Dehydrogenation catalyst, pyrolysis tube for olefin production, and olefin production method

Abstract

To realize a dehydrogenation catalyst having high catalytic activity in pyrolysis reaction of hydrocarbon raw material.SOLUTION: A dehydrogenation catalyst (4) is represented by general formula M11-xM2xOy, where M1 is at least one element selected from a first group consisting of Ce, Sr, Ca, La and Ba, where M2 is at least one element selected from a second group consisting of Co, Fe, Cr and Mn, and where x is from 0.01 to 0.5.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to dehydrogenation catalysts and the like.

Background Art

[0002] Olefins such as ethylene and propylene are used in the industry to produce a wide variety of synthetic chemical products. Olefins are produced by flowing hydrocarbons such as ethane and naphtha derived from petroleum through a pyrolysis tube (cracking tube) and heating them to 700 to 900 °C for thermal decomposition in the gas phase. In the above production method, a large amount of energy is required to reach a high temperature. Therefore, a technique of supporting a dehydrogenation catalyst on the inner surface of the pyrolysis tube is known.

[0003] Patent Document 1 discloses a dehydrogenation catalyst containing, as a catalyst component, at least one selected from the group consisting of oxides of metal elements in Group 2B, oxides of metal elements in Group 3B, and oxides of metal elements in Group 4B of the periodic table.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the dehydrogenation catalyst described in Patent Document 1, sufficient performance may not be obtained depending on the production conditions of olefins, and further development of dehydrogenation catalysts is desired.

[0006] One aspect of the present invention has been made in view of the above problems, and an object thereof is to provide a dehydrogenation catalyst having high catalytic ability in the thermal decomposition reaction of hydrocarbon raw materials.

Means for Solving the Problems

[0007] To solve the above problems, a dehydrogenation catalyst according to one embodiment of the present invention has the general formula M1 1-x M2 x O y wherein M1 is at least one element selected from the first group consisting of Ce, Sr, Ca, La, and Ba, M2 is at least one element selected from the second group consisting of Co, Fe, Cr, and Mn, and x is 0.01 to 0.5.

Advantages of the Invention

[0008] According to one embodiment of the present invention, a dehydrogenation catalyst having high catalytic activity in the thermal decomposition reaction of hydrocarbon raw materials can be realized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

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Figure 8

Mode for Carrying Out the Invention

[0010] 〔Embodiment 1〕 Hereinafter, the pyrolysis tube 1A for olefin production and the dehydrogenation catalyst 4 in Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing the configuration of the pyrolysis tube 1A for olefin production in this embodiment. FIG. 2 is an enlarged view of the inner surface of the pyrolysis tube 1A for olefin production.

[0011] As shown in FIGS. 1 and 2, the pyrolysis tube 1A for olefin production has an alumina film 3 formed on the inner surface of the surface of a tubular base material 2 and a plate-like body (insert material) 5. The base material 2 and the plate-like body 5 are made of a heat-resistant metal material. The alumina film 3 is a metal oxide film containing Al2O3. A dehydrogenation catalyst 4 is supported on the surface of the alumina film 3. In the present application, a metal oxide film containing Al2O3 is referred to as an "alumina film". By having the above configuration, the pyrolysis tube 1A for olefin production can improve the olefin yield from hydrocarbon raw materials such as ethane and naphtha by adding a dehydrogenation catalyst reaction to the pyrolysis reaction. Hereinafter, the base material 2, the plate-like body 5, the alumina film 3, and the dehydrogenation catalyst 4 in the pyrolysis tube 1A for olefin production will be described in detail.

[0012] (Base material 2 and plate-like body 5) The base material 2 in this embodiment is a casting made of a heat-resistant metal material with an alumina film 3 formed on the surface of the base material 2. The plate-like body 5 in this embodiment is a casting made of a heat-resistant metal material provided inside the base material 2 and having an alumina film 3 formed on the surface of the plate-like body 5, or a stainless steel plate. In this embodiment, the pyrolysis tube 1A for olefin production includes the plate-like body 5, but the plate-like body 5 is not an essential member and may not be included. The base material 2 and the plate-like body 5 may be, for example, castings of conventionally known heat-resistant metal materials, and are preferably castings made of heat-resistant metal materials containing at least chromium (Cr), nickel (Ni), and aluminum (Al).

[0013] In this embodiment, the alumina film 3 is formed on the inner surface of the base material 2 and the surface of the plate-like body 5, but the alumina film 3 may be formed only on the inner surface of the base material 2, or the alumina film 3 may be formed only on the surface of the plate-like body 5. Also, in this embodiment, the dehydrogenation catalyst 4 is supported on the inner surface of the base material 2 and the surface of the plate-like body 5, but the dehydrogenation catalyst 4 may be supported only on the inner surface of the base material 2, or the dehydrogenation catalyst 4 may be supported only on the surface of the plate-like body 5.

[0014] It is preferable that at least a part of the inner surface of the base material 2 and / or the surface of the plate-like body 5 constitutes a concave portion and / or a convex portion. Thereby, the heat transfer efficiency can be improved, and the fluid in the tubular base material 2 can be uniformly heated.

[0015] (Alumina film 3) The alumina film 3 has high density and serves as a barrier to prevent the intrusion of oxygen, carbon, and nitrogen from the outside into the base material 2 and the plate-like body 5. In a general pyrolysis tube for olefin production, no metal oxide film is formed on the inner surface of the base material 2 and the surface of the plate-like body 5. Therefore, due to the catalytic action of elements such as nickel (Ni), iron (Fe), and cobalt (Co) on the surfaces of the base material 2 and the plate-like body 5, excessive decomposition of the hydrocarbon raw material occurs during pyrolysis, and coke is generated on the inner surface of the base material 2 and the surface of the plate-like body 5. When the coke generated on the inner surface of the base material 2 and the surface of the plate-like body 5 accumulates, the heat transfer resistance increases, and there is a problem that the temperature on the outer surface of the pyrolysis tube for olefin production rises in order to maintain the reaction temperature inside the olefin pyrolysis tube. Also, when coke accumulates on the inner surface of the base material 2 and the surface of the plate-like body 5, the cross-sectional area of the flow path through which the gas passes becomes smaller, resulting in an increase in pressure loss. For these reasons, in a general pyrolysis tube for olefin production, it was necessary to frequently remove (decoking) the deposited coke.

[0016] In contrast, in the olefin production pyrolysis tube 1A of the present embodiment, by forming the alumina film 3 on the inner surface of the base material 2 and the surface of the plate-like body 5, it is possible to suppress the generation of coke on the inner surface of the base material 2 and the surface of the plate-like body 5. As a result, the frequency of decoking can be reduced.

[0017] The alumina film 3 of the present invention is formed by a surface treatment step and a first heat treatment step. The surface treatment step is a step of performing surface treatment on the target parts of the base material 2 and the plate-like body 5 that come into contact with the high-temperature atmosphere during product use, and adjusting the surface roughness of the parts. The surface treatment of the base material 2 and the plate-like body 5 can exemplify polishing treatment. The surface treatment can be carried out so that the surface roughness (Ra) of the target part is 0.05 to 2.5 μm. More preferably, the surface roughness (Ra) is 0.5 to 2.0 μm. Also, at this time, by adjusting the surface roughness by surface treatment, the residual stress and strain in the heat-affected zone can be removed at the same time.

[0018] The first heat treatment step is a step of heat-treating the base material 2 and the plate-like body 5 after the surface treatment step in an oxidizing atmosphere. The oxidizing atmosphere is an oxidizing gas containing 20% by volume or more of oxygen, or an oxidizing environment in which steam or CO2 is mixed. Further, the heat treatment is performed at a temperature of 900°C or higher, preferably 1000°C or higher, and the heating time is 1 hour or more.

[0019] By sequentially performing the surface treatment step and the first heat treatment step on the base material 2 and the plate-like body 5 as described above, a pyrolysis tube for olefin production in which the alumina film 3 is stably formed on the inner surface of the base material 2 and the surface of the plate-like body 5 can be manufactured.

[0020] The thickness of the alumina film 3 formed on the inner surface of the base material 2 and the surface of the plate-like body 5 is preferably formed to be 0.5 μm or more and 6 μm or less in order to effectively exhibit the barrier function. If the thickness of the alumina film 3 is less than 0.5 μm, the carburization resistance may decrease. If the thickness of the alumina film 3 exceeds 6 μm, the alumina film 3 may be easily peeled off due to the difference in the thermal expansion coefficients of the base material 2 and the plate-like body 5 and the film. From the above, the thickness of the alumina film 3 is more preferably 0.5 μm or more and 2.5 μm or less.

[0021] Note that a chromium oxide scale may be partially formed on the alumina film 3. The reason is that the chromium oxide scale formed near the surfaces of the base material 2 and the plate-like body 5 is pushed up to the product surface by Al2O3. It is preferable that this chromium oxide scale is less, and the area thereof is less than 20% of the product surface, so that Al2O3 occupies 80% or more of the area.

[0022] (Dehydrogenation catalyst 4) The dehydrogenation catalyst 4 is a dehydrogenation catalyst used for olefin production. The dehydrogenation catalyst 4 is a catalyst for improving the yield of olefins in a pyrolysis reaction using the olefin production pyrolysis tube 1A (specifically, a reaction of thermally decomposing a hydrocarbon raw material such as naphtha or ethane into olefins), and is supported on the surface of the alumina film 3.

[0023] The dehydrogenation catalyst 4 contains at least one element selected from the first group consisting of Ce, Sr, Ca, La, and Ba (hereinafter also referred to as the first group element), and at least one element selected from the second group consisting of Co, Fe, Cr, and Mn (hereinafter also referred to as the second group element). Further, when the sum of the total molar ratio of the first group elements and the total molar ratio of the second group elements is 1, the total molar ratio of the second group elements is 0.01 to 0.5. By having such a configuration, the dehydrogenation catalyst 4 can easily take in and release oxygen in its structure. As a result, the dehydrogenation reaction of the hydrocarbon raw material can be promoted, and thus it has high catalytic activity in the dehydrogenation reaction.

[0024] The dehydrogenation catalyst 4 can also be expressed as follows. That is, the dehydrogenation catalyst 4 is represented by the general formula M1 1-x M2 x O y wherein M1 is at least one element selected from the first group consisting of Ce, Sr, Ca, La, and Ba, M2 is at least one element selected from the second group consisting of Co, Fe, Cr, and Mn, and x is 0.01 to 0.5. The lower limit of x is preferably 0.1. Also, the upper limit of x is preferably 0.4, more preferably 0.2. The value of y is a value determined by the first group elements and the second group elements.

[0025] For the dehydrogenation catalyst 4, it is preferable that the element selected from the first group is Ce and the element selected from the second group is Co. By having such a configuration, the catalytic activity in the dehydrogenation reaction is further improved. Also, in the case of such a configuration, when the sum of the molar ratio of Ce and the molar ratio of Co is 1, the molar ratio of Co is preferably 0.1 to 0.4. In this case, the dehydrogenation catalyst 4 can be represented as Ce 1-x Co x O2 (x is 0.1 to 0.4).

[0026] <Method for Producing Dehydrogenation Catalyst 4> The method for producing dehydrogenation catalyst 4 is not particularly limited, and for example, it can be produced by a citric acid complex method, a solid-phase method, or the like. Hereinafter, a method for producing dehydrogenation catalyst 4 using the citric acid complex method and the solid-phase method will be described.

[0027] (Citric Acid Complex Method) The citric acid complex method includes a mixing and stirring step, a drying step, a calcination step, and a final firing step.

[0028] In the mixing and stirring step, a salt containing the elements constituting dehydrogenation catalyst 4 (for example, nitrate, acetate, etc.), citric acid monohydrate, ethylene glycol, and distilled water are mixed to obtain a mixed solution. The salt is weighed so that the Group 1 elements and Group 2 elements have a desired molar ratio. It is preferable to add citric acid monohydrate in an amount 3 to 4 times the total molar amount of the Group 1 elements and Group 2 elements contained in the salt. It is preferable to add ethylene glycol in an amount 3 to 4 times the total molar amount of the Group 1 elements and Group 2 elements contained in the salt. It is preferable to add distilled water in an amount 1200 to 1600 times the total molar amount of the Group 1 elements and Group 2 elements contained in the salt. The mixed solution is preferably stirred at 60 to 70 °C for 10 to 17 hours.

[0029] In the drying step, the mixed solution is dried to obtain a powder. For example, it may be dried by heating with stirring on a hot plate.

[0030] In the calcination step, the powder is calcined to obtain a calcined body. The calcination step is carried out in air or oxygen, and the calcination temperature is preferably 400 to 450 °C, and the holding time is preferably 2 to 3 hours. The calcination temperature and the holding time may be appropriately adjusted according to the amount of the catalyst to be prepared within this range.

[0031] In this firing process, the green compact is fired to obtain an oxide. This firing process is carried out in air or oxygen, and the firing temperature is preferably 850 to 900 °C, and the holding time is preferably 8 to 12 hours. The firing temperature and the holding time may be appropriately adjusted according to the amount of the catalyst to be prepared within this range.

[0032] (Solid-phase method) The solid-phase method includes a pulverization and mixing process, a drying process, and a firing process.

[0033] In the pulverization and mixing process, compounds containing the elements constituting the dehydrogenation catalyst 4 (for example, oxides, carbonate compounds) are mixed, and the mixture is pulverized and mixed to obtain a pulverized and mixed powder. The compounds are mixed so that the Group 1 element and the Group 2 element have a desired molar ratio. For example, they may be pulverized and mixed by a wet bead mill.

[0034] In the drying process, the pulverized and mixed powder is dried to obtain a dried body. In the firing process, the dried body is fired to obtain an oxide. The firing process is carried out in air or oxygen, and the firing temperature is preferably 500 to 1300 °C, and the holding time is preferably 1 to 10 hours. The firing temperature and the holding time may be appropriately adjusted according to the amount of the catalyst to be prepared within this range.

[0035] ><Method for supporting the dehydrogenation catalyst 4> Next, the method for supporting the dehydrogenation catalyst 4 on the alumina film 3 will be described. The method for supporting the dehydrogenation catalyst 4 on the alumina film 3 includes a coating process and a second heat treatment process. The coating process and the second heat treatment process will be described in detail below.

[0036] (a) Coating process The coating process is a process of coating a slurry containing the dehydrogenation catalyst 4 previously produced on the surface of the alumina film 3 formed by the surface treatment process and the first heat treatment process.

[0037] (b) Second heat treatment process The second heat treatment process is a process of heat-treating the base material 2 and the plate-like body 5 on which the slurry is coated on the alumina film 3 by the coating process.

[0038] The heat treatment in the second heat treatment step is carried out in the atmosphere or in an acidic atmosphere. The heat treatment temperature in the second heat treatment step is in the range of 500 to 900 °C, and the heat treatment time is 1 to 6 hours.

[0039] By performing the second heat treatment step under the above heat treatment conditions, the dehydrogenation catalyst 4 can be supported on the alumina film 3.

[0040] Note that by adjusting the concentration of the slurry applied in the above coating step, the dehydrogenation catalyst 4 can be supported on the alumina film 3 at an appropriate concentration (amount).

[0041] Thus, in the pyrolysis tube 1A for olefin production according to the present embodiment, an alumina film 3 is formed on the inner surface of the tubular base material 2 made of a heat-resistant metal material and the surface of the plate-like body 5, and a dehydrogenation catalyst 4 is supported on the surface of the alumina film 3.

[0042] According to the above configuration, in the pyrolysis tube 1A for olefin production of the present invention, an alumina film 3 is formed on the inner surface of the base material 2 and the surface of the plate-like body 5. Therefore, it is possible to suppress the generation of coke on the surface of the alumina film 3 (the base material 2 and the plate-like body 5). And a dehydrogenation catalyst 4 is supported on the surface of this alumina film 3. Thereby, when the dehydrogenation catalyst 4 acts as a dehydrogenation catalyst in the pyrolysis using the pyrolysis tube 1A for olefin production, for example, ethylene can be generated from ethane by a dehydrogenation reaction. As a result, the yield of olefins from hydrocarbon raw materials such as ethane and naphtha by pyrolysis can be improved.

[0043] In this embodiment, the dehydrogenation catalyst 4 is supported on the alumina film 3 formed on the inner surface of the base material 2 and the surface of the plate-like body 5 by performing a surface treatment step and a first heat treatment step, followed by a coating step and a second heat treatment step. However, the pyrolysis tube for olefin production of the present invention is not limited to this. For example, after performing the surface treatment step, the coating step and the heat treatment step may be performed. In this case, in the heat treatment step, the alumina film 3 is formed on the inner surface of the base material 2 and the surface of the plate-like body 5, and the dehydrogenation catalyst 4 is supported on the alumina film 3. As a result, by performing the heat treatment step only once, the alumina film 3 can be formed on the inner surface of the base material 2 and the surface of the plate-like body 5, and the dehydrogenation catalyst 4 can be supported on the alumina film 3.

[0044] In this embodiment, the dehydrogenation catalyst 4 is supported on the surface of the alumina film 3 formed on the inner surface of the base material 2 and the surface of the plate-like body 5. However, the pyrolysis tube 1A for olefin production of the present invention is not limited to this. That is, the pyrolysis tube for olefin production of the present invention may have a structure in which the dehydrogenation catalyst 4 is supported on the surface of a metal oxide film different from Al2O3 (for example, Cr2O3, MnCr2O4, etc.) that has a barrier function and can support the dehydrogenation catalyst 4.

[0045] A method for producing an olefin according to an aspect of the present invention is a method for producing an olefin using the above-described pyrolysis tube 1A for olefin production. Examples of the olefin include ethylene, propylene, and the like. Examples of the hydrocarbon raw material include ethane, naphtha, and the like. The olefin is produced by flowing the hydrocarbon raw material through the pyrolysis tube 1A for olefin production and heating it to 700 to 900°C for thermal decomposition in the gas phase.

[0046] 〔Embodiment 2〕 Another embodiment of the present invention will be described below. For convenience of explanation, members having the same functions as those described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

[0047] FIG. 3 is a schematic cross-sectional view showing the configuration of the pyrolysis tube 1B for olefin production in the present embodiment. FIG. 4 is an enlarged view of the inner surface of the pyrolysis tube 1B for olefin production.

[0048] In the pyrolysis tube 1A for olefin production in Embodiment 1, an alumina film 3 as a metal oxide film containing Al2O3 was formed on the inner surface of the base material 2 and the surface of the plate-like body 5, and a dehydrogenation catalyst 4 was supported on the surface of the alumina film 3. In contrast, the pyrolysis tube 1B for olefin production in the present embodiment is different from the pyrolysis tube 1A for olefin production in that the dehydrogenation catalyst 4 is directly supported on the inner surface of the tubular base material 2 made of a heat-resistant metal material and the surface of the plate-like body 5, as shown in FIGS. 3 and 4.

[0049] The pyrolysis tube 1B for olefin production can be manufactured by applying a slurry containing the pre-manufactured dehydrogenation catalyst 4 to the inner surface of the base material 2 and the surface of the plate-like body 5, and performing heat treatment under appropriate conditions such as an air or nitrogen atmosphere to support the dehydrogenation catalyst 4 on the inner surface of the base material 2 and the surface of the plate-like body 5.

[0050] As described above, the dehydrogenation catalyst 4 is supported on the inner surface of the base material 2 and the surface of the plate-like body 5 in the pyrolysis tube 1B for olefin production. Thereby, when the dehydrogenation catalyst 4 acts as a dehydrogenation catalyst in the pyrolysis using the pyrolysis tube 1B for olefin production, for example, ethylene can be produced from ethane by a dehydrogenation reaction. As a result, the yield of olefins from hydrocarbon raw materials such as ethane and naphtha by pyrolysis can be improved.

[0051] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Example

[0052] The dehydrogenation catalysts of Examples 1 to 8 as examples of the dehydrogenation catalyst of the present invention and the dehydrogenation catalyst of Comparative Example 1 as a comparative example will be described below. First, the production methods of the dehydrogenation catalysts of Examples 1 to 8 and Comparative Example 1 will be described below.

[0053] (Example 1) The dehydrogenation catalyst of Example 1 was prepared by the citrate complex method. Specifically, first, cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and chromium nitrate (Cr(NO3)3) were weighed so as to have a molar ratio of Ce:Cr = 0.9:0.1 and used as solutes. Citric acid monohydrate and ethylene glycol in a molar amount three times that of the total molar amount of Ce and Cr in the solute were dissolved in distilled water in a molar amount 1500 times that of the total molar amount and stirred well (hereinafter referred to as the solvent). The solute was mixed with the solvent and heated and stirred overnight at 70°C. Then, it was heated and dried while stirring on a hot plate to obtain a powder. The powder was calcined at 400°C for 2 hours and then sintered at 850°C for 10 hours to obtain Ce 0.9 Cr 0.1 O2.

[0054] (Example 2) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and manganese nitrate hexahydrate (Mn(NO3)2·6H2O) were weighed so as to have a molar ratio of Ce:Mn = 0.9:0.1 and used as solutes, and in the same manner as in Example 1, Ce 0.9 Mn 0.1 O2 as the dehydrogenation catalyst of Example 2 was prepared.

[0055] (Example 3) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and iron nitrate (Fe(NO3)3) were weighed so as to have a molar ratio of Ce:Fe = 0.9:0.1 and used as solutes, and in the same manner as in Example 1, Ce 0.9 Fe 0.1 O2 as the dehydrogenation catalyst of Example 3 was prepared.

[0056] (Example 4) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and cobalt nitrate (Co(NO3)2) were weighed so as to have a molar ratio of Ce:Co = 0.9:0.1 to obtain a solute, and then in the same manner as in Example 1, Ce 0.9 Co 0.1 O2 was prepared.

[0057] (Example 5) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and nickel nitrate hexahydrate (Ni(NO3)2·6H2O) were weighed so as to have a molar ratio of Ce:Ni = 0.9:0.1 to obtain a solute, and then in the same manner as in Example 1, Ce 0.9 Ni 0.1 O2 was prepared.

[0058] (Example 6) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and cobalt nitrate (Co(NO3)2) were weighed so as to have a molar ratio of Ce:Fe = 0.8:0.2 to obtain a solute, and then in the same manner as in Example 1, Ce 0.8 Co 0.2 O2 was prepared.

[0059] (Example 7) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and cobalt nitrate (Co(NO3)2) were weighed so as to have a molar ratio of Ce:Fe = 0.7:0.3 to obtain a solute, and then in the same manner as in Example 1, Ce 0.7 Co 0.3 O2 was prepared.

[0060] (Example 8) Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) and cobalt nitrate (Co(NO3)2) were weighed so as to have a molar ratio of Ce:Fe = 0.6:0.4 to obtain a solute, and then in the same manner as in Example 1, Ce 0.6 Co 0.4 O2 was prepared.

[0061] (Comparative Example 1) The dehydrogenation catalyst of Comparative Example 1 was prepared by the citric acid complex method. Cerium nitrate hexahydrate (Ce(NO3)3·6H2O) was used as the solute, and citric acid monohydrate and ethylene glycol in a molar amount three times that of Ce in the solute were dissolved in distilled water in a molar amount 1500 times that of the total molar amount and stirred well (hereinafter referred to as the solvent). The solute was mixed with the solvent and heated with stirring overnight at 70 °C. Then, it was heated and dried with stirring on a hot plate to obtain a powder. The powder was calcined at 400 °C for 2 hours and then sintered at 850 °C for 10 hours to prepare CeO2.

[0062] <Pyrolysis Experiment of Ethane> Next, the pyrolysis experiment of ethane performed using the dehydrogenation catalysts of Examples 1 to 5 and Comparative Example 1 will be described. In the pyrolysis experiment of ethane, first, a mixture of 100 mg of the dehydrogenation catalyst and 392 mg of SiC, which is an inert solid, was filled in a quartz tube (inner diameter 4 mm, length 180 mm) to a height of 30 mm. Next, the quartz tube was inserted into a tubular furnace, and the temperature inside the tubular furnace was raised to 600 °C. Next, a raw material gas adjusted to have a volume ratio of ethane (C2H6): steam (H2O): nitrogen (N2) = 1.0: 1.4: 5.6 was supplied to the quartz tube at a flow rate of 118 mL / min to carry out the pyrolysis reaction of ethane. Among the gases flowing out of the quartz tube, hydrogen (H2) and nitrogen (N2) were analyzed with a TCG gas chromatograph (Shimadzu, GC-8A). Also, among the gases flowing out of the quartz tube, ethane (C2H6), ethylene (C2H4), carbon monoxide (CO), and methane (CH4) were analyzed with an FID gas chromatograph (Shimadzu, GC-8A) equipped with a methanizer. And from these analysis results, the production rate of ethylene (C2H4), the conversion rate of ethane (C3H6), and the selectivity of ethylene (C2H4) were calculated.

[0063] Figure 5 is a graph showing the ethylene production rate when pyrolysis experiments were conducted using the dehydrogenation catalysts of Examples 1 to 5 and Comparative Example 1. Figure 6 is a graph created using the data obtained from the pyrolysis experiments using the dehydrogenation catalysts of Examples 1 to 4 and Comparative Example 1, with the ethane conversion rate on the horizontal axis and the ethylene selectivity on the vertical axis. Figures 5 and 6 are graphs created using the data obtained by conducting pyrolysis experiments using the dehydrogenation catalyst represented by Ce 0.9 M 0.1 O2 (where M is a Group 2 element), and the dehydrogenation catalyst of Comparative Example 1.

[0064] As shown in Figure 5, when using the dehydrogenation catalysts of Examples 1 to 5 containing Ce and a Group 2 element, the ethylene production rate was higher than when using the dehydrogenation catalyst of Comparative Example 1 that does not contain a Group 2 element. In particular, the ethylene production rate was the highest when using the dehydrogenation catalyst of Example 4 containing Co.

[0065] As shown in Figure 6, when using the dehydrogenation catalysts of Examples 1 to 5 containing Ce and a Group 2 element, the ethane conversion rate was higher than when using the dehydrogenation catalyst of Comparative Example 1 that does not contain a Group 2 element. Also, when using the dehydrogenation catalysts of Examples 2 to 4 containing Mn, Fe, or Co as the Group 2 element, the ethylene selectivity was higher than when using the dehydrogenation catalyst of Comparative Example 1.

[0066] Figure 7 is a graph showing the ethylene production rate when pyrolysis experiments were conducted using the dehydrogenation catalysts of Example 4, Examples 6 to 8, and Comparative Example 1. Figure 8 is a graph created using the data obtained from the pyrolysis experiments using the dehydrogenation catalysts of Example 4, Examples 6 to 8, and Comparative Example 1, with the ethane conversion rate on the horizontal axis and the ethylene selectivity on the vertical axis. Figures 7 and 8 are graphs created using the data obtained by conducting pyrolysis experiments using the dehydrogenation catalyst represented by Ce 1-x Co x O2, and the dehydrogenation catalyst of Comparative Example 1.

[0067] As shown in Fig. 7, when using the dehydrogenation catalysts of Examples 4 and 6 - 8 containing Ce and Co, the production rate of ethylene was higher than that when using CeO2, the dehydrogenation catalyst of Comparative Example 1. In particular, when using the dehydrogenation catalyst of Example 6, which is Ce 0.8 Co 0.2 O2, the production rate of ethylene was the highest.

[0068] As shown in Fig. 8, when using the dehydrogenation catalysts of Examples 4 and 6 - 8 containing Ce and Co, both the conversion rate of ethane and the selectivity of ethylene were higher than those when using CeO2, the dehydrogenation catalyst of Comparative Example 1. In particular, when using the dehydrogenation catalyst of Example 6, which is Ce 0.8 Co 0.2 O2, the conversion rate of ethane and the selectivity of ethylene were the highest.

Description of Reference Numerals

[0069] 1A, 1B Pyrolysis tubes for olefin production 2 Base material 3 Alumina film (metal oxide film) 4 Dehydrogenation catalyst 5 Plate - like body

Claims

1. M1 in general formula １－ｘ M2 ｘ O ｙ represented by The above M1 is at least one element selected from the first group consisting of Ce, Sr, Ca, La, and Ba, The above M2 is at least one element selected from the second group consisting of Co, Fe, Cr, and Mn, The above x is from 0.01 to 0.5, The element selected from the first group is Ce, The element selected from the second group is Co, A dehydrogenation catalyst.

2. The dehydrogenation catalyst according to Claim 1, wherein the above x is from 0.1 to 0.

4.

3. The dehydrogenation catalyst according to Claim 1 or 2 is supported on the inner surface of a tubular base material made of a heat-resistant metal material and / or the surface of a plate-shaped body made of a heat-resistant metal material, A pyrolysis tube for olefin production.

4. A method for producing an olefin, which comprises producing an olefin using the pyrolysis tube for olefin production according to Claim 3.

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