Catalyst for carbonate ester production, method for producing a carbonate ester catalyst, method for producing carbonate ester, and apparatus for producing carbonate ester

Abstract

To provide a catalyst for producing carbonate esters that can produce carbonate esters with high efficiency using cerium oxide, a method for producing the same, and a method for producing carbonate esters using the catalyst and an apparatus for producing carbonate esters. [Solution] A catalyst for producing carbonate esters using carbon dioxide and alcohol as raw materials, comprising a catalyst carrier mainly composed of cerium oxide and barium or strontium supported on the catalyst carrier, wherein the amount of barium supported relative to the cerium oxide is 0.20 to 6.00 mol%, and the amount of strontium supported relative to the cerium oxide is 0.25 to 3.00 mol%, and a method for producing the same, as well as a method for producing carbonate esters using the catalyst and an apparatus for producing carbonate esters.

Description

Technical Field

[0004] , , ,

[0001] The present disclosure relates to a catalyst for producing a carbonate ester, a method for producing the catalyst for producing a carbonate ester, a method for producing a carbonate ester, and an apparatus for producing a carbonate ester.

Background Art

[0002] A carbonate ester is a general term for compounds in which one or two hydrogen atoms of the two hydrogen atoms of carbonic acid HO—C(═O)—OH are substituted with an alkyl group or an aryl group, and has a structure of RO—C(═O)—OR′ (R and R′ represent a saturated hydrocarbon group or an unsaturated hydrocarbon group).

[0003] Carbonate esters are used as additives such as gasoline additives for improving octane number and diesel fuel additives for reducing particles in exhaust gas. In addition, they are used as alkylating agents, carbonylating agents, solvents, etc. when synthesizing resins and organic compounds such as polycarbonates, polyurethanes, pharmaceuticals, and agricultural chemicals. They are also used as raw materials for electrolytes of lithium batteries, lubricant raw materials, and raw materials for oxygen scavengers for rust prevention of boiler pipes. They are very useful compounds.

[0004] Conventional methods for producing carbonate esters primarily involve directly reacting phosgene with alcohol using phosgene as the carbonyl source. This method uses phosgene, which is extremely toxic and corrosive, requiring meticulous handling during transportation and storage, and incurring significant costs for maintaining and ensuring the safety of the manufacturing facilities. Furthermore, this method involves the presence of halogens such as chlorine in the raw materials and catalysts, resulting in trace amounts of halogens in the obtained carbonate ester that cannot be removed by simple purification processes. For applications such as gasoline additives, diesel fuel additives, and electronic materials, there are concerns about corrosion, making thorough purification processes essential to reduce the amount of halogens to an extremely small level. Moreover, due to the use of phosgene, which is extremely harmful to human health, administrative guidance has become stricter, including the denial of permission for the construction of new manufacturing facilities using this method, and there is a strong demand for new manufacturing methods that do not use phosgene.

[0005] In this context, for example, Patent Document 1 describes "a method for producing carbonate esters, comprising reacting carbon dioxide with at least one alcohol selected from the group consisting of monovalent and divalent alcohols having a boiling point above 100°C 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 below the boiling points of the alcohol and the solvent, thereby producing carbonate esters and by-product water, and removing the by-product water from the reaction site by evaporation." [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-151986 [Overview of the project] [Problems that the invention aims to solve]

[0007] The method for producing carbonate esters described in Patent Document 1 is an excellent method that allows for the efficient production of carbonate esters under mild reaction pressure, without the use of dehydrating agents or chemical hydrating agents, while removing by-product water from the reaction site.

[0008] In the method for producing carbonate esters described in Patent Document 1, cerium oxide, in particular, as a solid catalyst, is a metal oxide that exhibits specific activity in the synthesis reaction of carbonate esters using carbon dioxide and alcohol as raw materials. Therefore, there is a desire to further enhance the activity of cerium oxide as a solid catalyst and improve the yield of carbonate esters.

[0009] Therefore, the object of this disclosure is to provide a catalyst for producing carbonate esters that can produce carbonate esters with high efficiency using cerium oxide, a method for producing the same, a method for producing carbonate esters using the catalyst, and an apparatus for producing carbonate esters. [Means for solving the problem]

[0010] The means of solving the problem include the following aspects: <1> The catalyst carrier mainly composed of cerium oxide and barium or strontium supported on the catalyst carrier, The amount of barium supported on the cerium oxide is 0.20 to 6.00 mol%, The amount of strontium supported on the cerium oxide is 0.25 to 3.00 mol%. A catalyst for producing carbonate esters using carbon dioxide and alcohol as raw materials. <2> The aforementioned alcohol is a dihydric alcohol. <1> A catalyst for the production of carbonate esters as described above. <3> The carbonate ester is a polycarbonate diol. <1> or <2> A catalyst for the production of carbonate esters as described above. <4> <1> ~ <3> A method for producing a catalyst for carbonate ester according to any one of the items, An impregnation and support step in which a barium compound or a strontium compound is impregnated and supported on the catalyst support, A calcination step to produce a catalyst by calcining the catalyst support after the impregnation and loading step, Having, A method for producing a catalyst for carbonate ester production using carbon dioxide and alcohol as raw materials. <5> The firing temperature in the aforementioned firing process is 350 to 800°C. <4> A method for producing a catalyst for carbonate ester production as described above. <6> <1> ~ <3> A method for producing carbonate esters, comprising reacting carbon dioxide with at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point above 100°C in the presence of a solid catalyst comprising a catalyst for producing carbonate esters as described in any one of the above items and a solvent, under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and the solvent, thereby producing carbonate esters and by-product water, and removing the by-product water from the reaction site by evaporation. <7> The evaporated by-product water is removed from the reaction field by a stream of carbon dioxide. <6> A method for producing carbonate esters as described above. <8> The alcohol is a monohydric alcohol having 4 to 10 carbon atoms. <6> or <7> A method for producing carbonate esters as described above. <9> The alcohol is a divalent alcohol having 2 to 10 carbon atoms. <6> or <7> A method for producing carbonate esters as described above. <10> The aforementioned divalent alcohol is a divalent alcohol having 4 to 6 carbon atoms. <9> A method for producing carbonate esters as described above. <11> The solvent is a solvent that contains one or more selected from the group consisting of toluene, decane, dodecane, and ether-based solvents. <6> ~ <10> A method for producing a carbonate ester according to any one of the items. <12> <1> ~ <3> A reaction step comprising: supplying carbon dioxide and at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point greater than 100°C to a reactor containing a solid catalyst consisting of a catalyst for producing carbonate esters as described in any one of the items and a solvent, and reacting the carbon dioxide and the alcohol under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and the solvent to produce carbonate esters and by-product water; A first cooling step involves cooling the unreacted carbon dioxide, unreacted alcohol, by-product water, and solvent discharged as a gas phase from the reactor in the reaction step, thereby separating them into a gas phase of unreacted carbon dioxide and a liquid phase of unreacted alcohol, by-product water, and solvent. A first distillation step is performed to separate the unreacted alcohol, the by-product water, and the solvent, which have been separated as a liquid phase in the first cooling step, into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase by distillation. A second distillation step in which the carbonate ester, unreacted alcohol, and solvent discharged as a liquid phase from the reactor in the reaction step are distilled to separate them into a gas phase consisting of the unreacted alcohol and solvent and a liquid phase consisting of the carbonate ester, or a second cooling step in which the carbonate ester, unreacted alcohol, and solvent discharged as a liquid phase from the reactor in the reaction step are cooled to separate them into a liquid phase consisting of the unreacted alcohol and solvent and a solid phase consisting of the carbonate ester, It has, The unreacted carbon dioxide separated in the first cooling step, the unreacted alcohol and solvent separated in the first distillation step, and the unreacted alcohol and solvent separated in the second distillation step or the second cooling step are reused in the reaction step. A method for producing carbonate esters. <13> A separation step is performed to separate the solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction step, A catalyst regeneration step for regenerating the solid catalyst separated in the separation step, further comprising, The method for producing a carbonic ester according to <12>, wherein the solid catalyst regenerated in the catalyst regeneration step is reused in the reaction step. <14> Having a reactor in which a solid catalyst composed of a catalyst for producing a carbonic ester according to any one of <1> to <3> and a solvent are present, and supplying carbon dioxide and at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point exceeding 100°C to the reactor, and reacting the carbon dioxide and the alcohol under the conditions that the reaction temperature is 100°C or higher and lower than the boiling points of the alcohol and the solvent to produce a carbonic ester and by-product water, Cooling the unreacted carbon dioxide, unreacted alcohol, by-product water and solvent discharged as a gas phase from the reactor in the reaction tower, and separating them into unreacted carbon dioxide as a gas phase and unreacted alcohol, by-product water and solvent as a liquid phase, a first cooling tower, In the first cooling tower, the unreacted alcohol, by-product water and solvent separated as a liquid phase are separated by distillation into by-product water as a gas phase and unreacted alcohol and solvent as a liquid phase, a first distillation tower, Distilling the carbonic ester, unreacted alcohol and solvent discharged as a liquid phase from the reactor in the reaction tower into unreacted alcohol and solvent as a gas phase and carbonic ester as a liquid phase, a second distillation tower, or cooling the carbonic ester, unreacted alcohol and solvent discharged as a liquid phase from the reactor in the reaction tower to separate them into unreacted alcohol and solvent as a liquid phase and carbonic ester as a solid phase, a second cooling tower, comprising, 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 production apparatus. <15> A separation tower that separates 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 that regenerates the solid catalyst separated by the separation tower. Further comprising The carbonate production apparatus according to <14>, wherein the solid catalyst regenerated in the catalyst regeneration tower is reused in the reaction tower.

Advantages of the Invention

[0011] According to the present disclosure, it is possible to provide a catalyst for producing a carbonate using cerium oxide, which can produce a carbonate with high efficiency, a method for producing the same, a method for producing a carbonate using the same, and a carbonate production apparatus.

Brief Description of the Drawings

[0012] [Figure 1] It is a schematic configuration diagram showing a carbonate production apparatus according to the first embodiment. [Figure 2] It is a schematic configuration diagram showing a carbonate production apparatus according to the second embodiment.

Modes for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described. In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. In a numerical range described step by step, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Within a numerical range, the upper or lower limit stated within that range may be replaced with the value shown in the example. The term "process" includes not only independent processes, but also any process that cannot be clearly distinguished from other processes, as long as its intended purpose is achieved. A "combination of preferred embodiments" is a more preferred embodiment.

[0014] <Catalyst for carbonate ester production> The catalyst for carbonate ester production described herein is a catalyst for carbonate ester production (hereinafter also simply referred to as "catalyst") that uses carbon dioxide and alcohol as raw materials. The catalyst of this disclosure comprises a catalyst support mainly composed of cerium oxide and barium or strontium supported on the catalyst support. Furthermore, the amount of barium supported relative to cerium oxide is 0.20–6.00 mol%. Furthermore, the amount of strontium supported on cerium oxide is between 0.25 and 3.00 mol%.

[0015] The catalyst disclosed herein is a cerium oxide-based catalyst capable of producing carbonate esters with high efficiency. The catalyst disclosed herein was discovered based on the following findings. The main reason for the low reactivity of carbon dioxide and alcohol is that the solubility of carbon dioxide in the reaction solution is low, and the supply of carbon dioxide to cerium oxide becomes the rate-limiting factor. Therefore, improving the amount and strength of carbon dioxide adsorption on the cerium oxide surface will increase the reactivity of carbon dioxide with alcohol. Therefore, the inventors investigated controlling the surface properties of cerium oxide by supporting a secondary metal species on cerium oxide. As a result, the inventors obtained the following findings. Since carbon dioxide is weakly acidic, barium and strontium are effective as secondary metal species because they are expected to improve basicity. This improves the amount and strength of carbon dioxide adsorption on the cerium oxide surface, enabling the efficient production of carbonate esters.

[0016] Based on the above findings, the catalyst of this disclosure was discovered.

[0017] The following describes the details of the catalyst in this disclosure.

[0018] (Catalyst support) The catalyst support is a catalyst mainly composed of cerium oxide (CeO2). The catalyst support may contain impurities. A catalyst mainly composed of cerium oxide is one in which the cerium oxide content relative to the catalyst support is 70% by mass or more (preferably 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more). The catalyst may contain small amounts of impurities other than cerium oxide that are present in the manufacturing process of the catalyst support. The cerium oxide content is the mass of cerium oxide relative to the total mass of impurities and cerium oxide. The method for measuring the cerium oxide content in the catalyst support is to perform pretreatment such as acid decomposition or alkali melting, followed by measurement using the ICP-AES method. Furthermore, to analyze the catalyst and determine the cerium oxide content, it is effective to analyze the cross-section of the catalyst support using a scanning electron microscope (SEM-EDX) or a transmission electron microscope (TEM-EDX) attached to an energy-dispersive X-ray analyzer. When measuring the cerium oxide content of a catalyst supported with barium and strontium, it is best to perform the component analysis in a region where co-catalyst components such as barium and strontium are absent. Although there is some variability due to the localized analysis of the field of view in SEM and TEM, the average value of 10 component analysis values ​​is used to determine the cerium oxide content in the catalyst support.

[0019] Cerium oxide has the properties of being relatively low in acidity and relatively high in basicity. If the acidity is too high, it will synthesize a large amount of ether rather than carbonate ester. In a moderately acid-base complex functional catalyst, it is conceivable that alcohols dissociate and adsorb at the basic site in the form of ROM (M is the catalyst, R is a group of the alcohol other than "-OH"), forming RO-C(=O)-O...M with CO2, while on the other hand, they adsorb at the acid site in the form of HO-R...M, generating RO-C(=O)-OR between the two adsorbed species. Cerium oxide is a catalyst that exhibits this mechanism.

[0020] (Assistant catalyst) The catalyst support contains barium or strontium as a co-catalyst. The barium or strontium is included in the catalyst support, for example, in the form of an oxide (barium oxide or strontium oxide).

[0021] The amount of barium supported on cerium oxide is 0.20 to 6.00 mol%, preferably 0.24 to 2.00 mol%, and more preferably 0.36 to 1.20 mol%. The amount of strontium supported on cerium oxide is 0.25 to 3.00 mol%, preferably 0.30 to 2.00 mol%, and more preferably 0.4 to 1.00 mol%. When the supported amounts of barium and strontium are within the above range, the adsorption amount and adsorption strength of carbon dioxide are improved, and carbonate esters can be produced with high efficiency.

[0022] The quantitative determination of the amount of barium and strontium supported in the catalyst is performed by measuring the amount using the ICP-AES method after pretreatment of the catalyst, such as acid decomposition or alkali melting.

[0023] The catalyst of this disclosure may be in the form of a powder or a molded body. The catalyst in the molded body may be a molded body consisting only of the catalyst, molded into a spherical, pelletized, cylindrical, ring-shaped, wheel-shaped, granular shape, or the like. Alternatively, the catalyst in the molded body may be a molded body in which the catalyst is coated onto a support (such as a honeycomb made of cordierite or stainless steel).

[0024] The catalyst of this disclosure is a catalyst for producing carbonate esters using carbon dioxide and an alcohol as raw materials, wherein a dihydric alcohol is preferred as the alcohol. Furthermore, a polycarbonate diol is preferred as the resulting polycarbonate. Further details regarding the raw materials used will be explained in detail in the method for producing carbonate esters described herein.

[0025] <Method for producing catalysts for carbonate ester production> The method for producing a carbonate ester catalyst according to this disclosure is a method for producing a carbonate ester catalyst according to this disclosure, using carbon dioxide and alcohol as raw materials. The method for producing the catalyst disclosed herein is: An impregnation and support step in which a barium compound or a strontium compound is impregnated and supported on a catalyst support, A calcination process in which the catalyst support after the impregnation and loading process is calcined to produce the catalyst, It has.

[0026] (Impregnation and loading process) In the impregnation and loading process, a barium compound or a strontium compound is impregnated and loaded onto the catalyst support. Specifically, for example, in the impregnation and loading process, a catalyst support is impregnated with a solution in which a barium compound or a strontium compound is dissolved in a solvent, thereby loading the barium compound or strontium compound onto the catalyst support.

[0027] Examples of barium compounds include barium nitrate, barium hydroxide, barium acetate, barium carbonate, barium chloride, and barium perchlorate. Examples of strontium compounds include strontium nitrate, strontium hydroxide, strontium acetate, strontium carbonate, strontium chloride, and strontium perchlorate. The solvent is not particularly limited as long as it can dissolve barium compounds and strontium compounds. For example, water and alcohols (methanol, ethanol, etc.) are preferred solvents, and water is more preferred.

[0028] The impregnation method used in the impregnation and loading process is preferably a co-impregnation method. The method for loading the barium compound or strontium compound may be a known method such as a conventional impregnation method, an incipient wetness method, a precipitation method, or an ion exchange method.

[0029] The amount of barium compound or strontium compound supported on the catalyst support shall be such that the amount of barium or strontium supported in the resulting catalyst falls within the above range.

[0030] Here, a catalyst support mainly composed of cerium oxide can be produced, for example, by calcining a cerium compound (cerium acetylacetonate hydrate, cerium hydroxide, cerium sulfate, cerium acetate, cerium nitrate, cerium ammonium nitrate, cerium carbonate, cerium oxalate, cerium perchlorate, cerium phosphate, cerium stearate, etc.) in an air atmosphere.

[0031] (Firing process) In the firing process, the catalyst support, which has been impregnated and supported, is fired to produce the catalyst. In the firing process, the firing temperature is preferably 350 to 800°C, and more preferably 400 to 700°C. The firing time is preferably 1 to 7 hours, and more preferably 2 to 4 hours. The firing process is carried out, for example, in an air atmosphere using equipment capable of reaching a sufficient temperature, such as a muffle furnace.

[0032] Furthermore, the catalyst support after the impregnation and loading process may be subjected to a drying treatment before the calcination process. The drying temperature is preferably 80 to 120°C, and more preferably 90 to 110°C. The drying time is preferably 1 to 10 hours. Drying should be carried out, for example, in an air atmosphere using equipment capable of reaching a sufficient temperature, such as a dryer.

[0033] The catalyst of this disclosure is obtained through the above process. The resulting catalyst may be granulated to improve the fluidity of the reaction gas. Examples of granulation methods include extrusion molding and compression molding.

[0034] <Method for producing carbonate esters> The method for producing carbonate esters according to the present disclosure involves reacting carbon dioxide and at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point above 100°C in the presence of a solid catalyst comprising the carbonate ester production catalyst of the present disclosure and a solvent, under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and the solvent, thereby producing carbonate esters and by-product water (see scheme below), and removing the by-product water from the reaction site by evaporation.

[0035] [ka] [ka]

[0036] The method for producing the carbonate ester described herein will be explained in detail below.

[0037] In the method for producing carbonate esters of the present invention, in the reaction step, a carbonate ester is produced by directly reacting an alcohol with a boiling point above 100°C with carbon dioxide in the presence of a solid catalyst consisting of the carbonate ester production catalyst of the present disclosure and a solvent. In this reaction process, when an alcohol with a boiling point above 100°C is reacted with carbon dioxide, not only carbonate esters but also by-product water is produced.

[0038] If the reaction conditions are set so 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 solvent, the solvent and alcohol remain in liquid state, the by-product water evaporates and is removed from the reaction site, and the formation of carbonate esters is promoted. Furthermore, the evaporated by-product water should be removed from the reaction field by a stream of carbon dioxide.

[0039] Here, "removing by-product water from the reaction site by evaporation" includes not only removing all by-product water from the reaction site where the carbonate ester is produced (i.e., the region where the alcohol, solid catalyst, and solvent are present), but also the possibility that some by-product water may remain in the reaction site. Note that any by-product water remaining in the reaction site can be separated by distillation.

[0040] (Solid catalyst) The solid catalyst used is a solid catalyst comprising the carbonate ester production catalyst described above.

[0041] Solid catalysts are used in a dispersed or immobilized form in a solvent. Immobilizing a solid catalyst in a solvent means, for example, immersing a molded body on which the solid catalyst is coated (such as a honeycomb made of cordierite or stainless steel) in a solvent.

[0042] If the catalyst performance deteriorates, it can be regenerated by removing the catalyst from the reactor, washing it with an alcohol such as methanol or ethanol, and then drying it in air at a temperature of around 100°C.

[0043] When using a solid catalyst reagent, it may be used as is, or a dried product (after drying the reagent in an air atmosphere) or a calcined product (after calcination) may be used. Alternatively, a solid catalyst can be used, which is produced by precipitating a solution of dissolved cerium, filtering, drying, and calcining it.

[0044] (solvent) The solvent is used to disperse or immobilize the solid catalyst and dissolve the alcohol, which is the reaction substrate. A solvent that does not affect the reaction between carbon dioxide and alcohol is used. Suitable solvents include aliphatic hydrocarbons, aromatic hydrocarbons, ethers, secondary amines, and tertiary amines, as long as their boiling point is above 100°C. Among these, 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, and diphenyl ether are preferred as solvents, given that they do not react with catalysts or alcohols, and offer high catalyst dispersibility and a high boiling point. Among these, from the viewpoint of producing carbonate esters with high efficiency, one or more solvents selected from the group consisting of toluene, decane, dodecane, and ether-based solvents are preferred as the solvent. In particular, ether-based solvents (solvents having ether bonds) or hydrophobic solvents are preferred as the solvent. Furthermore, a mixture of ether-based solvents and hydrophobic solvents may be used. Here, a hydrophobic solvent is a solvent that exhibits solubility (g / L-H2O) such that the amount that dissolves in 1 L of water at 25°C is 10 g or less.

[0045] (carbon dioxide) Carbon dioxide can be obtained not only from industrial gases that have been prepared, but also from exhaust gases separated and recovered from factories, steel mills, power plants, etc. that manufacture each product.

[0046] (alcohol) The alcohol used is at least one alcohol selected from the group consisting of monohydric and dihydric alcohols.

[0047] Examples of monohydric alcohols include 1-butanol, isobutyl alcohol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, and dodecanol. Examples of dihydric alcohols 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.

[0048] Among these, monohydric and dihydric alcohols are appropriately selected according to the properties required of the target product, the carbonate ester. However, from the viewpoint of boiling point and the proportion of carbon dioxide incorporated into the product, alcohols with 2 to 10 carbon atoms are preferred, and alcohols with 4 to 6 carbon atoms are more preferred. Furthermore, of monohydric and dihydric alcohols, monohydric alcohols are preferred from the viewpoint of producing polycarbonate and its intermediates, while dihydric alcohols are preferred from the viewpoint of producing polyurethane intermediates (polycarbonate diols). Here, from the viewpoint of efficiently producing carbonate esters, a particularly preferred monohydric alcohol is a monohydric alcohol having 4 to 10 carbon atoms. On the other hand, from the same viewpoint, a particularly preferred dihydric alcohol is a dihydric alcohol having 2 to 10 carbon atoms (preferably 4 to 6 carbon atoms). In particular, a dihydric alcohol is preferred as the alcohol. Furthermore, a polycarbonate diol is preferred as the resulting carbonate ester.

[0049] Although the boiling point of alcohol is above 100°C, from the viewpoint of separation of alcohol and by-product water by distillation, 101 to 300°C is preferred, and 110 to 250°C is more preferred.

[0050] (Reaction conditions) The reaction conditions for carbon dioxide and alcohol 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 solvent. The reaction temperature depends on the boiling points of the alcohol and solvent, but from the viewpoint of highly efficient carbonate ester formation, 101 to 300°C is preferred, and 110 to 260°C is more preferred.

[0051] The reaction pressure may be at atmospheric pressure (1 atmosphere) or pressurized. When pressurized, the reactor wall thickness is required, so from the viewpoint of equipment costs, it is preferable that the reaction pressure be less than 2 MPa. Since it will no longer be classified as a high-pressure gas facility, it is even more preferable that the reaction pressure be less than 1 MPa.

[0052] The reaction between carbon dioxide and alcohol is carried out, for example, by introducing carbon dioxide into a solvent in which the alcohol is dissolved, with a solid catalyst dispersed or immobilized as the reaction site. It is preferable to introduce the carbon dioxide by bubbling it using, for example, a bubbling device.

[0053] For example, at a laboratory-level beaker scale, carbon dioxide can be blown into a beaker containing the solvent through a tube with an inner diameter of about 2 mm. A bubbler can also be attached to the end of the tube. At a full-scale reactor level, a sparger can be used to introduce carbon dioxide and promote fluid flow within the reactor.

[0054] The amounts of carbon dioxide, alcohol, catalyst, and solvent introduced should preferably be adjusted appropriately according to the reactor capacity.

[0055] The components remaining after the reaction between carbon dioxide and alcohol can be separated by cooling or distillation and reused in the reaction, or they can be discharged as is. Regarding carbon dioxide, the choice between recycling it or discharging it directly can be made from a Life Cycle Assessment (LCA) perspective.

[0056] Next, specific examples of the method and apparatus for producing carbonate esters according to the present invention will be described with reference to the drawings.

[0057] [First Embodiment] Figure 1 is a schematic diagram showing a production apparatus for carbonate ester according to the first embodiment. The apparatus for producing carbonate ester according to the first embodiment includes, for example, a reaction tower 10 that reacts carbon dioxide with alcohol to produce carbonate ester and by-product water, as shown in Figure 1. Then, the reaction process is carried out in reaction tower 10.

[0058] Furthermore, the carbonate ester production apparatus according to the first embodiment includes, for example, a cooling tower 11 (an example of a first cooling tower), a distillation tower 12 (an example of a first distillation tower), a cooling tower 13, and a separation tower 14 for cooling, distilling, separating, and regenerating each component discharged as a gas phase from the reaction tower 10. Then, in each column, a cooling process (an example of the first cooling process), a distillation process (an example of the first distillation process), another cooling process, and a separation process are carried out.

[0059] Furthermore, the production apparatus for carbonate ester according to the first embodiment includes, for example, a distillation column 21 and a separation column 22 for distilling, cooling, separating, and regenerating each component discharged as a liquid phase from the reaction column 10. Then, in each column, a distillation process (an example of a second distillation process) and a separation process are carried out.

[0060] In Figure 1, 100A represents the alcohol ROH introduced into reaction tower 10. 100B represents the carbon dioxide (CO2) introduced into reaction tower 10. 100C represents the solvent (Sol) introduced into reaction tower 10. 101 represents the gas phase discharged from reaction tower 10 (unreacted carbon dioxide CO2, unreacted alcohol ROH, by-product water H2O, and solvent Sol). 102 represents the gas phase (unreacted carbon dioxide CO2) discharged from the cooling tower 11 (an example of the first cooling tower). 103 shows the liquid phase (unreacted alcohol ROH, by-product water H2O, and solvent Sol) discharged from the cooling tower 11 (an example of the first cooling tower). 104 is discharged from distillation column 12 (an example of the first distillation column) and shows the gas phase (by-product water H2O). 105 is discharged from distillation column 12 (an example of the first distillation column) and shows the liquid phase (unreacted alcohol ROH and solvent Sol). 106 represents the liquid phase (by-product water H2O) discharged from the cooling tower 13. 107 represents the liquid phase (unreacted alcohol ROH) discharged from the separation column 14. 108 represents the liquid phase (solvent Sol) discharged from the separation column 14. 201 represents the liquid phase (carbonate ester C-ester, unreacted alcohol ROH, and solvent Sol) discharged from reaction tower 10. Line 202 shows the gas phase (unreacted alcohol ROH and solvent Sol) discharged from distillation column 21 (an example of a second distillation column). 203 shows the liquid phase (carbonate ester C-ester) discharged from distillation column 21 (an example of a second distillation column). 204 represents the liquid phase (unreacted alcohol ROH) discharged from the separation column 22. 205 represents the liquid phase (solvent Sol) discharged from the separation column 22. Although not shown in the diagram, each tower is connected by piping.

[0061] (Reaction tower 10: Reaction process) The reaction process is carried out in reaction tower 10. The reaction step involves supplying carbon dioxide and at least one alcohol selected from the group consisting of monohydric and dihydric alcohols with a boiling point above 100°C to a reactor 10A containing a solid catalyst and a solvent, and reacting the carbon dioxide and alcohol under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and solvent to produce a carbonate ester and by-product water.

[0062] Specifically, a solvent with an immobilized solid catalyst is placed in reactor 10A. Liquid alcohol is supplied to the solvent in reactor 10A from above, while atmospheric pressure (gas phase) carbon dioxide is introduced from below by bubbling. The reactor 10A is then brought to a predetermined reaction temperature and pressure. This causes the carbon dioxide and alcohol to react, producing carbonate ester and by-product water.

[0063] The reaction tower 10 (and its reactor 10A) may be any of the following types of reactors: a batch reactor, a semi-batch reactor, or a flow reactor (continuous tank reactor, tubular reactor, etc.).

[0064] (Cooling tower 11 (an example of the first cooling tower)) In the cooling tower 11, a cooling process (the first cooling process) is carried out. The cooling process cools the unreacted carbon dioxide, unreacted alcohol (alcohol obtained by vaporizing some of the unreacted alcohol in reactor 10A of reaction tower 10), by-product water (evaporated by-product water), and solvent (solvent obtained by vaporizing some of the solvent in reactor 10A of reaction tower 10) that are discharged as gas phase from reactor 10A in reaction tower 10. At this time, the unreacted alcohol, by-product water, and solvent are discharged from reaction tower 10 carried by the gaseous flow of unreacted carbon dioxide. This separates the mixture into a gas phase containing unreacted carbon dioxide and a liquid phase containing unreacted alcohol, by-product water, and solvent. These components are then discharged from the cooling tower 11.

[0065] Here, the cooling temperature in the cooling tower 11 (cooling process) is set below the temperature of unreacted alcohol, by-product water, and solvent (specifically, below 100°C).

[0066] (Distillation column 12 (an example of the first distillation column)) In the distillation column 12, the distillation process (the first distillation process) is carried out. In the distillation process, the unreacted alcohol, by-product water, and solvent, which have been separated as a liquid phase in the cooling tower 11 (cooling process), are distilled. This separates the mixture into a gas phase containing by-product water and a liquid phase containing unreacted alcohol and solvent. These components are then discharged from the distillation column 12.

[0067] Here, the distillation temperature in the distillation column 12 (distillation process) is set to be above the boiling point of the by-product water and below the boiling points of the unreacted alcohol and solvent.

[0068] (Cooling tower 13) In cooling tower 13, the cooling process is carried out. In the cooling process, the by-product water discharged as a gaseous phase from the distillation column 12 (distillation process) is cooled. As a result, the by-product water is liquefied. The by-product water is then discharged as a liquid phase from the cooling column 13.

[0069] (separation tower 14) In the separation column 14, for example, a separation process is carried out to separate unreacted alcohol and solvent using a distillation column and a cooling column. In the distillation and cooling process, the unreacted alcohol and solvent discharged as a liquid phase from the distillation column 12 (distillation process) are distilled and cooled in such a way that they are separated and liquefied using the difference in their boiling points. As a result, the mixture is separated into a liquid phase consisting of unreacted alcohol and a solvent. These components are then discharged from the separation column 14.

[0070] (Distillation column 21 (an example of a second distillation column)) In the distillation column 21, the distillation process (an example of the second distillation process) is carried out. In the distillation process, the carbonate ester, unreacted alcohol, and solvent discharged as the liquid phase from reactor 10A in reaction column 10 (reaction process) are distilled. This separates the mixture into a gas phase consisting of unreacted alcohol and solvent, and a liquid phase consisting of carbonate ester. The unreacted alcohol and solvent are then discharged from the distillation column 21, and the target product, carbonate ester, is recovered from the distillation column 21.

[0071] Here, the distillation temperature in the distillation column 21 (distillation process) is set to be above the boiling point of the unreacted alcohol and solvent, and below the boiling point of the carbonate ester.

[0072] (Separation tower 22) In the separation column 22, for example, a separation process is carried out to separate unreacted alcohol and solvent using two cooling columns. In the separation process, for example, the unreacted alcohol and solvent discharged as a gas phase from the distillation column 21 (distillation process) are cooled in such a way that they are separated and liquefied using the difference in their boiling points. As a result, the mixture is separated into a liquid phase consisting of unreacted alcohol and a solvent. These components are then discharged from the separation column 22.

[0073] (reuse) In the production apparatus for carbonate ester according to the first embodiment, unreacted carbon dioxide (gas phase) separated in the cooling tower 11 (distillation step), unreacted alcohol and solvent separated in the separation tower 14, and unreacted alcohol and solvent separated in the separation tower 22 are reused in the reaction tower 10 (reaction step). Furthermore, the unreacted alcohol and solvent separated in distillation columns 12 and 21 (i.e., the mixture of unreacted alcohol and solvent) may be reused directly in reaction column 10 (reaction step) without further separation.

[0074] Through the above process, carbonate esters are produced in the carbonate ester production apparatus according to the first embodiment.

[0075] [Second Embodiment] Figure 2 shows a schematic diagram of a production apparatus for carbonate ester according to the second embodiment. The carbonate ester production apparatus according to the second embodiment, as shown in Figure 2, for example, further comprises a separation column 31 and a catalyst regeneration column 32 in addition to the carbonate ester production apparatus according to the first embodiment. The carbonate ester production apparatus according to the second embodiment has the same configuration as the carbonate ester production apparatus according to the first embodiment, except that it includes a separation column 31 and a catalyst regeneration column 32.

[0076] In Figure 2, 301 represents the solid catalyst Cat discharged as a solid phase along with the liquid phase (carbonate ester C-ester, unreacted alcohol ROH, and solvent Sol). Label 302 shows the solid catalyst Cat separated in the separation column 31. 302 represents the solid catalyst Cat regenerated in the catalyst regeneration tower 32. Other symbols indicate the same objects as those indicated in Figure 1. However, 201 indicates the liquid phase separated in separation column 31 (carbonate ester C-ester, unreacted alcohol ROH, and solvent Sol).

[0077] (Separation tower 31) In the separation tower 31, the separation process is carried out. In the separation step, the solid catalyst discharged as a solid phase along with the liquid phase (carbonate ester, unreacted alcohol, and solvent) is separated from the liquid phase. Specifically, the solid catalyst is separated from the liquid phase using a filter or the like. The separated solid catalyst is then discharged from the separation tower 31 as a slurry containing the solid catalyst. The solid catalyst and the separated liquid phase (carbonate ester, unreacted alcohol, and solvent) are then discharged from the separation column 31 and sent to the distillation column 21.

[0078] (Catalyst regeneration tower 32) In the catalyst regeneration tower 32, the catalyst regeneration process is carried out. In the catalyst regeneration process, the solid catalyst separated in the separation column 31 (separation process) is regenerated. Specifically, in the catalyst regeneration process, for example, the solid catalyst is regenerated by calcining it to burn off impurities and other substances on the solid catalyst. The firing process is carried out, for example, at 400-700°C (preferably 500-600°C) for about 3 hours. To prevent structural damage to the solid catalyst due to rapid temperature increases, it is preferable to dry it at 110°C for about 2 hours before firing.

[0079] (reuse) Furthermore, in the carbonate ester production apparatus according to the second embodiment, the solid catalyst regenerated in the catalyst regeneration tower 32 (catalyst regeneration process) is reused in the reaction tower 10 (reaction process).

[0080] [Other forms] In the production apparatus (or production method) of carbonate ester according to the first and second embodiments, a configuration was described in which the carbonate ester, unreacted alcohol, and solvent separated as a liquid phase in a distillation column 21 (distillation step) are distilled to separate the unreacted alcohol and solvent as a gas phase and the carbonate ester as a liquid phase. However, the apparatus (or method) for producing carbonate ester according to this embodiment may be equipped with a cooling tower (an example of a second cooling tower) instead of a distillation tower 21, and in the distillation tower 21 (distillation step), the carbonate ester, unreacted alcohol, and solvent separated as a liquid phase are cooled to separate them into a liquid phase consisting of unreacted alcohol and solvent, and a solid phase consisting of carbonate ester.

[0081] In this type of production apparatus (or method) for carbonate esters, the carbonate ester is cooled to below its melting point, solidified, and then recovered using a filter or the like.

[0082] In the production apparatus (or production method) of carbonate ester according to the first and second embodiments, the liquid phase component discharged from the reaction column 10 may contain trace amounts of by-product water. In that case, a distillation column (distillation process) and a cooling column (cooling process) may be provided to separate the by-product water from the component discharged from the reaction column 10. However, separating trace amounts of by-product water from the liquid phase components discharged from the reaction tower 10 is difficult and requires a large amount of energy; therefore, it is preferable not to separate the trace amounts of by-product water. [Examples]

[0083] The present invention will be described in more detail below with reference to examples, but the conditions in the examples are merely one example of conditions adopted to confirm the feasibility and effectiveness of the present invention, and the present invention is not limited to this one example of conditions. The present invention can adopt various conditions as long as they do not depart from the spirit of the invention and achieve the objectives of the present invention.

[0084] (Preparation of barium-supported cerium oxide catalyst) Barium nitrate was used as a barium precursor to support barium on cerium oxide using an impregnation method, resulting in a barium concentration of 0.6 mol% relative to the cerium oxide. After barium impregnation, the cerium oxide was dried at 110°C for 12 hours, and then calcined at 500°C in an air atmosphere for 3 hours to prepare the catalyst. Similarly, barium-supported cerium oxide catalysts were prepared by changing the calcination temperature and the amount of barium supported relative to cerium, according to Table 1.

[0085] (Preparation of strontium-supported cerium oxide catalyst) Strontium nitrate was used as a strontium precursor to support cerium oxide using an impregnation method, resulting in a strontium concentration of 0.6 mol% relative to the cerium oxide. After strontium impregnation, the cerium oxide was dried at 110°C for 12 hours, and then calcined at 500°C in an air atmosphere for 3 hours to prepare the catalyst. Similarly, strontium-supported cerium oxide catalysts were prepared by changing the calcination temperature and the amount of strontium supported relative to the cerium, according to Table 2.

[0086] (Examples, Comparative Examples) In a 200 mL flow-through, round-bottom flask (top cooling temperature 4°C), 0.10 g of solid catalyst, 2.0 g of 1,6-hexanediol (boiling point 250°C) as an alcohol, and 2.0 g of triethylene glycol dimethyl ether (boiling point 216°C) and 3.0 g of diphenyl ether (boiling point 258°C) as solvents were introduced. Subsequently, CO2 was introduced into the flask by bubbling 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 210°C (483.15 K) for a reaction time of 4 hours. Afterward, the flask was air-cooled to room temperature, and the product was collected and analyzed by gas chromatography (GC) to determine the yield of the carbonate ester.

[0087] Table 1 shows the yields of carbonate esters in examples where barium-supported cerium oxide catalysts were used as solid catalysts, with variations in calcination temperature and barium load relative to cerium. Table 2 shows the yields of carbonate esters in examples where strontium-supported cerium oxide catalysts were used as solid catalysts, with variations in calcination temperature and the amount of strontium supported relative to cerium. In Tables 1 and 2, the yields of carbonate esters shown in bold frames are examples corresponding to this embodiment.

[0088] [Table 1]

[0089] [Table 2]

[0090] From the above, it can be seen that in this embodiment, carbonate esters can be produced with high efficiency using a catalyst utilizing cerium oxide. [Explanation of symbols]

[0091] 10 Reaction towers 11. Cooling Tower (An example of the first cooling tower) 12. Distillation column (an example of a first distillation column) 13 Cooling Tower 14 Separation tower 21. Distillation column (an example of a second distillation column) 22 Separation tower

Claims

1. The catalyst carrier mainly composed of cerium oxide and barium or strontium supported on the catalyst carrier, The amount of barium supported on the cerium oxide is 0.20 to 6.00 mol%, The amount of strontium supported on the cerium oxide is 0.25 to 3.00 mol%. A catalyst for producing carbonate esters using carbon dioxide and alcohol as raw materials.

2. The catalyst for producing carbonate esters according to claim 1, wherein the alcohol is a dihydric alcohol.

3. The catalyst for producing a carbonate ester according to claim 1, wherein the carbonate ester is a polycarbonate diol.

4. A method for producing a catalyst for carbonate ester production according to any one of claims 1 to 3, An impregnation and support step in which a barium compound or a strontium compound is impregnated and supported on the catalyst support, A calcination step to produce a catalyst by calcining the catalyst support after the impregnation and loading step, Having, A method for producing a catalyst for carbonate ester production using carbon dioxide and alcohol as raw materials.

5. The method for producing a catalyst for carbonate ester production according to claim 4, wherein the firing temperature in the firing step is 350 to 800°C.

6. A method for producing carbonate esters, comprising reacting carbon dioxide with at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point above 100°C in the presence of a solid catalyst comprising a catalyst for producing carbonate esters according to any one of claims 1 to 3 and a solvent, under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and the solvent, thereby producing carbonate esters and by-product water, and removing the by-product water from the reaction site by evaporation.

7. The method for producing a carbonate ester according to claim 6, wherein the evaporated by-product water is removed from the reaction field by a stream of carbon dioxide.

8. The method for producing a carbonate ester according to claim 6, wherein the alcohol is a monohydric alcohol having 4 to 10 carbon atoms.

9. The method for producing a carbonate ester according to claim 6, wherein the alcohol is a dihydric alcohol having 2 to 10 carbon atoms.

10. The method for producing a carbonate ester according to claim 9, wherein the dihydric alcohol is a dihydric alcohol having 4 to 6 carbon atoms.

11. The method for producing a carbonate ester according to claim 6, wherein the solvent is a solvent that comprises one or more selected from the group consisting of toluene, decane, dodecane, and ether-based solvents.

12. A reaction step comprising: supplying carbon dioxide and at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point greater than 100°C to a reactor containing a solid catalyst comprising a catalyst for producing carbonate ester according to any one of claims 1 to 3 and a solvent; and reacting the carbon dioxide and the alcohol under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and the solvent to produce carbonate ester and by-product water; A first cooling step involves cooling the unreacted carbon dioxide, unreacted alcohol, by-product water, and solvent discharged as a gas phase from the reactor in the reaction step, thereby separating them into a gas phase of unreacted carbon dioxide and a liquid phase of unreacted alcohol, by-product water, and solvent. A first distillation step is performed to separate the unreacted alcohol, the by-product water, and the solvent, which have been separated as a liquid phase in the first cooling step, into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase by distillation. A second distillation step in which the carbonate ester, unreacted alcohol, and solvent discharged as a liquid phase from the reactor in the reaction step are distilled to separate them into a gas phase consisting of the unreacted alcohol and solvent and a liquid phase consisting of the carbonate ester, or a second cooling step in which the carbonate ester, unreacted alcohol, and solvent discharged as a liquid phase from the reactor in the reaction step are cooled to separate them into a liquid phase consisting of the unreacted alcohol and solvent and a solid phase consisting of the carbonate ester, It has, The unreacted carbon dioxide separated in the first cooling step, the unreacted alcohol and solvent separated in the first distillation step, and the unreacted alcohol and solvent separated in the second distillation step or the second cooling step are reused in the reaction step. A method for producing carbonate esters.

13. A separation step is performed to separate the solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction step, A catalyst regeneration step for regenerating the solid catalyst separated in the separation step, It further possesses, The method for producing a carbonate ester according to claim 12, wherein the solid catalyst regenerated in the catalyst regeneration step is reused in the reaction step.

14. A reaction tower comprising a reactor containing a solid catalyst comprising a catalyst for producing carbonate esters according to any one of claims 1 to 3 and a solvent, wherein carbon dioxide and at least one alcohol selected from the group consisting of monohydric and dihydric alcohols having a boiling point greater than 100°C are supplied to the reactor, and the carbon dioxide and the alcohol are reacted under conditions where the reaction temperature is 100°C or higher and below the boiling points of the alcohol and the solvent to produce carbonate esters and by-product water, A first cooling tower cools the unreacted carbon dioxide, unreacted alcohol, by-product water, and solvent discharged as a gas phase from the reactor in the reaction tower, separating them into a gas phase of unreacted carbon dioxide and a liquid phase of unreacted alcohol, by-product water, and solvent. A first distillation column separates the unreacted alcohol, the by-product water, and the solvent, which have been separated as a liquid phase in the first cooling tower, into the by-product water as a gas phase and the unreacted alcohol and the solvent as a liquid phase by distillation. A second distillation column for distilling the carbonate ester, unreacted alcohol, and solvent discharged as a liquid phase from the reactor in the reaction tower to separate them into a gas phase consisting of the unreacted alcohol and solvent and a liquid phase consisting of the carbonate ester, or a second cooling column for cooling the carbonate ester, unreacted alcohol, and solvent discharged as a liquid phase from the reactor in the reaction tower to separate them into a liquid phase consisting of the unreacted alcohol and solvent and a solid phase consisting of the carbonate ester, Equipped with, The unreacted carbon dioxide separated in the first cooling tower, the unreacted alcohol and solvent separated in the first distillation tower, and the unreacted alcohol and solvent separated in the second distillation tower or the second cooling tower are reused in the reaction tower. A device for producing carbonate esters.

15. A separation tower for separating the solid catalyst discharged as a solid phase together with the liquid phase from the reactor in the reaction tower, A catalyst regeneration tower for regenerating the solid catalyst separated in the separation tower, Furthermore, The apparatus for producing carbonate esters according to claim 14, wherein the solid catalyst regenerated in the catalyst regeneration tower is reused in the reaction tower.

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