Method for producing cyclopentadiene

Abstract

To provide, as a new cyclopentadiene production method, a method for producing cyclopentadiene stably over a long period of time at a high yield by using a zeolite catalyst in the presence of an olefin.SOLUTION: A method for producing cyclopentadiene comprises a ring-forming dehydrogenation step for bringing a material composition containing an olefin having 5 carbon atoms into contact with a zeolite catalyst having an MFI structure to give a reaction product containing cyclopentadiene, where the zeolite catalyst has Lewis acidity and strong solid basicity and includes, in the zeolite backbone, at least one metal atom selected from transition metals or post-transition metals.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Various uses of hydrocarbons with a carbon number of 5 have been proposed in the past. For example, cyclopentadiene is widely used industrially as a raw material for the synthesis of agricultural chemicals, insecticides, and various resin plasticizers. Cyclopentadiene can be obtained, for example, by recovering cyclopentadiene from a C5 fraction, which is mainly composed of hydrocarbons with a carbon number of 5 and is a by-product of the production of ethylene by liquid feed steam cracking (e.g., naphtha and heavier feedstocks), through a dimerization process and a distillation process. However, the content of cyclopentadiene contained in the C5 fraction is low, and existing liquid feed steam cracking apparatuses are shifting to lighter feedstocks than naphtha, so it is expected that the supply amount will not be sufficient to meet the demand for cyclopentadiene. Therefore, a method for producing cyclopentadiene that is not restricted by the supply limit of existing production methods is being considered.

[0003] For example, Non-Patent Document 1 describes a method for producing cyclopentadiene from n-pentane, n-pentene, and 1,3-pentadiene using a Pt / SiO2 catalyst. The yields to cyclopentadiene are as high as 21%, 35%, and 53% for the conversion of n-pentane, n-pentene, and 1,3-pentadiene at 600°C, respectively, indicating that olefins are predominant in the conversion to cyclopentadiene. [Prior art documents] [Non-patent literature]

[0004] [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]

[0005] However, in the method described in Non-Patent Document 1, it is reported in the document that the catalyst deteriorates in a short time (for example, within 15 minutes). This is thought to be because when olefins are dehydrogenated, coke is likely to be generated during the reaction, and the generated coke accumulates on the catalyst surface, deactivating the catalyst. For this reason, in conventional cyclopentadiene production methods, there has been insufficient research into stably producing cyclopentadiene at a high yield over a long period of time in the coexistence of olefins, and there is still room for improvement.

[0006] An object of the present invention is to provide a novel process for producing cyclopentadiene, which is capable of stably producing cyclopentadiene in high yield over a long period of time using a zeolite catalyst in the coexistence of an olefin. [Means for solving the problem]

[0007] Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result have found that by using a specific zeolite catalyst, cyclopentadiene can be produced stably over a long period of time in a high yield from a raw material composition containing an olefin having a carbon number of 5, and have completed the present invention.

[0008] One aspect of the present invention relates to a method for producing cyclopentadiene, comprising a cyclization dehydrogenation step of contacting a raw material composition containing an olefin having a carbon number of 5 with a zeolite catalyst having an MFI structure to obtain a reaction product containing cyclopentadiene. In this production method, the zeolite catalyst contains at least one metal atom selected from transition metals and post-transition metals in the zeolite framework, and has Lewis acidity and strong solid basicity.

[0009] In one embodiment, the feed composition may contain a diolefin having 5 carbon atoms.

[0010] In one embodiment, the content of the diolefin having 5 carbon atoms in the raw material composition may be 5% by mass or more.

[0011] In one embodiment, the metal atom is one or more selected from Zn atoms, Fe atoms, and Ni atoms, and the content of the metal atom may be 1 to 15 atom % relative to the Si atom.

[0012] In one embodiment, the zeolite catalyst may contain no alkali metal or may contain 1 atom % or less of alkali metal relative to the Si atoms of the zeolite framework.

[0013] In one embodiment, the zeolite catalyst may be one in which Pt is supported.

[0014] In one embodiment, in the cyclization dehydrogenation step, the gas flow rate (ml / min) ratio between the raw material composition and molecular hydrogen supplied to the reaction system may be 1:0.001 to 1:3. Effect of the Invention

[0015] According to the present invention, there is provided a novel process for producing cyclopentadiene, which is capable of stably producing cyclopentadiene in high yield over a long period of time using a zeolite catalyst in the coexistence of an olefin. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 shows the results of synchrotron XRD analysis of the zeolite catalyst and the Zn-impregnated supported catalyst according to the examples. [Diagram 2] FIG. 2 is a diagram showing the results of 29Si MAS NMR measurement of a zeolite catalyst according to an example. [Diagram 3] FIG. 2 is a diagram showing the results of FT-IR analysis of a zeolite catalyst, a ZnO crystal, and a Zn-impregnated supported catalyst according to an embodiment. [Figure 4]FIG. 1 is a diagram showing the results of FT-IR analysis of the zeolite catalyst, ZnO crystals, and Zn-impregnated supported catalyst according to the examples, with pyridine adsorbed thereon. [Diagram 5] FIG. 2 is a diagram showing the results of CO2-TPD analysis of the zeolite catalyst and the Zn-impregnated supported catalyst according to the embodiment. [Figure 6] FIG. 2 is a diagram showing the results of NH3-TPD analysis of the zeolite catalyst and the Zn-impregnated supported catalyst according to the examples. [Figure 7] FIG. 2 is a diagram showing the results of UV-vis analysis of the zeolite catalyst and ZnO crystals according to the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The manufacturing method of the present invention will be described in detail below, but the explanation of the constituent elements described below is an example (representative example) of one embodiment of the present invention, and the present invention is not limited to these contents.

[0018] The method for producing cyclopentadiene according to this embodiment includes a cyclization / dehydrogenation step of contacting a raw material composition containing an olefin having a carbon number of 5 with a zeolite catalyst having an MFI structure to obtain a reaction product containing cyclopentadiene. According to the production method of this embodiment, by using a specific zeolite catalyst, cyclopentadiene can be produced stably over a long period of time with a high yield.

[0019] (Zeolite catalyst) The zeolite catalyst according to this embodiment contains at least one metal atom selected from transition metals or post-transition metals in the zeolite framework, and has Lewis acidity and strong solid basicity.

[0020] In the zeolite catalyst according to the present embodiment, there is almost no Bronsted acid in the zeolite catalyst, and only Lewis acid is present. It is generally known that the amount of by-products produced in the cyclization dehydrogenation reaction increases or decreases depending on the presence of Bronsted acid. However, since there is almost no Bronsted acid in the zeolite catalyst according to the present embodiment, it is possible to control the side reaction and suppress the generation of by-products. By using the zeolite catalyst according to the present embodiment for the production of cyclopentadiene, for example, it is considered that the side reaction is suppressed and the cyclopentadiene selectivity is improved, and the generation of coke due to the polymerization of cracking by-products is suppressed, and thus cyclopentadiene can be stably produced for a long period of time. Furthermore, since the zeolite catalyst according to the present embodiment has Lewis acid sites that can be active sites for the cyclization dehydrogenation reaction highly dispersed, the use of the zeolite catalyst according to the present embodiment for the production of cyclopentadiene allows cyclopentadiene to be produced in a high yield.

[0021] Here, zeolite refers to a crystalline substance in which TO4 units (T is the central atom) having a tetrahedral structure are three-dimensionally linked by sharing O atoms to form regular micropores.

[0022] The transition metal refers to a metal that belongs to Groups 3 to 12 of the long-period periodic table of elements based on the provisions of the International Union of Pure and Applied Chemistry (IUPAC). Post-transition metals refer to base metals with atomic numbers later than the transition metals in periods 4, 5, and 6 of the periodic table.

[0023] The inclusion of metal atoms in the zeolite framework means that metal atoms are introduced into the zeolite framework in the same manner as silicon (Si) by, for example, mixing a compound containing the target metal atom as a raw material for hydrothermal synthesis. The state in which metal atoms are included in the zeolite framework can be understood by various measurement methods such as, for example, XRD (X-ray Diffraction), NMR (Nuclear Magnetic Resonance spectroscopy), FT-IR (Fourier Transform Infrared Spectroscopy), XPS (X-ray Photoelectron Spectroscopy), and ESCA (Electron Spectroscopy for Chemical Analysis).

[0024] Lewis acidity refers to the ability to accept unshared electron pairs. For example, when pyridine is adsorbed on a zeolite catalyst and analyzed by FT-IR, the Lewis acidity is -1 This means that an absorption band is detected in the vicinity.

[0025] "Solid basicity" means that the surface of the zeolite catalyst is basic. "Strong solid basicity" means that the surface of the zeolite catalyst is strongly basic, and for example, when a CO2-TPD analysis is performed using a TPD (Temperature Programmed Desorption) analyzer, a desorption peak of CO2 adsorbed on the zeolite catalyst is detected in the high temperature range of 500°C or higher.

[0026] The zeolite catalyst according to the present embodiment is a zeolite with a 10-membered ring structure and has an MFI structure. The zeolite with the MFI structure is not particularly limited, but is preferably a crystalline metallosilicate. The zeolite with the MFI structure means a zeolite that corresponds to MFI in the structure code databased by the International Zeolite Association. Whether a zeolite has a 10-membered ring structure, particularly an MFI structure, can be confirmed by, for example, X-ray diffraction.

[0027] The metal atoms contained in the zeolite framework are not particularly limited as long as they are transition metal atoms or post-transition metal atoms, and for example, titanium (Ti), vanadium (V), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), zirconium (Zr), indium (In), etc. can be used. Among these, zinc (Zn), nickel (Ni), and iron (Fe) are preferred from the viewpoint of excellent reactivity in the cyclization dehydrogenation reaction. The metal atoms contained in the zeolite framework may be of one type alone or two or more types.

[0028] The content of metal atoms contained in the zeolite skeleton is not particularly limited, but is preferably 1 to 15 atom%, more preferably 1 to 10 atom%, and even more preferably 1 to 3 atom% relative to silicon (Si) atoms. If the content of metal atoms contained in the zeolite skeleton is equal to or greater than the lower limit of the above range, the zeolite catalyst has more solid base sites, and tends to have excellent reactivity in the cyclization dehydrogenation reaction. If the content of metal atoms contained in the zeolite skeleton is equal to or less than the upper limit of the above range, the reaction efficiency of the cyclization dehydrogenation reaction of the raw material relative to the metal content tends to be excellent.

[0029] The content of alkali metal contained in the zeolite catalyst is preferably 1 atom% or less, more preferably 0.1 atom% or less, based on Si atoms, and is less than the upper limit. If it is less than the upper limit, it tends to be possible to maintain high reactivity of the cyclization dehydrogenation reaction while maintaining promotion of zeolite crystallization.

[0030] From the viewpoint of improving moldability, the zeolite catalyst may further contain a molding aid within the scope of the present invention. The molding aid may be, for example, at least one selected from the group consisting of a thickener, a surfactant, a water retention agent, a plasticizer, a binder raw material, etc. The molding step of molding the zeolite catalyst may be performed at an appropriate stage in the manufacturing process of the zeolite catalyst, taking into consideration the reactivity of the molding aid.

[0031] The zeolite catalyst may be one in which platinum is supported on a carrier using a platinum (Pt) source. Examples of the platinum source include tetraammineplatinic (II) acid, tetraammineplatinic (II) acid salts (e.g., nitrates, etc.), tetraammineplatinic (II) acid hydroxide solution, dinitrodiammineplatinic (II) nitric acid solution, hexahydroxoplatinic (IV) acid nitric acid solution, and hexahydroxoplatinic (IV) acid ethanolamine solution. It is preferable to use a metal source that does not contain chlorine atoms as the platinum source. By using a metal source that does not contain chlorine atoms, corrosion of the device can be suppressed, and the cyclization dehydrogenation reaction can be carried out more efficiently.

[0032] When platinum is supported on the zeolite catalyst, the platinum content in the zeolite-supported platinum catalyst is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on the total amount of the zeolite-supported platinum catalyst. The platinum content is preferably 3.0% by mass or less, more preferably 2.5% by mass or less, based on the total amount of the zeolite-supported platinum catalyst. When the platinum content in the zeolite-supported platinum catalyst is within the above range, the platinum surface area per unit platinum weight is large, which tends to realize a more efficient reaction system.

[0033] The zeolite catalyst may be used after reduction treatment as a pretreatment. The reduction treatment may be performed, for example, by holding the zeolite 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 contain, for example, hydrogen, carbon monoxide, etc. By using a zeolite catalyst that has been reduced, the initial induction period of the cyclization dehydrogenation reaction can be shortened. The initial induction period of the cyclization dehydrogenation reaction refers to a state in which very few of the supported metals in the zeolite catalyst are reduced to an active state, and the activity of the catalyst is low.

[0034] <Method for preparing zeolite catalyst> The zeolite catalyst according to the present embodiment can be prepared by combining a silica gel aging step, a hydrothermal synthesis step, and a calcination step, thereby making it possible to prepare the zeolite catalyst without using an alkali metal, boron, or aluminum.

[0035] An example of a suitable preparation example of the zeolite catalyst according to this embodiment includes mixing a silica source, an organic structure directing agent (OSDA), and water, aging (stirring) at 100°C or less for 10 hours or more, and then mixing a transition metal atom or a post-transition metal atom as a metal source, followed by hydrothermal synthesis at 100°C or more, and then calcining at 500°C or more for 5 hours or more. When platinum is supported on the zeolite catalyst, the method for supporting platinum is not particularly limited, and for example, an impregnation method, a deposition method, a coprecipitation method, a kneading method, an ion exchange method, a pore filling method, etc. can be used.

[0036] As the silica source, for example, silicon alcoholates, silanes, silicon tetrachloride, water glass, and other hydrolyzable silicon compounds can be used. The organic structure-directing agent is not particularly limited as long as it can obtain a zeolite having an MFI structure, and for example, a quaternary alkyl ammonium salt, an amine, etc. The organic structure-directing agent may be used alone or in combination of two or more kinds.

[0037] As an example of a suitable preparation example of the zeolite catalyst according to the present embodiment, it is preferable to further include a step of washing the synthesized product with water before calcining the synthesized product obtained after the hydrothermal synthesis. By including the water washing step, the effect of alkali such as sodium on the zeolite catalyst can be reduced.

[0038] The above method is an example of a suitable preparation example for preparing a zeolite catalyst without using an alkali metal, boron, or aluminum, but the preparation method of this embodiment does not limit the use of an alkali metal, boron, or aluminum as long as it does not deviate from the spirit of the present invention. For example, an alkali metal may be mixed during hydrothermal synthesis as long as it does not deviate from the spirit of the present invention. By mixing an alkali metal, the promotion of crystallization of the zeolite is maintained, and it tends to be easy to obtain a zeolite catalyst with an MFI structure in which a transition metal atom or a post-transition metal atom is introduced into the zeolite framework. Examples of the alkali metal include sodium (Na), potassium (K), and rubidium (Rb). Among these, sodium (Na) is preferred. As described above, the amount of the alkali metal to be mixed is preferably 1 atom% or less relative to the Si atoms in the zeolite catalyst.

[0039] The above-described method can provide a zeolite catalyst in which transition metal atoms or post-transition metal atoms are introduced into the zeolite framework and active sites are highly dispersed, and can also provide a zeolite catalyst having strong solid basicity in which there is almost no Bronsted acid and only Lewis acid.

[0040] (Production method of cyclopentadiene) In the production method according to the present embodiment, in the cyclization dehydrogenation step, a raw material composition containing an olefin having a carbon number of 5 is contacted with the above-mentioned zeolite catalyst, whereby a cyclization dehydrogenation reaction of the olefin having a carbon number of 5 occurs, and a reaction product containing cyclopentadiene is obtained.

[0041] <Raw material composition> The raw material composition may contain an olefin having at least 5 carbon atoms. The olefin having 5 carbon atoms is an organic compound having one or more carbon-carbon double bonds in the molecule, usually having no functional groups, and means a linear and / or branched hydrocarbon having 5 carbon atoms. The olefin having 5 carbon atoms according to this embodiment is preferably a monoolefin and / or diolefin having 5 carbon atoms.

[0042] A monoolefin having 5 carbon atoms is an organic compound having only one carbon-carbon double bond in the molecule and usually having no functional groups, and refers to a linear and / or branched hydrocarbon having 5 carbon atoms. Examples of the monoolefin having 5 carbon atoms according to the present embodiment include 1-pentene, 2-pentene, 2-methyl-1-butene, 2-methyl-2-butene, and 3-methyl-1-butene, and among these, it is preferable to use 1-pentene. The monoolefin having 5 carbon atoms may be one of the above alone or a mixture containing two or more of them.

[0043] A diolefin having 5 carbon atoms is an organic compound having two or more carbon-carbon double bonds in the molecule and usually having no functional groups, and refers to a linear and / or branched hydrocarbon having 5 carbon atoms. Examples of the diolefin having 5 carbon atoms according to the present embodiment include 1,3-pentadiene and 1,4-pentadiene, and among these, it is preferable to use 1,3-pentadiene. The diolefin having 5 carbon atoms may be one of the above alone or a mixture containing two or more of them.

[0044] The raw material composition may further contain compounds other than olefins having a carbon number of 5, within the scope of the present invention. For example, the raw material composition may contain a C5 fraction mainly composed of hydrocarbons having a carbon number of 5 obtained in a naphtha pyrolysis furnace or the like. The raw material composition may be used as it is in a state in which compounds other than olefins having a carbon number of 5 are arbitrarily mixed due to the production method, or may be used after purification. The content of the olefin having 5 carbon atoms in the raw material composition is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

[0045] The content of the monoolefin having 5 carbon atoms in the raw material composition is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 40% by mass or more, particularly preferably 50% by mass or more, and may be 100% by mass.

[0046] The content of the diolefin having 5 carbon atoms in the raw material composition is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more. The content is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably 75% by mass or less, and particularly preferably 70% by mass or less. When the diolefin content is equal to or greater than the lower limit, the yield of cyclopentadiene tends to be high. When the diolefin content is equal to or less than the upper limit, coke formation in the cyclization dehydrogenation reaction tends to be efficiently suppressed.

[0047] The olefin having 5 carbon atoms may be a mixture of a monoolefin having 5 carbon atoms and a diolefin having 5 carbon atoms. The mixing ratio (mass ratio) of the monoolefin having 5 carbon atoms and the diolefin having 5 carbon atoms is not particularly limited and may depend on the ratio resulting from the production method. The mixing ratio (mass ratio) of the monoolefin having 5 carbon atoms and the diolefin having 5 carbon atoms is preferably 20:80 to 95:5, more preferably 25:75 to 90:10, and further preferably 30:70 to 85:15.

[0048] <Cyclization dehydrogenation process> In the cyclization dehydrogenation step, for example, a reactor filled with a zeolite catalyst may be used, and the raw material composition may be passed through the reactor to carry out the cyclization dehydrogenation reaction. As the reactor, various reactors used in gas phase reactions using solid catalysts may be used. As the reactor, for example, a fixed bed adiabatic reactor, a radial flow reactor, a tubular reactor, etc. may be mentioned.

[0049] The reaction type of the cyclization dehydrogenation reaction is a continuous reaction type in which the raw material composition is continuously supplied, and may be, for example, a fixed bed type, a moving bed type, or a fluidized bed type. Among these, the fixed bed type is preferred from the viewpoint of equipment costs.

[0050] The temperature when the raw material composition is contacted with the zeolite catalyst (which can also be referred to as the reaction temperature of the cyclization dehydrogenation reaction or the temperature inside the reactor) is preferably 350 to 800°C, more preferably 400 to 700°C, and even more preferably 450 to 650°C, from the viewpoint of reaction efficiency. When the reaction temperature is equal to or higher than the above lower limit, the yield of cyclopentadiene tends to be further improved. When the reaction temperature is equal to or lower than the above upper limit, the rate of coke formation is suppressed, and the high cyclization dehydrogenation activity of the zeolite catalyst tends to be maintained for a longer period of time.

[0051] The pressure when the raw material composition is contacted with the zeolite catalyst (which can also be referred to as the reaction pressure of the cyclization dehydrogenation reaction or the pressure inside the reactor) is preferably 0.01 to 4.0 MPa, more preferably 0.03 to 0.5 MPa, and even more preferably 0.05 to 0.3 MPa. If the reaction pressure is within the above range, the cyclization dehydrogenation reaction tends to proceed easily, and even better reaction efficiency tends to be obtained.

[0052] The raw material composition to be supplied to the reaction system is preferably a gas. When the raw material composition is a gas, it can be mixed with a gas other than the raw material composition and supplied to the reaction system as a gas containing the raw material composition. The gas other than the raw material composition may be a gas that is substantially inert under the cyclization dehydrogenation reaction conditions. Examples of the gas that is substantially inert under the cyclization dehydrogenation reaction conditions include molecular hydrogen, nitrogen, argon, neon, carbon dioxide, helium, and steam. In addition to the gas other than the raw material composition, any diluent that is substantially inert under the cyclization dehydrogenation reaction conditions may be supplied to the reaction system.

[0053] When the cyclization dehydrogenation step is carried out in a continuous reaction format in which the raw materials are continuously supplied, the gas flow rate (ml / min) ratio between the raw material composition supplied to the reaction system and the gas substantially inert under the cyclization dehydrogenation reaction conditions is preferably 1:0.1 to 1:20, more preferably 1:0.5 to 1:10. In particular, when molecular hydrogen is used among the gases substantially inert under the cyclization dehydrogenation reaction conditions, the gas flow rate (ml / min) ratio between the raw material composition supplied to the reaction system and the molecular hydrogen is preferably 1:0.001 to 1:3, more preferably 1:0.001 to 1:0.5. In the dehydrogenation reaction using a solid acid catalyst, molecular hydrogen is usually supplied to the reaction system to suppress deactivation of the catalyst due to coke generation. However, in the production method of this embodiment, as shown in the examples described later, catalyst deactivation is hardly observed even if molecular hydrogen is not supplied to the reaction system. Therefore, in the production method of this embodiment, molecular hydrogen does not need to be substantially supplied to the reaction system. In this specification, "substantially not supplying molecular hydrogen to the reaction system" means that molecular hydrogen is not intentionally supplied to the reaction system, and for example, the gas flow rate (ml / min) ratio of the raw material composition and molecular hydrogen supplied to the reaction system is less than 1:0.001. This makes it possible to reduce the production cost of cyclopentadiene, which is industrially useful.

[0054] When the cyclization dehydrogenation step is carried out in a continuous reaction format in which the raw material is continuously supplied, the mass hourly space velocity (hereinafter sometimes referred to as "WHSV") is set to 0.01 h from the viewpoint of improving the conversion rate of the raw material. -1 More than 0.1h is preferable. -1 More preferably, the WHSV is 100 h or less from the viewpoint of reducing the reactor size. -1 Less than 20 hours is preferable. -1 The following is more preferred: Here, WHSV is the ratio (F / W) of the feed rate (feed amount / time) F of the raw material to the mass W of the zeolite catalyst in a continuous reaction apparatus. The amounts of the raw material composition and catalyst used may be appropriately selected within more preferable ranges depending on the reaction conditions, catalyst activity, etc., and WHSV is not limited to the above range.

[0055] The method for separating and purifying cyclopentadiene from the reaction product obtained by the cyclodehydrogenation step is not particularly limited, and it can be purified by known distillation operations or the like. In addition, unreacted raw materials may be recovered from the reaction product after separating cyclopentadiene, and the recovered raw materials may be mixed with new raw materials and reused.

[0056] As described above, according to the production method according to the present embodiment, by using a specific zeolite catalyst, cyclopentadiene can be stably produced from a raw material composition containing olefins having 5 carbon atoms at a high yield over a long period of time.

Examples

[0057] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.

[0058] [Catalyst Preparation Example 1] <Preparation of Pt / [Zn]-MFI Catalyst> (1) Aging step 20.0 g of tetraethyl orthosilicate (TEOS) and 20.3 g of a 25% by mass aqueous solution of tetrapropylammonium hydroxide (TPAOH, organic structure-directing agent) were added into a stainless steel pressure-resistant container, sealed, and stirred (aged) at 80 °C for 24 hours. The state of the mixture after stirring was liquid.

[0059] (2) Hydrothermal synthesis step 2.2 g of zinc nitrate hexahydrate was dissolved in 4.7 g of ion-exchanged water. Then, it was added to the mixture obtained in the aging step, and stirred until homogenized at room temperature (25 to 30 °C). The stirred mixture was put into an autoclave, and hydrothermal synthesis was carried out at 175 °C for 24 hours while rotating at 20 rpm.

[0060] (3) Calcination step The mixture after the hydrothermal synthesis step was put into a centrifuge tube, and a gel-like sample was obtained by centrifugation. Then, this gel-like sample was washed with ion-exchanged water. The gel sample was washed by adding ion-exchanged water and then centrifuging. The pH of the supernatant after centrifugation was measured, and washing and centrifugation were repeated until the pH was within the range of 7 to 8. The washed gel sample was dried overnight at 90°C. The dried sample was placed in a muffle furnace and calcined in an air environment at 550°C for 8 hours to remove organic matter (tetrapropylammonium ions (cations)) and obtain a zeolite catalyst ([Zn]-MFI catalyst).

[0061] The obtained zeolite catalyst was subjected to the following measurements. (a) Synchrotron XRD analysis XRD analysis was carried out using a synchrotron XRD instrument. (b) Solid-state NMR analysis NMR (JEOL Ltd., ECA-600) 29 Si MAS NMR measurements were carried out. (c)FT-IR analysis The structure was analyzed by FT-IR (FT / IR-4600, manufactured by JASCO Corporation) by evacuating the sample to a vacuum at 450° C. for 1 hour as a pretreatment. (d)CO2-TPD analysis CO2-TPD analysis was performed using a TPD analyzer (Microtrack Bell, BELCAT II). Approximately 30 mg of zeolite catalyst was pretreated at 500°C for 1 hour while flowing helium gas at a flow rate of 50 mL / min. After that, it was cooled to less than 40°C, and 1 vol% CO2 / He gas was flowed at a flow rate of 50 mL / min to adsorb CO2 to the zeolite catalyst, and then helium gas was flowed at a flow rate of 50 mL / min for 5 minutes. Then, while flowing helium gas at 30 mL / min, the temperature was raised to 800°C at a heating rate of 10°C / min, and the desorption of CO2 was analyzed by TCD (Thermal Conductivity Detector) and MASS. BELMass, manufactured by Microtrack Bell, was used for MASS. The amount of base was measured by calculation from the peak area measured by CO2-TPD. (e)NH3-TPD analysis NH3-TPD analysis was performed using a TPD analyzer (Microtrack Bell, BELCAT II). Approximately 30 mg of zeolite catalyst was pretreated at 500°C for 1 hour while flowing helium gas at a flow rate of 50 mL / min. After that, it was cooled to 100°C, and 1 vol% NH3 / He gas was flowed at a flow rate of 50 mL / min to adsorb NH3 on the zeolite catalyst, and helium gas was flowed at a flow rate of 50 mL / min for 15 minutes. Then, while flowing helium gas at 30 mL / min, the temperature was raised to 700°C at a heating rate of 10°C / min, and the desorption of NH3 was analyzed by TCD and MASS. For MASS, BELMass, Microtrack Bell, was used. The amount of Lewis acid was measured by calculation from the peak area measured by NH3-TPD. (f)UV-vis analysis UV-vis analysis was performed using an ultraviolet-visible near-infrared spectrophotometer (V-660, manufactured by JASCO Corporation). The measurement method was the diffuse reflectance method, and the analysis was performed at room temperature.

[0062] (a) Synchrotron XRD analysis The results of the synchrotron XRD analysis are shown in Figure 1. In the Zn / [Si]-MFI catalyst shown in Catalyst Preparation Example 2 described later, a peak due to ZnO crystals was observed at the position indicated by the dotted line, but in the [Zn]-MFI catalyst, no peak due to ZnO crystals was observed. (b) Solid-state NMR analysis 29 The results of the Si MAS NMR analysis are shown in Figure 2. Zeolite composed of Si, O, and Zn 29When measured by Si MAS NMR, if the four bonds of the Si atom are only -O-Si, a peak appears at -110 to -120 ppm, and if at least one of the four bonds of the Si atom is -O-Zn, a peak appears around -100 ppm ("Synthesis and Characterization of Zincosilicates with the SOD Topology" MACamblor, RF Lobe, H. Koller, MEDavis, Chemistry of Materials, 6, P. 2193-2199 (1994)). This -100 ppm peak was observed in the [Zn]-MFI catalyst. (c)FT-IR analysis Figure 3 shows the results of FT-IR analysis at room temperature after pretreatment by evacuation at 450°C for 1 hour. If Zn exists close to each other, it will become Zn-O-Zn after pretreatment. In ZnO crystals and Zn-impregnated supported catalysts, the FT-IR analysis shows a peak at 3600-3700 cm -1 However, in the [Zn]-MFI catalyst, there is an absorption band at 3640 cm due to the Zn-OH vibration of Zn. -1 Absorption bands in the vicinity are observed, suggesting that the Zn is incorporated into the zeolite framework and is isolated from other Zn atoms. In addition, after the pretreatment, the catalyst was cooled to 150°C, pyridine was introduced, and the temperature was raised to 250°C while evacuating to a vacuum, after which FT-IR analysis was performed. The results are shown in Figure 4. In the presence of a Brønsted acid, pyridine was adsorbed on the zeolite catalyst and measured by FT-IR, and a peak was observed at 1560 cm -1 It is known that an absorption band due to the vibration of C6H5N-H is observed around this region. However, this absorption band was not observed in the [Zn]-MFI catalyst. In the presence of Lewis acid, pyridine is adsorbed on a zeolite catalyst and measured by FT-IR, and the -1 It is known that an absorption band is observed around 1450 cm for the [Zn]-MFI catalyst. -1 From this, it was found that the [Zn]-MFI catalyst does not have a Brønsted acidity, but only a Lewis acidity. (d)CO2-TPD analysis The results of the CO2-TPD analysis are shown in Figure 5. In the CO2-TPD analysis, the zeolite catalyst containing general aluminum shows a peak in the low temperature range around 100°C, but no peak is seen in the high temperature range above 500°C. In addition, the Zn-impregnated supported catalyst shows a peak only around 100°C. However, the [Zn]-MFI catalyst shows a peak in the high temperature range above 500°C, confirming that the solid basicity of this zeolite catalyst is strong. The amount of solid base calculated from the peak area in the high temperature range above 500°C by CO2-TPD was 0.001 to 0.035 mmol / g. (e)NH3-TPD analysis The results of the NH3-TPD analysis are shown in Figure 6. In the NH3-TPD analysis, a broad peak was observed around 200°C for the Zn-impregnated supported catalyst. On the other hand, a large broad peak was observed from 150°C to 500°C for the [Zn]-MFI catalyst. In the FT-IR analysis, it was confirmed that the [Zn]-MFI catalyst does not have a Bronsted acid, but only a Lewis acid, so this peak is considered to be due to the release of NH3 adsorbed by the Lewis acid. In addition, the amount of acid calculated from the peak area was 0.01 to 0.2 mmol / g. (f)UV-vis analysis The results of the UV-vis analysis are shown in Figure 7. In the UV-vis analysis, the ZnO crystal peak is at 255-322 nm, and the ZnO clusters in the zeolite pores have a peak at 240 nm. No peaks of ZnO crystals or ZnO crystals in the zeolite pores were observed in the [Zn]-MFI catalyst, suggesting that Zn atoms are highly dispersed within the zeolite framework.

[0063] From the above results, it was confirmed that the obtained [Zn]-MFI catalyst is a zeolite catalyst with an MFI structure that has no Bronsted acid but only Lewis acid and has strong solid basicity.

[0064] (4) Platinum loading process Next, for 1 g of the zeolite catalyst after firing, a dinitrodiammineplatinum(II) nitrate solution containing 4.557% by mass of platinum (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., [Pt(NH3)2(NO2)2] / HNO3) was added, and platinum was impregnated and supported so that the supported amounts of platinum were 0.2% by mass, 0.5% by mass, 1.0% by mass, and 2.0% by mass, respectively. Then, it was dried overnight at 130 °C and calcined in air at 550 °C for 3 h to prepare a Pt / [Zn]-MFI catalyst, which is a zeolite-supported platinum catalyst on which 0.2% by mass, 0.5% by mass, 1.0% by mass, and 2.0% by mass of platinum were supported, respectively.

[0065] [Catalyst Preparation Example 2] <Preparation of <Zn / [Si]-MFI Catalyst> Sodium hydroxide, tetraethyl orthosilicate (TEOS), tetrapropylammonium hydroxide (TPAOH), and ion-exchanged water were mixed (TEOS:TPAOH:ion-exchanged water = 1:0.12:70 (molar ratio)), and the prepared gel was stirred (aged) at 80 °C for 24 h. The obtained mixture was subjected to hydrothermal synthesis at 175 °C for 24 h and then washed repeatedly with water. Then, it was dried overnight at 130 °C and calcined at 550 °C for 3 h. As a result, silica lite containing no aluminum was obtained. Regarding the obtained silica lite, it was confirmed to have an MFI structure by X-ray diffraction measurement (X-ray source: CuKα, apparatus: RINT 2500 manufactured by Rigaku Corporation). Subsequently, zinc was impregnated and supported using an aqueous solution of 1M zinc nitrate hexahydrate so that the supported amount of zinc became 10.0% by mass, dried overnight at 130 °C, and calcined at 550 °C for 3 h to prepare a Zn / [Si]-MFI catalyst.

[0066] [Catalyst Preparation Example 3] <Preparation of Pt / MgAl2O4 Catalyst> 10.0 g of commercially available γ-alumina (Neobead GB-13, Mizusawa Chemical Industries) was mixed with an aqueous solution of 12.5 g of magnesium nitrate hexahydrate (Mg(NO3)2·6H2O, Wako Pure Chemical Industries, Ltd.) dissolved in 100 mL of water. The resulting mixture was stirred at 50°C for 180 minutes using an evaporator, and then the water was removed under reduced pressure. It was then dried overnight at 130°C, calcined at 550°C for 3 hours, and then calcined at 800°C for 3 hours. This resulted in an alumina-magnesia support with a spinel structure. The resulting alumina-magnesia support showed diffraction peaks at 2θ = 36.9, 44.8, 59.4, and 65.3 deg, which were derived from Mg spinel, by X-ray diffraction measurement (X-ray source: CuKα, device: Rigaku Corporation, RINT 2500). Next, dinitrodiammine platinum (II) nitric acid solution (Tanaka Kikinzoku Kogyo Co., Ltd., [P The catalyst was impregnated with platinum using a 1.0 mass% mixture of t(NH3)2(NO2)2 / HNO3, dried overnight at 130°C, and calcined at 550°C for 3 hours to prepare a Pt / MgAl2O4 catalyst.

[0067] [Production of cyclopentadiene] Using the catalysts obtained in Catalyst Preparation Examples 1 and 3, cyclopentadiene was produced.

[0068] Example 1 A tubular reactor was filled with 0.1 g of Pt / [Zn]-MFI catalyst carrying 1.0 mass% platinum, and the tubular reactor was connected to a fixed-bed flow reactor. The tubular reactor was heated to 550°C while flowing molecular hydrogen at 30 mL / min, and then held at that temperature for 1.0 h. Then, an olefin having a carbon number of 5 (1-pentene:1,3-pentadiene = 50:50 (mass ratio)) and nitrogen were each supplied to the tubular reactor as a raw material composition, and a cyclization dehydrogenation reaction was carried out at a reaction temperature of 500°C and normal pressure. The WHSV was 1.1 h. -1 The gas flow rate (mL / min) ratio of the raw material composition to nitrogen (N2) was 1:12.

[0069] At 0.5, 2.5, 4.5 and 6.5 hours after the start of the reaction, the products of the cyclization dehydrogenation reaction were analyzed using a gas chromatograph (FID-GC) equipped with a hydrogen flame detector. Based on the gas chromatogram, each component (unit: mass%) of the collected reaction product was quantified, and the total conversion rate of the raw materials (the sum of the conversion rates of each raw material, unit: mass%) and the cyclopentadiene yield (yield relative to the amount of the raw material olefin with a carbon number of 5 used, mass%) were calculated. The results are shown in Table 1. The total conversion rate was calculated by the following formula (1).

[0070] Total conversion rate (mass%) = (1-(C 生成1-ペンテン +C 生成1,3-ペンタジエン ) / (C 原料1-ペンテン +C 原料1,3-ペンタジエン ))×100 (1) In formula (1), C 原料1-ペンテン and C 原料1,3-ペンタジエン is the mass% of 1-pentene and 1,3-pentadiene contained in the raw material, C 生成1-ペンテン and C 生成1,3-ペンタジエン is the mass% of 1-pentene and 1,3-pentadiene contained in the product.

[0071] (Examples 2 to 11) The yield of cyclopentadiene was calculated in the same manner as in Example 1, except that the raw material composition, catalyst, WHSV, and gas flow rate ratio in Example 1 were changed as shown in Tables 2 to 5. The yield ratio of cyclopentadiene (yield of cyclopentadiene in a reaction time of 6.5 hours / yield of cyclopentadiene in a reaction time of 2.5 hours) was calculated from the yield of cyclopentadiene obtained. The results are shown in Tables 2 to 5.

[0072] (Examples 12 and 13 and Comparative Examples 1 to 3) The raw material conversion rate or the total raw material conversion rate, and the cyclopentadiene yield were calculated in the same manner as in Example 1, except that the raw material composition, catalyst, WHSV, and gas flow rate ratio in Example 1 were changed as shown in Tables 1 and 6. The results are shown in Tables 1 and 6.

[0073] [Table 1]

[0074] As shown in Table 1, when a reaction was carried out using a catalyst in which a precious metal was supported on the zeolite catalyst in which a transition metal was introduced into the zeolite framework in Example 1, the total conversion rate of the raw materials and the yield of cyclopentadiene tended to be higher than those in Comparative Example 1, in which a supported precious metal catalyst was not used as a support for a crystalline metallosilicate. Furthermore, with the catalyst of Example 1, the yield of cyclopentadiene was maintained high even after 6.5 hours had elapsed, and stable production of cyclopentadiene over reaction time was observed. On the other hand, the catalyst of Comparative Example 1 was deactivated by coke deterioration immediately after the start of the reaction, and the cyclopentadiene yield tended to remain low.

[0075] [Table 2]

[0076] Table 2 shows the effect of platinum content in the zeolite catalyst on the specific yield of cyclopentadiene. As shown in Table 2, even when the platinum content in the zeolite catalyst was 0.2 mass %, stable production of cyclopentadiene was observed over the reaction time.

[0077] [Table 3]

[0078] Table 3 shows the effect of WHSV on the specific yield of cyclopentadiene. As shown in Table 3, when WHSV is 0.5 to 5.0 h -1 Stable production of cyclopentadiene over reaction time was observed over a wide range of reaction temperatures.

[0079] [Table 4]

[0080] Example 1 in Table 1 and Example 8 in Table 4 show the effect of the content of the diolefin having a carbon number of 5 in the raw material composition on the yield ratio of cyclopentadiene. Here, the yield ratio of cyclopentadiene in Example 1 (6.5 hr / 2.5 hr) was 1.09. As shown in Example 1 of Table 1 and Example 8 of Table 4, even when the content of the diolefin having a carbon number of 5 in the raw material composition was 33% by mass and 50% by mass, stable production of cyclopentadiene was observed over the reaction time.

[0081] [Table 5]

[0082] Example 1 in Table 1 and Examples 9 to 11 in Table 5 show the effect of the flow rate ratio of gases supplied to the reaction system on the yield ratio of cyclopentadiene. As shown in Example 1 in Table 1 and Examples 9 to 11 in Table 5, even when molecular hydrogen was not supplied to the reaction system, stable production of cyclopentadiene was observed over the course of reaction time.

[0083] [Table 6]

[0084] As shown in Examples 12 and 13 in Table 6, even in the case of Example 1 in which only a monoolefin having a carbon number of 5 was used as the raw material composition, the raw material conversion rate and the cyclopentadiene yield were high, and stable production of cyclopentadiene was observed over the course of the reaction time. On the other hand, the methods of Comparative Examples 2 and 3 in Table 6 did not achieve as high a raw material conversion rate and a cyclopentadiene yield as those of Examples 12 and 13, and in particular, the method of Comparative Example 3 showed a decrease in the cyclopentadiene yield over time.

Claims

1. a cyclization / dehydrogenation step of contacting a raw material composition containing an olefin having a carbon number of 5 with a zeolite catalyst having an MFI structure to obtain a reaction product containing cyclopentadiene, The zeolite catalyst contains Zn atoms in the zeolite framework and has Lewis acidity and strong solid basicity. A method for producing cyclopentadiene.

2. The method for producing cyclopentadiene according to claim 1, wherein the raw material composition contains a diolefin having 5 carbon atoms.

3. 3. The method for producing cyclopentadiene according to claim 2, wherein the content of the diolefin having 5 carbon atoms in the raw material composition is 5 mass% or more.

4. A method for producing cyclopentadiene described in any one of claims 1 to 3, wherein the content of Zn atoms is 1 to 15 atom% relative to Si atoms.

5. The method for producing cyclopentadiene according to any one of claims 1 to 4, wherein the zeolite catalyst does not contain an alkali metal or contains an alkali metal in an amount of 1 atom % or less relative to Si atoms in the zeolite framework.

6. The method for producing cyclopentadiene according to any one of claims 1 to 5, wherein the zeolite catalyst supports Pt.

7. The method for producing cyclopentadiene according to any one of claims 1 to 6, wherein in the cyclization dehydrogenation step, a gas flow rate (ml / min) ratio between the raw material composition and molecular hydrogen supplied to a reaction system is 1:0.001 to 1:3.

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