Carbonate ester manufacturing method and carbonate ester manufacturing apparatus

Abstract

To provide a method for producing a carbonate ester with high efficiency while removing by-product water from a reaction field without using a dehydrating agent or a chemical hydration agent under mild reaction pressure and to provide a device for producing a carbonate ester.SOLUTION: There are provided a method and a device for producing a carbonate ester in which a carbonate ester and by-product water are produced by reacting carbon dioxide and at least one alcohol selected from the group consisting of monovalent and divalent alcohols having a boiling point of more than 100°C under the conditions of a reaction temperature of 100°C or more and equal to or below the boiling point of the alcohols and the solvent in the presence of at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide and europium oxide and a solvent and the by-product water is removed from a reaction field by vaporization.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for producing a carbonate ester. [Background technology]

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

[0003] Carbonates are extremely useful compounds that are used as additives, such as gasoline additives to improve the octane number and diesel fuel additives to reduce particles in exhaust gases, as well as alkylating agents, carbonylating agents, and solvents in the synthesis of resins and organic compounds such as polycarbonates, polyurethanes, pharmaceuticals, and agricultural chemicals, as electrolytes for lithium batteries, as a raw material for lubricating oils, and as oxygen scavengers to prevent rust in boiler piping.

[0004] The mainstream method for producing carbonate esters in the past is to directly react phosgene with an alcohol as a carbonyl source. This method requires careful handling, such as transportation and storage, because phosgene is extremely harmful and highly corrosive, and it has been very costly to maintain and manage the production equipment and ensure its safety. In addition, when producing carbonate esters using this method, halogens such as chlorine are contained in the raw materials and catalyst, and the resulting carbonate esters contain trace amounts of halogens that cannot be removed by a simple purification process. In applications for gasoline additives, diesel additives, and electronic materials, there is a concern that halogens may cause corrosion, so a thorough purification process is required to reduce the amount of halogens present in trace amounts to an extremely small amount. Furthermore, since phosgene, which is extremely harmful to the human body, is used in this production method, strict administrative guidance has been given, such as not allowing the establishment of new production facilities for this production method, and a new production method that does not use phosgene is strongly desired.

[0005] In this context, as described in Non-Patent Document 1, a method for producing carbonate esters without using phosgene has been put into practical use, in which carbon dioxide is reacted with ethylene oxide or the like to synthesize a cyclic carbonate ester, which is then reacted with methanol to obtain dimethyl carbonate. This method is an excellent environmentally friendly method that hardly uses or generates corrosive substances such as hydrochloric acid, and is expected to have a reduction effect by incorporating carbon dioxide, which is a global warming gas and is required to be reduced, into the skeleton. However, as described in Patent Document 1, a major issue is how to effectively utilize the by-product ethylene glycol, etc. In addition, since it is difficult to safely transport ethylene, which is a raw material for ethylene oxide, and ethylene oxide, there is also a restriction that a plant for the carbonate ester production process must be located adjacent to a plant for the production process of these ethylene and ethylene oxide.

[0006] In addition, as described in Patent Documents 2, 3, and 4, methods are disclosed in which carbon dioxide is reacted with an alkylene oxide or an epoxide to synthesize a carbonate ester (polyether carbonate polyol or polycarbonate polyol). These methods are also excellent and environmentally friendly methods that are expected to reduce carbon dioxide, which is a global warming gas that is required to be reduced, by incorporating it into the skeleton. However, since a complex catalyst is used as a catalyst, there are problems such as a restriction on the upper limit of the operating temperature so that the complex catalyst does not decompose, it is not easy to separate the product and the catalyst after the reaction, and the higher the reaction pressure, such as 2 MPa to 6 MPa, the more advantageous it is.

[0007] Also, as described in Patent Document 5, a method for producing dimethyl carbonate by oxidizing methanol and carbon monoxide with oxygen in the liquid phase in the presence of a cuprous chloride catalyst has been disclosed. However, problems have been pointed out with this method, such as the need to handle carbon monoxide, which is harmful to the human body, the need for a purification step of the halogen from the resulting carbonate ester due to the presence of halogen in the catalyst as in the production method using phosgene, and the generation of a considerable amount of carbon dioxide as a by-product. On the other hand, Patent Document 6 discloses a method for producing urethane or carbonate from carbon dioxide and a dihydric alcohol, but this method uses a strongly basic nitrogen-containing compound as a catalyst, and this method has a problem of high environmental impact.

[0008] In order to solve the above problems, attempts have been made to remove the water by-produced together with the carbonate ester (dimethyl carbonate) from the system to release the reaction constraints. For example, research has been reported using acetal (Non-Patent Document 2) and 2,2-dimethoxypropane (Non-Patent Document 3) as hydrating agents together with a catalyst. However, this method has the characteristic that the reaction proceeds as the reaction pressure increases, and the reaction yield is very low at low pressures, and high productivity cannot be obtained unless the pressure is extremely high. This is presumably because the hydration reactions of acetal and 2,2-dimethoxypropane are expected to proceed in the liquid phase without catalytic action, and therefore do not depend on the CO2 pressure, and the reaction rate of the direct synthesis reaction of dimethyl carbonate determines the overall reaction rate. However, there were problems such as the methanol conversion rate increasing at high reaction pressures of 300 atmospheres (30 MPa) and 60 atmospheres (6 MPa), respectively, resulting in a very large amount of power energy required for pressure increase, resulting in poor energy efficiency.

[0009] Also, research using molecular sieves (solid dehydrating agents) has been reported (Patent Document 7, Non-Patent Document 4), but the process requires separating and circulating the reaction section (high pressure) and the dehydration section (normal pressure), which results in large energy consumption and the need for a large amount of solid dehydrating agent. As for solid catalysts used in the direct synthesis reaction of carbonate esters, various compounds have been investigated so far, including tin compounds such as dimethoxydibutyltin, thallium compounds such as thallium methoxide, nickel compounds such as nickel acetate, vanadium pentoxide, alkali carbonates such as potassium carbonate, and Cu / SiO2.

[0010] On the other hand, research has been reported on a reaction system in which cyclic carbonate (propylene carbonate) is directly synthesized from propylene glycol, a dihydric alcohol, and carbon dioxide in the presence of a solid catalyst using acetonitrile as a hydrating agent (Non-Patent Document 5). However, this reaction system is also significantly affected by the reaction pressure, and the reaction progresses as the reaction pressure increases. At low pressures, the reaction yield is extremely low, but at high pressures, where the equilibrium is favorable for the direct synthesis reaction of cyclic carbonate esters, the yield increases. It was confirmed that a reaction pressure of 100 atmospheres or more is desirable, and there were problems such as poor energy efficiency as mentioned above.

[0011] The present inventors have focused on a method for directly synthesizing a carbonate ester from a monohydric alcohol and carbon dioxide using a heterogeneous catalyst in the production of a carbonate ester, and have found for the first time that by using acetonitrile or benzonitrile as a hydrating agent to remove water produced as a by-product together with the carbonate ester from the system, high pressures such as 300 or 60 atmospheres as described in Non-Patent Documents 2 and 3 are not necessary, and the reaction is promoted under pressure close to normal pressure (see Patent Documents 8 and 9). However, when acetonitrile is used as a hydrating agent, by-products such as acetamide are produced and their uses are limited. Therefore, by adopting benzonitrile as a hydrating agent, the reaction proceeds more under pressure close to normal pressure in the reaction system, as in the case of acetonitrile, and the types of by-products are also reduced. In addition, it has been found that benzamide, the main by-product, itself has many uses, which has led to the invention.

[0012] Furthermore, the present inventors have intensively investigated the type of hydrating agent to further increase the amount of carbonate ester produced, and have found that by using 2-cyanopyridine or benzonitrile as the hydrating agent, the amount and rate of carbonate ester produced are significantly improved compared to the cases of acetonitrile or benzonitrile, the reaction proceeds easily under relatively low pressure close to normal pressure, and the reaction rate is very fast (see Patent Documents 10, 11, 12, and 13). However, a process for regenerating and reusing the by-product 2-picolinamide or benzamide was required (see Patent Documents 10, 11, 12, and 13). [Prior art documents] [Patent documents]

[0013] [Patent Document 1] WO2004 / 014840 publication [Patent Document 2] WO2006 / 103213 publication [Patent Document 3] JP 2015-28182 A [Patent Document 4] WO2013 / 010986 publication [Patent Document 5] EP365,083 publication [Patent Document 6] Japanese Patent Application Publication No. 5-117222 [Patent Document 7] JP 2001-247519 A [Patent Document 8] JP 2009-132673 A [Patent Document 9] JP 2010-77113 A [Patent Document 10] JP 2012-162523 A [Patent Document 11] JP 2009-213975 A [Patent Document 12] JP 2016-216361 A [Patent Document 13] JP 2016-216363 A [Non-patent literature]

[0014] [Non-Patent Document 1] Chemical Engineering, 68(1) (2004) 41 [Non-Patent Document 2] Polyhedron, 19 (2000) 573 [Non-Patent Document 3] Appl. Catal. A Gen, 237 (2002) 103 [Non-Patent Document 4] Eco Industry, 6 (2001) 11 [Non-Patent Document 5] Catal. Lett., 112, (2006) 187 Summary of the Invention [Problem to be solved by the invention]

[0015] As described above, there have been no reports of synthesizing a carbonate ester in high yield by reacting an alcohol with carbon dioxide in the presence of a solid catalyst under a mild reaction pressure such as normal pressure and removing by-product water from a reaction site without using a dehydrating agent or a chemical hydrating agent.

[0016] Therefore, an object of the present invention is to provide a method and an apparatus for producing a carbonate ester, which produce a carbonate ester highly efficiently under mild reaction pressure while removing by-product water from a reaction field without using a dehydrating agent or a chemical hydrating agent. [Means for solving the problem]

[0017] Means for solving the problem include the following aspects. [1] A method for producing a carbonate ester, comprising reacting carbon dioxide with at least one alcohol having a boiling point of more than 100°C, selected from the group consisting of monohydric and dihydric alcohols, in the presence of at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide, and a solvent, at a reaction temperature of 100°C or higher and not higher than the boiling points of the alcohol and the solvent, to produce a carbonate ester and by-product water, and removing the by-product water from a reaction site by evaporation. [2] The method for producing a carbonate ester according to [1], wherein the evaporated by-product water is removed from the reaction field by a carbon dioxide gas flow. [3] The method for producing a carbonate ester according to [1] or [2], wherein the alcohol is a monohydric alcohol having 4 to 10 carbon atoms. [4] The method for producing a carbonate ester according to [1] or [2], wherein the alcohol is a dihydric alcohol having 2 to 10 carbon atoms. [5] The method for producing a carbonate ester according to [4], wherein the dihydric alcohol is a dihydric alcohol having 4 to 6 carbon atoms. [6] The method for producing a carbonate ester according to any one of [1] to [5], wherein the solvent is an ether solvent. [7] The method for producing a carbonate ester according to any one of [1] to [6], wherein the solvent is a hydrophobic solvent. [8] a reaction step of supplying carbon dioxide and at least one alcohol having a boiling point of more than 100° C. and selected from the group consisting of monohydric and dihydric alcohols to a reactor in which at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide and a solvent are present, and reacting the carbon dioxide with the alcohol under conditions where the reaction temperature is 100° C. or higher and is equal to or lower than the boiling points of the alcohol and the solvent, to produce a carbonate ester and by-product water; A first cooling step in which the unreacted carbon dioxide, the unreacted alcohol, the by-product water and the solvent discharged as a gas phase from the reactor in the reaction step are cooled to separate the unreacted carbon dioxide as a gas phase and the unreacted alcohol, the by-product water and the solvent as a liquid phase; a first distillation step in which the unreacted alcohol, the by-product water, and the solvent separated as a liquid phase in the first cooling step are separated by distillation into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase; a second distillation step in which the carbonate ester, the unreacted alcohol, and the solvent discharged as a liquid phase from the reactor in the reaction step are distilled to separate them into the unreacted alcohol and the solvent as a gas phase and the carbonate ester as a liquid phase, or a second cooling step in which the carbonate ester, the unreacted alcohol, and the solvent discharged as a liquid phase from the reactor in the reaction step are cooled to separate them into the unreacted alcohol and the solvent as a liquid phase and the carbonate ester as a solid phase; having The unreacted carbon dioxide separated in the first cooling step, the unreacted alcohol and the solvent separated in the first distillation step, and the unreacted alcohol and the solvent separated in the second distillation step or the second cooling step are reused in the reaction step. A method for producing carbonate esters. [9] a separation step of separating a solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction step from the liquid phase; a catalyst regeneration step of regenerating the solid catalyst separated in the separation step; and The method for producing a carbonate ester according to [8], wherein the solid catalyst regenerated in the catalyst regeneration step is reused in the reaction step.

[10] a reaction tower having a reactor in which at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide and a solvent are present, in which carbon dioxide and at least one alcohol having a boiling point of more than 100° C. and selected from the group consisting of monohydric and dihydric alcohols are supplied to the reactor, and the carbon dioxide and the alcohol are reacted under conditions in which the reaction temperature is 100° C. or higher and is equal to or lower than the boiling points of the alcohol and the solvent to produce a carbonate ester and by-product water; A first cooling tower that cools the unreacted carbon dioxide, the unreacted alcohol, the by-product water, and the solvent discharged as a gas phase from the reactor in the reaction tower, and separates the unreacted carbon dioxide as a gas phase and the unreacted alcohol, the by-product water, and the solvent as a liquid phase; A first distillation tower that separates the unreacted alcohol, the by-product water, and the solvent separated as a liquid phase in the first cooling tower by distillation into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase; a second distillation tower which distills the carbonate ester, the unreacted alcohol and the solvent discharged as a liquid phase from the reactor in the reaction tower, and separates them into the unreacted alcohol and the solvent as a gas phase and the carbonate ester as a liquid phase, or a second cooling tower which cools the carbonate ester, the unreacted alcohol and the solvent discharged as a liquid phase from the reactor in the reaction tower, and separates them into the unreacted alcohol and the solvent as a liquid phase and the carbonate ester as a solid phase; Equipped with The unreacted carbon dioxide separated in the first cooling tower, the unreacted alcohol and the solvent separated in the first distillation tower, and the unreacted alcohol and the solvent separated in the second distillation tower or the second cooling tower are reused in the reaction tower. Carbonate ester manufacturing equipment.

[11] a separation tower for separating a solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction tower from the liquid phase; a catalyst regeneration tower for regenerating the solid catalyst separated in the separation tower; Further equipped with The apparatus for producing a carbonate ester according to

[10] , wherein the solid catalyst regenerated in the catalyst regeneration tower is reused in the reaction tower. Effect of the Invention

[0018] According to the present invention, it is possible to provide a method and an apparatus for producing a carbonate ester, which produce a carbonate ester highly efficiently under a moderate reaction pressure while removing by-product water from a reaction field without using a dehydrating agent or a chemical hydrating agent. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic configuration diagram showing a carbonic acid ester production apparatus according to a first embodiment. [Diagram 2] FIG. 4 is a schematic configuration diagram showing a carbonic acid ester production apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will now be described. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In numerical ranges described in stages, the upper limit or lower limit value described in a certain numerical range may be replaced with the upper limit or lower limit value of another numerical range described in stages. In a numerical range, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. The term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. A "combination of preferred aspects" is a more preferred aspect.

[0021] The method for producing a carbonate ester of the present invention is a method comprising reacting carbon dioxide with at least one alcohol having a boiling point of more than 100° C. and selected from the group consisting of monohydric and dihydric alcohols in the presence of at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide and a solvent, under conditions where the reaction temperature is 100° C. or higher and is lower than the boiling points of the alcohol and the solvent, to produce a carbonate ester and by-product water (see the scheme below), and removing the by-product water from the reaction site by evaporation.

[0022] [ka] [ka]

[0023] In the method for producing a carbonate ester of the present invention, the above-mentioned technique makes it possible to produce a carbonate ester highly efficiently under mild reaction pressure while removing by-product water from the reaction field without using a dehydrating agent or a chemical hydrating agent. The method for producing a carbonate ester of the present invention was discovered based on the following findings.

[0024] The present inventors have focused on a method for directly synthesizing a carbonate ester from an alcohol having a boiling point of over 100° C. and carbon dioxide in producing the carbonate ester. As a result, the present inventors have obtained the following findings. When carbon dioxide is introduced into the reaction system in the presence of at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide, and a solvent, and the reaction is carried out with an alcohol, the by-product water produced together with the carbonate ester can be removed from the reaction field by utilizing the difference in boiling points without using a dehydrating agent or a chemical hydrating agent. As a result, the reaction between carbon dioxide and an alcohol proceeds under a moderate reaction pressure, such as normal reaction pressure, without the need for high pressures such as 3 MPa (30 atm) or 6 MPa (60 atm) as described in Non-Patent Documents 2 and 3.

[0025] Based on the above findings, it has been found that the method for producing a carbonate ester of the present invention can produce a carbonate ester highly efficiently under mild reaction pressure while removing by-product water from the reaction field without using a dehydrating agent or a chemical hydrating agent.

[0026] Furthermore, in the method for producing a carbonate ester of the present invention, at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide is used, which makes it possible to solve problems that are encountered with conventional complex catalysts, such as the difficulty in separating the catalyst from products and the like after the reaction, and the limitation on the upper limit of the reaction temperature so as to prevent the catalyst itself from undergoing thermal decomposition.

[0027] The process for producing a carbonate ester of the present invention will now be described in more detail.

[0028] In the method for producing a carbonate ester of the present invention, in the reaction step, an alcohol having a boiling point of more than 100° C. is directly reacted with carbon dioxide in the presence of at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide, and a solvent, to produce a carbonate ester. In this reaction process, when an alcohol with a boiling point of over 100°C is reacted with carbon dioxide, water is also produced as a by-product in addition to the carbonate ester.

[0029] In this case, if the reaction conditions are such that the reaction temperature is 100°C or higher (i.e., above the boiling point of water) and below the boiling points of the alcohol and the solvent, the by-product water evaporates and is removed from the reaction site while the solvent and alcohol remain liquid, thereby promoting the production of carbonate ester. In addition, it is preferable to remove the evaporated by-product water from the reaction field by using a carbon dioxide gas flow.

[0030] Here, "removing by-product water from the reaction field by evaporation" includes not only removing all by-product water from the reaction field where the carbonate ester is produced (i.e., the region where the alcohol, the solid catalyst, and the solvent are present) but also including a portion of by-product water remaining in the reaction field. Note that the by-product water remaining in the reaction field can be separated by distillation.

[0031] (carbon dioxide) Carbon dioxide can be used not only when it is prepared as an industrial gas, but also when it is separated and recovered from exhaust gases from factories, steel mills, power plants, etc., where various products are manufactured.

[0032] (alcohol) As the alcohol, at least one alcohol selected from the group consisting of monohydric and dihydric alcohols is used.

[0033] Examples of the monohydric alcohol include 1-butanol, isobutyl alcohol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, and dodecanol. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, and trans-1,4-cyclohexenedimethanol.

[0034] Among these, the monohydric and dihydric alcohols are appropriately selected depending on the properties required for the target product, that is, the carbonate ester. From the viewpoints of boiling point and the proportion of carbon dioxide taken up in the product, alcohols having 2 to 10 carbon atoms are preferred, and alcohols having 4 to 6 carbon atoms are more preferred. Among monohydric and dihydric alcohols, monohydric alcohols are preferred from the viewpoint of producing polycarbonates and their intermediates, and dihydric alcohols are preferred from the viewpoint of producing polyurethane intermediates (polycarbonate diols). Here, from the viewpoint of producing carbonate esters with high efficiency, particularly preferred monohydric alcohols are monohydric alcohols having 4 to 10 carbon atoms. On the other hand, from the same viewpoint, particularly preferred dihydric alcohols are dihydric alcohols having 2 to 10 carbon atoms (preferably 4 to 6 carbon atoms).

[0035] The boiling point of the alcohol is over 100°C, but from the viewpoint of ease of separation of the alcohol from by-product water by distillation, it is preferably from 101 to 300°C, and more preferably from 110 to 250°C.

[0036] (Solid catalyst) As the solid catalyst, at least one selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide is used. Here, the catalyst used for the direct synthesis of carbonate esters must have an acid-base complex function. In particular, it is preferable that the catalyst has a relatively low acidity and a relatively high basicity. If the acidity is too high, a large amount of ether is synthesized rather than carbonate esters. In a moderate acid-base complex function catalyst, the alcohol dissociates and adsorbs on the base site in the form of ROM (M is the catalyst, R is a group other than "-OH" of the alcohol), forming RO-C(=O)-O...M with CO2, and on the other hand, it adsorbs on the acid site in the form of HO-R...M, and RO-C(=O)-OR is generated between the two adsorbates. As catalysts that exhibit this mechanism, cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide are suitable. In addition, since cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide are solid catalysts, there is no upper limit on the reaction temperature, and separation after the reaction is easy. For the above reasons, the solid catalyst used is at least one selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide.

[0037] An example of a method for producing cerium oxide is as follows. Cerium oxide can be produced by calcining a cerium compound (such as cerium acetylacetonate hydrate, cerium hydroxide, cerium sulfate, cerium acetate, cerium nitrate, ammonium cerium nitrate, cerium carbonate, cerium oxalate, cerium perchlorate, cerium phosphate, or cerium stearate) in an air atmosphere. Solid catalysts other than cerium oxide can be prepared in a similar manner.

[0038] When a solid catalyst of a reagent is used, the reagent may be used as it is, or a dried product obtained by drying the reagent in an air atmosphere or a calcined product obtained by calcining the reagent may be used. Alternatively, a solid catalyst can be used which is prepared by precipitating cerium from a solution, filtering, drying and calcining the precipitate.

[0039] The solid catalyst may be in the form of either a powder or a molded body. The molded solid catalyst may be formed into a sphere, pellet, cylinder, ring, wheel, granule, or other shape using only the catalyst. The molded solid catalyst may be a molded body formed by applying the solid catalyst to a support (such as a cordierite or stainless steel honeycomb).

[0040] The solid catalyst is used in a form dispersed or immobilized in a solvent. Here, immobilizing the solid catalyst in a solvent means, for example, immersing a molded body in which the solid catalyst is applied to a support body (such as a cordierite or stainless steel honeycomb) in the solvent.

[0041] If the catalytic performance deteriorates, the catalyst can be regenerated by removing it from the reactor, washing it with an alcohol such as methanol or ethanol, and then drying it in air at a temperature of about 100°C.

[0042] (solvent) The solvent is used to disperse or immobilize the solid catalyst and to dissolve the alcohol which is the reaction substrate. The solvent used is one that does not affect the reaction between carbon dioxide and alcohol. The solvent may have a boiling point of more than 100° C., and examples of the solvent include aliphatic hydrocarbons, aromatic hydrocarbons, ethers, secondary amines, and tertiary amines. Among these, from the viewpoints of not reacting with the catalyst or alcohol and of high catalyst dispersibility and boiling point, the solvent is preferably toluene, decane, dodecane, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetralin, diphenylmethane, phenylcyclohexene, or diphenyl ether. In particular, from the viewpoint of producing a carbonate ester with high efficiency, the solvent is preferably an ether solvent (a solvent having an ether bond) or a hydrophobic solvent. The solvent may be a mixture of an ether solvent and a hydrophobic solvent. Here, the hydrophobic solvent is a solvent that exhibits a solubility (g / L-H2O) of 10 g or less dissolved in 1 L of water at 25°C.

[0043] (Reaction conditions) The reaction conditions for carbon dioxide and alcohol are such that the reaction temperature is 100° C. or higher (that is, higher than the boiling point of water) and lower than the boiling points of the alcohol and the solvent. The reaction temperature depends on the boiling points of the alcohol and the solvent, but is preferably from 101 to 300°C, more preferably from 110 to 260°C, from the viewpoint of highly efficient production of a carbonate ester.

[0044] The reaction pressure may be normal pressure (1 atm) or may be pressurized. When pressurizing, a thick reactor is required, so from the viewpoint of equipment costs, the reaction pressure is preferably less than 2 MPa. Since this does not correspond to high-pressure gas equipment, the reaction pressure is more preferably less than 1 MPa.

[0045] The reaction of carbon dioxide with an alcohol is carried out, for example, by dispersing or fixing a solid catalyst as a reaction field and introducing carbon dioxide into a solvent in which an alcohol is dissolved. Carbon dioxide is preferably introduced while bubbling using, for example, a bubbling device.

[0046] For example, in a laboratory beaker scale, carbon dioxide can be blown into a beaker containing a solvent through a tube with an inner diameter of about 2 mm. A bubbler can be installed at the end of the tube. In a practical scale, a sparger can be used to promote the introduction of carbon dioxide and the flow inside the reactor.

[0047] The amounts of carbon dioxide, alcohol, catalyst, and solvent introduced are preferably adjusted appropriately according to the capacity of the reactor.

[0048] After the reaction of carbon dioxide with alcohol, each component may be separated by cooling or distillation, and may be reused in the reaction, or may be discharged as it is. Regarding carbon dioxide, a choice can be made between circulating carbon dioxide and discharging it as it is from the viewpoint of Life Cycle Assessment (LCA).

[0049] Next, the method and apparatus for producing a carbonate ester according to the present invention will be described with reference to the drawings.

[0050] [First embodiment] FIG. 1 is a schematic diagram showing a carbonic acid ester production apparatus according to the first embodiment. The carbonic acid ester production apparatus according to the first embodiment includes a reaction tower 10 in which carbon dioxide is reacted with the alcohol to produce a carbonic acid ester and by-product water, as shown in FIG. Then, in the reaction tower 10, the reaction process is carried out.

[0051] The carbonic acid ester manufacturing apparatus according to the first embodiment further includes, for example, a cooling tower 11 (an example of a first cooling tower), a distillation tower 12 (an example of a second distillation tower), a cooling tower 13, and a separation tower 14 for cooling and distilling each component discharged as a gas phase from the reaction tower 10, and separating and regenerating the components. In each tower, a cooling step (an example of a first cooling step), a distillation step (an example of a first distillation step), a cooling step, and a separation step are carried out.

[0052] The carbonic acid ester production apparatus according to the first embodiment further includes, for example, a distillation tower 21 and a separation tower 22 for distilling and cooling each component discharged as a liquid phase from the reaction tower 10 and separating and regenerating the components. In each column, a distillation step (an example of a second distillation step) and a separation step are carried out.

[0053] In FIG. 1, 100 denotes an alcohol ROH to be introduced into a reaction tower 10 . 100A denotes carbon dioxide CO2 introduced into the reaction tower 10. 100B denotes the solvent Sol to be introduced into the reaction column 10. 100C indicates the gas phase (unreacted carbon dioxide CO2, unreacted alcohol ROH, by-product water H2O and solvent Sol) discharged from the reaction tower 10. Reference numeral 101 denotes a gas phase (unreacted carbon dioxide CO2) discharged from a cooling tower 11 (an example of a first cooling tower). Reference numeral 103 denotes a liquid phase (unreacted alcohol ROH, by-product water H2O, and solvent Sol) discharged from the cooling tower 11 (an example of a first cooling tower). Reference numeral 104 denotes a gas phase (by-product water H2O) discharged from the distillation column 12 (an example of a second distillation column). Reference numeral 105 denotes a liquid phase (unreacted alcohol ROH and solvent Sol) discharged from distillation column 12 (an example of a second distillation column). Reference numeral 106 denotes the liquid phase (by-product water H2O) discharged from the cooling tower 13. Reference numeral 107 denotes the liquid phase (unreacted alcohol ROH) discharged from the separation column 14. Reference numeral 108 denotes the liquid phase (solvent Sol) discharged from the separation column 14. 201 denotes the liquid phase (carbonate C-ester, unreacted alcohol ROH, and solvent Sol) discharged from the reaction tower 10. 202 denotes a gas phase (unreacted alcohol ROH and solvent Sol) discharged from distillation column 21 (an example of a second distillation column). 203 denotes a liquid phase (carbonate ester C-ester) discharged from distillation column 21 (an example of a second distillation column). 204 denotes the liquid phase (unreacted alcohol ROH) discharged from the separation column 22. 205 denotes the liquid phase (solvent Sol) discharged from the separation column 22. Although not shown, each tower is connected by piping.

[0054] (Reaction tower 10: reaction process) In the reaction tower 10, the reaction process is carried out. In the reaction step, carbon dioxide and at least one alcohol having a boiling point of more than 100° C. and selected from the group consisting of monohydric and dihydric alcohols are supplied to a reactor 10A in which a solid catalyst as a solid catalyst and a solvent are present, and the carbon dioxide and the alcohol are reacted under conditions in which the reaction temperature is 100° C. or higher and the boiling points of the alcohol and the solvent or lower to produce a carbonate ester and by-product water.

[0055] Specifically, a solvent with a solid catalyst fixed thereto is accommodated in a reactor 10A. A liquid-phase alcohol is supplied from above to the solvent in the reactor 10A, and atmospheric pressure (gas phase) carbon dioxide is introduced from below while being bubbled. The interior of the reactor 10A is then maintained at a predetermined reaction temperature and reaction pressure. This causes the carbon dioxide and the alcohol to react with each other to produce a carbonate ester and by-product water.

[0056] The reaction tower 10 (its reactor 10A) may be, for example, any reactor such as a batch reactor, a semi-batch reactor, or a flow reactor (a continuous tank reactor, a tubular reactor, or the like).

[0057] (Cooling tower 11 (an example of a first cooling tower)) In the cooling tower 11, a cooling process (first cooling process) is carried out. The cooling step cools the unreacted carbon dioxide, unreacted alcohol (a part of the unreacted alcohol in the reactor 10A of the reaction tower 10 vaporized), by-product water (evaporated by-product water), and solvent (a part of the solvent in the reactor 10A of the reaction tower 10 vaporized) discharged as a gas phase from the reactor 10A in the reaction tower (reaction step). At this time, the unreacted alcohol, by-product water, and solvent are discharged from the reaction tower 10 on the air flow of the unreacted carbon dioxide. As a result, the mixture is separated into unreacted carbon dioxide as a gas phase and unreacted alcohol, by-product water and the solvent as a liquid phase. These components are then discharged from the cooling tower 11.

[0058] Here, the cooling temperature in the cooling tower 11 (cooling step) is set to be lower than the temperature of the unreacted alcohol, by-product water, and solvent (specifically, lower than 100° C.).

[0059] (Distillation column 12 (an example of a second distillation column)) In the distillation column 12, a distillation step (first distillation step) is carried out. In the distillation step, the unreacted alcohol, by-product water and solvent separated as liquid phases are distilled in a cooling tower 11 (cooling step). As a result, the mixture is separated into by-product water as a gas phase and unreacted alcohol and the solvent as a liquid phase, and these components are discharged from the distillation column 12.

[0060] Here, the distillation temperature in the distillation column 12 (distillation step) is set to be equal to or higher than the boiling point of the by-product water and lower than the boiling points of the unreacted alcohol and the solvent.

[0061] (Cooling tower 13) In the cooling tower 13, the cooling process is carried out. In the cooling step, the by-product water discharged in the gas phase from the distillation column 12 (distillation step) is cooled. As a result, the by-product water is liquefied. Then, the by-product water is discharged in the liquid phase from the cooling tower 13.

[0062] (separation tower 14) In the separation tower 14, for example, a distillation tower and a cooling tower are used to carry out a separation step of separating the unreacted alcohol and the solvent. In the distillation and cooling step, the unreacted alcohol and the solvent discharged as a liquid phase from the distillation column 12 (distillation step) are distilled and cooled so as to be separated and liquefied by utilizing the difference in their boiling points. This separates the unreacted alcohol and the solvent into liquid phases, which are then discharged from the distillation and cooling tower 14.

[0063] (Distillation column 21 (an example of a second distillation column)) In the distillation column 21, a distillation step (an example of a second distillation step) is carried out. In the distillation step, the carbonate ester, the unreacted alcohol, and the solvent discharged as a liquid phase from the reactor 10A in the reaction tower 10 (reaction step) are distilled. As a result, the mixture is separated into a gas phase of unreacted alcohol and solvent, and a liquid phase of carbonate ester. The unreacted alcohol and solvent are discharged from the distillation column 21, and the target carbonate ester is recovered from the distillation column 21.

[0064] Here, the distillation temperature in the distillation column 21 (distillation step) is set to be equal to or higher than the boiling points of the unreacted alcohol and the solvent and lower than the boiling point of the carbonate ester.

[0065] (Separation tower 22) In the separation tower 22, for example, a separation step is carried out by using two cooling towers to separate the unreacted alcohol and the solvent. In the separation step, for example, the unreacted alcohol and the solvent discharged as a gas phase from the distillation column 21 (distillation step) are cooled so as to be separated and liquefied by utilizing the difference in their boiling points. As a result, the mixture is separated into liquid phases, the unreacted alcohol and the solvent, and these components are discharged from the separation column 24.

[0066] (reuse) In the carbonate ester manufacturing apparatus according to the first embodiment, the unreacted carbon dioxide (gas phase) separated in the cooling tower 11 (distillation process), the unreacted alcohol and solvent separated in the separation tower 14, and the unreacted alcohol and solvent separated in the separation tower 22 are reused in the reaction tower 10 (reaction process). The unreacted alcohol and solvent separated in the distillation columns 12 and 21 (that is, a mixture of the unreacted alcohol and the solvent) may be reused as is in the reaction column 10 (reaction step) without being separated.

[0067] Through the above-mentioned process, the carbonate ester is produced in the carbonate ester production apparatus according to the first embodiment.

[0068] [Second embodiment] FIG. 2 is a schematic diagram showing a carbonic acid ester production apparatus according to the second embodiment. The carbonic acid ester production apparatus according to the second embodiment further includes a separation tower 31 and a catalyst regeneration tower 32 in the carbonic acid ester production apparatus according to the first embodiment, as shown in FIG. The carbonic acid ester production apparatus according to the second embodiment has the same configuration as the carbonic acid ester production apparatus according to the first embodiment, except that it includes a separation tower 31 and a catalyst regeneration tower 32.

[0069] In FIG. 2, 301 denotes the solid catalyst Cat discharged as a solid phase together with the liquid phase (carbonate C-ester, unreacted alcohol ROH, and solvent Sol). 302 denotes the solid catalyst Cat separated in the separation column 31 . 302 denotes the solid catalyst Cat regenerated in the catalyst regenerator 32 . Other reference symbols denote the same objects as those in Fig. 1, except that 201 denotes the liquid phase (carbonate ester C-ester, unreacted alcohol ROH, and solvent Sol) separated in separation column 31.

[0070] (Separation tower 31) In the separation column 31, a separation step is carried out. In the separation step, the solid catalyst discharged as a solid phase together with the liquid phase (carbonate ester, the unreacted alcohol, and the solvent) is separated from the liquid phase. Specifically, the solid catalyst is separated from the liquid phase using a filter etc. The separated solid catalyst is discharged from the separation tower 31 as a slurry containing the solid catalyst. Then, the liquid phase (carbonate ester, the unreacted alcohol, and the solvent) separated from the solid catalyst is discharged from the separation column 31 and sent to the distillation column 21.

[0071] (Catalyst regeneration tower 32) In the catalyst regeneration tower 32, a catalyst regeneration step is carried out. In the catalyst regeneration step, the solid catalyst separated in the separation tower 31 (separation step) is regenerated. Specifically, in the catalyst regeneration step, for example, the solid catalyst is calcined to burn off impurities and the like on the solid catalyst, thereby regenerating the solid catalyst. The calcination is carried out, for example, at 400 to 700° C. (preferably 500 to 600° C.) for about 3 hours. In order to prevent the structure of the solid catalyst from being destroyed by a sudden increase in temperature, it is preferable to dry the solid catalyst at 110° C. for about 2 hours before calcination.

[0072] (reuse) In the carbonic acid ester production apparatus according to the second embodiment, the solid catalyst regenerated in the catalyst regenerator 32 (catalyst regeneration step) is reused in the reaction tower 10 (reaction step).

[0073] [Other formats] In the carbonate ester manufacturing apparatus (or manufacturing method) according to the first and second embodiments, a form has been described in which the carbonate ester, unreacted alcohol and solvent separated as a liquid phase are distilled in the distillation column 21 (distillation process) to separate the carbonate ester into a gas phase of unreacted alcohol and solvent and a liquid phase of the carbonate ester. However, the carbonate ester production apparatus (or production method) according to this embodiment may be configured to include a cooling tower (an example of a second cooling tower) instead of the distillation tower 21, and to cool the carbonate ester, unreacted alcohol and solvent separated as a liquid phase in the distillation tower 21 (distillation process) to separate them into the unreacted alcohol and solvent as a liquid phase and the carbonate ester as a solid phase.

[0074] In this type of carbonate ester production apparatus (or production method), the carbonate ester is cooled to below its melting point to solidify, and then recovered using a filter or the like.

[0075] In the carbonate ester production apparatus (or production method) according to the first and second embodiments, a small amount of by-product water may be contained in the liquid phase components discharged from the reaction tower 10. In that case, a distillation tower (distillation step) and a cooling tower (cooling step) may be provided to separate the by-product water from the components discharged from the reaction tower 10. However, since it is difficult to separate a small amount of by-product water from the liquid phase components discharged from the reaction tower 10 and requires a large amount of energy, it is preferable not to separate the small amount of by-product water. EXAMPLES

[0076] The present invention will be described in more detail below with reference to examples, but the conditions in the examples are merely examples of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and achieve the object of the present invention.

[0077] Comparative Example 1 In a batchwise 190 mL autoclave (containing a magnetic stirrer), 0.17 g (1 mmol) of CeO2 as a solid catalyst and 10 mmol (1.2 g, 1.1 mL) of 1,6-hexanediol as an alcohol were introduced, and the air in the autoclave was purged three times with approximately 5 g of CO2. Then, CO2 (0.4 g, 9.1 mmol@130°C) was introduced into the autoclave and the pressure was increased (0.1 MPa). The temperature inside the autoclave was raised with stirring until the reaction temperature reached 130°C. The time when the reaction temperature was reached was defined as the reaction start time, and CO2 and 1,6-hexanediol were reacted for 12 hours. After that, the autoclave was cooled with water, and when it had cooled to room temperature, the pressure was reduced and 2-propanol, an internal standard substance, was added. The product was collected and analyzed by GC (gas chromatography). As a result, 0.001 mmol of chain carbonate ester was produced, and the yield of carbonate ester was 0.016%.

[0078] Example 1 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.6 g (3.5 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 80 mL (70 g) of toluene as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 110°C (the boiling point of toluene, heated to 130°C) for a reaction time of 12 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). As a result, 1.35 mmol of a dimer of a chain carbonate ester and 0.01 mmol of a trimer of a chain carbonate ester were produced, and the yield of the chain carbonate ester was 3.18%.

[0079] Example 2 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.6 g (3.5 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 80 mL (70 g) of toluene as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 110°C (the boiling point of toluene, heated to 130°C) for a reaction time of 48 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). As a result, 2.68 mmol of a dimer of the chain carbonate ester and 0.02 mmol of a trimer of the chain carbonate ester were produced, and the yield of the chain carbonate ester was 6.31%.

[0080] Example 3 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 30 mL (No. 1), 80 mL (No. 2), or 110 mL (No. 3) of toluene as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 110°C (the boiling point of toluene, heated to 130°C) for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 1. From the results in Table 1, it was found that the yield of carbonate ester was 1.6 to 1.7%, and the amount of solvent had no effect. [Table 1]

[0081] Comparative Example 2 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst and 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 130°C for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). As a result, the reaction substrate 1,6-hexanediol solidified and the yield of carbonate ester was 0%, indicating that a solvent is necessary for the production of carbonate ester.

[0082] Example 4 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 30 mL of n-decane as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 110°C (No. 1), 140°C (No. 2), 150°C (No. 3), or 170°C (No. 4) for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 2. It can be seen from the results in Table 2 that the higher the reaction temperature, the higher the yield of carbonate ester.

[0083] [Table 2]

[0084] Example 5 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 30 mL of n-decane as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 140°C (No. 1) or 150°C (No. 2) for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 3. It can be seen from the results in Table 3 that the yield of carbonate ester is improved by extending the reaction time.

[0085] [Table 3]

[0086] Example 6 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 30 mL of n-dodecane as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 140°C (No. 1), 150°C (No. 2), or 170°C for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 4. From the results in Table 4, it can be seen that the yield of carbonate ester is improved by further increasing the reaction temperature.

[0087] [Table 4]

[0088] Example 7 Into a 200 mL flow-through eggplant-shaped flask (top cooling temperature 4°C), 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 30 mL of a solvent shown in Table 5 were introduced. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 150°C for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 5. From the results in Table 5, it can be seen that the dispersibility of the solid catalyst in the solvent was low, and the yield of the carbonate ester decreased.

[0089] [Table 5]

[0090] Example 8 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was introduced 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 1 mL (No. 1), 5 mL (No. 2), or 30 mL (No. 3) of diethylene glycol diethyl ether as a solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 170°C for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 6. From the results in Table 6, it can be seen that the yield of carbonate ester is improved by using diethylene glycol diethyl ether as a solvent. However, it can also be seen that if the amount of solvent is too large, the dispersibility of the solid catalyst deteriorates and the yield decreases.

[0091] [Table 6]

[0092] Example 9 Into a 200 mL round-bottom flask (with upper cooling temperature of 4°C) were placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol (10 g, 9 mL) of 1,6-hexanediol as an alcohol, and 5 mL of diethylene glycol diethyl ether as a solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 170°C for a reaction time of 48 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). As a result, 7.3 mmol of a dimer of a chain carbonate ester and 0.14 mmol of a trimer of a chain carbonate ester were produced, and the yield of the chain carbonate ester was 18%. It can be seen that the yield of carbonate ester is further improved by using diethylene glycol diethyl ether as a solvent and carrying out the reaction for a long period of time.

[0093] Example 10 Into a 200 mL flow-through eggplant-shaped flask (top cooling temperature 4°C), 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol of an alcohol shown in Table 7, and 5 mL of diethylene glycol diethyl ether as a solvent were placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with each alcohol at a reaction temperature of 150°C for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 7. From the results in Table 7, it is understood that when a dihydric alcohol having 2 to 10 carbon atoms is used as the alcohol, a carbonate ester can be produced with high efficiency.

[0094] [Table 7]

[0095] Example 11 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) were placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol of 1,10-decanediol, and 10 mL of diethylbenzene as a solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 and 1,10-decanediol were reacted at a reaction temperature of 150°C for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). As a result, the yield of chain carbonate was 3.4%.

[0096] Comparative Example 3 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst and 85 mmol (10 g, 9 mL) of propylene glycol. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 and propylene glycol were reacted at a reaction temperature of 150°C for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). As a result, because no solvent was used, the reaction between CO2 and propylene glycol did not proceed, and the yield of carbonate ester was 0%.

[0097] Example 12 Into a 200 mL flow-through eggplant-shaped flask (top cooling temperature 4°C), 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol of an alcohol shown in Table 8, and 5 mL of diethylene glycol diethyl ether as a solvent were placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with each alcohol at the reaction temperature shown in Table 8 for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 8. It is apparent from the results in Table 8 that when a monohydric alcohol having a boiling point of more than 100° C. and 4 to 10 carbon atoms is used as the alcohol, a carbonate ester can be produced with high efficiency.

[0098] [Table 8]

[0099] Comparative Example 4 Into a 200 mL flow-through eggplant-shaped flask (top cooling temperature 4°C), 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol of an alcohol shown in Table 9, and 5 mL of diethylene glycol diethyl ether as a solvent were placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with each alcohol at the reaction temperature and reaction time shown in Table 9. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 9. From the results in Table 9, it can be seen that when a monohydric alcohol with a boiling point of 100°C or less is used as the alcohol, the reaction temperature cannot be increased because the boiling point is below 100°C, and therefore a carbonate ester cannot be produced.

[0100] [Table 9]

[0101] Comparative Example 5 Into a 200 mL round-bottom flask (cooling temperature at the top: 4°C) were placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 85 mmol of glycerin, and 5 mL of diethylene glycol diethyl ether as a solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 and glycerin were reacted at the reaction temperature shown in Table 10 for a reaction time of 20 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 10. From the results in Table 10, it can be seen that when glycerin, which is a trihydric alcohol, is used, carbonate ester cannot be produced even if the reaction temperature is increased, because glycerin is not soluble in the solvent.

[0102] [Table 10]

[0103] Example 13 Into a 50 mL round-bottom flask (with upper cooling temperature of 4° C.) of a flow system, 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 34 mmol of 1,6-hexanediol, and 5 mL of a solvent shown in Table 11 were placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 170°C for a reaction time of 24 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 11. The results in Table 11 show that the use of a solvent having a boiling point of over 100° C., particularly an ether solvent, makes it possible to produce carbonate esters with high efficiency.

[0104] [Table 11]

[0105] Example 14 Into a 50 mL flow-through eggplant-shaped flask (top cooling temperature 20° C.), 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 34 mmol of 1,6-hexanediol, and 5 g of a solvent shown in Table 12 were placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 190°C for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 12. The results in Table 12 show that the use of a solvent having a boiling point of over 100° C., particularly an ether solvent, makes it possible to produce carbonate esters with high efficiency.

[0106] [Table 12]

[0107] Example 15 Into a 50 mL flow-type eggplant-shaped flask (top cooling temperature 24°C), 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, and 3 g of a solvent shown in Table 13 together with its solubility in water were placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 200°C for a reaction time of 1 h. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 13. The results in Table 13 show that carbonate esters can be produced with high efficiency when a solvent having a boiling point of over 100° C., particularly an ether solvent or a hydrophobic solvent, is used.

[0108] [Table 13]

[0109] (Example 16) Into a 50 mL flow-through eggplant-shaped flask (top cooling temperature 24°C), 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, 2 g of triethylene glycol dimethyl ether as a first solvent, and 3 g of each of the solvents shown in Table 14 as a second solvent were introduced. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 200°C for a reaction time of 1 h. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 14. From the results in Table 14, it is clear that carbonate esters can be produced with high efficiency even when a mixture of an ether solvent and a hydrophobic solvent is used in a solvent having a boiling point of over 100°C.

[0110] [Table 14]

[0111] (Example 17) Into a 50 mL flow-through eggplant-shaped flask (top cooling temperature 24°C), 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, 1 to 4 g of triethylene glycol dimethyl ether as a first solvent, and 3 g of diphenyl ether as a second solvent shown in Table 15 were introduced. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 200°C for a reaction time of 1 h. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 15. From the results in Table 15, it can be seen that carbonate esters can be produced with high efficiency even when a mixture of hydrophilic and hydrophobic solvents is used among ether-based solvents with a boiling point of over 100°C.

[0112] [Table 15]

[0113] (Example 18) Into a 50 mL flow-through eggplant-shaped flask (top cooling temperature 24°C), 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, 2 g of triethylene glycol dimethyl ether as a first solvent, and 1 to 5 g of diphenyl ether as a second solvent shown in Table 16 were introduced. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 200°C for a reaction time of 1 h. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 16. From the results in Table 16, it can be seen that carbonate esters can be produced with high efficiency even when a mixture of hydrophilic and hydrophobic solvents is used among ether-based solvents with a boiling point of over 100°C.

[0114] [Table 16]

[0115] (Example 19) Into a 50 mL flow-type eggplant-shaped flask (top cooling temperature 24°C), 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of each of the alcohols shown in Table 17, 2 g of triethylene glycol dimethyl ether as a first solvent, and 3 g of diphenyl ether as a second solvent were introduced. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with various alcohols at the reaction temperature shown in Table 17 for a reaction time of 48 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 17. From the results in Table 17, it can be seen that carbonate esters can be produced with high efficiency by using a mixture of hydrophilic and hydrophobic solvents among ether-based solvents with a boiling point of over 100°C, and using a dihydric alcohol having 3 to 10 carbon atoms or a monohydric alcohol having 8 to 10 carbon atoms as the alcohol with a boiling point of 100°C or higher.

[0116] [Table 17]

[0117] (Example 20) In a 50 mL round-bottom flask (cooling temperature at the top: 24°C) were placed 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, 2 g of triethylene glycol dimethyl ether as a first solvent, and 3 g of diphenyl ether as a second solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 and 1,6-hexanediol were reacted at the reaction temperature shown in Table 18 for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 18. From the results in Table 18, it can be seen that when triethylene glycol dimethyl ether and diphenyl ether are used as a solvent having a boiling point of more than 100°C, carbonate ester can be produced with high efficiency at a reaction temperature of 180 to 215°C.

[0118] [Table 18]

[0119] Example 21 In a flow-through type 50 mL eggplant-shaped flask (cooling temperature at the top: 20°C), CeO2 (No. 1), ZrO2 (No. 2), La2O3 (No. 3), Sm2O3 (No. 4), and Pr6O 11 (No. 5), SnO2 (No. 6), Dy2O3 (No. 7), Gd2O3 (No. 8), and Eu2O3 (No. 9) were added in an amount of 0.4 g, 1,6-hexanediol: 34 mmol, and diphenyl ether: 5 g as a solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 190°C for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 19. From the results in Table 19, ZrO2 (No. 2), La2O3 (No. 3), Sm2O3 (No. 4), Pr6O 11 It can be seen that carbonate esters can be produced with high efficiency even when using solid catalysts such as SnO2 (No. 5), SnO2 (No. 6), Dy2O3 (No. 7), Gd2O3 (No. 8), and Eu2O3 (No. 9).

[0120] [Table 19]

[0121] Comparative Example 6 The reaction was carried out under the same conditions as in Example 14, except that 0.4 g of each of the catalysts shown in Table 20 was used as the solid catalyst. The results are shown in Table 20. From the results in Table 20, it can be seen that when SiO2 (No. 1), SiO2-Al2O3 (No. 2), γ-Al2O3 (No. 3), MgO (No. 4), TiO2 (No. 5), HfO2 (No. 6), Y2O3 (No. 7), and ZnO (No. 8) were used as solid catalysts, the reactivity was low or there was almost no reaction.

[0122] [Table 20]

[0123] Example 22 Into a 50 mL round-bottom flask (cooling temperature at the top: 20°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 34 mmol of 1,6-hexanediol, and 1 g (No. 1), 3 g (No. 2), 5 g (No. 3, the same as No. 1 in Example 14), 7 g (No. 4), and 10 g (No. 5) of diphenyl ether as a solvent. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 190°C for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 21. It can be seen from the results in Table 21 that the amount of diphenyl ether used as a solvent does not significantly affect the yield of carbonate ester, and any amount of diphenyl ether makes it possible to produce carbonate ester with high efficiency.

[0124] [Table 21]

[0125] Comparative Example 7 In a 50 mL round-bottom flask (cooling temperature at the top: 20°C) was placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst and 34 mmol of 1,6-hexanediol, but no solvent (0 g) was placed. Thereafter, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at a reaction temperature of 190°C for a reaction time of 4 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). When no solvent was used, the yield of carbonate ester was 3.8%. However, 1,6-hexanediol and the produced carbonate ester adhered to the cooling part at the top of the flask and solidified, blocking the flow paths for CO2 and by-product water, making it difficult to continue the reaction, so it was found that a solvent was essential.

[0126] Example 23 In a 50 mL round-bottom flask (cooling temperature at the top: 20°C) were placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 34 mmol of 1,6-hexanediol, and 5 g of diphenyl ether as a solvent. Then, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and the CO2 was reacted with 1,6-hexanediol at reaction temperatures of 110°C (No. 1), 150°C (No. 2), 170°C (No. 3), 190°C (No. 4), or 210°C (No. 5) for a reaction time of 16 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 22. It can be seen from the results in Table 22 that the higher the reaction temperature, the higher the yield of carbonate ester.

[0127] [Table 22]

[0128] Example 24 In a 50 mL round-bottom flask (cooling temperature at the top: 20°C) were placed 0.4 g (2.3 mmol) of CeO2 as a solid catalyst, 34 mmol of 1,6-hexanediol, and 5 g of diphenyl ether as a solvent. Thereafter, CO2 was introduced into the flask while bubbling at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and CO2 was reacted with 1,6-hexanediol at a reaction temperature of 190°C for a reaction time of 16 to 480 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 23. From the results in Table 23, it can be seen that the yield of carbonate ester increases with increasing reaction time.

[0129] [Table 23]

[0130] (Example 25) In a 50 mL round-bottom flask (cooling temperature at the top: 24°C) were placed 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, 2 g of triethylene glycol dimethyl ether as a first solvent, and 3 g of diphenyl ether as a second solvent. Thereafter, CO2 was introduced into the flask while bubbling at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and CO2 was reacted with 1,6-hexanediol at a reaction temperature of 210°C for a reaction time of 4 to 96 hours. The flask was then air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 24. From the results in Table 24, it can be seen that the yield of carbonate ester increases with increasing reaction time. It can also be seen that the average molecular weight of the product can be increased.

[0131] [Table 24]

[0132] (Example 26) In a 50 mL round-bottom flask (cooling temperature at the top: 24°C) were placed 0.1 g (0.6 mmol) of CeO2 as a solid catalyst, 17 mmol of 1,6-hexanediol, 2 g of triethylene glycol dimethyl ether as a first solvent, and 3 g of diphenyl ether as a second solvent. After that, CO2 was bubbled into the flask at a pressure of 0.1 MPa and a flow rate of 200 mL / min, and reacted with 1,6-hexanediol at a reaction temperature of 210°C for 4 hours. After washing the catalyst after the reaction with ethanol, a regeneration step was performed in which the catalyst was dried at 110°C for 12 hours, and the reaction was repeated for the number of reactions shown in Table 25. After each reaction, the flask was air-cooled, and when it had cooled to room temperature, the product was collected and analyzed by GC (gas chromatography). The results are shown in Table 25. The results in Table 25 show that the catalyst can be regenerated and used repeatedly to maintain its activity.

[0133] [Table 25]

[0134] From the above, it is understood that in this embodiment, a carbonate ester can be produced highly efficiently under a moderate reaction pressure while removing by-product water from the reaction field without using a dehydrating agent or a chemical hydrating agent. [Explanation of symbols]

[0135] 10. Reaction tower 11 Cooling tower (an example of the first cooling tower) 12 Distillation tower (an example of a first distillation tower) 13 Cooling Tower 14 Separation tower 21 Distillation tower (an example of a first distillation tower) 22 Separation tower

Claims

1. A method for producing a carbonate ester, comprising reacting carbon dioxide with at least one alcohol having a boiling point of more than 100°C, and selected from the group consisting of monohydric alcohols having 4 to 10 carbon atoms and dihydric alcohols having 2 to 10 carbon atoms, in the presence of at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide, and a solvent, under conditions where the reaction temperature is 100°C or higher and is lower than the boiling points of the alcohol and the solvent, to produce a carbonate ester and by-product water, and removing the by-product water from a reaction site by evaporation.

2. 2. The method for producing a carbonate ester according to claim 1, wherein the alcohol is a dihydric alcohol having 2 to 10 carbon atoms.

3. 3. The method for producing a carbonate ester according to claim 2, wherein the dihydric alcohol is a dihydric alcohol having 4 to 6 carbon atoms.

4. The method for producing a carbonate ester according to any one of claims 1 to 3, wherein the evaporated by-product water is removed from the reaction field by a gas stream of carbon dioxide.

5. A method for producing a carbonate ester described in any one of claims 1 to 4, wherein the pressure during the reaction is 0.1 MPa or more and less than 1 MPa.

6. The method for producing a carbonate ester according to any one of claims 1 to 5, wherein the solvent is an ether-based solvent.

7. The method for producing a carbonate ester according to any one of claims 1 to 6, wherein the solvent is a hydrophobic solvent.

8. a reaction step of supplying carbon dioxide and at least one alcohol having a boiling point of more than 100° C. and selected from the group consisting of monohydric alcohols having 4 to 10 carbon atoms and dihydric alcohols having 2 to 10 carbon atoms to a reactor in which at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide and a solvent are present, and reacting the carbon dioxide with the alcohol under conditions of a reaction temperature of 100° C. or more and the boiling points of the alcohol and the solvent or less to produce a carbonate ester and by-product water; A first cooling step in which the unreacted carbon dioxide, the unreacted alcohol, the by-product water and the solvent discharged as a gas phase from the reactor in the reaction step are cooled to separate the unreacted carbon dioxide as a gas phase and the unreacted alcohol, the by-product water and the solvent as a liquid phase; A first distillation step in which the unreacted alcohol, the by-product water, and the solvent separated as a liquid phase in the first cooling step are separated by distillation into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase; a second distillation step in which the carbonate ester, the unreacted alcohol, and the solvent discharged as a liquid phase from the reactor in the reaction step are distilled to separate the unreacted alcohol and the solvent as a gas phase and the carbonate ester as a liquid phase, or a second cooling step in which the carbonate ester, the unreacted alcohol, and the solvent discharged as a liquid phase from the reactor in the reaction step are cooled to separate the unreacted alcohol and the solvent as a liquid phase and the carbonate ester as a solid phase; having The unreacted carbon dioxide separated in the first cooling step, the unreacted alcohol and the solvent separated in the first distillation step, and the unreacted alcohol and the solvent separated in the second distillation step or the second cooling step are reused in the reaction step. A method for producing carbonate esters.

9. a separation step of separating a solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction step from the liquid phase; a catalyst regeneration step of regenerating the solid catalyst separated in the separation step; and The method for producing a carbonate ester according to claim 8, wherein the solid catalyst regenerated in the catalyst regeneration step is reused in the reaction step.

10. a reaction tower having a reactor in which at least one solid catalyst selected from the group consisting of cerium oxide, zirconium oxide, lanthanum oxide, samarium oxide, praseodymium oxide, tin oxide, dysprosium oxide, gadolinium oxide, and europium oxide and a solvent are present, in which carbon dioxide and at least one alcohol having a boiling point of more than 100° C. and selected from the group consisting of monohydric alcohols having 4 to 10 carbon atoms and dihydric alcohols having 2 to 10 carbon atoms are supplied to the reactor, and the carbon dioxide and the alcohol are reacted under conditions of a reaction temperature of 100° C. or higher and not higher than the boiling points of the alcohol and the solvent to produce a carbonate ester and by-product water; A first cooling tower that cools the unreacted carbon dioxide, the unreacted alcohol, the by-product water, and the solvent discharged as a gas phase from the reactor in the reaction tower and separates them into the unreacted carbon dioxide as a gas phase and the unreacted alcohol, the by-product water, and the solvent as a liquid phase; A first distillation tower that separates the unreacted alcohol, the by-product water, and the solvent separated as a liquid phase in the first cooling tower by distillation into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase; a second distillation tower which distills the carbonate ester, the unreacted alcohol and the solvent discharged as a liquid phase from the reactor in the reaction tower, and separates them into the unreacted alcohol and the solvent as a gas phase and the carbonate ester as a liquid phase, or a second cooling tower which cools the carbonate ester, the unreacted alcohol and the solvent discharged as a liquid phase from the reactor in the reaction tower, and separates them into the unreacted alcohol and the solvent as a liquid phase and the carbonate ester as a solid phase; Equipped with The unreacted carbon dioxide separated in the first cooling tower, the unreacted alcohol and the solvent separated in the first distillation tower, and the unreacted alcohol and the solvent separated in the second distillation tower or the second cooling tower are reused in the reaction tower. Carbonate ester manufacturing equipment.

11. a separation tower for separating a solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction tower from the liquid phase; a catalyst regeneration tower for regenerating the solid catalyst separated in the separation tower; Further equipped with 11. The apparatus for producing a carbonate ester according to claim 10, wherein the solid catalyst regenerated in the catalyst regeneration tower is reused in the reaction tower.

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