Method for producing high purity diaryl carbonate

Abstract

A method for industrially producing a high-purity diaryl carbonate, the method comprising: a first refining step for continuously introducing a mixture containing a diaryl carbonate to a refining column A that has a side-cut discharge port and continuously separating, through distillation, the mixture into a column peak component (At), a side-cut component (As) including the diaryl carbonate, and a column bottom component (Ab) including a catalyst; and a second refining step for continuously introducing the side-cut component (As) to a diaryl carbonate refining column B that has a side-cut discharge port and continuously separating, through distillation, the component into three components which are a column peak component (Bt), a side-cut component (Bs), and a column bottom component (Bb) to obtain a high-purity diaryl carbonate as the side-cut component (Bs).

Description

[Technical field]

[0001] The present invention relates to a method for producing high purity diaryl carbonate. [Background technology]

[0002] For example, in order to produce aromatic polycarbonate by transesterification on an industrial scale, it is required to obtain high-purity diaryl carbonate in large quantities on an industrial scale. It is difficult to obtain high-purity diaryl carbonate in large quantities on an industrial scale, and it is desired to develop a useful method for producing high-purity diaryl carbonate. For example, the production methods shown in Patent Document 1 and Patent Document 2 are disclosed as high-purity diaryl carbonate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2006 / 025478 [Patent Document 2] International Publication No. 2007 / 072705 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional techniques, particularly the methods described in Patent Documents 1 and 2, using a conventional catalyst separation tower and diaryl carbonate purification tower, it is necessary to evaporate the alkylaryl carbonate twice, and a large amount of energy is required for purification and separation. In addition, the use of a large amount of energy causes deterioration of the alkylaryl carbonate or diaryl carbonate during purification, and there is a large amount of loss due to distillation, leaving room for improvement. Therefore, an object of the present invention is to provide a method for producing high-purity diaryl carbonate, which can reduce the amount of energy used in purification and the amount of loss due to distillation. [Means for solving the problem]

[0005] The present inventors have conducted extensive research to find a specific method for achieving the above object, and as a result, have arrived at the present invention.

[0006] [1] A method for continuously producing high purity diaryl carbonate, comprising the steps of: a first purification step in which a mixture containing a diaryl carbonate is continuously introduced into a purification column A having a side cut withdrawal port, and the mixture is continuously separated by distillation into a column top component (At), a side cut component (As) containing the diaryl carbonate, and a column bottom component (Ab) containing the catalyst; a second purification step in which the side cut component (As) is continuously introduced into a diaryl carbonate purification column B having a side cut withdrawal port and continuously separated by distillation into three components, namely a column top component (Bt), a side cut component (Bs) and a column bottom component (Bb), thereby obtaining a high-purity diaryl carbonate as the side cut component (Bs); The present invention relates to an industrial method for producing a high purity diaryl carbonate comprising the steps of: [2] The method according to [1], wherein the mixture contains diaryl carbonate in an amount of 40% by mass or more and 90% by mass or less. [3] The method according to [1] or [2], wherein the mixture contains alkyl aryl carbonate in an amount of 10% by mass or more and 50% by mass or less. [4] The manufacturing method according to any one of [1] to [3], wherein the content of diaryl carbonate in the side cut component (As) is 80 mass% or more, and the content of diaryl carbonate in the side cut component (Bs) is 99.1 mass% or more. [5] The method according to any one of [1] to [4], wherein the number of theoretical plates An from the bottom of the purification column A to the side cut outlet is in the range of 10 to 19. [6] The cross-sectional area of ​​purification column A (SA (m 2The manufacturing method according to any one of [1] to [5], wherein the ratio (SA / BsF) of the amount of raw material (sintered fines) extracted as the side cut component (Bs) to the amount of raw material (sintered fines) extracted as the side cut component (Bs) (BsF (tons / hour)) is in the range of 0.5 to 5. [7] The method according to any one of [1] to [6], wherein the ratio (DB1 / DB2) of the upper column diameter (DB1 (m)) to the lower column diameter (DB2 (m)) in purification column B is in the range of 0.1 or more and 0.9 or less. [8] The production method according to any one of [1] to [7], wherein the purification column A includes at least one reboiler selected from the group consisting of a forced circulation type, a cross-pipe falling film type, and a thin film evaporation type. [9] The packing of the purification column A and / or the purification column B is structured packing, The manufacturing method according to any one of [1] to [8], wherein the structured packing comprises at least one type selected from the group consisting of Melapack, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, Glitch grid and gauze packing.

[10] The method according to any one of [1] to [9], wherein the mixture is a reaction mixture obtained by at least one reaction selected from the group consisting of (i) a transesterification reaction between a dialkyl carbonate and an aryl alcohol, (ii) a disproportionation reaction of an alkylaryl carbonate, and (iii) a transesterification reaction between an alkylaryl carbonate and an aryl alcohol, in the presence of a catalyst.

[11] a step of continuously supplying a dialkyl carbonate and an aryl alcohol into a first continuous multi-stage distillation column in the presence of a catalyst, simultaneously carrying out reaction and distillation in the first continuous multi-stage distillation column, continuously withdrawing a first column low-boiling point reaction mixture containing the produced alcohol in a gaseous state from an upper portion of the first continuous multi-stage distillation column, and continuously withdrawing a first column high-boiling point reaction mixture containing the produced alkyl aryl carbonate in a liquid state from a lower portion of the first continuous multi-stage distillation column, thereby continuously producing an alkyl aryl carbonate; continuously supplying the first column high-boiling point reaction mixture into a second continuous multi-stage distillation column in the presence of a catalyst, and simultaneously carrying out reaction and distillation in the second continuous multi-stage distillation column, continuously withdrawing the second column low-boiling point reaction mixture containing the produced dialkyl carbonates in a gaseous state from an upper portion of the second continuous multi-stage distillation column, and continuously withdrawing the second column high-boiling point reaction mixture containing the produced diaryl carbonate in a liquid state from a lower portion of the second continuous multi-stage distillation column, thereby continuously producing diaryl carbonate, The method according to any one of [1] to

[10] , wherein the mixture is a second column high-boiling reaction mixture containing a diaryl carbonate.

[12] The method according to any one of [1] to

[11] , wherein the diaryl carbonate is diphenyl carbonate. Effect of the Invention

[0007] According to the present invention, it is possible to provide a method for producing a high purity diaryl carbonate, which can reduce the amount of energy used in purification and the amount of loss due to distillation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of an apparatus in which a purification column A and a diphenyl carbonate purification column B used in the present invention are connected. [Diagram 2] FIG. 1 is a schematic diagram showing an example of an apparatus in which a purification column A and a diphenyl carbonate purification column B are connected in the prior art. [Diagram 3] 1 is a schematic diagram showing an example of a continuous multi-stage distillation column T0. An internal made of a perforated tray is installed inside the body. [Figure 4] 1 is a schematic diagram showing an example of a first continuous multi-stage distillation column, in which an internal is installed inside the body. [Diagram 5] FIG. 1 is a schematic diagram showing an example of a second continuous multi-stage distillation column. Inside the body, an internal consisting of structured packing in the upper part and a perforated tray in the lower part is installed. [Figure 6]FIG. 1 is a schematic diagram showing an example of an apparatus in which a first continuous multi-stage distillation column and a second continuous multi-stage distillation column are connected together. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings as necessary, but the present invention is not limited to this, and various modifications are possible without departing from the gist of the present invention. In addition, positional relationships such as up, down, left, and right in the drawings are based on the positional relationships shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0010] The industrial production method of high purity diaryl carbonate of this embodiment includes the steps of: A method for continuously producing high purity diaryl carbonate, comprising the steps of: a first purification step in which a mixture containing a diaryl carbonate is continuously introduced into a purification column A having a side cut withdrawal port, and the mixture is continuously separated by distillation into a column top component (At), a side cut component (As) containing the diaryl carbonate, and a column bottom component (Ab) containing the catalyst; a second purification step in which the side cut component (As) is continuously introduced into a diaryl carbonate purification column B having a side cut withdrawal port and continuously separated by distillation into three components, namely a column top component (Bt), a side cut component (Bs) and a column bottom component (Bb), thereby obtaining a high-purity diaryl carbonate as the side cut component (Bs); Includes.

[0011] The industrial production method of high purity diaryl carbonate of the present embodiment has the above-mentioned features, and thus has the effect of reducing the amount of energy used in purification and the amount of loss due to distillation. Although the mechanism by which such effects are achieved is not clear, the present inventors presume it as follows.

[0012] By providing a side cut outlet in purification column A, most of the alkylaryl carbonate can be separated in purification column A. This makes it possible to suppress the deterioration of alkylaryl carbonate and diaryl carbonate while reducing the load on diaryl carbonate purification column B. As a result, it is believed that the amount of loss of diaryl carbonate due to distillation can be reduced. In addition, by reducing the amount of diaryl carbonate loss, it is possible to reduce the disposal of deteriorated materials, and further, the amount of energy used relative to the amount of production can be reduced, which is believed to make it possible to reduce the environmental impact when producing high-purity diaryl carbonate.

[0013] Furthermore, according to the industrial production method of high purity diaryl carbonate of this embodiment, it is possible to reduce the amount of energy used in refining and to lower the concentration of altered substances (hereinafter also referred to as "XA") in diphenyl carbonate, thereby making it possible to prevent deterioration of the quality of diaryl carbonate due to altered substances.

[0014] In the industrial production method of high purity diaryl carbonate of this embodiment, the mixture introduced into purification column A preferably contains diaryl carbonate in an amount of 40% by mass or more and 90% by mass or less, more preferably 45% by mass or more and 85% by mass or less, and even more preferably 50% by mass or more and 80% by mass or less. When the diaryl carbonate content in the mixture introduced into purification column A is equal to or more than the lower limit, loss tends to be reduced, and when it is equal to or less than the upper limit, control failure tends to be prevented.

[0015] In the industrial production method of high purity diaryl carbonate of this embodiment, the mixture introduced into purification column A preferably contains alkylaryl carbonate in a proportion of 10% by mass to 50% by mass, more preferably 15% by mass to 45% by mass, and even more preferably 20% by mass to 40% by mass. If the content of alkylaryl carbonate in the mixture introduced into purification column A is equal to or more than the lower limit, poor control tends to be prevented, and if it is equal to or less than the upper limit, loss tends to be reduced.

[0016] In this embodiment, the composition of the mixture introduced into purification column A can be measured by the method described in the Examples below.

[0017] In the industrial production method of high purity diaryl carbonate of this embodiment, there is no particular limitation on the mixture introduced into the purification column A. Particularly preferred as the mixture, its production apparatus, and production method is diphenyl carbonate produced and purified by reacting ethylene carbonate, which has been produced and purified by reacting ethylene oxide with CO2, with methanol to produce and purify dimethyl carbonate, and purified phenol, by reactive distillation, and this is an ultra-high purity product that does not contain alkali metals / alkaline earth metals or chlorine. The manufacturing methods for these are not particularly limited, but may be described, for example, in WO 2004 / 105696, WO 2007 / 34669, WO 2007 / 60893, WO 2007 / 60984, WO 2007 / 69462, WO 2007 / 69513, WO 2007 / 69514, WO 2007 / 72728, WO 2005 / 123638, WO 2007 / 74692, WO 200 Reference can be made to WO 7 / 88782, WO 2006 / 1256, WO 2006 / 1257, WO 2006 / 6566, WO 2006 / 6568, WO 2006 / 6585, WO 2006 / 6588, WO 2006 / 41075, WO 2006 / 43491, WO 2007 / 69529, WO 2007 / 69531, WO 2007 / 72705, etc. Furthermore, a diphenyl carbonate mixture produced by reacting a dialkyl carbonate produced and purified by reacting an alcohol with CO2 with purified phenol is also suitable. The manufacturing methods thereof are not particularly limited, but reference can be made to, for example, International Publication No. WO 2005 / 783, International Publication No. WO 2007 / 114130, International Publication No. WO 2003 / 55840, International Publication No. WO 2011 / 105442, and International Publication No. WO 2006 / 67982.In addition, for example, the reaction mixture is preferably a reaction mixture obtained by at least one reaction selected from the group consisting of (i) transesterification reaction of dialkyl carbonate with aryl alcohol, (ii) disproportionation reaction of alkylaryl carbonate, and (iii) transesterification reaction of alkylaryl carbonate with aryl alcohol in the presence of a catalyst. When the mixture introduced into the purification column A is such a reaction mixture, there is a tendency to reduce losses and prevent poor control.

[0018] The industrial production method of high purity diaryl carbonate of this embodiment includes the steps of: a first purification step in which a mixture containing a diaryl carbonate is continuously introduced into a purification column A having a side cut withdrawal port, and the mixture is continuously separated by distillation into a column top component (At), a side cut component (As) containing the diaryl carbonate, and a column bottom component (Ab) containing the catalyst; and a second purification step of continuously introducing the side cut component (As) into a diaryl carbonate purification column B having a side cut withdrawal port and continuously separating it into three components, namely a top component (Bt), a side cut component (Bs) and a bottom component (Bb), to obtain a high-purity diaryl carbonate as the side cut component (Bs) (hereinafter, the first and second purification steps are collectively referred to as the "separation and purification steps").

[0019] The mixture containing diaryl carbonate is mainly composed of diaryl carbonate, but may also contain, for example, unreacted alkylaryl carbonate, a small amount of unreacted raw material, a small amount of high-boiling by-products and catalyst components. Therefore, a separation and purification step is carried out from the mixture containing diaryl carbonate in order to obtain high-purity diphenyl carbonate. In the separation and purification step, two distillation columns (purification column A with a side cut outlet, diaryl carbonate purification column B with a side cut outlet) are used, and in the purification column A, for example, unreacted alkylaryl carbonate, a small amount of unreacted raw material, a top component (At) mainly composed of diaryl carbonate, a side cut component (As) containing diaryl carbonate, and a bottom component (Ab) mainly composed of a small amount of high boiling by-products and / or catalyst components are continuously separated, and the side cut component (As) of the purification column is continuously fed to the diaryl carbonate purification column B, and in the diaryl carbonate purification column B, it is continuously separated into three components, the top component (Bt), the side cut component (Bs), and the bottom component (Bb), and a high purity diaryl carbonate can be obtained as the side cut component (Bs). By installing a side cut outlet in the purification column A, most of the alkylaryl carbonate can be separated in the purification column A. This makes it possible to suppress the deterioration of alkylaryl carbonate and diaryl carbonate while reducing the load on diaryl carbonate purification column B. As a result, it is believed that the amount of loss of diaryl carbonate due to distillation can be reduced. In addition, the reduction in the amount of diaryl carbonate loss makes it possible to reduce the disposal of deteriorated materials, and furthermore, the amount of energy used relative to the amount of production can be reduced, which is believed to make it possible to reduce the environmental load when producing high-purity diaryl carbonate.

[0020] In the separation and purification step, the purification column A has a length of, for example, L A (cm), inner diameter D AThe column has a cylindrical body of 1.2 cm and an internal structure. The column has an inlet A1 in the middle and a side cut outlet A2 between the inlet A1 and the column bottom. The number of stages of the internals from the inlet A1 to the top is n. A1 , the number of internal stages between the inlet A1 and the side cut outlet A2 is n A2 , the number of internal stages below the side cut outlet A2 is n A3 The total number of stages (n A1 +n A2 +n A3 ) is n A A continuous multi-stage distillation column having a L A , D A , n A1 , n A2 , n A3 , n A are preferably continuous multi-stage distillation columns satisfying the following formulas (19) to (24), respectively. 800 ≦ L A ≦ 3000 Formula (19) 100 ≦ D A ≦ 1000 formula (20) 1 ≦ n A1 ≦ 5 Equation (21) 10 ≦ n A2 ≦ 19 Equation (22) 10 ≦ n A ≦ 50 Equation (24)

[0021] In the industrial production method of high purity diaryl carbonate of this embodiment, in particular, the number of theoretical plates An from the bottom of the purification column A to the side cut outlet, i.e., n A2 is preferably in the range of 10 or more and 19 or less, more preferably in the range of 11 or more and 18 or less, and even more preferably in the range of 12 or more and 17 or less. When the number of theoretical plates An from the bottom of purification column A to the side cut outlet is equal to or more than the above-mentioned lower limit, the XA concentration in the finally obtained diphenyl carbonate tends to be lower, and when it is equal to or more than the above-mentioned lower limit, the amount of loss of diaryl carbonate due to distillation tends to be reduced.

[0022] The diaryl carbonate purification column B has a length L B (cm), inner diameter D B The column has a cylindrical body of 1.2 cm and an internal structure. The column has an inlet B1 in the middle and a side cut outlet B2 between the inlet B1 and the column bottom. The number of stages of the internals from the inlet B1 to the top is n. B1 , the number of internal stages between the inlet B1 and the side cut outlet B2 is n B2 , the number of internal stages below the side cut outlet B2 is n B3 The total number of stages (n B1 +n B2 +n B3 ) is n B A continuous multi-stage distillation column having a L B , D B , n B1 , n B2 , n B3 , n B are preferably continuous multi-stage distillation columns satisfying the following formulas (25) to (30), respectively. 1000 ≦ L B ≦ 5000 formula (25) 100 ≦ D B ≦ 1000 formula (26) 5 ≦ n B1 ≦ 20 Equation (27) 12 ≦ n B2 ≦ 40 Equation (28) 3 ≦ n B3 ≦ 15 Equation (29) 20 ≦ n B ≦ 70 Formula (30)

[0023] By simultaneously satisfying all of these conditions, high purity diaryl carbonate tends to be stably produced from a mixture containing diaryl carbonate on an industrial scale of 0.5 tons or more per hour, for example, for a long period of time of 2000 hours or more, preferably 3000 hours or more, and more preferably 5000 hours or more. The reason why the method of this embodiment enables the production of high purity diaryl carbonate on an industrial scale with such excellent effects is not clear, but it is presumed to be an effect brought about when the purification column A satisfying the conditions of formulas (19) to (30) and the diaryl carbonate purification column B are combined. The preferred ranges of each factor are shown below.

[0024] L A If L (cm) is 800 or more, the separation efficiency tends to improve because there is a margin for the height of the internals that can be installed inside the purification column A. In addition, in order to reduce the equipment cost while achieving the desired separation efficiency, L A It is preferable to set L to 3000 or less. A (cm) range is 1000≦L A ≦2500, and more preferably 1200≦L A <=2000.

[0025] D A If the diameter of the tube is 100 or more, the desired production volume can be achieved. In order to reduce the equipment cost while achieving the desired production volume, D A It is preferable to set D to 1000 or less. A (cm) range is 200≦D A ≦600, and more preferably 250≦D A ≦450.

[0026] n A If n is 20 or more, the separation efficiency is improved, and the desired high purity can be achieved. In order to achieve the desired separation efficiency while reducing the equipment cost, A It is preferable to set n to 100 or less. AIf n is 100 or less, the pressure difference between the top and bottom of the column can be prevented from becoming too large, which not only facilitates long-term stable operation of the purification column A but also makes it possible to lower the temperature at the bottom of the column, which tends to suppress side reactions. A The range is 30≦n A ≦70, and more preferably 35≦n A ≦60.

[0027] L B When L (cm) is 1000 or more, the separation efficiency tends to improve because there is a margin in the height of the internals that can be installed inside the diaryl carbonate purification column B. In addition, in order to reduce the equipment cost while achieving the desired separation efficiency, B It is preferable to set L to 5000 or less. B (cm) range is 1500≦L B ≦3000, and more preferably 1700≦L B <=2500.

[0028] D B If the diameter of the tube is 100 or more, the desired production volume can be achieved. In order to reduce the equipment cost while achieving the desired production volume, D B It is preferable to set D to 1000 or less. B (cm) range is 150≦D B ≦500, and more preferably 200≦D B <=400.

[0029] n B If n is 20 or more, the separation efficiency of the entire column is improved, and the desired high purity can be achieved. In addition, in order to reduce the equipment cost while achieving the desired separation efficiency, B It is preferable to set n to 70 or less. B When n is 70 or less, the pressure difference between the top and bottom of the column can be prevented from increasing, which not only facilitates long-term stable operation of the diaryl carbonate purification column B but also makes it possible to lower the temperature at the bottom of the column, which tends to suppress side reactions. B The range is 25≦n B≦55, and more preferably 30≦n B Furthermore, in order to stably obtain the desired high purity diaryl carbonate for a long period of time, n B1 , n B2 , n B3 are 5≦n B1 ≦20, 12≦n B2 ≦40, 3≦n B3 It is preferable that the range of n is 7≦n≦15. A more preferable range is 7≦n B1 ≦15, 12≦n B2 ≦30, 3≦n B3 <= 10.

[0030] In the industrial production method of high purity diaryl carbonate of this embodiment, the column cross-sectional area (SA (m 2 The ratio (SA / BsF) of the amount of the column bottom fraction (CO2) extracted from the column (CO2) to the amount of the column bottom fraction (Bs) extracted from the column (CO2) (tons / hour) is preferably in the range of 0.5 to 5, more preferably in the range of 0.7 to 4.5, and even more preferably in the range of 1 to 4. When SA / BsF is equal to or more than the lower limit, an increase in the column bottom temperature due to pressure loss can be suppressed, and losses tend to be reduced, whereas when SA / BsF is equal to or less than the upper limit, the production of by-products due to an increase in residence time can be suppressed, and losses tend to be reduced.

[0031] In the industrial production method of high purity diaryl carbonate of this embodiment, the purification column A preferably contains at least one reboiler selected from the group consisting of forced circulation type, cross pipe falling film type, and thin film evaporation type, more preferably contains at least one reboiler selected from the group consisting of forced circulation type and cross pipe falling film type, and particularly preferably contains a forced circulation type reboiler. When the purification column A contains such a reboiler, the reboiler tube wall temperature can be reduced, and the generation of high boiling points due to local overheating tends to be prevented.

[0032] In addition, when carrying out this embodiment, the purification column A has a column bottom temperature (T A )185~280℃, top pressure (P AThe diaryl carbonate purification column B is operated at a column bottom temperature (T B )185~280℃, top pressure (P B ) It is preferable to operate at 1000 to 20000 Pa.

[0033] T A If the temperature is 185°C or higher, there is no need to lower the pressure at the top of the column, so there is no need to use equipment that maintains a high vacuum, and the equipment can be made smaller. A If the temperature is 280° C. or lower, the generation of high-boiling by-products during distillation tends to be suppressed. A The temperature is preferably in the range of 190 to 240°C, and more preferably in the range of 195 to 230°C.

[0034] P A If the pressure is 1000 Pa or more, there is no need for a large facility to maintain a high vacuum, and P A If the pressure is 20,000 Pa or less, the distillation temperature is lowered and the generation of by-products tends to be suppressed. A is preferably in the range of 2000 to 15000 Pa, and more preferably in the range of 3000 to 13000 Pa.

[0035] T B If the temperature is 185°C or higher, there is no need to lower the pressure at the top of the column, so there is no need to use equipment that maintains a high vacuum, and the equipment can be made smaller. B If the temperature is 280° C. or lower, the generation of high-boiling by-products during distillation tends to be suppressed. B The temperature is preferably in the range of 190 to 240°C, and more preferably in the range of 195 to 230°C.

[0036] P B If the pressure is 1000 Pa or more, there is no need for a large facility to maintain a high vacuum, and P B If the pressure is 20,000 Pa or less, the distillation temperature is lowered and the generation of by-products tends to be suppressed. B is preferably in the range of 2000 to 15000 Pa, and more preferably in the range of 3000 to 13000 Pa.

[0037] In addition, in purification column A and diaryl carbonate purification column B, D A and D. B As long as the inner diameter is within the above range, the inner diameter may be the same from the top to the bottom of the column, or the inner diameter may be partially different. For example, in these continuous multi-stage distillation columns, the inner diameter of the top of the column may be smaller or larger than the inner diameter of the bottom of the column.

[0038] In the industrial production method of high purity diaryl carbonate of this embodiment, the upper column diameter (D B1 (m)) and lower tower diameter (D B2 (m)) (D B1 / D B2 ) is preferably in the range of 0.1 or more and 0.9 or less, more preferably in the range of 0.2 or more and 0.9 or less, and even more preferably in the range of 0.3 or more and 0.8 or less. B1 / D B2 When the temperature is equal to or higher than the lower limit, the increase in the temperature at the bottom of the column due to an increase in pressure drop can be suppressed, and the loss tends to be reduced. When the temperature is equal to or lower than the upper limit, the generation of by-products due to an increase in residence time can be suppressed, and the loss tends to be reduced.

[0039] The purification column A and the diaryl carbonate purification column B used in the separation and purification step are preferably distillation columns having trays and / or packings as internals. In this embodiment, the internal means a portion in the distillation column where gas and liquid are actually contacted. As such trays, for example, bubble trays, perforated plate trays, valve trays, countercurrent trays, Superfrac trays, Maxfrac trays, etc. are preferable, and as packings, random packings such as Raschig rings, Lessing rings, Paul rings, Berl saddles, Intalox saddles, Dixon packing, McMahon packing, and Helipacks, and ordered packings such as Melapack, Gempack, Technopack, Flexipack, Sulzer packing, Goodroll packing, and Glitch grids are preferable. In addition, the "number of internal stages" means the number of trays in the case of trays, and the number of theoretical stages in the case of packings. Therefore, in the case of a multi-stage distillation column having both a tray portion and a portion packed with packings, the number of stages is the sum of the number of trays and the number of theoretical stages.

[0040] The purification column A in the separation and purification step preferably has packing as an internal, and more preferably structured packing as the packing, while the diaryl carbonate purification column B preferably has packing as an internal, and more preferably has one or more structured packing units.

[0041] In the industrial production method of high purity diaryl carbonate of this embodiment, the packing of purification column A and / or purification column B is structured packing, and the structured packing preferably contains at least one selected from the group consisting of Melapak, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, Glitch grid, and gauze packing, more preferably contains at least one selected from the group consisting of Melapak, Flexipak, Sulzer packing, and gauze packing, and is particularly preferably Melapak. When purification column A contains such structured packing, pressure loss is reduced and the operable production range tends to increase.

[0042] The mixture introduced into the purification column A may contain other components in addition to the diaryl carbonate. For example, when the mixture is a reaction mixture obtained by at least one reaction selected from the group consisting of (i) transesterification reaction of dialkyl carbonate with aryl alcohol, (ii) disproportionation reaction of alkylaryl carbonate, and (iii) transesterification reaction of alkylaryl carbonate with aryl alcohol in the presence of a catalyst, the reaction mixture usually contains, in addition to the diaryl carbonate, a catalyst, a dialkyl carbonate, an aromatic monohydroxy compound, an alkylaryl carbonate, by-products, etc. The by-products include by-products with a relatively low boiling point such as alkylaryl ether, and high-boiling by-products such as Fries rearrangement products of alkylaryl carbonate or diaryl carbonate or their derivatives, modified products of diaryl carbonate, and high-boiling substances of unknown structure. For example, when diphenyl carbonate is produced using dimethyl carbonate and phenol as raw materials, reaction by-products include anisole, methyl salicylate, phenyl salicylate, xanthone, phenyl methoxybenzoate, 1-phenoxycarbonyl-2-phenoxycarboxy-phenylene, etc., and usually contain a small amount of high-boiling by-products of unknown structure that are thought to be further reacted with these. Specifically, it contains 0.05 to 2 mass% dialkyl carbonate, 1 to 20 mass% phenol, 0.05 to 2 mass% alkyl phenyl ether, 10 to 45 mass% alkyl phenyl carbonate, 50 to 80 mass% diphenyl carbonate, 0.1 to 5 mass% high-boiling by-products, and 0.001 to 5 mass% catalyst, so it is preferable to continuously supply this continuously extracted column bottom liquid as it is to the purification column A in the separation and purification step.

[0043] The composition of the reaction mixture varies depending on the conditions of the transesterification reaction between the dialkyl carbonate and the aryl alcohol, the type and amount of the catalyst, etc., but as long as the transesterification reaction is carried out under certain conditions, a reaction mixture of almost constant composition can be produced, so the composition of the reaction mixture supplied to the purification column A is almost constant. However, in the separation and purification step, as long as the composition of the reaction mixture is within the above range, it can be separated with almost the same separation efficiency even if it varies. This is one of the features of the separation and purification step used in this embodiment.

[0044] In the separation and purification step, for example, in order to continuously supply the bottom liquid of the second continuous multi-stage distillation column for the transesterification reaction of dialkyl carbonate with aryl alcohol into purification column A, it may be supplied in liquid form from one or several inlets installed below the middle part of the purification column A, or it is also a preferred method to supply it into the column via the reboiler from a pipe installed at the bottom of the reboiler of the purification column A. The amount of the bottom liquid of the second continuous multi-stage distillation column supplied to purification column A varies depending on the production amount of high purity diaryl carbonate to be produced, the concentration of diaryl carbonate in the reaction mixture, the separation conditions of the purification column A, etc., but is usually about 2 tons / hr or more, preferably about 6 tons / hr or more, and more preferably about 10 tons / hr or more.

[0045] The mixture continuously fed to the purification column A is separated into a top component (At) consisting of a majority of compounds with a boiling point lower than that of diaryl carbonate, such as unreacted raw materials, alkylaryl ethers, and alkylaryl carbonates, a side cut component (As) containing diaryl carbonate, and a bottom component (Ab) containing a small amount of diaryl carbonate, catalyst, and high boiling by-products. A small amount of alkylaryl carbonate may be contained in the bottom component (Ab). These organic matters in the bottom component help to dissolve the catalyst components and keep them in a liquid state. The whole or part of this bottom component (Ab) is normally fed as it is into the first continuous multi-stage distillation column and / or the second continuous multi-stage distillation column for the transesterification reaction of dialkyl carbonate and aryl alcohol as a catalyst component for transesterification reaction, and recycled and reused, but in some cases, it is separated from the organic matter in a catalyst recovery step and then regenerated as a catalyst and recycled and reused.

[0046] In the separation and purification step, by-products and catalyst components having a boiling point higher than that of diphenyl carbonate, such as phenyl salicylate, xanthone, phenyl methoxybenzoate, and 1-phenoxycarbonyl-2-phenoxycarboxy-phenylene, are almost completely separated as a bottom component (Ab) in this purification column A. One of the features of the separation and purification step is that these high boiling by-products can be extracted with almost no inclusion in the side cut component (As). In the separation and purification step, 80% or more, preferably 84% or more, and more preferably 87% or more of the diaryl carbonate in the mixture continuously supplied to purification column A can be extracted from the side cut. In the separation and purification step, although it depends on the composition of the mixture supplied to the purification column A, usually 10 to 40 mass% of the continuously supplied liquid is continuously withdrawn from the top of the column as the column top component (At), 40 to 70 mass% is continuously withdrawn from the side cut as the side cut component (As), and 10 to 40 mass% is continuously withdrawn from the bottom of the column as the column bottom component (Ab). The composition of the side cut component (As) is usually 0 to 10 mass% dialkyl carbonate, 0 to 10 mass% aryl alcohol, 0 to 10 mass% alkyl aryl ether, 1 to 20 mass% alkyl aryl carbonate, and 50 to 99 mass% diaryl carbonate, and the content of high-boiling by-products is usually 8000 ppm or less, preferably 5000 ppm or less, and more preferably 3000 ppm.

[0047] In the separation and purification step, the reflux ratio of the purification column A is preferably in the range of 1 to 15, more preferably 2 to 12, and further preferably 2.5 to 6.5.

[0048] The amount of the side cut component (As) continuously extracted from the top of the purification column A is usually 10 to 40 mass% of the mixture supplied to the purification column A as described above, and this is continuously supplied as it is to the diaryl carbonate purification column B from an inlet B1 provided in the middle of the purification column B, and is continuously separated into three components, a top component (Bt), a side cut component (Bs), and a bottom component (Bb). All components having a boiling point lower than that of the diaryl carbonate contained in the side cut component (As) of the purification column A supplied to the purification column B are continuously extracted from the top of the column as the top component (Bt), and a small amount of liquid is continuously extracted from the bottom of the column. The top component (Bt) contains a small amount of diaryl carbonate, and the amount is usually 0.01 to 1.0 mass%, preferably 0.1 to 0.8 mass%, based on the diaryl carbonate supplied. The diaryl carbonate in this overhead component (Bt) is separated and recovered in another distillation column that separates the overhead component (Bt), but it is also a preferred method to separate it as a bottom component in this other distillation column and recover it by returning it to the purification column A and / or the diaryl carbonate purification column B.

[0049] The column bottom component (Bb) is composed of diaryl carbonate and a small amount of high boiling point by-products concentrated to about several percent. One of the features of this embodiment is that the amount of diaryl carbonate in the column bottom component (Bb) extracted from the column bottom is very small, and the amount is usually 1 to 15 mass% based on the diaryl carbonate supplied.

[0050] High purity diaryl carbonate is continuously withdrawn from the side cut withdrawal port B2 at a flow rate of usually 0.5 tons or more, preferably 1 ton / hr or more, more preferably 3 tons / hr or more, and even more preferably 5 tons / hr or more. This amount usually corresponds to about 70 to 90 mass% of the diaryl carbonate supplied to the purification column B.

[0051] The purity of the diaryl carbonate obtained as the side cut component (Bs) in the separation and purification step is usually 99% or more, preferably 99.9% or more, more preferably 99.99% or more, and even more preferably 99.999% or more. In this embodiment, high purity means 99% or more, preferably 99.9% or more, more preferably 99.99% or more, and even more preferably 99.999% or more. The content of high-boiling impurities in the high-purity diphenyl carbonate obtained by carrying out the transesterification reaction step of dialkyl carbonate and aryl alcohol and the separation and purification step using dimethyl carbonate and phenol as raw materials is preferably 30 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less for phenyl salicylate, preferably 30 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less for xanthone, preferably 30 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less for phenyl methoxybenzoate, preferably 30 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less for 1-phenoxycarbonyl-2-phenoxycarboxy-phenylene. The total content of these high-boiling by-products is preferably 100 ppm or less, more preferably 50 ppm or less, and even more preferably 10 ppm or less. In addition, the content of diaryl carbonate in the side cut component (As) is preferably 80% by mass or more, and the content of diaryl carbonate in the side cut component (Bs) is preferably 99.1% by mass or more. Here, the upper limit of the content of diaryl carbonate in the side cut component (Bs) is not particularly limited, but is, for example, 99.8% by mass. In the side cut component (As), the content of the diaryl carbonate is preferably 80% by mass or more, more preferably 85% by mass or more. The upper limit of the content of the diaryl carbonate in the side cut component (As) is not particularly limited, but may be, for example, 99.5% or less, or 99.2% or less. In this embodiment, the purity and impurity content of the diaryl carbonate (for example, diphenyl carbonate) can be measured by the method described in the Examples below.

[0052] In addition, in this embodiment, when halogen-free raw materials and catalysts are used, the halogen content of the obtained diaryl carbonate is preferably 0.1 ppm or less, more preferably 10 ppb or less, and even more preferably 1 ppb or less (outside the detection limit of ion chromatography).

[0053] In the separation and purification step, the reflux ratio of the diaryl carbonate purification column B is in the range of 0.01-10, preferably 0.1-8, and more preferably 0.5-5.

[0054] The materials constituting the purification column A, diaryl carbonate purification column B, and liquid-contacting parts used in this embodiment are mainly metal materials such as carbon steel and stainless steel, but stainless steel is preferred from the viewpoint of the quality of the diaryl carbonate produced.

[0055] By carrying out the method of this embodiment, for example, high purity diaryl carbonate necessary for producing a high quality and high performance aromatic polycarbonate from a cyclic carbonate and an aryl alcohol (e.g., phenol) can be produced on an industrial scale of 0.5 tons or more, preferably 1 ton or more, more preferably 2 tons or more, and even more preferably 3 tons or more per hour. In this embodiment, the industrial scale means 0.5 tons or more per hour, preferably 1 ton or more, more preferably 2 tons or more, and even more preferably 3 tons or more.

[0056] The method for producing the diaryl carbonate-containing mixture will be described in detail below. (i) The method for producing a reaction mixture containing an alkylaryl carbonate by a transesterification reaction between a dialkyl carbonate and an aryl alcohol (hereinafter also referred to as an "aromatic monohydroxy compound") is not particularly limited. For example, there may be mentioned a method in which a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound is carried out in the presence of a homogeneous catalyst, and a reaction mixture containing an alcohol is continuously withdrawn from the top of a column, and a reaction mixture containing an alkylaryl carbonate is continuously withdrawn from the bottom of the column.

[0057] The thus obtained reaction mixture containing the alkylaryl carbonate is continuously fed into a reactive distillation column consisting of a continuous multi-stage distillation column in which a homogeneous catalyst is present, and the transesterification reaction and distillation are carried out simultaneously in the column, and the resulting low-boiling reaction mixture containing the dialkyl carbonate is continuously withdrawn in gaseous form from the top of the column, and the high-boiling reaction mixture containing the diaryl carbonate is continuously withdrawn in liquid form from the bottom of the column. This transesterification reaction includes a reaction in which the alkoxy group of the alkylaryl carbonate is exchanged with the aryloxy group of the aromatic monohydroxy compound present in the system to eliminate alcohols, and a reaction in which the alkylaryl carbonate is converted into a diaryl carbonate and a dialkyl carbonate by a disproportionation reaction, which is a transesterification reaction between two molecules of alkylaryl carbonate. In the reactive distillation column, the disproportionation reaction of the alkylaryl carbonate mainly occurs.

[0058] The reaction mixture containing the alkylaryl carbonate used as the raw material here may be of high purity, but may also contain other compounds, for example, may contain the dialkyl carbonate and / or aromatic monohydroxy compound used to obtain the alkylaryl carbonate, or may contain compounds and reaction by-products generated in this step and / or other steps, such as alcohols, alkylaryl ethers, and diaryl carbonate. It is also a preferred method to use the transesterification reaction mixture of the dialkyl carbonate and aromatic monohydroxy compound as the raw material without separating unreacted substances and catalysts. When industrially carried out as in this embodiment, it is preferable to use the dialkyl carbonate and aromatic monohydroxy compound used to obtain the alkylaryl carbonate as the raw material, which are not only the dialkyl carbonate and aromatic monohydroxy compound newly introduced into the reaction system, but also those recovered from this step and / or other steps.

[0059] The continuous multi-stage distillation column used as the reactive distillation column is preferably a distillation column having trays and / or packings as internals. In this embodiment, the internals refer to the portion of the distillation column where gas and liquid are actually contacted. Examples of such trays include bubble trays, perforated plate trays, valve trays, countercurrent trays, Super Frac trays, and Max Frac trays. Examples of packing include irregular packing such as Raschig rings, Lessing rings, Paul rings, Berl saddles, Intalox saddles, Dixon packing, McMahon packing, and Helipack, and ordered packing such as Melapack, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, and Glitch grid.

[0060] Here, the reaction between the alkylaryl carbonate and the aromatic monohydroxy compound present in the system has an extremely small equilibrium constant and a slow reaction rate, and the disproportionation reaction of the alkylaryl carbonate, which is the main reaction, is also an equilibrium reaction with a small equilibrium constant and a slow reaction rate. As a continuous multi-stage distillation column for reactive distillation in which such a reaction is carried out, it is preferable that the internal is a multi-stage distillation column having both packing and trays. In addition, in this distillation column, it is preferable that the part packed with the packing is installed at the top and the tray part is installed at the bottom. In addition, it is preferable that the packing is structured packing, and more preferably, one or more of the structured packing is used. And, it is preferable that the structured packing is at least one selected from Melapack, Gempack, Technopack, Flexipak, Sulzer Packing, Goodroll Packing, and Glitch Grid.

[0061] Furthermore, as a reactive distillation column, it is preferable that the internal tray is a sieve tray having a sieve portion and a downcomer portion, which is particularly excellent in terms of the relationship between function and equipment cost. 2 It is preferable that the number of holes is 100 to 1000 per square meter. More preferable number of holes is 100 to 1000 per square meter. 2 The number of holes in the sieve tray is preferably 120 to 900, and more preferably 150 to 800. The cross-sectional area of ​​each hole in the sieve tray is preferably 0.5 to 5 cm. 2 More preferably, the cross-sectional area per hole is 0.7 to 4 cm. 2 and more preferably 0.9 to 3 cm 2 Furthermore, the sieve tray has a sieve area of ​​1 m 2 It has 100 to 1000 holes per hole, and the cross-sectional area of ​​each hole is 0.5 to 5 cm 2 Furthermore, it is particularly preferable that the structured packing is at least one selected from the group consisting of Melapak, Gempack, Technopack, Flexipak, Sulzer packing, Goodroll packing, and Glitchgrid, and the perforated tray has a perforated tray area of ​​1 m 2The perforated tray has 100 to 1000 holes per square meter, and the cross-sectional area of ​​each hole in the perforated tray is 0.5 to 5 cm. 2 This is particularly preferred in the case of a continuous multi-stage distillation column.

[0062] In this embodiment, when the reactive distillation step is carried out, it is preferable to continuously produce diaryl carbonate by continuously supplying a raw material containing alkylaryl carbonate into a continuous multi-stage distillation column in which a homogeneous catalyst is present, simultaneously carrying out reaction and distillation in the column, continuously withdrawing the resulting low-boiling reaction mixture containing dialkyl carbonate and alcohols in a gaseous state from the top of the column, and continuously withdrawing the high-boiling reaction mixture having diaryl carbonate as the main reaction product in a liquid state from the bottom of the column. In this embodiment, any method may be used to cause the catalyst to be present in the reactive distillation column, but since it is a homogeneous catalyst that dissolves in the raw material or reaction liquid, it is preferable to supply it into the distillation column from a position above the middle part of the distillation column. In this case, the catalyst solution dissolved in the raw material or reaction liquid may be introduced together with the raw material, or this catalyst solution may be introduced from an inlet separate from the raw material. In addition, it is also preferable to use the catalyst contained in the raw material used to produce the raw material containing alkylaryl carbonate as the catalyst for this reactive distillation step as it is, but the above-mentioned catalyst can also be newly added as necessary. The amount of the catalyst used here varies depending on reaction conditions such as the type of catalyst used, the types of raw materials and their quantitative ratios, the reaction temperature, and the reaction pressure, but is usually 0.0001 to 30 mass%, preferably 0.005 to 10 mass%, and more preferably 0.001 to 1 mass%, expressed as a ratio to the total mass of the raw materials.

[0063] The low-boiling reaction mixture continuously extracted from the top of the reactive distillation column may contain aromatic monohydroxy compounds, alkylaryl ethers, and unreacted alkylaryl carbonates present in the system. It is preferable to recycle and reuse this low-boiling reaction mixture in the transesterification reactor of dialkyl carbonate and aromatic monohydroxy compound. It is also a preferred method to condense the gas components extracted from the top of the reactive distillation column and then return a part of them to the top of the distillation column by refluxing. In this case, the reflux ratio is in the range of 0.05 to 10, preferably 0.08 to 5, and more preferably 0.1 to 2.

[0064] In order to continuously supply the raw material containing the alkylaryl carbonate into the reactive distillation column, it is preferable to supply it in liquid and / or gaseous form from one or several inlets installed in the upper or middle part of the column, but below the gas outlet at the top of the distillation column. In addition, when using a distillation column having a packing section at the top and a tray section at the bottom, it is preferable to install at least one inlet between the packing section and the tray section. In addition, when the packing is composed of two or more structured packings, it is also a preferable method to install an inlet at the interval constituting these structured packings.

[0065] The reaction time of the transesterification reaction is considered to correspond to the average residence time of the reaction liquid in the reactive distillation column, which varies depending on the shape and number of stages of the internals of the distillation column, the amount of raw material supplied, the type and amount of catalyst, the reaction conditions, etc., but is usually 0.01 to 10 hours, preferably 0.05 to 5 hours, and more preferably 0.1 to 3 hours.

[0066] The reaction temperature of the transesterification reaction varies depending on the type of raw material compound and the type and amount of catalyst used, but is usually 100 to 350°C. In order to increase the reaction rate, it is preferable to increase the reaction temperature, but a high reaction temperature is undesirable because it makes side reactions more likely to occur, and increases the by-products such as Fries rearrangement products of alkyl aryl ethers and diaryl carbonates and their ester compounds. In this sense, the preferred reaction temperature is in the range of 130 to 280°C, more preferably 150 to 260°C, and even more preferably 180 to 240°C. The reaction pressure varies depending on the type and composition of the raw material compound used, the reaction temperature, etc., but may be reduced pressure, normal pressure, or increased pressure, and the column top pressure is usually 0.1 to 2×10 7 Pa, preferably 10 3 ~10 6 Pa, more preferably 5×10 3 ~10 5 This is carried out within the range.

[0067] In addition to diaryl carbonate, the high-boiling reaction mixture containing diaryl carbonate continuously extracted from the bottom of the reactive distillation column usually contains a catalyst, a dialkyl carbonate, an aromatic monohydroxy compound, an alkylaryl carbonate, by-products, etc. The by-products include by-products with relatively low boiling points such as alkylaryl ethers, and high-boiling by-products such as Fries rearrangement products of alkylaryl carbonates and diaryl carbonates and their derivatives, modified products of diaryl carbonates, and high-boiling substances of unknown structure. For example, when diphenyl carbonate is produced using dimethyl carbonate and phenol as raw materials, reaction by-products include anisole, methyl salicylate, phenyl salicylate, xanthone, phenyl methoxybenzoate, 1-phenoxycarbonyl-2-phenoxycarboxy-phenylene, etc., and usually contains a small amount of high-boiling by-products of unknown structure that are thought to have been further reacted with these.

[0068] (i) The dialkyl carbonate used in the transesterification reaction between a dialkyl carbonate and an aryl alcohol is represented by the general formula (I). R1 OCOOR 1 (I) Here, R 1 represents an alkyl group having 1 to 10 carbon atoms, an alicyclic group having 3 to 10 carbon atoms, or an aralkyl group having 6 to 10 carbon atoms. 1 Examples of the alkyl group include alkyl groups such as methyl, ethyl, propyl (each isomer), allyl, butyl (each isomer), butenyl (each isomer), pentyl (each isomer), hexyl (each isomer), heptyl (each isomer), octyl (each isomer), nonyl (each isomer), decyl (each isomer), and cyclohexylmethyl; alicyclic groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl; and aralkyl groups such as benzyl, phenethyl (each isomer), phenylpropyl (each isomer), phenylbutyl (each isomer), and methylbenzyl (each isomer). These alkyl groups, alicyclic groups, and aralkyl groups may be substituted with other substituents such as lower alkyl groups, lower alkoxy groups, cyano groups, and halogens, or may have unsaturated bonds.

[0069] Such an R 1Examples of dialkyl carbonates having the formula (I) include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (each isomer), diallyl carbonate, dibutenyl carbonate (each isomer), dibutyl carbonate (each isomer), dipentyl carbonate (each isomer), dihexyl carbonate (each isomer), diheptyl carbonate (each isomer), dioctyl carbonate (each isomer), dinonyl carbonate (each isomer), didecyl carbonate (each isomer), dicyclopentyl carbonate, dicyclohexyl carbonate, Silcarbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (each isomer), di(phenylpropyl) carbonate (each isomer), di(phenylbutyl) carbonate (each isomer), di(chlorobenzyl) carbonate (each isomer), di(methoxybenzyl) carbonate (each isomer), di(methoxymethyl) carbonate, di(methoxyethyl) carbonate (each isomer), di(chloroethyl) carbonate (each isomer), di(cyanoethyl) carbonate (each isomer), etc.

[0070] Among these, the one preferably used is R 1 is a dialkyl carbonate having an alkyl group having 4 or less carbon atoms and containing no halogen, and dimethyl carbonate is particularly preferred. Among the preferred dialkyl carbonates, more preferred are dialkyl carbonates produced in a state substantially free of halogen, such as those produced from an alkylene carbonate substantially free of halogen and an alcohol substantially free of halogen.

[0071] The aryl alcohol (aromatic monohydroxy compound) is represented by the following general formula (II), and may be any compound in which a hydroxyl group is directly bonded to an aromatic group. Ar 1 OH (II) Here, Ar 1 represents an aromatic group having 5 to 30 carbon atoms. 1Examples of aromatic monohydroxy compounds having the formula (I) include phenol; cresol (each isomer), xylenol (each isomer), trimethylphenol (each isomer), tetramethylphenol (each isomer), ethylphenol (each isomer), propylphenol (each isomer), butylphenol (each isomer), diethylphenol (each isomer), methylethylphenol (each isomer), methylpropylphenol (each isomer), dipropylphenol (each isomer), methylbutylphenol (each isomer), pentylphenol, Examples of the aromatic monohydroxy compounds that can be used include various alkylphenols such as phenylphenol (each isomer), hexylphenol (each isomer), and cyclohexylphenol (each isomer); various alkoxyphenols such as methoxyphenol (each isomer), and ethoxyphenol (each isomer); arylalkylphenols such as phenylpropylphenol (each isomer); naphthol (each isomer) and various substituted naphthols; and heteroaromatic monohydroxy compounds such as hydroxypyridine (each isomer), hydroxycoumarin (each isomer), and hydroxyquinoline (each isomer). Among these aromatic monohydroxy compounds, the one that can be used preferably is Ar 1 The aromatic monohydroxy compounds are unsubstituted or substituted phenols each having an aromatic group having 6 to 10 carbon atoms, and unsubstituted phenols are particularly preferred. Among these aromatic monohydroxy compounds, those which are substantially free of halogens are preferably used.

[0072] The molar ratio of the dialkyl carbonate and aromatic monohydroxy compound used to obtain the reaction mixture containing the alkylaryl carbonate as the raw material must be 0.5-3. Outside this range, the amount of unreacted material remaining is large compared to the required amount of the target alkylaryl carbonate, which is not efficient and requires a lot of energy to recover them. In this sense, the molar ratio is more preferably 0.5-5, and even more preferably 1-3.

[0073] The catalyst used here is not particularly limited, but examples thereof include homogeneous catalysts that contain metals such as Pb, Cu, Zn, Fe, Co, Ni, Al, Ti, V, and Sn and dissolve in the reaction system. Therefore, catalyst species in which these metal components are bonded to organic groups are preferably used. Of course, these catalyst components may be reacted with organic compounds present in the reaction system, such as aliphatic alcohols, aromatic monohydroxy compounds, alkylaryl carbonates, diaryl carbonates, and dialkyl carbonates, or may be heat-treated with raw materials or products prior to the reaction. The catalyst used here is preferably one that is highly soluble in the reaction liquid under the reaction conditions. In this sense, preferred catalysts include, but are not limited to, PbO, Pb(OH)2, Pb(OPh)2; TiCl4, Ti(OMe)4, (MeO)Ti(OPh)3, (MeO)2Ti(OPh)2, (MeO)3Ti(OPh), Ti(OPh)4; SnCl4, Sn(OPh)4, Bu2SnO, Bu2Sn(OPh)2; FeCl3, Fe(OH)3, Fe(OPh)3, etc., or those which have been treated with phenol or a reaction solution, etc.

[0074] In this embodiment, it is particularly preferable to use raw materials and catalysts that do not contain halogen, and in this case, the diaryl carbonate produced does not contain any halogen, and is therefore important as a raw material when industrially producing polycarbonate by the transesterification method. This is because the presence of halogen in the polymerization raw materials, even in an amount less than 1 ppm, can inhibit the polymerization reaction, reduce the physical properties of the produced polycarbonate, or cause coloration.

[0075] In the industrial production method of high purity diaryl carbonate of this embodiment, other methods for obtaining the mixture to be introduced into purification column A are not particularly limited, but include, for example, a method using two continuous multi-stage distillation columns as follows. That is, the industrial production method of high purity diaryl carbonate of the present embodiment includes the steps of: a step of continuously supplying a dialkyl carbonate and an aryl alcohol into a first continuous multi-stage distillation column in the presence of a catalyst, simultaneously carrying out reaction and distillation in the first continuous multi-stage distillation column, continuously withdrawing a first column low-boiling point reaction mixture containing the produced alcohol in a gaseous state from an upper portion of the first continuous multi-stage distillation column, and continuously withdrawing a first column high-boiling point reaction mixture containing the produced alkyl aryl carbonate in a liquid state from a lower portion of the first continuous multi-stage distillation column, thereby continuously producing an alkyl aryl carbonate; It is preferable that the method further comprises a step of continuously supplying the first column high boiling point reaction mixture into a second continuous multi-stage distillation column in the presence of a catalyst, simultaneously carrying out reaction and distillation in the second continuous multi-stage distillation column, continuously withdrawing the second column low boiling point reaction mixture containing the produced dialkyl carbonates in a gaseous state from the top of the second continuous multi-stage distillation column, and continuously withdrawing the second column high boiling point reaction mixture containing the produced diaryl carbonate in a liquid state from the bottom of the second continuous multi-stage distillation column to continuously produce diaryl carbonate (these two steps are hereinafter collectively referred to as "step (II)"). It is preferable that the second column high boiling point reaction mixture obtained in step (II) is the mixture to be introduced into purification column A.

[0076] In the industrial production method of high purity diaryl carbonate of this embodiment, the diaryl carbonate is preferably diphenyl carbonate.

[0077] The method for obtaining the dialkyl carbonate used as the raw material in step (II) is not particularly limited, but may be, for example, a method in which step (I) is carried out to continuously produce dialkyl carbonate and diols from cyclic carbonate and aliphatic monohydric alcohols on an industrial scale. The reaction in step (I) is a reversible transesterification reaction represented by the following formula.

[0078] [ka]

[0079] (In formula 1, R 1represents a divalent group -(CH2)m- (m is an integer of 2 to 6), one or more hydrogen atoms of which may be substituted with an alkyl group or an aryl group having 1 to 10 carbon atoms. 2 represents a monovalent aliphatic group having 1 to 12 carbon atoms, one or more hydrogen atoms of which may be substituted with an alkyl group or aryl group having 1 to 10 carbon atoms.

[0080] As such cyclic carbonates, for example, alkylene carbonates such as ethylene carbonate and propylene carbonate, 1,3-dioxacyclohex-2-one, 1,3-dioxacyclohept-2-one, etc. are preferably used, with ethylene carbonate and propylene carbonate being more preferably used from the viewpoint of ease of availability, and ethylene carbonate being particularly preferably used.

[0081] In addition, the aliphatic monohydric alcohols used have a boiling point lower than that of the diols produced.Therefore, it may vary depending on the type of cyclic carbonate used, but for example, methanol, ethanol, propanol (each isomer), allyl alcohol, butanol (each isomer), 3-buten-1-ol, amyl alcohol (each isomer), hexyl alcohol (each isomer), heptyl alcohol (each isomer), octyl alcohol (each isomer), nonyl alcohol (each isomer), decyl alcohol (each isomer), undecyl alcohol (each isomer), dodecyl alcohol (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, phenethyl alcohol (each isomer), phenylpropanol (each isomer), and the like. Furthermore, these aliphatic monohydric alcohols may be substituted with a substituent such as a halogen, a lower alkoxy group, a cyano group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyloxy group, or a nitro group.

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

[0083] When carrying out the reactive distillation in step (I), any method may be used to cause a catalyst to be present in the reactive distillation column. For example, in the case of a homogeneous catalyst that dissolves in the reaction liquid under reaction conditions, the catalyst can be caused to be present in the liquid phase in the reactive distillation column by continuously supplying the catalyst into the reactive distillation column. Alternatively, in the case of a heterogeneous catalyst that does not dissolve in the reaction liquid under reaction conditions, a solid catalyst can be placed in the reactive distillation column to cause the catalyst to be present in the reaction system. Alternatively, a combination of these methods may be used.

[0084] When the homogeneous catalyst is continuously fed into the reactive distillation column, it may be fed simultaneously with the cyclic carbonate and / or the aliphatic monohydric alcohol, or may be fed to a position different from the raw material. Since the reaction actually proceeds in the distillation column in the region below the catalyst feed position, it is preferable to feed the catalyst in the region between the top of the column and a little below the raw material feed position. The number of stages in which the catalyst is present is preferably 5 or more, more preferably 7 or more, and even more preferably 10 or more.

[0085] In addition, when a heterogeneous solid catalyst is used, the number of stages in which the catalyst is present is preferably 5 or more, more preferably 7 or more, and even more preferably 10 or more. A solid catalyst that also has an effect as a packing for a distillation column can also be used.

[0086] The catalyst used in step (I) is not particularly limited, but may be, for example, Alkali metals and alkaline earth metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, and barium; Basic compounds such as hydrides, hydroxides, alkoxides, aryloxides, and amides of alkali metals and alkaline earth metals; Basic compounds such as carbonates, bicarbonates, and organic acid salts of alkali metals and alkaline earth metals; Tertiary amines such as triethylamine, tributylamine, trihexylamine, and benzyldiethylamine; nitrogen-containing heteroaromatic compounds such as N-alkylpyrrole, N-alkylindole, oxazole, N-alkylimidazole, N-alkylpyrazole, oxadiazole, pyridine, alkylpyridine, quinoline, alkylquinoline, isoquinoline, alkylisoquinoline, acridine, alkylacridine, phenanthroline, alkylphenanthroline, pyrimidine, alkylpyrimidine, pyrazine, alkylpyrazine, triazine, and alkyltriazine; Cyclic amidines such as diazabicycloundecene (DBU) and diazabicyclononene (DBN); Thallium compounds such as thallium oxide, thallium halides, thallium hydroxide, thallium carbonate, thallium nitrate, thallium sulfate, and organic acid salts of thallium; Tin compounds such as tributyl methoxytin, tributyl ethoxytin, dibutyl dimethoxytin, diethyl diethoxytin, dibutyl diethoxytin, dibutyl phenoxytin, diphenyl methoxytin, dibutyl tin acetate, tributyl tin chloride, and tin 2-ethylhexanoate; Zinc compounds such as dimethoxyzinc, diethoxyzinc, ethylenedioxyzinc, and dibutoxyzinc; Aluminum compounds such as aluminum trimethoxide, aluminum triisopropoxide, and aluminum tributoxide; Titanium compounds such as tetramethoxytitanium, tetraethoxytitanium, tetrabutoxytitanium, dichlorodimethoxytitanium, tetraisopropoxytitanium, titanium acetate, and titanium acetylacetonate; Phosphorus compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, triphenylphosphine, tributylmethylphosphonium halide, trioctylbutylphosphonium halide, and triphenylmethylphosphonium halide; zirconium compounds such as zirconium halides, zirconium acetylacetonate, zirconium alkoxides, and zirconium acetate; Lead and lead-containing compounds, for example lead oxides such as PbO, PbO2, Pb3O4; Lead sulfides such as PbS, Pb2S3, and PbS2; Lead hydroxides such as Pb(OH)2, Pb3O2(OH)2, Pb2[PbO2(OH)2], and Pb2O(OH)2; Naphthalites such as Na2PbO2, K2PbO2, NaHPbO2, and KHPbO2; Plumbates such as Na2PbO3, Na2H2PbO4, K2PbO3, K2[Pb(OH)6], K4PbO4, Ca2PbO4, and CaPbO3; Lead carbonates and their basic salts, such as PbCO3, 2PbCO3·Pb(OH)2; Alkoxyleads, aryloxyleads such as Pb(OCH3)2, (CH3O)Pb(OPh), Pb(OPh)2; Lead salts of organic acids such as Pb(OCOCH3)2, Pb(OCOCH3)4, Pb(OCOCH3)2·PbO·3H2O, and their carbonates and bases; Organolead compounds such as Bu4Pb, Ph4Pb, Bu3PbCl, Ph3PbBr, Ph3Pb (or Ph6Pb2), Bu3PbOH, and Ph2PbO (Bu stands for butyl and Ph stands for phenyl); Alloys of lead such as Pb-Na, Pb-Ca, Pb-Ba, Pb-Sn, Pb-Sb; Lead minerals such as arsenite and pyrite, and hydrates of these lead compounds; Examples include:

[0087] These compounds can be used as homogeneous catalysts when they are soluble in the reaction raw materials, reaction mixture, reaction by-products, etc., and can be used as solid catalysts when they are not soluble. Furthermore, it is also a preferred method to dissolve these compounds in the reaction raw materials, reaction mixture, reaction by-products, etc. beforehand, or to use a mixture dissolved by reacting the compounds as a homogeneous catalyst.

[0088] Further, ion exchangers such as anion exchange resins having a tertiary amino group, ion exchange resins having an amide group, ion exchange resins having at least one exchange group selected from the group consisting of sulfonic acid group, carboxylic acid group, and phosphoric acid group, and solid strongly basic anion exchangers having a quaternary ammonium group as an exchange group; and solid inorganic compounds such as silica, silica-alumina, silica-magnesia, aluminosilicate, gallium silicate, various zeolites, various metal-exchanged zeolites, and ammonium-exchanged zeolites can be used as catalysts.

[0089] As the solid catalyst, a solid strongly basic anion exchanger having a quaternary ammonium group as an exchange group is particularly preferably used. Such a solid strongly basic anion exchanger is not particularly limited, but examples thereof include a strongly basic anion exchange resin having a quaternary ammonium group as an exchange group, a cellulose strongly basic anion exchanger having a quaternary ammonium group as an exchange group, and an inorganic carrier-supported strongly basic anion exchanger having a quaternary ammonium group as an exchange group. As a strongly basic anion exchange resin having a quaternary ammonium group as an exchange group, it is not particularly limited, but for example, a styrene-based strongly basic anion exchange resin is preferably used. The styrene-based strongly basic anion exchange resin is a strongly basic anion exchange resin having a quaternary ammonium (I type or II type) as an exchange group, with a copolymer of styrene and divinylbenzene as a base, and is, for example, represented by the following formula:

[0090] [ka]

[0091] In the formula, X represents an anion, and typically, X is F - , Cl - , Br - , I - , HCO3 - , CO3 2- , CH3CO2 - , HCO2 - , IO3 - , BrO3 - , ClO3 - At least one anion selected from the group consisting of - , Br - , HCO3 - , CO3 2- At least one anion selected from the following is used. As the structure of the resin matrix, either a gel type or a macroreticular type (MR type) can be used, but the MR type is particularly preferred from the viewpoint of high resistance to organic solvents.

[0092] The strongly basic cellulose anion exchanger having a quaternary ammonium group as an exchange group is not particularly limited, but may be, for example, a cellulose having an exchange group of -OCH2CH2NR3X obtained by trialkylaminoethylating some or all of the -OH groups of cellulose. Here, R represents an alkyl group, and typically methyl, ethyl, propyl, butyl, etc. are used, and methyl and ethyl are preferably used. X represents an anion as described above.

[0093] The inorganic carrier-supported strong basic anion exchanger having quaternary ammonium groups as exchange groups means that the quaternary ammonium groups -O(CH2)nNR3X are introduced by modifying part or all of the surface hydroxyl groups -OH of the inorganic carrier. Here, R and X are as described above. n is usually an integer of 1 to 6, and preferably n=2. The inorganic carrier is not particularly limited, but for example, silica, alumina, silica alumina, titania, zeolite, etc. can be used, preferably silica, alumina, and silica alumina are used, and particularly preferably silica is used. Any method can be used to modify the surface hydroxyl groups of the inorganic carrier.

[0094] A commercially available solid strongly basic anion exchanger having a quaternary ammonium group as an exchange group can also be used. In this case, it can be used as a transesterification catalyst after ion exchange with a desired anion species as a pretreatment.

[0095] In addition, solid catalysts made of macroreticular and gel-type organic polymers to which at least one nitrogen-containing heterocyclic group is bonded, or inorganic supports to which at least one nitrogen-containing heterocyclic group is bonded, are also preferably used as transesterification catalysts. Furthermore, solid catalysts in which some or all of these nitrogen-containing heterocyclic groups have been converted to quaternary salts are also used. In addition, solid catalysts such as ion exchangers can also function as packings.

[0096] The amount of catalyst used in step (I) varies depending on the type of catalyst used, but when a homogeneous catalyst that dissolves in the reaction liquid under reaction conditions is continuously fed, it is usually used in an amount of 0.0001 to 50 mass%, preferably 0.005 to 20 mass%, more preferably 0.01 to 10 mass%, expressed as a ratio to the total mass of the cyclic carbonate and the aliphatic monohydric alcohol that are the feed materials. When a solid catalyst is used by placing it in the distillation column, the amount of catalyst is preferably 0.01 to 75 volume%, preferably 0.05 to 60 volume%, more preferably 0.1 to 60 volume%, based on the empty column volume of the distillation column.

[0097] In step (I), there is no particular limitation on the method of continuously supplying the raw materials, cyclic carbonate and aliphatic monohydric alcohol, to the continuous multi-stage distillation column T0, which is a reactive distillation column. For example, any supply method may be used as long as they can be contacted with the catalyst in at least 5 stages, preferably 7 stages, and more preferably 10 stages of the distillation column. That is, the cyclic carbonate and the aliphatic monohydric alcohol can be continuously supplied from the number of inlets required for the stages of the continuous multi-stage distillation column that satisfy the above conditions. In addition, the cyclic carbonate and the aliphatic monohydric alcohol may be introduced into the same stage of the distillation column, or may be introduced into different stages.

[0098] The raw materials, cyclic carbonate and aliphatic monohydric alcohol, are continuously supplied to the continuous multi-stage distillation column T0 in the form of liquid, gas, or a mixture of liquid and gas. In addition to supplying the raw materials to the distillation column in this manner, it is also a preferred method to additionally supply a gaseous raw material from the lower part of the distillation column intermittently or continuously. Another preferred method is to continuously supply the cyclic carbonate to the distillation column in the form of liquid or a gas-liquid mixture at a stage above the stage where the catalyst is present, and to continuously supply the aliphatic monohydric alcohol to the lower part of the distillation column in the form of gas and / or liquid. In this case, it is of course acceptable if the cyclic carbonate contains an aliphatic monohydric alcohol.

[0099] In step (I), the feed material may contain the product dialkyl carbonate and / or diols. The content of the dialkyl carbonate is usually 0 to 40 mass%, preferably 0 to 30 mass%, and more preferably 0 to 20 mass%, expressed in mass% of the dialkyl carbonate in the aliphatic monohydric alcohol / dialkyl carbonate mixture, and the content of the diols is usually 0 to 10 mass%, preferably 0 to 7 mass%, and more preferably 0 to 5 mass%, expressed in mass% of the dialkyl carbonate in the cyclic carbonate / diol mixture.

[0100] When the reaction of step (I) is carried out industrially, it is preferable that, in addition to the cyclic carbonate and / or aliphatic monohydric alcohol newly introduced into the reaction system, a substance mainly composed of the cyclic carbonate and / or aliphatic monohydric alcohol recovered in this step and / or other steps can be used as the raw material for these. The other steps include, for example, step (II) of producing a diaryl carbonate (e.g., diphenyl carbonate) from a dialkyl carbonate and an aryl alcohol (e.g., phenol), and in this step (II), an aliphatic monohydric alcohol is by-produced and recovered. This recovered by-product aliphatic monohydric alcohol usually contains dialkyl carbonate, aryl alcohol (e.g., phenol), alkyl aryl ether, etc., and may further contain small amounts of alkyl aryl carbonate, diaryl carbonate (e.g., diphenyl carbonate), etc. The by-produced aliphatic monohydric alcohol can be used as the raw material for step (I) as it is, or can be used as the raw material for step (I) after reducing the amount of substances contained therein that have a higher boiling point than the aliphatic monohydric alcohol by distillation or the like.

[0101] In addition, the preferred cyclic carbonate used in step (I) is, for example, one produced by reacting an alkylene oxide such as ethylene oxide, propylene oxide, or styrene oxide with carbon dioxide, and therefore a cyclic carbonate containing a small amount of these compounds can also be used as the raw material in step (I).

[0102] In step (I), the ratio of the amount of the cyclic carbonate and the aliphatic monohydric alcohols to be fed to the reactive distillation column varies depending on the type and amount of the transesterification catalyst and the reaction conditions, but usually, the aliphatic monohydric alcohols can be fed in a molar ratio of 0.01 to 1000 times the amount of the cyclic carbonate to be fed. In order to increase the reaction rate of the cyclic carbonate, it is preferable to feed the aliphatic monohydric alcohols in an excess amount of 2 times or more, but if it is used in too large an excess, it is necessary to make the apparatus larger. In this sense, the molar ratio of the aliphatic monohydric alcohols to the cyclic carbonate is preferably 2 to 20, more preferably 3 to 15, and even more preferably 5 to 12. If a large amount of unreacted cyclic carbonate remains, it reacts with the product diols to produce polymers such as dimers and trimers as by-products, so when carried out industrially, it is preferable to reduce the amount of unreacted cyclic carbonate as much as possible.

[0103] In step (I), for example, when about 0.4 tons or more of dialkyl carbonate is continuously produced per hour, the minimum amount of cyclic carbonate continuously supplied is usually 0.44 P ton / hr, preferably 0.42 P ton / hr, more preferably 0.4 P ton / hr, relative to the amount of dialkyl carbonate to be produced (P ton / hr). In more preferable cases, it can be less than 0.39 P ton / hr.

[0104] The continuous multi-stage distillation column T0 used in step (I) is not particularly limited, but for example, as shown in FIG. 3, has a cylindrical body with a length L0 (cm) and an internal diameter D0 (cm) and has an internal with a number of stages n0 inside, and has an internal with an internal diameter d 01 (cm) gas outlet, at the bottom of the tower or at the bottom of the tower close to it, with an inner diameter of d 02 (cm) of a liquid outlet, one or more first inlets below the gas outlet and at the upper and / or middle part of the column, and one or more second inlets above the liquid outlet and at the middle and / or lower part of the column, 01 , D0 / d 02However, examples of the continuous multi-stage distillation columns include those that satisfy the formulas (1) to (6). 2100≦L0≦8000 Formula (1) 180≦D0≦2000 Formula (2) 4 ≦ L0 / D0≦ 40 Formula (3) 10 ≦ n0 ≦ 120 Equation (4) 3≦D0 / d 01 ≦ 20 Equation (5) 5≦D0 / d 02 ≦ 30 Equation (6).

[0105] In this embodiment, the term "top of the tower or an upper part of the tower close thereto" means a part from the top of the tower downward to about 0.25 L0, and the term "bottom of the tower or a lower part of the tower close thereto" means a part from the bottom of the tower upward to about 0.25 L0. (In the first and second continuous multi-stage distillation towers, these are 0.25 L1 and 0.25 L2, respectively, and in the purification tower A and the diphenyl carbonate purification tower B, these are 0.25 L1 and 0.25 L2, respectively. A and 0.25L B It is.)

[0106] By using a continuous multi-stage distillation column T0 that simultaneously satisfies formulas (1), (2), (3), (4), (5) and (6), it is possible to stably produce dialkyl carbonates from cyclic carbonates and aliphatic monohydric alcohols at an industrial scale of preferably 0.4 tons or more per hour and / or diols at preferably 0.26 tons or more per hour, with high reaction rate, high selectivity and high productivity, for example, for a long period of time of 1000 hours or more, preferably 3000 hours or more, and more preferably 5000 hours or more. The reason why the production of dialkyl carbonates and diols on an industrial scale with such excellent effects is possible by carrying out step (I) is not clear, but it is presumed to be due to the combined effect brought about when the conditions of formulas (1) to (6) are combined. The preferred ranges of each factor are shown below.

[0107] When L0 (cm) is 2100 or more, the reaction rate is good and the desired production amount can be achieved. In order to reduce equipment costs while ensuring a reaction rate that can achieve the desired production amount, it is preferable to set L0 to 8000 or less. A more preferable range of L0 (cm) is 2300≦L0≦6000, and even more preferably 2500≦L0≦5000.

[0108] When D0(cm) is 180 or more, a desired production volume can be achieved. In order to reduce equipment costs while achieving a desired production volume, it is preferable to set D0 to 2000 or less. A more preferable range for D0(cm) is 200≦D0≦1000, and even more preferably, 210≦D0≦800.

[0109] When L0 / D0 is 4 or more or 40 or less, stable operation is facilitated, and in particular, when L0 / D0 is 40 or less, the pressure difference between the top and bottom of the column can be prevented from becoming too large, which not only facilitates long-term stable operation but also makes it possible to lower the temperature in the lower part of the column, suppress side reactions, and tends to improve the selectivity. A more preferred range of L0 / D0 is 5≦L0 / D0≦30, and even more preferably 7≦L0 / D0≦20.

[0110] When n0 is 10 or more, the reaction rate is improved, so that the desired production amount can be achieved. In order to reduce the equipment cost while ensuring the reaction rate that can achieve the desired production amount, it is preferable to set n0 to 120 or less. Furthermore, when n0 is 120 or less, the pressure difference between the top and bottom of the tower can be prevented from becoming too large, which not only facilitates long-term stable operation, but also makes it possible to lower the temperature at the bottom of the tower, suppress side reactions, and tends to improve the selectivity. A more preferable range of n0 is 30≦n0≦100, and even more preferably 40≦n0≦90.

[0111] D0 / d 01When D0 / d is 3 or more, not only can the equipment cost be reduced, but also the outflow of gas components from the system can be suppressed, making stable operation easier. When D0 / d is 20 or less, the amount of gas components drawn off becomes relatively large, making stable operation easier, and the reaction rate tends to improve. 01 The range is 4≦D0 / d 01 ≦15, and more preferably 5≦D0 / d 01 <= 13.

[0112] D0 / d 02 If D0 / d is 5 or more, not only can the equipment cost be reduced, but the amount of liquid drawn off is relatively small, facilitating stable operation, and if it is 30 or less, the flow rate at the liquid drawoff port and piping can be prevented from increasing suddenly, making it difficult for erosion to occur and suppressing corrosion of the equipment. 02 The range is 7≦D0 / d 02 ≦25, and more preferably 9≦D0 / d 02 <= 20.

[0113] Furthermore, the d of the continuous multi-stage distillation column T0 used in step (I) 01 and the d 02 It is even more preferable if and satisfy the formula (28). 1 ≦ d 01 / d 02 ≦ 5 Equation (28).

[0114] The long-term stable operation in step (I) means that the operation can be continued in a steady state based on the operating conditions for 1000 hours or more, preferably 3000 hours or more, and more preferably 5000 hours or more without flooding, clogging or erosion of piping, and predetermined amounts of dialkyl carbonate and diol are produced while maintaining high reaction rate, high selectivity and high productivity.

[0115] The selectivity of the dialkyl carbonate and the diols in step (I) is based on the reacted cyclic carbonate, and in this embodiment, a high selectivity of 95% or more can be achieved, preferably 97% or more, and more preferably 99% or more. The reaction rate in step (I) usually refers to the reaction rate of the cyclic carbonate, and in this embodiment, the reaction rate of the cyclic carbonate can be 95% or more, preferably 97% or more, more preferably 99% or more, even more preferably 99.5% or more, and even more preferably 99.9% or more. One of the excellent features of step (I) is that a high reaction rate can be achieved while maintaining a high selectivity.

[0116] The continuous multi-stage distillation column T0 used in step (I) is preferably a distillation column having trays and / or packings as internals. In this embodiment, the term "internals" refers to the portion of the distillation column where gas and liquid are actually contacted. Such trays are not particularly limited, but are preferably, for example, bubble trays, perforated plate trays, valve trays, countercurrent trays, Superfrac trays, Maxfrac trays, etc., and as packings, random packings such as Raschig rings, Lessing rings, Paul rings, Berl saddles, Intalox saddles, Dixon packing, McMahon packing, and Helipacks, and ordered packings such as Melapacks, Gempacks, Technopacks, Flexipacks, Sulzer packings, Goodroll packings, and Glitch grids are preferably used. A multi-stage distillation column having both a tray portion and a portion filled with packings can also be used. In addition, the term "internal stage number" in this embodiment means the number of trays in the case of trays, and means the theoretical number of stages in the case of packings. Therefore, in the case of a multi-stage distillation column having both a tray section and a section packed with packing, the number of stages is the sum of the number of trays and the theoretical number of stages.

[0117] In step (I) of reacting a cyclic carbonate with an aliphatic monohydric alcohol, whether a plate-type continuous multi-stage distillation column and / or a packed-column-type continuous multi-stage distillation column in which the internal is made of trays and / or packings having a predetermined number of stages is used, a high reaction rate, high selectivity, and high productivity tend to be achieved. A plate-type distillation column in which the internal is a tray is more preferred. Furthermore, a sieve tray having a sieve plate section and a downcomer section is particularly excellent in terms of the relationship between function and equipment costs. And, the sieve tray has a sieve plate section with an area of ​​1 m 2 It is preferable that the number of holes is 100 to 1000 per square meter. More preferable number of holes is 100 to 1000 per square meter. 2 The number of holes in the sieve tray is preferably 120 to 900, and more preferably 150 to 800. The cross-sectional area of ​​each hole in the sieve tray is preferably 0.5 to 5 cm. 2 More preferably, the cross-sectional area per hole is 0.7 to 4 cm. 2 and more preferably 0.9 to 3 cm 2 Furthermore, the sieve tray has a sieve area of ​​1 m 2 It has 100 to 1000 holes per hole, and the cross-sectional area of ​​each hole is 0.5 to 5 cm 2 It is particularly preferred if

[0118] Furthermore, the aperture ratio of the sieve tray is preferably 1.5 to 15%. More preferably, the aperture ratio is 1.7 to 13%, and even more preferably 1.9 to 11%. Here, the aperture ratio of the sieve tray refers to the ratio of the cross-sectional area of ​​all the holes (total hole cross-sectional area) present in the sieve tray to the area of ​​the sieve tray portion (including the total hole cross-sectional area). The area and / or the total hole cross-sectional area of ​​the sieve tray portion may differ in each sieve tray, but even in this case, it is preferable that the aperture ratio of each sieve tray is within the above range. The number of holes in the sieve tray portion may be the same or different in all the sieve trays.

[0119] When carrying out step (I), for example, the raw materials, cyclic carbonate and aliphatic monohydric alcohols, are continuously supplied to a continuous multi-stage distillation column in the presence of a catalyst, and reaction and distillation are simultaneously carried out in the column. The low-boiling reaction mixture containing the produced dialkyl carbonate is continuously withdrawn in a gaseous state from the top of the column, and the high-boiling reaction mixture containing diols is continuously withdrawn in a liquid state from the bottom of the column, thereby continuously producing dialkyl carbonate and diols.

[0120] In step (I), the raw materials, cyclic carbonate and aliphatic monohydric alcohols, can be continuously supplied into the continuous multi-stage distillation column T0 by supplying them in liquid and / or gaseous form as a raw material mixture or separately from one or more inlets located below the gas outlet at the top of the distillation column but in the upper or middle part of the column. Alternatively, it is also a preferred method to supply the cyclic carbonate or a raw material containing a large amount of it in liquid form from an inlet at the upper or middle part of the distillation column and supply the aliphatic monohydric alcohols or a raw material containing a large amount of it in gaseous form from an inlet located above the liquid outlet at the bottom of the distillation column but in the middle or lower part of the column.

[0121] The reaction time of the transesterification reaction carried out in step (I) is considered to correspond to the average residence time of the reaction liquid in the continuous multi-stage distillation column T0. This varies depending on the shape of the internals of the distillation column, the number of stages, the amount of raw material supplied, the type and amount of catalyst, the reaction conditions, etc., but is usually 0.1 to 20 hours, preferably 0.5 to 15 hours, and more preferably 1 to 10 hours.

[0122] The reaction temperature in step (I) varies depending on the type of raw material compound and the type and amount of catalyst used, but is usually 30 to 300°C. It is preferable to increase the reaction temperature in order to increase the reaction rate, but side reactions are more likely to occur when the reaction temperature is high. The preferred reaction temperature is 40 to 250°C, more preferably 50 to 200°C, and even more preferably 60 to 150°C. In this embodiment, it is possible to carry out reactive distillation at a column bottom temperature of 150°C or less, preferably 130°C or less, more preferably 110°C or less, and even more preferably 100°C or less. One of the excellent features of step (I) is that a high reaction rate, high selectivity, and high productivity can be achieved even at such a low column bottom temperature. In addition, the reaction pressure varies depending on the type and composition of the raw material compound used, the reaction temperature, etc., but may be reduced pressure, normal pressure, or increased pressure, and is usually 1 Pa to 2 x 10 7 Pa, preferably 10 3 Pa~10 7 Pa, more preferably 10 4 Pa~5×10 6 It is carried out in the Pa range.

[0123] The reflux ratio of the continuous multi-stage distillation column T0 in the step (I) is usually 0 to 10, preferably 0.01 to 5, and more preferably 0.05 to 3.

[0124] The material constituting the continuous multi-stage distillation column T0 used in step (I) is mainly a metal material such as carbon steel or stainless steel, but from the viewpoint of the quality of the dialkyl carbonate and diols produced, stainless steel is preferred.

[0125] The method for industrially producing a high purity diaryl carbonate of this embodiment includes continuously supplying a dialkyl carbonate and an aryl alcohol into a first continuous multi-stage distillation column in the presence of a catalyst, simultaneously carrying out reaction and distillation in the first continuous multi-stage distillation column, continuously withdrawing a first column low-boiling point reaction mixture containing the produced alcohols in a gaseous state from an upper portion of the first continuous multi-stage distillation column, continuously withdrawing a first column high-boiling point reaction mixture containing the produced alkyl aryl carbonate in a liquid state from a lower portion of the first continuous multi-stage distillation column, and continuously extracting the alkyl aryl carbonate. and continuously supplying the first column high-boiling point reaction mixture into a second continuous multi-stage distillation column in the presence of a catalyst, and simultaneously carrying out reaction and distillation in the second continuous multi-stage distillation column, continuously withdrawing the second column low-boiling point reaction mixture containing the produced dialkyl carbonates in a gaseous state from the top of the second continuous multi-stage distillation column, and continuously withdrawing the second column high-boiling point reaction mixture containing the produced diaryl carbonate in a liquid state from the bottom of the second continuous multi-stage distillation column, thereby continuously producing diaryl carbonate (hereinafter also referred to as "step (II)"). The dialkyl carbonate used in step (II) is not particularly limited, but examples thereof include those represented by the following formula shown in Chemical Formula 1 above. [ka] Here, R 2 is as stated above.

[0126] Such an R 2The dialkyl carbonate having the formula (I) is not particularly limited, but examples thereof include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (each isomer), diallyl carbonate, dibutenyl carbonate (each isomer), dibutyl carbonate (each isomer), dipentyl carbonate (each isomer), dihexyl carbonate (each isomer), diheptyl carbonate (each isomer), dioctyl carbonate (each isomer), dinonyl carbonate (each isomer), didecyl carbonate (each isomer), dicyclopentyl carbonate, ... Examples of the carbonates include cyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (each isomer), di(phenylpropyl) carbonate (each isomer), di(phenylbutyl) carbonate (each isomer), di(chlorobenzyl) carbonate (each isomer), di(methoxybenzyl) carbonate (each isomer), di(methoxymethyl) carbonate, di(methoxyethyl) carbonate (each isomer), di(chloroethyl) carbonate (each isomer), and di(cyanoethyl) carbonate (each isomer).

[0127] Among these, the one preferably used in this embodiment is R 2 is a dialkyl carbonate containing no halogen and having an alkyl group having 4 or less carbon atoms, and dimethyl carbonate is particularly preferred. Among the preferred dialkyl carbonates, more preferred are dialkyl carbonates produced in a state substantially free of halogen, such as those produced from an alkylene carbonate substantially free of halogen and an alcohol substantially free of halogen.

[0128] The phenol used in step (II) is represented by the following general formula, and is a compound in which a hydroxyl group is directly bonded to a phenyl group (Ph). In some cases, a substituted phenol in which the phenyl group is substituted with a lower alkyl group or a lower alkoxy group can also be used: PhOH

[0129] In this embodiment, phenol substantially free of halogen is preferably used. Therefore, diphenyl carbonate in this embodiment is represented by the following general formula: PhOCOOPh

[0130] The molar ratio of dialkyl carbonate to aryl alcohol (e.g., phenol) used as a raw material in step (II) is preferably 0.1 to 10. Within this range, the amount of remaining unreacted raw materials is reduced for a given production amount of the desired diphenyl carbonate, which is efficient and reduces the energy required to recover them. In this sense, the molar ratio is more preferably 0.5 to 5, more preferably 0.8 to 3, and even more preferably 1 to 2.

[0131] In this embodiment, it is preferable to continuously produce 1 ton or more of high purity diaryl carbonate (for example, diphenyl carbonate) per hour.

[0132] Therefore, in step (II), the minimum amount of aryl alcohol (e.g., phenol) continuously supplied is usually 15 tonnes / hr, preferably 13 tonnes / hr, more preferably 10 tonnes / hr, relative to the amount (1 tonnes / hr) of high purity diaryl carbonate (e.g., diphenyl carbonate) to be produced. In more preferable cases, it can be less than 8 tonnes / hr.

[0133] In addition, the dialkyl carbonate and aryl alcohol (e.g., phenol) used as raw materials in step (II) may each be of high purity, but may contain other compounds, for example, compounds and reaction by-products produced in the first and / or second continuous multi-stage distillation columns. When carried out industrially, it is preferable to use, as these raw materials, in addition to the dialkyl carbonate and aryl alcohol (e.g., phenol) newly introduced into the reaction system, those recovered from the first and / or second continuous multi-stage distillation columns. In the method of this embodiment, a first circulation step is performed in which the top component, which is the second column low boiling point reaction mixture in the second continuous multi-stage distillation column, is continuously supplied into the first continuous multi-stage distillation column. In this case, the second column low boiling point reaction mixture may be supplied to the first continuous multi-stage distillation column as it is, or may be supplied after separating a part of the components.

[0134] In this embodiment which is industrially carried out, the raw material supplied to the first continuous multi-stage distillation column preferably contains alcohols, alkylaryl carbonates (e.g., alkylphenyl carbonates), diaryl carbonates (e.g., diphenyl carbonate), alkylaryl ethers (e.g., alkylphenyl ethers), and the like, and further preferably contains a small amount of high-boiling by-products such as Fries rearrangement products of aryl carbonates (e.g., phenyl carbonate) and diaryl carbonates (e.g., diphenyl carbonate) which are the products, and derivatives thereof. In this embodiment, for example, when methylphenyl carbonate and diphenyl carbonate are produced using dimethyl carbonate as the dialkyl carbonate and unsubstituted phenol as the phenol as the raw material, it is preferable that the raw material contains reaction products such as methyl alcohol, methylphenyl carbonate, and diphenyl carbonate, and further may contain a small amount of reaction by-products such as anisole, phenyl salicylate, methyl salicylate, and high-boiling by-products derived from these.

[0135] In addition, the diaryl carbonate (e.g., diphenyl carbonate) obtained by the manufacturing method of this embodiment is preferably used to manufacture an aromatic polycarbonate by polymerization with an aromatic dihydroxy compound, and in this polymerization step, a large amount of aryl alcohol (e.g., phenol) is by-produced and recovered. It is a preferred method to use this by-produced aryl alcohol (e.g., phenol) as a raw material in step (II).

[0136] The diaryl carbonate (e.g., diphenyl carbonate) produced in step (II) is obtained by an ester exchange reaction between a dialkyl carbonate and an aryl alcohol (e.g., phenol). This ester exchange reaction includes a reaction in which one or two alkoxy groups of the dialkyl carbonate are exchanged with alkoxy groups (e.g., phenoxy groups) of the aryl alcohol (e.g., phenol) to release alcohols, and a reaction in which the resulting alkylaryl carbonate (e.g., alkylphenyl carbonate) is converted into a diaryl carbonate (e.g., diphenyl carbonate) and a dialkyl carbonate by a disproportionation reaction, which is an ester exchange reaction between two molecules of the resulting alkylaryl carbonate (e.g., alkylphenyl carbonate). In the first continuous multi-stage distillation column in step (II), mainly alkylaryl carbonate (e.g., alkylphenyl carbonate) is obtained, and in the second continuous multi-stage distillation column, mainly the alkylaryl carbonate (e.g., alkylphenyl carbonate) is disproportionated to obtain diaryl carbonate (e.g., diphenyl carbonate) and dialkyl carbonate. The diaryl carbonate (e.g., diphenyl carbonate) obtained in step (II) is preferably completely free of halogen. Such diaryl carbonate (e.g., diphenyl carbonate) is useful, for example, as a raw material for industrially producing aromatic polycarbonate. This is because, if halogen is present in the polymerization raw material even in an amount less than 1 ppm, it inhibits the polymerization reaction, inhibits stable production of aromatic polycarbonate, and causes a decrease in the physical properties and coloring of the produced aromatic polycarbonate.

[0137] The catalyst used in the first continuous multi-stage distillation column and / or the second continuous multi-stage distillation column in step (II) is not particularly limited, and may be selected from, for example, the following compounds: <Lead compounds> Lead oxides such as PbO, PbO2, Pb3O4; Lead sulfides such as PbS and Pb2S; Lead hydroxides such as Pb(OH)2 and Pb2O2(OH)2; Naphthalites such as Na2PbO2, K2PbO2, NaHPbO2, KHPbO2; Plumbates such as Na2PbO3, Na2H2PbO4, K2PbO3, K2[Pb(OH)6], K4PbO4, Ca2PbO4, and CaPbO3; Lead carbonates and their basic salts such as PbCO3, 2PbCO3·Pb(OH)2; Lead salts of organic acids such as Pb(OCOCH3)2, Pb(OCOCH3)4, Pb(OCOCH3)2·PbO·3H2O, and their carbonates and bases; Organolead compounds such as Bu4Pb, Ph4Pb, Bu3PbCl, Ph3PbBr, Ph3Pb (or Ph6Pb2), Bu3PbOH, and Ph3PbO (Bu stands for butyl and Ph stands for phenyl); Alkoxyleads and aryloxyleads such as Pb(OCH3)2, (CH3O)Pb(OPh), and Pb(OPh)2; Lead alloys such as Pb-Na, Pb-Ca, Pb-Ba, Pb-Sn, Pb-Sb; Lead minerals such as arsenite and arsenite, and hydrates of these lead compounds; <Copper group metal compounds> Salts and complexes of copper group metals such as CuCl, CuCl2, CuBr, CuBr2, CuI, CuI2, Cu(OAc)2, Cu(acac)2, copper oleate, Bu2Cu, (CH3O)2Cu, AgNO3, AgBr, silver picrate, AgC6H6ClO4, [AuC≡CC(CH3)3]n, [Cu(C7H8)Cl]4 (acac stands for acetylacetone chelating ligand); <Alkali metal complexes> Complexes of alkali metals such as Li(acac), LiN(C4H9)2; <Zinc complex> Zinc complexes such as Zn(acac)2; <Cadmium complex> Cadmium complexes such as Cd(acac)2; <Iron group metal compounds> Fe(C 10 Complexes of iron group metals such as H8)(CO)5, Fe(CO)5, Fe(C4H6)(CO)3, Co(mesitylene)2(PEt2Ph)2, CoC5F5(CO)7, Ni-π-C5H5NO, and ferrocene; <Zirconium complex> Zirconium complexes such as Zr(acac)4, zirconocene; <Lewis acid compounds> Lewis acids and transition metal compounds capable of generating Lewis acids, such as AlX3, TiX3, TiX4, VOX3, VX5, ZnX2, FeX3, and SnX4 (wherein X is a halogen, an acetoxy group, an alkoxy group, or an aryloxy group); <Organotin compounds> (CH3)3SnOCOCH3, (C2H5)3SnOCOC6H5, Bu3SnOCOCH3, Ph3SnOCOCH3, Bu2Sn(OCOCH3)2, Bu2Sn(OCOC 11 H 23 )2, Ph3SnOCH3, (C2H5)3SnOPh, Bu2Sn(OCH3)2, Bu2Sn(OC2H5)2, Bu2Sn(OPh)2, Ph2Sn(OCH3)2, (C2H5)3SnOH, Ph3SnOH, Bu2SnO, (C8H 17 )2SnO, Bu2SnCl2, BuSnO(OH), and other organotin compounds; Metal-containing compounds such as the above are used as catalysts.

[0138] The catalyst used in this embodiment is preferably one containing metals such as Pb, Cu, Zn, Fe, Co, Ni, Al, Ti, V, Sn, etc., and is a homogeneous catalyst that dissolves in the reaction system. Therefore, a catalyst species in which these metal components are bonded to an organic group is preferably used. Of course, these catalyst components may be reacted with organic compounds present in the reaction system, such as aliphatic alcohols, phenols, alkylphenyl carbonates, diphenyl carbonates, dialkyl carbonates, etc., or may be heat-treated with raw materials or products prior to the reaction. The catalyst used in this embodiment is preferably one that has high solubility in the reaction liquid under the reaction conditions. In this sense, preferred catalysts include, for example, PbO, Pb(OH)2, Pb(OPh)2; TiCl4, Ti(OMe)4, (MeO)Ti(OPh)3, (MeO)2Ti(OPh)2, (MeO)3Ti(OPh), Ti(OPh)4; SnCl4, Sn(OPh)4, Bu2SnO, Bu2Sn(OPh)2; FeCl3, Fe(OH)3, Fe(OPh)3, etc., or those treated with phenol or a reaction liquid, etc. The catalyst used in the first continuous multi-stage distillation column and the catalyst used in the second continuous multi-stage distillation column may be the same type or different types.

[0139] In this embodiment, it is particularly preferable to use raw materials and catalysts that do not contain halogens, and in this case, the diaryl carbonate (e.g., diphenyl carbonate) produced does not contain any halogens at all, and is therefore useful as a raw material when industrially producing polycarbonate by the transesterification method. This is because, if halogens are present in the polymerization raw materials even in an amount less than 1 ppm, they can inhibit the polymerization reaction, reduce the physical properties of the produced polycarbonate, or cause coloration.

[0140] The first continuous multi-stage distillation column used in step (II) has a cylindrical body having a length L1 (cm) and an internal diameter D1 (cm) and has an internal having a number of stages n1 therein, as shown in FIG. 4, for example. 11(cm) gas outlet, at the bottom of the tower or at the bottom of the tower close to it, with an inner diameter of d 12 (cm) of a liquid outlet, one or more third inlets below the gas outlet and in the upper and / or middle part of the column, and one or more fourth inlets above the liquid outlet and in the middle and / or lower part of the column, 11 , D1 / d 12 are preferably continuous multi-stage distillation columns satisfying the following formulas (7) to (12), respectively. 1500 ≦ L1 ≦ 8000 Formula (7) 100≦D1≦2000 Formula (8) 2 ≦ L1 / D1≦ 40 Formula (9) 20 ≦ n1 ≦ 120 Equation (10) 5 ≦ D1 / d 11 ≦ 30 Equation (11) 3 ≦ D1 / d 12 ≦ 20 Equation (12)

[0141] The second continuous multi-stage distillation column used in step (II) has a cylindrical body having a length L2 (cm) and an internal diameter D2 (cm) and has an internal having a number of stages n2 therein, as shown in FIG. 5, and has an internal having an internal diameter d 21 (cm) gas outlet, at the bottom of the tower or at the bottom of the tower close to it, with an inner diameter of d 22 (cm) of a liquid outlet, one or more fifth inlets below the gas outlet and at the upper and / or middle part of the column, and one or more sixth inlets above the liquid outlet and at the middle and / or lower part of the column, 21 , D2 / d 22 are preferably continuous multi-stage distillation columns satisfying the following formulas (13) to (18), respectively. 1500 ≦ L2 ≦ 8000 Formula (13) 100≦D2≦2000 Formula (14) 2 ≦ L2 / D2≦ 40 Equation (15) 10 ≦ n2 ≦ 80 Equation (16) 2 ≦ D2 / d 21 ≦ 15 Equation (17) 5 ≦ D2 / d 22 ≦ 30 Equation (18)

[0142] By using the first and second continuous multi-stage distillation columns which simultaneously satisfy all of the formulas (7) to (18), diaryl carbonate (e.g., diphenyl carbonate) can be stably produced from dialkyl carbonate and aryl alcohol (e.g., phenol) at an industrial scale of 0.5 tons or more, preferably 1 ton or more per hour, with high selectivity and high productivity, for example, for a long period of time of 2000 hours or more, preferably 3000 hours or more, and more preferably 5000 hours or more. The reason why it is possible to produce aromatic carbonate on an industrial scale with such excellent effects is not clear, but it is presumed to be due to the combined effect brought about when the conditions of the formulas (7) to (18) are combined. The preferred ranges of each factor constituting the continuous multi-stage distillation column used in step (II) are shown below.

[0143] When L1 (cm) and L2 (cm) are each 1500 or more, the reaction rate is improved and the desired production amount can be achieved. In order to reduce equipment costs while ensuring a reaction rate that can achieve the desired production amount, it is preferable that L1 and L2 are each 8000 or less. More preferable ranges of L1 (cm) and L2 (cm) are 2000≦L1≦6000 and 2000≦L2≦6000, respectively, and even more preferable ranges are 2500≦L1≦5000 and 2500≦L2≦5000, respectively.

[0144] When D1 (cm) and D2 (cm) are each 100 or more, a desired production volume can be achieved. In order to achieve a desired production volume while reducing equipment costs, it is preferable that D1 and D2 are each 2000 or less. More preferable ranges of D1 (cm) and D2 (cm) are 150≦D1≦1000 and 150≦D2≦1000, respectively, and even more preferable ranges are 200≦D1≦800 and 200≦D2≦800, respectively.

[0145] In the first and second continuous multi-stage distillation columns, as long as D1 and D2 are within the above ranges, the inner diameters may be the same from the top to the bottom of the column, or the inner diameters may differ partially. For example, in these continuous multi-stage distillation columns, the inner diameter of the top of the column may be smaller or larger than the inner diameter of the bottom of the column.

[0146] When L1 / D1 and L2 / D2 are 2 or more or 40 or less, respectively, stable operation is facilitated, and when they are 40 or less in particular, the pressure difference between the top and bottom of the tower can be prevented from becoming too large, which not only facilitates long-term stable operation but also allows the temperature in the lower part of the tower to be lowered, which inhibits side reactions and tends to improve the selectivity. More preferred ranges of L1 / D1 and L2 / D2 are 3≦L1 / D1≦30 and 3≦L2 / D2≦30, respectively, and even more preferred ranges are 5≦L1 / D1≦15 and 5≦L2 / D2≦15.

[0147] When n1 is 20 or more, the reaction rate is improved, so that the desired production amount can be achieved in the first continuous multi-stage distillation column. In addition, in order to reduce equipment costs while ensuring a reaction rate that can achieve the desired production amount, it is preferable to set n1 to 120 or less. Furthermore, when n1 is 120 or less, the pressure difference between the top and bottom of the column can be prevented from becoming too large, which not only facilitates long-term stable operation of the first continuous multi-stage distillation column, but also allows the temperature at the bottom of the column to be lowered, which tends to suppress side reactions and improve selectivity. A more preferable range of n1 is 30≦n1≦100, and even more preferably 40≦n1≦90.

[0148] In addition, when n2 is 10 or more, the reaction rate is improved, so that the desired production amount can be achieved in the second continuous multi-stage distillation column. In order to reduce equipment costs while ensuring a reaction rate that can achieve the desired production amount, it is preferable to set n2 to 80 or less. Furthermore, when n2 is 80 or less, the pressure difference between the top and bottom of the column can be prevented from becoming too large, which not only facilitates long-term stable operation of the second continuous multi-stage distillation column, but also allows the temperature at the bottom of the column to be low, which tends to suppress side reactions and improve selectivity. A more preferable range of n2 is 15≦n2≦60, and even more preferably 20≦n2≦50.

[0149] D1 / d 11 When D1 / d is 5 or more, the equipment cost of the first continuous multi-stage distillation column can be reduced and the leakage of gas components out of the system can be suppressed, facilitating stable operation of the first continuous multi-stage distillation column. When D1 / d is 30 or less, the amount of gas components extracted becomes relatively large, facilitating stable operation and also tending to improve the reaction rate. 11 The range is 8≦D1 / d 11 ≦25, and more preferably 10≦D1 / d 11 ≦20. Also, D2 / d 21 When D2 / d is 2 or more, the equipment cost of the second continuous multi-stage distillation column can be reduced, and the gas components can be prevented from escaping from the system, which facilitates stable operation of the second continuous multi-stage distillation column. When D2 / d is 15 or less, the amount of gas components extracted becomes relatively large, which not only facilitates stable operation but also tends to improve the reaction rate. 21 The range is 5≦D2 / d 21 ≦12, and more preferably 3≦D2 / d 21 <= 10.

[0150] D1 / d 12 When D1 / d is 3 or more, the equipment cost of the first continuous multi-stage distillation column can be reduced, the amount of liquid withdrawn is relatively small, and stable operation of the first continuous multi-stage distillation column can be facilitated. When D1 / d is 20 or less, a sudden increase in the flow rate at the liquid withdrawal port and piping can be prevented, and erosion is less likely to occur, thereby suppressing corrosion of the equipment. 12The range is 5≦D1 / d 12 ≦18, and more preferably 7≦D1 / d 12 ≦15. Also, D2 / d 22 When D2 / d is 5 or more, the equipment cost of the second continuous multi-stage distillation column can be reduced, the amount of liquid withdrawn is relatively small, and stable operation of the second continuous multi-stage distillation column can be easily achieved. When D2 / d is 30 or less, a sudden increase in the flow rate at the liquid withdrawal port and piping can be prevented, and erosion is less likely to occur, thereby suppressing corrosion of the equipment. 22 The range is 7≦D2 / d 22 ≦25, and more preferably 9≦D2 / d 22 <= 20.

[0151] Further, in step (II), 11 and the d 12 and satisfy the formula (29), and 21 and the d 22 It is even more preferable if satisfies equation (30). 1≦d 12 / d 11 ≦5 Equation (29) 1≦d 21 / d 22 ≦6 Formula (30)

[0152] The long-term stable operation in step (II) means that operation can be continued in a steady state based on the operating conditions for 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more, without flooding, weeping, clogging or erosion of piping, and the like, and a predetermined amount of diaryl carbonate (e.g., diphenyl carbonate) is produced while maintaining high selectivity.

[0153] In step (II), the diaryl carbonate (e.g., diphenyl carbonate) is produced stably for a long period of time with high selectivity and high productivity of preferably 1 ton or more per hour, more preferably 2 tons or more per hour, and even more preferably 3 tons or more per hour. In step (II), the L1, D1, L1 / D1, n1, and D1 / d of the first continuous multi-stage distillation column are11 , D1 / d 12 are 2000≦L1≦6000, 150≦D1≦1000, 3≦L1 / D1≦30, 30≦n1≦100, and 8≦D1 / d 11 ≦25, 5≦D1 / d 12 ≦18, and L2, D2, L2 / D2, n2, and D2 / d of the second continuous multi-stage distillation column 21 , D2 / d 22 are 2000≦L2≦6000, 150≦D2≦1000, 3≦L2 / D2≦30, 15≦n2≦60, and 2.5≦D2 / d 21 ≦12, 7≦D2 / d 22 If ≦25, then it is to produce 2 tons or more of diaryl carbonate (eg, diphenyl carbonate) per hour, preferably 2.5 tons or more per hour, more preferably 3 tons or more per hour.

[0154] Further, in the step (II), L1, D1, L1 / D1, n1, and D1 / d of the first continuous multi-stage distillation column are 11 , D1 / d 12 are 2500≦L1≦5000, 200≦D1≦800, 5≦L1 / D1≦15, 40≦n1≦90, and 10≦D1 / d 11 ≦25, 7≦D1 / d 12 ≦15, and L2, D2, L2 / D2, n2, and D2 / d of the second continuous multi-stage distillation column 21 , D2 / d 22 are 2500≦L2≦5000, 200≦D2≦800, 5≦L2 / D2≦10, 20≦n2≦50, and 3≦D2 / d 21 ≦10, 9≦D2 / d 22 If ≦20, it is to produce 3 tons or more of diaryl carbonate (eg, diphenyl carbonate) per hour, preferably 3.5 tons or more per hour, more preferably 4 tons or more per hour.

[0155] The selectivity of diaryl carbonate (e.g., diphenyl carbonate) in step (II) refers to the selectivity relative to the reacted aryl alcohol (e.g., phenol), and in step (II), a high selectivity of usually 95% or more can be achieved, preferably 97% or more, and more preferably 98% or more.

[0156] The first and second continuous multi-stage distillation columns used in step (II) are preferably distillation columns having trays and / or packings as internals. In this embodiment, the internals refer to the portion of the distillation column where gas and liquid are actually contacted. Such trays are preferably those described in step (I). The "number of internal stages" is as defined above.

[0157] In the first continuous multi-stage distillation column in step (II), a reaction is carried out mainly to produce an alkylaryl carbonate (e.g., alkylphenyl carbonate) from a dialkyl carbonate and phenol. Since this reaction has an extremely small equilibrium constant and a slow reaction rate, a plate-type distillation column with a tray as the internal is more preferable as the first continuous multi-stage distillation column used for reactive distillation. In addition, in the second continuous multi-stage distillation column, a reaction is mainly carried out to disproportionate the alkylaryl carbonate (e.g., alkylphenyl carbonate). This reaction also has a small equilibrium constant and a slow reaction rate. However, as the second continuous multi-stage distillation column used for reactive distillation, a distillation column with both packings and trays as the internal is more preferable. Furthermore, as the second continuous multi-stage distillation column, one with packings installed at the top and trays installed at the bottom is preferable. The packing of the second continuous multi-stage distillation column is preferably structured packing, and among structured packings, Melapack is particularly preferable.

[0158] Furthermore, the trays installed in the first continuous multi-stage distillation column and the second continuous multi-stage distillation column are particularly excellent in terms of the relationship between function and equipment costs when the trays have a sieve section and a downcomer section. 2It is preferable that the number of holes is 100 to 1000 per square meter. More preferable number of holes is 100 to 1000 per square meter. 2 The number of particles per unit area is preferably 120 to 900, and more preferably 150 to 800.

[0159] The cross-sectional area of ​​each hole in the perforated tray is 0.5 to 5 cm 2 More preferably, the cross-sectional area per hole is 0.7 to 4 cm. 2 and more preferably 0.9 to 3 cm 2 Furthermore, the sieve tray has a sieve area of ​​1 m 2 It has 100 to 1000 holes per hole, and the cross-sectional area of ​​each hole is 0.5 to 5 cm 2 It is particularly preferred if

[0160] When carrying out step (II), the raw materials, dialkyl carbonate and aryl alcohol (e.g., phenol), are continuously supplied to a first continuous multi-stage distillation column in the presence of a catalyst, reaction and distillation are carried out simultaneously in the first continuous multi-stage distillation column, the first column low-boiling reaction mixture containing the produced alcohols is continuously withdrawn in a gaseous state from the top of the first continuous multi-stage distillation column, and the first column high-boiling reaction mixture containing the produced alkyl aryl carbonate (e.g., alkyl phenyl carbonate) is continuously withdrawn in a liquid state from the bottom of the first continuous multi-stage distillation column. The first column high-boiling point reaction mixture is continuously supplied to a second continuous multi-stage distillation column in the presence of a catalyst, and reaction and distillation are carried out simultaneously in the second continuous multi-stage distillation column. The second column low-boiling point reaction mixture containing the produced dialkyl carbonates is continuously withdrawn in gaseous form from the top of the second continuous multi-stage distillation column, and the second column high-boiling point reaction mixture containing the produced diaryl carbonate (e.g., diphenyl carbonate) is continuously withdrawn in liquid form from the bottom of the second continuous multi-stage distillation column, thereby continuously producing diaryl carbonate (e.g., diphenyl carbonate).

[0161] As described above, the raw material may contain reaction by-products such as alcohols, alkylaryl carbonates (e.g., alkylphenyl carbonates), diaryl carbonates (e.g., diphenyl carbonates), alkylaryl ethers (e.g., alkylphenyl ethers), and high-boiling compounds. Considering the equipment and costs required for separation and purification in other steps, in the case of this embodiment which is actually carried out industrially, it is preferable that the raw material contains small amounts of these compounds.

[0162] The top component of the first continuous multi-stage distillation column in step (II) usually contains dialkyl carbonate, aryl alcohol (e.g., phenol), alkylaryl ether, etc. in addition to the alcohols produced in the reaction, and may further contain small amounts of alkylaryl carbonate, diaryl carbonate (e.g., diphenyl carbonate), etc. This top component of the first continuous multi-stage distillation column can be used as it is as the aliphatic monohydric alcohol in step (I), but it is preferable to use it as the raw material for step (I) after reducing the amount of substances contained that have a boiling point higher than that of the produced alcohol by distillation or the like. It is particularly preferable to use a mixture of the alcohol and dialkyl carbonate as the aliphatic monohydric alcohol in step (I).

[0163] In step (II), the raw materials dialkyl carbonate and aryl alcohol (e.g., phenol) can be continuously supplied into the first continuous multi-stage distillation column in liquid and / or gaseous form from one or several inlets located below the gas outlet at the top of the first distillation column but in the upper or middle part of the column. Alternatively, it is also a preferred method to supply a raw material containing a large amount of aryl alcohol (e.g., phenol) in liquid form from an inlet at the top of the first distillation column, and supply a raw material containing a large amount of dialkyl carbonate in gaseous form from an inlet located above the liquid outlet at the bottom of the first distillation column but in the lower part of the column.

[0164] In step (II), the first column high-boiling reaction mixture containing alkylaryl carbonate (e.g., alkylphenyl carbonate) continuously extracted from the bottom of the first continuous multi-stage distillation column is continuously supplied to the second continuous multi-stage distillation column, and the supply position is lower than the gas outlet at the top of the second continuous multi-stage distillation column, but it is preferable to supply in liquid and / or gaseous form from one or several inlets installed at the top or middle part of the column. In addition, when a distillation column having a packing part at the top and a tray part at the bottom, which is a preferred embodiment of this embodiment, is used as the second continuous multi-stage distillation column, it is preferable that at least one of the inlets is installed between the packing part and the tray part. In addition, when the packing is composed of two or more structured packings, it is also a preferred method to install an inlet at the interval constituting these structured packings.

[0165] In addition, in step (II), it is also a preferred method to condense the overhead gas components of the first and second continuous multi-stage distillation columns and then return a portion of the components to the top of each distillation column through a reflux operation. In this case, the reflux ratio of the first continuous multi-stage distillation column is 0 to 10, and the reflux ratio of the second continuous multi-stage distillation column is in the range of 0.01 to 10, preferably 0.08 to 5, and more preferably 0.1 to 2. In the first continuous multi-stage distillation column, a reflux ratio of 0, in which no reflux operation is performed, is also a preferred embodiment.

[0166] In step (II), any method may be used to make the homogeneous catalyst present in the first continuous multi-stage distillation column, but it is preferable to supply the catalyst into the distillation column from a position above the middle part of the first continuous multi-stage distillation column. It is also preferable to supply the catalyst so that the reaction liquid contacts the catalyst in at least 7 stages, preferably 10 stages, and more preferably 15 stages of the first continuous multi-stage distillation column. In this case, the catalyst solution dissolved in the raw material or the reaction liquid may be introduced together with the raw material, or the catalyst solution may be introduced from an inlet separate from the raw material. In this embodiment, the amount of the catalyst used in the first continuous multi-stage distillation column varies depending on the reaction conditions such as the type of catalyst used, the type and amount ratio of the raw material, the reaction temperature, and the reaction pressure, but is usually used in an amount of 0.0001 to 30 mass%, preferably 0.0005 to 10 mass%, and more preferably 0.001 to 1 mass%, expressed as a ratio to the total mass of the raw materials.

[0167] In step (II), any method may be used to make the homogeneous catalyst present in the second continuous multi-stage distillation column, but it is preferable to supply the catalyst to the distillation column from a position above the middle of the second continuous multi-stage distillation column. In this case, the catalyst solution dissolved in the raw material or the reaction liquid may be introduced together with the raw material, or the catalyst solution may be introduced from an inlet separate from the raw material. In this embodiment, the amount of the catalyst used in the second continuous multi-stage distillation column varies depending on the reaction conditions such as the type of catalyst used, the type and amount ratio of the raw material, the reaction temperature, and the reaction pressure, but is usually used in an amount of 0.0001 to 30% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.001 to 1% by mass, expressed as a ratio to the total mass of the raw materials.

[0168] In step (II), the catalyst used in the first continuous multi-stage distillation column and the catalyst used in the second continuous multi-stage distillation column may be the same or different, but preferably, the same type of catalyst is used. More preferably, the catalyst is the same type and can be dissolved in both reaction liquids. In this case, the catalyst is usually dissolved in the high-boiling point reaction mixture of the first continuous multi-stage distillation column, and is extracted from the bottom of the first distillation column together with alkyl aryl carbonate (e.g., alkyl phenyl carbonate), etc., and is supplied directly to the second continuous multi-stage distillation column, which is a preferred embodiment. It is also possible to add a new catalyst to the second continuous multi-stage distillation column as necessary.

[0169] The reaction time of the transesterification reaction carried out in step (II) is considered to correspond to the average residence time of the reaction liquid in each of the first and second continuous multi-stage distillation columns. This reaction time varies depending on the shape and number of stages of the internals of each of the distillation columns, the amount of raw material supplied, the type and amount of catalyst, reaction conditions, etc., but is usually 0.01 to 10 hours, preferably 0.05 to 5 hours, and more preferably 0.1 to 3 hours in each of the first and second continuous multi-stage distillation columns.

[0170] The reaction temperature of the first continuous multi-stage distillation column varies depending on the type of raw material compound and the type and amount of catalyst used, but is usually in the range of 100 to 350°C. In order to increase the reaction rate, it is preferable to increase the reaction temperature, but a high reaction temperature is undesirable because it makes side reactions more likely to occur, and increases the amount of by-products such as alkyl aryl ethers (e.g., alkyl phenyl ethers). In this sense, the reaction temperature in the first continuous multi-stage distillation column is preferably in the range of 130 to 280°C, more preferably 150 to 260°C, and even more preferably 180 to 250°C.

[0171] The reaction temperature of the second continuous multi-stage distillation column varies depending on the type of raw material compound and the type and amount of catalyst used, but is usually in the range of 100 to 350 ° C. In order to increase the reaction rate, it is preferable to increase the reaction temperature, but if the reaction temperature is high, side reactions are more likely to occur, and it is not preferable because the by-products such as alkyl aryl ethers (e.g., alkyl phenyl ethers), Fries rearrangement reaction products of alkyl aryl carbonates (e.g., alkyl phenyl carbonates) and diaryl carbonates (e.g., diphenyl carbonates) as raw materials and products and their derivatives increase. In this sense, the preferred reaction temperature in the second continuous multi-stage distillation column is in the range of 130 to 280 ° C, more preferably 150 to 260 ° C, and even more preferably 180 to 250 ° C.

[0172] The reaction pressure of the first continuous multi-stage distillation column varies depending on the type and composition of the raw material compounds used, the reaction temperature, etc., but the first continuous multi-stage distillation column may be operated at reduced pressure, normal pressure, or elevated pressure. The column top pressure is usually 0.1 Pa to 2×10 7 Pa, preferably 10 5 Pa~10 7 Pa, more preferably 2×10 5 Pa~5×10 6 The range is Pa.

[0173] The reaction pressure of the second continuous multi-stage distillation column varies depending on the type and composition of the raw material compounds used, the reaction temperature, etc., but may be reduced pressure, normal pressure, or pressurized pressure. The column top pressure is usually 0.1 Pa to 2 × 10 7 Pa, preferably 10 3 Pa~10 6 Pa, more preferably 5×10 3 Pa~10 5 The range is Pa.

[0174] In addition, two or more distillation columns can be used as the first continuous multi-stage distillation column in step (II). In this case, two or more distillation columns can be connected in series, in parallel, or in a combination of series and parallel. In addition, two or more distillation columns can be used as the second continuous multi-stage distillation column in step (II). In this case, two or more distillation columns can be connected in series, in parallel, or in a combination of series and parallel.

[0175] The materials constituting the first continuous multi-stage distillation column and the second continuous multi-stage distillation column used in step (II) are mainly metal materials such as carbon steel and stainless steel, with stainless steel being preferred from the viewpoint of the quality of the aromatic carbonate produced. It is also preferable that the liquid-contacting part at the lower part of the second continuous multi-stage distillation column is made of a material mainly composed of Fe and containing 2 mass % or more of Mo and 18 mass % or less of Cr. If such a material is used for the liquid-contacting part at the lower part of the second continuous multi-stage distillation column, corrosion of the distillation column tends to be suppressed even if the concentration of high-boiling point substances in the components at the lower part of the second continuous multi-stage distillation column is increased. In this embodiment, the term "main component" means 50% by mass or more. EXAMPLES

[0176] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0177] [Analysis method] The concentrations of diphenyl carbonate (DPC), high boiling point materials (HB) and catalyst in the column bottom component, the concentration of alkylaryl carbonate in the low boiling point reaction mixture, the purity of diphenyl carbonate, the content of impurities, and other compositions were analyzed by gas chromatography. The analysis by gas chromatography was performed by the internal standard method, and toluene was used as the internal standard. Equipment: Agilent 7890A Column: Agilent J&W DB-1 (Length 30m x ID 0.25mm x Film 0.25μm) Carrier gas: He Flow rate 2.0 mL / min Inlet temperature: 250℃ Injection volume: 1.0μL Oven temperature: 50°C for 2 minutes, then increase the temperature to 300°C at a rate of 10°C / min and hold for 8 minutes. Injection method: split method, split ratio 20 Detector: FID Temperature 300℃ 0.1 g of the sampled bottom component (Ab) was weighed, and 0.04 g (each weighed to an accuracy of 0.1 mg) was added to 5 mL of acetonitrile to prepare a sample solution for gas chromatography. The adjusted solution was filtered through a 0.45-0.50 μm polytetrafluoroethylene (PTFE) membrane filter. The relationship between the peak area ratio and concentration ratio of DPC and the internal standard (toluene) was obtained by measuring the concentrations of DPC and toluene, which were known in advance, and the gas chromatography measurement value of the bottom component was corrected. The remaining amount [mass %] obtained by subtracting the DPC concentration [mass %] obtained by gas chromatography measurement from 100 [mass %] is the amount of high boiling point substance (HB) and catalyst. The catalyst concentration was measured by decomposing the organic matter in the column bottom component (Ab) using microwaves, measuring the metal concentration (mass%) of the catalyst using an inductively coupled plasma (ICP) emission spectrometer, and calculating the catalyst amount (mass%) from the molecular weight of the catalyst.

[0178] <Example 1> A mixture containing diaryl carbonate (diphenyl carbonate) was produced as follows using the same apparatus and production method as in Example 1 of WO 2007 / 69529, except that the catalyst used in the <reactive distillation> in step (II) of (2) continuously producing diphenyl carbonate was changed to the catalyst described in Example 1 of WO 2011 / 105442. (Preparation of titanium-containing composition) A 60 L batch reactor equipped with a stirrer, a heater, and a distillation column was charged with 7 kg of tetrabutoxytitanium (manufactured by DuPont, product name: Tyzor TnBT) under a nitrogen atmosphere, and then 14 kg of phenol that had been previously purified by distillation was charged. Next, the mixture in the batch reactor was heated to 180°C by a heater at normal pressure and reacted. The n-butanol generated by the reaction was recovered from the top of the distillation column. The batch reactor was then depressurized to about 53 kPa, and the n-butanol was recovered. Thereafter, the batch reactor was returned to normal pressure, about 18 kg of diphenyl carbonate was charged, and the mixture in the reactor was heated to about 190°C. Next, the batch reactor was depressurized to about 1.3 kPa, and diphenyl carbonate containing low boiling point components was distilled off to obtain a titanium-containing composition. Diphenyl carbonate was added so that the titanium concentration of the obtained titanium-containing composition was 5 mass%. The titanium-containing composition was heated at 200°C for about 48 hours, and then used as a reaction catalyst in the subsequent production of diphenyl carbonate. <First continuous multi-stage distillation column 101> The first continuous multi-stage distillation column was constructed as shown in FIG. 3 with L1 = 3300 cm, D1 = 500 cm, L1 / D1 = 6.6, n1 = 80, and D1 / d 11 =17, D1 / d 12 In this example, a continuous multi-stage distillation column with a cross-sectional area of ​​about 1.5 cm per hole was used as the internal. 2 , Number of holes = approx. 250 pieces / m 2 A perforated tray having a hole was used. <Second continuous multi-stage distillation column 201> The second continuous multi-stage distillation column is configured as shown in FIG. 4 with L2 = 3100 cm, D2 = 500 cm, L2 / D2 = 6.2, n2 = 30, and D2 / d 21 A continuous multi-stage distillation column with a theoretical cross-sectional area of ​​about 1.3 cm per hole was used in this example. 2 , Number of holes = approx. 250 pieces / m 2A porous tray having a Mo content of 2.5% by mass and a Cr content of 17% by mass was used for the lower liquid-contacting portion. Test pieces, Test Piece 1 containing no Mo and 19% Cr by mass, and Test Piece 2 containing 0.15% Mo and 0.4% Cr by mass, were placed in the lower liquid-contacting portion. <Production of diphenyl carbonate> Diphenyl carbonate was produced using an apparatus in which a first continuous multi-stage distillation column 101 and a second continuous multi-stage distillation column 201 were connected as shown in FIG. Raw material 1 consisting of phenol / dimethyl carbonate = 1.9 (mass ratio) was continuously introduced in liquid form from the upper inlet 11 of the first continuous multi-stage distillation column 101 at a flow rate of 57 tons / hr. Meanwhile, raw material 2 consisting of dimethyl carbonate / phenol = 3.6 (mass ratio) was continuously introduced in gas form from the lower inlet 12 of the first continuous multi-stage distillation column 101 at a flow rate of 57 tons / hr. The molar ratio of the raw materials introduced into the first continuous multi-stage distillation column 101 was dimethyl carbonate / phenol = 1.35. As a catalyst, the titanium-containing composition prepared above was continuously introduced into the upper inlet 11 of the first continuous multi-stage distillation column 101 at a flow rate of 188 kg / hr from the bottom 11 of the purification column A so that the titanium-containing composition was about 100 ppm in the liquid of the first continuous multi-stage distillation column 101. In the first continuous multi-stage 101, the temperature of the column bottom was 225 ° C., and the pressure of the column top was 7 × 10 5 Reactive distillation was continuously carried out under conditions of a pressure of 100 Pa and a reflux ratio of 0. The first column low boiling point reaction mixture of the first continuous multi-stage distillation column 101 containing methyl alcohol, dimethyl carbonate, phenol, etc. was continuously extracted in a gaseous state from the column top 13, passed through a heat exchanger 14, and extracted from an extraction port 16 at a flow rate of 39 tons / hr. On the other hand, the first column high boiling point reaction mixture of the first continuous multi-stage distillation column 101 containing methyl phenyl carbonate, dimethyl carbonate, phenol, diphenyl carbonate, a catalyst, etc. was continuously extracted in a liquid state from an inlet 21 through a column bottom 17. After 24 hours, a stable steady state was reached, and the first column high boiling point reaction mixture from the column bottom 17 of the first continuous multi-stage distillation column 101 was continuously supplied as it was to the second continuous multi-stage distillation column 201 from the raw material inlet 21 installed between the Melapack and the perforated plate tray at a flow rate of 75 tons / hr. In the second continuous multi-stage distillation column 201, the titanium-containing composition prepared above was present as a catalyst, and the temperature at the column bottom was 210° C., the pressure at the column top was 3×10 4 Reactive distillation was continuously performed under the conditions of 0.2 Pa and a reflux ratio of 0.3. Stable steady-state operation was achieved after 24 hours. A second tower low boiling point reaction mixture containing 35% by mass of dimethyl carbonate, 56% by mass of phenol, and 0.5% by mass of methyl phenyl carbonate was continuously extracted from the top 23 of the second continuous multi-stage distillation column 201, and the flow rate at the extraction port 26 was 62 tons / hr, and a second tower high boiling point reaction mixture containing 38% by mass of methyl phenyl carbonate and 56% by mass of diphenyl carbonate was continuously extracted from the bottom 27 of the column. The second tower low boiling point reaction mixture of the second continuous multi-stage distillation column 201 was continuously supplied from the inlet 11 to the first continuous multi-stage distillation column 101 (first circulation step). At this time, the amount of dimethyl carbonate and phenol newly supplied was adjusted so as to maintain the composition and amount of the above-mentioned raw material 1 and raw material 2, taking into consideration the composition and amount of the second tower low boiling point reaction mixture. <Purification of diphenyl carbonate> FIG. 1 is a process flow schematic diagram of the diphenyl carbonate purification method used in Example 1. In FIG. 1, the left diagram is purification column A, and the right diagram is diaryl carbonate (diphenyl carbonate) purification column B. In FIG. 1, 14 is the top heat exchanger (condenser) of purification column A, 18 is the heat exchanger (reboiler) of purification column A, and similarly, 24 is the top heat exchanger (condenser) of purification column B, and 28 is the heat exchanger (reboiler) of purification column B. The reboiler type of purification column A was a forced circulation type, and the reboiler type of purification column B was a thermosiphon type. In addition, the packings of purification columns A and B were structured packings, the structured packing of purification column A was Mellapak (Mellapak (manufactured by Sulzer)), and the structured packing of purification column B was Mellapak (Mellapak (manufactured by Sulzer)). In Example 1, purification column A was made of stainless steel, had 19 theoretical plates, and had a side cut outlet A2. In purification column A, the side cut outlet A2 was located at the fourth theoretical plate from the top. In purification column A, crude ethylene carbonate was introduced from the column bottom A1. Purification column B was made of stainless steel, had 20 theoretical plates, and had a side cut outlet B2. In purification column B, the column bottom component (Ab) of purification column A was introduced from the fifth theoretical plate from the top. In purification column B, the side cut outlet B2 was located at the 18th theoretical plate from the top. It was continuously introduced at 26,300 kg / hour into the inlet A1 of the purification column A. In the introduction liquid (second column high boiling point reaction mixture) continuously introduced into the purification column A, the content of diphenyl carbonate (DPC) was 56 mass%, the content of methyl phenyl carbonate (MPC) was 26 mass%, the content of high boiling point components was 13 mass%, and the content of catalyst components was 1 mass%. The withdrawal rate of the low boiling point component (top component (At)) from the top 16 of the purification column A was 6800 kg / hour. The circulation rate of the catalyst component (bottom component (Ab)) from the bottom 17 of the purification column A was 5380 kg / hour. At the side cut outlet A2 of the purification column A, the side cut component (As) containing diphenyl carbonate was withdrawn at a rate of 14100 kg / hour and introduced into the purification column B. In the purification column B, the withdrawal rate of the low boiling point component (top component (Bt)) from the top 26 was 1200 kg / hour, and the withdrawal rate of the high boiling point component (bottom component (Bb)) from the bottom 27 was 900 kg / hour. In the purification column B, diphenyl carbonate was withdrawn as the side cut component (Bs) from the side cut outlet B2 at a rate of 12000 kg / hour (production amount (BsF) = 12 t / hour). In the purification column B, the diphenyl carbonate extracted from the side cut outlet B2 had a high boiling point component (hereinafter also referred to as "HB") concentration of 7 mass ppm and an altered substance (XA) concentration of 10 mass ppm. The purity of the diphenyl carbonate obtained from the side cut outlet B2 of the diphenyl carbonate purification column B was 99.99% or more. The operation conditions of the purification column A were a reflux ratio of 3.49, a column top reflux amount of 23,700 kg / hour, and a column bottom temperature of 206° C. The steam consumption in the reboiler of the purification column A was 5,300 kg / hour. The operation conditions of the purification column B were a reflux ratio of 1.87, a column top reflux amount of 2250 kg / hour, and a column bottom temperature of 211° C. The steam consumption in the reboiler of the purification column B was 3600 kg / hour. The operating results of Example 1 are shown in Table 1.

[0179] <Examples 2 to 7> Diphenyl carbonate was produced in the same manner as in Example 1, except that the conditions of purification columns A and B were changed as shown in Table 1. The operating results of each example are shown in Table 1.

[0180] <Comparative Example 1> FIG. 2 is a schematic process flow diagram of the purification method of diphenyl carbonate used in Comparative Example 1. As shown in FIG. 2, a continuous multi-stage distillation column without a side cut outlet was used as the purification column A, and diphenyl carbonate was produced in the same manner as in Example 1, except that the conditions of purification columns A and B were changed as shown in Table 1. Table 1 shows the operating results of Comparative Example 1. As shown in Table 1, in Comparative Example 1, the ratio of the column bottom withdrawal amount to the feed amount in purification column A (column bottom withdrawal amount / feed amount) was high, and the amount of loss in purification was high compared to the Examples. In addition, in Comparative Example 1, the amount of steam used in the reboilers of purification columns A and B relative to the production amount was high, and the energy consumption in purification was high compared to the Examples. In particular, in Comparative Example 1, the amount of steam used in the reboiler of purification column B relative to the production amount was extremely high, and the energy consumption in purification column B was significantly higher than in the Examples.

[0181] The conditions and results of Examples 1 to 7 and Comparative Example 1 are shown in Table 1. [Table 1]

[0182] This application is based on a Japanese patent application (Patent Application No. 2021-163793) filed on October 5, 2021, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0183] By carrying out the method of the present invention, for example, high purity diaryl carbonate necessary for producing high quality and high performance aromatic polycarbonate can be produced on an industrial scale at 0.5 tons or more, preferably 1 ton or more, more preferably 2 tons or more, and even more preferably 3 tons or more per hour with little loss and with reduced energy consumption. Therefore, the present invention is an extremely effective method for industrially producing high purity diaryl carbonate. [Explanation of symbols]

[0184] (Figs. 1 and 2) A1: Crude ethylene carbonate inlet A2: Side cut outlet of purification tower A B1: Inlet of purification tower B B2: Side cut outlet of purification tower B 13, 23: Top gas outlet 18, 28: Heat exchanger (reboiler) 14, 24: Heat exchanger (condenser) 16, 26: Top component withdrawal outlet 17, 27: bottom liquid outlet 11, 12, 31: bottom component outlet 15, 25: Reflux liquid inlet D A : Diameter of purification tower A D B , D B1 , D B2 : Diameter of purification tower B (Figure 3) 1: Gas outlet, 2: Liquid outlet, 3-a to 3-e: Inlets, 4-a to 4-b: Inlets, 5: Head plate, 6: Internal, 7: Torso part, 10: Continuous multi-stage distillation column, L0: Body length (cm), D0: inner diameter of the body (cm), d 01 : Inner diameter of gas outlet (cm), d 02 : Inner diameter of liquid outlet (cm) (Figs. 4, 5 and 6) 1: Gas outlet, 2: Liquid outlet, 3: Inlet, 4: Inlet, 5: Head plate, L1 and L2: trunk length (cm), D1 and D1: inner diameter of the body (cm), d 11 and d 21 : inner diameter of gas outlet (cm), d 12 and d 22 : inner diameter of liquid outlet (cm), 101: first continuous multi-stage distillation column; 201: second continuous multi-stage distillation column, 11, 12, 21: Entrance, 13, 23: column top gas outlet, 14, 24, 18, 28: heat exchanger, 17, 27: column bottom liquid withdrawal port, 16, 26: column top component withdrawal port, 31: second continuous multi-stage distillation column bottom component withdrawal port

Claims

1. A method for continuously producing high purity diaryl carbonate, comprising the steps of: a first purification step in which a mixture containing a diaryl carbonate is continuously introduced into a purification column A having a side cut withdrawal port, and the mixture is continuously separated by distillation into a column top component (At), a side cut component (As) containing the diaryl carbonate, and a column bottom component (Ab) containing the catalyst; a second purification step in which the side cut component (As) is continuously introduced into a diaryl carbonate purification column B having a side cut withdrawal port and continuously separated by distillation into three components, i.e., a column top component (Bt), a side cut component (Bs) and a column bottom component (Bb), to obtain a high-purity diaryl carbonate as the side cut component (Bs); Including, An industrial method for producing high-purity diaryl carbonate, in which the ratio (SA / BsF) of the column cross-sectional area (SA (m2)) of purification column A to the production amount (BsF (tons / hour)) extracted as a side cut component (Bs) is in the range of 0.5 or more and 5 or less.

2. The method according to claim 1 , wherein the mixture contains the diaryl carbonate in an amount of 40% by mass or more and 90% by mass or less.

3. The method according to claim 1 , wherein the mixture contains 10% by mass or more and 50% by mass or less of alkyl aryl carbonate.

4. The production method according to claim 1, wherein the content of the diaryl carbonate in the side cut component (As) is 80% by mass or more, and the content of the diaryl carbonate in the side cut component (Bs) is 99.1% by mass or more.

5. The method according to any one of claims 1 to 3, wherein the number of theoretical plates An from the bottom of the purification column A to the side cut outlet is in the range of 10 to 19.

6. The method according to claim 1, wherein the ratio (DB1 / DB2) of the upper column diameter (DB1 (m)) to the lower column diameter (DB2 (m)) in the purification column B is in the range of 0.1 to 0.

9.

7. The method according to claim 4, wherein the ratio (DB1 / DB2) of the upper column diameter (DB1 (m)) to the lower column diameter (DB2 (m)) in the purification column B is in the range of 0.1 to 0.

9.

8. The process according to claim 1, wherein the purification column A comprises at least one reboiler selected from the group consisting of a forced circulation type, a cross-pipe falling film type, and a thin film evaporation type.

9. The method according to claim 1 , wherein the packing of the purification column A and / or the purification column B is structured packing.

10. The method according to claim 1, wherein the mixture is a reaction mixture obtained by at least one reaction selected from the group consisting of (i) a transesterification reaction between a dialkyl carbonate and an aryl alcohol, (ii) a disproportionation reaction of an alkylaryl carbonate, and (iii) a transesterification reaction between an alkylaryl carbonate and an aryl alcohol in the presence of a catalyst.

11. a step of continuously supplying a dialkyl carbonate and an aryl alcohol into a first continuous multi-stage distillation column in the presence of a catalyst, simultaneously carrying out reaction and distillation in the first continuous multi-stage distillation column, continuously withdrawing a first column low-boiling point reaction mixture containing the produced alcohols in a gaseous state from an upper portion of the first continuous multi-stage distillation column, and continuously withdrawing a first column high-boiling point reaction mixture containing the produced alkyl aryl carbonate in a liquid state from a lower portion of the first continuous multi-stage distillation column, thereby continuously producing an alkyl aryl carbonate; continuously supplying the first column high-boiling point reaction mixture into a second continuous multi-stage distillation column in the presence of a catalyst, and simultaneously carrying out reaction and distillation in the second continuous multi-stage distillation column, continuously withdrawing the second column low-boiling point reaction mixture containing the produced dialkyl carbonates in a gaseous state from an upper portion of the second continuous multi-stage distillation column, and continuously withdrawing the second column high-boiling point reaction mixture containing the produced diaryl carbonate in a liquid state from a lower portion of the second continuous multi-stage distillation column, thereby continuously producing diaryl carbonate, 2. The process according to claim 1, wherein the mixture containing diaryl carbonate is a second column higher boiling reaction mixture containing diaryl carbonate.

12. The process according to claim 1 , wherein the diaryl carbonate is diphenyl carbonate.

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