Catalyst systems for Fischer-Tropsch reactions

Abstract

To provide a new technique that makes it possible to produce liquid hydrocarbons from raw material gas containing at least one of carbon dioxide or carbon monoxide and hydrogen.SOLUTION: A catalyst according to one embodiment of the present invention contains a carrier primarily composed of ferric oxide, and an alkali metal supported on the carrier. The carrier has a specific surface area of 20 m2 / g or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to catalyst technology used in producing hydrocarbons. [Background technology]

[0002] As a method for effectively utilizing carbon dioxide contained in exhaust gases, etc., it is known to produce liquid hydrocarbons with high energy density from carbon dioxide and hydrogen in the presence of a catalyst (see Patent Document 1).In addition, as a method for producing hydrocarbons using hydrogen and carbon monoxide, the Fischer-Tropsch process (hereinafter referred to as the "FT process") is known (see Non-Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-80309 [Non-patent literature]

[0004] [Non-Patent Document 1] Energy & Fuels, Vol. 23, 4195(2009) Summary of the Invention [Problem to be solved by the invention]

[0005] The cobalt-based catalysts typically used in the FT reaction selectively produce methane from carbon dioxide, so when a feedstock containing carbon dioxide is used, a large amount of methane is produced, making it impossible to obtain liquid hydrocarbons in high yields.

[0006] The present invention has been made in view of the above circumstances, and one of its exemplary objects is to provide a new catalyst capable of producing liquid hydrocarbons from a feed gas containing at least one of carbon dioxide and carbon monoxide and hydrogen. [Means for solving the problem]

[0007] In order to solve the above problems, a catalyst according to one embodiment of the present invention comprises a carrier containing ferric oxide as a main component and an alkali metal supported on the carrier. 2 / g or more. [Effects of the Invention]

[0008] According to one aspect of the present invention, a new catalyst capable of producing liquid hydrocarbons from a feed gas containing at least one of carbon dioxide and carbon monoxide and hydrogen is provided. Liquid hydrocarbons can be obtained in high yield in the production of hydrocarbons. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the general configuration of a fixed-bed flow reactor according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] First, the embodiments of the present invention will be listed. A catalyst according to one embodiment of the present invention contains a carrier containing ferric oxide as a main component and an alkali metal supported on the carrier. The carrier has a specific surface area of ​​20 m 2 / g or more.

[0011] According to this embodiment, the yield of liquid hydrocarbons can be increased. Ferric oxide is also called iron(III) oxide or diiron trioxide.

[0012] The alkali metal may include at least one selected from the group consisting of sodium and potassium.

[0013] The carrier has a specific surface area of ​​40m 2 / g or more, and the pore volume is 0.15 cm 3 / g or more, which can further increase the yield of liquid hydrocarbons.

[0014] Another embodiment of the present invention is a catalyst system comprising: a reactor configured to introduce a feed gas through an upstream inlet and discharge hydrocarbons produced from the feed gas through a downstream outlet; a first catalyst for causing a reverse shift reaction, which is disposed on the inlet side of the reactor; and a second catalyst, which contains the aforementioned ferric oxide-based support, and is disposed on the outlet side of the reactor.

[0015] According to this embodiment, hydrocarbons can be easily produced from carbon dioxide and hydrogen contained in the feed gas introduced into the inlet side of the reactor, without removing carbon monoxide produced in the reverse shift reaction from the reactor.

[0016] The first catalyst may contain copper and zinc oxide. This allows efficient production of carbon monoxide from carbon dioxide contained in the raw material gas. The first catalyst can also be used as a heat absorption part of the second catalyst.

[0017] The first catalyst may contain rhodium.

[0018] The first catalyst may contain platinum.

[0019] The first catalyst may contain iron-chromium.

[0020] A temperature adjustment mechanism may be further provided between the first catalyst and the second catalyst to adjust the temperature of at least one of the first catalyst and the second catalyst, thereby allowing the second catalyst to be used at a relatively low temperature even if it generates heat due to a catalytic reaction.

[0021] Another aspect of the present invention is a method for producing a catalyst. This method includes the steps of: mixing an aqueous solution of iron nitrate with a basic aqueous solution; filtering a precipitate containing iron(III) hydroxide produced in the mixing step; washing the filtered iron(III) hydroxide; calcining the washed iron(III) hydroxide to produce ferric oxide; and supporting an alkali metal on the ferric oxide as a carrier. The carrier is a ferric oxide having a specific surface area of ​​20 m. 2 / g or more.

[0022] When an aqueous solution containing ammonia is used in the mixing step, the iron(III) hydroxide precipitate produced in the mixing step does not contain alkali metals, as compared to when sodium hydroxide or potassium hydroxide is used. If the precipitate contains alkali metals, it is necessary to remove as much of the contained alkali metal as possible to improve the accuracy of the amount of alkali metal supported in the subsequent support step, which increases production costs. In contrast, according to this embodiment, by using an aqueous solution containing ammonia instead of an alkaline aqueous solution, it is possible to reduce the effort required for cleaning during filtration and the effort required to determine the content of residual alkali metals.

[0023] When a basic aqueous solution containing the same alkali metal as the alkali metal to be supported in the mixing step is used, the amount of alkali remaining in the washing step is measured, and the amount that is insufficient relative to the predetermined amount of alkali is supported, thereby making it possible to shorten the washing step and prevent an increase in production costs. In this case, the basic aqueous solution containing an alkali metal may be sodium hydroxide or potassium hydroxide.

[0024] Any combination of the above components and any transformation of the present invention into a method, device, system, etc. are also valid aspects of the present invention. Appropriate combinations of the above elements may also be included in the scope of the invention for which patent protection is sought by this patent application.

[0025] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. Identical or equivalent components, parts, and processes shown in the drawings are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in the drawings are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. The same components may have slightly different scales between the drawings. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, they do not represent any order or importance, but are used to distinguish one configuration from another.

[0026] (catalyst system) Next, the schematic configuration of a reactor including a catalyst system according to this embodiment will be described. Fig. 1 is a schematic diagram showing the schematic configuration of a fixed-bed flow reactor according to this embodiment. The reactor 10 shown in Fig. 1 includes, as a catalyst system, a reactor 12 configured to discharge hydrocarbons generated from a feed gas introduced through an upstream inlet 12a from a downstream outlet 12b, a first catalyst 14 arranged on the inlet 12a side of the reactor 12 and causing a reverse shift reaction, and a second catalyst 16 arranged on the outlet 12b side of the reactor 12, which is a catalyst containing a carrier mainly composed of ferric oxide, as described below.

[0027] In the first catalyst 14, carbon monoxide is produced from carbon dioxide by a reverse shift reaction. In the second catalyst 16, hydrocarbons are produced from carbon monoxide by a reaction according to the FT method. This catalyst system can easily produce gaseous or liquid hydrocarbons by introducing a raw material gas containing carbon dioxide and hydrogen into the inlet side of the reactor 12.

[0028] The reactor 10 produces CH4 and C2-C4 components, which are gaseous hydrocarbons with 1 to 4 carbon atoms, such as methane, ethane, propane, and butane, and C5+ components, which are hydrocarbons with 5 or more carbon atoms and are liquid oil components at normal pressure (for example, linear alkanes with a carbon number n of 5 or more), and performs gas-liquid separation of the gas components and oil components, and in some cases, fractional distillation to extract the desired components.

[0029] As described above, the catalyst system according to this embodiment includes at least two types of catalysts. The first catalyst 14 is a copper-based catalyst containing copper, and the second catalyst is an iron-based catalyst containing iron. The first catalyst 14 may contain copper and zinc oxide. This allows for efficient production of carbon monoxide from carbon dioxide contained in the feed gas. Furthermore, the reaction caused by the copper-based catalyst according to this embodiment is an endothermic reaction, and the first catalyst 14 can be used as a heat-absorbing portion of the second catalyst 16. A temperature adjustment mechanism may be provided between the first catalyst 14 and the second catalyst 16 to adjust the temperature of at least one of the first catalyst 14 and the second catalyst 16. The temperature adjustment mechanism may include a heat-absorbing medium itself, or may use a heat transfer medium cooled by another heat source in the plant. This allows the second catalyst to be used at a relatively low temperature even if it generates heat during the catalytic reaction.

[0030] The form of each catalyst body is not particularly limited, and may be, for example, a powder or a granular compact consisting of an aggregate of powder. The shape of the granular catalyst body is not particularly limited, and may be, for example, cylindrical, prismatic, spherical, or irregular. The particle size (maximum width) of the granular compact may be 1 mm or more and 50 mm or less. The particle size (maximum width) of the catalyst body powder may be 1 μm or more and less than 1000 μm.

[0031] The first catalyst 14 contains metallic copper, copper oxide (CuO), or both. While the copper-based catalyst body functions as a catalyst, it contains at least metallic copper. Therefore, the catalyst is subjected to a reduction treatment before being used in a reaction. Before the reduction treatment, the copper-based catalyst body often contains copper oxide.

[0032] The content of the copper component in the copper-based catalyst body is preferably 20 to 100 mass % based on the mass of the entire copper-based catalyst body when the amount of the copper component contained in the copper-based catalyst body is converted into the amount of metallic copper.

[0033] The copper-based catalyst body may further contain zinc oxide (ZnO). When the copper-based catalyst body contains zinc oxide, liquid hydrocarbons can be produced more efficiently. When the amount of copper element contained in the copper-based catalyst body is converted into the amount of copper oxide, the proportion of the amount of zinc oxide is preferably 10 to 70 mass %, and more preferably 20 to 50 mass %, based on the total amount of copper oxide and zinc oxide.

[0034] The first catalyst 14 may contain at least one metal or alloy selected from the group consisting of rhodium, platinum, or iron-chromium. By containing such a metal or alloy, carbon monoxide can be produced more efficiently from carbon dioxide contained in the raw material gas.

[0035] The copper-based catalyst body may further contain a carrier that supports a copper component. When the copper-based catalyst body contains zinc oxide, the zinc oxide is usually also supported on a carrier. The carrier is preferably alumina, such as γ-alumina. The content of the carrier in the copper-based catalyst body is, for example, 0.5 to 60 mass%, preferably 1 to 50 mass%, and more preferably 1 to 40 mass%, based on the total content of copper, zinc oxide, and alumina. The copper content here means the amount of copper component contained in the copper-based catalyst body converted into the amount of metallic copper.

[0036] A copper-based catalyst body containing a copper component and zinc oxide can be obtained, for example, by a method including a step of forming a precipitate containing copper and zinc by coprecipitation and a step of calcining the formed precipitate. The precipitate includes, for example, hydroxides, carbonates, or composite salts of copper and zinc. A copper-based catalyst body containing a copper component, zinc oxide, and a support can be obtained by forming a precipitate containing copper and zinc by coprecipitation from a solution containing a support (e.g., alumina).

[0037] The calcined body containing the copper component and zinc oxide formed by calcination may be powdered, and the powder may be further molded to form a granular compact. Examples of methods for molding the powder include extrusion molding and tablet molding. A molded body can also be obtained by molding a mixture containing the powder of the calcined body and carbon black.

[0038] The second catalyst 16 is an iron-based catalyst body, and contains a carrier whose main component is ferric oxide, and an alkali metal as an additive metal supported on the carrier.

[0039] The content of iron components in the iron-based catalyst body is preferably 5 to 100 mass % based on the mass of the entire iron-based catalyst body when the amount of iron components contained in the iron-based catalyst body is converted into the amount of iron oxide.

[0040] The added metal includes one or more types arbitrarily selected from alkali metals. For example, the added metal preferably includes at least one type selected from the group consisting of sodium, potassium, and cesium. Of course, two or more types of added metals may be used. When the added metal includes sodium, potassium, or cesium, liquid hydrocarbons can be produced more efficiently.

[0041] The content of the added metal in the iron-based catalyst body is preferably 0.2 to 40 mass%, and more preferably 0.5 to 20 mass%, based on the amount of the portion of the iron-based catalyst body other than the added metal. When the added metal includes sodium, the content of sodium in the iron-based catalyst body is preferably 0.2 to 20 mass%, and more preferably 0.5 to 10 mass%. When the added metal includes potassium, the total content of potassium and cesium in the iron-based catalyst body is preferably 0.2 to 40 mass%, and more preferably 0.5 to 20 mass%. When the added metal includes cesium, the content of cesium in the iron-based catalyst body is preferably 0.2 to 20 mass%, and more preferably 0.5 to 10 mass%. When the content of the added metal is within the above range, the conversion rate of carbon monoxide to hydrocarbons tends to be further improved.

[0042] The iron-based catalyst body is, for example, Fe 3+ The iron(III) oxide can be obtained by a method comprising the steps of: generating a precipitate of hydroxide containing trivalent iron from an aqueous solution containing the iron(III) oxide; calcining the precipitate to form a powder containing ferric oxide; mixing the powder with an aqueous solution containing the additive metal; and then drying the aqueous solution containing the additive metal.

[0043] The powder containing ferric oxide may be further molded to form a granular compact. Examples of methods for molding the powder include extrusion molding and tablet molding. A mixture containing the sintered powder and carbon black may also be molded to obtain a compact.

[0044] One method for producing hydrocarbons according to this embodiment involves producing hydrocarbons from a feed gas containing at least one of carbon dioxide or carbon monoxide and hydrogen in the presence of the above-described catalyst. A catalyst containing a combination of a copper-based catalyst and an iron-based catalyst can produce liquid hydrocarbons in a higher yield from a feed gas containing at least one of carbon dioxide or carbon monoxide and hydrogen, compared to, for example, a catalyst containing a composite oxide containing copper and iron and an alkali metal. The feed gas containing carbon dioxide and carbon monoxide may be, for example, a gas obtained by converting part of the carbon dioxide into carbon monoxide through an electrochemical reaction or an ordinary chemical reaction.

[0045] Each catalyst may be heated while the reaction for producing hydrocarbons from the raw material gas proceeds. The heating temperature for the reaction is, for example, 200 to 400° C. The raw material gas may contain only carbon dioxide or carbon monoxide, or may be a mixed gas containing carbon dioxide and carbon monoxide. [Example]

[0046] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples.

[0047] Example 1 1. Catalyst Preparation [Preparation of copper-based catalyst] 5.0 g of γ-alumina (Sumitomo Chemical Co., Ltd., BK-105) was suspended in 1.0 L of purified water by stirring with a homomixer. 300 mL of an aqueous solution containing 31.7 g of copper nitrate hydrate (Nacalai Reagent Co., Ltd.) and 38.1 g of zinc nitrate hydrate (Nacalai Reagent Co., Ltd.) was quickly added to the resulting suspension at room temperature, and the suspension was then stirred for an additional 1 hour. Subsequently, while continuing to stir with the homomixer, 300 mL of an aqueous solution containing 35.0 g of sodium carbonate (Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise at a rate of 5 mL / min using a roller pump at room temperature. The resulting suspension containing the precipitate was then allowed to stand at 35°C for 24 hours for aging. The supernatant was removed from the aged suspension by decanting, and the remaining precipitate was diluted again with water. This decanting and dilution process was repeated four times.

[0048] The precipitate was then removed by suction filtration, suspended again in pure water, and then removed by suction filtration. This procedure was repeated four times. The precipitate was thoroughly washed with water. The resulting precipitate was dried by heating at 120°C for 24 hours. The dried precipitate was calcined by heating under air flow in the following order: 150°C for 1 hour, 200°C for 1 hour, 250°C for 1 hour, 300°C for 1 hour, 350°C for 1 hour, and 400°C for 4 hours. Calcination yielded a black powder, which was a copper-based catalyst containing copper components and zinc oxide. This black powder was pulverized in a mortar and molded at a pressure of 40 MPa to obtain a cylindrical copper-based catalyst body with a diameter of 3 mm and a height of 3 mm.

[0049] [Preparation of iron-based catalyst] A solution with an iron ion concentration of 3 mol / L was prepared by dissolving 146.9 g of iron nitrate nonahydrate (Fujifilm Wako Pure Chemical Industries, Ltd.) in 120 ml of purified water with stirring at 70 °C. A sodium hydroxide solution (16.6 mol / L) prepared by dissolving 47.9 g of sodium hydroxide in 70 ml of purified water was added dropwise to the solution to adjust the pH to 11–12, producing a solution containing a precipitate of iron(III) hydroxide (Fe(OH)3). The precipitate contained in this solution was filtered using a vacuum pump, and the resulting filtrate was repeatedly washed until the alkali metal content was below a predetermined level. This is because if a large amount (unspecified amount) of alkali metal remained, it would be difficult to adjust the amount of alkali metal to be supported on the ferric oxide support in the subsequent alkali metal addition step.

[0050] The resulting precipitate was then dried by heating at 120°C for 12 to 20 hours. The dried precipitate was calcined by finally heating at 400°C for 5 hours while increasing the ambient temperature at a rate of 5°C / min under air flow. As a result, 28.7 g of ferric oxide (Fe2O3) was obtained.

[0051] Next, 5 g of the obtained ferric oxide was dissolved in an aqueous sodium hydroxide solution or an aqueous sodium nitrate solution, dried at 120°C for 12 to 20 hours, and finally calcined by heating at 400°C for 5 hours while increasing the ambient temperature at a rate of 5°C / min under air flow. This yields a powder of an iron-based catalyst body containing a support mainly composed of ferric oxide and an alkali metal supported on the support. Note that when ferric oxide is dissolved in an aqueous sodium hydroxide solution, the calcination step may be omitted and only the drying step may be performed. The powder is then molded to obtain a molded body of a predetermined shape. The iron-based catalyst body in each of the following examples is in the form of flakes with a diameter of 2 to 3 mm.

[0052] When potassium is to be supported on ferric oxide as the alkali metal, an aqueous solution of potassium hydroxide or potassium nitrate may be used, and when cesium is to be supported on ferric oxide as the alkali metal, an aqueous solution of cesium hydroxide or cesium nitrate may be used.

[0053] 2. Evaluation [Catalyst reduction treatment] A fixed-bed reactor tube with an inner diameter of 1.27 cm was sequentially filled with 0.5 g of copper-based catalyst and 3.5 g of iron-based catalyst (copper-based catalyst:iron-based catalyst = 1:7), and the copper-based catalyst and iron-based catalyst were arranged from the gas inlet side (upstream side) of the reactor tube. Subsequently, a flow gas consisting of 1% by volume hydrogen and nitrogen was circulated through the reactor tube at a flow rate of 200 Ncc / min under atmospheric pressure, while the catalyst temperature was raised from room temperature to 150°C over 1 hour. While maintaining the temperature at 150°C, the hydrogen concentration in the flow gas was sequentially changed to 2%, 10%, 20%, 50%, and 100% by volume. After changing to a flow gas (hydrogen gas) with a hydrogen concentration of 100% by volume, the flow state was maintained for 2 hours. Thereafter, while continuing to pass hydrogen gas, the temperature of the catalyst was raised to 350°C at a rate of 200°C / hour and maintained at 350°C for 7 hours, thereby reducing the catalyst.

[0054] [Reaction test] After the reduction treatment, the catalyst was cooled to 320°C while hydrogen gas was passed through at a flow rate of 200 Ncc / min. After the temperature was lowered, the pressure of the gas flow was increased to 0.8 MPa. After the pressure was increased, carbon dioxide was added at a flow rate of 67 Ncc / min, and the raw material gas consisting of hydrogen and carbon dioxide was passed through the reaction tube for 6 hours (gas space velocity: 4000 Ncc g-cat-1h). -1 ) The liquid that flowed out of the reaction tube over a period of 6 hours was collected. In addition, the gas that flowed out of the reaction tube was collected for 5 minutes just before the end of the test. The oil content of the supernatant of the liquid was analyzed using a gas chromatograph / flame ionization detector (GC-FID). The gas was analyzed using a gas chromatograph / thermal conductivity detector (GC-TCD) and a flame ionization detector (GC-FID). From the analysis results, the yield of the product relative to the amount of carbon dioxide in the feed gas was calculated.

[0055] Table 1 shows the specifications of carrier 1. Carrier 1 is a carrier made of 100% Fe2O3 (hematite) with a specific surface area of ​​56.7 m 2 / g, pore volume 0.239 cm 3 / g. Furthermore, Example 1 in Table 2 shows the proportions of each component in the hydrocarbon product produced when carbon dioxide and hydrogen were reacted as feed gases in a catalyst system (reactor 10) using an iron-based catalyst body in which sodium (4 wt%: based on the amount of the iron-based catalyst body other than the added metal; the same applies below) was supported on carrier 1. The proportions of each component were calculated for CH4, C2-C4, C5-C9, and C10+. In Tables 2 to 5, "CO2 conversion" indicates the conversion rate of carbon dioxide in the feed to carbon monoxide, and "CO conversion" indicates the conversion rate of carbon monoxide to hydrocarbons. As shown in Table 2, in Example 1, the yield of hydrocarbon products with a carbon number of 5 or more relative to the amount of carbon dioxide in the feed gas (hereinafter referred to as "C5+ yield") was 15.1%, which is an extremely good result. In addition, the selectivity of liquid hydrocarbons with a carbon number of 5 or more that can be used as oil (hereinafter referred to as "C5+ selectivity") was 55.1%, which is also an extremely good result.

[0056] [Table 1]

[0057] [Table 2]

[0058] (Comparative Example 1) As shown in Table 1, the carrier 2 in Comparative Example 1 is a carrier made of 100% Fe3O4 (Magnetite) and has a specific surface area of ​​85.9 m 2 / g, pore volume 0.361 cm 3 / g. Comparative Example 1 in Table 2 shows the proportions of each component in the hydrocarbon product produced when carbon dioxide and hydrogen were reacted as feed gases in a catalyst system (reactor 10) using an iron-based catalyst body with sodium (4 wt%) supported on carrier 2. As shown in Table 2, Comparative Example 1 has performance equivalent to or lower than that of Example 1. In other words, the catalyst system of Example 1 can achieve performance equivalent to or higher than that of Comparative Example 1, even though it uses carrier 1 (ferric oxide) which is different from carrier 2 used in the catalyst system of Comparative Example 1.

[0059] (Comparative Example 2) As shown in Table 1, the carrier 3 in Comparative Example 2 is a carrier made of 100% Fe3O4 (Magnetite), but has a specific surface area of ​​4.0 m 2 / g, pore volume 0.019 cm 3 / g, and both values ​​are smaller than those of the carrier 1 according to Example 1. Therefore, as shown in Table 2, in Comparative Example 2, the C5+ selectivity is less than 50%.

[0060] (Comparative Example 3) As shown in Table 1, the carrier 4 according to Comparative Example 3 was composed of 76% Fe2O3 (hematite) and 10% Fe 21.16 O 31.92 (Maghemite) is present at a ratio of 24%, and the specific surface area is 4.3m 2 / g, pore volume 0.020 cm 3 / g, and both values ​​are smaller than those of the carrier 1 according to Example 1. Therefore, as shown in Table 2, in Comparative Example 3, the C5+ selectivity is less than 50%.

[0061] Comparative Example 4 As shown in Table 1, the carrier 5 according to Comparative Example 4 contained 44% Fe2O3 (hematite) and 21.16 O 31.92 (Maghemite) is present at a ratio of 56%, and the specific surface area is 6.4m 2 / g, pore volume 0.035 cm 3 / g, both values ​​being smaller than those of Carrier 1 according to Example 1. Therefore, as shown in Table 2, in Comparative Example 4, the C5+ selectivity was about 40% and the C5+ yield was about 10%, which means that the performance was lower than that of the catalyst system according to Example 1.

[0062] As described above, from the results of Example 1 and Comparative Examples 1 to 4, the carrier containing ferric oxide as the main component according to the present embodiment has a specific surface area of ​​20 m 2 / g or more, and more preferably a specific surface area of ​​40m 2 The carrier according to the present embodiment preferably has a pore volume of 0.05 cm3 or more. 3 / g or more, more preferably a pore volume of 0.15 cm 3 / g or more, which can further increase the yield of liquid hydrocarbons.

[0063] Example 2 As shown in Table 3, the catalyst according to Example 2 uses the same carrier 1 as the catalyst according to Example 1, but differs in that the alkali metal added is potassium instead of sodium. The catalyst system according to Example 2 further improves the C5+ selectivity and C5+ yield compared to the catalyst system according to Example 1.

[0064] [Table 3]

[0065] (Comparative Example 5) As shown in Table 1, the carrier 6 according to Comparative Example 5 is a ZnFe2O4 carrier with a spinel structure and a specific surface area of ​​33.9 m 2 / g, pore volume 0.017 cm 3 / g. Here, ZnFe2O4 with a spinel structure has the same AB2O4 crystal structure as Fe3O4, with Zn occupying the A site. It is said that in ZnFe2O4 with a spinel structure, the proximity of Zn to Fe improves the reducibility of Fe and increases activity. However, as shown in Table 3, Comparative Example 5 exhibits inferior C5+ selectivity and C5+ yield compared to Example 2, which also contained potassium as an alkali metal. In other words, the catalyst system of Example 2 uses Support 1 (ferric oxide), which is different from Support 6 used in the catalyst system of Comparative Example 5, yet achieves performance equal to or better than that of Comparative Example 5.

[0066] (Comparative Example 6) As shown in Table 1, the carrier 7 according to Comparative Example 6 is a carrier made of 100% Fe2O3 (hematite) and has a specific surface area of ​​47.1 m 2 / g, pore volume 0.202 cm 3 / g. In addition, the catalyst system of Comparative Example 6 uses a catalyst in which no alkali metal is supported on the support 7. Therefore, as shown in Table 4, in Comparative Example 6, the C5+ selectivity was 14.8% and the C5+ yield was 2.0%, which indicates that the performance is lower than that of the catalyst system of Example 1.

[0067] [Table 4]

[0068] Example 3 The catalyst system of Example 3 is different from the catalyst system of Example 1 in that the amount of sodium supported on the carrier 1 is 1.6 wt %, but the other components are the same. As shown in Table 4, the catalyst system of Example 3 is equivalent to the catalyst system of Example 1 in C5+ selectivity and C5+ yield.

[0069] Example 4 The catalyst system of Example 3 is different from the catalyst system of Example 1 in that the amount of sodium supported on the carrier 1 is 2.6 wt %, but the other components are the same. As shown in Table 4, the catalyst system of Example 4 has the same C5+ selectivity and C5+ yield as the catalyst system of Example 1.

[0070] Example 5 The catalyst system of Example 5 is different from the catalyst system of Example 2 in that the amount of potassium supported on the carrier 1 is 1.0 wt %, but the other components are the same. As shown in Table 5, the catalyst system of Example 5 has the same C5+ selectivity and C5+ yield as the catalyst system of Example 2.

[0071] [Table 5]

[0072] Example 6 The catalyst system of Example 6 is different from the catalyst system of Example 2 in that the amount of potassium supported on the carrier 1 is 2.0 wt %, but the other components are the same. As shown in Table 5, the catalyst system of Example 6 is equivalent to the catalyst system of Example 2 in C5+ selectivity and C5+ yield.

[0073] A comparison of Comparative Example 6 and Examples 1 to 6 reveals that the C5+ selectivity and C5+ yield are significantly improved by supporting an alkali metal on a support primarily composed of ferric oxide. The amount of alkali metal supported is sufficient to be 0.5 wt% or more, preferably 1.0 wt% or more, and more preferably 1.5 wt% or more. Furthermore, ferric oxide supports supporting potassium as the alkali metal tend to improve C5+ selectivity and C5+ yield more than those supporting sodium.

[0074] Example 7 Next, differences in the alkaline solutions used in the support manufacturing methods will be examined. In the preparation of the iron-based catalyst body in Example 1, sodium hydroxide was used as the alkaline aqueous solution. However, as mentioned above, the iron-based catalyst body in this embodiment requires that the ferric oxide support an alkali metal such as sodium or potassium. If an inconsistent amount of sodium is present in the ferric oxide manufacturing stage, this will affect the washing process and the alkali metal addition process.

[0075] Therefore, in Example 7, when preparing a solution containing a precipitate of iron (III) hydroxide (Fe(OH)3), an aqueous solution containing ammonia but not alkali metal was used to produce Carrier 7. The other steps were essentially the same as those for producing Carrier 1. As shown in Table 1, Carrier 7 is a carrier composed of 100% Fe2O3 (hematite) and has a specific surface area of ​​47.1 m 2 / g, pore volume 0.202 cm 3 The catalyst system of Example 7 using the carrier 7 has the same C5+ selectivity and C5+ yield as the catalyst system of Example 1.

[0076] Furthermore, if the preparation method of carrier 7 in Example 7 is considered as a method for producing a catalyst, this method includes a mixing step of mixing an aqueous solution of iron nitrate with an aqueous solution containing ammonia, a filtration step of filtering a precipitate containing iron (III) hydroxide produced in the mixing step, a generation step of calcining the filtered iron (III) hydroxide to generate ferric oxide, and a step of supporting an alkali metal on the ferric oxide as a carrier. 2 / g or more.

[0077] In this method, compared to when sodium hydroxide or potassium hydroxide is used in the mixing step, the iron(III) hydroxide precipitate produced in the mixing step does not contain alkali metals. If alkali metals are contained in the precipitate, it is necessary to remove as much of the contained alkali metal as possible to improve the accuracy of the amount of alkali metal to be supported in the subsequent support step, which increases production costs. In contrast, according to this embodiment, by using an aqueous solution containing ammonia instead of an alkaline aqueous solution, it is possible to reduce the effort required for cleaning during filtration and the effort required to determine the content of residual alkali metals.

[0078] On the other hand, when a basic aqueous solution containing the same alkali metal as the alkali metal to be supported in the mixing step is used, the amount of alkali remaining in the washing step can be measured, and the amount that is insufficient relative to the predetermined amount of alkali can be supported, thereby shortening the washing step and preventing an increase in production costs.

[0079] Although the present invention has been described above with reference to the above-mentioned embodiments and examples, the present invention is not limited to the above-mentioned embodiments and examples, and appropriate combinations or substitutions of the configurations of the embodiments and examples are also included in the present invention. Furthermore, based on the knowledge of those skilled in the art, it is possible to appropriately rearrange the combinations and processing orders in the embodiments and examples, and to make various design changes and other modifications to the embodiments, and such modified embodiments are also included in the scope of the present invention. [Explanation of symbols]

[0080] 10 reactor, 12 reactor, 12a inlet, 12b outlet, 14 first catalyst, 16 second catalyst.

Claims

1. a reactor configured to discharge hydrocarbons produced from a raw material gas introduced from an upstream inlet through a downstream outlet; a first catalyst for causing a reverse shift reaction, the first catalyst being disposed on the inlet side of the reactor; a second catalyst for causing a Fischer-Tropsch reaction, the second catalyst being disposed on the outlet side of the reactor; the raw material gas contains carbon dioxide and hydrogen, The second catalyst is The catalyst comprises a carrier containing ferric oxide as a main component and an alkali metal supported on the carrier, The carrier has a specific surface area of ​​20 m ２ / g or more of a catalyst system for a Fischer-Tropsch reaction.

2. 2. The catalyst system for a Fischer-Tropsch reaction according to claim 1, wherein the alkali metal in the second catalyst comprises at least one selected from the group consisting of sodium and potassium.

3. The support in the second catalyst has a specific surface area of ​​40 m ２ / g or more, and the pore volume is 0.15 cm ３ 3. The catalyst system for a Fischer-Tropsch reaction according to claim 1, wherein the SiO2 content is 1 / g or more.

4. 2. The catalyst system for a Fischer-Tropsch reaction according to claim 1, wherein the first catalyst comprises copper and zinc oxide.

5. 2. The catalyst system for a Fischer-Tropsch reaction according to claim 1, wherein the first catalyst contains rhodium.

6. 2. The catalyst system for a Fischer-Tropsch reaction according to claim 1, wherein the first catalyst contains platinum.

7. 2. The catalyst system for a Fischer-Tropsch reaction according to claim 1, wherein the first catalyst contains iron-chromium.

8. 8. The catalyst system for a Fischer-Tropsch reaction according to claim 1, further comprising a temperature adjustment mechanism between the first catalyst and the second catalyst, which adjusts the temperature of at least one of the first catalyst and the second catalyst.

Images