catalyst C1 is preferably 55 to 90% by mass in terms of metal atoms, and more preferably 60 to 75% by mass.

[0048] Similar to Fe, Ga contained in the catalyst metal of the first catalyst C1 may be a compound such as an oxide, a carbonate compound, a nitrate compound, or a sulfate compound, and is preferably an oxide. These compounds may contain two or more. Ga is more preferably included in the catalyst metal as an Fe-Ga composite oxide including Fe and Ga.

[0049] The content of Ga in the catalyst metal of the first catalyst C1 is preferably 10 to 30% by mass in terms of metal atoms, and more preferably 20 to 30% by mass. When the content of Ga is less than 10% by mass, the atomization of the catalyst metal may sometimes be insufficient. By setting the content of Ga to 30% by mass or less, the adverse effects caused by Ga covering the reaction sites of Fe can be avoided, and thus the decrease in catalyst activity can be prevented.

[0050] Similar to Fe, Zr contained in the catalyst metal of the first catalyst C1 may be a compound such as an oxide, a carbonate compound, a nitrate compound, or a sulfate compound, and is preferably an oxide. These compounds may contain two or more. Zr is more preferably included in the catalyst metal as an Fe-Zr composite oxide including Fe and Zr.

[0051] The content of Zr in the catalyst metal is preferably more than 0% by mass and 15% by mass or less in terms of metal atoms, and more preferably 5 to 10% by mass. By setting the content of Zr to 15% by mass or less, the adverse effects caused by Zr covering the reaction sites of Fe can be avoided, and thus the decrease in catalyst activity can be prevented.

[0052] The catalyst metal of the first catalyst C1 may include any one of Ga and Zr. When the catalyst metal includes any one of Ga and Zr, these catalyst metals are more preferably included in the catalyst metal as an Fe-Ga-Zr composite oxide including Fe, Zr, and Ga. Compared with compounds such as iron oxide, since the Fe-Ga-Zr composite oxide is atomized, the reaction sites of the Fe catalyst are increased, and thus the reaction time of the FT synthesis reaction, that is, the time for the carbon chain of the generated hydrocarbon to grow, can be ensured.

[0053] The first catalyst C1 preferably further includes Na as a catalyst metal. Na functions as a promoter in the catalyst metal, causing CO 2 to become Na 2 CO 3 to capture, and thereby promoting the reverse water-gas shift reaction of generating CO from H 2 and CO 2 so as to be able to increase CO 2Conversion rate. Different from the Fe-Zr composite oxide or the Fe-Ga-Zr composite oxide, Na preferably exists in the form of an oxide or the like on the surface of the Fe-Zr composite oxide or the Fe-Ga-Zr composite oxide. In addition, the catalyst metal may contain an alkali metal such as Li, K, Rb, Cs, etc. instead of Na or together with Na.

[0054] The content of Na in the catalyst metal of the first catalyst C1 is preferably 0.5 to 1.5% by mass, more preferably 1.0% by mass. By setting the content of Na to 0.5% by mass or more, the production efficiency of hydrocarbons having 8 to 16 carbon atoms can be sufficiently improved. In addition, by setting the content of Na to 1.5% by mass or less, the adverse effects caused by Na covering the reaction sites of Fe can be avoided, and thus the decrease in catalyst activity can be prevented.

[0055] (Second catalyst)

[0056] The second catalyst C2 must include Fe (iron) and Co (cobalt) as catalyst metals. In addition, it is preferably further included Na (sodium). The second catalyst C2 is arranged on the downstream side of the first catalyst C1 to increase the carbon number of the hydrocarbons generated by the first catalyst C1, thereby increasing the production rate (yield) of hydrocarbons having 8 to 16 carbon atoms.

[0057] The Fe contained in the catalyst metal of the second catalyst C2 may be a compound such as an oxide, a carbonate compound, a nitrate compound, a sulfate compound, etc., preferably an oxide. These compounds may contain two or more. In addition, Fe is more preferably included in the catalyst metal as an Fe-Co composite oxide including Fe and Co. By using a catalyst metal containing an Fe-Co composite oxide, since Co itself has carbon chain growth reactivity, compared with compounds such as iron oxide, the growth of the carbon chain can be promoted.

[0058] The content of Fe in the catalyst metal of the second catalyst C2 is preferably 60 to 90% by mass, more preferably 70 to 80% by mass in terms of metal atoms.

[0059] Similar to Fe, the Co contained in the catalyst metal of the second catalyst C2 may be a compound such as an oxide, a carbonate compound, a nitrate compound, a sulfate compound, etc., preferably an oxide. These compounds may contain two or more. Co is more preferably included in the catalyst metal as an Fe-Co composite oxide including Fe and Co.

[0060] The content of Co in the catalyst metal of the second catalyst C2 is preferably 10 to 40% by mass, more preferably 20 to 30% by mass, in terms of metal atoms. By setting the content of Co to 10% by mass or more, the carbon growth reactivity of Co itself can be exhibited. By setting the content of Co to 40% by mass or less, the formation of by-product methane can be suppressed. The function of reducing carbon dioxide in the iron catalyst to carbon monoxide (reverse water-gas shift reaction) can also be maintained.

[0061] The second catalyst C2 preferably further includes Na as a catalyst metal. Na functions as a promoter in the catalyst metal. Different from the Fe-Co composite oxide, Na preferably exists on the surface of the Fe-Co composite oxide in the form of an oxide or the like. In addition, the catalyst metal may contain alkali metals such as Li, K, Rb, and Cs instead of Na or together with Na.

[0062] The content of Na in the catalyst metal of the second catalyst C2 is preferably 0.5 to 1.5% by mass, more preferably 1.0% by mass. By setting the content of Na to 0.5% by mass or more, the alkalinity of the iron catalyst can be increased, and the production efficiency of hydrocarbons having 8 to 16 carbon atoms can be sufficiently increased. In addition, by setting the content of Na to 1.5% by mass or less, the adverse effects caused by Na covering the reaction sites of Fe can be avoided, the formation of by-product carbon monoxide can be suppressed, and thus the decrease in catalyst activity can be prevented.

[0063] (Catalyst reactor)

[0064] The configuration of the catalyst reactor 20 and the catalyst reactor 30 is not particularly limited, and a known configuration can be applied. For example, a fixed-bed flow-through reaction device can be cited, in which a powdery, granular or pelletized catalyst or a carrier supporting a catalyst is filled in a flow path having a specific shape. The catalyst reactor 20 and the catalyst reactor 30 are independent of each other, and the catalyst temperature can be set to different temperatures using a heating device (not shown).

[0065] 《Second Embodiment》

[0066] Next, use Figure 2A The configuration of the carbon dioxide reduction catalyst device 1a according to the second embodiment of the present invention will be described. The configuration of the carbon dioxide reduction catalyst device 1a is the same as that of the first embodiment except that a dehydration unit 40 is provided in the middle of the flow path L.

[0067] (Dehydration unit)

[0068] The dehydration unit 40 removes water from the fluid supplied to the second catalyst C2. Thereby, in the catalytic reaction using the second catalyst C2, the chemical equilibrium can be shifted in the direction of increasing the carbon number of hydrocarbons. Therefore, the yield of hydrocarbons having 8 to 16 carbon atoms can be increased.

[0069] As the dehydration unit 40, a conventionally well-known dehydration unit can be used. For example, the following configurations can be cited: It is composed of a bent pipe, condensate water is stored in the bent portion, and condensate water exceeding a certain amount is discharged to the outside of the system. In addition to the above, the dehydration unit 40 can also have the following configuration: The pipe itself is cooled by water cooling or the like to remove condensate water. They can be used alone or in combination of multiple.

[0070] <Carbon dioxide reduction method>

[0071] The carbon dioxide reduction method of the present embodiment is carried out using the above-described carbon dioxide reduction catalyst device 1 or 1a. The carbon dioxide reduction method includes: a first catalytic reaction step of bringing a gas containing carbon dioxide into contact with a first catalyst C1 disposed on the upstream side; and a second catalytic reaction step of bringing a gas containing the hydrocarbon generated by the above-described first catalytic reaction step into contact with a second catalyst C2 disposed on the downstream side to increase the carbon number. Between the first catalytic reaction step and the second catalytic reaction step, the following step can also be included: Using the dehydration unit 40, water is removed from the gas containing the hydrocarbon generated by the above-described first catalytic reaction step.

[0072] The catalyst temperature T2 of the second catalyst C2 in the second catalytic reaction step is preferably lower than the catalyst temperature T1 of the first catalyst C1 in the first catalytic reaction step. Thereby, the activity of Co included in the second catalyst can be controlled, and thus the yield of hydrocarbons having 8 to 16 carbon atoms can be further increased.

[0073] The catalyst temperature T1 is, for example, preferably 340 to 400 °C, and the catalyst temperature T2 is, for example, preferably 260 to 340 °C.

[0074] <Manufacturing method of the first catalyst>

[0075] The manufacturing method of the first catalyst of the present embodiment preferably has a coprecipitation step and an impregnation step.

[0076] (Coprecipitation step)

[0077] The coprecipitation process is as follows: a precipitate as a catalyst precursor is extracted from an aqueous solution by coprecipitation. The aqueous solution is prepared by dissolving at least one of iron nitrate, gallium nitrate, and zirconium nitrate in a specific amount of distilled water. By the coprecipitation process, at least one of an Fe-Ga composite oxide, an Fe-Zr composite oxide, and an Fe-Ga-Zr composite oxide is formed. In the coprecipitation process, it is preferable to drop a urea aqueous solution into the above aqueous solution containing at least one of Fe and Ga and Zr to obtain a precipitation solution. Thereafter, the precipitate is separated from the precipitation solution by filtration, washing, etc., and dried to obtain a precipitate (Fe-Ga composite oxide, Fe-Zr composite oxide, Fe-Ga-Zr composite oxide) as a catalyst precursor.

[0078] (Impregnation process)

[0079] The impregnation process is as follows: an aqueous solution containing Na is dropped into the precipitate obtained by the coprecipitation process, dried for a specific time, and the resulting powder is sintered at a specific temperature. By the impregnation process, the Na compound can be concentrated near the surface of the above composite oxide. As the aqueous solution containing Na, for example, NaNO 3 aqueous solution. NaNO 3 The aqueous solution can be dropped under ultrasonic vibration. Thereby, the Na compound can be uniformly concentrated near the surface of the above composite oxide. The sintering temperature can be, for example, 550 °C, and the sintering time can be 4 hours.

[0080] <Manufacturing method of the second catalyst>

[0081] The manufacturing method of the second catalyst of the present embodiment preferably has a hydrothermal synthesis process and an impregnation process.

[0082] (Hydrothermal synthesis process)

[0083] The hydrothermal synthesis process is as follows: a precipitate as a catalyst precursor is extracted from an aqueous solution by hydrothermal synthesis. The aqueous solution is prepared by dissolving iron nitrate and cobalt nitrate in a specific amount of urea aqueous solution. By the hydrothermal synthesis process, an Fe-Co composite oxide is formed. In the hydrothermal synthesis process, it is preferable to perform a hydrothermal synthesis process on the above aqueous solution containing Fe and Co using an autoclave. Thereby, a precipitation solution is obtained. Thereafter, the precipitate is separated from the precipitation solution by filtration, washing, etc., and dried to obtain a precipitate (Fe-Co composite oxide) as a catalyst precursor.

[0084] (Impregnation process)

[0085] The impregnation process can be the same process as the impregnation process in the manufacturing method of the above first catalyst.

[0086] The present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0087] Example

[0088] Next, examples of the present invention will be described, but the present invention is not limited to these examples.

[0089] <Example 1>

[0090] [Preparation of the first catalyst]

[0091] Weigh the nitrate of Fe (Fe(NO 3 )) 3 ·9H 2 O), the nitrate of Zr (ZrO(NO 3 )) 2 ·2H 2 O), and the nitrate of Ga (Ga(NO 3 )) 3 ·6H 2 O), which are the catalyst metals of the first catalyst, in a mass ratio of Fe:Zr:Ga of 6:1:3 in terms of metal atoms, and dissolve them in distilled water. Next, while stirring the above aqueous solution, dropwise add an aqueous solution of CH 4 N 2 O at a rate of 2 ml / min to fix the pH at 8.5, thereby obtaining a precipitation solution containing Fe, Zr, and Ga as precipitates. Next, after aging the precipitation solution at room temperature for 24 hours, filter and wash repeatedly to separate the precipitate. Dry the separated precipitate at 60 °C for 12 hours to obtain a Fe-Ga-Zr catalyst precursor.

[0092] Under ultrasonic vibration at 92 kHz, dropwise add an aqueous solution of NaNO 3 to the above Fe-Ga-Zr catalyst precursor so that the Na content is 1.0% by mass. Next, dry it under a vacuum of 5000 Pa for 1 hour, and further dry it at 60 °C for 12 hours at normal pressure to obtain a powder. Sinter the obtained powder at 550 °C for 4 hours to obtain the first catalyst of Example 1.

[0093] [Preparation of the second catalyst]

[0094] Weigh the nitrate of Fe (Fe(NO 3 )) 3 ·9H 2O), nitrate of Co which is also a catalyst metal (Co(NO 3 ) 2 ·6H 2 O), is dissolved in urea water. Then, after stirring the above aqueous solution for 1 hour, it is transferred to an autoclave container and hydrothermally synthesized at 120 °C for 12 hours to obtain a precipitation solution including Fe and Co as precipitates. Then, after aging the precipitation solution at room temperature for 24 hours, it is repeatedly filtered and washed, thereby separating the precipitate. The separated precipitate is dried at 60 °C for 12 hours, thereby obtaining an Fe-Co catalyst precursor.

[0095] Under ultrasonic vibration at 92 kHz, an aqueous solution of NaNO 3 with a Na content of 1.0 mass% is dropped into the above Fe-Co catalyst precursor. Then, it is dried under a vacuum of 5000 Pa for 1 hour, and further dried at 60 °C for 12 hours under normal pressure to obtain a powder. The obtained powder is sintered at 550 °C for 4 hours, thereby obtaining the second catalyst of Example 1.

[0096] [Fabrication of Carbon Dioxide Reduction Catalyst Device]

[0097] Using the first catalyst and the second catalyst obtained above, the Figure 1 shown carbon dioxide reduction catalyst device 1 is fabricated. A fixed-bed flow-through reaction device is used for the catalyst reactor, and the first catalyst is 0.25 g of pellet-shaped catalyst formed into a square with a side length of 0.4 - 0.8 mm. The above pellets are filled in a reaction tube (inner diameter 6 mm) with a length of 5 cm for use. The second catalyst also has the same shape, weight, and filling amount as the first catalyst. For the reaction temperature, the catalyst temperature T1 of the first catalyst is set to 380 °C, and the catalyst temperature T2 of the second catalyst is set to 300 °C.

[0098] [Example 2]

[0099] Fabricate the Figure 2A shown carbon dioxide reduction catalyst device 1a, which is the same as Example 1 except for this.

[0100] [Example 3]

[0101] Set the catalyst temperature T2 of the second catalyst to 220 °C, which is the same as Example 2 except for this.

[0102] [Example 4]

[0103] Set the catalyst temperature T2 of the second catalyst to 260 °C, which is the same as Example 2 except for this.

[0104] [Example 5]

[0105] The catalyst temperature T2 of the second catalyst was set at 340 °C, and otherwise it was the same as in Example 2.

[0106] <Example 6>

[0107] The second catalyst was prepared such that the Na content (addition amount) of the second catalyst was 0.5% by mass, and otherwise it was the same as in Example 2.

[0108] <Example 7>

[0109] The second catalyst was prepared such that the Na content (addition amount) of the second catalyst was 1.5% by mass, and otherwise it was the same as in Example 2.

[0110] <Example 8>

[0111] The second catalyst was prepared such that the Co content (addition amount) of the second catalyst was 10% by mass, and otherwise it was the same as in Example 2 (the second catalyst was prepared such that the Fe content was 89% by mass and the Na content was 1.0% by mass).

[0112] <Example 9>

[0113] The second catalyst was prepared such that the Co content (addition amount) of the second catalyst was 25% by mass, and otherwise it was the same as in Example 2 (the second catalyst was prepared such that the Fe content was 74% by mass and the Na content was 1.0% by mass).

[0114] <Example 10>

[0115] The second catalyst was prepared such that the Co content (addition amount) of the second catalyst was 40% by mass, and otherwise it was the same as in Example 2 (the second catalyst was prepared such that the Fe content was 59% by mass and the Na content was 1.0% by mass).

[0116] <Comparative Example 1>

[0117] Only the first catalyst obtained above was used to fabricate Figure 2B the carbon dioxide reduction catalyst device 1b shown, and otherwise it was the same as in Example 1. Additionally, as Figure 2B shown, the carbon dioxide reduction catalyst device 1b only had a catalyst reactor 20 as the catalyst reactor, and the catalyst reactor 20 had the first catalyst C1. The catalyst temperature T1 of the first catalyst was 380 °C.

[0118] <Comparative Example 2>

[0119] The first catalyst and the second catalyst obtained above were used to fabricate Figure 2CThe carbon dioxide reduction catalyst device 1c shown is the same as that in Example 1 except for the following. In addition, in the carbon dioxide reduction catalyst device 1c, as Figure 2C shown, the first catalyst C1 and the second catalyst C2 are filled into the same catalyst reactor 21, and adjusted to the same catalyst temperature. The catalyst temperature T1 of the first catalyst and the catalyst temperature T2 of the second catalyst are set to 380 °C.

[0120] <Comparative Example 3>

[0121] The second catalyst is produced without adding Na thereto, and is the same as Example 2 except for the following.

[0122] <Comparative Example 4>

[0123] The second catalyst is produced without adding Co thereto, and is the same as Example 2 except for the following.

[0124] [Evaluation]

[0125] Using the carbon dioxide reduction catalyst devices of the above respective Examples and Comparative Examples, the carbon dioxide reduction reaction is carried out by the following method. The reaction gas is 0.28 NL / h of CO 2 , 0.84 NL / h of H 2 (CO 2 / H 2 = 1 / 3). W / F (catalyst weight / gas flow rate) is 5.0 g·h / mol, and the space velocity (SV) = 5,000 h -1 . The pressure is 3 MPa, and the reaction time is 4 hours. An online gas chromatograph (Shimadzu, GC-2014AT, detector: Thermal Conductivity Detector (TCD)) and a flame ionization detector (FID) (Shimadzu, GC-2014AF) are used to qualitatively and quantitatively analyze the gas components after the catalytic reaction. In addition, an offline gas chromatograph (Shimadzu, GC-2014AF, detector: flame ionization detector (FID)) is used to qualitatively and quantitatively analyze the liquid components after the catalytic reaction.

[0126] (CO 2 conversion rate)

[0127] The CO 2 conversion rate of the above carbon dioxide reduction reaction is obtained according to the following formula (1). The results are shown in Figure 5 , Figure 6A and Figure 7A .

[0128] CO 2 Conversion rate (%) = ((CO concentration before reaction) - (CO concentration after reaction)) / (CO concentration before reaction) × 100…(1) 2 concentration) - (CO concentration after reaction 2 concentration)) / (CO concentration before reaction 2 concentration) × 100…(1)

[0129] (C 8-16 selectivity)

[0130] The selectivity of hydrocarbons (C) with 8 to 16 carbon atoms produced by the above carbon dioxide reduction reaction is calculated according to the following formula (2). The results are shown in 8-16 ), Figure 5 , Figure 6B and Figure 7B . In addition, the selectivity of hydrocarbons with each carbon number and structure is calculated by the same method as formula (2), and the results are shown in Figures 4A to 4C .

[0131] C 8-16 Selectivity (%) = (concentration of component containing C 8-16 component) / ((CO concentration before reaction) - (CO concentration after reaction)) × 100…(2) 2 concentration) - (CO concentration after reaction 2 concentration)) × 100…(2)

[0132] (C 8-16 production rate (yield))

[0133] The production rate of hydrocarbons (C) with 8 to 16 carbon atoms produced by the above carbon dioxide reduction reaction is calculated according to the following formula (3). The results are shown in 8-16 ), Figure 3 , Figure 5 , Figure 6C and Figure 7C .

[0134] C 8-16 Production rate (%) = CO 2 conversion rate × C 8-16 selectivity / 100…(3)

[0135] As Figure 3 shown, the following results can be seen: The C 8-16 production rate (yield) of the carbon dioxide reduction catalyst device in each example is higher than that of the carbon dioxide reduction catalyst device in each comparative example.

[0136] Figure 4A is a graph showing the carbon number of hydrocarbons produced by the carbon dioxide reduction catalyst device of Comparative Example 1 and the selectivity of hydrocarbons with each carbon number. Similarly, Figure 4B is a graph corresponding to Comparative Example 2,Figure 4C It is a diagram corresponding to Example 1. Figures 4A to 4C In " Figures 4A to 4C ", "Paraffins" refers to saturated chain hydrocarbons with a straight-chain structure. "Iso-paraffins" refers to saturated chain hydrocarbons with a branched-chain structure. "Olefins" refers to chain hydrocarbons with a double bond.

[0137] As Figure 4A shown, the C 8-16 generation rate of the carbon dioxide reduction catalyst device of Comparative Example 1 using only the first catalyst is 15% or less. In addition, as Figure 4B shown, for the carbon dioxide reduction catalyst device of Comparative Example 2 using the first catalyst and the second catalyst at the same catalyst temperature, the result is that the C 8-16 generation rate is slightly higher than that of Comparative Example 1, but the generation rate of hydrocarbons with fewer carbon atoms such as methane is high. As Figure 4C shown, for the carbon dioxide reduction catalyst device of Example 1 where the catalyst temperature of the first catalyst is set higher than that of the second catalyst, the result is that compared with Comparative Example 2, the C 8-16 generation rate is further increased, and the generation rate of hydrocarbons with fewer carbon atoms such as methane is decreased.

[0138] Figure 5 It is a table showing the C 8-16 selectivity, CO 2 conversion rate, and the relationship between these results and the C 8-16 generation rate (yield). As Figure 5 shown, by setting the catalyst temperature of the first catalyst to 380 °C and the catalyst temperature of the second catalyst to 260 °C to 340 °C, the C 8-16 generation rate (yield) can be made 20% or more.

[0139] Figure 6A , Figure 6B , Figure 6C are charts for comparing the CO 2 conversion rate, C 8-16 selectivity, and C 8-16 generation rate (yield) respectively when only the Na addition amount of the second catalyst is changed under the same conditions. From the results of Figure 6A , Figure 6B and Figure 6C , it is speculated that the higher the Na addition amount, the higher the C 8-16 generation activity. However, if it exceeds 1.0 mass%, Na will cover the reaction sites of the Fe catalyst, resulting in a monotonous decrease in activity. Therefore, it can be seen that the Na addition amount is preferably in the range of 0.5 to 1.5 mass%. In particular, it can be seen that all the results of Example 2 with a Na addition amount of 1.0 mass% are excellent and most preferred.

[0140] Figure 7A 、 Figure 7B 、 Figure 7C are charts for comparing the CO 2 conversion rate, C 8-16 selectivity, and C 8-16 formation rate (yield) when only the Co addition amount of the second catalyst is changed under the same conditions. The higher the Co addition amount, the higher the C 8-16 formation activity. However, if it exceeds 25% by mass, Co will cover the reaction sites of the Fe catalyst, resulting in a monotonous decrease in activity and the by-production of methane. Therefore, it can be seen that the Co addition amount is preferably in the range of 10 to 40% by mass. In particular, it can be seen that all the results of Example 9 with a Co addition amount of 25% by mass are excellent and most preferred.

[0141] Reference numeral

[0142] 1, 1a Carbon dioxide reduction catalyst device

[0143] C1 First catalyst

[0144] C2 Second catalyst

[0145] 40 Dehydration section

Claims

1. A carbon dioxide reduction catalyst device that causes a hydrogenation reaction of carbon dioxide to reduce carbon dioxide and produce hydrocarbons, the carbon dioxide reduction catalyst device having: A first catalyst including at least any one of Fe and Ga or Zr as a catalyst metal; and, A second catalyst including Fe and Co as catalyst metals; and, The second catalyst is disposed on the downstream side of the first catalyst.

2. The carbon dioxide reduction catalyst device according to claim 1, wherein, At least any one of the first catalyst and the second catalyst further includes Na as a catalyst metal.

3. The carbon dioxide reduction catalyst device according to claim 2, wherein, At least any one of the first catalyst and the second catalyst includes 0.5 to 1.5% by mass of Na in the catalyst metal.

4. The carbon dioxide reduction catalyst device according to claim 1 or 2, wherein, The second catalyst includes 10 to 40% by mass of Co in the catalyst metal.

5. The carbon dioxide reduction catalyst device according to claim 1 or 2, wherein, A dehydration section is provided between the first catalyst and the second catalyst.

6. The carbon dioxide reduction catalyst device according to claim 1 or 2, wherein, The first catalyst contains at least any one of an Fe-Ga composite oxide containing Fe and Ga and an Fe-Zr composite oxide containing Fe and Zr.

7. A carbon dioxide reduction method using the carbon dioxide reduction catalyst device according to claim 1, The catalyst temperature T2 of the second catalyst is lower than the catalyst temperature T1 of the first catalyst.

8. The carbon dioxide reduction method according to claim 7, wherein, The catalyst temperature T2 is 260 to 340 °C.

9. A method for manufacturing a catalyst, which is a method for manufacturing the first catalyst according to claim 1, and, Has a coprecipitation step, the coprecipitation step extracts a precipitate from an aqueous solution by coprecipitation, and the aqueous solution is obtained by dissolving at least any one of the nitrate of the aforementioned Fe, the nitrate of the aforementioned Ga, and the nitrate of the aforementioned Zr in a specific amount of distilled water.

10. The method for manufacturing a catalyst according to claim 9, wherein, After the coprecipitation step, there is an impregnation step, the impregnation step drops an aqueous solution containing Na onto the precipitate, dries for a specific time, and sinters the obtained powder at a specific temperature.

11. The method for manufacturing a catalyst according to claim 9 or 10, wherein, In the coprecipitation step, an aqueous urea solution is dropped into the aqueous solution, whereby a precipitation solution is obtained, and the aqueous solution is obtained by dissolving at least any one of the nitrate of the aforementioned Fe, the nitrate of the aforementioned Ga, and the nitrate of the aforementioned Zr in a specific amount of distilled water.

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