Furonitrile compound production method and carbonate ester production method

Abstract

The present invention provides a method that makes it possible to selectively obtain a desired compound with high yield while shortening reaction time in regeneration of a nitrile compound by dehydration of an amide compound, and that also suppresses the generation of by-products.　This problem is solved by a furonitrile compound production method comprising a dehydration reaction for dehydration of a furamide compound, wherein the dehydration reaction has a contact step for bringing a diluent and the furamide compound in a gaseous phase into contact with a catalyst. (In formula (1), R1 and n are as defined in the description.)

Description

Method for producing furonitrile compounds and method for producing carbonate esters

[0001] The present invention relates to a method for producing a furonitrile compound and a method for producing a carbonate ester.

[0002] Carbonate ester is carbonate CO(OH) ２ is a general term for compounds in which one or both of the two hydrogen atoms in the above are substituted with an alkyl group or an aryl group, and has the structure RO-C(=O)-OR' (R and R' respectively represent a hydrogen atom, a saturated hydrocarbon group, an unsaturated hydrocarbon group, etc.).

[0003] Carbonate esters are extremely useful compounds, used as additives in gasoline to improve octane numbers, diesel fuel additives to reduce particles in exhaust gases, and as alkylating agents, carbonylating agents, and solvents in the synthesis of resins and organic compounds such as polycarbonates, urethanes, pharmaceuticals, and agricultural chemicals, as well as raw materials for electrolytes in lithium-ion batteries, lubricating oil raw materials, and oxygen scavengers to prevent rust in boiler piping.

[0004] Known conventional methods for producing carbonate esters include, for example, a process of reacting water, which is produced as a by-product in the reaction of alcohol with carbon dioxide, with a nitrile compound (see, for example, Patent Documents 1 to 3). These methods for producing carbonate esters also include a process of dehydrating an amide compound produced from water and the nitrile compound to regenerate the nitrile compound.

[0005] Such conventional methods for producing carbonate esters do not necessarily allow selective regeneration of nitrile compounds in a short time and in high yield, making it difficult to efficiently produce the target carbonate ester compound.

[0006] Patent Document 1: WO2015 / 099053 Patent Document 2: WO2020 / 022416 Patent Document 3: WO2022 / 181670

[0007] A primary object of the present invention is to provide a method for regenerating a nitrile compound by dehydration of an amide compound, which can selectively obtain the target compound in a high yield while shortening the reaction time and suppressing the generation of by-products. A further primary object of the present invention is to realize an efficient method for producing a carbonate ester by applying such a method for producing a nitrile compound.

[0008] The present inventors have investigated a method for producing a furonitrile compound by dehydrating a furamide compound, and have found that when a furamide compound and a diluent are brought into contact with a catalyst in the vapor phase, the reaction rate can be significantly improved and the reaction time can be shortened, while the generation of by-products can be suppressed and the target compound can be selectively obtained in a high yield.

[0009] According to the present invention, the regeneration rate of a furamide compound to a furonitrile compound by dehydration reaction can be improved. Furthermore, in the method of the present invention for producing a carbonate ester from carbon dioxide and an alcohol, which incorporates such a dehydration reaction step, excellent effects such as efficient production of a carbonate ester can be realized.

[0010] The present invention includes, for example, the following: [1] A method for producing a furonitrile compound, comprising a dehydration reaction of dehydrating a furamide compound represented by the following formula (1), wherein the dehydration reaction comprises a contacting step of contacting the furamide compound and a diluent with a catalyst in a gas phase: In formula (1), R １ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxyl group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 6 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a cycloalkoxyl group having 6 to 20 carbon atoms which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, or a cyclic compound group having a 3 to 20 membered ring which contains at least two different elements in the ring and which may have a substituent, and n represents an integer of 0 to 3. [2] The R １is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. [3] The method for producing a furonitrile compound according to [1] or [2] above, wherein in the contacting step, the temperature at which the furamide compound and the diluent are brought into contact with the catalyst is 150°C or higher. [4] The method for producing a furonitrile compound according to any of [1] to [3] above, for example, [1] above, wherein the pressure of the reaction system in the contacting step is 101.3 kPa or lower. [5] The method for producing a furonitrile compound according to any of [1] to [4] above, for example, [1] above, wherein the catalyst contact time of the furamide compound in the gas phase is 0.001 seconds or longer and shorter than 10 seconds. [6] The method for producing a furonitrile compound according to any of [1] to [5] above, for example, [1] above, wherein the catalyst contains an alkali metal.

[0011] [7] The method for producing a furonitrile compound according to any one of the above [1] to [6], for example, the above [1], wherein the diluent contains at least one of a solvent and an inert gas. [8] The method for producing a furonitrile compound according to the above [7], wherein the solvent contains at least an aromatic compound. [9] The method for producing a furonitrile compound according to the above [8], wherein the aromatic compound is represented by the following formula (2): (In formula (2), R ２are each independently selected from an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, and an aryl group having 6 to 30 carbon atoms which may have a substituent, and a is an integer from 1 to 6.

[10] A method for producing a furonitrile compound according to [8] or [9] above, for example [8] above, wherein the aromatic compound has one or two aromatic rings and one or more groups selected from an alkyl group, an alkoxy group, and an aryloxy group.

[11] A method for producing a furonitrile compound according to any of [8] to

[10] above, for example [8] above, wherein the aromatic compound contains at least one of phenyl ether, 1,3,5-trimethylbenzene, p-cymene, and anisole.

[12] A method for producing a furonitrile compound according to any of [7] to

[11] above, for example [7] above, wherein the solvent is compatible with the furamide compound.

[13] The method for producing a furonitrile compound according to any one of the above [7] to

[12] , for example, the above [7], wherein a vaporized inert gas is used in the contact step.

[14] The method for producing a furonitrile compound according to any one of the above [7] to

[13] , for example, the above [7], wherein the inert gas contains at least nitrogen gas.

[0012]

[15] A method for producing a carbonate ester, comprising: a first reaction step including a carbonate ester production reaction in which an alcohol and carbon dioxide are reacted in the presence of a furonitrile compound to produce a carbonate ester and water, and a hydration reaction in which the produced water is hydrated with the furonitrile compound to produce a furamide compound; and a second reaction step in which, after separating the furamide compound from the reaction system of the first reaction step, the furamide compound is regenerated from the furamide compound by a dehydration reaction comprising a contact step according to any one of [1] to

[14] above, wherein at least a portion of the furonitrile compound regenerated in the second reaction step is used in the first reaction step.

[16] A method for producing a carbonate ester according to

[15] above, wherein a catalyst containing cerium oxide is used in the carbonate ester production reaction.

[17] A method for producing a carbonate ester according to

[15] or

[16] above, for example,

[15] above, wherein the alcohol comprises an alcohol having 1 to 6 carbon atoms.

[0013] According to the present invention, aromatic nitrile compounds such as furonitrile and its analogs can be efficiently produced (regenerated) from aromatic amide compounds such as furamide and its analogs. Specifically, in the dehydration reaction of the furamide compound for the regeneration, the generation of by-products can be suppressed, the target compound can be selectively obtained in high yield, and the reaction rate can be improved. Therefore, according to the present invention, the reaction time for the dehydration reaction to regenerate furamide compounds can be significantly shortened compared to conventional methods. Furthermore, in the dehydration step using a gas-phase reaction, the reaction vessel can be made smaller than in conventional dehydration steps of aromatic amide compounds using liquid-phase reactions. Therefore, according to the present invention, the process for regenerating aromatic nitriles such as furonitrile compounds from aromatic amide compounds such as furamide compounds can be easily commercialized. Furthermore, according to the present invention, by producing furonitrile compounds as described above, an efficient method for producing carbonate esters can also be realized.

[0014] 1 is an example of an apparatus for producing a carbonate ester. 2 is a schematic diagram showing an apparatus for producing 2-furonitrile having a vaporizer and a reactor in an example.

[0015] Preferred embodiments of the present invention will be described in detail below.

[0016] <1. Method for Producing Furonitrile Compound> In the method for producing a furonitrile compound of the present invention, an aromatic amide compound such as a furamide compound is dehydrated in a gas phase to convert it into an aromatic nitrile compound such as a furamide compound. That is, the method for producing a furonitrile compound of the present invention involves, for example, a contact step in which the furamide compound is brought into contact with a catalyst supporting a basic metal oxide in the gas phase, preferably at high temperature, to cause a dehydration reaction and produce the furonitrile compound.

[0017] (Substrate for Dehydration Reaction) The dehydration reaction of a furamide compound in the method for producing a furonitrile compound is represented by the following formula (1). In the above formula (1), R １ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxyl group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 6 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a cycloalkoxyl group having 6 to 20 carbon atoms which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, or a cyclic compound group having a 3 to 20 membered ring which contains at least two different elements in the ring and which may have a substituent. １ Examples of the substituent that can be contained in the general formula (1) R include a halogen atom, a hydroxy group, a carboxy group, a cyano group, an amide group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, and an alkoxy group having 1 to 10 carbon atoms. １ The number of carbon atoms in the formula (1) is the total number of carbon atoms including the number of carbon atoms in the substituents. In addition, n in the formula (1) represents an integer of 0 to 3. In the formula (1), n ​​is 2 or more, and the furamide compound has a plurality of substituents R １ When the １ are each independently selected from the above options. １The same is true for .

[0018] R in formula (1) １ is preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. １ is more preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 6 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms. １ is more preferably any one of a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, an n-propyl group, a t-butyl group, an n-butyl group, an isobutyl group, a cyclohexyl group, a phenyl group and a naphthyl group. １ is particularly preferably R １ is a hydrogen atom, a methyl group, or an ethyl group. Furthermore, n in the above formula (1) is preferably any of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0019] Preferred specific examples of the furamide compound include furamide, ie, 2-furamide, 3-furamide, etc., and preferred specific examples of the furonitrile compound include furonitrile, ie, 2-furonitrile, 3-furonitrile, etc.

[0020] (Other Reaction Substrates) As described above, furonitrile compounds are obtained by the dehydration reaction of furoamide compounds. However, aromatic amide compounds that can be used in the above-described method for producing aromatic nitrile compounds other than furonitrile compounds include amide compounds having an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring, or an anthracene ring, or a heteroaryl ring. Among these aromatic amide compounds, those having a heteroaryl ring, i.e., heteroaryl amide compounds, are preferably used. Examples of heteroaryl amide compounds include amide compounds having a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring, a triazine ring, a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, a pyrazole ring, or an oxazole ring. Preferred specific examples of heteroaryl amide compounds include those having a pyridine ring, such as the above-described pyridinecarboxamides (2-pyridinecarboxamide, 3-pyridinecarboxamide, and 4-pyridinecarboxamide). Furthermore, target compounds produced by the production method of the present invention may also include aromatic nitrile compounds other than furonitrile compounds. For example, aromatic nitrile compounds other than furonitrile compounds include products of dehydration reactions corresponding to the above-described aromatic amide compounds. Therefore, specific examples of aromatic nitrile compounds that can be produced by the method of the present invention include heteroaryl nitrile compounds. Preferred specific examples of heteroaryl nitrile compounds include those having a pyridine ring, such as cyanopyridines (2-cyanopyridine, 3-cyanopyridine, and 4-cyanopyridine).

[0021] (Catalyst) Here, the catalyst used in the dehydration reaction of the present invention preferably contains an oxide of an alkali metal (K, Li, Na, Rb, Cs). In particular, it is preferable to use a catalyst containing an oxide of at least one of Na, K, Rb, and Cs (cesium) as the catalyst used in the reaction. Furthermore, as a support for the catalyst, any substance that is generally used as a catalyst support can be used, but as a result of examining various supports, it has been found that a support such as SiO ２ , and ZrO ２ It is preferable to include any one of the following.

[0022] The catalyst used in the dehydration reaction of the present invention can be produced by the following method, for example: ２ In this case, commercially available powder or spherical SiO ２ It is preferable to use a sieve having a particle size of, for example, 4.0 mm or less so that the active metal can be uniformly supported, and to remove moisture, to carry out pre-baking in air at 700°C for 1 hour. ２ There are various types of catalysts, but catalysts with a larger specific surface area are preferred because they can disperse the active metals more highly and improve the production amount of furonitrile compounds. ２ However, the specific surface area of ​​the catalyst after preparation is preferably SiO ２ and the interaction with the active metal, etc. ２ In this case, the specific surface area of ​​the catalyst after production may be less than 150 m ２ The metal oxide serving as the active species can be supported by an impregnation method such as an incipient wetness method or an evaporation-to-dryness method.

[0023] The metal salt that serves as the catalyst precursor is preferably water-soluble, and in the case of an alkali metal, various compounds such as carbonates, hydrogen carbonates, chlorides, nitrates, silicates, etc. The catalyst can be used by impregnating a carrier with an aqueous solution of a basic metal precursor, followed by drying and calcination. The calcination temperature varies depending on the precursor used, but is preferably 400 to 600°C.

[0024] Furthermore, the catalyst used in the present invention is SiO ２ , ZrO ２ A catalyst in which only one or more alkali metal oxides are supported on a carrier made of one or two of the above is preferred, but it may contain inevitable impurities other than the above elements that are mixed in during the catalyst production process, etc. However, it is desirable to avoid the mixing of impurities as much as possible.

[0025] The catalyst preferably used in the present invention, in which a metal oxide serving as an active species is supported on a carrier, may be in the form of either a powder or a molded body, and in the case of a molded body, it may be in any shape such as a sphere, pellet, cylinder, ring, wheel, granule, etc. The catalyst may also be used by being fixed to a support structure such as a honeycomb.

[0026] There are no limitations on the size of the carrier; however, when a spherical carrier is used, the average diameter of the catalyst particles (carrier diameter) is preferably within the range of 0.01 to 8.0 mm, more preferably 0.03 to 6.0 mm, even more preferably 0.05 to 5.0 mm, particularly preferably 0.07 to 1.0 mm, and even more preferably 0.075 to 0.150 mm. Thus, by using a catalyst with a carrier diameter relatively larger than the average diameter of catalyst particles (carrier diameter) used in a liquid-phase reaction, a flow path for the reactant in a gas-phase reaction can be secured, ensuring a high space velocity. However, when a fluidized bed is used in a gas-phase reaction, a catalyst with a relatively small particle size is preferred so that the catalyst can be stirred with a small gas flow rate. When a fixed bed is used in a gas-phase reaction, a relatively large particle size and shape are preferred so that pressure loss is minimized. The carrier diameter, i.e., the average diameter of the catalyst particles, refers to the average diameter of the entire catalyst particle, including the active component of the catalyst and the carrier. The diameter of the catalyst carrier is a value measured by a sieving method based on the general rules for sieving test methods specified in JIS Z8815.

[0027] The amount of catalyst supported may be set as appropriate, and the amount of active species such as alkali metal oxides supported in terms of metal, based on the total catalyst weight, is preferably 0.05 to 2.0 mmol / g, more preferably 0.10 to 1.5 mmol / g, and even more preferably 0.30 to 1.0 mmol / g. The amount of catalyst used during the reaction may also be set as appropriate.

[0028] (Reaction Method and Reaction Vessel) In the process for producing a furonitrile compound of the present invention, it is preferable to use a gas-phase reaction in which a gaseous or mist-like amide compound is passed through a catalyst bed together with a diluent, and for example, a fixed-bed or fluidized-bed gas-phase reaction apparatus can be applied. In this manner, in the contact step in which a furamide compound is brought into contact with a catalyst in the gas phase, it is preferable to use a furamide compound in a completely vaporized state, but it is also possible to use a furamide compound in a state in which liquid droplets (mist) are partially contained in the gas.

[0029] The method for producing a furonitrile compound is preferably carried out while removing by-product water produced by the dehydration reaction. As a result of extensive studies by the present inventors, it has been found that, for example, by attaching a vaporization chamber to the top of a reaction tube containing a catalyst, dropping a furamide compound into the vaporization chamber, and passing the amide compound in a gas phase through a catalyst layer within a short period of time, it is possible to increase the amount of furonitrile compound produced and suppress the production of by-products.

[0030] (Diluent) In the above-described dehydration reaction, it is preferable to use a diluent. In particular, it is preferable to use at least one of an inert gas and a solvent, which will be described in detail later, as the diluent in the dehydration reaction. The diluent is primarily used to reduce the frequency of contact between the water produced when the furamide compound is vaporized and reacted with the catalyst and the unreacted furamide compound or the furonitrile compound, which is the reaction product, and to reduce the production of by-products such as pyridine. Therefore, an inert gas can also be used as the diluent. Furthermore, if the diluent is compatible with the furamide compound in the liquid phase, it can be mixed with a compatible diluent and then delivered in advance in the vaporization step of the furamide compound, thereby preventing blockages due to precipitation of the furamide compound. That is, the diluent may be an inert gas or a liquid that is not compatible with the furamide compound to be dehydrated, although a compatible liquid is preferred. The diluent compatible with the fluorocarbon compound in the liquid phase includes not only a diluent that can be mixed with the fluorocarbon compound in any ratio, but also a diluent that can dissolve the fluorocarbon compound only up to a predetermined solubility, and includes an amount of diluent that can dissolve the fluorocarbon compound to a concentration not exceeding the upper limit of the solubility at a predetermined temperature.

[0031] (Inert Gas) As described above, in the dehydration reaction, it is preferable to contact the catalyst with an inert gas in a gas phase together with the furamide compound. That is, the inert gas is preferably used in the dehydration reaction in a vaporized state. Specific examples of the inert gas used in the dehydration reaction include nitrogen gas and rare gases such as helium and argon, and nitrogen gas is preferably used. The flow rate of the inert gas will be described later.

[0032] (Solvent) In the above-described dehydration reaction, it is preferable to use a solvent. In particular, as described above, in the step of vaporizing a furamide compound, by preliminarily mixing the furamide compound with a solvent compatible with the compound and then feeding the mixture, it is possible to prevent clogging problems due to precipitation of the furamide compound. That is, the solvent is preferably one that is compatible with the furamide compound that is the target of the dehydration reaction. A solvent that is compatible with a furamide compound is not only a solvent that can be mixed with the furamide compound in any ratio, but also a solvent that can dissolve the target furamide compound only up to a predetermined solubility, and includes an amount of solvent that can dissolve the furamide compound to a concentration not exceeding the upper limit of the solubility at a predetermined temperature.

[0033] The solvent preferably contains at least an aromatic compound, and the aromatic compound preferably used is one represented by the following formula (2): In formula (2), R ２ are each independently selected from an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, and an aryl group having 6 to 30 carbon atoms which may have a substituent.

[0034] R in formula (2) ２ is preferably an alkyl group having 1 to 6 carbon atoms which may have a substituent, an alkoxy group having 1 to 6 carbon atoms which may have a substituent, or an aryl group having 6 to 18 carbon atoms which may have a substituent. ２ is more preferably any one of an alkyl group having 1 to 4 carbon atoms which may have a substituent, an alkoxy group having 1 to 3 carbon atoms which may have a substituent, and an aryl group having 6 to 12 carbon atoms which may have a substituent, and even more preferably any one of an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 or 2 carbon atoms which may have a substituent, and an aryl group having 6 to 8 carbon atoms which may have a substituent. In formula (2), a is an integer of 1 to 6, and a is preferably an integer of 1 to 4, and more preferably an integer of 1 to 3.

[0035] Examples of the substituent include a halogen atom, a hydroxy group, a carboxy group, a cyano group, an amide group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 carbon atoms, and an alkoxy group having 1 to 10 carbon atoms. The number of carbon atoms in the general formula (2) is the total number of carbon atoms, including the number of carbon atoms in the substituent.

[0036] The aromatic compound as a solvent preferably has one or two aromatic rings and one or more selected from alkyl groups, alkoxy groups, and aryloxy groups, more preferably a total of 1 to 3 alkyl and / or alkoxy groups. The aromatic compound also preferably has a plurality of aromatic rings, such as two, linked by ether bonds, for example, benzene rings.

[0037] The aromatic compound solvent used in the dehydration reaction preferably includes, for example, at least one of phenyl ether, 1,3,5-trimethylbenzene, p-cymene, and anisole. Other specific examples of the solvent include aromatic compounds including pyridine compounds, ketone compounds, ether compounds, ester compounds, alcohols, and the like, and the above-mentioned aromatic compounds are preferably used. Examples of furan compounds as solvents, i.e., compounds having a furan skeleton, include dimethoxyfuran. Examples of ketone compounds as solvents include cyclic ketone compounds such as cyclopentanone and cyclohexane, and acetone.

[0038] It is preferable to use a solvent consisting of only one or more substances selected from the above-mentioned compounds as the solvent for the dehydration reaction, but a mixed solvent further containing other compounds may also be used.

[0039] The solvent is preferably vaporized together with the fluoroamide compound and used in the dehydration reaction (contact step). Thus, it is preferable to use a solvent that is vaporized and used in the dehydration reaction. Furthermore, as will be described in detail later, since the solvent is used in a dehydration reaction that is preferably carried out at high temperatures, it is preferable that the solvent, which is preferably an aromatic compound, has a high spontaneous ignition temperature. For example, the solvent preferably has a spontaneous ignition temperature of 300°C or higher, 340°C or higher, 380°C or higher, or 400°C or higher, more preferably 430°C or higher or 450°C or higher, even more preferably 470°C or higher or 500°C or higher, and particularly preferably 550°C or higher. The boiling point of the solvent, which is preferably an aromatic compound, is not particularly limited, but the boiling point at atmospheric pressure is, for example, 20°C or higher to 300°C or lower, preferably 80°C or higher to 250°C or lower, and more preferably 110°C or higher to 200°C or lower.

[0040] (Conditions for Dehydration Reaction Including Contacting Step) As described above, the method for producing a furonitrile compound has a contacting step in which a furamide compound is contacted with a catalyst in the gas phase in the dehydration reaction. In the contacting step, the temperature at which the furamide compound and a diluent such as a solvent are contacted with the catalyst is, for example, 150°C or higher, preferably 180°C or higher, more preferably 200°C or higher, more preferably 220°C or higher, and particularly preferably 250°C or higher or 270°C or higher. The contact temperature is, for example, 150°C or higher and 550°C or lower, more preferably 200°C or higher and 520°C or lower, more preferably 220°C or higher and 500°C or lower, and particularly preferably 250°C or higher and 490°C or lower or 270°C or higher and 480°C or lower. The temperature at which the furamide compound or the like is contacted with the catalyst is, for example, the temperature in the vicinity of the catalyst layer in a reaction tube (reaction vessel) in which the catalyst is fixed.

[0041] The catalytic contact time of the furamide compound in the contact step, and the catalytic contact time of the mixed gas of the gaseous composition containing an inert gas, a solvent, etc., together with the furamide compound, when such gaseous composition is present, is preferably 0.001 second or more, or 0.005 second or more, for example, 0.01 second or more and less than 10 seconds. The catalytic contact time is more preferably 0.1 second or more and less than 5 seconds, and even more preferably 0.5 seconds or more and less than 2 seconds. The catalytic contact time is the average time required for the furamide compound gas or the mixed gas to pass through the catalyst layer, and is calculated by the formula: catalytic contact time (seconds) = catalyst layer height in reactor (m) ÷ linear gas velocity in reactor (m / second).

[0042] In the contact step, the molar ratio of the flow rate of the furamide compound to the flow rate of the gaseous composition of diluents such as an inert gas and a solvent is preferably 1:0 to 1:200, more preferably 1:1 to 1:100, and even more preferably 1:1 to 1:20. The space velocity (SV) of all gas components in the contact step is 1,000 to 50,000 (h －１ ), more preferably 1,500 to 30,000 (h －１ ), and more preferably 2,000 to 25,000 (h －１ When the contact step is carried out under reduced pressure, the space velocity (SV) of all gas components is 1,000 to 1,000,000 (h －１ ), more preferably 1,500 to 700,000 (h －１ ), and more preferably 1,900 to 504,000 (h －１ )

[0043] The dehydration reaction can be carried out under a pressure ranging from elevated pressure (e.g., 506.5 kPa) to atmospheric pressure (101.3 kPa) or reduced pressure (e.g., 101.3 to 1.0 kPa or less, e.g., stepwise reduced pressure from 101.3 to 1.0 kPa to 0.1 kPa), but is not particularly limited thereto. It is preferable to carry out the dehydration reaction under reduced pressure. The reaction pressure in the dehydration reaction is preferably 101.3 kPa or less, more preferably 90 kPa to 1.0 kPa or 80 kPa to 5.0 kPa, even more preferably 70 kPa to 10 kPa or 60 kPa to 20 kPa, and particularly preferably 50 kPa to 30 kPa.

[0044] It is also preferable to dehydrate the furamide compound in a liquid state before vaporization. When using molecular sieves as a dehydrating agent, there are no particular limitations on the type or shape, but for example, those with high water absorption such as 3A, 4A, or 5A, which are spherical or pellet-shaped, can be used. For example, Zeolum manufactured by Tosoh Corporation can be suitably used.

[0045] (Examples of By-Products in Dehydration Reaction) In the dehydration reaction of a furamide compound, it is thought that furan and the like are by-produced due to decomposition of the furamide compound. However, the reaction solution after the dehydration reaction using the contact step of the present invention contains almost no by-products such as furan.

[0046] <2. Method for Producing Carbonate Ester Using Furonitrile Compound> In the regeneration of furoamide compound to furonitrile compound by dehydration reaction, by providing a gas phase contact step, the reaction rate can be significantly improved and the reaction time can be significantly shortened. As a result, the regeneration rate of furoamide compound to furonitrile compound by dehydration reaction and the CO 2 production rate using furonitrile compound can be significantly improved. ２It has become possible to balance the reaction rate and the rate of synthesis of carbonate ester from alcohol, and these reactions can be established as a series of commercial processes. Based on this, the present inventors have applied this knowledge to the production of carbonate esters, and have conceived the production method of carbonate esters described below.

[0047] (First Reaction Step) In the first reaction step of the method for producing a carbonate ester of the present invention, for example, CeO ２ The present invention includes a reaction in which an alcohol is directly reacted with carbon dioxide in the presence of a solid catalyst containing, for example, cerium oxide and a furonitrile compound to produce a carbonate ester (carbonate ester production reaction).

[0048] In this process, when alcohol and carbon dioxide are reacted, water is also produced in addition to a carbonate ester. However, a furonitrile compound present in the reaction system reacts with the produced water to produce a furoamide compound, and the produced water can be removed or reduced from the reaction system. In this way, by efficiently removing water from the reaction system, it is possible to promote the production of a carbonate ester. For example, as shown in the following formula:

[0049] (Alcohol) Here, the alcohol may be any alcohol selected from one or more of primary alcohols, secondary alcohols, and tertiary alcohols. For example, methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, allyl alcohol, 2-methyl-1-propanol, cyclohexanemethanol, benzyl alcohol, ethylene glycol, 1,2-propanediol, and 1,3-propanediol are preferred because they provide a high product yield and a fast reaction rate. The carbonate esters produced in this step are dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, diheptyl carbonate, dioctyl carbonate, dinonane carbonate, diallyl carbonate, di-2-methyl-propyl carbonate, dicyclohexanemethyl carbonate, dibenzyl carbonate, ethylene carbonate, 1,2-propylene carbonate, and 1,3-propylene carbonate, respectively. Furthermore, in the first reaction step, it is preferable to use an alcohol having 1 to 6 carbon atoms, and it is more preferable to use an alcohol having 2 to 4 carbon atoms. In particular, when the resulting carbonate ester is used as a raw material for diaryl carbonate, it is preferable to adjust the carbon number of the alcohol to fall within the above-mentioned range. Furthermore, it is preferable to use a monohydric or dihydric alcohol in the first reaction step.

[0050] (Carbonate Ester Production Catalyst) In the first reaction step for producing a carbonate ester, CeO ２ and ZrO ２ It is preferable to use either one or both of the solid catalysts. For example, CeO ２ Chisel, ZrO ２ Only CeO ２ and ZrO ２ or a mixture of CeO ２ and ZrO ２ Solid solutions and composite oxides of these are preferred, and CeO ２ It is preferable to use only CeO ２ and ZrO ２ The solid solutions and composite oxides of CeO ２ and ZrO２ The mixing ratio is basically 50:50, but the mixing ratio can be changed as appropriate.

[0051] Here, the catalyst used in the first reaction step may be in the form of either a powder or a molded body, and in the case of a molded body, it may be in the form of a sphere, pellet, cylinder, ring, wheel, granule, or the like.

[0052] (Carbon dioxide) The carbon dioxide used in the present invention is not only that prepared as an industrial gas, but also that separated and recovered from exhaust gases from factories manufacturing various products, steel mills, power plants, etc.

[0053] (Solvent in Carbonate Ester Production Reaction) In the carbonate ester production reaction, it is preferable to use a solvent having a boiling point higher than that of the amide compound to be produced. More preferably, the solvent in the carbonate ester production reaction contains at least one of dialkylbenzene, alkylnaphthalene, and diphenylbenzene. Specific examples include barrel process oil B28AN and barrel process oil B30 (manufactured by Matsumura Oil Co., Ltd.), which contain components such as dialkylbenzene, alkylnaphthalene, and diphenylbenzene.

[0054] (Distillation separation) After the reaction, the main product, the carbonate ester, the by-product, the furamide compound, the unreacted furonitrile compound, and CeO ２ The solid catalyst can be separated by distillation to recover the product.

[0055] (Second Reaction Step) Next, the second reaction step in the present invention will be described. In the second reaction step, the furamide compound produced as a by-product in the first reaction step is preferably separated from the system after the carbonate ester production reaction, and then subjected to a dehydration reaction to produce a furonitrile compound. The second reaction step corresponds to the above-mentioned method for producing a furonitrile compound. That is, in the second reaction step for producing a carbonate ester, a furonitrile compound is produced from a furamide compound by the method described in the above section on the method for producing a furonitrile compound, thereby allowing the furonitrile compound to be regenerated. Therefore, details of the second reaction step will be omitted.

[0056] (Reuse of Furonitrile Compound) The furonitrile compound regenerated in the second reaction step can be reused in the first reaction step (hydration reaction).

[0057] According to the present invention, as described above, by carrying out the dehydration reaction of a furamide compound in a gas phase, it is possible to efficiently regenerate a furonitrile compound from the furamide compound while suppressing the generation of by-products. Furthermore, for example, by fixing a catalyst in a reaction tube, the step of solid-liquid separation of the catalyst is not necessary, and the recovery of the furonitrile compound is also facilitated. Thus, in the present invention, it is possible to selectively regenerate a furonitrile compound from a furamide compound, and to proceed with a series of reactions while separating each component only by distillation separation without solid-liquid separation of the catalyst, thereby realizing an efficient process as will be described in detail later.

[0058] <3. Carbonate Ester Production Apparatus> Next, the carbonate ester production apparatus used in the present invention will be described in more detail with reference to the following specific examples. Figure 1 shows an example of a suitable facility. In the following specific example, 2-furamide is used as the furamide compound and 2-furonitrile is used as the furonitrile compound, but the present invention is not limited to these.

[0059] (First Reaction Step) In the first reaction step, raw materials, alcohol (1-propanol (PrOH); liquid phase), 2-furonitrile (2-FN; liquid phase), and carbon dioxide (CO ２ ; liquid phase, which may be supplied via a booster pump) is fed to the raw material feed pipe 31, CO ２ Collection tower top CO ２ Transfer piping (CO ２ CO at the top of the recovery tower ２ The raw material mixture is continuously supplied to the carbonic acid ester recovery tower via a top liquid transfer pipe (liquid transfer pipe on the top side of the carbonic acid ester recovery tower) 15, a carbonic acid ester recovery tower top liquid transfer pipe (liquid transfer pipe on the top side of the carbonic acid ester recovery tower) 19, and an amide separation tower top liquid transfer pipe (liquid transfer pipe on the top side of the amide separation tower) 21. ２ and ZrO ２ Dipropyl carbonate (DPrC) is synthesized by circulating the reaction mixture between a fixed-bed flow-type carbonate ester reactor 2 (first reaction section) in which a solid catalyst (solid phase) such as either one or both of the above is fixed to a support material and a buffer tank 1 via first and second reaction liquid circulation pipes 11 and 12 using a pump (not shown). The reaction liquid containing DPrC is continuously extracted from the second reaction liquid circulation pipe 12 in an amount equal to the amount of raw material supplied to the buffer tank 1, recovered via pipe 13, and sent to the DPrC recovery step. PrOH and CO ２ are recovered from the reaction liquid and are transferred to the carbonic acid ester recovery tower overhead liquid transfer pipe 19 and CO ２ Collection tower top CO ２ It can be reused by transferring it to the buffer tank 1 via the transfer pipe 15. As 2-furonitrile, for example, new 2-furonitrile is used at the start of the reaction, but 2-furonitrile regenerated from 2-furamide in the amide separation column 6 may be separated and purified, and transferred to the buffer tank 1 via the amide separation column top liquid transfer pipe 21, for reuse.

[0060] For example, CeO ２ and ZrO ２As the apparatus for directly synthesizing a carbonate ester (carbonate reactor 2) using the above as a solid catalyst, any of a batch reactor, a semi-batch reactor, a continuous tank reactor, and a flow reactor such as a tubular reactor may be used. However, a fixed bed reactor is preferred because if the catalyst is fixed in the reactor, there is no need to filter and separate the catalyst.

[0061] (Reaction Solution Temperature) The reaction solution temperature in the carbonate ester reactor 2 is preferably 50 to 300°C. If the reaction solution temperature is below 50°C, the reaction rate is low, and both the carbonate ester synthesis reaction and the hydration reaction with 2-furonitrile hardly proceed, resulting in low carbonate ester productivity. Furthermore, if the reaction solution temperature exceeds 300°C, the reaction rate of each reaction increases, but the carbonate ester is more likely to decompose or denature, and 2-furoamide is more likely to react with alcohol, resulting in a low carbonate ester yield. The reaction solution temperature is more preferably 100 to 150°C. However, since the ideal reaction solution temperature is thought to vary depending on the type and amount of solid catalyst and the amounts and ratios of the raw materials (alcohol, 2-furonitrile), it is desirable to set optimal conditions as appropriate. Furthermore, since the preferred reaction solution temperature is 100 to 150°C, it is desirable to preheat the raw materials (alcohol, 2-furonitrile, etc.) with steam or the like upstream of the carbonate ester reactor.

[0062] (Reaction Pressure) The reaction pressure in the carbonate ester reactor 2 is preferably 0.1 to 20 MPa (absolute pressure). If the reaction pressure is less than 0.1 MPa (absolute pressure), a pressure reducing device is required, which not only makes the equipment complicated and costly, but also requires power energy for reducing the pressure, resulting in poor energy efficiency. If the reaction pressure exceeds 20 MPa, the hydration reaction with 2-furonitrile does not proceed easily, resulting in poor yield of carbonate ester, and also requires power energy for increasing the pressure, resulting in poor energy efficiency. From the viewpoint of increasing the yield of carbonate ester, the reaction pressure is more preferably 0.5 to 15 MPa (absolute pressure), and even more preferably 1.0 to 10 MPa (absolute pressure).

[0063] (Amount of 2-furonitrile) For aromatic nitrile compounds such as 2-furonitrile used in the hydration reaction, the amount of the raw material alcohol and CO ２ It is preferable to use a molar amount of 0.1 to 5 times the theoretical molar amount of water produced as a by-product in the reaction with CO, and it is preferable to introduce the compound into the reactor before the reaction. More preferably, the molar amount of the aromatic nitrile compound such as 2-furonitrile is the same as the theoretical molar amount of the raw material alcohol and CO. ２ The molar amount of the aromatic nitrile compound such as 2-furonitrile is preferably 0.2 to 3 times, and particularly preferably 0.3 to 1.5 times, the theoretical molar amount of water produced as a by-product in the reaction with the solid catalyst. If the molar amount of the aromatic nitrile compound such as 2-furonitrile is too small, the amount of 2-furonitrile and the like that contributes to the hydration reaction may be small, which may result in a poor yield of carbonate ester. On the other hand, introducing an aromatic nitrile compound such as 2-furonitrile in an excessive molar amount compared to the starting alcohol is undesirable because it increases side reactions such as 2-furonitrile. Furthermore, the ideal amount of alcohol and 2-furonitrile relative to the solid catalyst is thought to vary depending on the type and amount of the solid catalyst, the type of alcohol, and the ratio of alcohol to 2-furonitrile, so it is desirable to set optimal conditions appropriately.

[0064] (Separation of Reaction Products) The reaction products are preferably all separated by distillation. After the reaction in the carbonate ester reactor 2, the reaction liquid 13 is ２ It is sent to recovery tower 3 and CO ２ From the bottom of the recovery tower 3, CO ２ Recovery column: A mixture of PrOH, DPrC, 2-furonitrile, and 2-furamide is recovered through the column bottom liquid transfer pipe 14, and CO ２ From the top of recovery tower 3, CO ２ Collection tower top CO ２ CO ２ The recovered CO ２ is sent to a buffer tank 1 and recycled to the reaction in a carbonate ester reactor 2.

[0065] CO ２ The mixture recovered from the recovery tower 3 is CO ２The liquid is sent to the dehydrating agent separation column 4 via a recovery column bottom liquid transfer pipe 14, and a mixture of 2-furonitrile and 2-furamide is recovered from the bottom of the dehydrating agent separation column 4 via a dehydrating agent separation column bottom liquid transfer pipe 16, and PrOH and DPrC are recovered from the top of the dehydrating agent separation column 4 via a dehydrating agent separation column top liquid transfer pipe 17.

[0066] The mixture recovered from the bottom of the dehydrating agent separation column 4 is sent to the amide separation column 6 via the dehydrating agent separation column bottom liquid transfer pipe 16, and 2-furoamide (20) is recovered from the bottom of the amide separation column 6, and 2-furonitrile is recovered from the top of the amide separation column 6. The recovered 2-furonitrile is sent to the buffer tank 1 via the amide separation column top liquid transfer pipe 21 and recycled for the reaction in the carbonate ester reactor 2.

[0067] PrOH and DPrC recovered from the top of the dehydrating agent separation column 4 are sent to the carbonate ester recovery column 5 via a dehydrating agent separation column top liquid transfer pipe 17, DPrC is recovered from the bottom of the carbonate ester recovery column 5 via a carbonate ester recovery column bottom liquid transfer pipe 18, and PrOH is recovered from the top of the carbonate ester recovery column 5 via a carbonate ester recovery column top liquid transfer pipe 19. The recovered PrOH is sent to a buffer tank 1 and recycled for the reaction in the carbonate ester reactor 2.

[0068] (Second Reaction Step) In the second reaction step, 2-furonitrile is produced by a dehydration reaction of 2-furamide in a nitrile regeneration gas-phase reactor 8. The 2-furamide recovered in the amide separation column 6 is transferred to a vaporizer 7 through an amide separation column bottom liquid transfer pipe 20, where it is mixed with an inert gas, preferably nitrogen, and further heated to near the boiling point of the amide compound to form a gas or a gas-droplet mixture, which is transferred to the nitrile regeneration gas-phase reactor 8 through a vaporizer-nitrile regeneration gas-phase reactor connecting pipe 22. The type of the vaporizer 7 for vaporizing the amide compound and the like is not particularly limited, and any of an ejector-type vaporizer, a contact vaporizer, a bubbling device, or the like may be used.

[0069] In the nitrile compound production apparatus (nitrile regeneration gas-phase reactor 8) used in the present invention, a catalyst supported on a basic metal oxide is contacted in the gas phase with 2-furamide and an inert gas, preferably nitrogen, etc., to cause a dehydration reaction of 2-furamide. This dehydration reaction produces 2-furonitrile. When transporting the amide compound, the amide compound can be dissolved in a transfer solvent and then transported to prevent clogging problems. When using an amide transfer solvent, it is preferable to vaporize the solvent together with the amide to carry out the nitrile regeneration gas-phase reaction. In this case, solvent vapor can be used instead of an inert gas.

[0070] The type of the nitrile regeneration gas-phase reactor 8 is not particularly limited, and a gas-phase reaction in which a gaseous or mist-like amide compound is passed through a catalyst layer together with an inert gas or the like is preferred, and a gas-phase reaction apparatus such as a fixed bed or a fluidized bed can be applied. In this way, in order to bring 2-furamide into contact with a catalyst or the like in the gas phase and efficiently cause the dehydration reaction to proceed, the various reaction conditions described above for the above-mentioned dehydration reaction or the reaction conditions described in the Examples section below can be appropriately adopted.

[0071] The mixed gas containing 2-furonitrile is transferred from the gas phase reactor 8 to the H ２ Transfer to O separation device 9. ２ Water and nitrogen gas are separated from the mixed gas in the O separator 9, and the recovered 2-furonitrile and 2-furamide are mixed with H ２ O separation device H is transferred via high boiling point transfer pipe 24 ２ The 2-furonitrile is transferred from O separation device 9 to amide separation column 6. 2-Furamide is recovered from the bottom of amide separation column 6 via amide separation column bottom liquid transfer pipe 20 and transferred to vaporization device 7, and 2-furonitrile is recovered from the top of amide separation column 6. The recovered 2-furonitrile is sent to buffer tank 1 via amide separation column top liquid transfer pipe 21 and recycled for the reaction in carbonate ester reactor 2.

[0072] Furthermore, H ２ The nitrogen gas and water separated in the O separator 9 are mixed with H ２ O separation device N２ Send it to the recovery device 10, ２ The water is separated in the recovery device 10 and nitrogen gas is recovered. ２ The water separated in the recovery device 10 is ２ The water is sent to the outside of the carbonic acid ester unit through the recovery unit water transfer pipe 26. ２ The nitrogen gas recovered by the recovery device 10 is N ２ Recovery device N ２ By transferring the amide compound to the vaporizer 7 via the transfer pipe 27, it can be used in a gas phase reaction. When a solvent is used to transfer the amide compound, a separate process for recovering the solvent can be provided, and the solvent can be reused for transferring the amide compound. ２ O separation device 9 and N ２ The type of the recovery device 10 is not particularly limited, and any type of device such as a cooling device or a membrane separation device may be used.

[0073] As described above, in the present invention, not only can dehydration of an amide compound proceed through a contact step in the gas phase, but also the reaction product and the compound to be recycled can be separated by distillation or the like without the need for solid-liquid separation. Therefore, according to the present invention, it is possible to efficiently produce a carbonate ester with fewer production steps while simplifying the apparatus.

[0074] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. First, examples and comparative examples of the method for producing furonitrile will be described.

[0075] Example 1 (Example using a vaporizer (heat medium) and a reactor (mantle)) SiO as a carrier ２ (Fuji Silysia Chemical, CARiACT, G-6, (carrier diameter: 0.075 to 0.150 mm)) was pre-baked at 700°C for about 1 hour. Then, in order to support Cs as an alkali metal, CsNO was added so that the final Cs metal support amount was 0.5 mmol / g. ３ (manufactured by Wako Pure Chemical Industries, Ltd.) to prepare an aqueous solution of SiO ２ After that, it was dried at 110°C for about 6 hours and baked at 500°C for about 3 hours to form Cs ２ O / SiO ２A catalyst was obtained. The catalyst produced by the above-mentioned method was packed into a reaction tube 36 made of SUS316, having an inner diameter of 10.8 mm and a length of 35 cm (see FIG. 1). Furthermore, a vaporization chamber 33 made of SUS316, having an inner diameter of 10.8 mm and a length of 35 cm, and packed with a Dixon packing, was installed immediately above the reaction tube 36.

[0076] 60 g of 2-furamide (2-FA) was heated and mixed with 276 g of diphenyl ether (transfer solvent) in an oil bath at 180°C, and the resulting mixed solution of 2-FA and diphenyl ether was transferred to raw material container 31. The vaporization chamber 33 connected to raw material container 31 was heated with a heat medium double pipe 34, and the reaction tube 36 was heated with a mantle heater 35 (see Figure 1). The outlet piping of reaction tube 36 was maintained at 180°C. Dry ice / methanol cooling trap vessels 37 and 38, and a trap vessel 39 were installed to recover the reactants. The outlet piping of trap vessel 39 was connected to a vacuum pump 40, and the vaporization chamber 33 and reaction tube 36 were depressurized to 40 kPa. After the temperatures of the vaporization chamber and reaction tube stabilized at 280°C, plunger pump 32 was started, and the reaction was carried out for the time shown in the column for catalyst contact time in Table 1 below.

[0077] Examples 2 and 3 The same reaction apparatus as in Example 1 was used to carry out the dehydration reaction of 2-furamide in the same manner as in Example 1, except that the reaction conditions were changed as shown in Table 1 below. The trap vessels into which the reaction product produced by the dehydration reaction was collected are as follows: Example 1: Dry ice / methanol cooled trap vessels 37, 38, and trap vessel 39 Example 2: Dry ice / methanol cooled trap vessels 37, 38, and trap vessel 39 Example 3: Liquid nitrogen cooled trap vessel 7, dry ice / methanol cooled trap vessel 38, and trap vessel 39

[0078] Comparative Example 1 (Comparative Example Using Liquid Phase Reaction) Cs ２ O / SiO ２ Next, a two-necked round-bottom flask was used as a reactor, and a magnetic stirrer, the above-mentioned Cs ２ O / SiO ２A catalyst (0.2 g (Cs: 0.10 mmol), 2-furamide (2-FA, 1.116 g (10 mmol), manufactured by Tokyo Chemical Industry Co., Ltd.), and diphenyl ether (37.4367 g (220 mmol), manufactured by Tokyo Chemical Industry Co., Ltd.) were introduced. Furthermore, a thermometer and a first air-cooled tube were attached to the reactor, and a T-shaped tube equipped with a thermometer was attached to the upper end of the first air-cooled tube. A second air-cooled tube, a receiver, a trap, and a vacuum pump were connected to the T-shaped tube to form a reaction apparatus. The receiver and trap were cooled using dry ice / methanol. Subsequently, the pressure in the reactor was reduced to 53.2 kPa (399 Torr) using a vacuum pump, and the reaction solution was heated and maintained at a boiling state to carry out the reaction. The reaction started when the reaction solution temperature reached 143°C, and the reaction was carried out for 1.5 hours.

[0079] More detailed conditions for the above-mentioned catalytic reaction (dehydration reaction) are shown in Table 1. After the reaction was completed, the reaction product was recovered and analyzed by GC-FID.

[0080] The analytical conditions for the results of the catalytic reaction (dehydration reaction) are as follows: [Analysis conditions] (GC-FID) Shimadzu GC-2014, column: TC-17 (length 30 m, inner diameter 0.25 mm ID, liquid phase film thickness 0.25 μm), vaporization chamber temperature: 250° C., detector: 250° C., carrier N ２ Pressure: 175 kPa, column flow rate: 10.3 mL / min, split ratio: 5.0 Temperature program: [Hold at 40 ° C for 10 min] → [Heat to 250 ° C at 12 ° C / min] → [Hold at 250 ° C for 5 min]

[0081] [2-furonitrile yield (mol / min)] = (mol of produced 2-furonitrile recovered) / (reaction time (min)) [2-furonitrile yield (mol / day)] = (mol of produced 2-furonitrile recovered) / (reaction time (days)) [2-furonitrile yield] = [flow rate of produced 2-furonitrile (mol / min)] / [flow rate of raw material 2-furamide (mol / min)] [by-product furan yield] = [flow rate of produced furan (mol / min)] / [flow rate of raw material 2-furamide (mol / min)] [by-product rate] = [yield of by-product furan] / [yield of 2-furonitrile] [space velocity: SV (hr －１) ]=(Gas volume passing through the catalyst layer (L hr －１ )) / (amount of catalyst (L)) Gas amount: total gas volume of nitrogen, 2-FA (2-furamide), and solvent (L·hr －１ ) [Catalyst filling height (height of catalyst layer in reactor)]: height of catalyst filled in the reaction tube (m) [Catalyst contact time (seconds)] = [Catalyst filling height (m)] / [Linear velocity (gas linear velocity in reactor) (m / second)]

[0082] [Catalyst Carrier Diameter] The catalyst carrier diameter is a value measured by a sieving method in accordance with the general rules for sieving test methods specified in JIS Z 8815.

[0083] [Temperature of Vaporization Chamber / Reaction Tube and Reaction Temperature (Contact Temperature)] The reaction temperature in the dehydration reaction was measured by inserting a sheath tube made of SUS316 with a built-in thermometer from the bottom of the reaction tube exemplified as reaction tube 6 in the schematic diagram of the reaction apparatus in Fig. 1 to a position just below the catalyst layer. That is, the temperature just below the catalyst layer was measured, and the temperature before the raw materials were passed through was taken as the temperature of the vaporization chamber / reaction tube, and the temperature after the raw materials were passed through was taken as the reaction temperature (contact temperature).

[0084] [Detection of unknown component (UK detection)] When a compound whose molecular structure could not be determined (unknown component) was detected by the measurement method for the product of the contact reaction (dehydration reaction) described in the above [Analysis conditions] column, it was marked as "Yes", and when no unknown component was detected, it was marked as "No".

[0085] [Reaction Pressure (Differential Pressure)] For example, as shown in Fig. 2, digital pressure gauges were attached near the inlet of the reactor, i.e., near the inlet of vaporization chamber 33 [A: pressure at the top of the vaporizer], and near the outlet of the reactor, i.e., near the outlet of reaction tube 36 [B: pressure at the bottom of the catalyst layer], and the pressure was measured using these digital pressure gauges. In Table 1, the reaction pressure (differential pressure) is the difference between the measured pressures [A-B] (kPa), and the reaction pressure is the average of the inlet and outlet pressures [(A+B) / 2] (kPa), and the pressure values ​​are the average values ​​(kPa) of the samples.

[0086] [Gas volume velocity (V = (nRT) / P)] The gas volume velocity (V) was calculated according to the following formula: V = (nRT) / P) n: Sum of the amounts of nitrogen, 2-FA (2-furamide), and solvent (mol) R: Gas constant T: Reaction temperature (K: Temperature directly below the catalyst layer) P: Reaction pressure (Pa) The gas volume velocity (V) was measured to calculate the catalyst contact time (seconds), and the catalyst contact time [seconds] was calculated by the above formula, i.e., [Catalyst packing height (m)] / [Linear velocity (gas linear velocity in the reactor) (m / s)]. Catalyst contact time [seconds] = Catalyst volume [m ３ ]÷Gas volume velocity [m ３ / sec].

[0087] As is clear from the results of the Examples and Comparative Examples, the gas-phase dehydration reactions in the Examples achieved a high yield of 2-furonitrile despite a much shorter reaction time than the liquid-phase dehydration reactions in the Comparative Examples. That is, the yield of 2-furonitrile was 21% in the Comparative Examples, but was 45 to 62% in the Examples. Furthermore, the by-product production rate of furan was suppressed in the gas-phase dehydration reactions in the Examples.

[0088] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

[0089] 31 raw material container 32 plunger pump 33 vaporization chamber 34 heat medium double pipe 35 mantle heater 36 reaction tube 37, 38 cooling trap container 39 trap container 40 vacuum pump

Claims

1. A method for producing a furonitrile compound, comprising a dehydration reaction of dehydrating a furamide compound represented by the following formula (1), wherein the dehydration reaction comprises a contacting step of contacting the furamide compound and a diluent with a catalyst in a gas phase. (In formula (1), R １ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxyl group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 6 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a cycloalkoxyl group having 6 to 20 carbon atoms which may have a substituent, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, or a cyclic compound group having a 3 to 20 membered ring which contains at least two different elements in the ring and which may have a substituent, and n represents an integer of 0 to 3.

2. The above R １ The method for producing a furonitrile compound according to claim 1, wherein is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.

3. The method for producing a furonitrile compound according to claim 1, wherein in the contacting step, the temperature at which the furoamide compound and the diluent are brought into contact with the catalyst is 150°C or higher.

4. The method for producing a furonitrile compound according to claim 1, wherein the pressure of the reaction system in the contact step is 101.3 kPa or less.

5. The method for producing a furonitrile compound according to claim 1, wherein the catalyst contact time of the furamide compound in the gas phase is from 0.001 seconds to less than 10 seconds.

6. The method for producing a furonitrile compound according to claim 1, wherein the catalyst contains an alkali metal.

7. The method for producing a furonitrile compound according to claim 1, wherein the diluent contains at least one of a solvent and an inert gas.

8. The method for producing a furonitrile compound according to claim 7, wherein the solvent contains at least an aromatic compound.

9. The method for producing a furonitrile compound according to claim 8, wherein the aromatic compound is represented by the following formula (2): (In formula (2), R ２ are each independently selected from an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkoxy group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 6 to 30 carbon atoms which may have a substituent, and an aryl group having 6 to 30 carbon atoms which may have a substituent, and a is an integer from 1 to 6.

10. The method for producing a furonitrile compound according to claim 8, wherein the aromatic compound has one or two aromatic rings and one or more groups selected from an alkyl group, an alkoxy group and an aryloxy group.

11. The method for producing a furonitrile compound according to claim 8, wherein the aromatic compound includes at least one of phenyl ether, 1,3,5-trimethylbenzene, p-cymene, and anisole.

12. The method for producing a furonitrile compound according to claim 7, wherein the solvent is compatible with the furoamide compound.

13. The method for producing a furonitrile compound according to claim 7, wherein a vaporized inert gas is used in the contact step.

14. The method for producing a furonitrile compound according to claim 7, wherein the inert gas contains at least nitrogen gas.

15. A method for producing a carbonate ester, comprising: a first reaction step including a carbonate ester production reaction in which an alcohol is reacted with carbon dioxide in the presence of a furonitrile compound to produce a carbonate ester and water, and a hydration reaction in which the produced water is hydrated with the furonitrile compound to produce a furamide compound; and a second reaction step in which the furamide compound is separated from the reaction system of the first reaction step and then dehydrated, the dehydration reaction having a contact step according to any one of claims 1 to 14, to regenerate the furamide compound from the furamide compound, wherein at least a portion of the furamide compound regenerated in the second reaction step is used in the first reaction step.

16. The method for producing a carbonate ester according to claim 15, wherein a catalyst containing cerium oxide is used in the carbonate ester production reaction.

17. The method for producing a carbonate ester according to claim 15, wherein the alcohol includes an alcohol having 1 to 6 carbon atoms.