METHOD FOR PRODUCING ETHYL METHYL CARBONATE

Abstract

The present invention is an ethyl methyl carbonate production method having a distillation step A for supplying a feed material containing dimethyl carbonate, ethyl methyl carbonate and ethanol to a distillation column A and extracting a fraction AB from the bottom of the distillation column A. The feed material contains dimethyl carbonate at a proportion of 25 mol% or more relative to the total amount of the feed material and ethyl methyl carbonate at a proportion of 12 mol% or more relative to the total amount of the feed material. The dimethyl carbonate / (ethanol+ethyl methyl carbonate) molar ratio in the feed material is 0.5-5.6. The ratio of ethanol relative to ethyl methyl carbonate in the fraction AB is 20 ppm by mass or less. The ratio of methanol relative to ethyl methyl carbonate in the fraction AB is 20 ppm by mass or less.

Description

Method for producing ethyl methyl carbonate

[0001] The present invention relates to a method for producing ethyl methyl carbonate.

[0002] Ethyl methyl carbonate, which is used as an organic solvent in battery electrolytes, is generally produced by a transesterification reaction between dimethyl carbonate and ethanol.

[0003] Ethyl methyl carbonate, specified to have a methanol concentration of 20 mass ppm or less and an ethanol concentration of 20 mass ppm or less, is commonly used as a battery electrolyte. However, because the raw material ethanol and the product ethyl methyl carbonate have an azeotropic composition at normal pressure, rectification to achieve the above-mentioned alcohol concentrations is inefficient in terms of energy efficiency and results in a large loss of ethyl methyl carbonate.

[0004] For example, Patent Document 1 proposes a method for separating ethanol from ethyl methyl carbonate using a pressurized column, and Patent Document 2 proposes a means for improving the energy efficiency required for purifying ethyl methyl carbonate by using a heat pump.

[0005] CN212687934UCN110105216A

[0006] It is known that, in the distillation purification of ethyl methyl carbonate, dimethyl carbonate and methanol, dimethyl carbonate and ethanol, and ethyl methyl carbonate and ethanol form azeotropic compositions at normal pressure. In particular, in the purification of ethyl methyl carbonate to a high purity, the formation of an azeotropic composition between ethyl methyl carbonate and ethanol becomes a problem, and purification has been carried out using a method with low energy efficiency to remove the alcohols from these methanol and ethanol.

[0007] Patent Documents 1 and 2 disclose a method of removing the alcohol by applying pressure to break the azeotropy between methyl ethyl carbonate and alcohol. However, the pressurization raises the boiling points of all components, resulting in a high temperature, which requires a large number of heat sources, resulting in low energy efficiency.

[0008] Therefore, an object of the present invention is to efficiently produce ethyl methyl carbonate having a low content of ethanol and methanol.

[0009] The present inventors have found that the above-mentioned problems can be solved by making a predetermined amount or more of dimethyl carbonate present during the distillation purification of ethyl methyl carbonate.

[0010] That is, the present invention includes the following embodiments: <1> A feed containing dimethyl carbonate, ethyl methyl carbonate, and ethanol is supplied to a distillation column A, and a fraction A is obtained from the bottom of the distillation column A. Ｂ the feed contains dimethyl carbonate in a proportion of 25 mol % or more based on the total amount of the feed and ethyl methyl carbonate in a proportion of 12 mol % or more based on the total amount of the feed, the molar ratio of dimethyl carbonate / (ethanol+ethyl methyl carbonate) in the feed is 0.1 to 2.0, and the fraction A Ｂ The ratio of ethanol to ethyl methyl carbonate in the fraction A is 20 mass ppm or less, and Ｂ a ratio of methanol to ethyl methyl carbonate in the fraction A is 20 mass ppm or less; Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ a distillation step B for extracting the fraction B; Ｂ is supplied to a distillation column C, and fraction C is extracted from the top of the distillation column C. Ｌ The method further comprises a distillation step C for extracting the fraction C. Ｌ (2) the purity of ethyl methyl carbonate in the fraction A is 99.99% by mass or more; or Ｂ is supplied to a distillation column D, and fraction D is obtained from the bottom of the distillation column D. Ｂ From the top of the column, fraction D Ｌ From the middle of the distillation column D, fraction D Ｓ The method further comprises a distillation step D for extracting the fraction D. Ｓ(3) the purity of ethyl methyl carbonate in the fraction A is 99.99% by mass or more; or Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ a distillation step B for extracting the fraction B; Ｂ is supplied to a distillation column D, and fraction D is obtained from the bottom of the distillation column D. Ｂ From the top of the column, fraction D Ｌ From the middle of the distillation column D, fraction D Ｓ The method further comprises a distillation step D for extracting the fraction D. Ｓ <1> The method for producing ethyl methyl carbonate according to <1>, wherein the purity of ethyl methyl carbonate in the distillation column A is 99.99% by mass or more. <3> The method for producing ethyl methyl carbonate according to <1> or <2>, wherein the top pressure of the distillation column A is 0 kPaG to 50 kPaG. <4> The method for producing ethyl methyl carbonate according to any one of <1> to <3>, wherein the method for supplying at least a portion of dimethyl carbonate from the feed to the distillation column A is by sole liquid addition using a pump. <5> The method for producing ethyl methyl carbonate according to any one of <1> to <4>, wherein the feed is introduced from an intermediate portion of the distillation column A. <6> The method for producing ethyl methyl carbonate according to any one of <1> to <5>, wherein the feed contains ethanol in a proportion of 0.5 mol % or more based on the total amount of the feed. <7> The method for producing ethyl methyl carbonate according to any one of <1> to <6>, wherein the distillation column A is equipped with trays and / or packings as internals. <8> The method for producing ethyl methyl carbonate according to any one of <1> to <7>, further comprising a reaction step of transesterifying dimethyl carbonate and ethanol in a reaction apparatus to obtain a reaction composition before the distillation step A, and supplying the reaction composition to the distillation column A as at least a part of the feed. <9> The method for producing ethyl methyl carbonate according to any one of <1> to <7>, further comprising a reaction step of transesterifying dimethyl carbonate and ethanol in a reaction apparatus to obtain a reaction composition before the distillation step A, and supplying the reaction composition to the distillation column A as at least a part of the feed. Ｂ or fraction D Ｂand a reaction step of distilling the fraction A from the distillation product to obtain diethyl carbonate having a purity of 99.99% by mass or more. Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ a distillation step B for extracting the fraction B; Ｂ is supplied to a distillation column C, and fraction C is extracted from the top of the distillation column C. Ｌ a distillation step C in which the reaction composition is fed to the distillation column A as at least a part of the feed, and the fraction C is extracted. Ｌ <9> The method for producing ethyl methyl carbonate according to any one of <1> to <9>, wherein the purity of ethyl methyl carbonate in the ethyl methyl carbonate solution is 99.99% by mass or more.

[0011] According to the present invention, it is possible to produce ethyl methyl carbonate having a low content of ethanol and methanol with high efficiency.

[0012] Figure 1 is a schematic diagram of a production facility used in the method for producing ethyl methyl carbonate according to this embodiment. Figure 2 is a schematic diagram of a production facility used in the method for producing ethyl methyl carbonate according to this embodiment. Figure 3 is a schematic diagram of a production facility used in the method for producing ethyl methyl carbonate according to this embodiment. Figure 4 is a schematic diagram of a production facility used in the method for producing ethyl methyl carbonate according to this embodiment. Figure 5 is a schematic diagram of a production facility used in the method for producing ethyl methyl carbonate according to this embodiment.

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible within the scope of the gist of the present invention. In the drawings, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0014] The meanings of terms and abbreviations used in this specification are explained below. "EMC" means ethyl methyl carbonate. "DMC" means dimethyl carbonate. "DEC" means diethyl carbonate. "MeOH" means methanol. "EtOH" means ethanol. "A", "B", "C" and the like in distillation column A, distillation column B, distillation column C, step A, step B, step C are symbols simply used to describe the distillation column and do not limit the configuration, order, number, etc. of the distillation column.

[0015] Numerical ranges indicated using "to" indicate ranges that include the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range in one stage can be arbitrarily combined with the upper limit or lower limit of a numerical range in another stage.

[0016] The method for producing ethyl methyl carbonate according to this embodiment includes a distillation step of supplying a feed containing dimethyl carbonate, ethyl methyl carbonate, and ethanol to a distillation column and withdrawing the components from the bottom of the distillation column, wherein the feed contains dimethyl carbonate at a ratio of 15 mol % or more relative to the total amount of the feed and ethyl methyl carbonate at a ratio of 12 mol % or more relative to the total amount of the feed, the molar ratio of dimethyl carbonate / (ethanol + ethyl methyl carbonate) in the feed is 0.1 to 2.0, and the fraction A is Ｂ The ratio of ethanol to ethyl methyl carbonate in the fraction A is 20 mass ppm or less, and Ｂ In the present embodiment, the ratio of methanol to ethyl methyl carbonate in the distillation column is 20 mass ppm or less. According to the present embodiment, it is possible to produce ethyl methyl carbonate with low ethanol and methanol contents with high efficiency. More specifically, in the present embodiment, the alcohol content is reduced, so that the reflux ratio of the distillation column can be reduced, or the amount of EMC loss can be reduced, and therefore EMC can be produced with high efficiency.

[0017] In the EMC production method according to this embodiment, it was surprisingly found that the purity of EMC can be increased efficiently by increasing the concentration of DMC in the feed to the distillation column. The mechanism behind this effect is believed to be that by increasing the concentration of DMC in the feed to a predetermined value or higher, as described above, the azeotropic distillation effect can eliminate the formation of an azeotropic composition between EMC and EtOH at normal pressure.

[0018] The method for producing EMC according to this embodiment includes, for example, a reaction step of transesterifying DMC and EtOH in a reactor R to obtain a reaction composition; supplying the reaction composition as a feed containing DMC, EMC, and EtOH to a distillation column A, and extracting a fraction A from the bottom of the distillation column A. Ｂ a distillation step A for extracting the fraction A; Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ a distillation step B for extracting the fraction B; Ｂ is supplied to a distillation column C, and fraction C is extracted from the top of the distillation column C. Ｌ and C. a distillation step for extracting the above.

[0019] In the method for producing EMC according to this embodiment, the product obtained by any of the steps may be the target product. For example, a composition containing EMC with a reduced alcohol content is obtained from the reaction composition by distillation step A. EMC with a purity of 99.99% by mass or more is obtained from the reaction composition by distillation step A, distillation step B, and distillation step C. EMC with a purity of 99.99% by mass or more is used for applications such as battery electrolyte.

[0020] <Reaction Step> In the reaction step, a reaction composition is obtained by transesterification of DMC and EtOH in the reactor R. The reaction composition obtained by the transesterification reaction may contain EMC, DMC, DEC, MeOH, and EtOH.

[0021] The raw material supplied to the reactor R includes DMC and EtOH. The various components may be compounds derived from biomass. EtOH may be bioethanol, or DMC obtained using DMC biomethanol as a raw material. The raw material may also contain an alkali metal compound as a catalyst. The raw material may be continuously supplied.

[0022] Examples of alkali metal compounds used as catalysts include sodium hydroxide, potassium hydroxide, and alkali metal alkoxides. Examples of alkali metal alkoxides include lithium methoxide, lithium ethoxide, sodium methoxide, sodium methoxide, sodium ethoxide, potassium methoxide, and potassium ethoxide. Among these, alkali metal compounds are highly active, allowing for economical operation at low catalyst concentrations. Therefore, sodium-containing compounds are preferred, more preferably sodium methoxide or sodium ethoxide, and even more preferably sodium methoxide.

[0023] The concentration of the alkali metal compound is preferably 1 mass ppm to 30,000 mass ppm, more preferably 10 mass ppm to 1,000 mass ppm, and even more preferably 25 mass ppm to 500 mass ppm, relative to the total amount of the raw materials.

[0024] (Reactor R) Examples of the reactor R include a stirred reactor and a reactive distillation column. Since the catalyst or its reaction product is likely to precipitate in the reaction step, the reactor R is preferably a stirred reactor.

[0025] As shown in FIG. 1 , the reactor R has a reaction vessel 11. The reaction vessel 11 is provided with a raw material supply unit 12, through which the raw material is supplied. The raw material is the above-mentioned raw material, contains DMC and EtOH, and may contain a catalyst containing an alkali metal compound. The reactor R has a stirrer 13 inside the reaction vessel 11. A withdrawal unit 14 is provided at the bottom of the reaction vessel 11, from which the reaction composition is withdrawn.

[0026] The reaction temperature in the reaction step is preferably 40°C to 150°C, more preferably 50°C to 130°C, and even more preferably 60°C to 120°C.

[0027] The pressure in the reaction step may be, for example, from atmospheric pressure to 1000 kPaG.

[0028] When a stirred reactor is used and raw materials are continuously supplied, it is preferable to withdraw the reaction composition from the stirred reactor. The reaction composition may be withdrawn continuously. The withdrawal rate of the reaction composition is preferably set so as to achieve the above-mentioned residence time in the reactor.

[0029] The production method according to the present embodiment may include an acid addition step of adding an acidic substance having a pKa of 6.0 or less to the reaction composition after the reaction step. By providing the acid addition step, it is possible to deactivate the alkali metal compound remaining in the reaction composition.

[0030] The pKa of the acidic substance is preferably 0.0 to 5.8, more preferably 1.0 to 5.6, and even more preferably 2.0 to 5.4.

[0031] Examples of acidic substances include organic acids. Examples of organic acids include carboxylic acids and sulfonic acids. Examples of carboxylic acids include carboxylic acids having 2 to 30 carbon atoms, more specifically acetic acid, dichloroacetic acid, propionic acid, butanoic acid, hexanoic acid, and oleic acid. Among these acidic substances, at least one selected from the group consisting of carboxylic acids is preferred, and at least one selected from the group consisting of propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, and oleic acid is more preferred.

[0032] The amount of the acidic substance added in the acid addition step is preferably 2.0 to 15.0, more preferably 2.5 to 12.0, and even more preferably 3.0 to 10.0, in terms of the molar ratio of acidic substance / catalyst.

[0033] In the acid addition step, the acidic substance may be added in a stirring tank, or the reaction composition and the acidic substance may be mixed together using a static mixer.

[0034] The production method according to this embodiment may include a solvent addition step of adding a solvent to the reaction composition after the reaction step or after the acid addition step, and before the distillation step A described below. By adding a solvent, the catalyst contained in the reaction composition is dissolved, thereby more significantly suppressing the formation of precipitates in the distillation step A. It is preferable that the solvent addition step dissolves insoluble matter in the reaction composition. In other words, it is preferable to add a solvent in an amount that will dissolve the insoluble matter contained in the reaction composition.

[0035] Here, the solvent to be added preferably has a solubility of 10% by mass or more at 30°C for the alkali metal compound and the reaction product of the alkali metal compound and the acidic substance. This solubility allows the catalyst contained in the reaction composition to be further dissolved, and the formation of precipitates in the distillation step to be more significantly suppressed. The solubility of the solvent for the alkali metal compound and the reaction product of the alkali metal compound and the acidic substance at 30°C is more preferably 10% by mass or more, and even more preferably 15% by mass or more. The solubility may be, for example, 50% by mass or less at 30°C.

[0036] Here, the boiling point of the solvent is preferably 136°C or higher, more preferably 140°C to 400°C, and even more preferably 150°C to 300°C under normal pressure.

[0037] Here, the boiling point of the solvent is preferably higher than the boiling point of EMC under normal pressure, more preferably 10°C or more higher than the boiling point of EMC, and even more preferably 20°C or more higher than the boiling point of EMC.

[0038] The solvent added in the solvent addition step preferably contains a compound having at least one hydroxyl group, and more preferably contains a compound having at least two hydroxyl groups. Examples of the solvent include monoethylene glycol, diethylene glycol, triethylene glycol, 1-hexanol, 2-hexanol, 1-heptanol, and 2-heptanol. Among these, monoethylene glycol, diethylene glycol, and triethylene glycol are preferred.

[0039] The content of the compound having at least one hydroxyl group is preferably 50% by mass to 100% by mass, more preferably 70% by mass to 100% by mass, and even more preferably 90% by mass to 100% by mass, based on the total amount of the solvent.

[0040] The amount of solvent added in the solvent addition step is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1.0 to 10 parts by mass, relative to 100 parts by mass of the reaction composition, from the viewpoint of more significantly suppressing the formation of precipitates in the distillation step and from the viewpoint of reducing the operating load of the distillation column.

[0041] In the solvent addition step, the solvent may be added in a stirring tank, or the reaction composition and the solvent may be joined together and then mixed using a static mixer.

[0042] <Distillation Step A> In the distillation step A, a feed containing DMC, EMC, and EtOH is supplied to a distillation column A, and a fraction A is obtained from the bottom of the distillation column A. Ｂ The feed may be the reaction composition obtained in the above-mentioned reaction step, or may be a mixture containing the reaction composition and recycled components such as other fractions.

[0043] The feed contains DMC in a proportion of at least 15 mol % based on the total feed amount and EMC in a proportion of at least 12 mol % based on the total feed amount.

[0044] By containing DMC in this ratio, the azeotropic distillation effect with EtOH in distillation column A eliminates the formation of an azeotropic composition of EMC and EtOH, and EtOH can be removed by distillation even at normal pressure, making it possible to produce EMC with low ethanol and methanol contents with high efficiency.

[0045] From the viewpoint of more efficiently producing EMC with low ethanol and methanol contents, the proportion of DMC is preferably 15 mol% to 60 mol%, more preferably 20 mol% to 50 mol%, and even more preferably 25 mol% to 40 mol% relative to the total amount of feed. When the proportion of DMC is equal to or greater than the lower limit, the azeotropic action of DMC and EtOH described above allows alcohol to be separated even by distillation at normal pressure. Furthermore, when the proportion of DMC is equal to or less than the upper limit, the amount of DMC introduced into the distillation column can be reduced, thereby enabling EMC to be purified more efficiently.

[0046] From the viewpoint of more efficiently producing EMC with low ethanol and methanol contents, the proportion of EMC is preferably 12 mol% to 50 mol%, more preferably 15 mol% to 40 mol%, and even more preferably 17 mol% to 30 mol%, based on the total amount of feed. When the proportion of EMC is equal to or greater than the lower limit, a sufficient amount of EMC can be introduced into distillation column A, thereby enabling more efficient purification of EMC. Note that when the proportion of EMC is equal to or less than the upper limit, alcohol can be separated even by distillation at normal pressure due to the azeotropic action of DMC and EtOH described above.

[0047] The molar ratio of dimethyl carbonate / (ethanol + ethyl methyl carbonate) in the feed is 0.1 to 2.0. This ratio eliminates the formation of an azeotropic composition of EMC and EtOH due to the azeotropic distillation effect of DMC and EtOH in distillation column A, and ethanol can be removed from EMC by distillation even at atmospheric pressure, making it possible to produce EMC with low ethanol and methanol contents with high efficiency. The molar ratio of DMC / (EtOH + EMC) is preferably 0.3 to 1.6, more preferably 0.4 to 1.5, and even more preferably 0.5 to 1.4.

[0048] The DMC / EMC molar ratio is preferably 0.8 to 2.5, more preferably 0.9 to 2.3, and even more preferably 1.0 to 2.1, from the viewpoint of eliminating the azeotropy between EMC and ethanol and more efficiently producing EMC having a low ethanol and methanol content.

[0049] From the viewpoint of more efficiently producing EMC having a low content of ethanol and methanol, the proportion of EtOH in the feed is preferably 5 mol% to 40 mol%, more preferably 7 mol% to 30 mol%, and even more preferably 9 mol% to 25 mol%, based on the total amount of the feed.

[0050] From the viewpoint of more efficiently producing EMC having a low content of ethanol and methanol, the proportion of MeOH in the feed is preferably 5 mol % to 50 mol %, more preferably 10 mol % to 40 mol %, and even more preferably 15 mol % to 35 mol %, based on the total amount of the feed.

[0051] From the viewpoint of more efficiently producing EMC having a low content of ethanol and methanol, the proportion of DEC in the feed is preferably 0.1 mol % to 20 mol %, more preferably 0.5 mol % to 15 mol %, and even more preferably 1.0 mol % to 10 mol %, based on the total amount of the feed.

[0052] In the above ratios, the total amount of feed is a ratio relative to the total molar amount of MeOH, EtOH, DMC, EMC, and DEC. If the solvent added in the solvent addition step is a solvent other than MeOH, EtOH, DMC, EMC, and DEC, it is excluded from the total amount of feed.

[0053] The various components contained in the feed may be biomass-derived compounds, such as bioethanol, biomethanol, and EMC, DMC, and DEC obtained from at least one selected from the group consisting of bioethanol and biomethanol.

[0054] The method for supplying the feed to distillation column A may be to supply the reaction composition obtained in the reaction step as is, or to supply DMC separately together with the reaction composition. Of the feeds, the method for supplying at least a portion of DMC to distillation column A is preferably by liquid addition alone using a pump.

[0055] Although there are no particular limitations on the distillation column A, for example, a continuous distillation column can be used. The distillation column A is usually equipped with a reboiler for heating the bottom of the column.

[0056] Distillation column A preferably includes trays and / or packings as internals. Internals refer to the portions of the distillation column where gas and liquid actually come into contact. Examples of trays include bubble trays, sieve trays, ripple trays, ballast trays, valve trays, countercurrent trays, Unifrax trays, Superfrac trays, Maxfrac trays, Dual Flow trays, grid plate trays, turbogrid plate trays, and Kittel trays. Examples of packings include random packings such as Raschig rings, Lessing rings, Pall rings, Berl saddles, Intalox saddles, Dixon packing, McMahon packing, and Helipack, and structured packings such as Melapak, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, and Glitchgrid.

[0057] The number of theoretical plates is a numerical value that represents the separation capacity of a distillation column. The number of theoretical plates of a distillation column is preferably 13 or more, preferably 22 or more, more preferably 25 or more, and even more preferably 30 or more. By using a distillation column having a number of theoretical plates in this range, high-purity EMC can be purified with high efficiency. The internals of the distillation column may be trays or packings. The material of the internals is not particularly limited and may be made of porcelain or metal.

[0058] The feed may be introduced into the middle of distillation column A. The "middle of the column" refers to a part of the distillation column excluding the top and bottom. When distillation column A is equipped with internals, the feed is preferably introduced into the middle of the column from a position above ½ and below ⅙ of the total length of the packed internals.

[0059] The temperature of the feed is preferably 25°C to 100°C, more preferably 30°C to 90°C, and even more preferably 35°C to 80°C.

[0060] The bottom temperature of distillation column A is preferably 80° C. to 250° C., more preferably 90° C. to 200° C., even more preferably 100° C. to 150° C., and still more preferably 105° C. to 120° C. When the bottom temperature of distillation column A is within this range, EMC with low ethanol and methanol contents can be produced with high energy efficiency.

[0061] The top pressure of distillation column A is preferably 0 kPaG to 50 kPaG, more preferably 0 kPaG to 30 kPaG, and even more preferably 0 kPaG to 20 kPaG. In this embodiment, by containing DMC in a predetermined range in the feed, alcohol can be removed by distillation even at a top pressure within that range, and EMC with low ethanol and methanol contents can be produced with high energy efficiency.

[0062] The bottom pressure of the distillation column A is preferably 0.5 kPaG to 80 kPaG, more preferably 1 kPaG to 60 kPaG, and even more preferably 2 kPaG to 40 kPaG.

[0063] The reflux ratio of the distillation column A is preferably 0.3 to 20, more preferably 0.5 to 15, and even more preferably 0.7 to 5.

[0064] In distillation column A, the feed is distilled, and fraction A is obtained from the bottom of the column. Ｂ is extracted, and fraction A is extracted from the top. Ｌ Fraction A is extracted. Ｌ may be withdrawn from the top of the column.

[0065] Fraction A obtained by distillation step A Ｂ The ratio of ethanol to ethyl methyl carbonate in the fraction A is 20 mass ppm or less, and Ｂ The ratio of methanol to ethyl methyl carbonate in the distillation step A is 20 mass ppm or less. In the distillation step A, the distillation conditions are adjusted so as to achieve the alcohol content ratio. As for the distillation conditions, if the feed contains DMC within a predetermined range, it is possible to adjust the distillation conditions so as to achieve the ethanol and methanol ratio by adjusting the column bottom temperature, etc. Ｂ The ratio of ethanol to EMC in the fraction A is preferably 17 ppm by mass or less, more preferably 15 ppm by mass or less, and even more preferably 10 ppm by mass or less. Ｂ The ratio of methanol to EMC in the mixture is preferably 17 mass ppm or less, more preferably 15 mass ppm or less, and even more preferably 10 mass ppm or less.

[0066] From the viewpoint of reducing the amount of energy consumed in the distillation step A while suppressing the loss of EMC, fraction A Ｌ The EMC content in the fraction A is preferably 0.5% by mass to 10% by mass, more preferably 0.7% by mass to 8% by mass, and even more preferably 1.0% by mass to 7% by mass. Ｌ It is preferable to carry out the distillation by adjusting the temperature and pressure so that the EMC content in the distillation liquid falls within the above range.

[0067] Similarly, from the viewpoint of reducing the amount of energy consumed in the distillation step A while suppressing the loss of EMC, fraction A ＢThe DMC content in the fraction A is preferably 0.001% by mass to 5.0% by mass, more preferably 0.0015% by mass to 4.0% by mass, and even more preferably 0.002% by mass to 3.5% by mass. Ｌ It is preferable to carry out the distillation by adjusting the temperature and pressure so that the EMC content in the distillation liquid falls within the above range.

[0068] As described above, according to the distillation step A, it is possible to produce EMC with low contents of ethanol and methanol with high efficiency. By further distilling the obtained fraction, it is possible to obtain high-purity EMC with high efficiency.

[0069] Further, methods for producing high-purity EMC include the following (1), (2), and (3): (1) Fraction A Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ a distillation step B for extracting the fraction B; Ｂ is supplied to a distillation column C, and fraction C is extracted from the top of the distillation column C. Ｌ The method further comprises a distillation step C for extracting the fraction C. Ｌ (2) the purity of ethyl methyl carbonate in the fraction A is 99.99% by mass or more; or Ｂ is supplied to a distillation column D, and fraction D is obtained from the bottom of the distillation column D. Ｂ From the top of the column, fraction D Ｌ From the middle of the distillation column D, fraction D Ｓ The method further comprises a distillation step D for extracting the fraction D. Ｓ (3) the purity of ethyl methyl carbonate in the fraction A is 99.99% by mass or more; or Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ a distillation step B for extracting the fraction B; Ｂ is supplied to a distillation column D, and fraction D is obtained from the bottom of the distillation column D. Ｂ From the top of the column, fraction D Ｌ From the middle of the distillation column D, fraction D ＳThe method further comprises a distillation step D for extracting the fraction D. Ｓ The purity of ethyl methyl carbonate in the mixture is 99.99% by mass or more.

[0070] <Distillation Step B> In the method for producing EMC according to this embodiment, fraction A Ｂ is supplied to a distillation column B, and a fraction B from the bottom of the distillation column B is obtained by removing low-boiling substances having a boiling point lower than that of ethyl methyl carbonate. Ｂ In the distillation step B, fraction A is extracted. Ｂ The low boiling point substances having a boiling point lower than that of ethyl methyl carbonate, such as DMC, contained in the fraction A are removed. Note that the removal of the low boiling point substances does not necessarily mean that the low boiling point substances have been completely removed, and the removal of the low boiling point substances from the fraction A is not necessarily required. Ｂ The content of the low boiling point substance in fraction B is Ｂ It is sufficient that the content of the low boiling point substance in the liquid is lower than the content of the low boiling point substance in the liquid.

[0071] The distillation column B used in the distillation step B may be the same as that exemplified for the distillation column A. The number of theoretical plates of the distillation column B is preferably 30 or more, more preferably 35 or more, and even more preferably 40 or more. By using a distillation column having a number of theoretical plates in this range, impurities other than ethanol and / or methanol (e.g., DMC) can be further removed, thereby increasing the purity of the EMC. The internals of the distillation column may be trays or packings. In addition, the material of the internals is not particularly limited and may be made of porcelain, metal, or the like.

[0072] Fraction A Ｂ may be introduced from the middle of distillation column B. When distillation column B is equipped with an internal, the internal is preferably introduced at a position above ¼ and below 5 / 6 of the total length of the packed internal.

[0073] The bottom temperature of distillation column B is preferably 80°C to 250°C, more preferably 90°C to 200°C, even more preferably 100°C to 150°C, and still more preferably 105°C to 120°C.

[0074] The pressure at the top of the distillation column B is preferably 0 kPaG to 50 kPaG, more preferably 0 kPaG to 30 kPaG, and even more preferably 0 kPaG to 20 kPaG.

[0075] The bottom pressure of distillation column B is preferably 0.5 kPaG to 80 kPaG, more preferably 1 kPaG to 60 kPaG, and even more preferably 2 kPaG to 40 kPaG.

[0076] The reflux ratio of distillation column B is preferably 5 to 1,500, more preferably 10 to 1,400, and even more preferably 15 to 1,350.

[0077] Fraction B Ｂ The purity of EMC in fraction B is preferably 50% by mass to 90% by mass, more preferably 60% by mass to 90% by mass, and even more preferably 70% by mass to 90% by mass. Ｂ The DMC content therein is preferably 50 ppm by mass or less, more preferably 20 ppm by mass or less, even more preferably 17 ppm by mass or less, and even more preferably 15 ppm by mass or less.

[0078] Fraction B Ｌ The DMC content in the ethanol and / or methanol is preferably 5.0% to 98% by mass, more preferably 10% to 98% by mass, and even more preferably 13% to 98% by mass. By setting the DMC content in this range, impurities other than ethanol and / or methanol (e.g., DMC) can be reduced, and the EMC purity can be increased.

[0079] <Distillation Step C> In the method for producing EMC according to this embodiment, fraction B Ｂ is supplied to a distillation column C, and fraction C is extracted from the top of the distillation column C. Ｌ In the distillation step C, fraction B is extracted. Ｂ Components with a higher boiling point than EMC, such as DEC, contained therein are removed.

[0080] The distillation column C used in the distillation step C may be the same as that exemplified for the distillation column A. The number of theoretical plates of the distillation column is preferably 30 or more, more preferably 35 or more, and even more preferably 40 or more. Impurities other than ethanol and / or methanol (e.g., DMC) can be reduced, and the EMC purity can be increased. The internals of the distillation column may be trays or packings. In addition, the material of the internals is not particularly limited and may be made of porcelain, metal, or the like.

[0081] Fraction B Ｂ The fraction B may be introduced from the middle of the distillation column C. When the distillation column C is equipped with an internal, the fraction B is preferably introduced from the middle of the distillation column C at a position above 1 / 4 and below 5 / 6 of the total length of the internal packed therein. Ｂ The fraction C is fed from the feed position Ｌ It is preferable that the withdrawal position of fraction C is at the top. Both the supply and withdrawal may be provided in the middle of the column, and in this case, the withdrawal section should be arranged relatively higher than the supply section. Ｌ The upper part of the column from which fraction C is extracted means a position between 5 / 6 and the top of the column from the bottom of the packing. The extraction position is preferably the upper part. Ｌ may be withdrawn from the top of the tower or may be side-cut at a position 5 / 6 or more from the bottom.

[0082] The bottom temperature of distillation column C is preferably 80°C to 250°C, more preferably 90°C to 200°C, even more preferably 100°C to 180°C, and still more preferably 105°C to 150°C.

[0083] The pressure at the top of the distillation column C is preferably 0 kPaG to 50 kPaG, more preferably 0 kPaG to 30 kPaG, and even more preferably 0 kPaG to 20 kPaG.

[0084] The bottom pressure of the distillation column C is preferably 0.5 kPaG to 80 kPaG, more preferably 1 kPaG to 60 kPaG, and even more preferably 2 kPaG to 40 kPaG.

[0085] The reflux ratio of the distillation column C is preferably 0.8 to 20, more preferably 1.2 to 15, and even more preferably 1.5 to 10.

[0086] Distillate C Ｂ The EMC content in the fraction C is preferably 0.1% by mass to 5.0% by mass, more preferably 0.2% by mass to 4.0% by mass, and even more preferably 0.25% by mass to 3.5% by mass. By adjusting the content within such a range, high-purity EMC can be purified with high efficiency. Ｌ The DEC content therein is preferably 1 ppm by mass to 50 ppm by mass, more preferably 1 ppm by mass to 45 ppm by mass, and even more preferably 1 ppm by mass to 40 ppm by mass.

[0087] Distillate C L may be the EMC of the final target.

[0088] <Distillation Step D> In the method for producing EMC according to this embodiment, fraction A Ｂ or fraction B Ｂ is fed to a distillation column D, and fraction D is obtained from the bottom of the distillation column D. Ｂ From the top of the column, fraction D Ｌ From the middle of the distillation column D, fraction D Ｓ For example, instead of the distillation steps B and C, the distillation step D may be provided, whereby the product may be withdrawn through a middle portion (side cut) of the distillation step D and separated from low-boiling and high-boiling components.

[0089] That is, in the distillation step D, fraction A Ｂ The components with a boiling point lower than EMC, such as DMC, contained in the Ｌ and components with a boiling point higher than EMC, such as DEC, are separated into fraction D. Ｂ More removal.

[0090] The distillation column D used in the distillation step D may be the same as that exemplified for the distillation column A. The bottom temperature of the distillation column D is preferably 80°C to 250°C, more preferably 90°C to 200°C, even more preferably 100°C to 180°C, and still more preferably 105°C to 150°C.

[0091] The pressure at the top of the distillation column D is preferably 0 kPaG to 50 kPaG, more preferably 0 kPaG to 30 kPaG, and even more preferably 0 kPaG to 20 kPaG.

[0092] The bottom pressure of the distillation column D is preferably 0.5 kPaG to 80 kPaG, more preferably 1 kPaG to 60 kPaG, and even more preferably 2 kPaG to 40 kPaG.

[0093] The reflux ratio of distillation column D is preferably 5 to 1,500, more preferably 10 to 1,400, and even more preferably 15 to 1,350.

[0094] Fraction D Ｂ The EMC content in the pulp is preferably 0.1% by mass to 5.0% by mass, more preferably 0.2% by mass to 4.0% by mass, and even more preferably 0.25% by mass to 3.5% by mass. By setting the content in such a range, high-purity EMC can be purified with high efficiency.

[0095] Fraction D Ｌ The DMC content therein is preferably 1.5% by mass to 20% by mass, more preferably 1.0% by mass to 30% by mass, and even more preferably 2.0% by mass to 15% by mass.

[0096] High-purity EMC can be purified with high efficiency.

[0097] In the method for producing EMC according to this embodiment, the fraction C extracted from the bottom of the distillation column C or the distillation column D is Ｂ or fraction D Ｂ The method may further include a step of distilling the diethyl carbonate to obtain diethyl carbonate having a purity of 99.99% by mass or more. Examples of the step include a step of purifying diethyl carbonate, such as distillation step E or distillation step F.

[0098] <Distillation Step E> In the method for producing EMC according to this embodiment, fraction C Ｂ or fraction D Ｂ is supplied to a distillation column E, and a fraction E from the bottom of the distillation column E, from which low-boiling substances having a boiling point lower than the boiling point of diethyl carbonate have been removed, is obtained. ＢIn the distillation step E, fraction C is extracted. Ｂ or fraction D Ｂ The low boiling point substances such as EMC contained in the fraction C, which have a boiling point lower than that of diethyl carbonate, are removed. Note that the removal of the low boiling point substances does not necessarily mean that the low boiling point substances have been completely removed, and the removal of the low boiling point substances from the fraction C is not necessarily required. Ｂ or fraction D Ｂ The content of the low boiling point substance in fraction E Ｂ It is sufficient that the content of the low boiling point substance in the liquid is lower than the content of the low boiling point substance in the liquid.

[0099] The distillation column E used in the distillation step E may be the same as that exemplified for the distillation column A. Furthermore, a distillation column having 15 or more theoretical plates as a separation capacity is preferred, more preferably 20 or more, and even more preferably 25 or more, which allows for further removal of low-boiling substances (e.g., EMC) having a boiling point lower than that of diethyl carbonate, thereby increasing the purity of DEC. As long as the distillation column has this capacity, the internals may be trays or packings. Additionally, the material of the internals is not particularly limited, and may be made of porcelain, metal, or the like.

[0100] Distillate C Ｂ or fraction D Ｂ may be introduced from the middle of the distillation column E. In addition, when the distillation column E is equipped with an internal, the internal is preferably introduced at a position above ¼ and below 5 / 6 of the total length of the packed internal.

[0101] The bottom temperature of distillation column E is preferably 90°C to 250°C, more preferably 100°C to 200°C, even more preferably 105°C to 150°C, and still more preferably 110°C to 140°C.

[0102] The pressure at the top of the distillation column E is preferably 0 kPaG to 50 kPaG, more preferably 0 kPaG to 30 kPaG, and even more preferably 0 kPaG to 20 kPaG.

[0103] The bottom pressure of the distillation column E is preferably 0.5 kPaG to 80 kPaG, more preferably 1 kPaG to 60 kPaG, and even more preferably 2 kPaG to 40 kPaG.

[0104] The reflux ratio of distillation column E is preferably 5 to 2,000, more preferably 7.5 to 1,800, and even more preferably 9.0 to 1,600.

[0105] Fraction E Ｂ The purity of DEC therein is preferably 99% by mass to 99.9995% by mass, more preferably 99.9% by mass to 99.999% by mass, and even more preferably 99.99% by mass to 99.998% by mass.

[0106] Fraction E Ｂ The content of EMC therein is preferably 50 ppm by mass or less, more preferably 40 ppm by mass or less, more preferably 30 ppm by mass or less, and even more preferably 15 ppm by mass or less.

[0107] Fraction E Ｌ The DEC content in the diethyl carbonate is preferably 0.001% by mass to 90% by mass, more preferably 0.002% by mass to 80% by mass, and even more preferably 0.01% by mass to 70% by mass. By adjusting the content to such a range, it is possible to reduce low-boiling substances (e.g., EMC) having a boiling point lower than that of diethyl carbonate and increase the DEC purity.

[0108] <Distillation Step F> In the method for producing EMC according to this embodiment, fraction C Ｂ or fraction D Ｂ is fed to distillation column F, and fraction F is obtained from the bottom of distillation column F. Ｂ From the top of the column, fraction F Ｌ From the middle of distillation column F, fraction F Ｓ For example, by providing distillation step F instead of distillation step E, a product may be extracted from the middle (side cut) of distillation step F and separated into low boiling points and high boiling points. Ｂ or fraction D Ｂ The components with lower boiling points than DEC, such as EMC, are separated into fraction F. Ｌ and components with higher boiling points than DEC are removed by F Ｂ The distillation column F used in the distillation step F may be the same as the distillation column A.

[0109] The bottom temperature of distillation column F is preferably 90°C to 250°C, more preferably 100°C to 200°C, even more preferably 105°C to 150°C, and still more preferably 110°C to 140°C.

[0110] The pressure at the top of the distillation column F is preferably 0 kPaG to 50 kPaG, more preferably 0 kPaG to 30 kPaG, and even more preferably 0 kPaG to 20 kPaG.

[0111] The bottom pressure of the distillation column F is preferably 0.5 kPaG to 80 kPaG, more preferably 1 kPaG to 60 kPaG, and even more preferably 2 kPaG to 40 kPaG.

[0112] The reflux ratio of distillation column F is preferably 5 to 2,000, more preferably 7.5 to 1,800, and even more preferably 9.0 to 1,600.

[0113] Fraction F Ｂ The DEC content in the olefin copolymer is preferably 30% by mass to 99% by mass, more preferably 40% by mass to 98% by mass, and even more preferably 50% by mass to 95% by mass. By adjusting the content within this range, highly pure DEC can be purified with high efficiency.

[0114] Fraction F Ｌ The DEC content therein is preferably 0.001% by mass to 90% by mass, more preferably 0.002% by mass to 80% by mass, and even more preferably 0.01% by mass to 70% by mass.

[0115] The purity of the EMC obtained by the production method according to this embodiment is preferably 99% by mass or more, more preferably 99.9% by mass or more, and even more preferably 99.99% by mass or more.

[0116] The content of EtOH in the EMC product obtained by the production method according to this embodiment is preferably 20 ppm by mass or less, more preferably 17 ppm by mass or less, and even more preferably 15 ppm by mass or less.

[0117] The content of MeOH in each of the EMC products obtained by the production method according to this embodiment is preferably 20 ppm by mass or less, more preferably 17 ppm by mass or less, and even more preferably 15 ppm by mass or less.

[0118] The DMC content in the EMC product obtained by the production method according to this embodiment is preferably 20 ppm by mass or less, more preferably 17 ppm by mass or less, and even more preferably 15 ppm by mass or less.

[0119] The purity and analysis of each major component in EMC products are measured by gas chromatography. Gas chromatography analysis is performed in accordance with HG / T 5158-2017.

[0120] The manufacturing equipment used in the manufacturing method for EMC according to this embodiment and the combination of each process when using this manufacturing equipment will be described below.

[0121] 1 is a schematic diagram of a production facility used in the method for producing EMC according to this embodiment. The production facility may include a reaction apparatus R, a distillation column A, a distillation column B, and a distillation column C. When this production facility is used, the method for producing EMC according to this embodiment includes a reaction step R, a distillation step A, a distillation step B, and a distillation step C in this order.

[0122] 2 is a schematic diagram of a production facility used in the method for producing EMC according to this embodiment. The production facility may include a reaction apparatus R, a distillation column A, and a distillation column D. When using this production facility, the method for producing EMC according to this embodiment includes a reaction step R, a distillation step A, and a distillation step D in this order. By this production method, fraction A is obtained. Ｂ Since both the high-boiling point component and the low-boiling point component contained in the distillation step D can be simultaneously removed in the distillation step D, the number of distillation steps and the number of distillation columns in the equipment can be reduced.

[0123] 3 is a schematic diagram of a production facility used in the EMC production method according to this embodiment. The production facility according to this embodiment may include a reaction apparatus R, a distillation column A, a distillation column B, a distillation column C, and a distillation column F. When this production facility is used, the EMC production method according to this embodiment includes, in this order, a reaction step R, a distillation step A, a distillation step B, a distillation step C, and a distillation step F. By including the distillation step F, not only EMC but also DEC can be recovered as a product.

[0124] 4 is a schematic diagram of a production facility used in the EMC production method according to this embodiment. The production facility according to this embodiment may include a reaction apparatus R, a distillation column A, a distillation column D, and a distillation column E. When this production facility is used, the EMC production method according to this embodiment includes, in this order, a reaction step R, a distillation step A, a distillation step D, and a distillation step E. By including the distillation step E, not only EMC but also DEC can be recovered as a product.

[0125] 5 is a schematic diagram of a production facility used in the method for producing EMC according to this embodiment. The production facility may include a reaction apparatus R, a distillation column A, a distillation column B, and a distillation column D. When this production facility is used, the method for producing EMC according to this embodiment includes a reaction step R, a distillation step A, a distillation step B, and a distillation step D in this order. By this production method, fraction B Ｂ Since both the high-boiling point component and the low-boiling point component contained in the distillation step D can be simultaneously removed, it is possible to obtain EMC with higher purity.

[0126] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[0127] [Example 1] A method for producing ethyl methyl carbonate was carried out using the apparatus shown in Figure 1. DMC 475.2 kg / h (5.28 kmol / h), EtOH 210.7 kg / h (4.58 kmol / h), and a 3.2 mass% (1.9 mol%) methanol solution of sodium methoxide were supplied to a stirred tank reactor with a capacity of 1.5 m3 at a flow rate of 4.3 kg / h (0.13 kmol / h), reacted under conditions of 50 ° C. and 103 kPaG, and extracted from the stirred tank reactor at 690 kg / h (9.99 kmol / h), to obtain a reaction composition containing EMC. After filtration, the reaction composition was supplied to a stirred tank holding 20 kg of solid adsorbent, stirred for 1 hour, filtered, and supplied to distillation column A and distilled as described below.

[0128] EMC was purified in a carbon steel distillation column having 60 perforated trays as follows. The distillation column had a separation capacity of 39 theoretical plates.

[0129] MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.93 kmol / h, EMC 1.98 kmol / h, and DEC 0.37 kmol / h were supplied as a liquid at 50 ° C. on the 46th tray from the bottom of the distillation column. The DMC concentration in the feed liquid was 29.3 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.76. Distillation column A was operated continuously at a column top pressure of 0.0 kPaG, a column bottom pressure of 3.1 kPaG, a column bottom temperature of 109.2 ° C., and a reflux ratio of 1.7.

[0130] A liquid was continuously extracted from the bottom of distillation column A at a rate of 2.36 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction A) Ｂ The distillation column A was continuously pumped out at a rate of 7.63 kmol / h from the top of the column A. ... Ｌ) was MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.92 kmol / h, EMC 0.001 kmol / h.

[0131] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was fed to distillation column B and distilled as described below.

[0132] Distillation column B was made of SUS304 and had 27 m of structured packing MellaPak752Y, and EMC was purified as follows: The separation capacity of the distillation column was 48 theoretical plates.

[0133] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was supplied as a liquid at 107°C to a position 13.0 m from the bottom of the packing of distillation column B. Distillation column B was operated at a column top pressure of -40.0 kPaG, a column bottom pressure of -37.9 kPaG, a column bottom temperature of 93.7°C, and a reflux ratio of 1,100.

[0134] A liquid was continuously extracted from the bottom of distillation column B at a rate of 2.35 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction B) Ｂ The distillation column B had a DMC content of 0.0001 kmol / h, EMC content of 1.98 kmol / h, and DEC content of 0.37 kmol / h. The DMC content in the bottom liquid was 25 ppm by mass, achieving a DMC content of 50 ppm by mass or less. Furthermore, a liquid was continuously extracted from the top of the distillation column B at a rate of 0.01 kmol / h using a pump. The liquid extracted from the top of the column (fraction B Ｌ ) was DMC 0.01 kmol / h, EMC 0.002 kmol / h.

[0135] The liquid extracted from the bottom of distillation column B (fraction B Ｂ ) was fed to distillation column C and distilled as described below.

[0136] Distillation column C was made of SUS316 and had 49 m of structured packing MellaPak250Y, and EMC was purified as follows. The separation capacity of the distillation column was 47 theoretical plates.

[0137] The liquid extracted from the bottom of distillation column B (fraction B Ｂ) was supplied as a liquid at 93°C to a position 14.0 m from the bottom of the packing of the distillation column. The distillation column was operated at a column top pressure of 0.0 kPaG, a column bottom pressure of 2.1 kPaG, a column bottom temperature of 127.5°C, and a reflux ratio of 2.0.

[0138] A liquid was continuously extracted from the bottom of distillation column C at a rate of 0.43 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction C) Ｂ The EMC content in the bottom liquid was 11.9 mass%. A liquid was continuously extracted from the top of the distillation column at a rate of 1.92 kmol / h by a pump. The liquid extracted from the top of the column (fraction C) Ｌ ) DMC 0.00007 kmol / h, EMC 1.92 kmol / h, DEC 0.00008 kmol / h, and EMC purification with a purity of 99.99 mass% or more was achieved.

[0139] Example 2 A method for producing ethyl methyl carbonate was carried out using the apparatus shown in Figure 2. Distillation column A was a distillation column made of SUS304 and equipped with 19 m of structured packing, MellaPak 752Y, and EMC was purified as follows. The separation capacity of the distillation column was 47 theoretical plates.

[0140] MeOH 3.33 kmol / h, EtOH 1.74 kmol / h, DMC 3.67 kmol / h, EMC 2.08 kmol / h, and DEC 0.26 kmol / h were supplied as a liquid at 50 ° C. to a portion 12.7 m from the bottom of the packing of the distillation column. Similarly, DMC 0.408 kmol / h was supplied as a liquid at 50 ° C. to a portion 12.7 m from the bottom of the packing of the distillation column. The DMC concentration in the feed liquid was 4.3 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.11. Distillation column A was continuously operated at a column top pressure of 2.3 kPaG, a column bottom pressure of 3.8 kPaG, a column bottom temperature of 107.8 ° C., and a reflux ratio of 1.0.

[0141] A liquid was continuously extracted from the bottom of distillation column A at a rate of 2.38 kmol / h by a pump. The liquid extracted from the bottom of the column (fraction A) ＢThe total amount of ethanol and methanol relative to the mass of EMC in the bottom liquid was 0 ppm by mass, achieving a concentration of 20 ppm by mass or less. Ｌ The liquid withdrawn from the top of the column was 3.33 kmol / h of MeOH, 1.74 kmol / h of EtOH, 3.61 kmol / h of DMC, and 0.018 kmol / h of EMC.

[0142] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was fed to distillation column D and distilled as described below.

[0143] Distillation column D was made of SUS304 and had 47 m of structured packing MellaPak752Y, and EMC was purified as follows. The separation capacity of the distillation column was 47 theoretical plates.

[0144] A gaseous fraction was continuously extracted at a rate of 1.92 kmol / h from the portion 26 m from the bottom of the packing of distillation column D, condensed in a condenser, and then continuously extracted as a side cut by a pump. The liquid extracted from the side cut (fraction D Ｓ The distillation column D was supplied with 0.39 kmol / h of liquid (fraction D) from the bottom of the distillation column D. Ｂ The liquid (fraction D) extracted from the bottom of the column was continuously extracted by a pump. Ｂ The distillation column D was further supplied with a liquid (fraction D) at a rate of 0.062 kmol / h from the top of the column. Ｌ The liquid (fraction D) extracted from the top of the column was continuously extracted by a pump. Ｌ ) was DMC 0.06 kmol / h, EMC 0.002 kmol / h.

[0145] Example 3 A method for producing ethyl methyl carbonate was carried out using the apparatus shown in Figure 1. Distillation column A was made of carbon steel and had 20 perforated trays, and EMC was purified as follows. The separation capacity of the distillation column was 13 theoretical plates.

[0146] MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.93 kmol / h, EMC 1.98 kmol / h, and DEC 0.37 kmol / h were supplied as a liquid at 50 ° C. onto the eighth tray from the bottom of distillation column A. The DMC concentration in the feed liquid was 29.3 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.76. Distillation column A was continuously operated at a column top pressure of 0.0 kPaG, a column bottom pressure of 1.0 kPaG, a column bottom temperature of 105.7 ° C., and a reflux ratio of 2.0.

[0147] From the bottom of distillation column A, a liquid (fraction A) was obtained at a rate of 2.60 kmol / h. Ｂ The liquid (fraction A) extracted from the bottom of the column was continuously extracted by a pump. Ｂ The total amount of ethanol and methanol relative to the mass of EMC in the bottom liquid was 1 ppm by mass, achieving a concentration of 20 ppm by mass or less. In addition, a liquid (fraction A) was obtained from the top of the distillation column at a rate of 7.39 kmol / h. Ｌ The liquid (fraction A) extracted from the top of the column was continuously extracted by a pump. Ｌ ) was MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.59 kmol / h, EMC 0.093 kmol / h.

[0148] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was fed to distillation column B and distilled as described below.

[0149] Distillation column B was made of SUS304 and had 27 m of structured packing MellaPak752Y, and EMC was purified as follows: The separation capacity of the distillation column was 48 theoretical plates.

[0150] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was supplied as a liquid at 107°C to a position 13.0 m from the bottom of the packing of the distillation column. Distillation column B was operated at a column top pressure of -40.0 kPaG, a column bottom pressure of -37.9 kPaG, a column bottom temperature of 93.7°C, and a reflux ratio of 20.

[0151] From the bottom of distillation column B, a liquid (fraction B) of 2.26 kmol / h was obtained. Ｂ The liquid (fraction B) extracted from the bottom of the column was continuously extracted by a pump. Ｂ The DMC content in the bottom liquid was 47 ppm by mass, achieving a level of 50 ppm by mass or less. Ｌ The liquid (fraction B) extracted from the top of the column was continuously extracted by a pump. Ｌ ) was DMC 0.34 kmol / h, EMC 0.001 kmol / h.

[0152] The liquid extracted from the bottom of distillation column B (fraction B Ｂ ) was fed to distillation column C and distilled as described below.

[0153] Distillation column C was made of SUS316 and had 49 m of structured packing MellaPak250Y, and EMC was purified as follows. The separation capacity of the distillation column was 47 theoretical plates.

[0154] The liquid extracted from the bottom of distillation column B (fraction B Ｂ ) was supplied as a liquid at 93°C to a position 14.0 m from the bottom of the packing of distillation column C. The distillation column was operated at a column top pressure of 0.0 kPaG, a column bottom pressure of 2.1 kPaG, a column bottom temperature of 127.5°C, and a reflux ratio of 2.0.

[0155] A liquid was continuously extracted from the bottom of distillation column C at a rate of 0.38 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction C) Ｂ The EMC content in the bottom liquid was 1.5 mass %. A 1.88 kmol / h liquid (fraction C) was obtained from the top of distillation column C.Ｌ The liquid (fraction C) extracted from the top of the column was continuously extracted by a pump. Ｌ ) DMC 0.00012 kmol / h, EMC 1.88 kmol / h, DEC 0.00005 kmol / h, and EMC purification with a purity of 99.99 mass% or more was achieved.

[0156] Example 4 A method for producing ethyl methyl carbonate was carried out using the apparatus shown in Figure 2. Distillation column A was a distillation column made of SUS304 and equipped with 19 m of structured packing, MellaPak 752Y, and EMC was purified as follows. The separation capacity of the distillation column was 47 theoretical plates.

[0157] MeOH 3.33 kmol / h, EtOH 1.74 kmol / h, DMC 3.67 kmol / h, EMC 2.08 kmol / h, and DEC 0.26 kmol / h were supplied as a liquid at 50 ° C. to a portion 12.7 m from the bottom of the packing of distillation column A. Similarly, DMC 0.408 kmol / h was supplied as a liquid at 50 ° C. to a portion 12.7 m from the bottom of the packing of the distillation column. The DMC concentration in the feed liquid was 4.3 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.11. The distillation column was continuously operated at a column top pressure of 40.4 kPaG, a column bottom pressure of 42.0 kPaG, a column bottom temperature of 119.2 ° C., and a reflux ratio of 1.2.

[0158] A liquid was continuously extracted from the bottom of distillation column A at a rate of 2.21 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction A) Ｂ The total amount of ethanol and methanol relative to the mass of EMC in the column bottom liquid was 11.7 mass ppm, achieving a level of 20 mass ppm or less. In addition, a liquid (fraction A) of 8.87 kmol / h was obtained from the top of distillation column A. Ｌ The liquid (fraction A) extracted from the top of the column was continuously extracted by a pump. Ｌ) was MeOH 3.33 kmol / h, EtOH 1.74 kmol / h, DMC 3.670 kmol / h, EMC 0.130 kmol / h.

[0159] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was fed to distillation column D and distilled as described below.

[0160] Distillation column D was made of SUS304 and had 47 m of structured packing MellaPak752Y, and EMC was purified as follows. The separation capacity of the distillation column was 84 theoretical plates.

[0161] The gas was continuously extracted at a rate of 1.83 kmol / h from the portion 26 m from the bottom of the packing of distillation column D, condensed in a condenser, and then continuously side-cut by a pump (fraction D Ｓ The liquid extracted from the side cut (fraction D Ｓ The distillation column D was supplied with 0.38 kmol / h of a liquid (fraction D) from the bottom of the distillation column D. Ｂ The liquid (fraction D) extracted from the bottom of the column was continuously extracted by a pump. Ｌ The distillation column had an EMC of 0.12 kmol / h and a DEC of 0.26 kmol / h. Furthermore, a liquid (fraction D) of 0.0019 kmol / h was obtained from the top of the distillation column. Ｔ The liquid (fraction D) extracted from the top of the column was continuously extracted by a pump. Ｔ ) was MtOH 0.000004 kmol / h, EtOH 0.00001 kmol / h, EMC 0.002 kmol / h.

[0162] Example 5 A method for producing ethyl methyl carbonate was carried out using the apparatus shown in Figure 3. The operating conditions and flow rates of distillation columns A, B, and C were the same as those in Example 1. The liquid extracted from the bottom of distillation column C (fraction C) was Ｂ ) was fed to distillation column F and distilled as described below.

[0163] Distillation column F was made of SUS304 and had 46 m of structured packing MellaPak250Y, and DEC was purified as follows: The separation capacity of the distillation column was 50 theoretical plates.

[0164] The gas was continuously extracted at a rate of 0.37 kmol / h from the portion 22 m from the bottom of the packing of the distillation column F, condensed in a condenser, and then continuously side-cut by a pump (fraction F). Ｓ The liquid extracted from the side cut (fraction F) Ｓ The distillation column F had a distillation efficiency of 0.00002 kmol / h and a distillation efficiency of 0.37 kmol / h, achieving a distillation efficiency of 99.99% by mass or higher. Ｂ The liquid (fraction F) extracted from the bottom of the column was continuously extracted by a pump. Ｂ The distillation column F was further supplied with a liquid (fraction F) at a rate of 0.06 kmol / h. Ｌ The liquid (fraction F) extracted from the top of the column was continuously extracted by a pump. Ｌ ) EMC 0.06 kmol / h, DEC 0.00002 kmol / h.

[0165] Example 6 A method for producing ethyl methyl carbonate was carried out using the apparatus shown in FIG. 4. The operating conditions and flow rates of distillation column A and distillation column D were the same as those in Example 2. The liquid extracted from the bottom of distillation column D (fraction D) was Ｂ ) was fed to distillation column E and distilled as described below.

[0166] Distillation column E was made of SUS304 and had 46 m of structured packing MellaPak250Y, and was used to purify DEC as follows: The separation capacity of the distillation column was 50 theoretical plates.

[0167] From the bottom of distillation column E, a liquid (fraction E) of 0.26 kmol / h was obtained. Ｂ The liquid (fraction E) extracted from the bottom of the column was continuously extracted by a pump. ＢThe EMC was 0.000003 kmol / h and the DEC was 0.26 kmol / h. Furthermore, a liquid (fraction E) was obtained at a rate of 0.13 kmol / h from the top of the distillation column. Ｌ The liquid (fraction E) extracted from the top of the column was continuously extracted by a pump. Ｌ ) EMC 0.13 kmol / h, DEC 0.000003 kmol / h.

[0168] Example 7 A method for producing ethyl methyl carbonate was carried out using the apparatus shown in Figure 5. DMC was fed at 475.2 kg / h (5.28 kmol / h), EtOH at 210.7 kg / h (4.58 kmol / h), and a 3.2 mass% (1.9 mol%) methanol solution of sodium methoxide at a flow rate of 4.3 kg / h (0.13 kmol / h) in a 1.5 m ３ The resulting mixture was fed to a stirred tank reactor, reacted at 50°C and 103 kPaG, and withdrawn from the stirred tank reactor at a rate of 690 kg / h (9.99 kmol / h) to obtain a reaction composition containing EMC. The reaction composition was filtered, then fed to a stirred tank holding 20 kg of solid adsorbent, stirred for 1 hour, filtered, and then fed to distillation column A, where it was distilled as described below.

[0169] EMC was purified in a carbon steel distillation column having 60 perforated trays as follows. The distillation column had a separation capacity of 39 theoretical plates.

[0170] MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.93 kmol / h, EMC 1.98 kmol / h, and DEC 0.37 kmol / h were supplied as a liquid at 50 ° C. on the 46th tray from the bottom of the distillation column. The DMC concentration in the feed liquid was 29.3 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.76. Distillation column A was operated continuously at a column top pressure of 0.0 kPaG, a column bottom pressure of 3.1 kPaG, a column bottom temperature of 109.2 ° C., and a reflux ratio of 1.7.

[0171] A liquid was continuously extracted from the bottom of distillation column A at a rate of 2.36 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction A) ＢThe distillation column A was continuously pumped out at a rate of 7.63 kmol / h from the top of the column. ... Ｌ ) was MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.92 kmol / h, EMC 0.001 kmol / h.

[0172] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was fed to distillation column B and distilled as described below.

[0173] Distillation column B was made of SUS304 and had 27 m of structured packing MellaPak752Y, and EMC was purified as follows: The separation capacity of the distillation column was 48 theoretical plates.

[0174] The liquid extracted from the bottom of distillation column A (fraction A) Ｂ ) was supplied as a liquid at 107°C to a position 13.0 m from the bottom of the packing of distillation column B. Distillation column B was operated at a column top pressure of -40.0 kPaG, a column bottom pressure of -37.9 kPaG, a column bottom temperature of 93.7°C, and a reflux ratio of 1,100.

[0175] A liquid was continuously extracted from the bottom of distillation column B at a rate of 2.35 kmol / h using a pump. The liquid extracted from the bottom of the column (fraction B) Ｂ The distillation column B had a DMC content of 0.00007 kmol / h, EMC content of 1.98 kmol / h, and DEC content of 0.37 kmol / h. The DMC content in the bottom liquid was 25 ppm by mass, achieving a DMC content of 50 ppm by mass or less. Furthermore, a liquid was continuously extracted from the top of the distillation column B at a rate of 0.01 kmol / h using a pump. The liquid extracted from the top of the column (fraction B Ｌ ) was DMC 0.01 kmol / h, EMC 0.0016 kmol / h.

[0176] The liquid extracted from the bottom of distillation column B (fraction B Ｂ ) was fed to distillation column D and distilled as described below.

[0177] Distillation column D was made of SUS304 and had 47 m of structured packing MellaPak752Y, and EMC was purified as follows. The separation capacity of the distillation column was 72 theoretical plates.

[0178] A gaseous fraction was continuously extracted at a rate of 1.92 kmol / h from the portion 26 m from the bottom of the packing of distillation column D, condensed in a condenser, and then continuously extracted as a side cut by a pump. The liquid extracted from the side cut (fraction D Ｓ The distillation column D had a DMC of 0.00002 kmol / h, an EMC of 1.92 kmol / h, and a DEC of 0.00008 kmol / h, achieving EMC purification with a purity of 99.99% by mass or more. Ｂ The liquid (fraction D) extracted from the bottom of the column was continuously extracted by a pump. Ｂ The EMC was 0.06 kmol / h and the DEC was 0.37 kmol / h. Furthermore, a liquid (fraction D) was obtained at a rate of 0.0011 kmol / h from the top of distillation column D. Ｌ The liquid (fraction D) extracted from the top of the column was continuously extracted by a pump. Ｌ ) was DMC 0.00005 kmol / h, EMC 0.0010 kmol / h.

[0179] Comparative Example 1 EMC was purified in a distillation column made of carbon steel and having 60 perforated trays as follows: The separation capacity of the distillation column was 39 theoretical plates.

[0180] MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, EMC 1.98 kmol / h, and DEC 0.37 kmol / h were supplied as a liquid at 50 ° C. onto the 46th tray from the bottom of the distillation column. The liquid was supplied as a liquid at 50 ° C. onto the 46th tray from the bottom of the distillation column. The DMC concentration in the feed liquid was 0 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0. The distillation column was continuously operated at a column top pressure of 0.0 kPaG, a column bottom pressure of 7.1 kPaG, a column bottom temperature of 100.2 ° C., and a reflux ratio of 10.0.

[0181] A liquid of 2.59 kmol / h was continuously withdrawn from the bottom of the distillation column using a pump. The liquid withdrawn from the bottom of the column was MeOH 0.00000 mol / h, EtOH 0.25329 kmol / h, EMC 1.96 kmol / h, and DEC 0.37 kmol / h. The total amount of ethanol and methanol relative to the mass of EMC in the bottom liquid was 57,042 ppm by mass, and a concentration of 20 ppm by mass or less could not be achieved. Furthermore, a liquid of 4.47 kmol / h was continuously withdrawn from the top of the distillation column using a pump. The liquid withdrawn from the top of the column was MeOH 2.85 kmol / h, EtOH 1.61 kmol / h, and EMC 0.016 km.

[0182] Comparative Example 2 EMC was purified in a distillation column made of SUS304 and having 19 m of structured packing MellaPak752Y as follows: The separation capacity of the distillation column was 47 theoretical plates.

[0183] MeOH 3.33 kmol / h, EtOH 1.74 kmol / h, EMC 2.08 kmol / h, and DEC 0.26 kmol / h were supplied as liquids at 50°C to a section 12.7 m from the bottom of the packing of the distillation column. The DMC concentration in the supplied liquid was 0.00 kmol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.00. The distillation column was operated continuously at a column top pressure of 2.5 kPaG, a column bottom pressure of 5.1 kPaG, a column bottom temperature of 91.1°C, and a reflux ratio of 1.0.

[0184] A liquid of 2.55 kmol / h was continuously withdrawn from the bottom of the distillation column using a pump. The liquid withdrawn from the bottom of the column was MeOH 0.00000 kmol / h, EtOH 0.40097 kmol / h, EMC 1.89 kmol / h, and DEC 0.26 kmol / h. The total amount of ethanol and methanol relative to the mass of EMC in the bottom liquid was 93,758 ppm by mass, and a concentration of 20 ppm by mass or less could not be achieved. Furthermore, a liquid of 4.85 kmol / h was continuously withdrawn from the top of the distillation column using a pump. The liquid withdrawn from the top of the column was MeOH 3.33 kmol / h, EtOH 1.34 kmol / h, and EMC 0.185 kmol / h.

[0185] Comparative Example 3 EMC was purified in a distillation column made of SUS304 and having 20 perforated trays as follows: The separation capacity of the distillation column was 13 theoretical plates.

[0186] MeOH 2.85 kmol / h, EtOH 1.86 kmol / h, DMC 2.93 kmol / h, EMC 1.98 kmol / h, and DEC 0.37 kmol / h were supplied as a liquid at 50 ° C. onto the 46th tray from the bottom of the distillation column. The DMC concentration in the feed was 29.3 mol%, and the molar ratio of DMC to the total of EtOH and EMC was 0.76. The distillation column was operated continuously at a column top pressure of 0.0 kPaG, a column bottom pressure of 1.0 kPaG, a column bottom temperature of 105.7 ° C., and a reflux ratio of 1.7.

[0187] A liquid of 5.48 kmol / h was continuously withdrawn from the bottom of the distillation column using a pump. The liquid withdrawn from the bottom of the column was MeOH 0.03 kmol / h, EtOH 0.990194 kmol / h, EMC 2.13 kmol / h, and DEC 0.37 kmol / h. The total amount of ethanol and methanol relative to the mass of EMC in the bottom liquid was 228,767 ppm by mass, and a concentration of 20 ppm by mass or less could not be achieved. Furthermore, a liquid of 4.51 kmol / h was continuously withdrawn from the top of the distillation column using a pump. The liquid withdrawn from the top of the column was MeOH 2.82 kmol / h, EtOH 0.87 kmol / h, DMC 0.80, and EMC 0.023 kmol / h.

[0188] The above results are summarized in Tables 1 to 3.

[0189]

[0190]

[0191]

[0192]

[0193]

[0194]

[0195]

[0196]

[0197]

[0198]

[0199]

[0200] From the above examination of the examples and comparative examples, it can be seen that the method for producing ethyl methyl carbonate according to this embodiment reduces the amount of heat required in the distillation process for producing ethyl methyl carbonate, and makes it possible to produce ethyl methyl carbonate with low ethanol and methanol contents with high efficiency.

[0201] A, B, C, D, E, F Distillation column r Reboiler R Reactor 11 Reaction vessel 12 Raw material supply section 13 Stirring device 14 Withdrawal section

Claims

1. A method for producing ethyl methyl carbonate, comprising: distillation stage A, including feeding the feed mixture containing dimethyl carbonate, ethyl methyl carbonate and ethanol into distillation column A and extracting fraction A B from the bottom of the distillation column A, where the initial mixture contains dimethyl carbonate in an amount of 25 mol.% or more of the total amount of the initial mixture and ethyl methyl carbonate in an amount of 12 mol.% or more of the total amount of the initial mixture, the initial mixture has a molar ratio of dimethyl carbonate / (ethanol+ethyl methyl carbonate) from 0.1 to 2.0, and the proportion of ethanol relative to ethyl methyl carbonate in fraction A B is 20 ppm by weight or less, and the proportion of methanol relative to ethyl methyl carbonate in fraction A B is 20 ppm by weight or less.

2. A method for producing ethyl methyl carbonate according to paragraph 1, further comprising: (1) distillation stage B, including the feeding of fraction AB into distillation column B, and extracting fraction B B , from which a low-boiling substance with a boiling point below the boiling point of ethyl methyl carbonate is removed from the bottom of distillation column B, and distillation stage C, including the feeding of fraction B B into the distillation column C, and extracting the C fraction L from the top of the distillation column C, where is the purity of ethyl methyl carbonate in fraction C L is 99.99% by weight or more, or (2) distillation stage D, including the feeding of fraction A B into the distillation column D, and extracting fraction D B from the bottom of the distillation column D, fraction D L from the top of the column and fraction D S from the intermediate part of the distillation column D, where is the purity of ethyl methyl carbonate in fraction D S is 99.99% by weight or more, or (3) distillation stage B, including the feeding of fraction A B into distillation column B, and extracting fraction B B , from which a low-boiling substance with a boiling point below the boiling point of ethyl methyl carbonate is removed from the bottom of distillation column B, and distillation stage D, including the feeding of fraction B B into the distillation column D, and extracting fraction D B from the bottom of the distillation column D, fraction D L from the top of the column and fraction D S from the intermediate part of the distillation column D, where is the purity of ethyl methyl carbonate in fraction D S constitutes 99.99% by weight or more.

3. The method for producing ethyl methyl carbonate according to claim 1, wherein the pressure at the top of the distillation column A is from 0 kPa (eq) to 50 kPa (eq).

4. The method for producing ethyl methyl carbonate according to claim 1, wherein the method of feeding at least part of the dimethyl carbonate as feedstock to the distillation column A is a single addition of liquid using a pump.

5. The method for producing ethyl methyl carbonate according to claim 1, wherein the initial mixture comes from the intermediate part of the distillation column A.

6. The method for producing ethyl methyl carbonate according to claim 1, wherein the initial mixture contains ethanol in an amount of 0.5 mol.% or more of the total amount of the initial mixture.

7. The method for producing ethyl methyl carbonate according to claim 1, wherein the distillation column A includes a plate and / or a filler as an internal element.

8. A method for producing ethyl methyl carbonate according to any one of paragraphs 1-7, further comprising, before distillation stage A: a reaction step in which dimethyl carbonate and ethanol are subjected to a transesterification reaction in a reaction device to obtain a reaction composition, wherein the reaction composition must be fed into the distillation column A as at least part of the initial mixture.

9. The method for producing ethyl methyl carbonate according to claim 2, further comprising a step of distilling fraction C B or fraction D B , withdrawn from the bottom of the distillation column C or the distillation column D, to obtain diethyl carbonate with a purity of 99.99% by mass or more.

10. A method for producing ethyl methyl carbonate according to any one of paragraphs 1-7, further comprising: before the distillation step A, a reaction step in which dimethyl carbonate and ethanol are subjected to a transesterification reaction in a reaction device to obtain a reaction composition, distillation stage B, including the feeding of fraction A B into distillation column B and extracting fraction B B, from which a low-boiling substance with a boiling point below the boiling point of ethyl methyl carbonate is removed from the bottom of distillation column B, and distillation stage C, including the feeding of fraction B B into the distillation column C and recovery of fraction C L from the top of the distillation column C, wherein the reaction composition is fed into the distillation column A as at least part of the initial mixture, and the purity of ethyl methyl carbonate in fraction C L constitutes 99.99% by weight or more.