Hydrocarbon production catalyst, method for producing a hydrocarbon production catalyst, and method for producing hydrocarbons

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 dioxide and hydrogen as raw materials, a method for producing the hydrocarbon production catalyst, and a method for producing hydrocarbons using the hydrocarbon production catalyst. [Solution] A hydrocarbon production catalyst comprising cerium oxide and catalyst component A supported on the cerium oxide, wherein catalyst component A comprises iron, at least one co-catalyst X selected from the group consisting of cobalt, aluminum and zinc, and sodium; a method for producing the hydrocarbon production catalyst; and a method for producing hydrocarbons using the hydrocarbon production catalyst.

Description

Technical Field

[0001] The present invention relates to a hydrocarbon production catalyst, a method for producing a hydrocarbon production catalyst, and a method for producing a hydrocarbon.

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) composed 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 carried out.

[0004] For example, Patent Document 1 discloses "a hydrocarbon production catalyst comprising a compound having, as a metal component, iron, sodium, and at least one selected from the group consisting of zinc, manganese, and copper."

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0006] In the production of hydrocarbons using carbon dioxide and hydrogen as raw materials, including Patent Document 1, it is common to use a catalyst mainly composed of iron because of 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. 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.

[0007] 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, a method for producing the hydrocarbon production catalyst, and a method for producing hydrocarbons using the hydrocarbon production catalyst. [Means for solving the problem]

[0008] The means for solving the problem include the following aspects: <1> It comprises cerium oxide and catalyst component A supported on the cerium oxide, The catalyst component A is Iron and, A co-catalyst X selected from the group consisting of cobalt, aluminum, and zinc, Sodium and, A hydrocarbon manufacturing catalyst containing [specific component]. <2> The catalyst component A includes at least the cobalt as the co-catalyst X. <1> A hydrocarbon manufacturing catalyst as described above. <3> The catalyst component A includes, as the co-catalyst X, at least the cobalt and the aluminum. <1> or <2> A hydrocarbon manufacturing catalyst as described above. <4> The mass ratio of cerium oxide to the total hydrocarbon production catalyst is 20 to 60% by mass. <1> ~ <4> A hydrocarbon production catalyst as described in any one of the items. <5> <1> ~ <4> A method for producing a hydrocarbon catalyst as described in any one of the items, A first step involves supporting the iron and the co-catalyst X on the cerium oxide by a precipitation method, A second step involves supporting sodium on the cerium oxide on which the iron and the co-catalyst X are supported by an impregnation method, A method for producing a hydrocarbon catalyst having <6> <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]

[0009] 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, a method for producing the hydrocarbon production catalyst, and a method for producing hydrocarbons using the hydrocarbon production catalyst. [Modes for carrying out the invention]

[0010] 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. The amount of each component in a composition refers to the total amount of any multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component are present in the composition. The term "process" includes not only independent processes, but also any process that cannot be clearly distinguished from other processes, as long as its intended purpose is achieved. "Combination of preferred embodiments" is a more preferred embodiment.

[0011] Also, "room temperature" indicates a temperature within the range of 23°C ± 3°C. Also, the "hydrocarbon production catalyst" is also simply referred to as the "catalyst".

[0012] <Hydrocarbon production catalyst> The hydrocarbon production catalyst of the present invention has cerium oxide and a catalyst component A supported on the cerium oxide. The catalyst component A contains iron, at least one promoter X selected from the group consisting of cobalt, aluminum, and zinc, and sodium.

[0013] Due to the above configuration, 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.

[0014] By including, in addition to iron, at least one promoter X (selected from the group consisting of cobalt, aluminum, and zinc) and sodium as promoters in the catalyst component A, the chain growth of hydrocarbons is promoted, and the yield of hydrocarbons having 3 to 4 carbon atoms increases. In particular, cobalt as the promoter X promotes the reaction by acting as an active site in addition to the active sites of iron, and the hydrocarbons produced by cobalt with high hydrogenation ability shift to the short-chain side. Also, aluminum and zinc as the promoter X promote the reaction of the raw materials by improving the dispersibility of iron, which is an active site. Therefore, by including at least one selected from the group consisting of cobalt, aluminum, and zinc in the catalyst component A, the yield of hydrocarbons having 3 to 4 carbon atoms (that is, the yield of LPG) increases. In addition, when the promoter X and sodium coexist as promoters, the formation of iron carbide, which is an active species of the FT synthesis reaction, is promoted in an atmosphere of carbon dioxide and hydrogen, the conversion rate of carbon dioxide is improved, and as a result, the yield of hydrocarbons having 3 to 4 carbon atoms increases. On the other hand, the cerium oxide supporting catalyst component A increases the local hydrogen concentration in the reaction field, converting the olefin produced by catalyst component A into paraffin. This increases the paraffin selectivity of the resulting hydrocarbon.

[0015] 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. Furthermore, the catalyst of the present invention makes it possible to produce LPG with high efficiency in a single-step reaction in hydrocarbon production using carbon dioxide and hydrogen as raw materials.

[0016] The details of the catalyst of the present invention will be described below.

[0017] The catalyst of the present invention is a catalyst in which catalyst component A is supported on cerium oxide. The catalyst of the present invention may contain small amounts of impurities in addition to cerium oxide and catalyst component A.

[0018] Here, the number of moles or mass of catalyst component A (iron, co-catalyst X, and sodium) and impurities are measured by ICP-AES after pretreatment of the catalyst such as acid decomposition or alkali melting. Furthermore, the cerium oxide content (mass ratio) is determined by the cerium oxide peak measured by XRD (X-ray diffraction). Specifically, the measurement is performed as follows: The XRD measurement results are subjected to Rietveld analysis to analyze the proportion of each crystalline phase, and the content is determined by the proportion of the cerium oxide crystalline phase in the whole. In addition, in the catalyst of this invention, it is sufficient to include only trace amounts of cerium oxide. The cerium oxide content relative to the total catalyst is preferably 10.0 to 90.0% by mass, and more preferably 20.0 to 60.0% by mass.

[0019] (Catalyst component A) Catalyst component A contains iron, co-catalyst X, and sodium. The co-catalyst X is selected from the group consisting of cobalt, aluminum, and zinc. From the viewpoint of improving LPG productivity, the co-catalyst X is preferably cobalt, and more preferably cobalt and aluminum. Specifically, catalyst component A preferably contains at least cobalt as co-catalyst X, and more preferably contains at least cobalt and aluminum as co-catalyst X. In particular, when cobalt and aluminum coexist as co-catalyst X, the cobalt, which acts as an active site and has high hydrogenation ability, is dispersed by the aluminum (i.e., the active site is dispersed by the cobalt). As a result, the conversion rate of carbon dioxide improves, and the yield of hydrocarbons with 3 to 4 carbon atoms tends to increase.

[0020] The content of catalyst component A will be explained below.

[0021] The iron content of catalyst component A relative to the total components is preferably 5.0% by mass or more and 90.0% by mass or less, and more preferably 25.0% by mass or more and 75.0% by mass or less. When the iron content is within the above range, it fully exhibits its function as an active species, making it easier to improve the carbon dioxide conversion rate and the productivity of hydrocarbons with 3 to 4 carbon atoms. As a result, the productivity of LPG is more easily improved.

[0022] 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. As a result, the productivity of LPG tends 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.

[0023] 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. As a result, the productivity of LPG tends to improve. The lower limit for the molar percentage of aluminum relative to iron is 1.0% or higher, with 2.0% or higher being more preferable. The upper limit for the molar percentage of aluminum relative to iron is 15.0% or less, with 12.0% or less being more preferable.

[0024] The molar percentage of zinc relative to iron is preferably 0.1 to 120.0%. When the molar percentage of zinc is 0.1% or higher, the zinc 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 zinc is 120.0% or less, the relative decrease in the content of iron, which is an active species, is suppressed. Therefore, when the molar percentage of zinc 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. As a result, the productivity of LPG tends to improve. The lower limit of the molar percentage of zinc relative to iron is preferably 5.0% or more, or more preferably 10.0% or more. The upper limit of the molar percentage of zinc relative to iron is more preferably 55.0% or less, 50.0% or less, 20% or less, or 15% or less.

[0025] 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. As a result, the productivity of LPG tends 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%.

[0026] Here, iron, co-catalyst X (at least one of cobalt, aluminum, and zinc), and sodium are considered to exist in the form of oxides within the catalyst. The number of moles of each component is calculated based on the total number of all chemical forms of each metal component.

[0027] Iron, co-catalyst X (at least one of cobalt, aluminum, and zinc), 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.

[0028] Iron, co-catalyst X (at least one of cobalt, aluminum, and zinc), and sodium do not need to exist solely in a metallic state, as they are reduced to metallization during the reaction by the reducing atmosphere and perform the necessary catalytic functions, even if they exist as oxides. Note that trace amounts of raw materials (precursors) may remain in the catalyst.

[0029] (Cerium oxide) Cerium oxide is an oxide that functions as a catalyst support for Fe-based catalysts. Cerium oxide only needs to be included in trace amounts in the catalyst. It is presumed that the inclusion of a cerium oxide support in the catalyst increases the local hydrogen concentration on the catalyst surface, which promotes the conversion of olefins produced by catalyst component A to paraffins, thereby improving LPG productivity.

[0030] However, from the viewpoint of achieving sufficient improvements in LPG productivity, the mass ratio of cerium oxide to the total catalyst is preferably 20 to 60% by mass. When the mass ratio of cerium oxide is 20% by mass or more, the conversion from olefin to paraffin produced by catalyst component A is sufficiently promoted. When the mass ratio of cerium oxide is 60% by mass or less, the amount of catalyst component A that generates the olefin for conversion to paraffin is ensured. Therefore, when the mass ratio of cerium oxide is within the above range, LPG productivity tends to improve. The lower limit of the mass ratio of cerium oxide is more preferably 30% by mass or more. The upper limit of the mass ratio of cerium oxide is more preferably 50% by mass or less.

[0031] (Method of manufacturing a catalyst) The method for producing the catalyst of the present invention is not particularly limited, but examples of methods for producing the catalyst include hydrothermal synthesis, coprecipitation, homogeneous precipitation, sol-gel method, and flux method. Among these, the method for producing the catalyst of the present invention is preferably a method using precipitation.

[0032] Specifically, the method for producing the catalyst of the present invention is, for example, The first step involves supporting iron and co-catalyst X on cerium oxide by precipitation, The second step involves supporting sodium on cerium oxide (hereinafter also referred to as catalyst support) on which iron and co-catalyst X are supported by an impregnation method, It has. This catalyst manufacturing method yields a highly active hydrocarbon production catalyst that can significantly increase the productivity of LPG (Large Propane and Butane) in hydrocarbon production using carbon dioxide and hydrogen as raw materials.

[0033] -First step- In the first step, iron and co-catalyst X (at least one selected from the group consisting of cobalt, aluminum, and zinc) are supported on cerium oxide. Specifically, in the first step, a base is brought into contact with cerium oxide as a support and a mixture of raw materials (precursors) containing an iron compound and a co-catalyst X (at least one of a cobalt compound, an aluminum compound, or a zinc compound) to obtain a precipitate. The obtained precipitate is washed, dried, and calcined to obtain a metal oxide supported on cerium oxide.

[0034] Either homogeneous precipitation or coprecipitation method 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.

[0035] In the precipitation method, the iron compound used as the raw material (precursor) and the compound containing co-catalyst X (at least one of a cobalt compound, an aluminum compound, or a zinc compound) 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, the iron compound and the compound containing co-catalyst X (at least one of the cobalt compound, aluminum compound, and zinc compound) can be used in the form of nitrates, carbonates, acetates, chlorides, acetylacetonates, etc. The iron compound, zinc compound, cobalt compound, and aluminum compound may also be used in the form of hydrated nitrates, carbonates, acetates, or chlorides. From the viewpoint of reducing manufacturing costs and ensuring a safe manufacturing environment, it is preferable that the iron compound and the compound containing co-catalyst X (at least one of the cobalt compound, aluminum compound, and zinc compound) each be water-soluble compounds that can be used in aqueous solution during the precipitation operation. In particular, using an iron nitrate or iron acetate as the compound containing the iron compound and co-catalyst X (at least one of a cobalt compound, an aluminum compound, or a zinc compound) is preferable because it readily changes to iron oxide during calcination, and the subsequent reduction treatment of iron oxide, zinc oxide, cobalt oxide, and aluminum oxide is also easy.

[0036] -Second step- In the second step, sodium is supported on the catalyst support (cerium oxide on which iron and co-catalyst X are supported) 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).

[0037] Here, the method for supporting sodium on the catalyst support 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 support (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).

[0038] 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 changes to iron oxide during calcination, and the subsequent reduction treatment of sodium oxide is also easy.

[0039] The catalyst of the present invention is obtained through the above steps. The catalyst obtained through the above steps is an oxide-based compound, but a reduction treatment may be performed 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 the catalyst 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, the catalyst of the present invention often exists in a chemical state that partially contains iron oxide, an oxide of co-catalyst X (cobalt oxide, and at least one of aluminum oxide and zinc oxide), and sodium oxide.

[0040] After the reduction treatment, the catalyst should be handled in a way that prevents oxidation and deactivation by exposure to the atmosphere. Stabilization treatment that isolates the iron metal surface of the catalyst from the atmosphere is preferable, as it allows for handling of the catalyst 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.

[0041] (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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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]

[0051] 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.

[0052] (Comparative Examples 1-3) An oxide containing iron and a co-catalyst X (at least one of cobalt, aluminum, and zinc) was synthesized by coprecipitation. Subsequently, sodium was supported on the oxide by impregnation to obtain the catalyst. Cerium oxide was not used. The details are as follows: As raw materials (precursors), suitable samples from iron nitrate hydrate, zinc nitrate hydrate, cobalt nitrate hydrate, and aluminum nitrate hydrate were dissolved in an aqueous solution, 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 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, zinc nitrate hydrate, cobalt nitrate hydrate, aluminum nitrate hydrate, and sodium nitrate were adjusted so that the molar percentages of zinc, cobalt, aluminum, and sodium relative to iron in the resulting catalyst were as shown in Table 1.

[0053] (Examples 1-5) The catalyst was obtained by supporting iron and co-catalyst X (at least one of cobalt, aluminum, and zinc) on cerium oxide using a coprecipitation method, and then supporting sodium on the oxide using an impregnation method. Specifically, the process is as follows. As raw materials (precursors), suitable samples from iron nitrate hydrate, cobalt nitrate hydrate, aluminum nitrate hydrate, and zinc nitrate hydrate were dissolved in an aqueous solution, and then cerium oxide was added and stirred. 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 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 cerium oxide, iron nitrate hydrate, cobalt nitrate hydrate, aluminum nitrate hydrate, zinc nitrate hydrate, and sodium nitrate were adjusted so that the molar percentages of zinc, cobalt, aluminum, and sodium relative to iron in the resulting catalyst, and the mass percentage of cerium oxide in the total catalyst, were as shown in Table 1.

[0054] (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.

[0055] 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 "OP / P") • Paraffin yield of hydrocarbons with 3-4 carbon atoms (indicated as "LPG yield")

[0056] 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.

[0057]

number

[0058] [Table 1]

[0059] 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

1. It comprises cerium oxide and catalyst component A supported on the cerium oxide, The catalyst component A is Iron and, A co-catalyst X selected from the group consisting of cobalt, aluminum, and zinc, Sodium and, A hydrocarbon manufacturing catalyst containing [specific component].

2. The hydrocarbon production catalyst according to claim 1, wherein the catalyst component A includes at least the cobalt as the co-catalyst X.

3. The hydrocarbon production catalyst according to claim 1, wherein the catalyst component A includes at least the cobalt and aluminum as the co-catalyst X.

4. The hydrocarbon production catalyst according to claim 1, wherein the mass ratio of cerium oxide to the entire hydrocarbon production catalyst is 20 to 60% by mass.

5. A method for producing a hydrocarbon catalyst according to any one of claims 1 to 4, A first step involves supporting the iron and the co-catalyst X on the cerium oxide by a precipitation method, A second step involves supporting sodium on the cerium oxide on which the iron and the co-catalyst X are supported by an impregnation method, A method for producing a hydrocarbon catalyst having

6. 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.

Images