Method for industrially manufacturing dialkyl carbonates and diols

Abstract

The objective of the present invention is to provide a specific method for industrially producing dialkyl carbonates and diols with high productivity, long-term stability, high selectivity, and high yield, using cyclic carbonates and aliphatic monohydric alcohols as raw materials. A method for industrially producing dialkyl carbonates and diols that satisfies specific requirements by using cyclic carbonates and aliphatic monohydric alcohols as raw materials, continuously supplying these raw materials into a continuous multi-stage distillation column where a homogeneous catalyst is present, and simultaneously performing reaction and distillation within the column, wherein a low-boiling point reaction mixture containing dialkyl carbonates produced is continuously discharged in a gaseous state from the top of the column, and a high-boiling point reaction mixture containing diols is continuously discharged in a liquid state from the bottom of the column.

Description

Technology Field

[0001] The present invention relates to a method for industrially manufacturing dialkyl carbonates and diols. Background Technology

[0002] As a method for industrially manufacturing dialkyl carbonates and diols, for example, Patent Document 1 proposes a method and apparatus that can stably produce dialkyl carbonates and diols with high yield over a long period (e.g., 5,000 hours or more) with high selectivity and high productivity by using cyclic carbonates and aliphatic monohydric alcohols as raw materials, continuously supplying these raw materials into a continuous multi-stage distillation column where a homogeneous catalyst is present, and simultaneously performing reaction and distillation within the column by a reaction distillation method. Prior art literature

[0003] [Patent Document 1] International Publication No. 2007 / 069514 The problem to be solved

[0004] However, the method and apparatus described in Patent Document 1 may not have sufficient productivity of dialkyl carbonates and diols for the scale of the apparatus.

[0005] Therefore, the problem that the present invention aims to solve is to provide a specific method for industrially producing dialkyl carbonates and diols in large quantities using a reaction distillation method in which cyclic carbonates and aliphatic monohydric alcohols are used as raw materials, and the raw materials are continuously supplied into a continuous multi-stage distillation column where a homogeneous catalyst is present, and reaction and distillation are performed simultaneously within the column, thereby enabling stable production with higher productivity (e.g., dialkyl carbonates at least 4.5 tons per hour, diols at least 2.7 tons per hour) for a long period (e.g., 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more) with high selectivity and high yield. means of solving the problem

[0006] The inventors, as a result of careful consideration to solve the above-mentioned problem, discovered that by setting the length and inner diameter of the tower and the ratio of the active area and the ratio of the open area of ​​each stage tray inside the tower to a specific range, it is possible to stably produce dialkyl carbonates and diols in large quantities for industrial production with the same tower length and inner diameter, with a high selectivity and high yield for a long period (e.g., 1,000 hours or more, preferably 3,000 hours or more, more preferably 5,000 hours or more) and with higher productivity (e.g., 1.3 times or more of the target values ​​described in Patent Document 1 (2 tons or more of dialkyl carbonates per hour, 1.3 tons or more of diols per hour) (i.e., 4.5 tons or more of dialkyl carbonates per hour, 2.7 tons or more of diols per hour)), and thus arrived at the present invention.

[0007] That is, the present invention is as follows.

[0008] [1]

[0009] In a reactive distillation method in which cyclic carbonates and aliphatic monohydric alcohols are used as raw materials, these raw materials are continuously fed into a continuous multi-stage distillation column where a homogeneous catalyst is present, and reaction and distillation are performed simultaneously within the column, thereby continuously discharging a low-boiling point reaction mixture containing dialkyl carbonates produced from the top of the column as a gas and continuously discharging a high-boiling point reaction mixture containing diols from the bottom of the column as a liquid, the

[0010] (a) The above continuous multi-stage distillation column has a cylindrical body with a length L (cm) and an inner diameter D (cm) and has a structure having an internal, and the internal is a tray-type distillation column having a plurality of holes, and has a gas outlet at the top of the column or near the top of the column, a liquid outlet at the bottom of the column or near the bottom of the column, one or more first inlets at the top and / or middle of the column below the gas outlet, and one or more second inlets at the middle and / or bottom of the column above the liquid outlet.

[0011] (1) The length L(cm) of the tower satisfies Equation (1), and

[0012] 1,500≤L≤12,000 Equation (1)

[0013] (2) The inner diameter D(cm) of the tower satisfies Equation (2), and

[0014] 120≤D≤3,000 Equation (2)

[0015] (3) The above internal consists of three types of trays: top, middle, and bottom, and

[0016] (4) The cyclic carbonate raw material is continuously introduced into the continuous multi-stage distillation column from one or more of the first inlets, and the top is a stage above the uppermost inlet of the one or more of the first inlets, and the ratio of the number of trays in the top is 1 to 10% of the total number of stages, and

[0017] (5) The raw material, an aliphatic monohydric alcohol, is continuously introduced into the continuous multi-stage distillation column from one or more of the second inlets, and the stage is from the uppermost inlet of one or more of the second inlets to the uppermost inlet of one or more of the first inlets, and the ratio of the number of trays in the stage is 40 to 50% of the total number of stages, and

[0018] (6) The bottom is a lower section than the uppermost section among one or more of the second sections, and the ratio of the number of trays in the bottom is 45 to 55% of the total number of sections, and

[0019] (7) For each tray at the bottom, the ratio of the active area calculated in the following formula (i) is 40 to 80%, and the ratio of the open area calculated in the following formula (ii) is 1.0 to 5.0%, and

[0020] Ratio of active area (%) = Active area (㎠) / Tray area (㎠) × 100 ...(i)

[0021] (In Equation (i), the active area refers to the area of ​​the perforated section of the tray deck (the range extending 4 inches further outward from the boundary of the minimum section containing all perforations), and the tray area refers to the area of ​​the tray deck, which includes the active area but excludes the downcomer section.)

[0022] Ratio of open area (%) = Open area (㎠) / Active area (㎠) × 100 ...(ii)

[0023] (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area refers to the same as Equation (i).)

[0024] (8) In each of the upper and middle trays, the ratio of the active area calculated in equation (i) is 40 to 80%, and the ratio of the open area calculated in equation (ii) is at least 1.0 times the ratio of the open area calculated in equation (ii) in each of the lower trays.

[0025] (9) A method for industrially producing dialkyl carbonates and diols, wherein the homogeneous catalyst is composed of a mixture of alkali metal and ethylene glycol, the mass ratio of alkali metal to ethylene glycol (alkali metal / ethylene glycol) in the homogeneous catalyst is 0.05 to 0.5, and the catalyst concentration (calculated as alkali metal concentration) is 0.05 to 2.0 mass% with respect to the cyclic carbonate supplied to the distillation column.

[0026] [2]

[0027] At the top, the gas flow rate is 5,000–45,000 kg / hour, and the liquid flow rate is 1,000–15,000 kg / hour, and

[0028] In the interruption, the gas flow rate is 5,000–30,000 kg / hour, and the liquid flow rate is 1,000–15,000 kg / hour, and

[0029] The method described in claim 1, wherein, at the bottom, the gas flow rate is 5,000 to 20,000 kg / hour and the liquid flow rate is 1,000 to 30,000 kg / hour.

[0030] [3]

[0031] The method described in [1] or [2], in which the amount of dialkyl carbonate produced is 4.5 tons or more per hour.

[0032] [4]

[0033] A method described in any one of [1] to [3] in which the amount of diols produced is 2.5 tons or more per hour.

[0034] [5]

[0035] As a continuous multi-stage distillation column for carrying out the transesterification reaction and distillation of cyclic carbonates and aliphatic monohydric alcohols,

[0036] (a) A cylindrical body with length L (cm) and inner diameter D (cm), and

[0037] A tray having a plurality of holes arranged internally within the body portion, and

[0038] A gas outlet at the top of the tower or at the top of the tower near it, and

[0039] A liquid outlet at the bottom of the tower or at the lower part of the tower near it, and

[0040] One or more first inlets located below the above gas outlet and in the upper and / or middle part of the tower, and

[0041] One or more second inlets are provided above the liquid outlet and in the middle and / or lower part of the tower, and

[0042] (1) The length L(cm) of the tower satisfies Equation (1), and

[0043] 1,500≤L≤12,000 Equation (1)

[0044] (2) The inner diameter D(cm) of the tower satisfies Equation (2), and

[0045] 120≤D≤3,000 Equation (2)

[0046] (3) The above internal consists of three types of trays: top, middle, and bottom, and

[0047] (4) The cyclic carbonate raw material is continuously introduced into the continuous multi-stage distillation column from one or more of the first inlets, and the top is a stage above the uppermost inlet of the one or more of the first inlets, and the ratio of the number of trays in the top is 1 to 10% of the total number of stages, and

[0048] (5) The raw material, an aliphatic monohydric alcohol, is continuously introduced into the continuous multi-stage distillation column from one or more of the second inlets, and the stage is from the uppermost inlet of one or more of the second inlets to the uppermost inlet of one or more of the first inlets, and the ratio of the number of trays in the stage is 40 to 50% of the total number of stages, and

[0049] (6) The bottom is a lower section than the uppermost section among one or more of the second sections, and the ratio of the number of trays in the bottom is 45 to 55% of the total number of sections, and

[0050] (7) For each tray at the bottom, the ratio of the active area calculated in the following formula (i) is 40 to 80%, and the ratio of the open area calculated in the following formula (ii) is 1.0 to 5.0%, and

[0051] Ratio of active area (%) = Active area (㎠) / Tray area (㎠) × 100 ...(i)

[0052] (In Equation (i), the active area refers to the area of ​​the perforated section of the tray deck (the range extending 4 inches further outward from the boundary of the minimum section containing all perforations), and the tray area refers to the area of ​​the tray deck, which includes the active area but excludes the downcomer section.)

[0053] Ratio of open area (%) = Open area (㎠) / Active area (㎠) × 100 ...(ii)

[0054] (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area refers to the same as Equation (i).)

[0055] (8) A continuous multi-stage distillation column in which, in each of the upper and middle stage trays, the ratio of the active area calculated in Equation (i) is 40 to 80%, and the ratio of the open area calculated in Equation (ii) is at least 1.0 times the ratio of the open area calculated in Equation (ii) in each of the lower stage trays. Effects of the invention

[0056] The present invention enables the industrial mass production of dialkyl carbonates and diols with the same tower length and inner diameter, with stable and higher productivity (e.g., at least 1.3 times the target values ​​described in Patent Document 1 (at least 2 tons of dialkyl carbonates per hour and at least 1.3 tons of diols per hour) (i.e., at least 4.5 tons of dialkyl carbonates per hour and at least 2.7 tons of diols per hour)) and can be produced stably for a long period (e.g., at least 1,000 hours, preferably at least 3,000 hours, more preferably at least 5,000 hours) with high selectivity and high yield. Brief explanation of the drawing

[0057] [Fig. 1] This is a drawing illustrating an example of a manufacturing apparatus used for the production of dialkyl carbonates and diols according to the present invention. [Fig. 2] This is a conceptual diagram illustrating an example of a tray structure inside a continuous multi-stage distillation column used in the present invention. Specific details for implementing the invention

[0058] The following describes in more detail the forms for carrying out the present invention (hereinafter referred to as "the present embodiments"), but the present invention is not limited thereto and can be modified in various ways without departing from the gist thereof.

[0059] The method for industrially producing dialkyl carbonates and diols according to the present embodiment is to continuously produce dialkyl carbonates and diols by a reactive distillation method in which cyclic carbonates and aliphatic monohydric alcohols are used as raw materials, the raw materials are continuously supplied into a continuous multi-stage distillation column where a homogeneous catalyst is present, and reaction and distillation are performed simultaneously within the column, thereby continuously discharging a low-boiling point reaction mixture containing dialkyl carbonates produced from the top of the column in a gaseous state and continuously discharging a high-boiling point reaction mixture containing diols from the bottom of the column in a liquid state.

[0060] (a) The above continuous multi-stage distillation column has a cylindrical body with a length L (cm) and an inner diameter D (cm) and has a structure having an internal, and the internal is a tray-type distillation column having a plurality of holes, and has a gas outlet at the top of the column or near the top of the column, a liquid outlet at the bottom of the column or near the bottom of the column, one or more first inlets at the top and / or middle of the column below the gas outlet, and one or more second inlets at the middle and / or bottom of the column above the liquid outlet.

[0061] (1) The length L(cm) of the tower satisfies Equation (1), and

[0062] 1,500≤L≤12,000 Equation (1)

[0063] (2) The inner diameter D(cm) of the tower satisfies Equation (2), and

[0064] 120≤D≤3,000 Equation (2)

[0065] (3) The above internal consists of three types of trays: top, middle, and bottom, and

[0066] (4) The cyclic carbonate raw material is continuously introduced into the continuous multi-stage distillation column from one or more of the first inlets, and the top is a stage above the uppermost inlet of the one or more of the first inlets, and the ratio of the number of trays in the top is 1 to 10% of the total number of stages, and

[0067] (5) The raw material, an aliphatic monohydric alcohol, is continuously introduced into the continuous multi-stage distillation column from one or more of the second inlets, and the stage is from the uppermost inlet of one or more of the second inlets to the uppermost inlet of one or more of the first inlets, and the ratio of the number of trays in the stage is 40 to 50% of the total number of stages, and

[0068] (6) The bottom is a lower section than the uppermost section among one or more of the second sections, and the ratio of the number of trays in the bottom is 45 to 55% of the total number of sections, and

[0069] (7) For each tray at the bottom, the ratio of the active area calculated in the following formula (i) is 40 to 80%, and the ratio of the open area calculated in the following formula (ii) is 1.0 to 5.0%, and

[0070] Ratio of active area (%) = Active area (㎠) / Tray area (㎠) × 100 ...(i)

[0071] (In Equation (i), the active area refers to the area of ​​the perforated section of the tray deck (the range extending 4 inches further outward from the boundary of the minimum section containing all perforations), and the tray area refers to the area of ​​the tray deck, which includes the active area but excludes the downcomer section.)

[0072] Ratio of open area (%) = Open area (㎠) / Active area (㎠) × 100 ...(ii)

[0073] (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area refers to the same as Equation (i).)

[0074] (8) In each of the upper and middle trays, the ratio of the active area calculated in equation (i) is 40 to 80%, and the ratio of the open area calculated in equation (ii) is at least 1.0 times the ratio of the open area calculated in equation (ii) in each of the lower trays.

[0075] (9) The above homogeneous catalyst is composed of a mixture of alkali metal and ethylene glycol, and the mass ratio of alkali metal to ethylene glycol (alkali metal / ethylene glycol) in the above homogeneous catalyst is 0.05 to 0.5, and the catalyst concentration (calculated as alkali metal concentration) is 0.05 to 2.0 mass% with respect to the cyclic carbonate supplied to the distillation column.

[0076] By having the above-described configuration, the manufacturing method of the present embodiment allows for the industrial production of dialkyl carbonates and diols with stable and higher productivity (e.g., dialkyl carbonates at least 4.5 tons per hour, diols at least 2.7 tons per hour) and stable production with high selectivity and high yield over a long period (e.g., 1,000 hours or more, preferably 3,000 hours or more, more preferably 5,000 hours or more).

[0077] The reaction used in the manufacturing method of the present embodiment is a reversible equilibrium ester exchange reaction represented by the following formula, in which a dialkyl carbonate (C) and a diol (D) are produced from a cyclic carbonate (A) and an aliphatic monohydric alcohol (B).

[0078]

[0079] (during food, R lIt represents a divalent group -(CH2)m- (where m is an integer from 2 to 6), and one or more hydrogens may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms. In addition, R 2 ...represents a monovalent aliphatic group having 1 to 12 carbon atoms, and one or more hydrogen atoms may be substituted with an alkyl group or an aryl group having 1 to 10 carbon atoms.

[0080] In the manufacturing method of the present embodiment, the cyclic carbonate used as a raw material is a compound represented by (A) in the above formula. As for the cyclic carbonate, alkylene carbonates such as ethylene carbonate and propylene carbonate, or 1,3-dioxacyclohexa-2-one and 1,3-dioxacyclohepta-2-one are preferably used, and ethylene carbonate and propylene carbonate are more preferably used due to ease of availability, and ethylene carbonate is particularly preferably used.

[0081] In addition, the aliphatic monohydric alcohol, which is another raw material, is a compound represented by (B) in the above formula. As for the aliphatic monohydric alcohol, it is preferable to use one with a boiling point lower than that of the resulting diol. Therefore, as for aliphatic monohydric alcohols, although they may vary depending on the type of cyclic carbonate used, for example methanol, ethanol, propanol (each isomer), allyl alcohol, butanol (each isomer), 3-buten-1-ol, amyl alcohol (each isomer), ε-xyl alcohol (each isomer), ε-butyl alcohol (each isomer), octyl alcohol (each isomer), nonyl alcohol (each isomer), decyl alcohol (each isomer), undecyl alcohol (each isomer), dodecyl alcohol (each isomer), cyclopentanol, cyclo-xanol, cyclo-butanol, cyclooctanol, methylcyclopentanol (each isomer), ethylcyclopentanol (each isomer), methylcyclo-xanol (each isomer), ethylcyclo-xanol (each isomer), Examples include dimethylcycloxanol (each isomer), diethylcycloxanol (each isomer), phenylcycloxanol (each isomer), benzyl alcohol, phenethyl alcohol (each isomer), phenylpropanol (each isomer), etc. In addition, these aliphatic monohydric alcohols may be substituted with substituents such as halogens, lower alkoxy groups, cyano groups, alkoxycarbonyl groups, aryloxycarbonyl groups, acyloxy groups, nitro groups, etc.

[0082] Among these aliphatic monohydric alcohols, alcohols having 1 to 6 carbon atoms are preferably used, and more preferably alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, propanol (each isomer), and butanol (each isomer). When ethylene carbonate or propylene carbonate is used as a cyclic carbonate, methanol and ethanol are preferred, and methanol is particularly preferred.

[0083] In the manufacturing method of the present embodiment, the raw material, a cyclic carbonate, is continuously introduced into a continuous multi-stage distillation column from one or more first inlets, and the raw material, an aliphatic monohydric alcohol, is continuously introduced into a continuous multi-stage distillation column from one or more second inlets. By continuously introducing each raw material into the continuous multi-stage distillation column at these locations, optimal reaction efficiency of the dialkyl carbonate and diols can be achieved to secure a sufficient production volume, and optimal separation performance can also be achieved to secure a sufficient amount of the dialkyl carbonate and diols.

[0084] In the manufacturing method of the present embodiment, a homogeneous catalyst is present in a reaction distillation column. Any method may be used to present the homogeneous catalyst, but it is preferable to present the catalyst in a liquid state within the reaction distillation column by continuously supplying the catalyst into the reaction distillation column.

[0085] When a homogeneous catalyst is continuously supplied into a reaction distillation column, it may be supplied simultaneously with cyclic carbonates and / or aliphatic monohydric alcohols, or supplied at a location different from the raw material. Since the reaction actually proceeds in the region below the catalyst supply location within the distillation column, it is preferable to supply the catalyst to the region between the top of the column and the raw material supply location. Furthermore, it is preferable that there are at least 5 stages where the catalyst is present, more preferably at least 7 stages, and even more preferably at least 10 stages.

[0086] The catalyst used in the manufacturing method of the present embodiment is a compound composed of a mixture of an alkali metal and ethylene glycol. In addition, the mass ratio of the alkali metal to the ethylene glycol (alkali metal / ethylene glycol) in the homogeneous catalyst is 0.05 to 0.5, preferably 0.1 to 0.4, and more preferably 0.2 to 0.3. If the mass ratio of the alkali metal to the ethylene glycol (alkali metal / ethylene glycol) is within the above range, the formation of dialkyl carbonates and diols can be promoted, while the formation of impurities can be suppressed. Furthermore, the catalyst concentration (converted to alkali metal concentration) with respect to the cyclic carbonate (e.g., ethylene carbonate (EC)) supplied to the distillation column is 0.05 to 2.0 mass%.

[0087] The alkali metal used in the manufacturing method of the present embodiment is not particularly limited, but examples include lithium, potassium, sodium, and cesium, and preferably potassium and sodium.

[0088] The amount of catalyst used in the manufacturing method of the present embodiment (converted to alkali metal concentration) is typically 0.05 to 2.0 mass% when expressed as a ratio to the mass of the cyclic carbonate that is the feedstock, preferably 0.1 to 1.0 mass%, and more preferably 0.5 to 1.0 mass%.

[0089] If the amount of catalyst is above the above lower limit, the reaction and yield become sufficient, thereby improving production volume. Furthermore, if the amount of catalyst is below the above upper limit, impurities (high-boiling point components) are suppressed, thereby improving product purity. Additionally, it is possible to prevent a portion of the catalyst from escaping the system along with impurities (high-boiling point components), thus reducing catalyst loss.

[0090] In the manufacturing method of the present embodiment, when continuously supplying cyclic carbonates to a reactive distillation column, such as a continuous multi-stage distillation column (e.g., number of stages n), it is preferable to supply them to a specific stage. For example, the cyclic carbonates, which are raw materials, are preferably introduced into the continuous multi-stage distillation column from one or more inlets provided between the third stage from the top of the column and the (n / 3)th stage. It is preferable that the stages above the cyclic carbonate inlets ensure that high-boiling point compounds, such as cyclic carbonates and diols, are not included in the top-of-the-column components. In this sense, it is preferable that there are three or more stages above the cyclic carbonate inlets, more preferably four to ten stages, and even more preferably five to eight stages.

[0091] In the manufacturing method of the present embodiment, the internal of the continuous multi-stage distillation column consists of three types of trays: upper, middle, and lower.

[0092] The top is a step above the top of the uppermost of one or more first inlets, the middle is a step from the top of the uppermost of one or more second inlets to the top of the uppermost of one or more first inlets, and the bottom is a step below the top of the uppermost of one or more second inlets.

[0093] In the manufacturing method of the present embodiment, the total number of stages n of the upper, middle, and lower sections is preferably 10 to 100 stages, more preferably 30 to 100 stages, and even more preferably 30 to 80 stages.

[0094] In addition, in the manufacturing method of the present embodiment, the ratio of the number of trays in the upper section is 1 to 10% of the total number of sections, preferably 3 to 10%, and more preferably 5 to 10%. In addition, the ratio of the number of trays in the middle section is 40 to 50% of the total number of sections, preferably 40 to 45%, and more preferably 40 to 43%. In addition, the ratio of the number of trays in the lower section is 45 to 55% of the total number of sections, preferably 48 to 55%, and more preferably 50 to 55%. By setting the ratios of the upper, middle, and lower sections to the above ranges, optimal reaction efficiency between dialkyl carbonates and diols can be achieved to ensure sufficient production volume, and optimal separation performance can be achieved to ensure sufficient dialkyl carbonates and diols.

[0095] The preferred cyclic carbonate used in the present embodiment is a halogen-free cyclic carbonate produced by the reaction of carbon dioxide with an alkylene oxide, such as ethylene oxide, propylene oxide, or styrene oxide. Accordingly, a cyclic carbonate containing a small amount of these raw materials or diols may be used as a raw material for the present embodiment. The cyclic carbonate may be derived from biomass. For example, a cyclic carbonate obtained using bioethanol as a raw material may be used.

[0096] In the present embodiment, the aliphatic monohydric alcohol used as a raw material may be a high-purity aliphatic monohydric alcohol or an aliphatic monohydric alcohol containing other compounds. Specifically, for example, an aliphatic monohydric alcohol containing 1 to 15 mass% of dialkyl carbonate with respect to the total mass of the aliphatic monohydric alcohol and the dialkyl carbonate is preferably used, an aliphatic monohydric alcohol containing 1.5 to 12 mass% of dialkyl carbonate is more preferably used, and even more preferably, an aliphatic monohydric alcohol containing 2 to 10 mass% of dialkyl carbonate is used.

[0097] When carrying out this reaction industrially, it is desirable to use a material consisting mainly of a cyclic carbonate and / or aliphatic monohydric alcohol recovered from this process and / or another process as a raw material, in addition to the cyclic carbonate and / or aliphatic monohydric alcohol newly introduced into the reaction system. The manufacturing method of the present embodiment makes this possible, and this is one of the excellent features of the manufacturing method of the present embodiment. The other process is not particularly limited, but, for example, may be a process for producing a diaryl carbonate from a dialkyl carbonate and an aromatic monohydroxy compound. In this process, an aliphatic monohydric alcohol is produced as a byproduct and recovered. This recovered byproduct aliphatic monohydric alcohol typically contains a dialkyl carbonate, but if the content is within the range described above, the excellent effects of the manufacturing method of the present embodiment can be further exhibited. Furthermore, this recovered byproduct aliphatic monohydric alcohol may contain aromatic monohydroxy compounds, alkylaryl ethers, small amounts of alkylaryl carbonates, diaryl carbonates, etc. In the manufacturing method of the present embodiment, this byproduct aliphatic monohydric alcohol may be used as a raw material as is, or it may be used as a raw material after reducing the amount of a contained substance with a boiling point higher than that of the aliphatic monohydric alcohol by distillation or the like.

[0098] In the manufacturing method of the present embodiment, when continuously supplying an aliphatic monohydric alcohol to a reactive distillation column, such as a continuous multi-stage distillation column (e.g., number of stages n), it is preferable to supply it to a specific stage. For example, in the manufacturing method of the present embodiment, it is preferable that the raw material, an aliphatic monohydric alcohol, be continuously introduced into the continuous multi-stage distillation column from one or more inlets located between the (n / 3)th stage from the top and the (2n / 3)th stage from the top of the continuous multi-stage distillation column. When the aliphatic monohydric alcohol used as a raw material in the manufacturing method of the present embodiment contains a specific amount of dialkyl carbonate, the excellent effects of the manufacturing method of the present embodiment can be further enhanced by making the inlet a specific stage. More preferably, an aliphatic monohydric alcohol is continuously introduced into the continuous multistage distillation column from one or more inlets provided between the (2n / 5)th stage from the top of the continuous multistage distillation column and the (3n / 5)th stage from the top of the continuous multistage distillation column.

[0099] It is preferable that the raw material be continuously supplied to the distillation column in a liquid, gaseous, or liquid-gaseous state. In addition to supplying the raw material to the distillation column in this manner, it is also preferable to additionally supply gaseous raw material intermittently or continuously from the central and / or lower part of the distillation column. Furthermore, it is also preferable to continuously supply a cyclic carbonate in a liquid or gas-liquid mixed state to the distillation column from one or more inlets provided at a stage above the stage where the catalyst is present, and to continuously supply the aliphatic monohydric alcohol in a gaseous and / or liquid state to the distillation column from one or more inlets provided at the stage above the distillation column. Moreover, it is preferable that these raw materials be brought into contact with the catalyst in a region of at least 5 stages, preferably 7 stages, and more preferably 10 stages or more of the distillation column.

[0100] In the manufacturing method of the present embodiment, the ratio of cyclic carbonate to aliphatic monohydric alcohols supplied to the reaction distillation column may vary depending on the type and amount of the ester exchange catalyst and the reaction conditions, but preferably, the aliphatic monohydric alcohols can be supplied in a molar ratio of 0.01 to 1,000 times the supplied cyclic carbonate. To increase the reaction rate of the cyclic carbonate, it is desirable to supply an excess amount of aliphatic monohydric alcohols of at least twice the molar amount; however, if used in excess, it may be necessary to enlarge the equipment. In this sense, the molar ratio of aliphatic monohydric alcohols to cyclic carbonate is preferably 2 to 20, more preferably 3 to 15, and even more preferably 5 to 12. Furthermore, if a large amount of unreacted cyclic carbonate remains, it reacts with the product diols to produce macromers such as dimers and trimers; therefore, when carried out industrially, it is desirable to reduce the remaining amount of unreacted cyclic carbonate as much as possible. In the manufacturing method of the present embodiment, even if this molar ratio is 10 or less, it is possible to make the reaction rate of the cyclic carbonate 98% or more, preferably 99% or more, and more preferably 99.9% or more. This is also one of the features of the manufacturing method of the present embodiment.

[0101] In the manufacturing method of the present embodiment, preferably, more than 4.5 tons of dialkyl carbonate can be continuously produced per hour. To this end, the minimum amount of cyclic carbonate continuously supplied is typically 2.0 p-tons / hour, preferably 1.5 p-tons / hour, and more preferably 1.3 p-tons / hour with respect to the amount of dialkyl carbonate to be produced (p-tons / hour). In a more preferable case, it can be less than 1.0 p-tons / hour.

[0102] FIG. 1 is a schematic diagram illustrating an example of a continuous multi-stage distillation column used in the manufacturing method according to the present embodiment. Here, the continuous multi-stage distillation column (10) used in the manufacturing method of the present embodiment is a shelf-stage distillation column having a structure in which a cylindrical body part (7) with length L (cm) and inner diameter D (cm) has mirror plate parts (5) on the upper and lower sides and an internal having a number of stages n inside, and the internal is a tray having a plurality of holes; a gas outlet (1) with an inner diameter d1 (cm) at the top of the column or at the top of the column near thereto, a liquid outlet (2) with an inner diameter d2 (cm) at the bottom of the column or at the bottom of the column near thereto, a first inlet (3-a, 3-e) which is one or more inlets provided between the top of the continuous multi-stage distillation column and the (n / 3)th stage, and is above the liquid outlet (2) and below the (n / 3)th stage from the top of the continuous multi-stage distillation column, and the Although the continuous multi-stage distillation column has one or more second inlets (3-b, 3-c, 4-a, 4-b) arranged between the top and the (2n / 3)th stage, it is desirable to satisfy various conditions so that, by simultaneously performing both distillation and reaction, it is possible to stably produce dialkyl carbonates and / or diols, preferably 4.5 tons or more per hour and preferably 2.5 tons or more per hour for a long period. Furthermore, since FIG. 1 is one embodiment of the continuous multi-stage distillation column used in the manufacturing method according to the present embodiment, the arrangement of the stage stages is not limited to the configuration shown in FIG. 1.

[0103] The continuous multi-stage distillation column according to the present embodiment combines not only conditions from a simple distillation function but also conditions necessary to stably carry out the reaction at a high reaction rate and a high selectivity. Specifically, the continuous multi-stage distillation column of the present embodiment is a continuous multi-stage distillation column for performing an ester exchange reaction and distillation of a cyclic carbonate and an aliphatic monohydric alcohol, and

[0104] (a) A cylindrical body with length L (cm) and inner diameter D (cm), and

[0105] A tray having a plurality of holes arranged internally within the body portion, and

[0106] A gas outlet at the top of the tower or at the top of the tower near it, and

[0107] A liquid outlet at the bottom of the tower or at the lower part of the tower near it, and

[0108] One or more first inlets located below the above gas outlet and in the upper and / or middle part of the tower, and

[0109] One or more second inlets are provided above the liquid outlet and in the middle and / or lower part of the tower, and

[0110] (1) The length L(cm) of the tower satisfies Equation (1), and

[0111] 1,500≤L≤12,000 Equation (1)

[0112] (2) The inner diameter D(cm) of the tower satisfies Equation (2), and

[0113] 120≤D≤3,000 Equation (2)

[0114] (3) The above internal consists of three types of trays: top, middle, and bottom, and

[0115] (4) The cyclic carbonate raw material is continuously introduced into the continuous multi-stage distillation column from one or more of the first inlets, and the top is a stage above the uppermost inlet of the one or more of the first inlets, and the ratio of the number of trays in the top is 1 to 10% of the total number of stages, and

[0116] (5) The raw material, an aliphatic monohydric alcohol, is continuously introduced into the continuous multi-stage distillation column from one or more of the second inlets, and the stage is from the uppermost inlet of one or more of the second inlets to the uppermost inlet of one or more of the first inlets, and the ratio of the number of trays in the stage is 40 to 50% of the total number of stages, and

[0117] (6) The bottom is a lower section than the uppermost section among one or more of the second sections, and the ratio of the number of trays in the bottom is 45 to 55% of the total number of sections, and

[0118] (7) For each tray at the bottom, the ratio of the active area calculated in the following formula (i) is 40 to 80%, and the ratio of the open area calculated in the following formula (ii) is 1.0 to 5.0%, and

[0119] Ratio of active area (%) = Active area (㎠) / Tray area (㎠) × 100 ...(i)

[0120] (In Equation (i), the active area refers to the area of ​​the perforated section of the tray deck (the range extending 4 inches further outward from the boundary of the minimum section containing all perforations), and the tray area refers to the area of ​​the tray deck, which includes the active area but excludes the downcomer section.)

[0121] Ratio of open area (%) = Open area (㎠) / Active area (㎠) × 100 ...(ii)

[0122] (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area refers to the same as Equation (i).)

[0123] (8) In each tray of the top and middle sections, the ratio of the active area calculated in the above formula (i) is 40 to 80%, and the ratio of the open area calculated in the above formula (ii) is 1.0 times or more of the ratio of the open area calculated in the above formula (ii) in each tray of the bottom section.

[0124] In addition, regarding the requirements (1) to (8) for the continuous multi-stage distillation column of the present embodiment, they are the same as the requirements (1) to (8) for the manufacturing method of the present embodiment.

[0125] In addition, in the manufacturing method of the present embodiment, at the top, it is preferable that the gas flow rate is 5,000 to 45,000 kg / hour and the liquid flow rate is 1,000 to 15,000 kg / hour.

[0126] In addition, in the manufacturing method of the present embodiment, it is preferable that the gas flow rate is 5,000 to 30,000 kg / hour and the liquid flow rate is 1,000 to 15,000 kg / hour.

[0127] In addition, in the manufacturing method of the present embodiment, at the bottom, it is preferable that the gas flow rate is 5,000 to 20,000 kg / hour and the liquid flow rate is 1,000 to 30,000 kg / hour.

[0128] In addition, in the manufacturing method of the present embodiment, it is preferable that the amount of dialkyl carbonate produced is 4.5 tons or more per hour.

[0129] In addition, in the manufacturing method of the present embodiment, it is preferable that the amount of diol produced is 2.5 tons or more per hour.

[0130] Here, the term “top of the tower or the upper part of the tower near it” used in this embodiment refers to the portion extending downward from the top of the tower to about 0.25 L, and the term “bottom of the tower or the lower part of the tower near it” refers to the portion extending upward from the bottom of the tower to about 0.25 L. In addition, “L” is the same as the definition described above.

[0131] The manufacturing method of the present embodiment is a reactive distillation method that performs not only simple distillation but also a reaction simultaneously, and furthermore achieves a high reaction rate and a high selectivity rate (high yield). To achieve this, it was found that, in addition to the above equations (1) and (2), it is important to set the end of the inlet port of each raw material and the active area and open area of ​​each tray to a specific range. Here, the preferred ranges for each factor are shown below.

[0132] If L(cm) is 1,500 or more, the reaction rate is improved so that the target production volume can be achieved, and if L(cm) is 12,000 or less, equipment costs can be reduced while securing a reaction rate that can achieve the target production volume. The preferred range of L(cm) is 2,000≤L≤10,000, more preferably 2,200≤L≤5,000, and even more preferably 2,500≤L≤5,000.

[0133] In addition, if D(cm) is 120 or more, the target production volume can be achieved, and if D(cm) is 3,000 or less, the equipment cost can be reduced while achieving the target production volume. The preferred range of D(cm) is 150≤D≤2,000, more preferably 180≤D≤1,200, and even more preferably 210≤D≤800.

[0134] The continuous multi-stage distillation column used in this embodiment is preferably a shelf-stage distillation column having n stages of trays having multiple holes as internals. In this embodiment, "internal" refers to a part of the distillation column where actual gas-liquid contact takes place. As such trays, examples include foam trays, perforated plate trays, ripple trays, ballast trays, valve trays, counterflow trays, Uniflux trays, Superflag trays, Maxflag trays, dual flow trays, grid plate trays, turbo grid plate trays, Kittel trays, and high-performance trays such as UFM (manufactured by Sulzer). In this continuous multi-stage distillation column, if there is a stage where no catalyst is present and no reaction substantially takes place (e.g., a stage above the catalyst introduction stage), it is also preferable to make the distillation column with packing material filled in this stage, that is, a multi-stage distillation column having both a tray section and a section filled with packing material. As such packing materials, irregular packing materials such as Raschig rings, Lessing rings, Paul rings, Hummingbirds, Interlock saddles, Dixon packing, McMahon packing, and Helipack, or regular packing materials such as Melapack, Gempack, Technopack, Flexipack, Sulzer packing, Goodroll packing, and Glitchgrid are preferred. In addition, the term "number of stages n" as used in this embodiment refers to the number of trays in the case of trays, and the theoretical number of stages in the case of packing materials. Accordingly, in the case of a multi-stage distillation column having both a tray section and a section filled with packing materials, the number of stages n is the sum of the number of trays and the theoretical number of stages.

[0135] In the manufacturing method of the present embodiment, high reaction rate, high selectivity, and high productivity can be achieved regardless of which of the n-stage trays described above is used; however, a perforated plate tray having a perforated plate section (tray deck section) and a downcomer section is particularly preferred in terms of function and equipment cost. Furthermore, it is preferable that the perforated plate tray has 100 to 1,000 holes per 1 m² of the perforated plate section area. A more preferable number of holes is 120 to 900 per 1 m² of the perforated plate section area, and even more preferably 150 to 800. Additionally, it is preferable that the cross-sectional area per hole of the perforated plate tray is 0.5 to 5 cm². A more preferable cross-sectional area per hole is 0.7 to 4 cm², and even more preferably 0.9 to 3 cm². Furthermore, it is particularly desirable that the perforated plate tray has 100 to 1,000 holes per 1 m² of the perforated plate area and a cross-sectional area of ​​0.5 to 5 cm² per hole. Additionally, the number of holes in the perforated plate area may be the same for all perforated plates, or different, provided that the requirements of (7) and (8) are satisfied.

[0136] FIG. 2 illustrates a conceptual diagram showing an example of a tray structure inside a continuous multi-stage distillation column used in the present embodiment. As shown in FIG. 2, the tray inside the distillation column has a downcomer section (11) and a tray deck section (13), and the section containing holes (14) (the part indicated by a small circle in FIG. 2 represents each hole) within the tray deck section (13) (the range extending 4 inches further outward from the boundary (15) of the minimum section containing all holes) is the active area (12). During distillation in the active area (12), the liquid and vapor actually come into contact, and in the downcomer section (13), the liquid that has foamed on the tray deck section (13) is separated into liquid and vapor, and only the liquid is sent to the lower stage.

[0137] The ratio of the active area in each tray used in this embodiment is calculated using the following formula (i).

[0138] Ratio of active area (%) = Active area (㎠) / Tray area (㎠) × 100 ...(i)

[0139] (In Equation (i), the active area refers to the area of ​​the perforated section of the tray deck (the range extending 4 inches further outward from the boundary of the minimum section containing all perforations), and the tray area refers to the area of ​​the tray deck, which includes the active area but excludes the downcomer section.)

[0140] In addition, the ratio of the open area in each tray used in this embodiment is calculated using the following formula (ii).

[0141] Ratio of open area (%) = Open area (㎠) / Active area (㎠) × 100 ...(ii)

[0142] (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area refers to the same as Equation (i).)

[0143] In addition, for each upper and middle tray used in the present embodiment, the ratio (%) of the active area calculated by the above formula (i) is 40 to 80%, preferably 40 to 70%, more preferably 45 to 65%, and particularly preferably 45 to 55%. In addition, for each lower tray used in the present embodiment, the ratio (%) of the active area calculated by the above formula (i) is 40 to 80%, preferably 40 to 70%, more preferably 45 to 65%, and particularly preferably 45 to 55%. In addition, for each lower tray used in the present embodiment, the ratio (%) of the open area calculated by the above formula (ii) is 1.0 to 5.0%, preferably 1.0 to 4.0%, and more preferably 2.0 to 3.5%. In addition, in each of the upper and middle trays used in the present embodiment, the ratio of the open area (%) calculated in the above formula (ii) is at least 1.0 times the ratio of the open area calculated in the above formula (ii) in each of the lower trays, preferably 1.0 to 6.0 times, more preferably 1.0 to 3.0 times, and even more preferably 1.0 to 1.5 times.

[0144] In each of the upper, middle, and lower trays, by making the ratio of the active area to the open area greater than the lower limit, the differential pressure within the tower is reduced, processing capacity is improved, the reaction proceeds sufficiently, the yield is improved, and production volume is improved. In addition, by making the ratio of the active area to the open area less than the upper limit in each of the upper, middle, and lower trays, the separation of reaction products is sufficiently achieved, the purity of the product is improved, the reaction proceeds sufficiently, the yield is improved, and production volume is improved.

[0145] When carrying out the manufacturing method of the present embodiment, it is preferable to control the gas flow rate and the liquid flow rate at each of the upper, middle, and lower sections.

[0146] In the upper portion used in this embodiment, the gas flow rate (kg / hour) is preferably 5,000 to 45,000 kg / hour, more preferably 10,000 to 25,000 kg / hour, and even more preferably 15,000 to 25,000 kg / hour.

[0147] In the interruption used in the present embodiment, the gas flow rate (kg / hour) is preferably 5,000 to 30,000 kg / hour, more preferably 10,000 to 25,000 kg / hour, and even more preferably 10,000 to 20,000 kg / hour.

[0148] In the lower portion used in this embodiment, the gas flow rate (kg / hour) is preferably 5,000 to 20,000 kg / hour, and more preferably 5,000 to 10,000 kg / hour.

[0149] In the upper portion used in this embodiment, the liquid flow rate (kg / hour) is preferably 1,000 to 15,000 kg / hour, more preferably 3,000 to 10,000 kg / hour, and even more preferably 4,000 to 8,000 kg / hour.

[0150] In the step used in the present embodiment, the liquid flow rate (kg / hour) is preferably 1,000 to 15,000 kg / hour, more preferably 3,000 to 10,000 kg / hour, and even more preferably 3,000 to 8,000 kg / hour.

[0151] In the lower portion used in this embodiment, the liquid flow rate (kg / hour) is preferably 1,000 to 30,000 kg / hour, more preferably 5,000 to 20,000 kg / hour, and even more preferably 5,000 to 15,000 kg / hour.

[0152] If the gas flow rate and liquid flow rate of the upper, middle, and lower sections respectively used in this embodiment are set above the lower limit, the separation of reaction products becomes sufficient, resulting in improved product purity, sufficient reaction progress, improved yield, and increased production volume. Furthermore, if the gas flow rate and liquid flow rate of the upper, middle, and lower sections respectively used in this embodiment are set below the upper limit, the differential pressure within the column is reduced, resulting in improved processing capacity, sufficient reaction progress, improved yield, and increased production volume.

[0153] By adding the above-mentioned conditions to a continuous multi-stage distillation column, the objective of the present invention is achieved more easily.

[0154] When carrying out the manufacturing method of the present embodiment, the raw materials, cyclic carbonates and aliphatic monohydric alcohols, are continuously supplied into a continuous multi-stage distillation column where a catalyst is present, and reaction and distillation are carried out simultaneously within the column, so that the low-boiling point reaction mixture containing the generated dialkyl carbonates is continuously discharged as a gas from the top of the column and the high-boiling point reaction mixture containing diols is continuously discharged as a liquid from the bottom of the column, thereby continuously producing dialkyl carbonates and diols.

[0155] The reaction time of the ester exchange reaction carried out in the manufacturing method of the present embodiment is thought to correspond to the average residence time of the reaction liquid in a continuous multi-stage distillation column, but this varies depending on the shape or number of stages of the internal of the distillation column, the amount of raw material supplied, the type or amount of catalyst, reaction conditions, etc., but is preferably 0.1 to 20 hours, more preferably 0.5 to 15 hours, and even more preferably 1 to 10 hours.

[0156] The reaction temperature of the ester exchange reaction carried out in the manufacturing method of the present embodiment varies depending on the type of raw material compound used and the type and amount of catalyst, but is preferably 30 to 300°C. While it is desirable to increase the reaction temperature to increase the reaction rate, side reactions are also more likely to occur if the reaction temperature is high. Therefore, a more preferable reaction temperature is in the range of 40 to 250°C, more preferably 50 to 200°C, and particularly preferably 60 to 150°C. In the manufacturing method of the present embodiment, reaction distillation can be carried out with the column bottom temperature preferably 150°C or lower, more preferably 130°C or lower, even more preferably 110°C or lower, and particularly more preferably 100°C or lower. One of the excellent features of the present invention is that a high reaction rate, high selectivity, and high productivity can be achieved even at such a low column bottom temperature. In addition, the reaction pressure of the transesterification reaction carried out in the manufacturing method of the present embodiment varies depending on the type and composition of the raw material compound used, the reaction temperature, etc., but may be reduced pressure, atmospheric pressure, or pressurized, and preferably 1 Pa to 2 × 10⁻⁶ 7 It is Pa, and more preferably 10 3 Pa~10 7 Pa, and more preferably 10 4 ~5×10 6 It is Pa.

[0157] The material constituting the continuous multi-stage distillation column used in this embodiment is not particularly limited, but, for example, metal materials such as carbon steel and stainless steel can be used, and stainless steel is preferred in terms of the quality of the dialkyl carbonates and diols produced.

[0158] Examples

[0159] The present invention will be explained more specifically below by way of examples, but the present invention is not limited to the following examples.

[0160] [Example 1]

[0161] Continuous multi-stage distillation column

[0162] A continuous multi-stage distillation column (shelf-stage distillation column) was used, as shown in FIG. 1, with a column length L: 3300 cm, column inner diameter D: 300 cm, L / D: 11, number of stages n: 60, ratio of column inner diameter D to gas outlet inner diameter d1 (D / d1): 7.5, and ratio of column inner diameter D to liquid outlet inner diameter d2 (D / d2): 12. The trays of this distillation column were perforated plate trays having multiple holes, and the cross-sectional area per hole in the perforated plate section was approximately 1.3 cm². In addition, the internal (tray) structure of this distillation column varied depending on the installation location and consisted of three types of trays: upper, middle, and lower. The upper section was the stage above the inlet of the annular carbonate (ethylene carbonate) (inlet formed at the 5th stage from the top of the distillation column (3-a)). The number of trays in the upper section was 5, which accounted for 8.3% of the total number of stages, 60. Additionally, the ratio of the active area in each tray of the upper section was 45%, and the ratio of the open area was 4.5%. Additionally, the middle section consisted of the section with the introduction port for cyclic carbonate (ethylene carbonate) (introduction port formed at the 5th stage from the top of the distillation column (3-a)) and the stage below it, and the section with the introduction port for aliphatic monohydric alcohol (methanol) (introduction ports formed at the 30th stage from the top of the distillation column (3-b and 3-c)) and the stage above it. The number of trays in the middle section was 24, which accounted for 40% of the total number of stages, 60. Additionally, the ratio of the active area in each tray of the middle section was 45%, and the ratio of the open area was 3.5%. In addition, the bottom was a stage lower than the stage of the inlet for the aliphatic monohydric alcohol (methanol) (inlet formed at the 30th stage from the top of the distillation column (3-b and 3-c)). The number of trays in the bottom was 31, which was 51.7% of the total number of stages, 60. In addition, the ratio of the active area of ​​each tray in the bottom was 45%, and the ratio of the open area was 3.0%.

[0163] Reactive distillation

[0164] In the continuous multi-stage distillation column shown in FIG. 1, liquid ethylene carbonate is continuously introduced into the distillation column from an inlet (3-a) formed at the 5th stage from the top of the distillation column at a flow rate of 4.7 tons / hour. Gaseous methanol (containing 8.8 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-b) formed at the 30th stage from the top of the distillation column at a flow rate of 4.622 tons / hour, and liquid methanol (containing 6.5 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-c) formed at the 30th stage from the top of the distillation column at a flow rate of 10.695 tons / hour.

[0165] The catalyst consisted of a mixture of an alkali metal and ethylene glycol, and the mass ratio of the alkali metal to the ethylene glycol (alkali metal / ethylene glycol) in the catalyst was in the range of 0.2 to 0.3. The catalyst was a homogeneous catalyst synthesized by adding 4.8 tons of ethylene glycol to 2.5 tons of alkali metal (potassium), heating to approximately 130°C, and heat-treating at approximately 1300 Pa for approximately 3 hours to form a homogeneous solution. This homogeneous catalyst solution was continuously introduced into the distillation column from an inlet (3-e) formed at the 54th stage from the bottom of the distillation column (catalyst concentration (converted to alkali metal concentration): 1.0 mass% relative to the feed ethylene carbonate). The temperature at the bottom of the column was 98°C, and the pressure at the top of the column was approximately 1.118 × 10⁻⁶ 5 Continuous reaction distillation was carried out under conditions of Pa and a reflux ratio of 0.52.

[0166] When reactive distillation was carried out, the gas flow rate at the top of the tower was in the range of 19,600–23,000 kg / hour and the liquid flow rate was in the range of 6,000–7,700 kg / hour, the gas flow rate at the middle of the tower was in the range of 9,250–16,000 kg / hour and the liquid flow rate was in the range of 5,800–6,500 kg / hour, and the gas flow rate at the bottom of the tower was in the range of 5,280–10,000 kg / hour and the liquid flow rate was in the range of 7,980–14,900 kg / hour.

[0167] Stable normal operation was achieved after 24 hours. The low-boiling point reaction mixture that exited in gaseous form from the gas outlet (1) at the top of the tower was cooled by a heat exchanger and turned into liquid. Among the liquid low-boiling point reaction mixture that exited continuously from the distillation tower at a rate of 15.246 tons / hour, the proportion of dimethyl carbonate was 5.283 tons / hour and the proportion of methanol was 8.429 tons / hour. Among the liquid that exited continuously at a rate of 4.883 tons / hour from the liquid outlet (2) at the bottom of the tower, the proportion of ethylene glycol was 3.027 tons / hour, the proportion of methanol was 1.303 tons / hour, and the proportion of unreacted ethylene carbonate was 7.6 kg / hour. The actual hourly production of dimethyl carbonate, excluding the dimethyl carbonate contained in the raw material, was 4.651 tons, and the actual hourly production of ethylene glycol, excluding the ethylene glycol contained in the catalyst solution, was 2.955 tons. The reaction rate of ethylene carbonate was 99.7%, the selectivity of dimethyl carbonate was 99.99% or higher, and the selectivity of ethylene glycol was 99.99% or higher.

[0168] Continuous operation was performed for a long period under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours of continuous operation, the actual hourly production of dimethyl carbonate is 4.661 tons, 4.682 tons, 4.661 tons, 4.661 tons, and 4.692 tons, respectively; the actual hourly production of ethylene glycol is 2.982 tons, 2.955 tons, 2.9222 tons, 2.952 tons, and 2.996 tons, respectively; the reaction rates of ethylene carbonate are 99.89%, 99.90%, 99.90%, 99.88%, and 99.92%, respectively; and the selectivity of dimethyl carbonate is 99.99% or more, 99.99% or more, 99.99% or more, and 99.99% or more, respectively. and 99.99% or more, and the selectivity of ethylene glycol was 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more, and 99.99% or more.

[0169] [Example 2]

[0170] Continuous multi-stage distillation column

[0171] Reactive distillation was performed using the same continuous multi-stage distillation column as in Example 1, with the tray structure modified as follows. In each upper stage tray, the ratio of the active region was 60% and the ratio of the open region was 5.0%. In each middle stage tray, the ratio of the active region was 60% and the ratio of the open region was 4.0%. In each lower stage tray, the ratio of the active region was 45% and the ratio of the open region was 3.5%.

[0172] Reactive distillation

[0173] Continuous reaction distillation was carried out under the same conditions as Example 1, except for the conditions described below.

[0174] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) formed at the 54th stage from the bottom of the distillation column (catalyst concentration (converted to alkali metal concentration): 0.5 mass% relative to the feed ethylene carbonate). The temperature at the bottom of the column was 98°C, and the pressure at the top of the column was approximately 1.118 × 10⁻⁶. 5 Reactive distillation was carried out continuously under conditions of Pa and a reflux ratio of 0.6.

[0175] When reactive distillation was carried out, the gas flow rate at the top of the tower was in the range of 21,200–24,500 kg / hour and the liquid flow rate was in the range of 4,730–6,250 kg / hour, the gas flow rate at the middle was in the range of 10,040–19,200 kg / hour and the liquid flow rate was in the range of 4,630–6,000 kg / hour, and the gas flow rate at the bottom was in the range of 6,170–9,490 kg / hour and the liquid flow rate was in the range of 7,200–14,100 kg / hour.

[0176] Stable normal operation was achieved after 24 hours. The low-boiling point reaction mixture that exited in gaseous form from the gas outlet (1) at the top of the tower was cooled by a heat exchanger and turned into liquid. Among the liquid low-boiling point reaction mixture that exited continuously from the distillation tower at a rate of 15.246 tons / hour, the proportion of dimethyl carbonate was 5.577 tons / hour and the proportion of methanol was 8.898 tons / hour. Among the liquid that exited continuously at a rate of 4.639 tons / hour from the liquid outlet (2) at the bottom of the tower, the proportion of ethylene glycol was 3.200 tons / hour, the proportion of methanol was 1.376 tons / hour, and the proportion of unreacted ethylene carbonate was 5.6 kg / hour. The actual hourly production of dimethyl carbonate, excluding the dimethyl carbonate included in the raw material, was 4.920 tons, and the actual hourly production of ethylene glycol, excluding the ethylene glycol included in the catalyst solution, was 3.119 tons. The reaction rate of ethylene carbonate was 99.88%, the selectivity of dimethyl carbonate was 99.99% or higher, and the selectivity of ethylene glycol was 99.99% or higher.

[0177] Continuous operation was performed for a long period under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours of continuous operation, the actual hourly production of dimethyl carbonate is 4.630 tons, 4.828 tons, 4.639 tons, 4.635 tons, and 4.728 tons, respectively; the actual hourly production of ethylene glycol is 3.222 tons, 3.283 tons, 3.265 tons, 3.226 tons, and 3.232 tons, respectively; the reaction rate of ethylene carbonate is 99.99%, 99.99%, 99.99%, 99.99%, and 99.99%, respectively; and the selectivity of dimethyl carbonate is 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more, and 99.99% or more, respectively. The selectivity of ethylene glycol was 99.99% or higher, and the selectivity of ethylene glycol was 99.99% or higher, 99.99% or higher, 99.99% or higher, and 99.99% or higher.

[0178] [Example 3]

[0179] Continuous multi-stage distillation column

[0180] A continuous multi-stage distillation column identical to that of Example 1 was used, the tray structure was set to be identical to that of Example 1 as follows, and reactive distillation was performed by changing the amount of raw material introduced into the distillation column.

[0181] In each top row tray, the ratio of the active area was 45% and the ratio of the open area was 4.5%. In addition, in each middle row tray, the ratio of the active area was 45% and the ratio of the open area was 3.5%. In addition, in each bottom row tray, the ratio of the active area was 45% and the ratio of the open area was 3.0%.

[0182] In the continuous multi-stage distillation column shown in FIG. 1, liquid ethylene carbonate is continuously introduced into the distillation column from an inlet (3-a) formed at the 5th stage from the top of the distillation column at a flow rate of 8.68 tons / hour. Gaseous methanol (containing 8.8 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-b) formed at the 30th stage from the top of the distillation column at a flow rate of 8.53 tons / hour, and liquid methanol (containing 6.5 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-c) formed at the 30th stage from the top of the distillation column at a flow rate of 19.74 tons / hour.

[0183] Reactive distillation

[0184] Continuous reaction distillation was carried out under the same conditions as Example 1, except for the conditions described below.

[0185] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) formed at the 54th stage from the bottom of the distillation column (catalyst concentration (converted to alkali metal concentration): 0.6 mass% with respect to feed ethylene carbonate). The temperature at the bottom of the column was 98°C, and the pressure at the top of the column was approximately 1.118 × 10⁻⁶. 5 Reactive distillation was carried out continuously under conditions of Pa and a reflux ratio of 0.45.

[0186] When reactive distillation was carried out, the gas flow rate at the top of the tower was in the range of 36,260 to 42,550 kg / hour and the liquid flow rate was in the range of 11,100 to 14,250 kg / hour, the gas flow rate at the middle was in the range of 17,110 to 29,600 kg / hour and the liquid flow rate was in the range of 10,730 to 12,030 kg / hour, and the gas flow rate at the bottom was in the range of 9,770 to 18,500 kg / hour and the liquid flow rate was in the range of 14,760 to 27,570 kg / hour.

[0187] Stable normal operation was achieved after 24 hours. The low-boiling point reaction mixture that exited in gaseous form from the gas outlet (1) at the top of the tower was cooled by a heat exchanger and turned into liquid. Among the liquid low-boiling point reaction mixture that exited continuously from the distillation tower at a rate of 28.205 tons / hour, the proportion of dimethyl carbonate was 9.774 tons / hour and the proportion of methanol was 15.594 tons / hour. Among the liquid that exited continuously at a rate of 9.034 tons / hour from the liquid outlet (2) at the bottom of the tower, the proportion of ethylene glycol was 5.600 tons / hour, the proportion of methanol was 2.411 tons / hour, and the proportion of unreacted ethylene carbonate was 14.06 kg / hour. The actual hourly production of dimethyl carbonate, excluding the dimethyl carbonate included in the raw material, was 8.604 tons, and the actual hourly production of ethylene glycol, excluding the ethylene glycol included in the catalyst solution, was 5.467 tons. The reaction rate of ethylene carbonate was 99.88%, the selectivity of dimethyl carbonate was 99.99% or higher, and the selectivity of ethylene glycol was 99.99% or higher.

[0188] Continuous operation was performed for a long period under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours of continuous operation, the actual hourly production of dimethyl carbonate is 8.604 tons, 8.604 tons, 8.604 tons, 8.604 tons, and 8.604 tons, respectively; the actual hourly production of ethylene glycol is 5.467 tons, 5.467 tons, 5.467 tons, 5.467 tons, and 5.467 tons, respectively; the reaction rate of ethylene carbonate is 99.99%, 99.99%, 99.99%, 99.99%, and 99.99%, respectively; and the selectivity of dimethyl carbonate is 99.99% or more, 99.99% or more, 99.99% or more, 99.99% or more, and 99.99% or more, respectively. The selectivity of ethylene glycol was 99.99% or higher, and the selectivity of ethylene glycol was 99.99% or higher, 99.99% or higher, 99.99% or higher, and 99.99% or higher.

[0189] [Comparative Example 1]

[0190] Continuous multi-stage distillation column

[0191] Reactive distillation was performed using the same continuous multi-stage distillation column as in Example 1, with the tray structure modified as follows. In each upper stage tray, the ratio of the active region was 38% and the ratio of the open region was 4.5%. In addition, in each middle stage tray, the ratio of the active region was 38% and the ratio of the open region was 4.5%. In addition, in each lower stage tray, the ratio of the active region was 38% and the ratio of the open region was 4.8%.

[0192] Reactive distillation

[0193] Continuous reaction distillation was carried out under the same conditions as Example 1, except for the conditions described below.

[0194] In the continuous multi-stage distillation column shown in FIG. 1, liquid ethylene carbonate is continuously introduced into the distillation column from an inlet (3-a) formed at the 5th stage from the top of the distillation column at a flow rate of 7.546 tons / hour. Gaseous methanol (containing 8.8 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-b) formed at the 30th stage from the top of the distillation column at a flow rate of 7.742 tons / hour, and liquid methanol (containing 6.5 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-c) formed at the 30th stage from the top of the distillation column at a flow rate of 17.282 tons / hour.

[0195] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) formed at the 54th stage from the bottom of the distillation column (catalyst concentration (converted to alkali metal concentration): 0.6 mass% with respect to feed ethylene carbonate).

[0196] The temperature at the bottom of the tower is 98°C, and the pressure at the top of the tower is approximately 1.118 × 10⁻⁶ 5 Reactive distillation was carried out continuously under conditions of Pa and a reflux ratio of 0.45.

[0197] When reactive distillation was carried out, the gas flow rate at the top of the column was in the range of 31523–36991 kg / hour and the liquid flow rate was in the range of 9906–12384 kg / hour, the gas flow rate at the middle was in the range of 15272–25733 kg / hour and the liquid flow rate was in the range of 9575–10454 kg / hour, and the gas flow rate at the bottom was in the range of 8717–16083 kg / hour and the liquid flow rate was in the range of 13174–23964 kg / hour.

[0198] Stable normal operation was achieved after 24 hours. The low-boiling point reaction mixture that exited in gaseous form from the gas outlet (1) at the top of the tower was cooled by a heat exchanger and turned into liquid. Among the liquid low-boiling point reaction mixture that exited continuously from the distillation tower at a rate of 24.642 tons / hour, the proportion of dimethyl carbonate was 4.109 tons / hour and the proportion of methanol was 15.115 tons / hour. Among the liquid that exited continuously at a rate of 7.804 tons / hour from the liquid outlet (2) at the bottom of the tower, the proportion of ethylene glycol was 5.436 tons / hour, the proportion of methanol was 2.34 tons / hour, and the proportion of unreacted ethylene carbonate was 14.122 kg / hour. The actual hourly production of dimethyl carbonate, excluding the dimethyl carbonate included in the raw material, was 7.708 tons, and the actual hourly production of ethylene glycol, excluding the ethylene glycol included in the catalyst solution, was 5.310 tons. The reaction rate of ethylene carbonate was 99.7%, the selectivity of dimethyl carbonate was 99.99% or higher, and the selectivity of ethylene glycol was 99.99% or higher.

[0199] Continuous operation was performed for a long period under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours of continuous operation, the actual hourly production of dimethyl carbonate is 7.708 tons, 7.708 tons, 7.706 tons, 7.706 tons, and 7.708 tons, respectively; the actual hourly production of ethylene glycol is 5.310 tons, 5.312 tons, 5.310 tons, 5.310 tons, and 5.310 tons, respectively; the reaction rates of ethylene carbonate are 99.7%, 99.7%, 99.7%, 99.7%, and 99.7%, respectively; and the selectivity of dimethyl carbonate is 99.99%, 99.99%, 99.99%, 99.99%, and 99.99%, respectively. The selectivity of ethylene glycol was 99.99%, 99.99%, 99.99%, 99.99%, and 99.99%, in that order.

[0200] [Comparative Example 2]

[0201] Continuous multi-stage distillation column

[0202] Continuous reaction distillation was carried out under the same conditions as in Example 1, except for the conditions described below. An amount of raw material equal to that of Example 3 was continuously introduced into the distillation column.

[0203] In the tray structure of the continuous multi-stage distillation column, the ratio of the active area in each upper stage tray was 82% and the ratio of the open area was 4.9%. In addition, in each middle stage tray, the ratio of the active area was 82% and the ratio of the open area was 4.9%. In addition, in each lower stage tray, the ratio of the active area was 85% and the ratio of the open area was 3.3%.

[0204] In the continuous multi-stage distillation column shown in FIG. 1, liquid ethylene carbonate is continuously introduced into the distillation column from an inlet (3-a) formed at the 5th stage from the top of the distillation column at a flow rate of 8.68 tons / hour. Gaseous methanol (containing 8.8 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-b) formed at the 30th stage from the top of the distillation column at a flow rate of 8.53 tons / hour, and liquid methanol (containing 6.5 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-c) formed at the 30th stage from the top of the distillation column at a flow rate of 19.74 tons / hour.

[0205] Reactive distillation

[0206] Continuous reaction distillation was carried out under the same conditions as in Example 3.

[0207] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) formed at the 54th stage from the bottom of the distillation column (catalyst concentration (converted to alkali metal concentration): 0.6 mass% with respect to feed ethylene carbonate). The temperature at the bottom of the column was 98°C, and the pressure at the top of the column was approximately 1.118 × 10⁻⁶.5 Reactive distillation was carried out continuously under conditions of Pa and a reflux ratio of 0.45.

[0208] When reactive distillation was carried out, the gas flow rate at the top of the tower was in the range of 33,250 to 40,200 kg / hour and the liquid flow rate was in the range of 12,520 to 40,200 kg / hour, the gas flow rate at the middle was in the range of 15,420 to 25,200 kg / hour and the liquid flow rate was in the range of 12,320 to 14,250 kg / hour, and the gas flow rate at the bottom was in the range of 8,270 to 14,200 kg / hour and the liquid flow rate was in the range of 13,750 to 24,450 kg / hour.

[0209] Stable normal operation was achieved after 24 hours. The low-boiling point reaction mixture that exited in gaseous form from the gas outlet (1) at the top of the tower was cooled by a heat exchanger and turned into liquid. Among the liquid low-boiling point reaction mixture that exited continuously from the distillation tower at a rate of 28.036 tons / hour, the proportion of dimethyl carbonate was 9.715 tons / hour and the proportion of methanol was 15.500 tons / hour. Among the liquid that exited continuously at a rate of 8.979 tons / hour from the liquid outlet (2) at the bottom of the tower, the proportion of ethylene glycol was 5.634 tons / hour, the proportion of methanol was 2.396 tons / hour, and the proportion of unreacted ethylene carbonate was 14.153 kg / hour. The actual hourly production of dimethyl carbonate, excluding the dimethyl carbonate included in the raw material, was 8.543 tons, and the actual hourly production of ethylene glycol, excluding the ethylene glycol included in the catalyst solution, was 5.431 tons. The reaction rate of ethylene carbonate was 99.33%, the selectivity of dimethyl carbonate was 99.33%, and the selectivity of ethylene glycol was 99.33%.

[0210] Continuous operation was performed for a long period under these conditions. After 500 hours, 1000 hours, and 2000 hours of this continuous operation, the actual hourly production of dimethyl carbonate was 8.547 tons, 8.547 tons, and 8.546 tons, respectively, and the actual hourly production of ethylene glycol was 5.431 tons, 5.430 tons, and 5.431 tons, respectively, and the reaction rate of ethylene carbonate was 99.33%, 99.33%, and 99.32%, respectively, and the selectivity of dimethyl carbonate was 99.43%, 99.43%, and 99.53%, respectively, and the selectivity of ethylene glycol was 99.43%, 99.43%, and 99.43%, respectively.

[0211] [Comparative Example 3]

[0212] Continuous multi-stage distillation column

[0213] Continuous reaction distillation was carried out under the same conditions as Example 1, except for the conditions described below. An amount of raw material equal to that of Comparative Example 1 was continuously introduced into the distillation column.

[0214] In the tray structure of the continuous multi-stage distillation column, the ratio of the active area in each upper stage tray was 82% and the ratio of the open area was 4.9%. In addition, in each middle stage tray, the ratio of the active area was 82% and the ratio of the open area was 4.9%. In addition, in each lower stage tray, the ratio of the active area was 85% and the ratio of the open area was 3.3%.

[0215] In the continuous multi-stage distillation column shown in FIG. 1, liquid ethylene carbonate is continuously introduced into the distillation column from an inlet (3-a) formed at the 5th stage from the top of the distillation column at a flow rate of 7.546 tons / hour. Gaseous methanol (containing 8.8 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-b) formed at the 30th stage from the top of the distillation column at a flow rate of 7.742 tons / hour, and liquid methanol (containing 6.5 mass% of dimethyl carbonate) is continuously introduced into the distillation column from an inlet (3-c) formed at the 30th stage from the top of the distillation column at a flow rate of 17.282 tons / hour.

[0216] Reactive distillation

[0217] Continuous reaction distillation was carried out under the same conditions as Comparative Example 1.

[0218] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) formed at the 54th stage from the bottom of the distillation column (catalyst concentration (converted to alkali metal concentration): 0.6 mass% with respect to feed ethylene carbonate). The temperature at the bottom of the column was 98°C, and the pressure at the top of the column was approximately 1.118 × 10⁻⁶. 5 Reactive distillation was carried out continuously under conditions of Pa and a reflux ratio of 0.45.

[0219] When reactive distillation was carried out, the gas flow rate at the top of the tower was in the range of 31544–36975 kg / hour and the liquid flow rate was in the range of 9912–12348 kg / hour, the gas flow rate at the middle was in the range of 15274–25733 kg / hour and the liquid flow rate was in the range of 9572–10448 kg / hour, and the gas flow rate at the bottom was in the range of 8720–16078 kg / hour and the liquid flow rate was in the range of 13180–23928 kg / hour.

[0220] Stable normal operation was achieved after 24 hours. The low-boiling point reaction mixture that exited in gaseous form from the gas outlet (1) at the top of the tower was cooled by a heat exchanger and turned into liquid. Among the liquid low-boiling point reaction mixture that exited continuously from the distillation tower at a rate of 26.669 tons / hour, the proportion of dimethyl carbonate was 4.113 tons / hour and the proportion of methanol was 15.130 tons / hour. Among the liquid that exited continuously at a rate of 7.796 tons / hour from the liquid outlet (2) at the bottom of the tower, the proportion of ethylene glycol was 5.441 tons / hour, the proportion of methanol was 2.338 tons / hour, and the proportion of unreacted ethylene carbonate was 14.082 kg / hour. The actual hourly production of dimethyl carbonate, excluding the dimethyl carbonate included in the raw material, was 7.716 tons, and the actual hourly production of ethylene glycol, excluding the ethylene glycol included in the catalyst solution, was 5.315 tons. The reaction rate of ethylene carbonate was 99.80%, the selectivity of dimethyl carbonate was 99.89%, and the selectivity of ethylene glycol was 99.90%.

[0221] Continuous operation was performed for a long period under these conditions. After 500 hours, 1000 hours, and 2000 hours of this continuous operation, the actual hourly production of dimethyl carbonate was 7.716 tons, 7.716 tons, and 7.716 tons, respectively, and the actual hourly production of ethylene glycol was 5.315 tons, 5.315 tons, and 5.315 tons, respectively, and the reaction rate of ethylene carbonate was 99.80%, 99.80%, and 99.80%, respectively, and the selectivity of dimethyl carbonate was 99.90%, 99.90%, and 99.90%, respectively, and the selectivity of ethylene glycol was 99.90%, 99.89%, and 99.90%, respectively.

[0222] This application is based on Japanese patent application filed on January 8, 2021 (JP No. 2021-002028), the contents of which are incorporated herein by reference. Industrial applicability

[0223] According to the present invention, from a cyclic carbonate and an aliphatic monohydric alcohol, the dialkyl carbonate and diols can each be produced with a high selectivity of 97% or more, preferably 99% or more, more preferably 99.99% or more, with the dialkyl carbonate being produced at an industrial scale of 4.5 tons or more per hour, preferably 5 tons or more per hour, more preferably 5.2 tons or more per hour, and the diols being produced at 2.5 tons or more per hour, preferably 3.0 tons or more per hour, more preferably 3.2 tons or more per hour, for a long period of 1,000 hours or more, preferably 3,000 hours or more, more preferably 5,000 hours or more, with a high selectivity of 97% or more, preferably 99% or more, more preferably 99.99% or more, and with a high yield of 1,000 hours or more, preferably 3,000 hours or more, more preferably 5,000 hours or more, and thus have industrial applicability. In addition, the upper limit of the production volume of the dialkyl carbonate is not particularly limited, but for example, 12 tons or less per hour, and the upper limit of the production volume of the diols is not particularly limited, but for example, 8 tons or less per hour. Explanation of the symbols

[0224] 1: Gas outlet, 2: Liquid outlet, 3-a to 3-e: Inlet, 4-a to 4-b: Inlet, 5: End plate section, 6: Internal, 7: Body section, 10: Continuous multi-stage distillation column, L: Body section length (cm), D: Body section inner diameter (cm), d1: Inner diameter of gas outlet (cm), d2: Inner diameter of liquid outlet (cm), 11: Downcomer section, 12: Active area, 13: Tray deck section, 14: One of the holes (the part marked with a small circle is the hole, and the total area of ​​the holes is the open area), 15: Boundary of the minimum area containing all holes.

Claims

Claim 1 In a method of reactive distillation in which cyclic carbonates and aliphatic monohydric alcohols are used as raw materials, the raw materials are continuously supplied into a continuous multi-stage distillation column where a homogeneous catalyst is present, and reaction and distillation are performed simultaneously within the column, and a low-boiling point reaction mixture containing dialkyl carbonates is continuously discharged in a gaseous state from the top of the column and a high-boiling point reaction mixture containing diols is continuously discharged in a liquid state from the bottom of the column, wherein the cyclic carbonate is ethylene carbonate and the aliphatic monohydric alcohol is methanol, and (a) the continuous multi-stage distillation column is a shelf-type distillation column having a cylindrical body portion with length L (cm) and inner diameter D (cm) and a structure having an internal, wherein the internal is a tray having a plurality of holes, a gas outlet at the top of the column or near the top of the column, a liquid outlet at the bottom of the column or near the bottom of the column, one or more first inlets located below the gas outlet and at the top or middle of the column or both, and the liquid (1) The length L (cm) of the column satisfies Equation (1), where 1,500 ≤ L ≤ 12,000 Equation (1)(2) The inner diameter D (cm) of the column satisfies Equation (2), where 120 ≤ D ≤ 3,000 Equation (2)(3) The internal is composed of three types of trays: upper, middle, and lower, (4) A cyclic carbonate, which is a raw material, is continuously introduced into the continuous multi-stage distillation column from one or more of the first inlets, the upper stage is a stage above the uppermost inlet among the one or more first inlets, and the ratio of the number of trays in the upper stage is 1 to 10% of the total number of stages, (5) An aliphatic monohydric alcohol, which is a raw material, is continuously introduced into the continuous multi-stage distillation column from one or more of the second inlets, and(6) The middle section is a section from the uppermost inlet of one or more of the second inlets to the uppermost inlet of one or more of the first inlets, and the ratio of the number of trays in the middle section is 40 to 50% of the total number of sections, and (7) the bottom section is a section lower than the uppermost inlet of one or more of the second inlets, and the ratio of the number of trays in the bottom section is 45 to 55% of the total number of sections, and (7) for each tray in the bottom section, the ratio of the active area calculated by the following formula (i) is 45 to 65%, and the ratio of the open area calculated by the following formula (ii) is 1.0 to 5.0%, and the ratio of the active area (%) = active area area (㎠) / tray area (㎠) × 100 ...(i) (wherein in formula (i), the active area area is the area of ​​the section with holes in the tray deck part (the range from the boundary of the minimum area containing all holes to 4 inches further outward), and the tray area is the area of ​​the tray deck part, including the active area area, and the downcomer (It is an area that does not include the part.) Ratio of open area (%) = Open area (cm²) / Active area (cm²) × 100 ...(ii) (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area refers to the same as Equation (i).) (8) In each tray of the upper and middle sections, the ratio of the active area calculated in Equation (i) is 45 to 65%, and the ratio of the open area calculated in Equation (ii) is at least 1.0 times the ratio of the open area calculated in Equation (ii) in each tray of the lower section, and (9) the homogeneous catalyst is composed of a mixture of alkali metal and ethylene glycol, and in the homogeneous catalyst, the mass ratio of alkali metal and ethylene glycol (alkali metal / ethylene glycol) is 0.05 to 0.5, and the catalyst concentration (converted to alkali metal concentration) is 0.05 to 2.0 mass% with respect to the cyclic carbonate supplied to the distillation column, and the homogeneous catalyst A method for industrially manufacturing dialkyl carbonates and diols, which are mixtures of potassium and ethylene glycol. Claim 2 A method according to claim 1, wherein at the top, the gas flow rate is 5,000 to 45,000 kg / hour and the liquid flow rate is 1,000 to 15,000 kg / hour; at the middle, the gas flow rate is 5,000 to 30,000 kg / hour and the liquid flow rate is 1,000 to 15,000 kg / hour; and at the bottom, the gas flow rate is 5,000 to 20,000 kg / hour and the liquid flow rate is 1,000 to 30,000 kg / hour. Claim 3 A method according to claim 1 or 2, wherein the amount of dialkyl carbonate produced is 4.5 tons or more per hour. Claim 4 A method according to claim 1 or 2, wherein the amount of diols produced is 2.5 tons or more per hour. Claim 5 A continuous multi-stage distillation column for performing an ester exchange reaction and distillation of a cyclic carbonate and an aliphatic monohydric alcohol, wherein the cyclic carbonate is ethylene carbonate and the aliphatic monohydric alcohol is methanol, and (a) a cylindrical body portion having a length L (cm) and an inner diameter D (cm), a tray having a plurality of holes arranged internally within the body portion, a gas outlet at the top of the column or near the top of the column, a liquid outlet at the bottom of the column or near the bottom of the column, one or more first inlets located below the gas outlet and at the top or middle of the column or both, and one or more second inlets located above the liquid outlet and at the middle or bottom of the column or both, and (1) the length L (cm) of the column satisfies Equation (1), where 1,500 ≤ L ≤ 12,000 Equation (1)(2) the inner diameter D (cm) of the column satisfies Equation (2), where 120 ≤ D ≤ 3,000 Equation (2)(3) The above internal consists of three types of trays: upper, middle, and lower; (4) a cyclic carbonate, which is the raw material, is continuously introduced into the continuous multi-stage distillation column from one or more of the first inlets, the upper section is the section above the uppermost inlet among one or more of the first inlets, and the ratio of the number of trays in the upper section is 1 to 10% of the total number of stages; (5) an aliphatic monohydric alcohol, which is the raw material, is continuously introduced into the continuous multi-stage distillation column from one or more of the second inlets, the middle section is the section from the uppermost inlet among one or more of the second inlets to the uppermost inlet among one or more of the first inlets, and the ratio of the number of trays in the middle section is 40 to 50% of the total number of stages; (6) the lower section is the section below the uppermost inlet among one or more of the second inlets, and the ratio of the number of trays in the lower section is 45 to 55% of the total number of stages; (7) in each tray of the lower section, the ratio of the active region calculated by the following formula (i) It is 45–65%, and the ratio of the open area calculated in the following formula (ii) is 1.0–5.0%, and the ratio of the active area (%) = Active area (cm²) / Tray area (cm²) × 100 ... (i) (In Equation (i), the active area refers to the area of ​​the section with holes in the tray deck part (the range extending 4 inches further outward from the boundary of the minimum area containing all holes), and the tray area refers to the area of ​​the tray deck part, which includes the active area but excludes the downcomer part.) The ratio of the open area (%) = Open area (cm²) / Active area (cm²) × 100 ... (ii) (In Equation (ii), the open area refers to the total area of ​​all holes in the active area, and the active area is synonymous with Equation (i).) (8) For each tray of the upper and middle sections, the ratio of the active area calculated in Equation (i) is 45 to 65%, and the ratio of the open area calculated in Equation (ii) is the ratio of the open area calculated in Equation (ii) for each tray of the lower section A continuous multi-stage distillation column with a ratio of 1.0 or more.

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