Bio-derived ethylene carbonate and its manufacturing method

Abstract

To provide an ethylene carbonate having a reduced environmental load, and a method for producing the same.SOLUTION: Disclosed is a method for producing a bio-based ethylene carbonate having a bio basicity of 95-100% as measured in accordance with ASTM D6866, the method including an ethylene carbonate production step in which bio-based ethylene oxide is reacted with carbon dioxide, which is a by-product from the production of the bio-based ethylene oxide, to produce the ethylene carbonate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to bio-derived ethylene carbonate and a method for producing the same. [Background technology]

[0002] Ethylene carbonate, also known as 1,3-dioxolan-2-one, has various excellent properties. Ethylene carbonate is an excellent polar organic solvent and organic synthetic intermediate, and is widely used in fields such as plastics, dyes, polymer synthesis, gas purification and separation, the electronics industry, and the organic synthesis industry. It is also used, for example, as an extractant for acrylics, nylons, polyesters, polyvinyl chloride esters, etc.; as a foaming agent for plastic and rubber intermediates; as a soil stabilizer; as a paint remover; as a deodorizer for odor removal; as a selective aromatic extraction solvent; and as a solvent for purifying acidic gases in the synthetic ammonia and petroleum industries. Therefore, large-scale industrial production facilities for ethylene carbonate have been developed. It is a solvent primarily used for purifying acidic gases, such as ammonia feed gas, city gas, and oil field gas, and is a liquid crystal solvent for the electronics industry. It is also a raw material for organic products such as laxatives, vinylene carbonate, halogenated vinyl carbonates, dimethyl carbonate, and ethylene glycol.

[0003] In particular, high-purity ethylene carbonate is useful as a good solvent for lithium battery electrolytes. In recent years, with the significant increase in the production of lithium batteries, the market demand for high-purity ethylene carbonate has also increased significantly. A commonly known method for producing ethylene carbonate is to produce ethylene oxide from ethylene and then react the ethylene oxide with carbon dioxide (Patent Documents 1, 2, and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 50-014632 [Patent Document 2] Japanese Patent Application Publication No. 54-987651 [Patent Document 3] Japanese Patent Publication No. 57-106631 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the raw materials ethylene or ethylene oxide are primarily derived from fossil fuels such as petroleum, and carbon dioxide is also primarily derived from fossil fuels emitted from petrochemical plants, etc. Producing ethylene carbonate using such raw materials runs counter to the environmental impact reduction goals that have been gaining attention in recent years, such as the SDGs and carbon neutrality.

[0006] Therefore, an object of the present invention is to provide ethylene carbonate that imposes a reduced burden on the environment, and a method for producing the same. [Means for solving the problem]

[0007] As a result of intensive research into solving the above problems, the present inventors have found that bio-derived ethylene carbonate with a high bio content can be produced by reacting bio-derived ethylene oxide with carbon dioxide, which is a by-product of the production of bio-derived ethylene oxide, and have completed the present invention.

[0008] That is, the present invention relates to the following. [1] The method has an ethylene carbonate production step of producing ethylene carbonate by reacting bio-derived ethylene oxide with carbon dioxide by-produced in the production of bio-derived ethylene oxide. A method for producing bio-based ethylene carbonate with a bio-based content of 95-100% as measured in accordance with ASTM D6866. [2] The method further comprises a first distillation separation step and a second distillation separation step subsequent to the ethylene carbonate production step, the first distillation separation step is a step of continuously introducing ethylene carbonate obtained in the ethylene carbonate production step into a low-boiling point separation column A, and continuously withdrawing from the low-boiling point separation column A an overhead component (At) from the column top and a bottom component (Ab) containing ethylene carbonate from the column bottom, The second distillation separation step is a step of continuously introducing the bottom component (Ab) obtained in the first distillation separation step into a purification column B having a side cut outlet, and continuously withdrawing three components from the purification column B: a top component (Bt) from the top of the column, a side cut component (Bs) from the side cut outlet, and a bottom component (Bb) from the bottom of the column; The production method according to [1], wherein the side cut component (Bs) is ethylene carbonate with a purity of 99.97% by mass or more. [3] The production method according to [2], wherein the amount of liquid held at the bottom of the main column of the low boiling separation column A (L) is VA, the amount of liquid held at the bottom of the main column of the purification column B (L) is VB, and the amount of the side cut component (Bs) withdrawn per hour (t) is BsV, satisfies the conditions of the following formulas (1) and (2). 10≦VA / BsV≦1000 (1) 10≦VB / BsV≦1000 (2) [4] The production method according to [2] or [3], wherein the conditions of the following formulas (3) and (4) are satisfied, where Da is the inner diameter (cm) of the column pot of the low boiling separation column A, Db is the inner diameter (cm) of the column pot of the purification column B, and BsV is the amount (t) of the side cut component (Bs) withdrawn per hour: 10≦Da / BsV≦50 (3) 10≦Db / BsV≦50 (4) [5] A manufacturing method according to any one of [2] to [4], wherein the conditions of the following formulas (5) and (6) are satisfied, where DA is the inner diameter (cm) of the column body of the low boiling separation column A, Da is the inner diameter (cm) of the column pot of the low boiling separation column A, DB is the inner diameter (cm) of the column body of the purification column B, and Db is the inner diameter (cm) of the column pot of the purification column B. 2≦DA / Da≦10 (5) 2≦DB / Db≦10 (6) [6] The production method according to any one of [2] to [5], wherein the reboiler type of the low boiling point separation column A and / or the purification column B is a forced circulation type, a cross pipe falling film type, or a thin film evaporation type. [7] The low boiling point separation column A and / or the purification column B have packing, and the packing is structured packing, The manufacturing method according to any one of [2] to [6], wherein the structured packing is any one of Melapak, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, Glitchgrid, and gauze packing. [8] Bio-based ethylene carbonate with a bio-based content of 95-100% as measured in accordance with ASTM D6866. [9] [8] The bio-derived ethylene carbonate according to [8], having a purity of 99.97% by mass or more. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide ethylene carbonate with reduced environmental impact and a method for producing the same. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of an example of a process flow of the method for producing electronic-grade bioethylene carbonate according to this embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of a process flow of the method for producing bioethylene carbonate according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] [Method for producing bio-based ethylene carbonate] The method for producing bio-based ethylene carbonate of this embodiment includes an ethylene carbonate production step of producing ethylene carbonate by reacting bio-based ethylene oxide with carbon dioxide, a by-product of the production of bio-based ethylene oxide. The bio-based ethylene carbonate produced by this production method of this embodiment has a bio-based content of 95 to 100% (both inclusive, and the same applies unless otherwise specified in this specification) as measured in accordance with ASTM D6866.

[0013] Ethylene oxide is a compound represented by the following formula (1). In the above-mentioned ethylene carbonate production process, bio-derived ethylene oxide (hereinafter also simply referred to as "bioethylene oxide") is used as a raw material. Herein, bioethylene oxide means ethylene oxide having a bio-based content of 95 to 100% as measured in accordance with ASTM D6866. The bio-based content of bioethylene oxide is preferably 97% or more. [ka]

[0014] The bioethylene oxide may be commercially available ethylene oxide or may be produced by a conventionally known method, as long as it has a biobased content of 95 to 100% as measured in accordance with ASTM D 6866. For example, bioethylene oxide may be produced by an ethylene oxide production process in which bio-derived ethylene is oxidized with air to produce bioethylene oxide. Such bio-derived ethylene (hereinafter simply referred to as "bioethylene") can be produced on an industrial scale by known production methods. For example, technologies for producing bioethylene by dehydrating bioethanol produced from biomass have been commercialized by Braskem and ETH Bioenergia in Brazil.

[0015] The ethylene oxide production process is, for example, a process in which bioethylene is oxidized with air to obtain bioethylene oxide. The ethylene oxide production process is, for example, a process in which the bioethylene is reacted with oxygen in the presence of a silver-supported alumina catalyst at 1 to 3 MPa and 200 to 300°C. In such a process, carbon dioxide is by-produced.

[0016] The carbon dioxide used in the ethylene carbonate production process is obtained by capturing and purifying carbon dioxide produced as a by-product in the production of bio-derived ethylene oxide. Such carbon dioxide may be carbon dioxide produced as a by-product in the above-mentioned ethylene oxide production process.

[0017] The ethylene carbonate production process is not particularly limited as long as it is a process for producing ethylene carbonate from the above-mentioned bioethylene oxide and carbon dioxide. The ethylene carbonate production process is preferably carried out by the method for producing cyclic alkyl carbonate described in the following International Publication No. 2004 / 108696.

[0018] Specifically, this is a method for producing ethylene carbonate by reacting ethylene oxide with carbon dioxide in a reactor in the presence of a catalyst, wherein the reactor is connected via piping to a process-side flow path of a heat exchanger to form a circulation circuit, and the heat exchanger has a heat exchange-side flow path for passing a heat exchange medium whose temperature is adjusted to be within a predetermined temperature range, and a process-side flow path for passing a process liquid that undergoes heat exchange in connection with the production of ethylene carbonate, and the production method is characterized by passing a heat exchange medium having a temperature of 140 to 200°C through the heat exchange-side flow path of the heat exchanger during or after the reaction, while passing the process liquid through the circulation circuit including the reactor and the process-side flow path of the heat exchanger, thereby maintaining the internal temperature of the process-side flow path at 135 to 200°C.

[0019] An example of a method for producing bioethylene carbonate according to this embodiment will be described below. For ease of explanation, the following describes an embodiment in which bioethylene carbonate is produced from an ethylene oxide production step and an ethylene carbonate production step, but the scope of the present invention is not limited thereto. That is, the method for producing bioethylene carbonate according to this embodiment does not necessarily have to include an ethylene oxide production step, and the ethylene carbonate production step may be carried out using commercially available bioethylene oxide. Furthermore, the carbon dioxide used in the ethylene carbonate production step is not particularly limited as long as it is carbon dioxide by-produced in the production of bioethylene oxide, and such carbon dioxide may be procured and used. The carbon dioxide is not limited to carbon dioxide by-produced in the ethylene oxide production step described above, and may also be carbon dioxide by-produced in a method for producing bioethylene oxide other than the ethylene oxide production step described above. The carbon dioxide is preferably carbon dioxide by-produced in the ethylene oxide production step described above.

[0020] (Ethylene oxide manufacturing process) The ethylene oxide production process is a process for obtaining bioethylene oxide from bioethylene. The ethylene oxide production process is preferably a process for producing bioethylene oxide and by-producing carbon dioxide. The bioethylene used as a raw material in the ethylene oxide production process is not particularly limited as long as it is ethylene obtained from biomass. For example, bioethylene may be ethylene obtained by dehydrating bioethanol. To confirm whether the ethylene used as a raw material is bio-derived, the biobased content measured in accordance with ASTM D6866 may be used. The biobased content of the ethylene used as a raw material is, for example, 97% or more, preferably 100%. The biobased content of the bioethylene may be 95 to 100%.

[0021] The ethylene oxide production process is, for example, a process in which bioethylene is oxidized with air in the presence of a suitable catalyst. The catalyst is not particularly limited, but is, for example, a solid catalyst supported on silver, preferably an alumina catalyst supported on silver. The pressure in the reaction system in the ethylene oxide production process is, for example, 0.1 to 10 MPa, preferably 0.5 to 5.0 MPa, and more preferably 1.0 to 3.0 MPa. The reaction temperature in the ethylene oxide production process is, for example, 100 to 500°C, preferably 150 to 400°C, and more preferably 200 to 300°C.

[0022] (Ethylene carbonate manufacturing process) The ethylene carbonate production process may be a process in which the bioethylene oxide obtained in the ethylene oxide production process is further reacted with carbon dioxide to produce ethylene carbonate. In the bioethylene carbonate production process, the bioethylene oxide is preferably reacted with carbon dioxide in the presence of a catalyst in a reactor to obtain a reaction mixture in the reactor. The reaction mixture contains ethylene carbonate represented by the following formula (2): [ka]

[0023] In the bioethylene carbonate production process, the reaction for obtaining ethylene carbonate from bioethylene oxide and carbon dioxide is represented by the following formula (3). [ka]

[0024] The bio-based ethylene carbonate obtained in the ethylene carbonate production process has a bio-based content of 95 to 100% as measured in accordance with ASTM D6866. Within the above range, the bio-based content of bioethylene carbonate is preferably 96% or more, more preferably 97% or more, even more preferably 98% or more, even more preferably 99% or more, and particularly preferably 100%. In order to increase the bio-based content of bioethylene carbonate, for example, the bio-based content of bioethylene oxide or bioethylene used as a raw material may be increased. Alternatively, the bio-based content of bioethylene carbonate may be increased by using carbon dioxide by-produced in a method for producing bioethylene oxide with a high bio-based content. The carbon dioxide used in the ethylene carbonate production process is preferably carbon dioxide produced as a by-product in a method for producing bioethylene oxide having a bio-based content of 95 to 100% (preferably 97% or more, and more preferably 100%).

[0025] In the bioethylene carbonate production process, the catalyst used in the reaction of bioethylene oxide with carbon dioxide is not particularly limited, as long as it is a catalyst commonly used to carry out the reaction of formula (3) above. Specifically, organic catalyst metals such as tetraethylammonium bromide, halides of five-membered rings or six-membered ring hydrocarbons, rhodanium ammonium, or their thermal decomposition products; inorganic catalysts such as alkali metal bromides or iodides; and catalysts obtained by adding a small amount of alcohol or water to these catalysts are used. Among these, inorganic catalysts are preferred from the viewpoint of easy catalyst recovery. The amount of catalyst used is not particularly limited, but is preferably 0.1 to 3 mass % of the reaction system, and more preferably 0.1 to 2 mass %.

[0026] In the bioethylene carbonate production process, the reaction temperature between bioethylene oxide and carbon dioxide is preferably 100 to 200°C, more preferably 150 to 190°C. The reaction pressure is preferably 2 to 15 MPa, more preferably 4 to 12 MPa. The reaction time varies depending on the composition ratio of the raw materials, bioethylene oxide and carbon dioxide, the type of bioethylene oxide, the type and concentration of the catalyst used, the reaction temperature, etc. For example, if the reaction time is defined as the average residence time calculated from the amount of retained liquid in the complete mixing reactor and the total amount of liquid fed, it is usually 0.5 to 10 hours, preferably 1 to 5 hours.

[0027] In carrying out the bioethylene carbonate production process, the ratio of the amounts of raw materials, bioethylene oxide and carbon dioxide, expressed as the molar ratio of carbon dioxide to bioethylene oxide, is usually 1 to 5, preferably 1 to 2. Usually, when excess carbon dioxide gas is released from the reactor, the amount of unreacted bioethylene oxide that accompanies it also increases. Therefore, when adjusting the ratio of the amounts of bioethylene oxide and carbon dioxide, it is preferable to adjust the amount of carbon dioxide supplied so that the reactor pressure is constant, rather than releasing the excess carbon dioxide gas from the reactor.

[0028] The reactor for carrying out the above reaction in the bioethylene carbonate production process is preferably connected to the process side flow path of the heat exchanger via piping to form a circulation circuit.

[0029] As the reaction method for the bioethylene carbonate production process, a commonly used reaction method such as a complete mixing reactor, a multistage reaction method using complete mixing reactors in series, a plug flow reactor, or a method combining a complete mixing reactor and a plug flow reactor can be used.

[0030] When bioethylene carbonate is produced using a complete mixing reactor, a method of circulating the reaction mixture at a high flow rate using a pump is preferred so that carbon dioxide can be easily dissolved in the reaction mixture. The number of circulations per unit time is usually 10 to 50 times / hour, preferably 20 to 40 times / hour. When a heat exchanger is installed in the piping through which the reaction mixture is circulated by pumping to remove the heat of reaction, circulating at a high flow rate is preferred because it increases the cooling capacity of the heat exchanger.

[0031] A heat exchanger used in a bioethylene carbonate production process preferably has a heat exchange side flow path for passing a heat exchange medium whose temperature has been adjusted to within a predetermined temperature range, and a process side flow path for passing a process liquid that undergoes heat exchange in connection with the production of bioethylene carbonate. The process liquid is a liquid that is treated (i.e., whose temperature is adjusted) by the heat exchanger, and the heat exchange medium is a medium for adjusting the temperature of the process liquid. The heat exchange side flow path of the heat exchanger is a flow path for passing the heat exchange medium, and the process side flow path is a flow path for passing the process liquid.

[0032] The heat exchanger is preferably one that can flow a heat exchange medium at a temperature of 140 to 200°C through the heat exchange side flow path of the heat exchanger and maintain the internal temperature of the process side flow path at 135 to 200°C. For example, a coiled-tube heat exchanger, a double-tube heat exchanger, or a general multi-tube heat exchanger, which are installed inside the reactor, can be used alone or in combination. The heat exchanger is preferably a multi-tube heat exchanger, which has a large heat transfer area and can be made smaller.

[0033] When a multi-tubular heat exchanger is used, the process liquid and heat exchange medium may be passed through either the tube side or the shell side of the multi-tubular heat exchanger as the heat exchange side flow path or the process side flow path. The liquids passed through the tube side and the shell side of the heat exchanger can be selected appropriately depending on whether a small heat exchanger is used and the overall heat transfer coefficient (U) is to be increased, or whether a fluid that easily attracts fouling substances should be passed through the tube side to facilitate cleaning.

[0034] The heat exchanger is preferably a device that functions as both a preheater and a cooler, and can be used as a preheater to heat the reaction solution to the reaction initiation temperature at start-up, and as a cooler to remove the heat of reaction during steady-state operation.

[0035] The material of the process side flow path of the heat exchanger is not particularly limited as long as it is corrosion-resistant to the process liquid. Since iron rust causes the formation of bioethylene oxide polymers due to its catalytic action, stainless steel is preferably used.

[0036] The heat exchange medium used in the bioethylene carbonate production process is preferably one that can maintain its temperature at 140 to 200°C, preferably 140 to 180°C, and examples thereof include media commonly used as heat exchange media, such as water, steam, and heat transfer oil. Heat transfer oil, which is thermally stable and has a low vapor pressure, is preferred as the heat exchange medium, from the viewpoint of enabling a lower design pressure for the heat exchanger. Furthermore, since the temperature of heat transfer oil is easy to adjust, when it is used as the heat exchange medium, the reaction temperature can be adjusted by increasing or decreasing the supply rate of the heat exchange medium, which tends to facilitate the operation of the bioethylene carbonate production apparatus.

[0037] (separation process) The method for producing bio-based ethylene carbonate of this embodiment may further include a first distillation separation step and a second distillation separation step subsequent to the ethylene carbonate production step, in addition to the ethylene carbonate production step, or in addition to the ethylene oxide production step and the ethylene carbonate production step. Such an embodiment tends to facilitate the production of electronic-grade bio-ethylene carbonate.

[0038] In this specification, electronic-grade bioethylene carbonate refers to bioethylene carbonate having a purity of 99.97% by mass or more, a content of each of the three components, alkylene oxide, alkylene glycol, and dialkylene glycol, of 50 ppm by mass or less, a water content of 50 ppm by mass or less, and a content of each of the nine metal components, sodium, potassium, copper, iron, lead, zinc, chromium, nickel, and calcium, of 1 μg / mL or less.

[0039] The method for producing bio-based ethylene carbonate of this embodiment may include only the first distillation separation step, or may include both the first distillation separation step and the second distillation separation step, or may include a separation step other than the first distillation separation step and the second distillation separation step. Hereinafter, the production method including the first distillation separation step and the second distillation separation step will be referred to as the "production method for electronic-grade bioethylene carbonate of the present embodiment" to distinguish it from the production method for bio-based ethylene carbonate of the present embodiment that does not include the first distillation separation step and the second distillation separation step. However, the "production method for electronic-grade bioethylene carbonate of the present embodiment" does not necessarily have to produce electronic-grade bioethylene carbonate as defined above. In other words, the production method for electronic-grade bioethylene carbonate of the present embodiment may produce electronic-grade bioethylene carbonate, or may produce bioethylene carbonate that does not fall under the definition of electronic-grade bioethylene carbonate. Furthermore, the production method for electronic-grade bioethylene carbonate of the present embodiment may be the same as the above-described production method for bio-based ethylene carbonate of the present embodiment, except for including the first distillation separation step and the second distillation separation step.

[0040] The first distillation separation step is a step in which bioethylene carbonate obtained in the ethylene carbonate production step is continuously introduced into a low boiling point separation column A, and in the low boiling point separation column A, a top component (At) is continuously extracted from the top of the column and a bottom component (Ab) containing ethylene carbonate is continuously extracted from the bottom of the column. The second distillation separation step is a step in which the bottom component (Ab) obtained in the first distillation separation step is continuously introduced into an ethylene carbonate purification column B (hereinafter also simply referred to as "purification column B") having a side outlet (side cut outlet), and three components are continuously withdrawn from the purification column B: a top component (Bt) from the column, a side cut component (Bs) from the side outlet, and a bottom component (Bb) from the column bottom. Here, the side cut component (Bs) is ethylene carbonate with a purity of 99.97% by mass or more, and is preferably electronic-grade bioethylene carbonate.

[0041] The method for producing electronic-grade bioethylene carbonate according to this embodiment tends to enable efficient industrial-scale production of electronic-grade bioethylene carbonate by purifying the bioethylene carbonate through a specific distillation separation process. Specifically, bioethylene carbonate is continuously introduced into low-boiling separation column A, and a top component (At) and a bottom component (Ab) containing bioethylene carbonate are continuously withdrawn from the top and bottom of low-boiling separation column A, respectively, without side-cut withdrawal. This method allows low-boiling separation column A (first column) to be specialized for removing low-boiling components, thereby shortening the column height and reducing capital investment. The bottom component (Ab) is then continuously introduced into a purification column B having a side outlet. In the purification column B, three components are continuously withdrawn: a low-boiling component (top component (Bt)) from the column, bioethylene carbonate (side cut component (Bs)) from the side outlet, and a high-boiling component (bottom component (Bb)) from the column bottom. This allows the removal of trace amounts of both the low-boiling and high-boiling components, thereby producing bioethylene carbonate of electronic grade specifications. Furthermore, since most of the low-boiling components have been removed in the low-boiling separation column A (first column), purification column B (second column) has ample column load capacity, allowing for reduced energy consumption for separation. Furthermore, since the column load is not increased in purification column B, the column pressure drop can be reduced and the column bottom temperature can be lowered. This reduces the amount of low-boiling and high-boiling by-products produced by the decomposition and polymerization of bioethylene carbonate, resulting in reduced waste.

[0042] In this specification, the term "industrial scale" refers to a scale in which ethylene carbonate is produced at a rate of 1 t (ton) / hour or more, preferably 2 t (ton) / hour or more, more preferably 3 t (ton) / hour or more, and even more preferably 4 t (ton) / hour or more. The upper limit of the industrial scale is not particularly limited, but is, for example, 15 t (ton) / hour or less.

[0043] The purity of the bioethylene carbonate continuously introduced into low-boiling point separation column A is not particularly limited, and may be, for example, 99.5% by mass or less. Conventionally, in order to obtain bioethylene carbonate of electronic grade specifications, the purity of the bioethylene carbonate continuously introduced into low-boiling point separation column A needs to be 99.7% by mass or more. However, in the method for producing bioethylene carbonate of electronic grade specifications of the present embodiment, even if the purity of the bioethylene carbonate continuously introduced into low-boiling point separation column A is 99.5% by mass or less, sufficient distillation separation is possible because low-boiling point separation column A is specialized for removal of low-boiling point components, and electronic grade bioethylene carbonate can ultimately be obtained.

[0044] Figure 1 is a schematic diagram of an example of a process flow for the production of electronic-grade bioethylene carbonate according to this embodiment. In Figure 1, A is a low-boiling point separation column that continuously distills and separates bioethylene carbonate and low-boiling point components, and B is a purification column that continuously distills and separates the bioethylene carbonate into three components: a top component (Bt), a side cut component (Bs), and a bottom component (Bb). A2 is the top condenser of low-boiling point separation column A, and A5 is the reboiler for low-boiling point separation column A. Similarly, B2 is the top condenser of purification column B, and B5 is the reboiler for purification column B.

[0045] In the method for producing electronic-grade bioethylene carbonate of this embodiment, components containing electronic-grade bioethylene carbonate are withdrawn from the bottom of light-boiling separation column A rather than from a side outlet, thereby making it possible to shorten the column height and reduce capital investment. Furthermore, by specializing light-boiling separation column A solely in the removal of low-boiling components, a margin in column load is created, energy costs can be reduced, and the yield of the final electronic-grade bioethylene carbonate is improved.

[0046] The material of the low boiling point separation column A is not particularly limited, but examples thereof include carbon steel, stainless steel, and high alloy steel, with stainless steel being particularly preferred.

[0047] Furthermore, the number of theoretical plates in the low boiling point separation column A is preferably 10 to 50, more preferably 15 to 40, and even more preferably 20 to 30. In the low boiling point separation column A, bioethylene carbonate is preferably introduced from the 1st to 40th theoretical plate position from the top, more preferably from the 3rd to 30th plate position from the top, and even more preferably from the 5th to 20th plate position from the top.

[0048] In the low boiling point separation column A, the amount of bioethylene carbonate introduced is preferably 1500 to 15000 kg / hour, more preferably 3000 to 14000 kg / hour, and even more preferably 4000 to 13500 kg / hour.

[0049] In the low boiling point separation column A, a low boiling point component (column top component (At)) is withdrawn from the column top. The withdrawal flow rate of the column top component (At) is preferably 135 to 1500 kg / hour, more preferably 250 to 1450 kg / hour, and even more preferably 300 to 1400 kg / hour.

[0050] A bottoms component (Ab) containing bioethylene carbonate is withdrawn from the bottom of the low boiling point separation column A. The withdrawal flow rate of the bottoms component (Ab) is preferably 1,300 to 14,500 kg / hour, more preferably 3,000 to 14,000 kg / hour, and even more preferably 4,000 to 13,500 kg / hour.

[0051] In the method for producing electronic-grade bioethylene carbonate of this embodiment, the low-boiling separation column A is specialized for removing low-boiling components, so that sufficient separation of low-boiling components is possible even when the purity of the bioethylene carbonate introduced into the column is equivalent to industrial-grade purity, and bioethylene carbonate with a small amount of low-boiling components can be obtained as the column bottom component (Ab).

[0052] Furthermore, the operating conditions for the low boiling separation column A are such that the column top reflux ratio is preferably 1 to 40, more preferably 5 to 30, and even more preferably 10 to 20. In the low boiling separation column A, the column top reflux amount is preferably 200 to 60,000 kg / hour, more preferably 1,250 to 43,500 kg / hour, and even more preferably 3,000 to 28,000 kg / hour. In the low boiling separation column A, the column bottom temperature is preferably 100 to 150°C, more preferably 110 to 140°C, and even more preferably 120 to 130°C. In the method for producing electronic-grade bioethylene carbonate according to this embodiment, the bioethylene carbonate-containing component is withdrawn from the bottom of the low-boiling separation column A rather than from a side outlet. This avoids an increase in column load, thereby reducing column pressure loss and the column bottom temperature. This reduces the amount of low-boiling by-products and high-boiling by-products produced by bioethylene carbonate decomposition and polymerization, resulting in reduced waste. In the low-boiling separation column A, the reboiler steam consumption is preferably 100 to 17,600 kg / h, more preferably 350 to 13,000 kg / h, and even more preferably 800 to 9,000 kg / h. In the low-boiling separation column A, the bioethylene carbonate-containing component is withdrawn from the bottom of the column rather than from a side outlet. This avoids an increase in column load, thereby reducing column pressure loss and the column bottom temperature. This reduces steam consumption.

[0053] The material of the purification column B is not particularly limited, but examples include carbon steel, stainless steel, and high-alloy steel, with stainless steel being particularly preferred. The number of theoretical plates in the purification column B is preferably 5 to 30, more preferably 6 to 20, and even more preferably 7 to 15. In the purification column B, the bottom component (Ab) from the low-boiling separation column A is preferably introduced from the 1st to 25th theoretical plate position from the top, more preferably from the 2nd to 15th theoretical plate position from the top, and even more preferably from the 3rd to 10th theoretical plate position from the top.

[0054] Furthermore, in purification column B, the side outlet is preferably located at the 1st to 25th theoretical plate from the top, more preferably at the 2nd to 15th theoretical plate from the top, and even more preferably at the 3rd to 10th theoretical plate from the top.

[0055] Furthermore, the operating conditions for purification column B are such that the top reflux ratio is preferably 10 to 100, more preferably 50 to 90, and even more preferably 60 to 80. In purification column B, the top reflux rate is preferably 400 to 25,000 kg / hour, more preferably 2,500 to 21,000 kg / hour, and even more preferably 3,600 to 16,000 kg / hour. In purification column B, a low boiling point component (top component (Bt)) is extracted from the top of the column. The extraction rate of the top component (Bt) is preferably 25 to 250 kg / hour, more preferably 50 to 230 kg / hour, and even more preferably 60 to 200 kg / hour. In purification column B, a high boiling point component (bottom component (Bb)) is extracted from the bottom of the column. The withdrawal rate of the column bottom component (Bb) is preferably 15 to 150 kg / hour, more preferably 25 to 140 kg / hour, and even more preferably 30 to 130 kg / hour. In the purification column B, bioethylene carbonate is withdrawn as a side cut component (Bs) from a side outlet. The withdrawal rate of the side cut component (Bs) is preferably 1,300 to 14,000 kg / hour, more preferably 2,500 to 13,000 kg / hour, and even more preferably 3,000 to 12,500 kg / hour.

[0056] As described above, the bioethylene carbonate obtained as the side-cut component (Bs) is preferably a bioethylene carbonate having a purity of 99.97% by mass or more and meeting electronic-grade specifications. That is, the bioethylene carbonate obtained as the side-cut component (Bs) preferably has a purity of 99.97% by mass or more, and in addition, the contents of each of the three components, alkylene oxide, alkylene glycol, and dialkylene glycol, are 50 ppm by mass or less, the water content is 50 ppm by mass or less, and the contents of each of the nine metal components, sodium, potassium, copper, iron, lead, zinc, chromium, nickel, and calcium, are 1 μg / mL or less.

[0057] In this embodiment, the purity of bioethylene carbonate, and the contents of alkylene oxide, alkylene glycol, dialkylene glycol, and metal components can be measured by the methods described in the Examples below.

[0058] In purification column B, the temperature at the column bottom is preferably 100 to 150°C, more preferably 110 to 140°C, and even more preferably 120 to 130°C. In the method for producing electronic-grade bioethylene carbonate according to this embodiment, low-boiling components are sufficiently removed in low-boiling separation column A, so that the column load and column bottom temperature in purification column B can be reduced. This reduces the amount of low-boiling by-products and high-boiling by-products produced by decomposition and polymerization of bioethylene carbonate, and as a result, the amount of waste can be suppressed. In purification column B, the steam consumption rate in the reboiler is preferably 100 to 7,300 kg / hour, more preferably 600 to 6,100 kg / hour, and even more preferably 900 to 4,700 kg / hour. In the method for producing electronic-grade bioethylene carbonate of this embodiment, low-boiling point components are sufficiently removed in the low-boiling separation column A, so that the column load in the purification column B can be reduced and the column bottom temperature can be lowered, thereby reducing the amount of steam used.

[0059] As described above, in the second distillation separation step, by continuously introducing the bottom component (Ab) into purification column B and withdrawing bioethylene carbonate from the side outlet, it is possible to remove both the small amounts of low-boiling and high-boiling components remaining, and this tends to produce electronic-grade bioethylene carbonate. Furthermore, since most of the low-boiling components have been removed in low-boiling separation column A (first column), purification column B (second column) has ample column load capacity, allowing for reduced energy consumption for separation. Furthermore, since purification column B does not increase its column load, the pressure drop in the column can be reduced and the column bottom temperature can be lowered. This reduces the amount of low-boiling and high-boiling by-products produced by the decomposition and polymerization of bioethylene carbonate, thereby resulting in reduced waste.

[0060] As described above, the production method of this embodiment makes it possible to stably and efficiently produce bioethylene carbonate of electronic grade specifications on an industrial scale for a long period of time.

[0061] In this embodiment, the separation column has a column body and a column kettle. In this specification, the term "column kettle" refers to the liquid-retaining portion (semispherical portion) at the bottom of the column, and the term "column body" refers to the column portion extending from the column kettle. Furthermore, the term "liquid retention capacity at the column bottom" refers to the amount of liquid that can be retained in the column kettle. In addition, the inner diameter of the tower body of low boiling separation tower A refers to the inner diameter (cm) at the position of the long diameter part over the entire length of the tower, and the inner diameter of the tower pot of low boiling separation tower A refers to the inner diameter (cm) at the position of the small diameter part holding the liquid at the bottom of the tower.

[0062] In the steady state of continuous operation of the method for producing bioethylene carbonate of electronic grade specifications according to this embodiment, when the amount of liquid held at the bottom of the main column of the low boiling point separation column A (L) is defined as VA, the amount of liquid held at the bottom of the main column of the purification column B (L) is defined as VB, and the amount of side cut component (Bs) withdrawn (t / hour) (i.e., the amount withdrawn per hour (t (tons))) is defined as BsV, it is preferable that the conditions of the following formulas (1) and (2) are satisfied. 10≦VA / BsV≦1000 (1) 10≦VB / BsV≦1000 (2)

[0063] When the conditions of the above formulas (1) and (2) are satisfied, it tends to be possible to suppress the production of low-boiling point by-products and high-boiling point by-products due to the decomposition of bioethylene carbonate, polymerization reaction, etc. From the same viewpoint, VA / BsV is more preferably 20 to 500, and even more preferably 30 to 200, and VB / BsV is more preferably 20 to 500, and even more preferably 30 to 200.

[0064] In this embodiment, the steady state of continuous operation is a state in which each flow rate is stable within a predetermined range, and this steady state is usually reached 72 hours or more after the raw materials are charged.

[0065] In the steady state of continuous operation of the method for producing bioethylene carbonate of electronic grade specifications according to this embodiment, when the inner diameter (cm) of the column pot of the low boiling point separation column A is Da, the inner diameter (cm) of the column pot of the purification column B is Db, and the amount (t / hour) of the side cut component (Bs) taken out is BsV, it is preferable that the conditions of the following formulas (3) and (4) are satisfied. 10≦Da / BsV≦50 (3) 10≦Db / BsV≦50 (4)

[0066] When the conditions of the above formulas (3) and (4) are satisfied, it tends to be possible to suppress the production of low-boiling point by-products and high-boiling point by-products due to the decomposition of bioethylene carbonate, polymerization reaction, etc. From the same viewpoint, Da / BsV is more preferably 12 to 40, and even more preferably 15 to 30, and Db / BsV is more preferably 12 to 40, and even more preferably 15 to 30.

[0067] In the method for producing electronic-grade bioethylene carbonate of this embodiment, when the inner diameter (cm) of the column body of low-boiling separation column A is DA, the inner diameter (cm) of the column pot of low-boiling separation column A is Da, the inner diameter (cm) of the column body of purification column B is DB, and the inner diameter (cm) of the column pot of purification column B is Db, it is preferable that the conditions of the following formulas (5) and (6) are satisfied. 2≦DA / Da≦10 (5) 2≦DB / Db≦10 (6)

[0068] When the conditions of the above formulas (5) and (6) are satisfied, it tends to be possible to suppress the production of low-boiling point by-products and high-boiling point by-products due to the decomposition of bioethylene carbonate, polymerization reaction, etc. From the same viewpoint, DA / Da is more preferably 3 to 8, and even more preferably 3 to 7, and DB / Db is more preferably 3 to 8, and even more preferably 3 to 7.

[0069] In this embodiment, the reboiler type of the low boiling point separation column A and / or the purification column B is preferably a forced circulation type, a cross-pipe falling film type, or a thin film evaporation type. Use of such a reboiler improves heat exchange efficiency, reduces the temperature of the tube wall that comes into contact with the process fluid, and suppresses the generation of impurities due to decomposition or polymerization.

[0070] In this embodiment, it is preferable that the low boiling point separation column A and / or the purification column B contain packing. The packing is preferably structured packing. Examples of the structured packing include those made of metal or resin, and are preferably Melapack, Gempack, Technopack, Flexipack, Sulzer packing, Goodroll packing, Glitch grid, or gauze packing. [Example]

[0071] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0072] [Analysis of bioethylene carbonate] [Purity of ethylene carbonate] The purity of the ethylene carbonate obtained in the examples and comparative examples was measured by the gas chromatography method described in Chinese standards HG / T5391.

[0073] [Contents of alkylene oxide, alkylene glycol, and dialkylene glycol] The contents of each of the three components, alkylene oxide, alkylene glycol and dialkylene glycol, in the ethylene carbonate obtained in the examples and comparative examples were measured by the gas chromatography method described in HG / T5391.

[0074] [Moisture content] The water content in the ethylene carbonate obtained in the examples and comparative examples was measured by the coulometric titration method described in HG / T5391.

[0075] [Metal component content] The contents of each of the nine metal components, i.e., sodium, potassium, copper, iron, lead, zinc, chromium, nickel, and calcium, in the ethylene carbonate obtained in the examples and comparative examples were measured by the inductively coupled plasma (ICP) method described in HG / T5391. [Bio-based content] Measurements were made using the method described in ASTM D6866. Note that measurements made using this method are said to have a maximum error of ±3%, and measurements greater than 100% were considered to be 100% biobased. Measurements less than 0% were considered to be 0%.

[0076] [Example 1] Bioethylene carbonate was produced as follows using the same apparatus and production method as in Example 1 of WO 2004 / 108696. Bioethylene carbonate was produced using the production apparatus shown in Figure 2. The bioethylene oxide and carbon dioxide used were obtained from external sources. The carbon dioxide was a by-product of the production of the bioethylene oxide, and the biobased content of the bioethylene oxide was 95 to 100%.

[0077] The reactor 10 has an inner diameter of 1.6 m, a straight body length of 8 m, and a capacity of 20 m 3The reactor is a vertical cylindrical vessel made of stainless steel, with a liquid dispersion nozzle at the top to increase the absorption efficiency of carbon dioxide gas. The vessel is connected to the process flow path of the heat exchanger via piping to form a circulation circuit. Heat exchanger 14 is a one-pass heat exchanger (heat transfer area: 1476.6 m). 2 The reactor had a tube outer diameter of 42.7 mm, a tube length of 6.95 m, and 172 tubes. The tube side served as the process flow path, carrying the process liquid, while the shell side served as the heat exchange side flow path, carrying the heat exchange medium. The heat exchange side flow path (shell side) of heat exchanger 14 was filled with thermal oil (product name: KSK-oil-280) manufactured by Soken Chemical & Engineering Co., Ltd., Japan, as the heat exchange medium. This thermal oil was used as a heating fluid during startup and as a cooling fluid during steady-state operation. Bioethylene oxide, one of the feedstocks, cooled to approximately 5°C was supplied via pipe 7 to bioethylene oxide pump 2, where it was pressurized and supplied via pipe 25 to reactor 10 from pipe 15 at a rate of 2,500 kg / h. For the other feedstock, carbon dioxide, liquefied carbon dioxide was supplied via pipe 5 to carbon dioxide supply pump 1. The pressure was increased there, and the gas was gasified in a hot water bath type carbon dioxide evaporator 4, and the gas was supplied at a temperature of about 90°C through a pipe 6 to the gas phase at the top of a reactor 10, adjusting the pressure to a constant 9.5 MPa. The average carbon dioxide supply rate was 2,700 kg / hour.

[0078] If the pressure in the reactor 10 rose to 10 MPa or more for some reason, the reactor vent gas control valve 23 was opened to discharge the gas phase gas in the reactor 10 via pipes 22 and 24, thereby reducing the pressure in the reactor 10.

[0079] Potassium iodide (KI) was used as the catalyst and was mixed into the bioethylene carbonate solution to give a concentration of 5 wt%. The catalyst solution was prepared by mixing 9 parts recovered catalyst recovered after purifying the bioethylene carbonate product and 1 part fresh catalyst solution, and the mixture was supplied to catalyst feed pump 3 via pipe 8, and then to reactor 10 via pipe 26 and pipe 15. The catalyst feed pump 3 was set to supply the catalyst solution at a rate of 274 kg / hour so that the potassium iodide concentration in the reactor circulating liquid (reaction system) would be 0.23 to 0.26 wt%.

[0080] The reaction mixture was discharged from reactor 10 so that the liquid amount in reactor 10 was constant at 14.5 tons. The discharge amount of the reaction mixture was adjusted with discharge control valve 20, and the reaction mixture was discharged through pipes 19 and 21.

[0081] Ethylene carbonate production was carried out under conditions where the reaction temperature, measured by a thermometer T1 installed at the bottom of the reactor 10, was 176 to 177°C. During the reaction, the reaction mixture was passed through the circulation circuit including the reactor 10 and the process-side passage of the heat exchanger 14, while a heat exchange medium was passed through the heat exchange-side passage of the heat exchanger 14. Specifically, the reaction mixture was withdrawn from the outlet of the reactor 10, pressurized by the reactor circulation pump 9, and sent to the heat exchanger 14 via pipes 11 and 12. The reaction mixture, whose temperature had been adjusted in the heat exchanger 14, was then returned to the inlet of the reactor 10 through pipe 15, thereby circulating within the circulation circuit. The amount of the reaction mixture circulated through the reactor 10 was monitored by the reactor circulation flowmeter 13 and adjusted to a constant value of approximately 400 tons / hour. As a result, the average residence time in the reactor was 2.65 hours, and the circulation frequency was 28 times / hour.

[0082] In the heat exchanger 14, the reactor temperature control valve 16 was automatically controlled to adjust the flow rate of the heat exchange medium so that the temperature of the reaction mixture, measured by thermometer T2 installed at the heat exchanger outlet, was constant at 173°C. The heat exchange medium was supplied to the shell side of the heat exchanger 14 through piping 18. The temperature of the heat exchange medium supplied to the heat exchanger 14 was initially set to 140°C and was raised to 145°C on the 23rd day after the start of operation. The temperature of the heat exchange medium was measured by thermometer t1 installed at the heat exchange medium supply port of the heat exchanger 14, and changes in the flow rate were monitored by flow meter 17 for the heat exchange medium. The production rate of bioethylene carbonate was 4,980 kg / h.

[0083] The reaction mixture discharged through pipe 21 was first supplied to a flash tank (not shown), where unreacted ethylene oxide, unreacted carbon dioxide, and trace amounts of bioethylene carbonate were discharged from the system. The operating conditions of the flash tank were 760 Torr and 130°C. Furthermore, a mixture containing mainly bioethylene carbonate was extracted from the bottom of the flash tank and introduced into a bioethylene carbonate recovery column (not shown), which was a thin-film still controlled at 160°C and 49 Torr. The production amount of bio-ethylene carbonate extracted from the bio-ethylene carbonate recovery tower was 4,930 kg / hour. The extracted bio-ethylene carbonate had a bio-based content of 99% and a purity of 99.5% by mass.

[0084] [Example 2] After the method for producing bioethylene carbonate described in Example 1, the obtained bioethylene carbonate was subjected to the following separation steps (first distillation separation step and second distillation separation step). That is, Example 2 corresponds to the method for producing electronic-grade bioethylene carbonate of the present embodiment described above.

[0085] FIG. 1 is a process flow schematic diagram of the method for producing electronic-grade bioethylene carbonate used in Example 2. In FIG. 1, A is a low-boiling separation column that continuously distills and separates bioethylene carbonate and low-boiling components, and B is a purification column that continuously distills and separates three components: a top component (Bt), a side cut component (Bs), and a bottom component (Bb). A2 is the overhead condenser of low-boiling separation column A, and A5 is the reboiler of low-boiling separation column A. Similarly, B2 is the overhead condenser of purification column B, and B5 is the reboiler of purification column B. The reboiler type of low-boiling separation column A was a forced circulation type, and the reboiler type of purification column B was also a forced circulation type. The packings in low-boiling separation column A and purification column B were gauze packing.

[0086] Bioethylene carbonate having a purity of 99.5% by mass, equivalent to industrial grade, produced in Example 1 was used as the feed liquid continuously introduced into the low-boiling separation column A. In Example 2, the low-boiling separation column A was made of stainless steel and had 25 theoretical plates. Bioethylene carbonate was introduced into the low-boiling separation column A from the 14th theoretical plate from the top. Purification column B was made of stainless steel, had 9 theoretical plates, and had a side outlet. The bottom component (Ab) of the low-boiling separation column A was introduced into purification column B from the 7th theoretical plate from the top. In purification column B, the side outlet was set to the 3rd theoretical plate from the top.

[0087] Bioethylene carbonate was introduced into low-boiling separation column A at a flow rate of 5,330 kg / hour. The withdrawal rate of low-boiling components (top component (At)) from the top of low-boiling separation column A was 500 kg / hour. A bottom component (Ab) containing bioethylene carbonate with a purity of 99.75 mass% was withdrawn from the bottom of low-boiling separation column A at a rate of 4,840 kg / hour and introduced into purification column B. In purification column B, the withdrawal rate of low-boiling components (top component (Bt)) from the top was 90 kg / hour, and the withdrawal rate of high-boiling components (bottom component (Bb)) from the bottom was 50 kg / hour. In addition, in purification column B, bioethylene carbonate was withdrawn as a side cut component (Bs) from a side outlet at a rate of 4,710 kg / hour (BsV = 4.710 t / hour). In purification column B, the bioethylene carbonate withdrawn from the side outlet had a purity of 99.994% by mass, a diethylene glycol (hereinafter also referred to as "DEG") concentration of 15 ppm by mass, an ethylene oxide and ethylene glycol content of 30 ppm by mass or less, a water content of 20 ppm by mass or less, and each of the nine metal components, namely sodium, potassium, copper, iron, lead, zinc, chromium, nickel, and calcium, of 1 μg / mL or less, thereby satisfying the specifications for use as an electrolyte (electronic grade specifications).

[0088] The operation conditions of the low boiling point separation column A were a reflux ratio of 14.8, a column top reflux amount of 7400 kg / hour, and a column bottom temperature of 124° C. The amount of steam used in the reboiler of the low boiling point separation column A was 3200 kg / hour. The operation conditions of the purification column B were a reflux ratio of 70.0, a column top reflux amount of 6,300 kg / hour, and a column bottom temperature of 124° C. The amount of steam used in the reboiler of the purification column B was 2,400 kg / hour.

[0089] Furthermore, in the steady state of continuous operation of bioethylene carbonate purification in Example 2, when the amount of liquid held at the bottoms of the main column of low boiling separation column A (L) is defined as VA, the amount of liquid held at the bottoms of the main column of purification column B (L) is defined as VB, the amount of side cut component (Bs) withdrawn (t / hour) is defined as BsV, the inner diameter (cm) of the column main body of low boiling separation column A is defined as DA, the inner diameter (cm) of the column pot of low boiling separation column A is defined as Da, the inner diameter (cm) of the column main body of purification column B is defined as DB, and the inner diameter (cm) of the column pot of purification column B is defined as Db, VA / BsV was 73, VB / BsV was 73, Da / BsV was 19, Db / BsV was 19, DA / Da was 4.4, and DB / Db was 4.

[0090] In Example 2, bioethylene carbonate was continuously introduced into low-boiling separation column A, and without side-cut withdrawal, low-boiling components (column top component (At)) and a column bottom component (Ab) containing bioethylene carbonate were continuously withdrawn and separated by distillation. This method specialized low-boiling separation column A (first column) for removing low-boiling components, thereby enabling a shorter column height and reduced capital investment. Furthermore, specializing low-boiling separation column A for removing low-boiling components created a margin in column load, enabling sufficient separation to produce bioethylene carbonate of specifications equivalent to industrial grade, with a purity of 99.5% by mass. The column bottom component (Ab) was then continuously introduced into purification column B, which has a side withdrawal port, and bioethylene carbonate was withdrawn from the side withdrawal port. This enabled the removal of traces of low-boiling and high-boiling components, enabling the production of electronic-grade bioethylene carbonate. Furthermore, since most of the low boiling point components were removed in the low boiling point separation tower A (first tower), there was room for the tower load in the purification tower B (second tower), and the energy consumption for separation could be reduced. Furthermore, since the tower load in the purification tower B was not increased, the pressure loss in the tower could be reduced and the tower bottom temperature could be lowered, which reduced the amount of low boiling point by-products and high boiling point by-products produced by decomposition and polymerization reactions, and as a result, the amount of waste was reduced.

[0091] As described above, in Example 2, bioethylene carbonate of electronic grade specifications was efficiently produced on an industrial scale. The bio-based content of the bio-ethylene carbonate obtained in Example 2 was 100%.

[0092] [Example 3] Bioethylene carbonate was purified in the same manner as in Example 2, except that the packing materials in the low boiling point separation column A and the purification column B were Technopack. In Example 3, low boiling point separation column A was made of stainless steel and had 25 theoretical plates. Bioethylene carbonate was introduced into low boiling point separation column A from the 14th theoretical plate from the top. Purification column B was made of stainless steel, had 9 theoretical plates, and had a side outlet. The bottom component (Ab) of low boiling point separation column A was introduced into purification column B from the 7th theoretical plate from the top. In purification column B, the side outlet was located at the 3rd theoretical plate from the top.

[0093] Bioethylene carbonate was introduced into low-boiling separation column A at a flow rate of 5,330 kg / hour. The withdrawal rate of low-boiling components (top component (At)) from the top of low-boiling separation column A was 495 kg / hour. A bottom component (Ab) containing bioethylene carbonate with a purity of 99.75 mass% was withdrawn from the bottom of low-boiling separation column A at a rate of 4,845 kg / hour and introduced into purification column B. In purification column B, the withdrawal rate of low-boiling components (top component (Bt)) from the top was 95 kg / hour, and the withdrawal rate of high-boiling components (bottom component (Bb)) from the bottom was 45 kg / hour. In addition, in purification column B, bioethylene carbonate was withdrawn as a side cut component (Bs) from a side outlet at a rate of 4,715 kg / hour (BsV = 4.715 t / hour). In purification column B, the bioethylene carbonate withdrawn from the side outlet had a purity of 99.994% by mass, a DEG concentration of 18 ppm by mass, ethylene oxide and ethylene glycol contents each of which was 30 ppm by mass or less, a water content of 20 ppm by mass or less, and each of the nine metal components, sodium, potassium, copper, iron, lead, zinc, chromium, nickel, and calcium, of 1 μg / mL or less, thereby satisfying the specifications for use as an electrolyte (electronic grade specifications).

[0094] The operating conditions of the low boiling point separation column A were a reflux ratio of 14.9, a column top reflux amount of 7400 kg / hour, and a column bottom temperature of 124° C. The steam consumption in the reboiler of the low boiling point separation column A was 3200 kg / hour. The operation conditions of the purification column B were a reflux ratio of 66.3, a column top reflux amount of 6,300 kg / hour, and a column bottom temperature of 124° C. The amount of steam used in the reboiler of the purification column B was 2,400 kg / hour.

[0095] Furthermore, in the steady state of continuous operation of bioethylene carbonate purification in Example 3, when the amount of liquid held at the bottoms of the main column of low boiling separation column A (L) is defined as VA, the amount of liquid held at the bottoms of the main column of purification column B (L) is defined as VB, the amount of side cut component (Bs) withdrawn (t / hour) is defined as BsV, the inner diameter (cm) of the column main body of low boiling separation column A is defined as DA, the inner diameter (cm) of the column pot of low boiling separation column A is defined as Da, the inner diameter (cm) of the column main body of purification column B is defined as DB, and the inner diameter (cm) of the column pot of purification column B is defined as Db, VA / BsV was 73, VB / BsV was 73, Da / BsV was 19, Db / BsV was 19, DA / Da was 4.4, and DB / Db was 4.

[0096] In Example 3, bioethylene carbonate was continuously introduced into low-boiling separation column A, and without side-cut withdrawal, low-boiling components (column top component (At)) and a column bottom component (Ab) containing bioethylene carbonate were continuously withdrawn and separated by distillation. This method specialized low-boiling separation column A (first column) for removing low-boiling components, thereby enabling a shorter column height and reduced capital investment. Furthermore, specializing low-boiling separation column A for removing low-boiling components created a margin in column load, enabling sufficient separation to produce bioethylene carbonate of specifications equivalent to industrial grade, with a purity of 99.5% by mass. The column bottom component (Ab) was then continuously introduced into purification column B, which has a side withdrawal port, and bioethylene carbonate was withdrawn from the side withdrawal port. This enabled the removal of traces of low-boiling and high-boiling components, enabling the production of electronic-grade ethylene carbonate. Furthermore, since most of the low boiling point components were removed in the low boiling point separation tower A (first tower), there was room for the tower load in the purification tower B (second tower), and the energy consumption for separation could be reduced. Furthermore, since the tower load in the purification tower B was not increased, the pressure loss in the tower could be reduced and the tower bottom temperature could be lowered, which reduced the amount of low boiling point by-products and high boiling point by-products produced by decomposition and polymerization reactions, and as a result, the amount of waste was reduced.

[0097] As described above, in Example 3, bioethylene carbonate of electronic grade specifications was efficiently produced on an industrial scale. The bio-based content of the bioethylene carbonate obtained in Example 3 was 98%.

[0098] [Example 4] Bioethylene carbonate was purified in the same manner as in Example 2, except that the packing materials in the low boiling point separation column A and the purification column B were changed to Melapack. In Example 4, low boiling point separation column A was made of stainless steel and had 25 theoretical plates. Bioethylene carbonate was introduced into low boiling point separation column A from the 14th theoretical plate from the top. Purification column B was made of stainless steel, had 9 theoretical plates, and had a side outlet. The bottom component (Ab) of low boiling point separation column A was introduced into purification column B from the 7th theoretical plate from the top. In purification column B, the side outlet was located at the 3rd theoretical plate from the top.

[0099] Bioethylene carbonate was introduced into low-boiling separation column A at a flow rate of 5,340 kg / hour. The withdrawal rate of low-boiling components (top component (At)) from the top of low-boiling separation column A was 510 kg / hour. A bottom component (Ab) containing bioethylene carbonate with a purity of 99.72 mass% was withdrawn from the bottom of low-boiling separation column A at a rate of 4,840 kg / hour and introduced into purification column B. In purification column B, the withdrawal rate of low-boiling components (top component (Bt)) from the top was 95 kg / hour, and the withdrawal rate of high-boiling components (bottom component (Bb)) from the bottom was 50 kg / hour. In addition, in purification column B, bioethylene carbonate was withdrawn as a side cut component (Bs) from a side outlet at a rate of 4,690 kg / hour (BsV = 4.695 t / hour). In purification column B, the ethylene carbonate withdrawn from the side outlet had a purity of 99.992% by mass, a DEG concentration of 25 ppm by mass, ethylene oxide and ethylene glycol contents each of which was 30 ppm by mass or less, a water content of 20 ppm by mass or less, and each of the nine metal components, namely sodium, potassium, copper, iron, lead, zinc, chromium, nickel, and calcium, being 1 μg / mL or less, thereby satisfying the specifications for use as an electrolyte (electronic grade specifications).

[0100] The operation conditions of the low boiling point separation column A were a reflux ratio of 14.5, a column top reflux amount of 7400 kg / hour, and a column bottom temperature of 128° C. The steam consumption in the reboiler of the low boiling point separation column A was 3200 kg / hour. The operation conditions of the purification column B were a reflux ratio of 66.3, a column top reflux amount of 6,300 kg / hour, and a column bottom temperature of 126° C. The amount of steam used in the reboiler of the purification column B was 2,400 kg / hour.

[0101] Furthermore, in the steady state of continuous operation of bioethylene carbonate purification in Example 4, when the amount of liquid held at the bottoms of the main body of low boiling separation column A (L) is VA, the amount of liquid held at the bottoms of the main body of purification column B (L) is VB, the amount of side cut component (Bs) withdrawn (t / hour) is BsV, the inner diameter (cm) of the main body of low boiling separation column A is DA, the inner diameter (cm) of the column pot of low boiling separation column A is Da, the inner diameter (cm) of the main body of purification column B is DB, and the inner diameter (cm) of the column pot of purification column B is Db, VA / BsV was 53, VB / BsV was 53, Da / BsV was 19, Db / BsV was 19, DA / Da was 4.4, and DB / Db was 4.

[0102] In Example 4, bioethylene carbonate was continuously introduced into low-boiling separation column A, and without side-cut withdrawal, low-boiling components (column top component (At)) and a column bottom component (Ab) containing bioethylene carbonate were continuously withdrawn and separated by distillation. This method specialized low-boiling separation column A (first column) for removing low-boiling components, thereby shortening the column height and reducing capital investment. Furthermore, specializing low-boiling separation column A for removing low-boiling components created a margin in column load, enabling sufficient separation to produce bioethylene carbonate of industrial-grade purity (99.5% by mass). The column bottom component (Ab) was then continuously introduced into purification column B, which has a side withdrawal port, and ethylene carbonate was withdrawn from the side withdrawal port. This enabled removal of traces of low-boiling and high-boiling components, enabling the production of electronic-grade bioethylene carbonate. Furthermore, since most of the low boiling point components were removed in the low boiling point separation tower A (first tower), there was room for the tower load in the purification tower B (second tower), and the energy consumption for separation could be reduced. Furthermore, since the tower load in the purification tower B was not increased, the pressure loss in the tower could be reduced and the tower bottom temperature could be lowered, which reduced the amount of low boiling point by-products and high boiling point by-products produced by decomposition and polymerization reactions, and as a result, the amount of waste was reduced.

[0103] As described above, in Example 4, bioethylene carbonate of electronic grade specifications was efficiently produced on an industrial scale. The bio-based content of the bioethylene carbonate obtained in Example 4 was 99%.

[0104] [Comparative Example 1] Fossil fuel-derived ethylene carbonate was produced using the same equipment and under the same production conditions as in Example 1, except that ethylene oxide produced from fossil fuel-derived ethylene and having a bio-based content of 0% was used instead of bioethylene oxide, and carbon dioxide produced as a by-product during the production of ethylene oxide was collected, purified, and used. The biobased content of the ethylene carbonate obtained in Comparative Example 1 was 0%.

[0105] Comparative Example 2 Fossil fuel-derived ethylene carbonate was produced using the same apparatus and under the same production conditions as in Example 2, except that the ethylene carbonate produced in Comparative Example 1 was used. The resulting fossil-fuel-derived ethylene carbonate met all electronic-grade specifications. The biobased content of the ethylene carbonate obtained in Comparative Example 2 was 0%. [Industrial Applicability]

[0106] The method for producing bioethylene carbonate of this embodiment can efficiently produce ethylene carbonate with reduced environmental impact. Furthermore, the method for producing electronic-grade bioethylene carbonate of this embodiment can efficiently produce electronic-grade bioethylene carbonate. Furthermore, the ethylene carbonate obtained by the production method of this embodiment is useful, for example, as an electrolyte for lithium batteries. [Explanation of symbols]

[0107] A: low boiling point separation column, B: bioethylene carbonate purification column, A2: top condenser of low boiling point separation column A, A5: reboiler of low boiling point separation column A, B2: top condenser of bioethylene carbonate purification column B, B5: reboiler of bioethylene carbonate purification column B, 1: carbon dioxide supply pump, 2: bioethylene oxide pump, 3: catalyst supply pump, 4: carbon dioxide evaporator, 5, 6, 7, 8, 11, 12, 15, 18, 19, 21, 22, 24, 25, 26: piping, 9: reactor circulation pump, 10: reactor, 13: reactor circulation flow meter, 14: heat exchanger, 16: reactor temperature control valve, 17: flow meter, 20: control valve, 23: reactor vent gas control valve, t1, t2, T1, T2: thermometers.

Claims

1. an ethylene carbonate production step of producing ethylene carbonate by reacting bio-derived ethylene oxide with carbon dioxide by-produced in the production of bio-derived ethylene oxide; a first distillation separation step and a second distillation separation step subsequent to the ethylene carbonate production step; and the first distillation separation step is a step of continuously introducing ethylene carbonate obtained in the ethylene carbonate production step into a low-boiling point separation column A, and continuously withdrawing from the low-boiling point separation column A a top component (At) from the column top and a bottom component (Ab) containing ethylene carbonate from the column bottom, The second distillation separation step is a step of continuously introducing the bottom component (Ab) obtained in the first distillation separation step into a purification column B having a side cut outlet, and continuously withdrawing three components from the purification column B: a top component (Bt) from the top of the column, a side cut component (Bs) from the side cut outlet, and a bottom component (Bb) from the bottom of the column; The side cut component (Bs) is ethylene carbonate having a purity of 99.97% by mass or more. A method for producing bio-based ethylene carbonate with a bio-based content of 95 to 100% as measured in accordance with ASTM D6866.

2. 2. The method according to claim 1, wherein the amount of liquid held at the bottom of the main column of the low boiling separation column A (L) is VA, the amount of liquid held at the bottom of the main column of the purification column B (L) is VB, and the amount of side cut component (Bs) withdrawn per hour (t) is BsV, the conditions of the following formulas (1) and (2) are satisfied. 10≦VA / BsV≦1000 (1) 10≦VB / BsV≦1000 (2)

3. 3. The method according to claim 1 or 2, wherein the inner diameter (cm) of the column pot of the low boiling separation column A is Da, the inner diameter (cm) of the column pot of the purification column B is Db, and the amount (t) of the side cut component (Bs) extracted per hour is BsV, the conditions of the following formulas (3) and (4) are satisfied. 10≦Da / BsV≦50 (3) 10≦Db / BsV≦50 (4)

4. When the inner diameter (cm) of the column body of the low boiling separation column A is DA, the inner diameter (cm) of the column pot of the low boiling separation column A is Da, the inner diameter (cm) of the column body of the purification column B is DB, and the inner diameter (cm) of the column pot of the purification column B is Db, the production method according to any one of claims 1 to 3, which satisfies the conditions of the following formulas (5) and (6). 2≦DA / Da≦10 (5) 2≦DB / Db≦10 (6)

5. The production method according to any one of claims 1 to 4, wherein the reboiler type of the low boiling separation column A and / or the purification column B is a forced circulation type, a cross pipe falling film type, or a thin film evaporation type.

6. The low boiling point separation column A and / or the purification column B have packing, and the packing is structured packing, The manufacturing method according to any one of claims 1 to 5, wherein the structured packing is any one of Melapak, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, Glitchgrid, and gauze packing.

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