Method for producing cyclopentadiene

Abstract

A method for producing cyclopentadiene according to one aspect of the present disclosure includes a dehydrogenation step for obtaining cyclopentadiene by bringing a dehydrogenation catalyst into contact with a raw material component containing at least one type selected from the group consisting of an n-hydrocarbon having 5 carbon atoms, cyclopentane and cyclopentene. The dehydrogenation catalyst contains: a metal oxide carrier containing Al and a group 2 metal element; and Pt supported on said carrier.

Description

[Technical Field]

[0001] The present disclosure relates to a process for producing cyclopentadiene. [Background technology]

[0002] Conventionally, cyclopentadiene has been obtained as a by-product of ethylene crackers. However, since its supply is limited, there is a demand for the targeted production of cyclopentadiene. For example, Non-Patent Document 1 describes a method for producing cyclopentadiene from n-pentane, n-pentene, etc. using a Pt / SiO2 catalyst. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] V. Sh. Fel'dblyum et al., Doklady Chemistry, 424(2), 27-30 (2009) Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been reported in Non-Patent Document 1 that the catalyst deteriorates in a short period of time (for example, within 15 minutes) in the method described in Non-Patent Document 1. Therefore, although the method described in Non-Patent Document 1 can provide a high yield of cyclopentadiene within the first few minutes while the activity of the catalyst is maintained, it is problematic in that a high yield cannot be obtained when the reaction is carried out for a long period of time (more than 15 minutes).

[0005] Therefore, an object of the present disclosure is to provide a method for producing cyclopentadiene that can produce cyclopentadiene in high yield even when the reaction is carried out for a long period of time. [Means for solving the problem]

[0006] One aspect of the present disclosure relates to a method for producing cyclopentadiene, comprising a dehydrogenation step of contacting a feedstock component containing at least one selected from the group consisting of a normal isomer of a hydrocarbon having 5 carbon atoms, cyclopentane, and cyclopentene with a dehydrogenation catalyst to obtain cyclopentadiene, wherein the dehydrogenation catalyst has a metal oxide support containing Al and a Group 2 metal element, and a supported metal containing Pt supported on the support.

[0007] In one embodiment, the content of the Group 14 metal element in the dehydrogenation catalyst may be 1.0 mass % or less based on the total amount of the dehydrogenation catalyst.

[0008] In one embodiment, the molar ratio of the Group 14 metal element to the Pt in the dehydrogenation catalyst (number of moles of Group 14 metal element / number of moles of Pt) may be 1.0 or less.

[0009] In one embodiment, the content of the Pt in the dehydrogenation catalyst may be 0.1 to 10 mass % based on the total amount of the dehydrogenation catalyst.

[0010] In one embodiment, the Group 2 metal element may include Mg.

[0011] In one embodiment, the dehydrogenation step may be carried out in an atmosphere containing hydrogen. [Effects of the Invention]

[0012] According to the present disclosure, there is provided a method for producing cyclopentadiene that can produce cyclopentadiene in high yield even when the reaction is carried out for a long period of time. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a graph showing the yields of main components contained in the reaction products obtained in Example 1 and Comparative Examples 1 to 4. [Figure 2] 1 is a graph showing the yields of main components contained in the reaction products obtained in Example 2 and Comparative Example 5. [Figure 3]1 is a graph showing the yields of main components contained in the reaction products obtained in Examples 2 to 8. [Figure 4] 1 is a graph showing the yields of main components contained in the reaction products obtained in Examples 2 and 9 to 12. [Figure 5] 1 is a graph showing the yields of main components contained in the reaction products obtained in Examples 13 to 17. [Figure 6] 1 is a graph showing the yields of main components contained in the reaction products obtained in Examples 18 to 22. [Figure 7] 1 is a graph showing the yields of main components contained in the reaction products obtained in Examples 2 and 23 to 27. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present disclosure will be described in detail below.

[0015] <Method of producing cyclopentadiene> The method for producing cyclopentadiene according to this embodiment includes a dehydrogenation step of contacting a raw material component containing at least one selected from the group consisting of a normal isomer of a hydrocarbon having 5 carbon atoms, cyclopentane, and cyclopentene with a dehydrogenation catalyst to obtain cyclopentadiene.

[0016] The raw material components may be, for example, a hydrocarbon mixture containing at least one selected from the group consisting of normal hydrocarbons having 5 carbon atoms, cyclopentane, and cyclopentene as a main component (e.g., 70% by mass or more). The total amount of at least one selected from the group consisting of normal hydrocarbons having 5 carbon atoms, cyclopentane, and cyclopentene in the raw material components is preferably 80% by mass or more, more preferably 90% by mass or more, and may even be 100% by mass. Cyclopentane and cyclopentenes are particularly preferred as raw material components. A high content of cyclopentane and cyclopentenes can further improve the yield of cyclopentadiene. The total amount of cyclopentane and cyclopentene in the raw material components is preferably 5% by mass or more, more preferably 20% by mass or more, and may even be 50% by mass or more.

[0017] Examples of normal isomers of hydrocarbons having 5 carbon atoms include n-pentane, 1-pentene, 2-pentene, 1,3-pentadiene, and 1,4-pentadiene. When the raw material component contains normal isomers of hydrocarbons having 5 carbon atoms, a cyclization dehydrogenation reaction of these hydrocarbons takes place in the dehydrogenation step.

[0018] The conditions for the dehydrogenation reaction are not particularly limited as long as they are conditions that can convert at least one selected from the group consisting of the normal form of the hydrocarbon having 5 carbon atoms, cyclopentane, and cyclopentene into cyclopentadiene.

[0019] The dehydrogenation catalyst has a support and a supported metal supported on the support.

[0020] The support is a metal oxide support containing Al and a Group 2 metal element. The Group 2 metal element refers to a metal element belonging to Group 2 of the long-form periodic table of the elements defined by IUPAC (International Union of Pure and Applied Chemistry). The Group 2 metal element may be, for example, at least one selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). By including Al and a Group 2 metal element in the support, deterioration of the dehydrogenation catalyst can be suppressed in the dehydrogenation step, and cyclopentadiene can be produced in high yield even when the reaction is carried out for a long period of time (more than 15 minutes). From the viewpoints of further suppressing catalyst deterioration and further improving the yield of cyclopentadiene, the support preferably contains Mg as the Group 2 metal element.

[0021] The supported metal contains Pt, and may or may not contain metal elements other than Pt.

[0022] In the dehydrogenation catalyst of this embodiment, the Al content may be 15% by mass or more, or 25% by mass or more, based on the total mass of the dehydrogenation catalyst. The Al content may be 40% by mass or less. When the Al content is 15% by mass or more and 40% by mass or less, the yield of cyclopentadiene tends to be further improved.

[0023] In the dehydrogenation catalyst of this embodiment, the content of the Group 2 metal element is preferably 10% by mass or more, more preferably 13% by mass or more, based on the total mass of the dehydrogenation catalyst. The content of the Group 2 metal element is preferably 20% by mass or less, more preferably 18% by mass or less, based on the total mass of the dehydrogenation catalyst. When the content of the Group 2 metal element is 10% by mass or more and 20% by mass or less, the yield of cyclopentadiene tends to be further improved.

[0024] In the dehydrogenation catalyst of this embodiment, the Pt content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the total mass of the dehydrogenation catalyst. The Pt content is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, based on the total mass of the dehydrogenation catalyst. When the Pt content is 0.1% by mass or more, the amount of platinum per catalyst amount increases, allowing for a smaller reactor size. Furthermore, when the Pt content is 10% by mass or less, the Pt particles formed on the catalyst have a size suitable for the dehydrogenation reaction, and the platinum surface area per unit platinum weight increases, resulting in a more efficient reaction system.

[0025] In the dehydrogenation catalyst of this embodiment, the content of the Group 14 metal element is preferably 1.0 mass% or less, more preferably 0.6 mass% or less, and even more preferably 0.3 mass% or less, based on the total mass of the dehydrogenation catalyst. The content of the Group 14 metal element may be 0 mass%, 0.01 mass% or more, or 0.05 mass% or more, based on the total mass of the dehydrogenation catalyst. When the content of the Group 14 metal element is 1.0 mass% or less, the yield of cyclopentadiene tends to be further improved. Note that, if the content of the Group 14 metal element in the dehydrogenation catalyst is high, the dehydrogenation reaction by the alloy of Pt and the Group 14 metal element is more likely to occur, and the cyclization reaction product relatively decreases and the non-cyclized dehydrogenation reaction product increases, which tends to decrease the yield of cyclopentadiene. Furthermore, when the content of the Group 14 metal element is 0.01% by mass or more, side reactions are easily suppressed, and the amounts of coke-derived products (methane, carbon monoxide, carbon dioxide), cracking products (hydrocarbons having 2 to 4 carbon atoms), and aromatic products (benzene, toluene, xylene) produced tend to be reduced. Due to the suppression of the side reactions, when the dehydrogenation catalyst contains a small amount of a Group 14 metal element, the yield of cyclopentadiene may be improved compared to when the catalyst does not contain a Group 14 metal element. The Group 14 metal element refers to a metal element belonging to Group 14 of the long-form periodic table of the elements as defined by IUPAC (International Union of Pure and Applied Chemistry). Examples of Group 14 metal elements include germanium (Ge), tin (Sn), and lead (Pb).

[0026] In the dehydrogenation catalyst of this embodiment, the molar ratio of the Group 14 metal element to Pt (number of moles of Group 14 metal element / number of moles of Pt) is preferably 1.0 or less, more preferably 0.7 or less, and even more preferably 0.5 or less. The molar ratio of the Group 14 metal element to Pt may be 0, 0.05 or more, or 0.1 or more. When the molar ratio of the Group 14 metal element to Pt is 1.0 or less, the yield of cyclopentadiene tends to be further improved. Note that when the molar ratio of the Group 14 metal element to Pt is high, the dehydrogenation reaction by the alloy of Pt and the Group 14 metal element is more likely to occur, and the cyclization reaction product relatively decreases and the non-cyclized dehydrogenation reaction product increases, which tends to reduce the yield of cyclopentadiene. Furthermore, when the molar ratio of the Group 14 metal element to Pt is 0.05 or more, side reactions are easily suppressed, and the amounts of coke-derived products (methane, carbon monoxide, carbon dioxide), cracking products (hydrocarbons having 2 to 4 carbon atoms), and aromatic products (benzene, toluene, xylene) produced tend to be reduced. Note that, due to the effect of suppressing the side reactions, when the molar ratio of the Group 14 metal element to Pt is small, the yield of cyclopentadiene may be improved compared to when the molar ratio is 0.

[0027] In the dehydrogenation catalyst of this embodiment, the molar ratio of the Group 2 metal element to Al (moles of Group 2 metal element / moles of Al) is preferably 0.30 or more, and more preferably 0.40 or more, from the viewpoint of suppressing side reactions and further improving reaction efficiency. The molar ratio of the Group 2 metal element to Al is preferably 0.60 or less, and more preferably 0.55 or less, from the viewpoint of improving the dispersibility of Pt in the dehydrogenation catalyst. Furthermore, by setting the molar ratio of the Group 2 metal element to Al within the above range, it is possible to achieve a well-balanced improvement between the effect of suppressing catalyst degradation and the effect of improving the yield of cyclopentadiene.

[0028] The contents of Al, Group 2 metal elements, Group 14 metal elements, and Pt in the dehydrogenation catalyst can be measured using an inductively coupled plasma atomic emission spectrometry (ICP-AES) under the following measurement conditions: The dehydrogenation catalyst is dissolved in an alkali and then dissolved in dilute hydrochloric acid before use. Equipment: Hitachi High-Tech Science SPS-3000 High frequency output: 1.2kw Plasma gas flow rate: 18L / min Auxiliary gas flow rate: 0.4L / min Nebulizer gas flow rate: 0.4L / min

[0029] The specific surface area of ​​the dehydrogenation catalyst of this embodiment may be the same as the specific surface area of ​​the carrier described below.

[0030] The support constituting the dehydrogenation catalyst may be, for example, a support containing alumina (Al2O3) and an oxide of a Group 2 metal, or a composite oxide of Al and a Group 2 metal. The metal oxide support may be a support containing a composite oxide of Al and a Group 2 metal element, or at least one selected from the group consisting of alumina and oxides of Group 2 metal elements. The composite oxide of Al and a Group 2 metal may be, for example, MgAl2O4.

[0031] The Al content in the support may be 20% by mass or more, or 30% by mass or more, based on the total mass of the support. The Al content in the support may be 70% by mass or less, or 60% by mass or less, based on the total mass of the support. An Al content of 20% by mass or more and 70% by mass or less tends to further improve the yield of cyclopentadiene.

[0032] The content of the Group 2 metal element in the support may be 10% by mass or more, or 15% by mass or more, based on the total mass of the support. The content of the Group 2 metal element in the support may be 30% by mass or less, or 20% by mass or less, based on the total mass of the support. A Group 2 metal element content of 10% by mass or more and 30% by mass or less tends to further improve the yield of cyclopentadiene.

[0033] The content of the composite oxide of Al and a Group 2 metal element in the support may be 60 mass% or more, or 80 mass% or more, based on the total mass of the support, and may be 100 mass% or less, or 90 mass% or less, based on the total mass of the support.

[0034] The alumina content in the support may be 10% by mass or more, or 30% by mass or more, based on the total mass of the support, and 90% by mass or less, or 80% by mass or less, based on the total mass of the support.

[0035] The content of the oxide of the Group 2 metal element in the support may be 15% by mass or more, or 25% by mass or more, based on the total mass of the support, and may be 50% by mass or less, or 35% by mass or less, based on the total mass of the support.

[0036] The support may contain other metal elements in addition to Al and Group 2 metal elements. The other metal elements may be, for example, at least one selected from the group consisting of Si, Zr, Ti, Ce, Li, Na, K, Zn, Fe, In, Se, Sb, Ni, and Ga. The other metal elements may be present as oxides or as composite oxides with at least one selected from the group consisting of Al and Group 2 metal elements.

[0037] The acidity of the carrier is preferably near neutral from the viewpoint of suppressing side reactions. Here, the standard for the acidity of the carrier is generally determined by the pH in a state in which the carrier is dispersed in water. That is, in this specification, the acidity of the carrier can be expressed as the pH of a suspension in which 1% by mass of the carrier is suspended. The acidity of the carrier may preferably be pH 5.0 to 9.0, more preferably pH 6.0 to 8.0.

[0038] The specific surface area of ​​the support is, for example, 50 m 2 / g or more, 2 / g or more. This provides the effect of increasing the dispersibility of the supported Pt. In addition, the specific surface area of ​​the support is preferably 300 m 2 / g or less, and 2 / g or less is preferable. Carriers with such a specific surface area tend not to have micropores that are easily crushed when the carrier is fired at high temperatures. Therefore, the dispersibility of the supported Pt tends to increase. The specific surface area of ​​the carrier is measured using a BET surface area meter using the nitrogen adsorption method.

[0039] The method for preparing the support is not particularly limited, and may be, for example, a sol-gel method, a co-precipitation method, a hydrothermal synthesis method, an impregnation method, a solid phase synthesis method, or the like.

[0040] As an example of a method for preparing a support, one embodiment of an impregnation method is shown below. First, a support precursor containing a second metal element (e.g., Al) is added to a solution in which a precursor of a first metal element (e.g., a Group 2 metal element) is dissolved in a solvent, and the solution is stirred. Thereafter, the solvent is removed under reduced pressure, and the resulting solid is dried. The dried solid is calcined to obtain a support containing the first metal element and the second metal element. In this embodiment, the content of the target metal element contained in the support can be adjusted by the concentration of the target metal element in the solution containing the target metal element, the amount of the solution used, etc.

[0041] The metal precursor may be, for example, a salt or complex containing a metal element. The salt containing a metal element may be, for example, an inorganic salt, an organic acid salt, or a hydrate thereof. The inorganic salt may be, for example, a sulfate, a nitrate, a chloride, a phosphate, a carbonate, or the like. The organic salt may be, for example, an acetate, an oxalate, or the like. The complex containing a metal element may be, for example, an alkoxide complex, an ammine complex, or the like.

[0042] Examples of solvents that can dissolve the metal precursor include hydrochloric acid, nitric acid, aqueous ammonia, ethanol, chloroform, and acetone.

[0043] Examples of the carrier precursor containing the second metal element include alumina (e.g., γ-alumina). The carrier precursor can be prepared by, for example, a sol-gel method, a coprecipitation method, a hydrothermal synthesis method, etc. Commercially available alumina may also be used as the carrier precursor.

[0044] The calcination can be carried out, for example, in an air atmosphere or an oxygen atmosphere. The calcination can be carried out in one stage, or in two or more stages. The calcination temperature may be any temperature at which the metal precursor can be decomposed, and may be, for example, 200 to 1000°C, or 400 to 800°C. When calcination is carried out in multiple stages, it is sufficient that at least one stage is at the above-mentioned calcination temperature. The calcination temperatures in the other stages may be, for example, in the same range as above, and may be 100 to 200°C.

[0045] The stirring conditions may be, for example, a stirring temperature of 0 to 60°C and a stirring time of 10 minutes to 24 hours, and the drying conditions may be, for example, a drying temperature of 100 to 250°C and a drying time of 3 to 24 hours.

[0046] The dehydrogenation catalyst of this embodiment carries a supported metal containing Pt. The supported metal may be supported on the support as an oxide or as an elemental metal.

[0047] The support may also support a metal element other than Pt. Examples of the other metal element include the above-mentioned Group 14 metal elements and metal elements similar to the examples of other metal elements that the support may contain. The other metal element may be supported on the support as a simple metal, as an oxide, or as a composite oxide with Pt.

[0048] The amount of Pt supported on the carrier is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the carrier. The amount of Pt supported on the carrier may be 5 parts by mass or less, or even 3 parts by mass or less, per 100 parts by mass of the carrier. With such a Pt amount, the Pt particles formed on the catalyst have a size suitable for the dehydrogenation reaction, and the platinum surface area per unit platinum weight is increased, resulting in a more efficient reaction system. Furthermore, with such a Pt amount, high activity can be maintained for a longer period of time while reducing catalyst costs.

[0049] The method for supporting a metal on a carrier is not particularly limited, and examples thereof include impregnation, deposition, coprecipitation, kneading, ion exchange, and pore filling.

[0050] One embodiment of a method for supporting a metal on a support is described below. First, the support is added to a solution in which a precursor of the target metal (supported metal) is dissolved in a solvent (e.g., alcohol, water, etc.), and the solution is stirred. Thereafter, the solvent is removed under reduced pressure, and the resulting solid is dried. The target metal can be supported on the support by calcining the dried solid.

[0051] In the above-mentioned supporting method, the precursor of the support metal may be, for example, a salt or complex containing a metal element. The salt containing a metal element may be, for example, an inorganic salt, an organic acid salt, or a hydrate thereof. The inorganic salt may be, for example, a sulfate, a nitrate, a chloride, a phosphate, a carbonate, etc. The organic salt may be, for example, an acetate, an oxalate, etc. The complex containing a metal element may be, for example, an alkoxide complex, an ammine complex, etc.

[0052] The stirring conditions may be, for example, a stirring temperature of 0 to 60°C and a stirring time of 10 minutes to 24 hours, and the drying conditions may be, for example, a drying temperature of 100 to 250°C and a drying time of 3 to 24 hours.

[0053] The calcination can be carried out, for example, in an air atmosphere or an oxygen atmosphere. The calcination can be carried out in one stage, or in two or more stages. The calcination temperature may be any temperature at which the precursor of the support metal can be decomposed, and may be, for example, 200 to 1000°C, or 400 to 800°C. When calcination is carried out in multiple stages, it is sufficient that at least one stage is at the above-mentioned calcination temperature. The calcination temperatures in the other stages may be, for example, in the same range as above, and may be 100 to 200°C.

[0054] The Pt dispersion in the dehydrogenation catalyst of this embodiment may be 10% or more, preferably 15% or more. A dehydrogenation catalyst having such a Pt dispersion tends to further suppress side reactions and maintain high activity for a longer period of time. The Pt dispersion is measured by a metal dispersion measurement method using CO as the adsorbed species, using the following apparatus and measurement conditions. Equipment: Metal dispersion measuring device R-6011 manufactured by Okura Riken Co., Ltd. Gas flow rate: 30 mL / min (helium, hydrogen) Sample weight: Approximately 0.1g (precisely weighed to four decimal places) Pretreatment: The sample is heated to 400°C under a hydrogen stream over 1 hour, and then reduced at 400°C for 60 minutes. The gas is then switched from hydrogen to helium, and the sample is purged at 400°C for 30 minutes. The sample is then cooled to room temperature under a helium stream. After allowing the detector to stabilize at room temperature, a CO pulse is performed. Measurement conditions: Under normal pressure helium gas flow, at room temperature (27°C), carbon monoxide 0.0929 cm 3 Pulse injection is performed one at a time and the amount of adsorption is measured. The number of adsorptions is repeated until the adsorption is saturated (minimum 3 times, maximum 15 times). The degree of dispersion is calculated from the measured amount of adsorption.

[0055] The dehydrogenation catalyst may be used in combination with a dehydrogenation catalyst other than those mentioned above. For example, a suitable example of the dehydrogenation catalyst other than those mentioned above is a catalyst using Cr as the supported metal in the above embodiment.

[0056] The dehydrogenation catalyst may be molded by extrusion molding, tablet molding or the like.

[0057] The dehydrogenation catalyst may contain a molding aid to improve moldability in the molding step, within a range that does not impair the physical properties or catalytic performance of the catalyst. The molding aid may be, for example, at least one selected from the group consisting of thickeners, surfactants, water retention agents, plasticizers, binder materials, etc. The molding step for molding the dehydrogenation catalyst may be performed at an appropriate stage in the production process of the dehydrogenation catalyst, taking into account the reactivity of the molding aid.

[0058] The shape of the molded dehydrogenation catalyst is not particularly limited and can be appropriately selected depending on the form in which the catalyst is used. For example, the shape of the dehydrogenation catalyst may be pellet-like, granular, honeycomb-like, sponge-like, or the like.

[0059] The dehydrogenation catalyst may be subjected to a reduction treatment as a pretreatment. The reduction treatment may be carried out, for example, by holding the dehydrogenation catalyst at 40 to 600°C under a reducing gas atmosphere. The holding time may be, for example, 0.05 to 24 hours. The reducing gas may be, for example, hydrogen, carbon monoxide, etc.

[0060] The use of a reduced dehydrogenation catalyst can shorten the initial induction period of the dehydrogenation reaction, which refers to a state in which the active metal contained in the catalyst has hardly been reduced and the activity of the catalyst is low.

[0061] The dehydrogenation step may be carried out, for example, by passing the raw material components through a reactor filled with a dehydrogenation catalyst. Various reactors used in gas-phase reactions using solid catalysts can be used as the reactor. Examples of the reactor include a fixed-bed reactor, a radial flow reactor, and a tubular reactor.

[0062] The dehydrogenation reaction may be carried out in a fixed bed, moving bed, or fluidized bed system, of which the fixed bed system is preferred from the viewpoint of facility costs.

[0063] The reaction temperature of the dehydrogenation reaction, i.e., the temperature inside the reactor, may be 300 to 800°C, 400 to 700°C, or 500 to 650°C, from the viewpoint of reaction efficiency. If the reaction temperature is 300°C or higher, the amount of cyclopentadiene produced tends to be greater. If the reaction temperature is 800°C or lower, the coking rate does not become too high, and the high activity of the dehydrogenation catalyst tends to be maintained for a longer period of time.

[0064] The reaction pressure, i.e., the atmospheric pressure inside the reactor, may be 0.01 to 1.1 MPa-A, 0.05 to 0.9 MPa-A, or 0.05 to 0.5 MPa-A. When the reaction pressure is within the above range, the dehydrogenation reaction tends to proceed more easily, and even better reaction efficiency tends to be obtained.

[0065] When the dehydrogenation step is carried out in a continuous reaction mode in which the raw material components are continuously supplied, the weight hourly space velocity (hereinafter referred to as "WHSV") is, for example, 0.1 h -1 It may be more than 0.5h -1 WHSV may be 20h or more. -1 May be less than 10 hours -1 Here, WHSV is the ratio (F / W) of the feed rate (feed mass / time) F of the raw material gas to the mass W of the dehydrogenation catalyst. -1 If the WHSV is 20h or more, the reactor size can be made smaller. -1 When the WHSV is not more than 1000 ppm, the yield of cyclopentadiene can be further increased. The amounts of the raw material gas and the catalyst used may be appropriately selected within more preferable ranges depending on the reaction conditions, the activity of the catalyst, etc., and the WHSV is not limited to the above range.

[0066] The dehydrogenation step is preferably carried out in an atmosphere containing hydrogen, which can further suppress deterioration of the dehydrogenation catalyst and enable cyclopentadiene to be produced efficiently with a higher yield.

[0067] When the dehydrogenation step is carried out in an atmosphere containing hydrogen, the hydrogen concentration in the atmosphere is preferably 5 to 95 mol %, more preferably 20 to 85 mol %. By setting the hydrogen concentration within the above range, the effect of suppressing deterioration of the dehydrogenation catalyst can be further improved, and the yield of cyclopentadiene can be further improved.

[0068] The dehydrogenation reaction results in a reaction mixture containing cyclopentadiene. In this embodiment, cyclopentadiene may be separated from the reaction mixture by a method such as distillation.

[0069] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. [Example]

[0070] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0071] The conditions and results of each Example and Comparative Example are shown in Tables 1 to 6. Graphs showing the yields of the main components contained in the reaction products obtained in each Example and Comparative Example are shown in Figures 1 to 7. In Figures 1 to 7, only the yield of cyclopentadiene is shown as a numerical value. The legends in each figure are as follows: C1: Methane C2-C4: Hydrocarbons with 2 to 4 carbon atoms i-C5: i-pentane i-C5 = i-pentene n-C5 = n-pentene n-C5==: n-Pentadiene cyC5: Cyclopentane cyC5=: Cyclopentene CPD: Cyclopentadiene aromatics: aromatic compounds

[0072] Example 1 <Preparation of Catalyst A-1> As a support precursor, 6.0 g of γ-alumina (Neobead GB-13, Mizusawa Industrial Chemicals, Ltd.; pH of 7.9 when suspended in water at a concentration of 1% by mass) with a particle size of 0.5–1 mm was prepared. The support precursor was mixed with a solution of 15.1 g of Mg(NO3)2·6H2O dissolved in 45 mL of water. The resulting mixture was stirred in a rotary evaporator at 40°C and 0.015 MPa for 30 minutes, then at 40°C and atmospheric pressure for an additional 30 minutes. The water was then removed under reduced pressure while stirring. The resulting solid was dried overnight in an oven at 130°C. The dried solid was then calcined in two stages in an air stream at 550°C for 3 hours and then at 800°C for 3 hours to obtain MgAl2O4-containing support A-1.

[0073] 10.0 g of carrier A-1 was impregnated with platinum using a nitric acid solution of dinitrodiammine platinum(II) (Tanaka Kikinzoku Kogyo, [Pt(NH3)2(NO2)2] / HNO3) to achieve a platinum loading of approximately 1 mass%, dried overnight at 130°C, and calcined at 550°C for 3 hours. This yielded catalyst A-1, in which Pt was supported on MgAl2O4. Analysis of the resulting catalyst A-1 by ICP spectroscopy revealed that the Pt loading, based on the total catalyst weight, was 1 mass%.

[0074] <Production of cyclopentadiene> n-Pentane (Fujifilm Wako Pure Chemical Industries, Ltd., special grade) was reacted in a fixed-bed flow reactor at 500°C under atmospheric pressure and a hydrogen-containing atmosphere (n-pentane:He:H2 = 1:9:3 (molar ratio), hydrogen concentration 23.1 mol%) for 1.1 h. -1 The reaction was carried out under the following conditions. Catalyst A-1 was used as the catalyst. The reaction product 90 minutes after the start of the reaction was analyzed using a gas chromatograph equipped with an FID detector to determine the yield of cyclopentadiene (CPD). The yields of the main components contained in the reaction product are also shown in the graph.

[0075] (Comparative Example 1) <Preparation of Catalyst B-1> 6.0 g of γ-alumina classified to a particle size of 0.5 to 1 mm (Neobead GB-13, manufactured by Mizusawa Industrial Chemicals, Ltd.; pH of a suspension of 1 mass% in water: 7.9) was prepared. This was dried to obtain a carrier B-1 containing Al2O3. Catalyst B-1 (Pt loading: 1 mass%) in which Pt was supported on Al2O3 was obtained in the same manner as in Example 1, except that this carrier B-1 was used.

[0076] <Production of cyclopentadiene> Cyclopentadiene was produced in the same manner as in Example 1 except that Catalyst B-1 was used, and the yield was determined.

[0077] (Comparative Example 2) <Preparation of Catalyst B-2> As the carrier B-2, CAriACT Q-15 manufactured by Fuji Silysia Chemical Ltd. was prepared. A catalyst B-2 (Pt loading: 1% by mass) in which Pt was supported on SiO was obtained in the same manner as in Example 1, except that this carrier B-2 was used.

[0078] <Production of cyclopentadiene> Cyclopentadiene was produced in the same manner as in Example 1 except that Catalyst B-2 was used, and the yield was determined.

[0079] (Comparative Example 3) <Preparation of Catalyst B-3> As the support B-3, the Catalysis Society reference catalyst JRC-CEO-3 was prepared. A catalyst B-3 (Pt loading: 1 mass%) in which Pt was supported on CeO was obtained in the same manner as in Example 1, except that this support B-3 was used.

[0080] <Production of cyclopentadiene> Cyclopentadiene was produced in the same manner as in Example 1 except that Catalyst B-3 was used, and the yield was determined.

[0081] Comparative Example 4 <Preparation of Catalyst B-4> As the carrier B-4, HSZ-890HOA manufactured by Tosoh Corporation was prepared. A catalyst B-4 (Pt loading: 1% by mass) in which Pt was supported on H-ZSM-5 was obtained in the same manner as in Example 1, except that this carrier B-4 was used.

[0082] <Production of cyclopentadiene> Cyclopentadiene was produced in the same manner as in Example 1 except that Catalyst B-4 was used, and the yield was determined.

[0083] Example 2 Cyclopentadiene was produced in the same manner as in Example 1 except that the reaction temperature during the production of cyclopentadiene was set to 550°C, and the yield was determined.

[0084] (Comparative Example 5) <Preparation of Catalyst B-5> 2.38 g of zinc nitrate hexahydrate (Kanto Chemical Co., Ltd., special grade), 6.0 g of aluminum nitrate nonahydrate (Kanto Chemical Co., Ltd., special grade), and 4.8 g of urea (Fujifilm Wako Pure Chemical Corporation, special grade) were added to 80 ml of ion-exchanged water and treated in an autoclave at 160 °C for 48 hours. After filtering and washing, the mixture was calcined at 600 °C for 4 hours to obtain ZnAl2O4-containing carrier B-5.

[0085] A catalyst B-5 (Pt loading: 1 mass %) in which Pt was loaded on ZnAl2O4 was obtained in the same manner as in Example 1, except that this carrier B-5 was used.

[0086] <Production of cyclopentadiene> Cyclopentadiene was produced in the same manner as in Example 2 except that Catalyst B-5 was used, and the yield was determined.

[0087] Examples 3 to 8 <Preparation of Catalysts A-2 to A-7> Catalysts A-2 to A-7, in which Pt was supported on MgAl2O4, were obtained in the same manner as in Example 1, except that the amount of Pt supported was changed to 0.1 mass% (A-2), 0.3 mass% (A-3), 0.5 mass% (A-4), 2.0 mass% (A-5), 3.0 mass% (A-6), or 5.0 mass% (A-7).

[0088] <Production of cyclopentadiene> Cyclopentadiene was produced and the yield was determined in the same manner as in Example 2, except that catalysts A-2 to A-7 were used.

[0089] Examples 9 to 12 Cyclopentadiene was produced and the yield was determined in the same manner as in Example 2, except that the molar ratio of n-pentane:He:H in the atmosphere during cyclopentadiene production was changed to 1:11:1 (hydrogen concentration 7.7 mol%, Example 9), 1:7:5 (hydrogen concentration 38.5 mol%, Example 10), 1:5:7 (hydrogen concentration 53.8 mol%, Example 11), or 1:4:8 (hydrogen concentration 61.5 mol%, Example 12).

[0090] (Examples 13 to 17) Cyclopentadiene was produced in the same manner as in Example 9, Example 2, Example 10, Example 11, or Example 12, and the reaction product 390 minutes after the start of the reaction was analyzed to determine the yield of cyclopentadiene.

[0091] (Examples 18 to 22) When producing cyclopentadiene, the raw material component was changed to n-pentane (Example 18), cyclopentane (Example 19), cyclopentene (Example 20), 1-pentene (Example 21), or 2-pentene (Example 22), and cyclopentadiene was produced in the same manner as in Example 1. The reaction product 160 minutes after the start of the reaction was analyzed to determine the yield of cyclopentadiene.

[0092] (Examples 23 to 27) <Preparation of Catalysts A-8 to A-12> 10.0 g of catalyst A-1 was impregnated with sodium stannate (Na2SnO3, Showa Kako Co., Ltd.) to achieve a tin-to-platinum molar ratio (Sn / Pt) of 0.1 (A-8), 0.2 (A-9), 0.5 (A-10), 0.7 (A-11), or 1.0 (A-12). The catalysts were then dried overnight at 130°C and calcined at 550°C for 3 hours. These catalysts were then washed with pure water until the conductivity of the washings reached 80 μS / cm or less, after which they were dried overnight at 130°C. This yielded catalysts A-8 to A-12, in which Pt and Sn were supported on MgAl2O4.

[0093] <Production of cyclopentadiene> Cyclopentadiene was produced and the yield was determined in the same manner as in Example 2 except that catalysts A-8 to A-12 were used.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] [Table 4]

[0098] [Table 5]

[0099] [Table 6]

[0100] As is clear from the results shown in Tables 1 to 6, it was confirmed that the production methods of the Examples can produce cyclopentadiene in a higher yield than the production methods of the Comparative Examples when the reaction is carried out for a long period of time (90 minutes or more). Furthermore, from the above results, it was confirmed that the production methods of the Examples do not deactivate the catalyst in the first few minutes of the reaction, and that catalyst deterioration can be suppressed.

Claims

1. a dehydrogenation step of contacting a raw material component containing at least one selected from the group consisting of a normal hydrocarbon having 5 carbon atoms, cyclopentane, and cyclopentene with a dehydrogenation catalyst to obtain cyclopentadiene, the dehydrogenation catalyst comprises a metal oxide support containing Al and a Group 2 metal element, and a supported metal containing Pt supported on the support, the Group 2 metal element includes Mg, A method for producing cyclopentadiene, wherein the metal oxide support contains MgAl 2 O 4 , which is a composite oxide of Al and Mg, as the composite oxide of Al and the Group 2 metal element.

2. 2. The method for producing cyclopentadiene according to claim 1, wherein the content of the Group 14 metal element in the dehydrogenation catalyst is 1.0 mass% or less based on the total amount of the dehydrogenation catalyst.

3. 3. The method for producing cyclopentadiene according to claim 1, wherein in the dehydrogenation catalyst, a molar ratio of the Group 14 metal element to the Pt (number of moles of Group 14 metal element / number of moles of Pt) is 1.0 or less.

4. The method for producing cyclopentadiene according to any one of claims 1 to 3, wherein the content of the Pt in the dehydrogenation catalyst is 0.1 to 10 mass% based on the total amount of the dehydrogenation catalyst.

5. The method for producing cyclopentadiene according to any one of claims 1 to 4, wherein the dehydrogenation step is carried out in an atmosphere containing hydrogen.

6. A method for producing cyclopentadiene described in any one of claims 1 to 5, wherein the molar ratio of the Group 2 metal element to Al in the dehydrogenation catalyst (number of moles of Group 2 metal element / number of moles of Al) is 0.30 or more and 0.60 or less.

7. The method for producing cyclopentadiene according to claim 1, wherein the content of Al in the metal oxide support is 20 mass% or more based on the total mass of the metal oxide support.

8. A method for producing cyclopentadiene described in any one of claims 1 to 7, wherein the content of the composite oxide of Al and the Group 2 metal element in the metal oxide support is 60 mass% or more based on the total mass of the metal oxide support.

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