Method for industrial production of dialkyl carbonates and diols

Abstract

The present invention aims to provide a specific method for industrially producing dialkyl carbonates and diols using cyclic carbonates and aliphatic monohydric alcohols as raw materials with high productivity, long-term stability, high selectivity, and high yield. A method for industrially producing dialkyl carbonates and diols, wherein specific requirements are met when continuously producing dialkyl carbonates and diols by a reactive distillation method in which a cyclic carbonate and an aliphatic monohydric alcohol are continuously supplied to a continuous multi-stage distillation column in the presence of a homogeneous catalyst, the reaction and distillation proceed simultaneously within the column, a low-boiling-point reaction mixture containing the produced dialkyl carbonate is continuously withdrawn from the upper portion of the column in a gaseous state, and a high-boiling-point reaction mixture containing the diols is continuously withdrawn from the lower portion of the column in a liquid state.

Description

Technical Field

[0001] The present invention relates to a process for the industrial production of dialkyl carbonates and diols. Background Art

[0002] As a method for industrially producing dialkyl carbonates and diols, for example, Patent Document 1 proposes a method and apparatus. By using a reactive distillation method in which cyclic carbonates and aliphatic monohydric alcohols are used as raw materials, the raw materials are continuously fed into a continuous multi-stage distillation column in the presence of a homogeneous catalyst, and reaction and distillation are simultaneously carried out in the column, dialkyl carbonates and diols are produced industrially in large quantities (e.g., more than 2 tons of dialkyl carbonate per hour, more than 1.3 tons of diols per hour). The method and apparatus can stably produce dialkyl carbonates and diols at high yields over a long period (e.g., more than 5,000 hours) with high selectivity and high productivity.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2007 / 069514 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, the method and apparatus described in Patent Document 1 may have insufficient productivity of dialkyl carbonate and diols relative to the scale of the apparatus.

[0008] Therefore, the problem to be solved by the present invention is to provide a specific method for industrially mass-producing dialkyl carbonates and diols by a reactive distillation method in which a cyclic carbonate and an aliphatic monohydric alcohol are used as raw materials, the raw materials are continuously supplied to a continuous multi-stage distillation column in the presence of a homogeneous catalyst, and reaction and distillation are simultaneously carried out in the column. The method can stably produce dialkyl carbonates and diols at a higher productivity (for example, 4.5 tons or more of dialkyl carbonate per hour, 2.7 tons or more of diols per hour) and stably with high selectivity and high yield over a long period of time (for example, 1000 hours or more, preferably 3000 hours or more, and more preferably 5000 hours or more).

[0009] Methods used to solve problems

[0010] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that by adjusting the length and inner diameter of a tower, as well as the effective area ratio and open area ratio of each tray in the tower, within specific ranges, dialkyl carbonates and diols can be stably produced with high selectivity and high yield at a higher productivity (e.g., at least 1.3 times the target values ​​described in Patent Document 1 (2 tons or more of dialkyl carbonate per hour, 1.3 tons or more of diols per hour)) when industrially mass-producing dialkyl carbonates and diols with the same tower length and inner diameter, for a long period of time (e.g., 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more) and for a long period of time (e.g., 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more) thereby completing the present invention.

[0011] That is, the present invention is as follows. [1]

[0013] A method for industrially producing dialkyl carbonates and diols, wherein the dialkyl carbonates and diols are continuously produced by a reactive distillation method in which a cyclic carbonate and an aliphatic monohydric alcohol are continuously fed into a continuous multi-stage distillation column in the presence of a homogeneous catalyst, a reaction and distillation are simultaneously carried out in the column, a low-boiling-point reaction mixture containing the produced dialkyl carbonate is continuously withdrawn in a gaseous state from the upper portion of the column, and a high-boiling-point reaction mixture containing the diols is continuously withdrawn in a liquid state from the lower portion of the column.

[0014] (a) The continuous multi-stage distillation column is a tray-type distillation column having a cylindrical column body having a length L (cm) and an inner diameter D (cm) and an internal member therein, wherein the internal member is a tray having a plurality of holes, and the column has a gas extraction port at or near the top of the column, a liquid extraction port at or near the bottom of the column, one or more first inlets below the gas extraction port and in the upper and / or middle portion of the column, and one or more second inlets above the liquid extraction port and in the middle and / or lower portion of the column.

[0015] (1) The length of the tower L (cm) satisfies formula (1),

[0016] 1,500 ≤ L ≤ 12,000 Formula (1)

[0017] (2) The inner diameter D (cm) of the tower satisfies formula (2),

[0018] 120 ≤ D ≤ 3,000 Formula (2)

[0019] (3) The internal components include three types of trays: upper, middle and lower.

[0020] (4) continuously introducing the cyclic carbonate as a raw material into the continuous multi-stage distillation column from one or more first inlets, wherein the upper layer is a layer above the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the upper layer to the total number of trays is 1% to 10%,

[0021] (5) an aliphatic monohydric alcohol as a raw material is continuously introduced into the continuous multi-stage distillation column from one or more second inlets, the middle stage is a layer from the layer of the uppermost inlet among the one or more second inlets to the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the middle stage to the total number of trays is 40% to 50%,

[0022] (6) the lower layer is a layer below the layer of the uppermost inlet among the one or more second inlets, and the ratio of the number of trays in the lower layer to the total number of trays is 45% to 55%,

[0023] (7) In each lower tray, the ratio of the effective area calculated by the following formula (i) is 40% to 80%, and the ratio of the open area calculated by the following formula (ii) is 1.0% to 5.0%,

[0024] Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i)

[0025] (In formula (i), the effective area is the area of ​​the perforated zone in the tray deck (extending 4 inches outward from the boundary of the minimum zone containing all the holes), the tray area is the area of ​​the tray deck, and the tray area is the area including the effective area but excluding the downcomer portion.)

[0026] Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii)

[0027] (In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i))

[0028] (8) In each of the upper and middle trays, the ratio of the effective area calculated by the above formula (i) is 40% to 80%, and the ratio of the open area calculated by the above formula (ii) is 1.0 times or more the ratio of the open area calculated by the above formula (ii) in each of the lower trays,

[0029] (9) The homogeneous catalyst comprises a mixture of an alkali metal and ethylene glycol, wherein the mass ratio of the alkali metal to the ethylene glycol in the homogeneous catalyst (alkali metal / ethylene glycol) is 0.05 to 0.5, and the catalyst concentration (calculated as the alkali metal concentration) relative to the cyclic carbonate supplied to the distillation column is 0.05% by mass to 2.0% by mass. [2]

[0031] The method according to claim 1, wherein

[0032] In the upper layer, 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.

[0033] In the middle layer, 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.

[0034] In the lower layer, 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. [3]

[0036] The method according to [1] or [2], wherein the amount of dialkyl carbonate produced is 4.5 tons or more per hour. [4]

[0038] The method according to any one of [1] to [3], wherein the amount of diols produced is 2.5 tons or more per hour. [5]

[0040] A continuous multi-stage distillation tower is used for carrying out transesterification reaction and distillation of a cyclic carbonate and an aliphatic monohydric alcohol, wherein:

[0041] (a) The continuous multi-stage distillation column comprises: a cylindrical column body having a length L (cm) and an inner diameter D (cm); a tray having a plurality of holes disposed inside the column body as an internal member; a gas extraction port located at or near the top of the column in an upper portion of the column; a liquid extraction port located at or near the bottom of the column in a lower portion of the column; one or more first inlets located below the gas extraction port and in an upper portion and / or middle portion of the column; and one or more second inlets located above the liquid extraction port and in an upper portion and / or lower portion of the column.

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

[0043] 1,500 ≤ L ≤ 12,000 Formula (1)

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

[0045] 120 ≤ D ≤ 3,000 Formula (2)

[0046] (3) The internal components include three types of trays: upper, middle and lower.

[0047] (4) continuously introducing the cyclic carbonate as a raw material into the continuous multi-stage distillation column from one or more first inlets, wherein the upper layer is a layer above the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the upper layer to the total number of trays is 1% to 10%,

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

[0049] (6) the lower layer is a layer below the layer of the uppermost inlet among the one or more second inlets, and the ratio of the number of trays in the lower layer to the total number of trays is 45% to 55%,

[0050] (7) In each lower tray, the ratio of the effective area calculated by the following formula (i) is 40% to 80%, and the ratio of the open area calculated by the following formula (ii) is 1.0% to 5.0%,

[0051] Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i)

[0052] (In formula (i), the effective area is the area of ​​the perforated zone in the tray deck (extending 4 inches outward from the boundary of the minimum zone containing all the holes), the tray area is the area of ​​the tray deck, and the tray area is the area including the effective area but excluding the downcomer portion.)

[0053] Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii)

[0054] (In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i))

[0055] (8) In each of the upper and middle trays, the ratio of the effective area calculated by the above formula (i) is 40% to 80%, and the ratio of the open area calculated by the above formula (ii) is 1.0 times or more of the ratio of the open area calculated by the above formula (ii) in each of the lower trays.

[0056] Effects of the Invention

[0057] The present invention can stably produce dialkyl carbonate and diols with high selectivity and high yield at a higher productivity (for example, 1.3 times or more of the target values ​​described in Patent Document 1 (2 tons or more of dialkyl carbonate per hour, 1.3 tons or more of diols per hour)) when industrially mass-producing dialkyl carbonate and diols using the same tower length and inner diameter, and for a long period of time (for example, 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more). BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a diagram showing an example of a production apparatus used for producing dialkyl carbonate and glycols according to the present invention.

[0059] Figure 2 This is a schematic diagram showing an example of the structure of the trays in the continuous multi-stage distillation column used in the present invention. DETAILED DESCRIPTION

[0060] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “this embodiment”) will be described in more detail, but the present invention is not limited thereto and various modifications can be made without departing from the spirit and scope of the present invention.

[0061] In the method for industrially producing dialkyl carbonates and diols according to the present embodiment, dialkyl carbonates and diols are continuously produced by a reactive distillation method in which a cyclic carbonate and an aliphatic monohydric alcohol are used as raw materials, the raw materials are continuously supplied to a continuous multi-stage distillation column in the presence of a homogeneous catalyst, reaction and distillation are simultaneously carried out in the column, a low-boiling-point reaction mixture containing the produced dialkyl carbonate is continuously withdrawn in a gaseous state from the upper portion of the column, and a high-boiling-point reaction mixture containing the diols is continuously withdrawn in a liquid state from the lower portion of the column.

[0062] (a) The continuous multi-stage distillation column is a tray-type distillation column having a cylindrical column body having a length L (cm) and an inner diameter D (cm) and an internal member therein, wherein the internal member is a tray having a plurality of holes, and the column has a gas extraction port at or near the top of the column, a liquid extraction port at or near the bottom of the column, one or more first inlets below the gas extraction port and in the upper and / or middle portion of the column, and one or more second inlets above the liquid extraction port and in the middle and / or lower portion of the column.

[0063] (1) The length of the tower L (cm) satisfies formula (1),

[0064] 1,500 ≤ L ≤ 12,000 Formula (1)

[0065] (2) The inner diameter D (cm) of the tower satisfies formula (2),

[0066] 120 ≤ D ≤ 3,000 Formula (2)

[0067] (3) The internal components include three types of trays: upper, middle and lower.

[0068] (4) continuously introducing the cyclic carbonate as a raw material into the continuous multi-stage distillation column from one or more first inlets, wherein the upper layer is a layer above the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the upper layer to the total number of trays is 1% to 10%,

[0069] (5) an aliphatic monohydric alcohol as a raw material is continuously introduced into the continuous multi-stage distillation column from one or more second inlets, the middle stage is a layer from the layer of the uppermost inlet among the one or more second inlets to the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the middle stage to the total number of trays is 40% to 50%,

[0070] (6) the lower layer is a layer below the layer of the uppermost inlet among the one or more second inlets, and the ratio of the number of trays in the lower layer to the total number of trays is 45% to 55%,

[0071] (7) In each lower tray, the ratio of the effective area calculated by the following formula (i) is 40% to 80%, and the ratio of the open area calculated by the following formula (ii) is 1.0% to 5.0%,

[0072] Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i)

[0073] (In formula (i), the effective area is the area of ​​the perforated zone in the tray deck (extending 4 inches outward from the boundary of the minimum zone containing all the holes), the tray area is the area of ​​the tray deck, and the tray area is the area including the effective area but excluding the downcomer portion.)

[0074] Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii)

[0075] (In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i))

[0076] (8) In each of the upper and middle trays, the ratio of the effective area calculated by the above formula (i) is 40% to 80%, and the ratio of the open area calculated by the above formula (ii) is 1.0 times or more the ratio of the open area calculated by the above formula (ii) in each of the lower trays,

[0077] (9) The homogeneous catalyst comprises a mixture of an alkali metal and ethylene glycol, wherein the mass ratio of the alkali metal to the ethylene glycol in the homogeneous catalyst (alkali metal / ethylene glycol) is 0.05 to 0.5, and the catalyst concentration (calculated as the alkali metal concentration) relative to the cyclic carbonate supplied to the distillation column is 0.05% by mass to 2.0% by mass.

[0078] The manufacturing method of this embodiment adopts the above-mentioned structure, and when manufacturing dialkyl carbonates and diols industrially, it is possible to stably manufacture dialkyl carbonates and diols with higher productivity (for example, more than 4.5 tons of dialkyl carbonate per hour, and more than 2.7 tons of diols per hour) and with high selectivity and high yield for a long period of time (for example, more than 1000 hours, preferably more than 3000 hours, and more preferably more than 5000 hours).

[0079] The reaction utilized in the production method of the present embodiment is a reversibly balanced transesterification reaction represented by the following formula, in which a cyclic carbonate (A) and an aliphatic monohydric alcohol (B) are used to produce a dialkyl carbonate (C) and a diol (D).

[0080]

[0081] (In the formula, R l Represents a divalent group -(CH2) m - (m is an integer of 2 to 6), wherein one or more hydrogen atoms may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms. 2represents a monovalent aliphatic group having 1 to 12 carbon atoms, in which one or more hydrogen atoms may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms)

[0082] In the manufacturing method of the present embodiment, the cyclic carbonate used as a raw material refers to a compound represented by (A) in the above formula. As the cyclic carbonate, for example, alkylene carbonates such as ethylene carbonate and propylene carbonate can be preferably used; 1,3-dioxane-2-one, 1,3-dioxepane-2-one, etc., are more preferably used from the aspects of easy availability, and ethylene carbonate and propylene carbonate are particularly preferably used.

[0083] In addition, the aliphatic monohydric alcohols as another raw material refer to the compound represented by (B) in the above formula. As aliphatic monohydric alcohols, it is preferred to use aliphatic monohydric alcohols with a boiling point lower than the dihydric alcohols generated. Therefore, as aliphatic monohydric alcohols, it is possible to change according to the type of cyclic carbonate used, for example, methanol, ethanol, propanol (each isomer), allyl alcohol, butanol (each isomer), 3-butene-1-ol, amyl alcohol (each isomer), hexanol (each isomer), heptanol (each isomer), octanol (each isomer), nonanol (each isomer), decanol (each isomer), undecanol (each isomer), dodecanol (each isomer), cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol , methylcyclopentanol (each isomer), ethylcyclopentanol (each isomer), methylcyclohexanol (each isomer), ethylcyclohexanol (each isomer), dimethylcyclohexanol (each isomer), diethylcyclohexanol (each isomer), phenylcyclohexanol (each isomer), benzyl alcohol, phenylethyl alcohol (each isomer), phenylpropanol (each isomer), etc. In addition, these aliphatic monohydric alcohols may be substituted by halogen, lower alkoxy, cyano, alkoxycarbonyl, aryloxycarbonyl, acyloxy, nitro and other substituents.

[0084] Among such aliphatic monohydric alcohols, alcohols having 1 to 6 carbon atoms are preferably used, and alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propanol (each isomer), and butanol (each isomer) are more preferably used. When ethylene carbonate or propylene carbonate is used as the cyclic carbonate, methanol or ethanol is preferred, and methanol is particularly preferred.

[0085] In the production method of this embodiment, a cyclic carbonate as a raw material is continuously introduced into a continuous multi-stage distillation column from one or more first inlets, and an aliphatic monohydric alcohol as a raw material is continuously introduced into the continuous multi-stage distillation column from one or more second inlets. By continuously introducing each raw material into the continuous multi-stage distillation column from these locations, optimal reaction efficiency between the dialkyl carbonate and the diol can be achieved, ensuring sufficient production volume. Furthermore, optimal separation performance can be achieved, ensuring sufficient dialkyl carbonate and diol supplies.

[0086] In the production method of this embodiment, a homogeneous catalyst is placed in the reactive distillation column. The method for placing the homogeneous catalyst in the reactive distillation column may be any method, but it is preferably to place the catalyst in the liquid phase in the reactive distillation column by continuously supplying the catalyst into the reactive distillation column.

[0087] When a homogeneous catalyst is continuously supplied to the reactive distillation column, it may be supplied simultaneously with the cyclic carbonate and / or aliphatic monohydric alcohol, or it may be supplied to a location different from the raw materials. Since the actual reaction region within the distillation column extends downward from the catalyst supply location, the catalyst is preferably supplied to the region between the column top and the raw materials supply location. Furthermore, the number of layers containing the catalyst is preferably 5 or more, more preferably 7 or more, and even more preferably 10 or more.

[0088] The catalyst used in the manufacture method of the present embodiment is a compound formed by a mixture of an alkali metal and ethylene glycol. In addition, the mass ratio of the alkali metal to the ethylene glycol in this homogeneous catalyst (alkali metal / ethylene glycol) is 0.05 to 0.5, preferably 0.1 to 0.4, more preferably 0.2 to 0.3. When the mass ratio of the alkali metal to the ethylene glycol (alkali metal / ethylene glycol) is within the above range, it is possible to suppress the generation of impurities while promoting the generation of dialkyl carbonate and diols. In addition, relative to the cyclic carbonate (such as ethylene carbonate (EC)) supplied to the distillation column, the catalyst concentration (converted by the alkali metal concentration) is 0.05% to 2.0% by mass.

[0089] The alkali metal in the catalyst used in the production method of the present embodiment is not particularly limited, and examples thereof include lithium, potassium, sodium, and cesium, with potassium and sodium being preferred.

[0090] The amount of the catalyst used in the production method of the present embodiment (calculated as alkali metal concentration) is generally 0.05 to 2.0 mass %, preferably 0.1 to 1.0 mass %, and more preferably 0.5 to 1.0 mass %, expressed as a ratio to the mass of the cyclic carbonate supplied as a raw material.

[0091] When the amount of catalyst is above the above lower limit, the reaction and yield are sufficient, and the production volume is improved. In addition, when the amount of catalyst is below the above upper limit, impurities (high boiling point components) are suppressed, and the product purity is improved. In addition, it is possible to prevent a portion of the catalyst from being extracted outside the system along with the impurities (high boiling point components), thereby reducing catalyst loss.

[0092] In the manufacturing method of the present embodiment, when cyclic carbonate is continuously supplied to a continuous multi-stage distillation tower (for example, number of layers n) as a reactive distillation tower, cyclic carbonate is preferably supplied to a specific layer. For example, it is preferred that the cyclic carbonate as a raw material is continuously introduced into the continuous multi-stage distillation tower from one or more inlets arranged below the third layer from the top of the continuous multi-stage distillation tower and above the (n / 3)th layer from the top of the continuous multi-stage distillation tower. The layers upward from the cyclic carbonate inlet are preferably such that high boiling point compounds such as the cyclic carbonate and diols are not included in the tower top component. In this sense, the layers upward from the cyclic carbonate inlet are preferably more than 3 layers, more preferably 4 to 10 layers, and further preferably 5 to 8 layers.

[0093] In the production method of the present embodiment, the internal components in the continuous multi-stage distillation column include three types of trays: upper, middle, and lower trays.

[0094] The upper layer is a layer higher than the layer of the topmost inlet among one or more first inlets, the middle layer is a layer from the layer of the topmost inlet among one or more second inlets to the layer of the topmost inlet among one or more first inlets, and the lower layer is a layer lower than the layer of the topmost inlet among one or more second inlets.

[0095] In the production method of this embodiment, the total number n of layers of the upper layer, the middle layer, and the lower layer is preferably 10 to 100 layers, more preferably 30 to 100 layers, and even more preferably 30 to 80 layers.

[0096] In addition, in the production method of this embodiment, the proportion of the number of trays in the upper layer is 1% to 10% of the total number of layers, preferably 3% to 10%, and more preferably 5% to 10%. In addition, the proportion of the number of trays in the middle layer is 40% to 50% of the total number of layers, preferably 40% to 45%, and more preferably 40% to 43%. In addition, the proportion of the number of trays in the lower layer is 45% to 55% of the total number of layers, preferably 48% to 55%, and more preferably 50% to 55%. By setting the ratio of the upper layer, the middle layer, and the lower layer within the above range, the optimal reaction efficiency of the dialkyl carbonate and the diols can be achieved, sufficient production can be ensured, and optimal separation performance can be achieved, which can ensure sufficient dialkyl carbonate and diols.

[0097] The preferred cyclic carbonate that uses in the present embodiment is for example the cyclic carbonate that does not contain halogen that manufactures by the reaction of alkylene oxides such as oxyethane, propylene oxide, phenyl ethylene oxide and carbonic acid gas.Therefore, also can use the cyclic carbonate that comprises a spot of these feedstock compounds, diols etc. as the raw material of present embodiment.As cyclic carbonate, also can be the cyclic carbonate that derives from biomass.For example can enumerate: the cyclic carbonate that obtains as raw material with bioethanol.

[0098] In this 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, it is preferred to use an aliphatic monohydric alcohol containing 1% to 15% by mass of dialkyl carbonate relative to the total mass of the aliphatic monohydric alcohol and the dialkyl carbonate, more preferably 1.5% to 12% by mass of dialkyl carbonate, and even more preferably 2% to 10% by mass of dialkyl carbonate.

[0099] When implementing this reaction industrially, it is preferred that in addition to being able to use cyclic carbonate and / or aliphatic monohydric alcohol newly introduced into the reaction system as raw materials, it is also possible to use materials with cyclic carbonate and / or aliphatic monohydric alcohol as main components recovered in this process and / or other processes as their raw materials. The manufacturing method of this embodiment can achieve this, which is one of the excellent features of the manufacturing method of this embodiment. Other processes are not particularly limited, for example, can be listed as the process of manufacturing diaryl carbonate from dialkyl carbonate and aromatic monohydroxy compound. In this process, aliphatic monohydric alcohol is generated as a by-product and is recovered. Dialkyl carbonate is usually included in the aliphatic monohydric alcohol generated as a by-product of this recovery. When its content is within the above-mentioned range, the excellent effect of the manufacturing method of this embodiment can be further demonstrated. In addition, aromatic monohydroxy compound, alkyl aryl ether, a small amount of alkyl carbonate aryl ester, diaryl carbonate, etc. are sometimes contained in the aliphatic monohydric alcohol generated as a by-product of this recovery. In the production method of this embodiment, the aliphatic monohydric alcohol produced as a by-product can be used as a raw material directly, or can be used as a raw material after reducing the content of substances having a boiling point higher than the aliphatic monohydric alcohol by distillation or the like.

[0100] In the production method of this embodiment, when continuously supplying an aliphatic monohydric alcohol to a continuous multi-stage distillation column (e.g., having n stages) serving as a reactive distillation column, the aliphatic monohydric alcohol is preferably supplied to a specific stage. For example, in the production method of this embodiment, the aliphatic monohydric alcohol as a raw material is preferably continuously introduced into the continuous multi-stage distillation column from one or more inlets located between the (n / 3)th stage or lower and the (2n / 3)th stage or higher from the top of the continuous multi-stage distillation column. In the production method of this embodiment, when the aliphatic monohydric alcohol used as a raw material contains a specific amount of dialkyl carbonate, the excellent effects of the production method of this embodiment can be further demonstrated by setting the inlet to a specific stage. More preferably, the aliphatic monohydric alcohol is continuously introduced into the continuous multi-stage distillation column from one or more inlets located between the (2n / 5)th stage or lower and the (3n / 5)th stage or higher from the top of the continuous multi-stage distillation column.

[0101] The raw materials are preferably continuously supplied to the distillation column in a liquid, gaseous, or liquid-gas mixture. In addition to supplying the raw materials to the distillation column in this manner, a method in which a gaseous raw material is intermittently or continuously supplied from the center and / or lower portion of the distillation column is also preferred. Furthermore, a method in which the cyclic carbonate is continuously supplied to the distillation column in a liquid state or a gas-liquid mixture from one or more inlets located above the catalyst layer, and the aliphatic monohydric alcohol is continuously supplied to the distillation column in a gaseous and / or liquid state from one or more inlets located in the aforementioned layers, is also preferred. Furthermore, it is preferred that these raw materials contact the catalyst in at least five layers, preferably at least seven layers, and more preferably at least ten layers, of the distillation column.

[0102] In the production method of this embodiment, the ratio of the cyclic carbonate to the aliphatic monohydric alcohol supplied to the reactive distillation column varies depending on the type and amount of the transesterification catalyst and the reaction conditions. However, it is preferable to supply the aliphatic monohydric alcohol in a molar ratio ranging from 0.01 to 1,000 times the amount of the supplied cyclic carbonate. To increase the conversion rate of the cyclic carbonate, it is preferable to supply an excess of at least 2 times the molar amount of the aliphatic monohydric alcohol. However, using an excessive amount of the aliphatic monohydric alcohol may require an increase in the size of the equipment. Therefore, the molar ratio of the aliphatic monohydric alcohol to the cyclic carbonate is preferably 2 to 20, more preferably 3 to 15, and even more preferably 5 to 12. It should be noted that if a large amount of unreacted cyclic carbonate remains, it reacts with the diols produced as products to form by-products such as dimers and trimers. Therefore, in industrial practice, it is preferable to minimize the amount of unreacted cyclic carbonate. In the production method of this embodiment, even if the molar ratio is 10 or less, the reaction rate of the cyclic carbonate can be 98% or more, preferably 99% or more, and more preferably 99.9% or more. This is also one of the characteristics of the production method of this embodiment.

[0103] In the manufacture method of present embodiment, preferably can manufacture the dialkyl carbonate more than 4.5 tons continuously in per 1 hour, for this reason, the minimum amount of the cyclic carbonate that supplies with continuously is generally 2.0p tons / hour with respect to the amount (p tons / hour) of the dialkyl carbonate that will manufacture, is preferably 1.5p tons / hour, more preferably 1.3p tons / hour.Under further preferred situation, can be less than 1.0p tons / hour.

[0104] Figure 1This is a schematic diagram showing an example of a continuous multi-stage distillation column used in the production method of this embodiment. The continuous multi-stage distillation column 10 used in the production method of this embodiment is a tray-type distillation column having a structure including end plates 5 above and below a cylindrical column body 7 having a length L (cm) and an inner diameter D (cm), and internal components having n layers therein, wherein the internal components are trays having multiple holes. The continuous multi-stage distillation column 10 includes: a gas extraction port 1 having an inner diameter d1 (cm) located at or near the top of the column; a liquid extraction port 2 having an inner diameter d2 (cm) located at or near the bottom of the column; and a liquid extraction port 2 located below the gas extraction port 1 and disposed on the continuous multi-stage distillation column. In order to simultaneously perform distillation and reaction, and to stably produce preferably 4.5 tons or more of dialkyl carbonate per hour and / or preferably 2.5 tons or more of glycols per hour for a long period of time, at least one first inlet 3 (a, e) located between the third stage and below and the (n / 3)th stage and above from the top of the continuous multi-stage distillation column, and at least one second inlet 3 (b, c) and 4 (a, b) located above the liquid extraction port 2 and provided between the (n / 3)th stage and below and the (2n / 3)th stage and above from the top of the continuous multi-stage distillation column, it is preferable to satisfy various conditions. It should be noted that Figure 1 This is one embodiment of the continuous multi-stage distillation column used in the production method of this embodiment, and therefore, the arrangement of the trays is not limited to Figure 1 The composition shown.

[0105] The continuous multi-stage distillation column of this embodiment satisfies not only the requirements for simple distillation function but also the requirements for stably carrying out the reaction at a high reaction rate and high selectivity. Specifically, the continuous multi-stage distillation column of this embodiment is a continuous multi-stage distillation column for carrying out the transesterification reaction and distillation of a cyclic carbonate and an aliphatic monohydric alcohol, wherein:

[0106] (a) The continuous multi-stage distillation column comprises: a cylindrical column body having a length L (cm) and an inner diameter D (cm); a tray having a plurality of holes disposed inside the column body as an internal member; a gas extraction port located at or near the top of the column in an upper portion of the column; a liquid extraction port located at or near the bottom of the column in a lower portion of the column; one or more first inlets located below the gas extraction port and in an upper portion and / or middle portion of the column; and one or more second inlets located above the liquid extraction port and in an upper portion and / or lower portion of the column.

[0107] (1) The length of the tower L (cm) satisfies formula (1),

[0108] 1,500 ≤ L ≤ 12,000 Formula (1)

[0109] (2) The inner diameter D (cm) of the tower satisfies formula (2),

[0110] 120 ≤ D ≤ 3,000 Formula (2)

[0111] (3) The internal components include three types of trays: upper, middle and lower.

[0112] (4) continuously introducing the cyclic carbonate as a raw material into the continuous multi-stage distillation column from one or more first inlets, wherein the upper layer is a layer above the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the upper layer to the total number of trays is 1% to 10%,

[0113] (5) an aliphatic monohydric alcohol as a raw material is continuously introduced into the continuous multi-stage distillation column from one or more second inlets, the middle stage is a layer from the layer of the uppermost inlet among the one or more second inlets to the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the middle stage to the total number of trays is 40% to 50%,

[0114] (6) the lower layer is a layer below the layer of the uppermost inlet among the one or more second inlets, and the ratio of the number of trays in the lower layer to the total number of trays is 45% to 55%,

[0115] (7) In each lower tray, the ratio of the effective area calculated by the following formula (i) is 40% to 80%, and the ratio of the open area calculated by the following formula (ii) is 1.0% to 5.0%,

[0116] Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i)

[0117] (In formula (i), the effective area is the area of ​​the perforated zone in the tray deck (extending 4 inches outward from the boundary of the minimum zone containing all the holes), the tray area is the area of ​​the tray deck, and the tray area is the area including the effective area but excluding the downcomer portion.)

[0118] Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii)

[0119] (In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i))

[0120] (8) In each of the upper and middle trays, the ratio of the effective area calculated by the above formula (i) is 40% to 80%, and the ratio of the open area calculated by the above formula (ii) is 1.0 times or more of the ratio of the open area calculated by the above formula (ii) in each of the lower trays.

[0121] It should be noted that the above-mentioned requirements (1) to (8) in the continuous multi-stage distillation column of the present embodiment are the same as the requirements (1) to (8) in the production method of the present embodiment.

[0122] In the production method of the present embodiment, in the upper layer, the gas flow rate is preferably 5,000 to 45,000 kg / hour, and the liquid flow rate is preferably 1,000 to 15,000 kg / hour.

[0123] In the production method of the present embodiment, in the middle layer, the gas flow rate is preferably 5,000 to 30,000 kg / hour, and the liquid flow rate is preferably 1,000 to 15,000 kg / hour.

[0124] In the production method of the present embodiment, in the lower layer, the gas flow rate is preferably 5,000 to 20,000 kg / hour, and the liquid flow rate is preferably 1,000 to 30,000 kg / hour.

[0125] In addition, in the production method of the present embodiment, the amount of dialkyl carbonate produced is preferably 4.5 tons or more per hour.

[0126] In the production method of the present embodiment, the amount of glycols produced is preferably 2.5 tons or more per hour.

[0127] It should be noted that the term "tower top or the upper portion of the tower near the top" used in this embodiment refers to the portion from the tower top to approximately 0.25 L downward, and the term "tower bottom or the lower portion of the tower near the bottom" refers to the portion from the tower bottom to approximately 0.25 L upward. "L" is defined as above.

[0128] The production method of this embodiment is a reactive distillation method that not only performs simple distillation but also conducts a reaction simultaneously, and achieves a high reaction rate and high selectivity (high yield). To this end, it was discovered that it is important to set the layers of the respective raw material inlets and the effective area and open area of ​​each tray within specific ranges in addition to the above-mentioned formulas (1) and (2). The preferred ranges of each factor are as follows.

[0129] When L (cm) is 1,500 or greater, the reaction rate is improved, thereby achieving the target production volume. When L (cm) is 12,000 or less, the equipment cost can be reduced while maintaining a reaction rate sufficient to achieve the target production volume. The preferred range of L (cm) is 2,000 ≤ L ≤ 15,000, more preferably 2,200 ≤ L ≤ 10,000, and even more preferably 2,500 ≤ L ≤ 5,000.

[0130] Furthermore, when D (cm) is 120 or greater, the target production volume can be achieved, and when D (cm) is 3,000 or less, the target production volume can be achieved while reducing equipment costs. The preferred range of D (cm) is 150 ≤ D ≤ 2,000, more preferably 180 ≤ D ≤ 1,200, and even more preferably 210 ≤ D ≤ 800.

[0131] The continuous multi-stage distillation column used in this embodiment is preferably a tray-type distillation column equipped with n layers of trays having multiple holes as internal components. The term "internal components" in this embodiment refers to the portion of the distillation column where gas-liquid contact actually occurs. Preferred examples of such trays include bubble cap trays, perforated trays, corrugated trays, heavy-disc valve trays, valve trays, countercurrent trays, S-shaped trays, Superfrac trays, Maxfrac trays, dual-flow trays, grid trays, crossflow grid trays, Kittel trays, and high-performance trays such as UFM (manufactured by Sulzer). Even when the continuous multi-stage distillation column includes a layer (e.g., a layer above the catalyst introduction layer) where no catalyst is present and no reaction occurs, it is preferable to configure the distillation column such that the layer is filled with packing, that is, to configure the multi-stage distillation column to include both a tray portion and a portion filled with packing. Preferred examples of such packings include random packings such as Raschig rings, Lessing rings, Pall rings, Bell saddle rings, rectangular saddle rings, Dixon packing, McMahon packing, and Helipak; and structured packings such as Mellapak, Gempak, Techno-pack, Flexipac, Sulzer packing, Goodroll packing, and Glitsch grid. It should be noted that the term "number of stages n" 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. Therefore, the number of stages n in a multi-stage distillation column having both tray sections and sections filled with packing is the sum of the number of trays and the theoretical number of stages.

[0132] In the production method of this embodiment, any of the above-mentioned trays of n layers can achieve high reaction rate, high selectivity and high productivity. However, from the perspective of the relationship between function and equipment cost, it is particularly preferred that the tray has a perforated plate portion (tray deck portion) and a downcomer portion. In addition, the perforated plate tray preferably has a perforated plate portion per 1m 2The porous plate portion has 100 to 1,000 holes per area. More preferably, the number of holes per 1 m 2 The number of holes in the area of ​​the perforated plate portion is 120 to 900, more preferably 150 to 800. In addition, the cross-sectional area of ​​each hole of the perforated plate is preferably 0.5 cm 2 ~5cm 2 More preferably, the cross-sectional area of ​​each hole is 0.7 cm 2 ~4cm 2 , more preferably 0.9 cm 2 ~3cm 2 In addition, it is particularly preferred that the perforated plate has a 2 The porous plate has 100 to 1,000 holes and the cross-sectional area of ​​each hole is 0.5 cm 2 ~5cm 2 In addition, the number of holes in the porous plate portion may be the same or different in all the porous plates as long as the requirements of (7) and (8) above are satisfied.

[0133] Figure 2 A schematic diagram showing an example of the structure of the trays in the continuous multi-stage distillation column used in this embodiment. Figure 2 As shown, the tray in the distillation tower has a downcomer portion 11 and a tray platform portion 13, and the tray platform portion 13 has holes 14 (in Figure 2 The partition (where the portion indicated by the small circle represents each hole) of the column (the range extending 4 inches outward from the boundary 15 of the minimum area including all the holes) is the effective area 12. In this effective area 12, the liquid and the vapor are actually in contact during the distillation process. In addition, in this downcomer section 13, the liquid bubbling on the tray deck section 13 is separated into liquid and vapor, and only the liquid is transferred to the lower layer.

[0134] The ratio of the effective area of ​​each tray used in the present embodiment is calculated by the following formula (i).

[0135] Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i)

[0136] (In formula (i), the effective area is the area of ​​the perforated zone in the tray deck (extending 4 inches outward from the boundary of the minimum zone containing all the holes), the tray area is the area of ​​the tray deck, and the tray area is the area including the effective area but excluding the downcomer portion.)

[0137] In addition, the ratio of the open area of ​​each tray used in the present embodiment is calculated by the following formula (ii).

[0138] Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii)

[0139] (In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i))

[0140] In addition, in each of the upper and middle trays used in this embodiment, the ratio (%) of the effective 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, in each of the lower trays used in this embodiment, the ratio (%) of the effective 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, in each of the lower trays used in this 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 further preferably 2.0% to 3.5%. In addition, in each of the upper and middle trays used in this embodiment, the ratio (%) of the open area calculated by the above formula (ii) is 1.0 times or more of the ratio of the open area calculated by the above formula (ii) in each of the lower trays, preferably 1.0 times to 6.0 times, more preferably 1.0 times to 3.0 times, and even more preferably 1.0 times to 1.5 times.

[0141] By setting the ratio of effective area to open area on each of the upper, middle, and lower trays to be above the aforementioned lower limit, the differential pressure within the column is reduced, the processing capacity is improved, the reaction proceeds sufficiently, the yield is increased, and the production volume is increased. Furthermore, by setting the ratio of effective area to open area on each of the upper, middle, and lower trays to be below the aforementioned upper limit, separation from the reaction product is sufficient, product purity is improved, the reaction proceeds sufficiently, the yield is increased, and the production volume is increased.

[0142] When the production method of this embodiment is implemented, it is preferable to control the gas flow rate and the liquid flow rate in the upper layer, the middle layer, and the lower layer, respectively.

[0143] In the upper layer used in this embodiment, the gas flow rate (kg / hour) is preferably 5,000 kg / hour to 45,000 kg / hour, more preferably 10,000 kg / hour to 25,000 kg / hour, and even more preferably 15,000 kg / hour to 25,000 kg / hour.

[0144] In the middle layer used in this embodiment, the gas flow rate (kg / hour) is preferably 5,000 kg / hour to 30,000 kg / hour, more preferably 10,000 kg / hour to 25,000 kg / hour, and even more preferably 10,000 kg / hour to 20,000 kg / hour.

[0145] In the lower layer used in the present embodiment, the gas flow rate (kg / hour) is preferably 5,000 kg / hour to 20,000 kg / hour, and more preferably 5,000 kg / hour to 10,000 kg / hour.

[0146] In the upper layer used in this embodiment, the liquid flow rate (kg / hour) is preferably 1,000 kg / hour to 15,000 kg / hour, more preferably 3,000 kg / hour to 10,000 kg / hour, and even more preferably 4,000 kg / hour to 8,000 kg / hour.

[0147] In the middle layer used in this embodiment, the liquid flow rate (kg / hour) is preferably 1,000 kg / hour to 15,000 kg / hour, more preferably 3,000 kg / hour to 10,000 kg / hour, and even more preferably 3,000 kg / hour to 8,000 kg / hour.

[0148] In the lower layer used in this embodiment, the liquid flow rate (kg / hour) is preferably 1,000 kg / hour to 30,000 kg / hour, more preferably 5,000 kg / hour to 20,000 kg / hour, and even more preferably 5,000 kg / hour to 15,000 kg / hour.

[0149] When the gas flow rate and liquid flow rate of each of the upper layer, middle layer, and lower layer used in the present embodiment are set to above the above lower limit, the reaction product is fully separated, the product purity is improved, the reaction is fully carried out, the yield is improved, and the throughput is increased. In addition, when the gas flow rate and liquid flow rate of each of the upper layer, middle layer, and lower layer used in the present embodiment are set to below the above upper limit, the differential pressure in the tower is reduced, the processing capacity is improved, the reaction is fully carried out, the yield is improved, and the throughput is increased.

[0150] By adding the above-mentioned conditions to the continuous multi-stage distillation column, the object of the present invention can be achieved more easily.

[0151] When the production method of the present embodiment is implemented, cyclic carbonates and aliphatic monohydric alcohols as raw materials are continuously supplied to a continuous multi-stage distillation column in the presence of a catalyst. Reaction and distillation are simultaneously carried out in the column. A low-boiling-point reaction mixture containing the produced dialkyl carbonate is continuously extracted in a gaseous state from the upper portion of the column, and a high-boiling-point reaction mixture containing glycols is continuously extracted in a liquid state from the lower portion of the column, thereby continuously producing dialkyl carbonate and glycols.

[0152] The reaction time of the transesterification reaction carried out by the production method of the present embodiment can be considered to correspond to the average residence time of the reaction liquid in the continuous multi-stage distillation column. The reaction time varies depending on the shape of the internal components of the distillation column, the number of stages, the amount of raw materials supplied, the type and amount of the catalyst, the 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.

[0153] The reaction temperature of the transesterification reaction carried out by the manufacturing method of the present embodiment varies depending on the type of raw material compound used, the type and amount of the catalyst, and is preferably 30°C to 300°C. In order to increase the reaction rate, it is preferred to increase the reaction temperature, but when the reaction temperature is high, side reactions are also likely to occur. Therefore, the more preferred reaction temperature is in the range of 40°C to 250°C, further preferably in the range of 50°C to 200°C, and particularly preferably in the range of 60°C to 150°C. In the manufacturing method of the present embodiment, the reaction distillation can be carried out with the bottom temperature preferably being 150°C or less, more preferably 130°C or less, further preferably 110°C or less, and more preferably 100°C or less. Even at such a low bottom temperature, high reaction rate, high selectivity and high productivity can be achieved, which is one of the excellent features of the present invention. In addition, the reaction pressure of the transesterification reaction carried out by the manufacturing method of the present embodiment varies depending on the type and composition of the raw material compound used, the reaction temperature, etc., and can be any of reduced pressure, normal pressure, and pressurized pressure, and is preferably 1Pa to 2×10 7 Pa, more preferably 10 3 Pa~10 7 Pa, more preferably 10 4 Pa~5×10 6 Pa.

[0154] The material constituting the continuous multi-stage distillation column used in this embodiment is not particularly limited. Examples thereof include metal materials such as carbon steel and stainless steel. Stainless steel is preferred from the perspective of the quality of the produced dialkyl carbonate and glycols.

[0155] Example

[0156] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[0157] [Example 1]

[0158] Continuous multi-stage distillation column

[0159] Use as Figure 1 The column shown is a continuous multi-stage distillation column (plate-type distillation column) having a column length L of 3300 cm, a column inner diameter D of 300 cm, an L / D ratio of 11, a number of stages n of 60, a ratio of the column inner diameter D to the inner diameter d1 of the gas extraction port (D / d1) of 7.5, and a ratio of the column inner diameter D to the inner diameter d2 of the liquid extraction port (D / d2) of 12. The trays of this distillation column are perforated trays having a plurality of holes, and the cross-sectional area of ​​each hole in the perforated tray is approximately 1.3 cm. 2 . In addition, the structure of the internal components (tower plates) of the distillation tower varies depending on the location of the installation, and has a structure of three types of trays: upper, middle, and lower. The upper layer is a layer above the inlet for cyclic carbonate (ethylene carbonate) (the inlet (3-a) installed at the 5th layer from the top of the distillation tower). The number of trays in the upper layer is 5, and it accounts for 8.3% of the total number of layers 60. In addition, the ratio of the effective area of ​​each tray in the upper layer is 45%, and the ratio of the open area is 4.5%. In addition, the middle layer is the layer of the inlet for cyclic carbonate (ethylene carbonate) (the inlet (3-a) installed at the 5th layer from the top of the distillation tower) and the layers below it, and the layer of the inlet for aliphatic monohydric alcohol (methanol) (the inlets (3-b) and (3-c) installed at the 30th layer from the top of the distillation tower) and the layers above it. The number of trays in the middle stage is 24, accounting for 40% of the total number of stages (60). Furthermore, the effective area of ​​each tray in the middle stage is 45%, and the open area is 3.5%. Furthermore, the lower stage is located below the inlet for the aliphatic monohydric alcohol (methanol) (inlet ports (3-b) and (3-c) located at the 30th stage from the top of the distillation column). The number of trays in the lower stage is 31, accounting for 51.7% of the total number of stages (60). Furthermore, the effective area of ​​each tray in the lower stage is 45%, and the open area is 3.0%.

[0160] <Reactive distillation>

[0161] exist Figure 1In the continuous multi-stage distillation column shown, liquid ethylene carbonate was continuously introduced into the distillation column at a flow rate of 4.7 tons / hour from an inlet (3-a) provided on the fifth stage from the top of the distillation column. Gaseous methanol (containing 8.8% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 4.622 tons / hour from an inlet (3-b) provided on the 30th stage from the top of the distillation column. Liquid methanol (containing 6.5% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 10.695 tons / hour from an inlet (3-c) provided on the 30th stage from the top of the distillation column.

[0162] The catalyst comprises a mixture of an alkali metal and ethylene glycol, and the mass ratio of the alkali metal to the ethylene glycol in the catalyst (alkali metal / ethylene glycol) is in the range of 0.2 to 0.3. The catalyst is a homogeneous catalyst synthesized by adding 4.8 tons of ethylene glycol to 2.5 tons of an alkali metal (potassium), and then heating to about 130°C and heating at about 1300 Pa for about 3 hours to prepare a homogeneous solution. The homogeneous catalyst solution is continuously introduced into the distillation tower from the inlet (3-e) provided at the 54th layer from the bottom of the distillation tower (catalyst concentration (calculated as alkali metal concentration): 1.0% by mass relative to the supplied ethylene carbonate). The temperature at the bottom of the tower is 98°C, and the pressure at the top of the tower is about 1.118×10 5 Reactive distillation was carried out continuously under the conditions of Pa and a reflux ratio of 0.52.

[0163] In the upper layer of the tower during reactive distillation, the gas flow rate is in the range of 19,600 kg / hour to 23,000 kg / hour, and the liquid flow rate is in the range of 6,000 kg / hour to 7,700 kg / hour; in the middle layer of the tower, the gas flow rate is in the range of 9,250 kg / hour to 16,000 kg / hour, and the liquid flow rate is in the range of 5,800 kg / hour to 6,500 kg / hour; in the lower layer of the tower, the gas flow rate is in the range of 5,280 kg / hour to 10,000 kg / hour, and the liquid flow rate is in the range of 7,980 kg / hour to 14,900 kg / hour.

[0164] After 24 hours, stable, steady-state operation was achieved. The low-boiling-point reaction mixture, extracted in a gaseous state from the gas extraction port 1 at the top of the tower, was cooled in a heat exchanger and converted to a liquid. The proportion of dimethyl carbonate in the liquid low-boiling-point reaction mixture, continuously extracted from the distillation tower at a rate of 15.246 tons / hour, was 5.283 tons / hour, and the proportion of methanol was 8.429 tons / hour. The proportion of ethylene glycol in the liquid continuously extracted from the liquid extraction port 2 at the bottom of the tower at a rate of 4.883 tons / hour 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 production of dimethyl carbonate per hour, after deducting the dimethyl carbonate contained in the raw materials, was 4.651 tons, and the actual production of ethylene glycol per hour, after deducting 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 more, and the selectivity of ethylene glycol was 99.99% or more.

[0165] Under this condition, long-term continuous operation was carried out. After 500 hours, 2000 hours, 4000 hours, 5000 hours and 6000 hours of continuous operation, the actual production of dimethyl carbonate per hour was 4.661 tons, 4.682 tons, 4.661 tons, 4.661 tons and 4.692 tons respectively, the actual production of ethylene glycol per hour was 2.982 tons, 2.955 tons, 2.9222 tons, 2.952 tons and 2.996 tons respectively, and the actual production of ethylene carbonate per hour was 2.967 tons, 2.966 tons, 2.947 tons and 2.966 tons respectively. The reaction rates of esters were 99.89%, 99.90%, 99.90%, 99.88% and 99.92% respectively; the selectivities of dimethyl carbonate were above 99.99%, above 99.99%, above 99.99%, above 99.99% and above 99.99% respectively; and the selectivities of ethylene glycol were above 99.99%, above 99.99%, above 99.99%, above 99.99% and above 99.99% respectively.

[0166] [Example 2]

[0167] Continuous multi-stage distillation column

[0168] Reactive distillation was conducted using the same continuous multi-stage distillation column as in Example 1, with the tray configuration modified as follows. On each upper tray, the effective area ratio was 60%, and the open area ratio was 5.0%. On each middle tray, the effective area ratio was 60%, and the open area ratio was 4.0%. On each lower tray, the effective area ratio was 45%, and the open area ratio was 3.5%.

[0169] <Reactive distillation>

[0170] Reactive distillation was continuously performed under the same conditions as in Example 1 except for the conditions described below.

[0171] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) provided at the 54th layer from the bottom of the distillation column (catalyst concentration (calculated as alkali metal concentration): 0.5% by mass relative to the supplied 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 5 Reactive distillation was continuously carried out under the conditions of Pa and a reflux ratio of 0.6.

[0172] In the upper layer of the tower during reactive distillation, the gas flow rate is in the range of 21,200 kg / hour to 24,500 kg / hour, and the liquid flow rate is in the range of 4,730 kg / hour to 6,250 kg / hour; in the middle layer, the gas flow rate is in the range of 10,040 kg / hour to 19,200 kg / hour, and the liquid flow rate is in the range of 4,630 kg / hour to 6,000 kg / hour; in the lower layer, the gas flow rate is in the range of 6,170 kg / hour to 9,490 kg / hour, and the liquid flow rate is in the range of 7,200 kg / hour to 14,100 kg / hour.

[0173] After 24 hours, stable, steady-state operation was achieved. The low-boiling-point reaction mixture, extracted in a gaseous state from the gas extraction port 1 at the top of the tower, was cooled in a heat exchanger and converted to a liquid. The proportion of dimethyl carbonate in the liquid low-boiling-point reaction mixture, continuously extracted from the distillation tower at a rate of 15.246 tons / hour, was 5.577 tons / hour, and the proportion of methanol was 8.898 tons / hour. The proportion of ethylene glycol in the liquid continuously extracted from the liquid extraction port 2 at the bottom of the tower at a rate of 4.639 tons / hour 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 production of dimethyl carbonate per hour, after deducting the dimethyl carbonate contained in the raw materials, was 4.920 tons, and the actual production of ethylene glycol per hour, after deducting the ethylene glycol contained 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 more, and the selectivity of ethylene glycol was 99.99% or more.

[0174] Under this condition, long-term continuous operation was carried out. After 500 hours, 2000 hours, 4000 hours, 5000 hours and 6000 hours of continuous operation, the actual production of dimethyl carbonate per hour was 4.630 tons, 4.828 tons, 4.639 tons, 4.635 tons and 4.728 tons, respectively; the actual production of ethylene glycol per hour was 3.222 tons, 3.283 tons, 3.265 tons, 3.226 tons and 3.232 tons, respectively; and the actual production of ethylene carbonate per hour was 3.667 tons, 3.656 tons, 3.640 tons and 3.697 tons, respectively. The reaction rates of esters are 99.99%, 99.99%, 99.99%, 99.99% and 99.99% respectively; the selectivities of dimethyl carbonate are above 99.99%, above 99.99%, above 99.99%, above 99.99% and above 99.99% respectively; and the selectivities of ethylene glycol are above 99.99%, above 99.99%, above 99.99%, above 99.99% and above 99.99% respectively.

[0175] [Example 3]

[0176] Continuous multi-stage distillation column

[0177] The same continuous multi-stage distillation column as in Example 1 was used, the tray structure was set to the same state as in Example 1 as described below, and reactive distillation was carried out by changing the amount of raw materials introduced into the distillation column.

[0178] On each upper tray, the effective area ratio is 45%, and the open area ratio is 4.5%. On each middle tray, the effective area ratio is 45%, and the open area ratio is 3.5%. On each lower tray, the effective area ratio is 45%, and the open area ratio is 3.0%.

[0179] exist Figure 1 In the continuous multi-stage distillation column shown, liquid ethylene carbonate was continuously introduced into the distillation column at a flow rate of 8.68 tons / hour from an inlet (3-a) provided on the fifth stage from the top of the distillation column. Gaseous methanol (containing 8.8% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 8.53 tons / hour from an inlet (3-b) provided on the 30th stage from the top of the distillation column. Liquid methanol (containing 6.5% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 19.74 tons / hour from an inlet (3-c) provided on the 30th stage from the top of the distillation column.

[0180] <Reactive distillation>

[0181] Reactive distillation was continuously performed under the same conditions as in Example 1 except for the conditions described below.

[0182] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) provided at the 54th layer from the bottom of the distillation column (catalyst concentration (calculated as alkali metal concentration): 0.6% by mass relative to the ethylene carbonate supplied). 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 5 Reactive distillation was continuously carried out under the conditions of 5% Pa and a reflux ratio of 0.45.

[0183] In the upper layer of the tower during reactive distillation, the gas flow rate is in the range of 36,260 kg / hour to 42,550 kg / hour, and the liquid flow rate is in the range of 11,100 kg / hour to 14,250 kg / hour; in the middle layer, the gas flow rate is in the range of 17,110 kg / hour to 29,600 kg / hour, and the liquid flow rate is in the range of 10,730 kg / hour to 12,030 kg / hour; in the lower layer, the gas flow rate is in the range of 9,770 kg / hour to 18,500 kg / hour, and the liquid flow rate is in the range of 14,760 kg / hour to 27,570 kg / hour.

[0184] After 24 hours, stable, steady-state operation was achieved. The low-boiling-point reaction mixture, extracted in a gaseous state from the gas extraction port 1 at the top of the tower, was cooled in a heat exchanger and converted to a liquid. The proportion of dimethyl carbonate in the liquid low-boiling-point reaction mixture, continuously extracted from the distillation tower at a rate of 28.205 tons / hour, was 9.774 tons / hour, and the proportion of methanol was 15.594 tons / hour. The proportion of ethylene glycol in the liquid continuously extracted from the liquid extraction port 2 at the bottom of the tower at a rate of 9.034 tons / hour 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 production of dimethyl carbonate per hour, after deducting the dimethyl carbonate contained in the raw materials, was 8.604 tons, and the actual production of ethylene glycol per hour, after deducting the ethylene glycol contained 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 more, and the selectivity of ethylene glycol was 99.99% or more.

[0185] Under this condition, long-term continuous operation was carried out. After 500 hours, 2000 hours, 4000 hours, 5000 hours and 6000 hours of continuous operation, the actual production of dimethyl carbonate per hour was 8.604 tons, 8.604 tons, 8.604 tons, 8.604 tons and 8.604 tons respectively, the actual production of ethylene glycol per hour was 5.467 tons, 5.467 tons, 5.467 tons, 5.467 tons and 5.467 tons respectively, and the actual production of ethylene carbonate per hour was 5.467 tons, 5.467 tons, 5.467 tons and 5.467 tons respectively. The reaction rates of esters are 99.99%, 99.99%, 99.99%, 99.99% and 99.99% respectively; the selectivities of dimethyl carbonate are above 99.99%, above 99.99%, above 99.99%, above 99.99% and above 99.99% respectively; and the selectivities of ethylene glycol are above 99.99%, above 99.99%, above 99.99%, above 99.99% and above 99.99% respectively.

[0186] [Comparative Example 1]

[0187] Continuous multi-stage distillation column

[0188] Reactive distillation was conducted using the same continuous multi-stage distillation column as in Example 1, with the tray configuration modified as follows. On each upper tray, the effective area ratio was 38%, and the open area ratio was 4.5%. On each middle tray, the effective area ratio was 38%, and the open area ratio was 4.5%. On each lower tray, the effective area ratio was 38%, and the open area ratio was 4.8%.

[0189] <Reactive distillation>

[0190] Reactive distillation was continuously performed under the same conditions as in Example 1 except for the conditions described below.

[0191] exist Figure 1 In the continuous multi-stage distillation column shown, liquid ethylene carbonate was continuously introduced into the distillation column at a flow rate of 7.546 tons / hour from an inlet (3-a) provided on the fifth stage from the top of the distillation column. Gaseous methanol (containing 8.8% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 7.742 tons / hour from an inlet (3-b) provided on the 30th stage from the top of the distillation column. Liquid methanol (containing 6.5% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 17.282 tons / hour from an inlet (3-c) provided on the 30th stage from the top of the distillation column.

[0192] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) provided at the 54th layer from the bottom of the distillation column (catalyst concentration (calculated as alkali metal concentration): 0.6% by mass relative to the supplied ethylene carbonate).

[0193] The temperature at the bottom of the tower is 98°C and the pressure at the top of the tower is about 1.118×10 5 Reactive distillation was carried out continuously under the conditions of Pa and a reflux ratio of 0.45.

[0194] In the upper layer of the tower during reactive distillation, the gas flow rate is in the range of 31523 kg / hour to 36991 kg / hour, and the liquid flow rate is in the range of 9906 kg / hour to 12384 kg / hour; in the middle layer, the gas flow rate is in the range of 15272 kg / hour to 25733 kg / hour, and the liquid flow rate is in the range of 9575 kg / hour to 10454 kg / hour; in the lower layer, the gas flow rate is in the range of 8717 kg / hour to 16083 kg / hour, and the liquid flow rate is in the range of 13174 kg / hour to 23964 kg / hour.

[0195] After 24 hours, stable, steady-state operation was achieved. The low-boiling-point reaction mixture, extracted in a gaseous state from the gas extraction port 1 at the top of the tower, was cooled in a heat exchanger and converted to a liquid. The proportion of dimethyl carbonate in the liquid low-boiling-point reaction mixture, continuously extracted from the distillation tower at a rate of 24.642 tons / hour, was 4.109 tons / hour, and the proportion of methanol was 15.115 tons / hour. The proportion of ethylene glycol in the liquid continuously extracted from the liquid extraction port 2 at the bottom of the tower at a rate of 7.804 tons / hour 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 production of dimethyl carbonate per hour, after deducting the dimethyl carbonate contained in the raw materials, was 7.708 tons, and the actual production of ethylene glycol per hour, after deducting the ethylene glycol contained 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 more, and the selectivity of ethylene glycol was 99.99% or more.

[0196] Under this condition, long-term continuous operation was carried out. After 500 hours, 2000 hours, 4000 hours, 5000 hours and 6000 hours of continuous operation, the actual production of dimethyl carbonate per hour was 7.708 tons, 7.708 tons, 7.706 tons, 7.706 tons and 7.708 tons, respectively, and the actual production of ethylene glycol per hour was 5.310 tons, 5.312 tons, 5.310 tons and 5.310 tons, respectively. and 5.310 tons, the reaction rates of ethylene carbonate were 99.7%, 99.7%, 99.7%, 99.7% and 99.7% respectively, the selectivities of dimethyl carbonate were 99.99%, 99.99%, 99.99%, 99.99% and 99.99% respectively, and the selectivities of ethylene glycol were 99.99%, 99.99%, 99.99%, 99.99% and 99.99% respectively.

[0197] [Comparative Example 2]

[0198] Continuous multi-stage distillation column

[0199] Except for the conditions described below, reactive distillation was continuously carried out under the same conditions as in Example 1. The same amount of raw materials as in Example 3 was continuously introduced into the distillation column.

[0200] Regarding the tray structure of the continuous multi-stage distillation column, the effective area ratio of each upper tray is 82%, and the open area ratio is 4.9%. Furthermore, the effective area ratio of each middle tray is 82%, and the open area ratio is 4.9%. Furthermore, the effective area ratio of each lower tray is 85%, and the open area ratio is 3.3%.

[0201] exist Figure 1 In the continuous multi-stage distillation column shown, liquid ethylene carbonate was continuously introduced into the distillation column at a flow rate of 8.68 tons / hour from an inlet (3-a) provided on the fifth stage from the top of the distillation column. Gaseous methanol (containing 8.8% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 8.53 tons / hour from an inlet (3-b) provided on the 30th stage from the top of the distillation column. Liquid methanol (containing 6.5% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 19.74 tons / hour from an inlet (3-c) provided on the 30th stage from the top of the distillation column.

[0202] <Reactive distillation>

[0203] Reactive distillation was continuously carried out under the same conditions as in Example 3.

[0204] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) provided at the 54th layer from the bottom of the distillation column (catalyst concentration (calculated as alkali metal concentration): 0.6% by mass relative to the ethylene carbonate supplied). 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 5 Reactive distillation was continuously carried out under the conditions of 5% Pa and a reflux ratio of 0.45.

[0205] In the upper layer of the tower during reactive distillation, the gas flow rate is in the range of 33,250 kg / hour to 40,200 kg / hour, and the liquid flow rate is in the range of 12,520 kg / hour to 40,200 kg / hour; in the middle layer, the gas flow rate is in the range of 15,420 kg / hour to 25,200 kg / hour, and the liquid flow rate is in the range of 12,320 kg / hour to 14,250 kg / hour; in the lower layer, the gas flow rate is in the range of 8,270 kg / hour to 14,200 kg / hour, and the liquid flow rate is in the range of 13,750 kg / hour to 24,450 kg / hour.

[0206] After 24 hours, stable, steady-state operation was achieved. The low-boiling-point reaction mixture, extracted in a gaseous state from the gas extraction port 1 at the top of the tower, was cooled in a heat exchanger and converted to a liquid. The proportion of dimethyl carbonate in the liquid low-boiling-point reaction mixture, continuously extracted from the distillation tower at a rate of 28.036 tons / hour, was 9.715 tons / hour, and the proportion of methanol was 15.500 tons / hour. The proportion of ethylene glycol in the liquid continuously extracted from the liquid extraction port 2 at the bottom of the tower at a rate of 8.979 tons / hour 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 production of dimethyl carbonate per hour, after deducting the dimethyl carbonate contained in the raw materials, was 8.543 tons, and the actual production of ethylene glycol per hour, after deducting the ethylene glycol contained 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%.

[0207] Under these conditions, long-term continuous operation was carried out. After 500 hours, 1000 hours, and 2000 hours of this continuous operation, the actual production of dimethyl carbonate per hour was 8.547 tons, 8.547 tons, and 8.546 tons respectively, the actual production of ethylene glycol per hour was 5.431 tons, 5.430 tons, and 5.431 tons respectively, the reaction rate of ethylene carbonate was 99.33%, 99.33%, and 99.32% respectively, 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.

[0208] [Comparative Example 3]

[0209] Continuous multi-stage distillation column

[0210] Except for the conditions described below, reactive distillation was continuously performed under the same conditions as in Example 1. The same amount of raw materials as in Comparative Example 1 was continuously introduced into the distillation column.

[0211] Regarding the tray structure of the continuous multi-stage distillation column, the effective area ratio of each upper tray is 82%, and the open area ratio is 4.9%. Furthermore, the effective area ratio of each middle tray is 82%, and the open area ratio is 4.9%. Furthermore, the effective area ratio of each lower tray is 85%, and the open area ratio is 3.3%.

[0212] exist Figure 1 In the continuous multi-stage distillation column shown, liquid ethylene carbonate was continuously introduced into the distillation column at a flow rate of 7.546 tons / hour from an inlet (3-a) provided on the fifth stage from the top of the distillation column. Gaseous methanol (containing 8.8% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 7.742 tons / hour from an inlet (3-b) provided on the 30th stage from the top of the distillation column. Liquid methanol (containing 6.5% by mass of dimethyl carbonate) was continuously introduced into the distillation column at a flow rate of 17.282 tons / hour from an inlet (3-c) provided on the 30th stage from the top of the distillation column.

[0213] <Reactive distillation>

[0214] Reactive distillation was continuously performed under the same conditions as in Comparative Example 1.

[0215] The catalyst was synthesized in the same manner as in Example 1 and continuously introduced into the distillation column from an inlet (3-e) provided at the 54th layer from the bottom of the distillation column (catalyst concentration (calculated as alkali metal concentration): 0.6% by mass relative to the ethylene carbonate supplied). 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 5 Reactive distillation was carried out continuously under the conditions of Pa and a reflux ratio of 0.45.

[0216] In the upper layer of the tower during reactive distillation, the gas flow rate is in the range of 31544kg / hour to 36975kg / hour, and the liquid flow rate is in the range of 9912kg / hour to 12348kg / hour; in the middle layer, the gas flow rate is in the range of 15274kg / hour to 25733kg / hour, and the liquid flow rate is in the range of 9572kg / hour to 10448kg / hour; in the lower layer, the gas flow rate is in the range of 8720kg / hour to 16078kg / hour, and the liquid flow rate is in the range of 13180kg / hour to 23928kg / hour.

[0217] After 24 hours, stable, steady-state operation was achieved. The low-boiling-point reaction mixture, extracted in a gaseous state from the gas extraction port 1 at the top of the tower, was cooled in a heat exchanger and converted to a liquid. The proportion of dimethyl carbonate in the liquid low-boiling-point reaction mixture, continuously extracted from the distillation tower at a rate of 26.669 tons / hour, was 4.113 tons / hour, and the proportion of methanol was 15.130 tons / hour. The proportion of ethylene glycol in the liquid continuously extracted from the liquid extraction port 2 at the bottom of the tower at a rate of 7.796 tons / hour 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 production of dimethyl carbonate per hour, after deducting the dimethyl carbonate contained in the raw materials, was 7.716 tons, and the actual production of ethylene glycol per hour, after deducting the ethylene glycol contained 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%.

[0218] Under these conditions, long-term continuous operation was carried out. After 500 hours, 1000 hours, and 2000 hours of this continuous operation, the actual production of dimethyl carbonate per hour was 7.716 tons, 7.716 tons, and 7.716 tons, respectively, and the actual production of ethylene glycol per hour was 5.315 tons, 5.315 tons, and 5.315 tons, respectively. The reaction rate of ethylene carbonate was 99.80%, 99.80%, and 99.80%, respectively, 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.

[0219] This application is based on the Japanese patent application (Japanese Patent Application No. 2021-002028) filed on January 8, 2021, the contents of which are incorporated into this application by reference.

[0220] Industrial Applicability

[0221] According to the present invention, dialkyl carbonate and diols can be produced from cyclic carbonate and aliphatic monohydric alcohols at a high selectivity of 97% or more, preferably 99% or more, and more preferably 99.99% or more, respectively, to dialkyl carbonate and diols, and at an industrial scale of 4.5 tons or more, preferably 5 tons or more, and more preferably 5.2 tons or more of dialkyl carbonate per hour, and 2.5 tons or more, preferably 3.0 tons or more, and more preferably 3.2 tons or more of diols per hour, and stably and long-term for 1000 hours or more, preferably 3000 hours or more, and more preferably 5000 hours or more, with high yields, thus having industrial applicability. It should be noted that the upper limit of the production of dialkyl carbonate is not particularly limited, for example, it is 12 tons or less per hour, and the upper limit of the production of diols is not particularly limited, for example, it is 8 tons or less per hour.

[0222] Description of labels

[0223] 1: Gas extraction port, 2: Liquid extraction port, 3-a to 3-e: Inlet, 4-a to 4-b: Inlet, 5: End plate, 6: Internal component, 7: Tower body, 10: Continuous multi-stage distillation tower, L: Tower body length (cm), D: Tower body inner diameter (cm), d1: Inner diameter of gas extraction port (cm), d2: Inner diameter of liquid extraction port (cm), 11: Downcomer, 12: Effective area, 13: Plate platform, 14: One of the holes (the part represented by 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 the holes.

Claims

1. A method for industrially producing dialkyl carbonates and diols, wherein: In the case of continuously producing dialkyl carbonates and diols by a reactive distillation method in which a cyclic carbonate and an aliphatic monohydric alcohol are used as raw materials, the raw materials are continuously supplied to a continuous multi-stage distillation column in the presence of a homogeneous catalyst, reaction and distillation are simultaneously carried out in the column, a low-boiling-point reaction mixture containing the produced dialkyl carbonate is continuously withdrawn in a gaseous state from the upper part of the column, and a high-boiling-point reaction mixture containing the diols is continuously withdrawn in a liquid state from the lower part of the column, (a) The continuous multi-stage distillation column is a tray-type distillation column having a cylindrical column body having a length L (cm) and an inner diameter D (cm) and an internal member therein, wherein the internal member is a tray having a plurality of holes, and the column has a gas extraction port at or near the top of the column, a liquid extraction port at or near the bottom of the column, one or more first inlets below the gas extraction port and in the upper and / or middle portion of the column, and one or more second inlets above the liquid extraction port and in the middle and / or lower portion of the column. (1) The length of the tower L (cm) satisfies formula (1), 1,500≤L≤12,000 Formula (1) (2) The inner diameter D (cm) of the tower satisfies formula (2), 120≤D≤3,000 Formula (2) (3) The internal components include three types of trays: upper, middle and lower. (4) continuously introducing the cyclic carbonate as a raw material into the continuous multi-stage distillation column from one or more first inlets, wherein the upper layer is a layer above the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the upper layer to the total number of trays is 1% to 10%, (5) an aliphatic monohydric alcohol as a raw material is continuously introduced into the continuous multi-stage distillation column from one or more second inlets, the middle stage is a layer from the layer of the uppermost inlet among the one or more second inlets to the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the middle stage to the total number of trays is 40% to 50%, (6) The lower layer is a layer below the layer of the uppermost inlet among the one or more second inlets, and the number of trays in the lower layer accounts for 45% to 55% of the total number of trays. (7) In each lower tray, the ratio of the effective area calculated by the following formula (i) is 40% to 80%, and the ratio of the open area calculated by the following formula (ii) is 1.0% to 5.0%, Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i) In formula (i), the effective area refers to the area of ​​the partition with holes in the tray landing portion, that is, the area of ​​the range extending 4 inches outward from the boundary of the minimum area containing all holes. The tray area refers to the area of ​​the tray landing portion. The tray area is the area including the effective area but excluding the downcomer portion. Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii) In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i). (8) In each of the upper and middle trays, the ratio of the effective area calculated by the above formula (i) is 40% to 80%, and the ratio of the open area calculated by the above formula (ii) is 1.0 times or more the ratio of the open area calculated by the above formula (ii) in each of the lower trays, (9) The homogeneous catalyst comprises a mixture of an alkali metal and ethylene glycol, wherein the mass ratio of the alkali metal to the ethylene glycol in the homogeneous catalyst (alkali metal / ethylene glycol) is 0.05 to 0.5, and the catalyst concentration, calculated as the alkali metal concentration, is 0.05% by mass to 2.0% by mass relative to the cyclic carbonate supplied to the distillation column.

2. The method according to claim 1, wherein 2,200≤L≤10,000。 3. The method according to claim 1 or 2, wherein: 2,500≤L≤5,000。 4. The method according to claim 1 or 2, wherein: 150≤D≤2,000。 5. The method according to claim 1 or 2, wherein: 180≤D≤1,200。 6. The method according to claim 1 or 2, wherein: 210≤D≤800。 7. The method according to claim 1 or 2, wherein: The total number of floors of the upper, middle and lower floors is 10 to 100.

8. The method according to claim 7, wherein: The total number of floors of the upper, middle and lower floors is 30 to 100.

9. The method according to claim 7, wherein: The total number of floors of the upper, middle and lower floors is 30 to 80.

10. The method according to claim 1 or 2, wherein: The ratio of the number of upper trays to the total number of trays is 3% to 10%.

11. The method according to claim 1 or 2, wherein: The ratio of the number of upper trays to the total number of trays is 5% to 10%.

12. The method according to claim 1 or 2, wherein: The proportion of the number of trays in the middle stage is 40% to 45% of the total number of stages.

13. The method according to claim 1 or 2, wherein: The proportion of the number of trays in the middle stage is 40% to 43% of the total number of stages.

14. The method according to claim 1 or 2, wherein: The ratio of the number of trays in the lower stage to the total number of stages is 48% to 55%.

15. The method according to claim 1 or 2, wherein: The ratio of the number of trays in the lower stage to the total number of stages is 50% to 55%.

16. The method according to claim 1 or 2, wherein: In each lower tray, the ratio of the effective area calculated by formula (i) is 40% to 70%.

17. The method according to claim 1 or 2, wherein: In each lower tray, the ratio of the effective area calculated by formula (i) is 45% to 65%.

18. The method according to claim 1 or 2, wherein: In each lower tray, the ratio of the effective area calculated by formula (i) is 45% to 55%.

19. The method according to claim 1 or 2, wherein: In each lower tray, the ratio of the open area calculated by formula (ii) is 1.0% to 4.0%.

20. The method according to claim 1 or 2, wherein: In each lower tray, the ratio of the open area calculated by formula (ii) is 1.0% to 3.5%.

21. The method according to claim 1 or 2, wherein: In each lower tray, the ratio of the open area calculated by formula (ii) is 2.0% to 3.5%.

22. The method according to claim 1 or 2, wherein: In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 40% to 70%.

23. The method according to claim 1 or 2, wherein In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 40% to 65%.

24. The method according to claim 1 or 2, wherein: In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 45% to 65%.

25. The method according to claim 1 or 2, wherein In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 45% to 55%.

26. The method according to claim 1 or 2, wherein In each of the upper and middle trays, the ratio of the open area calculated by formula (ii) is 1.0 to 6.0 times the ratio of the open area calculated by formula (ii) in each of the lower trays.

27. The method according to claim 1 or 2, wherein In each of the upper and middle trays, the ratio of the open area calculated by formula (ii) is 1.0 to 3.0 times the ratio of the open area calculated by formula (ii) in each of the lower trays.

28. The method according to claim 1 or 2, wherein In each of the upper and middle trays, the ratio of the open area calculated by formula (ii) is 1.0 to 1.5 times the ratio of the open area calculated by formula (ii) in each of the lower trays.

29. The method according to claim 1 or 2, wherein The mass ratio of alkali metal to ethylene glycol (alkali metal / ethylene glycol) in the homogeneous catalyst is 0.1 to 0.

4.

30. The method according to claim 1 or 2, wherein The mass ratio of alkali metal to ethylene glycol (alkali metal / ethylene glycol) in the homogeneous catalyst is 0.2 to 0.

3.

31. The method according to claim 1 or 2, wherein The catalyst concentration calculated as the alkali metal concentration is 0.1% by mass to 1.0% by mass relative to the cyclic carbonate supplied to the distillation column.

32. The method according to claim 1 or 2, wherein The catalyst concentration calculated as alkali metal concentration is 0.5% by mass to 1.0% by mass relative to the cyclic carbonate supplied to the distillation column.

33. The method according to claim 1 or 2, wherein The alkali metal is lithium, potassium, sodium or cesium.

34. The method according to claim 1 or 2, wherein The molar ratio of the aliphatic monohydric alcohol to the cyclic carbonate is 2 to 20.

35. The method according to claim 34, wherein The molar ratio of the aliphatic monohydric alcohol to the cyclic carbonate is 3 to 15.

36. The method of claim 34, wherein: The molar ratio of the aliphatic monohydric alcohol to the cyclic carbonate is 5 to 12.

37. The method according to claim 1 or 2, wherein In the upper layer, 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.

38. The method according to claim 1 or 2, wherein In the middle layer, 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.

39. The method according to claim 1 or 2, wherein In the lower layer, 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.

40. The method according to claim 1 or 2, wherein In the upper layer, 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. In the middle layer, 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. In the lower layer, 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.

41. The method according to claim 40, wherein In the upper layer, the gas flow rate is 10,000 kg / hour to 25,000 kg / hour.

42. The method of claim 40, wherein: In the upper layer, the gas flow rate is 15,000 kg / hour to 25,000 kg / hour.

43. The method of claim 40, wherein: In the upper layer, the liquid flow rate is 3,000 kg / hour to 10,000 kg / hour.

44. The method of claim 40, wherein In the upper layer, the liquid flow rate is 4,000 kg / hour to 8,000 kg / hour.

45. The method of claim 40, wherein In the middle layer, the gas flow rate is 10,000 kg / hour to 25,000 kg / hour.

46. ​​The method of claim 40, wherein In the middle layer, the gas flow rate is 10,000 kg / hour to 20,000 kg / hour.

47. The method of claim 40, wherein: In the middle layer, the liquid flow rate is 3,000 kg / hour to 10,000 kg / hour.

48. The method of claim 40, wherein In the middle layer, the liquid flow rate is 3,000 kg / hour to 8,000 kg / hour.

49. The method of claim 40, wherein In the lower layer, the gas flow rate is 5,000 kg / hour to 10,000 kg / hour.

50. The method of claim 40, wherein In the lower layer, the liquid flow rate is 5,000 kg / hour to 20,000 kg / hour.

51. The method of claim 40, wherein: In the lower layer, the liquid flow rate is 5,000 kg / hour to 15,000 kg / hour.

52. The method according to claim 1 or 2, wherein The amount of dialkyl carbonate produced was 4.5 tons or more per hour.

53. The method of claim 52, wherein: The amount of dialkyl carbonate produced is 5 tons or more per hour.

54. The method of claim 52, wherein The amount of dialkyl carbonate produced was 5.2 tons or more per hour.

55. The method of claim 52, wherein: The amount of dialkyl carbonate produced was 12 tons or less per hour.

56. The method according to claim 1 or 2, wherein The amount of diols produced is 2.5 tons or more per hour.

57. The method of claim 56, wherein The amount of diols produced is 3.0 tons or more per hour.

58. The method of claim 56, wherein The amount of diols produced was 3.2 tons or more per hour.

59. The method of claim 56, wherein The amount of diols produced was 8 tons or less per hour.

60. The method according to claim 1 or 2, wherein The cyclic carbonate is represented by the following formula (A), In formula (A), R l Represents a divalent group -(CH2) m -, m is an integer of 2 to 6, and one or more hydrogen atoms therein may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms.

61. The method of claim 60, wherein: The cyclic carbonate is ethylene carbonate or propylene carbonate.

62. The method according to claim 1 or 2, wherein The aliphatic monohydric alcohol is represented by the following formula (B), R 2 OH (B) In formula (B), R 2 It represents a monovalent aliphatic group having 1 to 12 carbon atoms, in which one or more hydrogen atoms may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms.

63. The method of claim 62, wherein: The aliphatic monohydric alcohol is methanol, ethanol, propanol, allyl alcohol, butanol, 3-butene-1-ol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, methylcyclopentanol, ethylcyclopentanol, methylcyclohexanol, ethylcyclohexanol, dimethylcyclohexanol, diethylcyclohexanol, phenylcyclohexanol, benzyl alcohol, phenylethyl alcohol or phenylpropanol.

64. The method according to claim 1 or 2, wherein The dialkyl carbonate is represented by the following formula (C), In formula (C), R 2 It represents a monovalent aliphatic group having 1 to 12 carbon atoms, in which one or more hydrogen atoms may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms.

65. The method of claim 64, wherein The dialkyl carbonate is dimethyl carbonate.

66. The method according to claim 1 or 2, wherein The diols are represented by the following formula (D): In formula (D), R l Represents a divalent group -(CH2) m -, m is an integer of 2 to 6, and one or more hydrogen atoms therein may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms.

67. The method of claim 66, wherein The diol is ethylene glycol.

68. The method according to claim 1 or 2, wherein The cyclic carbonate is produced by reacting an alkylene oxide with carbon dioxide.

69. The method of claim 68, wherein The alkylene oxide is ethylene oxide, propylene oxide or phenylethylene oxide.

70. A continuous multi-stage distillation tower for carrying out transesterification reaction and distillation of a cyclic carbonate and an aliphatic monohydric alcohol, wherein: (a) The continuous multi-stage distillation column comprises: a cylindrical column body having a length L (cm) and an inner diameter D (cm); a tray having a plurality of holes disposed inside the column body as an internal member; a gas extraction port located at or near the top of the column in an upper portion of the column; a liquid extraction port located at or near the bottom of the column in a lower portion of the column; one or more first inlets located below the gas extraction port and in an upper portion and / or middle portion of the column; and one or more second inlets located above the liquid extraction port and in an upper portion and / or lower portion of the column. (1) The length of the tower L (cm) satisfies formula (1), 1,500≤L≤12,000 Formula (1) (2) The inner diameter D (cm) of the tower satisfies formula (2), 120≤D≤3,000 Formula (2) (3) The internal components include three types of trays: upper, middle and lower. (4) continuously introducing the cyclic carbonate as a raw material into the continuous multi-stage distillation column from one or more first inlets, wherein the upper layer is a layer above the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the upper layer to the total number of trays is 1% to 10%, (5) an aliphatic monohydric alcohol as a raw material is continuously introduced into the continuous multi-stage distillation column from one or more second inlets, the middle stage is a layer from the layer of the uppermost inlet among the one or more second inlets to the layer of the uppermost inlet among the one or more first inlets, and the proportion of the number of trays in the middle stage to the total number of trays is 40% to 50%, (6) the lower layer is a layer below the layer of the uppermost inlet among the one or more second inlets, and the ratio of the number of trays in the lower layer to the total number of trays is 45% to 55%, (7) In each lower tray, the ratio of the effective area calculated by the following formula (i) is 40% to 80%, and the ratio of the open area calculated by the following formula (ii) is 1.0% to 5.0%, Effective area ratio (%) = effective area (cm 2 ) / tray area (cm 2 )×100……(i) In formula (i), the effective area refers to the area of ​​the partition with holes in the tray landing portion, that is, the area of ​​the range extending 4 inches outward from the boundary of the minimum area containing all holes. The tray area refers to the area of ​​the tray landing portion. The tray area is the area including the effective area but excluding the downcomer portion. Open area ratio (%) = open area area (cm 2 ) / effective area (cm 2 )×100……(ii) In formula (ii), the open area refers to the total area of ​​all holes in the effective area, and the meaning of the effective area is the same as that of formula (i). (8) In each of the upper and middle trays, the ratio of the effective area calculated by the above formula (i) is 40% to 80%, and the ratio of the open area calculated by the above formula (ii) is 1.0 times or more of the ratio of the open area calculated by the above formula (ii) in each of the lower trays.

71. The continuous multi-stage distillation column according to claim 70, wherein 2,200≤L≤10,000。 72. The continuous multi-stage distillation column according to claim 70 or 71, wherein 2,500≤L≤5,000。 73. The continuous multi-stage distillation column according to claim 70 or 71, wherein 150≤D≤2,000。 74. The continuous multi-stage distillation column according to claim 70 or 71, wherein 180≤D≤1,200。 75. The continuous multi-stage distillation column according to claim 70 or 71, wherein 210≤D≤800。 76. The continuous multi-stage distillation column according to claim 70 or 71, wherein The total number of floors of the upper, middle and lower floors is 10 to 100.

77. The continuous multi-stage distillation column according to claim 76, wherein The total number of floors of the upper, middle and lower floors is 30 to 100.

78. The continuous multi-stage distillation column according to claim 76, wherein The total number of floors of the upper, middle and lower floors is 30 to 80.

79. The continuous multi-stage distillation column according to claim 70 or 71, wherein The ratio of the number of upper trays to the total number of trays is 3% to 10%.

80. The continuous multi-stage distillation column according to claim 70 or 71, wherein The ratio of the number of upper trays to the total number of trays is 5% to 10%.

81. The continuous multi-stage distillation column according to claim 70 or 71, wherein The proportion of the number of trays in the middle stage is 40% to 45% of the total number of stages.

82. The continuous multi-stage distillation column according to claim 70 or 71, wherein The proportion of the number of trays in the middle stage is 40% to 43% of the total number of stages.

83. The continuous multi-stage distillation column according to claim 70 or 71, wherein The ratio of the number of trays in the lower stage to the total number of stages is 48% to 55%.

84. The continuous multi-stage distillation column according to claim 70 or 71, wherein The ratio of the number of trays in the lower stage to the total number of stages is 50% to 55%.

85. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each lower tray, the ratio of the effective area calculated by formula (i) is 40% to 70%.

86. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each lower tray, the ratio of the effective area calculated by formula (i) is 45% to 65%.

87. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each lower tray, the ratio of the effective area calculated by formula (i) is 45% to 55%.

88. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each lower tray, the ratio of the open area calculated by formula (ii) is 1.0% to 4.0%.

89. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each lower tray, the ratio of the open area calculated by formula (ii) is 1.0% to 3.5%.

90. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each lower tray, the ratio of the open area calculated by formula (ii) is 2.0% to 3.5%.

91. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 40% to 70%.

92. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 40% to 65%.

93. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 45% to 65%.

94. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the effective area calculated by formula (i) is 45% to 55%.

95. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the open area calculated by formula (ii) is 1.0 to 6.0 times the ratio of the open area calculated by formula (ii) in each of the lower trays.

96. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the open area calculated by formula (ii) is 1.0 to 3.0 times the ratio of the open area calculated by formula (ii) in each of the lower trays.

97. The continuous multi-stage distillation column according to claim 70 or 71, wherein In each of the upper and middle trays, the ratio of the open area calculated by formula (ii) is 1.0 to 1.5 times the ratio of the open area calculated by formula (ii) in each of the lower trays.

98. The continuous multi-stage distillation column according to claim 70 or 71, wherein The cyclic carbonate is represented by the following formula (A), In formula (A), R l Represents a divalent group -(CH2) m -, m is an integer of 2 to 6, and one or more hydrogen atoms therein may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms.

99. The continuous multi-stage distillation column according to claim 98, wherein The cyclic carbonate is ethylene carbonate or propylene carbonate.

100. The continuous multi-stage distillation column according to claim 70 or 71, wherein The aliphatic monohydric alcohol is represented by the following formula (B), R 2 OH (B) In formula (B), R 2 It represents a monovalent aliphatic group having 1 to 12 carbon atoms, in which one or more hydrogen atoms may be substituted by an alkyl group or an aryl group having 1 to 10 carbon atoms.

101. The continuous multi-stage distillation column according to claim 100, wherein The aliphatic monohydric alcohol is methanol, ethanol, propanol, allyl alcohol, butanol, 3-butene-1-ol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, methylcyclopentanol, ethylcyclopentanol, methylcyclohexanol, ethylcyclohexanol, dimethylcyclohexanol, diethylcyclohexanol, phenylcyclohexanol, benzyl alcohol, phenylethyl alcohol or phenylpropanol.

102. The continuous multi-stage distillation column according to claim 70 or 71, wherein The cyclic carbonate is produced by reacting an alkylene oxide with carbon dioxide.

103. The continuous multi-stage distillation column according to claim 102, wherein The alkylene oxide is ethylene oxide, propylene oxide or phenylethylene oxide.

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