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

Abstract

The problem to be solved by the present invention is to provide a carbon dioxide reduction catalyst which can preferably produce hydrocarbons having 8-16 carbon atoms by means of a hydrogenation reaction of carbon dioxide. [Solution] An aspect of the present invention is a carbon dioxide reduction catalyst in which carbon dioxide is subjected to a hydrogenation reaction to reduce carbon dioxide and produce hydrocarbons, the carbon dioxide reduction catalyst containing Fe, Co and Zn as catalyst metals, the Zn content being 7.5-12.5 mass%; alternatively, Fe, Co, and Al are contained as catalyst metals, and the Al content is 8.5-11.5 mass%.

Description

Technical Field

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

[0002] Heretofore, efforts have been continuously made to mitigate climate change or reduce its impact. To achieve this goal, the exhaust restrictions of automobiles have been further promoted. In particular, it is required to reduce the emissions of carbon dioxide contained in the exhaust gas of internal combustion engines.

[0003] In recent years, a technique 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 containing Cu, Zn, and alumina has been proposed (see Patent Document 1).

[0004] As the fuel obtained by hydrogenating carbon dioxide, it is required to produce hydrocarbons having 5 or more carbon atoms, which can be used as liquid fuels. As such a technique, a method has been proposed in which potassium is used as a promoter for an Fe catalyst in the Fischer-Tropsch (FT) synthesis reaction to prepare highly branched products having 5 or more carbon atoms (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] Incidentally, in the measures to reduce carbon dioxide emissions, the following technique has attracted attention. The technique relates to sustainable aviation fuel (SAF), which is aviation fuel manufactured from biomass-derived raw materials and waste. Preferably, a technique related to the hydrogenation reaction of carbon dioxide can be used to directly manufacture SAF from carbon dioxide. However, the hydrocarbons generated by the technique disclosed in Patent Document 2 have the following problem, that is, the production rate of hydrocarbons having 8 to 16 carbon atoms, which are the main components of SAF, is low.

[0011] In view of the above, the present invention aims to provide a carbon dioxide reduction catalyst 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 that hydrogenates carbon dioxide to reduce carbon dioxide and produce hydrocarbons, and contains Fe, Co, and Zn as catalyst metals, and the content of the aforementioned Zn is 7.5 to 12.5% by mass.

[0014] According to the invention of (1), a carbon dioxide reduction catalyst can be provided, and the carbon dioxide reduction catalyst can preferably produce hydrocarbons having 8 to 16 carbon atoms by the hydrogenation reaction of carbon dioxide.

[0015] (2) In addition, the present invention relates to a carbon dioxide reduction catalyst that hydrogenates carbon dioxide to reduce carbon dioxide and produce hydrocarbons, and contains Fe, Co, and Al as catalyst metals, and the content of the aforementioned Al is 8.5 to 11.5% by mass.

[0016] According to the invention of (2), a carbon dioxide reduction catalyst can be provided, and the carbon dioxide reduction catalyst can preferably produce hydrocarbons having 8 to 16 carbon atoms by the hydrogenation reaction of carbon dioxide.

[0017] (3) According to the carbon dioxide reduction catalyst described in (1) or (2), wherein the carbon dioxide reduction catalyst further contains Na as a catalyst metal, and the content of the aforementioned Na is 0.5 to 1.5% by mass.

[0018] According to the invention of (3), the basicity of the catalyst can be increased, and the adverse effects caused by Na covering the reaction sites can be avoided. Therefore, the generation of by-products is suppressed, and hydrocarbons having 8 to 16 carbon atoms can be better produced.

[0019] (4) A carbon dioxide reduction catalytic device is provided with a second catalyst on the upstream side of the carbon dioxide reduction catalyst described in (1) or (2), and the second catalyst contains at least one of Fe and Ga or Zr as a catalyst metal.

[0020] According to the invention of (4), by the second catalyst, the reverse water gas shift reaction of reducing carbon dioxide to carbon monoxide and the FT synthesis reaction of converting carbon monoxide to hydrocarbons are further carried out, and the carbon number of the hydrocarbons generated by the carbon dioxide reduction catalyst disposed on the downstream side increases. Therefore, hydrocarbons having 8 to 16 carbon atoms can be better produced.

[0021] (5) A method for manufacturing jet fuel includes: a carbon dioxide reduction step of reducing carbon dioxide by the carbon dioxide reduction catalyst described in (1) or (2); and an upgrading step of performing an upgrading treatment on the hydrocarbons obtained by the carbon dioxide reduction step.

[0022] According to the invention of (5), by subjecting the higher hydrocarbons obtained through the carbon dioxide reduction process to a upgrading process, the production rate of hydrocarbons having 8 to 16 carbon atoms is increased, and thus jet fuel can be efficiently produced. Description of the Drawings

[0023] Figure 1 It is a graph showing the relationship between the Al addition amount of the carbon dioxide reduction catalyst of the examples and comparative examples of the present invention and the CO2 conversion rate.

[0024] Figure 2 It is a graph showing the relationship between the Al addition amount of the examples and comparative examples and the C8-C 16 selectivity.

[0025] Figure 3 It is a graph showing the relationship between the Al addition amount of the examples and comparative examples and the C8-C 16 production rate.

[0026] Figure 4A It is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Comparative Example 1.

[0027] Figure 4B It is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Comparative Example 2.

[0028] Figure 4C It is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Example 1.

[0029] Figure 4D It is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Comparative Example 3.

[0030] Figure 5 It is a graph showing the relationship between the Zn addition amount of the examples and comparative examples and the CO2 conversion rate.

[0031] Figure 6 It is a graph showing the relationship between the Zn addition amount of the examples and comparative examples and the C8-C 16 selectivity.

[0032] Figure 7 It is a graph showing the relationship between the Zn addition amount of the examples and comparative examples and the C8-C 16 production rate.

[0033] Figure 8A It is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Comparative Example 5.

[0034] Figure 8B It is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Example 2.

[0035] Figure 8CIt is a graph showing the relationship between the carbon number and the hydrocarbon selectivity of Comparative Example 6.

[0036] Figure 9 It is a diagram showing the structure of the carbon dioxide reduction catalytic device of the first embodiment.

[0037] Figure 10 It is a diagram showing the structure of the carbon dioxide reduction catalytic device of a modified example of the first embodiment.

[0038] Figure 11 It is a diagram showing the structure of the carbon dioxide reduction catalytic device of the second embodiment. Detailed Embodiments

[0039] <Carbon Dioxide Reduction Catalyst>

[0040] <<First Embodiment>>

[0041] The carbon dioxide reduction catalyst of the present embodiment must contain Fe (iron), Co (cobalt), and Zn (zinc) as catalyst metals. In addition, Na (sodium) is preferably further contained. The carbon dioxide reduction reaction using the carbon dioxide reduction catalyst of the present embodiment is a reaction in which a mixed gas of H2 (hydrogen) and CO2 (carbon dioxide) is used as a raw material, and the reverse water gas shift reaction of reducing CO2 to CO (carbon monoxide) and the FT synthesis reaction of converting CO to hydrocarbons are further carried out to produce hydrocarbons. The carbon dioxide reduction catalyst of the present embodiment contributes to both the above-mentioned reverse water gas shift reaction and FT synthesis reaction.

[0042] Fe is contained as a catalyst metal of the carbon dioxide reduction catalyst, and can be a compound such as an oxide, a carbonate compound, a nitrate compound, or a sulfate compound, and is preferably an oxide. Two or more of these compounds may also be contained. In addition, Fe is more preferably contained in the catalyst metal as an Fe-Co composite oxide containing Fe and Co. By using a catalyst metal containing an Fe-Co composite oxide, since Co itself has carbon growth reactivity, the growth of carbon chains can be promoted compared to compounds such as iron oxides.

[0043] The content of Fe is preferably, for example, 65 to 75% by mass in terms of metal atoms in the catalyst metal of the carbon dioxide reduction catalyst.

[0044] Co is contained as a catalyst metal of the carbon dioxide reduction catalyst, and like Fe, can be a compound such as an oxide, a carbonate compound, a nitrate compound, or a sulfate compound, and is preferably an oxide. Two or more of these compounds may also be contained. Co is more preferably contained in the catalyst metal as an Fe-Co composite oxide containing Fe and Co.

[0045] The content of Co is preferably 15 to 25% by mass in terms of metal atoms in the catalyst metal of the carbon dioxide reduction catalyst. By making the content of Co 15% by mass or more, the carbon growth reactivity of Co itself can be exhibited. By making the content of Co 25% by mass or less, the formation of methane as a by-product can be suppressed. In addition, the function of reducing carbon dioxide in the iron catalyst to carbon monoxide (reverse water gas shift reaction) can be maintained.

[0046] Zn is contained as a catalyst metal of the carbon dioxide reduction catalyst and, like Fe, can be a compound such as an oxide, a carbonate compound, a nitrate compound, a sulfate compound, etc., and is preferably an oxide. Zn is more preferably contained in the catalyst metal as an Fe-Co-Zn composite oxide containing Fe and Co.

[0047] By containing Zn while containing Fe and Co in the carbon dioxide reduction catalyst, a spinel-type crystal structure composed of these metals (for example, Zn(FeCo)2O4) can be obtained. Thus, for example, compared with Fe3O4 and (FeCo)3O4 without Zn, the coordination number of Fe with oxygen atoms decreases. In addition, Zn has a lower redox potential than Fe and is easily oxidized. Therefore, it is generally considered that the oxidation of Fe is suppressed and the progress of the redox cycle of FT synthesis is promoted, improving the reactivity.

[0048] The content of Zn is 7.5 to 12.5% by mass in terms of metal atoms in the catalyst metal of the carbon dioxide reduction catalyst. By making the content of Zn 7.5% by mass or more, the formation of lower hydrocarbons such as CH4 is suppressed, and the effect of growing the carbon chain of the produced hydrocarbons is obtained. By making the content of Zn 12.5% by mass or less, the decrease in activity caused by Zn covering the reaction sites of Fe can be suppressed.

[0049] Na functions as a promoter in the catalyst metal. Na is preferably present on the surface of the composite oxide in the form of an oxide or the like, different from the above composite oxide. In addition, the catalyst metal may contain Li, K, Rb, Cs and other alkali metals or contain the alkali metals instead of Na while containing Na.

[0050] In the catalyst metal of the carbon dioxide reduction catalyst, the content of Na is preferably 0.5 to 1.5% by mass, more preferably 1.0% by mass. By making the content of Na 0.5% by mass or more, the basicity 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 making the content of Na 1.5% by mass or less, the adverse effects caused by Na covering the reaction sites of Fe can be avoided, the formation of carbon monoxide as a by-product can be suppressed, and the decrease in catalytic activity can be prevented.

[0051] 《Second Embodiment》

[0052] The carbon dioxide reduction catalyst of this embodiment must contain Fe (iron), Co (cobalt), and Al (aluminum) as catalyst metals. Additionally, it preferably contains Na (sodium). The carbon dioxide reduction reaction using the carbon dioxide reduction catalyst of this embodiment is a reaction that generates hydrocarbons by using a mixed gas of H2 (hydrogen) and CO2 (carbon dioxide) as raw materials, and further performing the reverse water gas shift reaction of reducing CO2 to CO (carbon monoxide) and the FT synthesis reaction of converting CO to hydrocarbons. The carbon dioxide reduction catalyst of this embodiment contributes to both the above-mentioned reverse water gas shift reaction and FT synthesis reaction.

[0053] As the composition of Fe (iron), Co (cobalt), and Na (sodium) among the catalyst metals of this embodiment, the same composition (types of compounds, states, contents, etc.) as in the first embodiment can be adopted.

[0054] By containing Al while containing Fe and Co in the carbon dioxide reduction catalyst, a spinel-type crystal structure composed of these metals (for example, Al(FeCo)2O4) can be obtained. Thus, for example, compared with Fe3O4 and (FeCo)3O4 that do not have Al, the coordination number of Fe with oxygen atoms decreases. In addition, compared with Fe, Al has a lower redox potential and is easily oxidized. Therefore, it is considered that the oxidation of Fe is suppressed, promoting the progress of the redox cycle of FT synthesis and improving the reactivity.

[0055] The content of Al in the catalyst metals of the carbon dioxide reduction catalyst is 8.5 to 11.5% by mass in terms of metal atoms. By making the content of Al 8.5% by mass or more, the generation of lower hydrocarbons such as CH4 is suppressed, and the effect of growing the carbon chain of the generated hydrocarbons is obtained. By making the content of Al 11.5% by mass or less, a decrease in activity caused by Al covering the reaction sites of Fe can be suppressed.

[0056] (Manufacturing Method of Carbon Dioxide Reduction Catalyst)

[0057] The manufacturing method of the carbon dioxide reduction catalyst preferably includes a hydrothermal synthesis step and an impregnation step.

[0058] (Hydrothermal Synthesis Step)

[0059] The hydrothermal synthesis process is a process of extracting a precipitate as a catalyst precursor from an aqueous solution by the hydrothermal synthesis method. The aqueous solution is prepared by dissolving nitrates of Fe, Co, and Zn or Al in a specified amount of an aqueous urea solution. By the hydrothermal synthesis process, an Fe-Co-Zn composite oxide or an Fe-Co-Al composite oxide is formed. In the hydrothermal synthesis process, it is preferable to obtain a precipitate solution by a hydrothermal synthesis process using an autoclave for the above aqueous solution containing Fe, Co, and Zn or Al. Thereafter, the precipitate is separated from the precipitate solution by filtration / washing, etc. and dried, whereby a precipitate (Fe-Co-Zn composite oxide or Fe-Co-Al composite oxide) as a catalyst precursor is obtained.

[0060] (Impregnation process)

[0061] The impregnation process is a process of dropping an aqueous solution containing Na into the precipitate obtained by the hydrothermal synthesis process, drying for a specified time, and calcining the obtained powder at a specified temperature. By the impregnation process, the Na compound can be biased near the surface of the above composite oxide. As the aqueous solution containing Na, for example, an aqueous NaNO3 solution can be cited. The aqueous NaNO3 solution can be dropped under ultrasonic vibration. Thereby, the Na compound can be uniformly biased near the surface of the above composite oxide. The calcination temperature can be set to 550 °C, for example, and the calcination time can be set to 4 hours.

[0062] <Carbon dioxide reduction catalytic device>

[0063] <<First Embodiment>>

[0064] As Figure 9 shown, the carbon dioxide reduction catalyst C2 of the above embodiment preferably has a second catalyst C1 disposed on the upstream side. The second catalyst C1 contains at least one of Fe and Ga or Zr as a catalyst metal. The carbon dioxide reduction catalyst C2 and the second catalyst C1 are disposed in catalytic reactors 30 and 20, respectively, and connected by a flow path L and used as a carbon dioxide reduction catalytic device 1.

[0065] (Second catalyst)

[0066] The second catalyst C1 must contain Fe (iron) as the catalyst metal and contain at least one of Ga (gallium) or Zr (zirconium). Additionally, it is preferably further contained Na (sodium). The carbon dioxide reduction reaction using the second catalyst C1 of the present embodiment is a reaction that generates hydrocarbons by using a mixed gas of H2 (hydrogen) and CO2 (carbon dioxide) as a raw material and further performing the reverse water-gas shift reaction of reducing CO2 to CO (carbon monoxide) and the FT synthesis reaction of converting CO to hydrocarbons. The catalyst of the present embodiment contributes to both the above-mentioned reverse water-gas shift reaction and FT synthesis reaction.

[0067] The Fe contained in the catalyst metal of the second catalyst C1 can be a compound such as an oxide, carbonate compound, nitrate compound, sulfate compound, etc., and is preferably an oxide. These compounds can also contain two or more. Additionally, Fe is more preferably contained in the catalyst metal as at least one of an Fe-Ga composite oxide containing Fe and Ga and an Fe-Zr composite oxide containing 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 further carbide in the FT synthesis reaction, thereby promoting the CH2 growth reaction in the catalyst and promoting the growth of the carbon chain.

[0068] The content of Fe in the catalyst metal of the second catalyst C1 is preferably 55 to 90% by mass in terms of metal atoms, and more preferably 60 to 75% by mass.

[0069] Similar to Fe, the Ga contained in the catalyst metal of the second catalyst C1 can be a compound such as an oxide, carbonate compound, nitrate compound, sulfate compound, etc., and is preferably an oxide. These compounds can also contain two or more. Ga is more preferably contained in the catalyst metal as an Fe-Ga composite oxide containing Fe and Ga.

[0070] The content of Ga in the catalyst metal of the second 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 making the content of Ga 30% by mass or less, the adverse effects caused by the reaction sites where Ga coats Fe can be avoided, and the decrease in catalytic activity can be prevented.

[0071] Similar to Fe, the Zr contained in the catalyst metal of the second catalyst C1 can be a compound such as an oxide, carbonate compound, nitrate compound, sulfate compound, etc., and is preferably an oxide. These compounds can also contain two or more. Zr is more preferably contained in the catalyst metal as an Fe-Zr composite oxide containing Fe and Zr.

[0072] The catalyst metal of the second catalyst C1 may also contain both Ga and Zr. When both Ga and Zr are included in the catalyst metal, these catalyst metals are more preferably included in the catalyst metal as an Fe-Ga-Zr composite oxide containing Fe, Zr, and Ga. Compared with compounds such as iron oxide, the Fe-Ga-Zr composite oxide is micronized, so the reaction sites of the Fe catalyst increase, thereby ensuring the reaction time of the Fischer-Tropsch synthesis reaction, that is, the time for the carbon chain growth of the produced hydrocarbons.

[0073] As the composition of Na (sodium) among the catalyst metals of the second catalyst C1, the same composition (type of compound, state, content, etc.) as that of the carbon dioxide reduction catalyst in the above embodiment can be adopted.

[0074] (Catalytic reactor)

[0075] As the structure of the catalytic reactors 20 and 30 for disposing the carbon dioxide reduction catalyst C2 and the second catalyst C1 of the above embodiment, there is no particular limitation, and a known structure can be applied. For example, a fixed-bed flow-through reaction device in which a powdery, particulate, or granular catalyst and a carrier supporting the catalyst are filled in a flow path having a specified shape can be cited.

[0076] (Water trap section)

[0077] Next, use Figure 10 To illustrate the structure of a modified example of the carbon dioxide reduction catalytic device 1 of the above first embodiment, that is, the carbon dioxide reduction catalytic device 1a. In the following description, for the same structure as that of the first embodiment, the same reference numerals may be sometimes marked in the drawings and the description may be omitted. The carbon dioxide reduction catalytic device 1a is preferably as Figure 10 Shown, a dehydration section 40 is connected to the flow path L connecting the catalytic reactors 20 and 30 to each other. The dehydration section 40 removes water from the fluid supplied to the carbon dioxide reduction catalyst. Thereby, in the catalytic reaction by the carbon dioxide reduction catalyst, the chemical equilibrium can be shifted in the direction of increasing the carbon number of the hydrocarbons. Therefore, the yield of hydrocarbons having 8 to 16 carbon atoms can be increased.

[0078] 《Second Embodiment》

[0079] Next, use Figure 11 To illustrate the structure of the carbon dioxide reduction catalytic device 1b of the second embodiment of the present invention. The carbon dioxide reduction catalytic device 1b is as Figure 11 Shown, a upgrading device 40 is disposed at the rear stage of the catalytic reactor 30.

[0080] (Upgrading device)

[0081] The upgrading device 40 is a device for upgrading low-quality fractions such as cracked light oil of hydrocarbons obtained by the carbon dioxide reduction reaction in the catalytic reactors 20 and 30. As the upgrading device 40, a known heavy oil cracking device such as a fluid catalytic cracking (FCC) unit can be used.

[0082] (Method for manufacturing the second catalyst)

[0083] The method for manufacturing the second catalyst of the present embodiment preferably includes a coprecipitation step and an impregnation step.

[0084] (Coprecipitation step)

[0085] The coprecipitation step is a step of extracting a precipitate as a catalyst precursor from an aqueous solution by coprecipitation. The aqueous solution is prepared by dissolving at least one of a nitrate of Fe, a nitrate of Ga, and a nitrate of Zr in a predetermined amount of distilled water. By the coprecipitation step, at least one of an Fe-Ga composite oxide, an Fe-Zr composite oxide, and an Fe-Ga-Zr composite oxide is formed. Preferably, in the coprecipitation step, an aqueous urea solution is added dropwise to the above aqueous solution containing Fe and at least one of Ga and Zr to obtain a precipitate solution. Thereafter, the precipitate is separated from the precipitate 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.

[0086] (Impregnation step)

[0087] The impregnation step can adopt the same steps as the impregnation step in the method for manufacturing the carbon dioxide reduction catalyst described above.

[0088] <Method for manufacturing jet fuel>

[0089] The method for manufacturing jet fuel using the above carbon dioxide reduction catalyst will be described below. The carbon dioxide reduction method includes: a carbon dioxide reduction step of reducing carbon dioxide by the above carbon dioxide reduction catalyst; and an upgrading step of upgrading the hydrocarbon obtained by the carbon dioxide reduction step.

[0090] The carbon dioxide reduction process is carried out, for example, using the above-mentioned catalytic reactors 20 and 30. The carbon dioxide reduction process includes, for example: a second catalytic reaction process in which a gas containing carbon dioxide is brought into contact with a second catalyst C1 disposed on the upstream side; and a carbon dioxide reduction catalytic reaction process in which a gas containing hydrocarbons generated by the above-mentioned second catalytic reaction process is brought into contact with a carbon dioxide reduction catalyst C2 disposed on the downstream side to increase the carbon number. It is also possible to include the following process between the second catalytic reaction process and the carbon dioxide reduction catalytic reaction process: removing moisture from the gas containing hydrocarbons generated by the above-mentioned second catalytic reaction process by means of a dehydration unit 40.

[0091] The catalytic temperature T2 of the carbon dioxide reduction catalyst C2 in the carbon dioxide reduction catalytic reaction process is preferably lower than the catalytic temperature T1 of the second catalyst C1 in the second catalytic reaction process. Thereby, the activity of Co contained in the carbon dioxide reduction catalyst can be controlled, and the yield of hydrocarbons having 8 to 16 carbon atoms can be further increased.

[0092] The catalytic temperature T1 is, for example, preferably set to 340 to 400 °C, and the catalytic temperature T2 is, for example, preferably set to 260 to 340 °C.

[0093] In addition to the above, the carbon dioxide reduction process may also be a process of generating hydrocarbons using only the above-mentioned carbon dioxide reduction catalyst.

[0094] The upgrading process is a process of upgrading low-quality fractions such as cracked light oil of hydrocarbons obtained by the carbon dioxide reduction process to obtain jet fuel. As the upgrading treatment, a known heavy oil cracking device such as a fluid catalytic cracking unit (FCC) can be used.

[0095] The present invention is not limited to the above-described embodiments, and variations and improvements within the scope capable of achieving the object of the present invention are included in the present invention.

[0096] Examples

[0097] Next, examples of the present invention will be described, but the present invention is not limited to these examples.

[0098] <Example 1>

[0099] [Production of Carbon Dioxide Reduction Catalyst]

[0100] In terms of metal atom conversion, weigh the nitrate of Fe (Fe(NO3)3·9H2O), which is the catalyst metal of the carbon dioxide reduction catalyst C2, the nitrate of Co (Co(NO3)2·6H2O), which is also the catalyst metal, and the nitrate of Al (Al(NO3)3·9H2O), which is also the catalyst metal, in such a way that the mass ratio of Fe:Co:Al is 67.5:22.5:10, and dissolve them in urea water. Then, after stirring the above aqueous solution for 1 hour, transfer it to an autoclave container and hydrothermally synthesize it at 120 °C for 12 hours to obtain a precipitate solution containing Fe, Co, and Al as precipitates. Then, at room temperature, after aging the precipitate solution for 24 hours, filter and wash it repeatedly to separate the precipitate. Dry the separated precipitate at 60 °C for 12 hours to obtain the Fe-Co-Al catalyst precursor.

[0101] For the above Fe-Co-Al catalyst precursor, under ultrasonic vibration at 92 kHz, dropwise add an aqueous solution of NaNO3 so that the Na content becomes 1.0% by mass. Then, dry it under a vacuum of 5000 Pa for 1 hour, and further dry it at 60 °C under normal pressure for 12 hours to obtain a powder. Calcinate the obtained powder at 550 °C for 4 hours to obtain the carbon dioxide reduction catalyst C2 of Example 1. The content of Al in the catalyst metal is 10% by mass.

[0102] [Preparation of the second catalyst]

[0103] In terms of metal atom conversion, weigh the nitrate of Fe (Fe(NO3)3·9H2O), which is the catalyst metal of the second catalyst C1, the nitrate of Zr (ZrO(NO3)2·2H2O), which is also the catalyst metal, and the nitrate of Ga (Ga(NO3)3·6H2O), which is also the catalyst metal, in such a way that the mass ratio of Fe:Zr:Ga is 6:1:3, and dissolve them in distilled water. Then, while stirring the above aqueous solution, dropwise add an aqueous solution of CH4N2O at 2 ml / min and fix the pH at 8.5 to obtain a precipitate solution containing Fe, Zr, and Ga as precipitates. Then, at room temperature, after aging the precipitate solution for 24 hours, filter and wash it repeatedly to separate the precipitate. Dry the separated precipitate at 60 °C for 12 hours to obtain the Fe-Ga-Zr catalyst precursor.

[0104] For the above Fe-Ga-Zr catalyst precursor, an aqueous solution of NaNO3 was added dropwise under ultrasonic excitation at 92 kHz in such a manner that the Na content became 1.0% by mass. Subsequently, it was dried under a vacuum of 5000 Pa for 1 hour, and then further dried at 60 °C for 12 hours under normal pressure to obtain a powder. The obtained powder was calcined at 550 °C for 4 hours to thereby obtain the second catalyst C1 of Example 1.

[0105] [Fabrication of Carbon Dioxide Reduction Catalytic Device]

[0106] Using the carbon dioxide reduction catalyst C2 and the second catalyst C1 obtained above, a carbon dioxide reduction catalytic device 1a was fabricated. Fixed-bed flow-through reaction devices were used for the catalytic reactors 20 and 30, and 0.25 g of a particulate material with a side length of 0.4 - 0.8 mm was used as the carbon dioxide reduction catalyst C2. The above particles were filled in a reaction tube (inner diameter 6 mm) with a length of 5 cm for use. The second catalyst also had the same shape, weight, and filling amount. In addition, a dehydration unit 40 was provided on the flow path L connecting the catalytic reactors 20 and 30 to each other. The reaction temperature was such that the catalytic temperature T1 of the second catalyst was set to 380 °C, and the catalytic temperature T2 of the carbon dioxide reduction catalyst was set to 300 °C.

[0107] <Example 2>

[0108] In the carbon dioxide reduction catalyst C2, nitrate of Zn (Zn(NO3)2·6H2O) as the catalyst metal was used instead of nitrate of Al as the catalyst metal, and otherwise it was the same as in Example 1.

[0109] <Comparative Example 1>

[0110] In the carbon dioxide reduction catalyst C2, nitrate of Al as the catalyst metal was not used, and otherwise it was the same as in Example 1.

[0111] <Comparative Examples 2 - 4>

[0112] In the carbon dioxide reduction catalyst C2, the amount of nitrate of Al was adjusted such that the content of Al as the catalyst metal was 5% by mass (Comparative Example 2), 15% by mass (Comparative Example 3), and 20% by mass (Comparative Example 4) respectively, and otherwise it was the same as in Example 1. In addition, as the content of Al increased or decreased, the contents of Fe and Co were increased or decreased in accordance with the ratio of Fe:Co = 3:1 in terms of metal atom conversion.

[0113] <Comparative Examples 5 - 7>

[0114] In the carbon dioxide reduction catalyst C2, the amount of zinc nitrate was adjusted such that the content of zinc as the catalyst metal was 5% by mass (Comparative Example 5), 15% by mass (Comparative Example 6), and 20% by mass (Comparative Example 7), respectively. Otherwise, it was the same as in Example 2. In addition, as the content of zinc increased or decreased, the contents of iron and cobalt were increased or decreased in a ratio of Fe:Co = 3:1 in terms of metal atoms.

[0115] [Evaluation]

[0116] Using the carbon dioxide reduction catalytic devices of the above respective Examples and Comparative Examples, the carbon dioxide reduction reaction was carried out by the following method. The reaction gas was set to CO2 0.28 NL / h and H2 0.84 NL / h (CO2 / H2 = 1 / 3). Let W / F (catalyst weight / gas flow rate) be 5.0 g·h / mol, and the space velocity SV (Space Velocity) = 5,000 h -1 . The pressure was set to 3 MPa, and the reaction time was 4 hours. Qualitative / quantitative analysis of the gas components after the catalytic reaction was carried out by an on-line gas chromatograph (Shimadzu, GC-2014AT, detector: thermal conductivity detector (TCD)) and a flame ionization detector (FID) (Shimadzu, GC-2014AF). In addition, qualitative / quantitative analysis of the liquid components after the catalytic reaction was also carried out by an off-line gas chromatograph (Shimadzu, GC-2014AF, detector: flame ionization detector (FID)).

[0117] (CO2 conversion rate)

[0118] The conversion rate of the above carbon dioxide reduction reaction to CO2 was calculated by the following formula (1). The results are shown in Figure 1 and Figure 5 .

[0119] CO2 conversion rate (%) = ((CO2 concentration before reaction) - (CO2 concentration after reaction)) / (CO2 concentration before reaction) × 100 ··· (1)

[0120] (C8 - 16 selectivity)

[0121] The selectivity of hydrocarbons having 8 to 16 carbon atoms (C8 - 16 ) produced by the above carbon dioxide reduction reaction was calculated by the following formula (2). The results are shown in Figure 2 and Figure 6 . In addition, the selectivity of hydrocarbons having each carbon number was calculated by the same method as the following formula (2). The results are shown in Figures 4A to 4D , andFigures 8A to 8C 。

[0122] C8- 16 Selectivity (%) = (C8- 16 Concentration of the contained component) / ((CO2 concentration before the reaction) - (CO2 concentration after the reaction)) × 100 ··· (2)

[0123] Figure 4A is a graph showing the carbon number of the hydrocarbons produced by the carbon dioxide reduction catalytic device of Comparative Example 1 and the selectivity of the hydrocarbons of each carbon number. Similarly, it is Figure 4B corresponding to Comparative Example 2, Figure 4C corresponding to Example 1, Figure 4D a graph corresponding to Comparative Example 2. Comparing Figure 4A with Figure 4B , by setting the content of Al to 0 mass% to 5 mass%, the hydrocarbons with 1 carbon atom grow into hydrocarbons with 2 or more carbon atoms. On the other hand, the selectivity of the hydrocarbons with 8 to 16 carbon atoms does not change significantly. In Figure 4C , when the content of Al is 10 mass%, the selectivity of the hydrocarbons with 8 to 16 carbon atoms increases. In Figure 4D , when the content of Al is 15 mass%, the selectivity of the hydrocarbons with 1 carbon atom increases, and the selectivity of the hydrocarbons with 8 to 16 carbon atoms decreases.

[0124] Similarly to the above, it is Figure 8A corresponding to Comparative Example 5, Figure 8B corresponding to Example 2, Figure 8C a graph corresponding to Comparative Example 6. Comparing Figure 4A with Figure 8A , by setting the content of Zn to 0 mass% to 5 mass%, the hydrocarbons with 1 carbon atom grow into hydrocarbons with 2 or more carbon atoms. On the other hand, the selectivity of the hydrocarbons with 8 to 16 carbon atoms does not change significantly. In Figure 8B , when the content of Zn is 10 mass%, the selectivity of the hydrocarbons with 8 to 16 carbon atoms increases. In Figure 8C , when the content of Zn is 15 mass%, the selectivity of the hydrocarbons with 1 carbon atom increases, and the selectivity of the hydrocarbons with 8 to 16 carbon atoms decreases.

[0125] (C8- 16 Generation rate (yield))

[0126] The generation rate of the hydrocarbons with 8 to 16 carbon atoms (C8- 16 ) produced by the above carbon dioxide reduction reaction was obtained by the following formula (3). The results are shown in Figure 3 and Figure 7 .

[0127] C8- 16 Generation rate (%) = CO2 conversion rate × C8-16 Selectivity / 100... (3)

[0128] In Figure 3 for C8 with Al contents of 5, 10, 15, and 20 mass%, 16 the production rate was subjected to least - squares approximation. The obtained approximation formula is shown in the following formula (4).

[0129] (Production rate of C8 - 16 ) = 0.0179x 3 − 0.8129x 2 + 10.817x − 22.246... (4)

[0130] In the above formula (4), x refers to the Al content (mass%). According to the above formula (4), the Al content in the catalyst metal with a higher C8 - 16 production rate (%) than that of Comparative Example 1 with an Al content of 0 mass% was calculated to be 8.5 - 11.5 mass%. 16

[0131] In Figure 7 for C8 with Zn contents of 5, 10, and 15 mass%, 16 the production rate was subjected to least - squares approximation. The obtained approximation formula is shown in the following formula (5).

[0132] (Production rate of C8 - 16 ) = − 0.2503x 2 + 5.0524x − 1.8381... (5)

[0133] In the above formula (5), x refers to the Zn content (mass%). According to the above formula (5), the Zn content in the catalyst metal with a higher C8 - 16 production rate (%) than that of Comparative Example 1 with a Zn content of 0 mass% was calculated to be 7.5 - 12.5 mass%. 16

[0134] As Figure 3 and Figure 7 shown, the following results can be known: Compared with the carbon dioxide reduction catalytic devices of each comparative example, the carbon dioxide reduction catalytic devices of each example have a higher C8 - 16 production rate (yield). In addition, in Figure 3 and Figure 7 , it can be known that by making the Al content 8.5 - 11.5 mass% and the Zn content 7.5 - 12.5 mass% respectively, a high C8 - 16 production rate (yield) can be obtained.​​

Claims

1. A carbon dioxide reduction catalyst that causes a carbon dioxide hydrogenation reaction to reduce carbon dioxide and generate hydrocarbons, and Contains Fe, Co and Zn as catalyst metals, The Zn content is 7.5 to 12.5 mass %.

2. A carbon dioxide reduction catalyst that causes a carbon dioxide hydrogenation reaction to reduce carbon dioxide and generate hydrocarbons, and Contains Fe, Co and Al as catalyst metals, The Al content is 8.5 to 11.5 mass %.

3. The carbon dioxide reduction catalyst according to claim 1 or 2, wherein The carbon dioxide reduction catalyst further comprises Na as a catalyst metal, The content of Na is 0.5 to 1.5 mass %. 4 . A carbon dioxide reduction catalyst device, comprising: a second catalyst disposed on an upstream side of the carbon dioxide reduction catalyst according to claim 1 , wherein the second catalyst contains Fe and at least one of Ga and Zr as a catalyst metal.

5. A method for producing jet fuel, comprising: a carbon dioxide reduction step, reducing carbon dioxide using the carbon dioxide reduction catalyst according to claim 1 or 2; and The upgrading step is to upgrade the hydrocarbons obtained in the carbon dioxide reduction step.

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