Hydrocarbon production catalyst and hydrocarbon production method

Abstract

To provide a highly active hydrocarbon production catalyst that can increase the productivity of LPG consisting of propane and butane in hydrocarbon production using carbon oxide and hydrogen as raw materials, and a method for producing hydrocarbons using the hydrocarbon production catalyst. [Solution] A hydrocarbon production catalyst comprising a first catalyst layer containing catalyst A containing iron, cobalt, aluminum, and sodium, and a second catalyst layer laminated on the first catalyst layer and containing zeolite having a molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) of 150 or less, and a method for producing hydrocarbons using the hydrocarbon production catalyst.

Description

【Technical Field】 【0001】 The present invention relates to a hydrocarbon production catalyst and a method for producing hydrocarbons. 【Background Art】 【0002】 In recent years, due to the emergence of environmental problems such as global warming, the reduction of carbon dioxide emissions has been demanded. Therefore, carbon recycling technology that separates and recovers carbon dioxide and effectively utilizes it as a resource can contribute to the reduction of carbon dioxide emissions. On the other hand, hydrocarbons can be utilized as various fuels. One of them, LPG (Liquefied Petroleum Gas) consisting of propane and butane, has a high demand due to its high portability and storage stability. 【0003】 Under such circumstances, research and development for producing LPG by Fischer-Tropsch (FT) synthesis reaction using carbon dioxide and hydrogen as raw materials have been actively conducted. 【0004】 For example, Patent Document 1 discloses "a carbon dioxide reduction catalyst containing Na and Fe as catalytic metals and a porous solid catalyst with pores enlarged by alkali treatment". Non-Patent Document 1 discloses "a catalyst obtained by mixing a K-Fe / C catalyst and ZSM-5". 【Prior Art Documents】 【Patent Documents】 【0005】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2023-146025 【Non-Patent Documents】 【0006】 【Non-Patent Document 1】 Lisheng Guo, et al. "Boosting liquid hydrocarbons selectivity from CO2hydrogenation by facilely tailoring surface acid properties of zeolite via a modified Fischer-Tropsch synthesis" Fuel, Vol. 306, 121684, 15.12.2021 [Disclosure of the Invention] [Problems that the invention aims to solve] 【0007】 In the production of hydrocarbons using carbon dioxide and hydrogen as raw materials, including in Patent Document 1, it is common to use iron-based catalysts due to the high conversion rate of carbon dioxide. However, a challenge with iron-based catalysts is that the proportion of olefins in the hydrocarbons produced is high, resulting in low productivity of LPG, which is a type of paraffin. In particular, the catalyst evaluated in Non-Patent Document 1 exhibits a relatively high paraffin selectivity, but has a low carbon dioxide conversion rate, resulting in low overall LPG productivity. Therefore, in hydrocarbon production using carbon dioxide and hydrogen as raw materials, there is room for improvement in hydrocarbon production catalysts that efficiently produce LPG. 【0008】 Therefore, the object of the present invention is to provide a highly active hydrocarbon production catalyst that can increase the productivity of LPG consisting of propane and butane in hydrocarbon production using carbon dioxide and hydrogen as raw materials, and a method for producing hydrocarbons using the hydrocarbon production catalyst. [Means for solving the problem] 【0009】 The means for solving the problem include the following aspects: <1> A first catalyst layer containing catalyst A, which contains iron, cobalt, aluminum, and sodium, A second catalyst layer is laminated on the first catalyst layer and contains a zeolite in which the molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) is 150 or less, A hydrocarbon production catalyst. <2> In the zeolite, the molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) is 50 or less. <1> A hydrocarbon manufacturing catalyst as described above. <3> The mass ratio of the zeolite to the catalyst A is 0.5 to 3.0. <1> or <2> A hydrocarbon manufacturing catalyst as described above. <4> The aforementioned zeolite is H-ZSM-5 zeolite. <1> ~ <3> A hydrocarbon production catalyst as described in any one of the items. <5> <1> ~ <4> A method for producing hydrocarbons using a hydrocarbon production catalyst described in any one of the items, A method for producing hydrocarbons, comprising contacting a mixed gas containing carbon dioxide and hydrogen with the hydrocarbon production catalyst to produce hydrocarbons. [Effects of the Invention] 【0010】 According to the present invention, it is possible to provide a highly active hydrocarbon production catalyst that can increase the productivity of LPG consisting of propane and butane in hydrocarbon production using carbon dioxide and hydrogen as raw materials, and a method for producing hydrocarbons using the hydrocarbon production catalyst. [Modes for carrying out the invention] 【0011】 The present invention will be described below. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In numerical ranges described in stages, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Within a numerical range, the upper or lower limit stated within that range may be replaced with the value shown in the example. When there are multiple substances corresponding to each component in the composition, unless otherwise specified, the amount of each component in the composition means the total amount of the above-mentioned multiple substances present in the composition. The term "step" includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step is achieved. "Combination of preferred embodiments" is a more preferred embodiment. 【0012】 In addition, "room temperature" refers to a temperature within the range of 23°C ± 3°C. In addition, the "hydrocarbon production catalyst" is also simply referred to as "catalyst". 【0013】 <Hydrocarbon production catalyst> The hydrocarbon production catalyst of the present invention includes a first catalyst layer containing catalyst A containing iron, cobalt, aluminum, and sodium, and a second catalyst layer laminated on the first catalyst layer and containing zeolite with a molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) of 150 or less. 【0014】 Due to the above structure, the catalyst of the present invention becomes a highly active catalyst capable of increasing the productivity of LPG composed of propane and butane in the production of hydrocarbons using carbon dioxide and hydrogen as raw materials. The reason is speculated as follows. 【0015】 In catalyst A of the first catalyst layer, in addition to iron, by containing cobalt, aluminum, and sodium as promoters, the chain growth of hydrocarbons is promoted, and the yield of hydrocarbons having 3 to 4 carbon atoms is increased. In particular, cobalt as a promoter acts as an active site in addition to the active sites of iron, promoting the reaction, and the hydrocarbons produced by cobalt with high hydrogenation ability shift to the short-chain side. In addition, aluminum as a promoter promotes the reaction of raw materials by improving the dispersibility of iron, which is an active site. In addition, when cobalt, aluminum, and sodium are present as co-catalysts, the formation of iron carbide, which is the active species in the FT synthesis reaction, is promoted in a carbon dioxide and hydrogen atmosphere, improving the conversion rate of carbon dioxide and consequently increasing the yield of hydrocarbons with 3 to 4 carbon atoms. On the other hand, the zeolite used as a catalyst in the second catalyst layer converts the olefin produced by catalyst A into paraffin via acid sites, thereby increasing the paraffin selectivity of the product. 【0016】 Therefore, it is presumed that the catalyst of the present invention will be a highly active catalyst that can increase the productivity of LPG, which consists of propane and butane, in hydrocarbon production using carbon dioxide and hydrogen as raw materials. 【0017】 The details of the catalyst of the present invention will be described below. 【0018】 (first catalyst layer) -Catalyst A- The first catalyst layer contains catalyst A. The first catalyst layer may also contain other components in addition to catalyst A. However, the proportion of catalyst A in the first catalyst layer should be, for example, 80% by mass or more (preferably 90% by mass or more, more preferably 95% by mass or more). 【0019】 Catalyst A contains iron, cobalt, aluminum, and sodium. Catalyst A, for example, has sodium supported on an iron, cobalt, and aluminum catalyst support. However, catalyst A may contain small amounts of impurities other than iron, cobalt, aluminum, and sodium. Here, in catalyst A, the iron content is, for example, 30% by mass or more (preferably 45% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more) relative to the total components of the catalyst excluding oxygen. The number of moles or mass of each component (iron, cobalt, aluminum, sodium, and impurities) contained in the catalyst is measured by ICP-AES after the catalyst has undergone pretreatment such as acid decomposition or alkali fusion. 【0020】 The molar percentage of cobalt relative to iron is preferably 0.1 to 120.0%. When the molar percentage of cobalt is 0.1% or higher, the activity of cobalt itself as an active site increases, and the hydrocarbons produced by cobalt, which has high hydrogenation potential, shift to the shorter chain side, making it easier to produce hydrocarbons with 3 to 4 carbon atoms. When the molar percentage of cobalt is 120.0% or less, the relative decrease in the content of iron, which is an active species, is suppressed. In addition, stable iron-cobalt compounds are less likely to form, and the inhibition of FT reaction active site formation is suppressed. Therefore, when the molar percentage of cobalt is within the above range, the catalyst is more easily activated, and the carbon dioxide conversion rate and the productivity of hydrocarbons with 3 to 4 carbon atoms tend to improve. The lower limit of the molar percentage of cobalt relative to iron is more preferably 1.0% or more, 5.0% or more, 8.0%, or 10.0% or more. While a higher molar percentage of cobalt relative to iron improves the productivity of hydrocarbons with 3 to 4 carbon atoms, the increased cobalt content raises catalyst costs. Therefore, the upper limit of the molar percentage of cobalt is more preferably 55.0% or less, 50.0% or less, 20% or less, or 15% or less. 【0021】 The molar percentage of aluminum relative to iron is preferably 0.1 to 20.0%. When the molar percentage of aluminum is 0.1% or higher, the aluminum acts as a co-catalyst, increasing the dispersion of iron, which is the active site, and thus accelerating the reaction of the raw materials. When the molar percentage of aluminum is 20.0% or less, the relative decrease in the content of iron, which is an active species, is suppressed. Therefore, when the molar percentage of aluminum is within the above range, the catalyst is more easily activated, and the carbon dioxide conversion rate and the productivity of hydrocarbons with 3 to 4 carbon atoms tend to improve. The lower limit of the molar percentage of aluminum relative to iron is preferably 1.0% or more, or more preferably 2.0% or more. The upper limit for the molar percentage of aluminum relative to iron is preferably 15.0% or less, or more preferably 12.0% or less. 【0022】 The molar percentage of sodium relative to iron is preferably 0.01 to 0.30%. It is estimated that when the molar percentage of sodium is 0.01% or higher, the basicity of the catalyst surface improves, promoting the formation of iron carbide, which is presumed to be an active species of iron, and promoting the adsorption of carbon dioxide, the raw material gas, onto the catalyst surface. When the molar percentage of sodium is 0.30% or less, the relative decrease in the content of iron, which is an active species, is suppressed. Therefore, when the molar percentage of sodium is within the above range, the catalyst is more easily activated, and the carbon dioxide conversion rate and the productivity of hydrocarbons with 3 to 4 carbon atoms tend to improve. The lower limit of the molar percentage of sodium relative to iron is preferably 0.02% or higher, or more preferably 0.03% or higher. The upper limit for the molar percentage of sodium relative to iron is more preferably 0.20% or less, 0.15% or less, 0.8% or less, or 0.05%. 【0023】 Here, iron, cobalt, aluminum, and sodium are considered to exist in the form of oxides in the catalyst, but the number of moles of each component is calculated based on the total amount of each metal component in all chemical forms. 【0024】 In catalyst A, iron, cobalt, aluminum, and sodium exist mainly as oxides when the catalyst is calcined (unreduced) using the catalyst manufacturing method described later, but mainly as metallics when the catalyst is reduced. Furthermore, depending on the manufacturing conditions, usage conditions, and storage conditions, metals and oxides may be mixed and their proportions may change. 【0025】 Catalyst A does not need to exist solely in a metallic state, as iron, cobalt, aluminum, and sodium are reduced to metallization during the reaction by the reducing atmosphere, even if they are present as oxides, and thus perform the necessary catalytic function. Note that trace amounts of the raw materials (precursors) may remain in the catalyst. 【0026】 -Method for producing catalyst A- The method for producing catalyst A is not particularly limited, but examples include hydrothermal synthesis, coprecipitation, homogeneous precipitation, sol-gel method, and flux method. Among these, the method for producing catalyst A using a precipitation method is preferred. 【0027】 Specifically, the method for manufacturing catalyst A is: The first step involves obtaining a catalyst support containing iron, cobalt, and aluminum by precipitation, The second step involves supporting sodium on the surface of the catalyst support by impregnation, A method for producing hydrocarbon catalysts is provided, which includes having the above characteristics. This catalyst manufacturing method yields a highly active hydrocarbon production catalyst that can significantly increase the productivity of LPG, particularly LPG composed of propane and butane. 【0028】 --First step-- In the first step, a catalyst support containing iron, cobalt, and aluminum is obtained. Specifically, in the first step, a mixture of iron compounds, cobalt compounds, and aluminum compounds, which serve as raw materials (precursors), is brought into contact with a base to obtain a precipitate. The obtained precipitate is then washed, dried, and calcined to obtain a metal oxide to serve as a catalyst support. 【0029】 Either homogeneous precipitation or coprecipitation is acceptable as the precipitation method. The homogeneous precipitation method is a precipitation method that uses urea as a precipitant. In the homogeneous precipitation method, an aqueous solution of a metal precursor and urea is heated, and the ammonia gas generated by the hydrolysis of urea acts as a base to obtain a precipitate. In the coprecipitation method, a precipitate is obtained by dropwise contact between an aqueous solution of a metal precursor and an aqueous solution of a base, while maintaining a constant pH. There are no restrictions on the base, but examples include sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide. 【0030】 In the precipitation method, iron compounds, cobalt compounds, and aluminum compounds used as raw materials (precursors) are all subjected to drying and reduction treatment of the precipitate after precipitation, or drying, calcination and reduction treatment, when counterions (for example, in the case of iron nitrate, (NO3) in Fe(NO3)2) - There are no particular restrictions on the compound as long as it is a compound that volatilizes and is soluble in a solvent. Specifically, iron compounds, cobalt compounds, and aluminum compounds can be used in the form of nitrates, carbonates, acetates, chlorides, acetylacetonates, etc. Alternatively, hydrates of nitrates, carbonates, acetates, and chlorides may be used for iron compounds, cobalt compounds, and aluminum compounds. From the viewpoint of reducing manufacturing costs and ensuring a safe manufacturing environment, it is preferable to use water-soluble compounds for the iron, cobalt, and aluminum compounds, which can be used in aqueous solutions during the precipitation process. In particular, using iron nitrate or iron acetate as the iron compound, cobalt compound, and aluminum compound is preferable because they readily convert to iron oxide during calcination, and subsequent reduction treatment of iron oxide, cobalt oxide, and aluminum oxide is also easy. 【0031】 --Second step-- In the second step, sodium is supported on the surface of the catalyst support obtained in the first step by impregnation. Specifically, in the second step, for example, the obtained catalyst support (oxide) is impregnated with an aqueous solution of a sodium compound as a raw material (precursor), dried and calcined in a vacuum atmosphere, and sodium is supported on the surface of the catalyst support (oxide). 【0032】 Here, the method for supporting sodium on the catalyst is not limited to the impregnation method, but may also be well-known treatment methods such as the incipient wetness method, precipitation method, or ion exchange method. However, since it is preferable to support sodium on the surface of the catalyst (i.e., to support sodium on the surface of the oxide), the impregnation method and the ion exchange method are preferred as methods for supporting sodium on the catalyst support, with the impregnation method being more preferable. When employing the impregnation method to support sodium on the surface of a catalyst support (oxide), it is preferable to irradiate the catalyst support (oxide) with ultrasound after the support operation and before drying or calcination, as this allows the sodium to be uniformly supported on the catalyst support (oxide). Furthermore, during drying after the support operation, drying under a vacuum atmosphere is preferable because it allows the sodium to disperse into the pores of the catalyst support (oxide). 【0033】 As for sodium compounds used as raw materials (precursors), when drying and / or calcining treatments are performed after loading, counterions (for example, in the case of sodium nitrate, (NO3) in NaNO3) - There are no particular restrictions on the compound as long as it is a compound that volatilizes and is soluble in a solvent. Specifically, suitable sodium compounds include nitrates, carbonates, acetates, chlorides, and acetylacetonates. From the perspective of reducing manufacturing costs and ensuring a safe manufacturing environment, it is preferable to use a water-soluble compound of sodium that can be used in aqueous solution during the loading operation. In particular, using sodium nitrate or sodium acetate as the sodium is preferable because it readily converts to iron oxide during calcination, and the subsequent reduction treatment of sodium oxide is also easy. 【0034】 Catalyst A is obtained through the above process. The catalyst A obtained through the above process is an oxide-based compound, but it may be subjected to a reduction treatment as a post-treatment. By increasing the temperature or duration of the reduction process, the reduction conditions become more stringent. This increases the proportion of metal compounds in catalyst A that are reduced from oxide to metallic after the reduction process. With extremely stringent reduction treatment, it is even possible to reduce the catalyst to a state consisting solely of active metals. However, under typical reduction conditions, catalyst A often ends up in a chemical state containing some iron oxide, cobalt oxide, aluminum oxide, and sodium oxide. 【0035】 Catalyst A, after the reduction treatment, should be handled in a way that prevents it from being exposed to air and subsequently oxidized and deactivated. A stabilization treatment that isolates the iron metal surface of the catalyst from the atmosphere is preferable, as it allows for handling of catalyst A in the atmosphere. Stabilization treatments include passivation, which involves exposing the catalyst to nitrogen, carbon dioxide, or an inert gas containing low concentrations of oxygen to oxidize only the outermost layer of the active metal on the catalyst surface; and, in the case of reactions producing hydrocarbons using carbon dioxide and hydrogen as raw materials, which are carried out in the liquid phase, treatments such as immersion in a reaction solvent or molten wax to isolate the catalyst from the atmosphere. However, the appropriate stabilization treatment should be performed depending on the situation. 【0036】 (Second catalyst layer) The second catalyst layer contains zeolite. The second catalyst layer may also contain other components besides zeolite. However, the proportion of zeolite in the second catalyst layer should be, for example, 80% by mass or more (preferably 90% by mass or more, more preferably 95% by mass or more). 【0037】 Zeolites with a molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) of 150 or less are applicable. By using a zeolite with a molar ratio (SiO2 / Al2O3) of 150 or less, the olefin produced by catalyst A is converted to paraffin, increasing the paraffin selectivity of the product. As a result, LPG productivity is improved. In zeolites, the molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) is: A value of 30 or less is preferable, and 25 or less is more preferable. However, in zeolites, the molar ratio of SiO2 to Al2O3 (SiO2 / Al2O3) is preferably 1.0 or higher, and more preferably 10.0 or higher, from the viewpoint of reactivity in olefin conversion. 【0038】 Both natural and synthetic zeolites can be used. From the perspective of improving LPG productivity, it is preferable to use H-ZSM-5 zeolite, which is obtained by ion-exchanging ZSM-5 type zeolite with protons. Here, H-ZSM-5 zeolite refers to a proton-exchange aluminosilicate zeolite whose skeletal structure code is ZSM-5 (Zeolite Socony Mobil-5). Aluminosilicate zeolite with a skeleton structure code of type ZSM-5 (Zeolite Socony Mobil-5) that has not undergone proton exchange is called "ZSM-5 zeolite". 【0039】 The mass ratio of zeolite to catalyst A is preferably 0.1 to 3.5. That is When the mass ratio of zeolite is 0.1 or higher, the olefin produced by catalyst A is effectively converted to paraffin by the acid sites of the zeolite, resulting in sufficient LPG productivity. A higher mass ratio of zeolite facilitates the efficient conversion of olefins produced by catalyst A into paraffin. However, increasing the amount of zeolite increases catalyst costs. Furthermore, the larger the catalytic reactor, the higher the equipment costs. Therefore, a zeolite mass ratio of 3.0 or less is preferable. Therefore, when the mass ratio of zeolite is within the above range, the olefin produced by catalyst A is more easily converted to paraffin, and the productivity of saturated hydrocarbons with 3 to 4 carbon atoms is more easily improved. The lower limit of the zeolite mass ratio is preferably 0.3 or higher, 0.5 or higher, or more preferably 1.0 or higher. The upper limit of the zeolite mass ratio is preferably 3.0 or less, 2.5 or less, or more preferably 2.0 or less. In particular, the mass ratio of zeolite is preferably 0.3 to 3.5, and more preferably 0.5 to 3.0. 【0040】 (Other components of the first and second catalyst layers) Other components that may be included in the first and second catalyst layers include silica, alumina, and zirconia. These other components can be included in each layer for purposes such as moderating the exothermic or endothermic reaction during catalytic reactions and facilitating thermal control. 【0041】 (Method of manufacturing a catalyst) One example of a method for producing the catalyst of the present invention is to press-molde a powder for forming a first catalyst layer containing powdered catalyst A and a powder for forming a second catalyst layer containing powdered zeolite, and then stack the second catalyst layer on the downstream side and the first catalyst layer on the upstream side in a single reactor. Other methods for producing the catalyst of the present invention include using an extruded catalyst to fill the upstream reactor A with a first catalyst layer and the downstream reactor B with a second catalyst layer, thereby filling the entire reactor with a stacked structure. 【0042】 (Method of manufacturing hydrocarbons) Next, a method for producing hydrocarbons by reacting carbon dioxide and hydrogen using the catalyst of the present invention will be described. The present invention provides a method for producing hydrocarbons by contacting a mixed gas containing carbon dioxide and hydrogen with a hydrocarbon production catalyst. However, in the hydrocarbon production method of the present invention, the catalysts of the present invention are arranged such that the first catalyst layer is located upstream and the second catalyst layer is located downstream in the flow direction of the mixed gas. In other words, in the hydrocarbon production method of the present invention, hydrocarbons are produced by generating olefins with catalyst A in the first catalyst layer and converting the generated olefins into paraffins with zeolite in the second catalyst layer. 【0043】 While there are no particular restrictions on the reaction conditions, good results are generally obtained when the reaction temperature is 250-400°C and the reaction pressure is 1.0-6.0 MPa. 【0044】 When the reaction temperature is 250°C or higher, sufficient catalytic activity is more likely to be exhibited. When the reaction temperature is below 400°C, the selectivity of by-products such as methane increases, the decrease in catalyst life is suppressed, and LPG productivity tends to improve. Therefore, the reaction temperature is preferably set in the range of 250 to 400°C, and more preferably in the range of 280 to 330°C. 【0045】 The reaction pressure is preferably 1.0 to 6.0 MPa. When the reaction pressure is 1.0 MPa or higher, sufficient catalytic activity is more likely to be exhibited. If the reaction pressure is 6.0 MPa or less, it becomes possible to avoid setting a high pressure resistance design for the plant, which helps to reduce equipment costs. Therefore, it is preferable to set the reaction pressure within the above range. 【0046】 When the reaction temperature or pressure is low, the catalytic reaction proceeds slowly, resulting in a tendency for a low carbon dioxide conversion rate. Because the hydrocarbon chain growth proceeds slowly, short-chain hydrocarbons are more easily produced, and the selectivity for hydrocarbons with 3 to 4 carbon atoms tends to be high. Higher reaction temperatures or pressures tend to result in more vigorous catalytic reactions and thus a higher carbon dioxide conversion rate. Rapid hydrocarbon chain growth also facilitates the formation of long-chain hydrocarbons, while the selectivity for hydrocarbons with 3-4 carbon atoms tends to be lower. Furthermore, high reaction temperatures promote hydrocarbon decomposition, leading to the formation of by-products such as methane. 【0047】 Therefore, there is a trade-off between the carbon dioxide conversion rate and the selectivity of hydrocarbons with 3 to 4 carbon atoms. By controlling the reaction temperature or pressure within a certain range, hydrocarbons with 3 to 4 carbon atoms, and ultimately LPG, can be obtained with high productivity. 【0048】 The reaction mode can be selected from fixed bed, slurry bed, moving bed, etc., depending on the reaction conditions, and is not particularly limited. However, from the viewpoint of catalytic activity, a reaction temperature exceeding 250°C is preferable, and a fixed bed is preferable. In a slurry bed, it is preferable that a solvent that becomes liquid under the reaction conditions is produced by the reaction, but at reaction temperatures exceeding 250°C, most hydrocarbons are gaseous, making it difficult to maintain the reaction in a slurry bed. Therefore, it is preferable to use a fixed bed as the reaction method and react carbon dioxide and hydrogen under a catalyst to produce hydrocarbons. 【0049】 When a fixed bed reactor is used, it is preferable to mold the catalyst into a pellet shape, taking into account the pressure loss within the reactor. 【0050】 In the case of relatively small-scale plants that have a hydrocarbon conversion plant attached to a carbon dioxide emission source, microchannel reactors may be advantageous. However, considering that the catalyst is packed into a channel on the order of millimeters or less, a catalyst particle size of about 20 to 250 μm is preferable. 【0051】 In the hydrocarbon production method of the present invention, the mixed gas of carbon dioxide and hydrogen used as the reaction gas (i.e., raw material gas) is preferably a gas in which the total amount of carbon dioxide and hydrogen is 50% or more by volume, from the viewpoint of productivity, and in particular, the molar ratio of hydrogen to carbon dioxide (hydrogen / carbon dioxide) is preferably in the range of 0.5 to 4.0. This is because when the molar ratio of hydrogen to carbon dioxide is 0.5 or higher, the amount of hydrogen present in the raw material gas is sufficient, so the hydrogenation reaction of carbon dioxide proceeds easily and productivity is high. On the other hand, when the molar ratio of hydrogen to carbon dioxide is 4.0 or lower, the amount of carbon dioxide present in the raw material gas is sufficient, so in combination with the high activity of the catalyst of the present invention, hydrocarbon productivity is high. [Examples] 【0052】 The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Since the carbon dioxide conversion rate in this reaction increases with increasing reaction temperature and pressure, catalyst performance must be compared at the same reaction temperature and pressure. 【0053】 (Preparation of the catalyst for the first catalyst layer) An oxide containing iron, cobalt, and aluminum was synthesized using a coprecipitation method, and then sodium was supported on the oxide by an impregnation method to obtain a catalyst. Specifically, the procedure is as follows. Iron nitrate hydrate, cobalt nitrate hydrate, and aluminum nitrate hydrate were dissolved in aqueous solutions as raw materials (precursors), and a sodium carbonate aqueous solution was added as a precipitating agent to precipitate the complex hydroxide. After that, with the complex oxide settled, it was aged at 80°C for 4 hours, dried at 120°C for 12 hours, and calcined at 400°C for 4 hours to obtain the iron-cobalt-aluminum complex oxide. Subsequently, the composite oxide was impregnated with a solution containing sodium nitrate, dried at 120°C for 12 hours, and calcined at 400°C for 4 hours to obtain a catalyst. However, the amounts of iron nitrate hydrate, cobalt nitrate hydrate, aluminum nitrate hydrate, and sodium nitrate were adjusted so that the molar percentages of cobalt, aluminum, and sodium relative to iron in the resulting catalyst were as shown in Table 1. 【0054】 (Preparation of the catalyst for the second catalyst layer) As catalysts for the second catalyst layer, SAPO-11 phosphate-based zeolite, NaY-type zeolite, and H-ZSM-5 zeolite (SiO2 / Al2O3 = 24, 105, or 1100) were prepared. 【0055】 (Comparative Example 1) The catalyst in the second catalyst layer was not used, and the catalyst in the first layer with the composition shown in Table 1 was used as the catalyst for Comparative Example 1. 【0056】 (Comparative Examples 2-4, Examples 1-7) According to Table 1, the catalysts for each example were obtained by layering the catalysts for the first and second catalyst layers. Specifically, the catalysts for the first and second catalyst layers were compressed and molded to a particle size of 300-500 μm, and the catalysts for each example were obtained by layering the second catalyst layer downstream of the reactor and the first catalyst layer upstream. However, the mass ratio of the catalyst in the second catalyst layer to the catalyst in the first catalyst layer (i.e., the mass ratio of the zeolite to catalyst A) was adjusted to the values ​​shown in Table 1. 【0057】 (characteristic) [CO2 conversion rate, CO selectivity, selectivity for each hydrocarbon, olefin / paraffin ratio of C3-C4 hydrocarbons, LPG yield] The reactivity of the catalysts in each example was evaluated as follows. The catalysts for each example were packed into tubular reactors. After packing the reactors with catalysts, a reduction treatment was performed, and under the reaction conditions shown in Table 1, the reaction gas flow rate (H2 / CO2=3.0) was adjusted so that W (catalyst mass) / F (synthesis gas flow rate); (g·h / mol) = 5.0, and the FT synthesis process was carried out. 【0058】 The composition of the supply and outlet gases was then determined by gas chromatography, and the following reaction characteristics were calculated. CO2 conversion rate • CO selection rate • Selectivity for hydrocarbons with one carbon atom (methane) (referred to as "C1 selectivity") • Selectivity of hydrocarbons with 2 carbon atoms (denoted as "C2 selectivity") • Selectivity of hydrocarbons with 3-4 carbon atoms ("C 3-4 (Represented as "selection rate") • Selectivity of hydrocarbons with 5 or more carbon atoms ("C 5+ (Represented as "selection rate") • Olefin / paraffin ratio of hydrocarbons with 3-4 carbon atoms ("C 3-4 (Written as "O / P") • Paraffin yield of hydrocarbons with 3-4 carbon atoms (indicated as "LPG yield") 【0059】 The CO2 conversion rate, selectivity, olefin / paraffin ratio, and LPG yield were calculated based on the following formula. In the formula, C 3-4 The selectivity (%) of paraffin indicates the olefin / paraffin ratio. 【number】 【0060】 [Table 1] 【0061】 From the above results, it can be seen that the catalyst of this example is a highly active hydrocarbon production catalyst that can increase the productivity of LPG composed of propane and butane compared to the catalyst of the comparative example.

Claims

[Claim 1] A first catalyst layer containing catalyst A, which contains iron, cobalt, aluminum, and sodium, The first catalyst layer is laminated with Al ２ O ３ SiO ２ Molar ratio (SiO ２ / Al ２ O ３ A second catalyst layer containing a zeolite in which the ratio is 150 or less, A hydrocarbon production catalyst. [Claim 2] In the zeolite, Al ２ O ３ The molar ratio of SiO ２ to (SiO ２ / Al ２ O ３ ) is 50 or less, and the hydrocarbon production catalyst according to claim 1. [Claim 3] The hydrocarbon production catalyst according to claim 1, wherein the mass ratio of the zeolite to the catalyst A is 0.5 to 3.

0. [Claim 4] The hydrocarbon production catalyst according to claim 1, wherein the zeolite is H-ZSM-5 zeolite. [Claim 5] A method for producing hydrocarbons using a hydrocarbon production catalyst according to any one of claims 1 to 4, A method for producing hydrocarbons, comprising contacting a mixed gas containing carbon dioxide and hydrogen with the hydrocarbon production catalyst to produce hydrocarbons.

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