WO2006033291A1

WO2006033291A1 - Industrial separator for by-product alcohols

Info

Publication number: WO2006033291A1
Application number: PCT/JP2005/017117
Authority: WO
Inventors: Shinsuke Fukuoka; Hironori Miyaji; Hiroshi Hachiya; Kazuhiko Matsuzaki
Original assignee: Asahi Kasei Chemicals Corporation
Priority date: 2004-09-21
Filing date: 2005-09-16
Publication date: 2006-03-30
Also published as: JP2007326782A

Abstract

The invention aims at providing an industrial separator which makes it possible to separate an alcohol efficiently and stably over a long time from a large amount of a low-boiling reaction mixture which is produced in subjecting a dialkyl carbonate and an aromatic monohydroxy compound to trans- esterification in a reactive distillation column in the presence of a catalyst to mass-produce an aromatic carbonate on an industrial scale of 1 ton/hour or above and contains the alcohol as by-product. A continuous multistage distillation column having a specific structure is provided as an industrial separator for by-product alcohols capable of attaining the aim.

Description

Specification

Industrial separation equipment for by-product alcohols

Technical field

[0001] The present invention relates to an industrial separation apparatus for by-product alcohols. More specifically, alcohols by-produced when aromatic carbonates are continuously produced on an industrial scale of 1 ton or more per hour by transesterification of dialkyl carbonate and aromatic monohydroxy compound. The present invention relates to an industrial separation apparatus for separating alcohols.

Background art

[0002] Aromatic carbonate is important as a raw material for producing aromatic polycarbonate, which is the most demanding engineering plastic, without using toxic phosgene. As a method for producing aromatic carbonates, a method based on a reaction between an aromatic monohydroxy compound and phosgene has been known for a long time, and various methods have been studied recently. Aromatic carbonates produced by this method contain chlorine-based impurities that are difficult to separate, and cannot be used as a raw material for aromatic polycarbonate, for example, where high purity is required.

[0003] On the other hand, a method for producing an aromatic carbonate by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound is also known. However, since all these ester exchange reactions are equilibrium reactions, the reaction speed is slow in addition to the fact that the equilibrium is extremely biased toward the original system. It was very difficult to industrially produce large quantities of aromatic carbonates. Therefore, in addition to the development of catalysts, many attempts have been made to improve the yield of aromatic carbonates by shifting the equilibrium to the production system side as much as possible by devising the reaction system. For example, in the reaction of dimethyl carbonate and phenol, methanol produced as a by-product is distilled off together with the azeotropic agent by azeotropic distillation (Patent Document 1: Japanese Patent Laid-Open No. 54-48732 (West German Patent Publication) 736063, U.S. Pat. No. 4,252,737)), a method of removing by-product methanol by adsorbing it with a molecular sieve (Patent Document 2: JP-A-58-185536) U.S. Pat. No. 410464)) has been proposed. Also proposed is a method in which a distillation column is provided at the top of the reactor to separate the alcohols by-produced in the reaction from the reaction mixture while distilling the unreacted raw material from the reaction mixture. (Patent Document 3-1: Examples of JP-A-56-123948 (US Pat. No. 4,182,726)); Patent Documents 3-2; Examples of JP-A-56-25138; Patent Documents 3-3: Examples of JP-A-60-169444 (US Pat. No. 4,554,110); Patent Document 3-4: JP-A-60-169445 (US Pat. No. 4,552,704) Examples; Patent Document 3 5: Example of JP-A-60-173016 (US Pat. No. 4,609,501); Patent Document 3-6: Example of JP-A-61-172852; Patent Document 3 — 7: Examples of JP-A 61-29 1545; Patent Document 3-8: Examples of JP-A 62-277345). The inventors of the present invention continuously supply dialkyl carbonate and aromatic hydroxy compound to a multistage distillation column, continuously react in the column in the presence of a catalyst, and have a low boiling point containing alcohol as a by-product. A reactive distillation method in which components are continuously extracted by distillation and a component containing the generated alkylaryl carbonate is extracted from the lower part of the column (Patent Document 4: Japanese Patent Laid-Open No. 3-291257). Including the diaryl force-bonate that is fed to the distillation column, continuously reacted in the column in the presence of the catalyst, continuously withdrawing low-boiling components including dialkyl carbonate as a by-product by distillation. A reactive distillation method in which components are extracted from the lower part of the column (Patent Document 5: Japanese Patent Laid-Open No. 4 1993-58), these reactions are performed using two continuous multistage distillation columns, and by-products are generated as a by-product Reactive distillation method for continuously producing diaryl carbonate while efficiently recycling kill carbonate (Patent Document 6: Japanese Patent Laid-Open No. 4211038), dialkyl carbonate and aromatic hydroxy compound continuously To the multi-stage distillation column, and the liquid flowing down in the column is withdrawn from the side extraction port provided in the middle stage and Z or the lowest stage of the distillation column, and introduced into the reactor provided outside the distillation column. The reaction distillation method in which the reaction is carried out in both the reactor and the distillation column by introducing it into a circulation inlet provided at a stage higher than the stage having the extraction port after the reaction (patent Document 7-1: JP-A-4-224547; Patent Document 7-2: JP-A-4 230242; Patent Document 7-3: JP-A-4 235951), etc. Reaction and distillation in distillation column We have developed a system that simultaneously performs separation and disclosed for the first time in the world that reactive distillation is useful for these transesterification reactions.

[0005] These reactive distillation methods proposed by the present inventors are the first to make it possible to produce aromatic carbonates efficiently and continuously, and are based on these disclosures thereafter. Many similar reactive distillation systems have been proposed (Patent Document 8: Italian Patent No. 01255746; Patent Document 9: JP-A-6-9506 (European Patent No. 056 0159, US Patent No. Patent Document 10: Japanese Patent Laid-Open No. 6-41022 (European Patent 0572870, US Patent No. 5362901); Patent Document 11: Japanese Patent Laid-Open No. 6-157424 (European Patent) No. 0582931, U.S. Pat. No. 533 4742); Patent Document 12: JP-A-6-184058 (European Patent 0582930, US Pat. No. 5344954); Patent Document 13: JP-A-7 — Publication No. 304713; Patent Document 14: Japanese Patent Laid-Open No. 9-40616; Patent Document 15 : JP-A-9-59225; Patent Document 16: JP-A-9-110805; Patent Document 17: JP-A-9-165357; Patent Document 18: JP-A-9-173819; Patent Document 19- 1: JP-A-9-176094; Patent Document 19-2: JP-A 2000-191596; Patent Document 19-3: JP-A 2000-191597; Patent Document 20: JP-A-9-194436 (European Patent No. 0785184, US Pat. No. 5,705,673); Patent Document 21: International Publication No. 00Z1872 0 (US Pat. No. 6093842); Patent Document 22-1: Japanese Patent Laid-Open No. 2001-64234 Patent Document 22-2: JP 2001-64235 A; Patent Document 23: International Publication No. 02Z 40439 (US Pat. No. 6,596,894, US Pat. No. 6596895, US Pat. No. 660 0061)).

[0006] On the other hand, some proposals have been made for a method for separating the alcohols from a reaction mixture containing methanols by-produced by transesterification of dimethyl carbonate and phenol. For example, the liquid phase part is divided into a plurality of reaction compartments, and the reaction liquid flows out through each compartment in sequence, and the above reaction is carried out using the reactor. The gas in the gas phase part is extracted using a method of extracting the gas in the phase part, separating the gas in the distillation column after heat exchange (Patent Document 24: JP-A-2003-113144) or the same reactor, After this is heat-exchanged and liquidized, the pressure in the gas phase part of the reactor A high-pressure distillation separation method (Patent Document 25: Japanese Patent Laid-Open No. 2003-155264) has been proposed. However, the purpose of these methods is to separate the gas components when they are reacted using the continuous stirring tank as described above as a reactor in an energy-saving manner. the composition of the gas component, for example, dimethyl carbonate 98.1 weight ^_0/0, methanol 1.4 mass ^_0/0, phenol, Mechirufue - a le carbonate 0.5 wt% (Patent Document 25), a reactive distillation method The composition of the low-boiling point reaction mixture containing by-product alcohols produced by the above is greatly different from the separation of alcohols from the low-boiling point reaction mixture by the reactive distillation method at a predetermined concentration. . A method of distilling a liquid containing about 10 to 74% by mass of methanol at about 30 gZhr from the top of a distillation column installed at the top of a tank reactor (Patent Document 26: JP-A-6-157410) is also proposed. ing. However, these patent documents are of small laboratory scale, or are there! /, Which are just a comparative calculation of the amount of energy required for distillation, both on an industrial scale. There is no specific description or suggestion regarding separation.

[0007] When a transesterification reaction between a dialkyl carbonate and an aromatic hydroxy compound is carried out by a reaction distillation method, the alcohol produced as a by-product usually has a lower boiling point than the aromatic force-bonate present in the reaction system. These compounds are continuously extracted from the upper column of the reactive distillation column as a low-boiling reaction mixture containing, for example, raw material dialkyl carbonate and aromatic hydroxy compound, by-product alkylaryl ether and the like. Since this transesterification reaction is an equilibrium reaction with a very small equilibrium constant, by-product alcohols inhibit this reaction, so the low-boiling-point reaction mixture contains a low alcohol content component and alcohols. For industrial implementation, it is important to separate and recover from the main components efficiently and stably for a long period of time.

[0008] There are several methods for separating low boiling point reaction mixtures containing methanol and dimethyl carbonate extracted by distillation by transesterification of dimethyl carbonate and phenol by reactive distillation. Proposals have been made. They are extracted and distilled by extracting methanol from the top of the column while extracting dimethyl carbonate using dimethyl oxalate as an extractant (Patent Document 27: JP-A-7-101908), and using dimethyl carbonate as an extractant. Tower top while extracting carbonate Extractive distillation method for extracting methanol from the reactor (Patent Document 14), distillation at atmospheric pressure to obtain a mixture consisting of about 70% by mass of methanol and about 30% by mass of dimethyl carbonate (Patent Document 19), To obtain a mixture consisting of 64.5% by mass of methanol and 35.5% by mass of dimethyl carbonate (Patent Document 20), and a mixture of 60 to 40% by mass of methanol and 40 to 60% by mass of dimethyl carbonate. This is a method (Patent Document 15).

However, in the extractive distillation method, a large amount of extractant must be used, and after the extraction, it is necessary to further separate these extractant and dimethyl carbonate. The methanol content in the top extraction liquid is as low as less than 80% by mass, which is not preferred when used as a raw material for producing dimethyl carbonate. Also, these patent documents describe a method for separating and recovering methanol of several lOOgZhr or less, and even in Patent Document 20 describing the maximum amount, the amount of methanol being treated is about 0. 9kgZhr. Furthermore, the continuous time during which methanol is distilled and separated in these patent documents is not the reactive distillation method !, but the reaction method is used! In Patent Document 29, the longest time is 720 hours at most. is there. When the reactive distillation method is used, the maximum force is 2 weeks (Patent Document 19), and the others are 10 days (Patent Document 15) and the time until steady state (Patent Documents 14 and 27). It is very short, and does not give any disclosure or suggestion of an industrial separation method that performs distillation operations stably for a long period of several thousand hours, for example, 5,000 hours. In this way, when aromatic carbonates are produced industrially by reactive distillation, specific methods and equipment relating to industrial methods for efficiently and stably separating large amounts of by-produced alcohols over a long period of time. No specific disclosure or suggestion has been made so far.

Disclosure of the invention

Problems to be solved by the invention

[0010] The problem to be solved by the present invention is that when an aromatic carbonate is continuously produced on an industrial scale of 1 ton or more per hour by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound. Another object of the present invention is to provide an industrial separation apparatus for separating alcohols from a low boiling point reaction mixture containing alcohols as a by-product. Means for solving the problem [0011] As a result of repeated studies to solve the above-mentioned problems and to find out a specific industrial separation apparatus capable of efficiently and stably separating a large amount of by-product alcohols for a long time, the present invention has been achieved. did.

That is, in the present invention,

1. Alcohols produced as a by-product in the continuous production of aromatic carbonates on an industrial scale of 1 ton or more per hour by transesterification of dialkyl carbonates with aromatic monohydroxy compounds. A low boiling point reaction mixture containing alcohol with a length L (cm), an inner diameter D (cm), and an internal number of stages n that satisfy the following formulas (1) to (8): Recovery part with internal, length L (cm), inner diameter D (cm), inside

1 2 It must be a continuous multi-stage distillation column with an enrichment capacity with an internal number n of 2 stages.

2

Industrial separation equipment for by-product alcohols characterized;

500 <L ≤ 3000 (1)

1 set

100 <D ≤ 500 (2)

1

2 <L / Ό ≤ 30 (3)

1 1

10 <n ≤ 40 (4)

1

700 <L ≤ 5000 (5)

2

50 <D ≤ 400 (6)

2

10 <L / Ό ≤ 50 (7)

twenty two

35 <n ≤ 100 (8),

2.L, D, L ZD, n, L, D, L ZD, n of the continuous multistage distillation column are 80

1 1 1 1 1 2 2 2 2 2

0≤L ≤2500, 120≤D ≤400, 5≤L / Ό ≤20, 13≤n≤25, 1500≤ L ≤3500, 70≤D ≤200, 15≤L / Ό ≤30, 40≤n≤ 70, L ≤ L,

2 2 2 2 2 1 2

D ≤ D,

twenty one

An industrial separation apparatus for by-product alcohols according to item 1, characterized in that:

3. Industrial separation of by-product alcohols according to 1 or 2 above, characterized in that the internals of the recovery section and concentration section of the continuous multistage distillation column are tray and Z or packing, respectively. Equipment,

4. The internal parts of the recovery section and concentration section of the continuous multistage distillation column are trays. An industrial separation apparatus for by-product alcohols as described in item 3 above,

5. The industrial separation apparatus for by-product alcohols according to item 4, wherein the tray is a perforated plate tray having a perforated plate portion and a downcomer portion,

6. The industrial separator for by-product alcohols according to 5 above, wherein the perforated plate tray has 100 to LOOO holes per area lm ² of the perforated plate portion,

7. The industrial separation apparatus for by-product alcohols according to item 5 or 6 above, wherein the cross-sectional area per hole of the perforated plate tray is 0.5 to 5 cm ² ,

8. The soot-exchange reaction is carried out by a reactive distillation method, and the low boiling point reaction mixture is mixed with a top component having a concentration of the alcohols of 90% by mass or more and an alcohol content of 0.2% by mass or less. The amount of alcohols separated into a tower bottom component and separated as the tower top component is 200 kg or more per hour, according to any one of the preceding items 1 to 7, Industrial separation equipment for by-product alcohols,

9. Industrial separation of by-product alcohols according to item 8 above, wherein the concentration of the alcohols in the column top component is 95% by mass or more with respect to 100% by mass of the column top component Equipment,

10. The industrial concentration of by-product alcohols according to item 8 above, wherein the concentration of the alcohols in the column top component is 97% by mass or more with respect to 100% by mass of the column top component. Separation device,

11. The content of the alcohol in the column bottom component is 0.1% by mass or less with respect to 100% by mass of the column bottom component, any one of the items 8 to 10 above Industrial separation apparatus for by-product alcohols as described in

I will provide a.

The invention's effect

The industrial separation apparatus according to the present invention is used in the case of continuously producing aromatic carbonates on an industrial scale of 1 ton or more per hour by transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound. The alcohols can be stably and efficiently separated for a long time from the low boiling point reaction mixture containing the resulting alcohols. And the amount of alcohol separated as the top component is more than 200kg per hour, It can be easily separated into a column top component having an alcohol content of 90% by mass or more and a column bottom component having an alcohol content of 0.2% by mass or less.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be specifically described.

The dialkyl carbonate used in the present invention is represented by the general formula (9).

R'OCOOR ¹ (9)

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. For example, 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), alkyl group such as cyclohexylmethyl; cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclo Alicyclic groups such as heptyl; aralkyl groups such as benzyl, phenethyl (each isomer), phenylpropyl (each isomer), vinyl butyl (each isomer), methylbenzyl (each isomer) . These alkyl groups, alicyclic groups, and aralkyl groups may be substituted with other substituents such as a lower alkyl group, lower alkoxy group, cyan group, halogen, etc., or unsaturated. Have a bond.

[0015] Examples of such dialkyl carbonate having R ¹ include dimethyl carbonate, jetyl carbonate, dipropyl carbonate (each isomer), diaryl carbonate, dibutenyl carbonate (each isomer), and 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, dicyclohexenole carbonate, dicycloheptinole carbonate, dibenzino carbonate, diphenethyl carbonate (each isomer), Di (phenol) carbonate (each isomer), di (fluoro) - Rubuchiru) carbonate (isomers), di (black port benzyl) carbonate sulfonate (isomers), di (methoxybenzyl) carbonate (isomers), di (methoxymethyl ) Carbonate, di (methoxyethyl) carbonate (each isomer), di (chloroethyl) carbonate (each isomer), di (cyanoethyl) carbonate (each isomer), and the like.

[0016] Among these, R ¹ is preferably a dialkyl carbonate composed of an alkyl group having 4 or less carbon atoms not containing a halogen, particularly preferably! / Is dimethyl carbonate, which is preferably used in the present invention. . Further, among the preferred dialkyl carbonates, more preferred are dialkyl carbonates produced in a state substantially free of halogen! /, For example, alkylene carbonates substantially free of halogen. Alcohol power substantially free of halogen and halogen is also produced.

[0017] The aromatic monohydroxy compound used in the present invention is represented by the following general formula (10), and if the hydroxyl group is directly bonded to the aromatic group, It can be anything.

Ar'OH (10)

Here, Ar ¹ represents an aromatic group having 5 to 30 carbon atoms. Examples of such aromatic monohydroxy compounds having Ar ¹ include phenol; talesol (each isomer), xylenol (each isomer), trimethylphenol (each isomer), tetramethylphenol (each isomer), Ethylphenol (each isomer), Propylphenol (each isomer), Butylphenol (each isomer), Jetylphenol (each isomer), Methylethylphenol (each isomer), Methylpropylphenol (each Isomers), dipropylphenol (each isomer), methylbutylphenol (each isomer), pentylphenol (each isomer), hexylphenol (each isomer), cyclohexylphenol (each isomer), etc. Various alkylphenols; various alcohols such as methoxyphenol (each isomer) and ethoxyphenol (each isomer) Phenols; arylalkylphenols such as phenolpropylphenol (each isomer); naphthol (each isomer) and various substituted naphthols; hydroxypyridine (each isomer), hydroxycoumarin (each isomer), Heteroaromatic monohydroxy compounds such as hydroxyquinoline (each isomer) are used. Among these aromatic monohydroxy compounds, those that are preferably used in the present invention are aromatic monohydroxy compounds in which Ar ¹ also has an aromatic group having 6 to 10 carbon atoms. Preference is given to phenol. Among these aromatic monohydroxy compounds, those preferably used in the present invention are It is substantially free of rogen.

[0018] In the transesterification reaction of the present invention, the reaction for producing an aromatic carbonate and by-producing alcohols is represented by the following formulas (11, 12). In the present invention, the reaction formula (11) The reaction is mainly occurring.

R'OCOOR ¹ + Ar'OH → Ar'OCOOR ¹ + R'OH (11)

Ar ^ COOR ^ Ar'OH → Ar'OCOOAr ¹ + Ι ^ ΟΗ (12)

[0019] The molar ratio of the dialkyl carbonate and the aromatic monohydroxy compound used in the transesterification reaction of the present invention is required to be 0.5 to 3 in terms of molar ratio. Outside this range, the remaining unreacted raw material increases with respect to the predetermined production amount of the target aromatic carbonate, which is not efficient and requires a lot of energy to recover them. In this sense, this mono ktti is more preferably 0.8 to 2.5 force, and more preferably ί ί, 1.0 to 2.0.

[0020] The transesterification reaction of the present invention is a method capable of continuously producing an aromatic carbonate at a production rate of 1 ton or more per hour and producing a low boiling point reaction mixture containing by-produced alcohols. Any method can be used, but the reaction distillation method is particularly preferred. The aromatic carbonate produced in the present invention is an alkyl aryl carbonate, diaryl carbonate, or a mixture thereof obtained by transesterification of a dialkyl carbonate and an aromatic monohydroxy compound. In this ester exchange reaction, one or two alkoxy groups of the dialkyl carbonate were exchanged with the aryloxy group of the aromatic monohydroxy compound to remove alcohols (formulas 11 and 12). Alkylaryl carbonate A reaction that converts to diaryl carbonate and dialkyl carbonate by a disproportionation reaction (Equation 13), which is an ester exchange reaction between two molecules, may be included.

2Ar ¹ OCOOR ¹ → Ar'OCOOAr ¹ + R'OCOOR ¹ (13)

In the transesterification reaction of the present invention, alkylaryl carbonate is mainly obtained. This alkylaryl carbonate is further subjected to ester exchange reaction with an aromatic monohydroxy compound, or disproportionation reaction (formula 13 ) Can be used to make a gear reel carbonate. This diaryl carbonate was completely free of halogen. Therefore, it is important as a raw material when industrially producing polycarbonate by the transesterification method. In the transesterification reaction of the present invention, a small amount of alkyl aryl ether is usually produced as a reaction byproduct.

[0022] The dialkyl carbonate and aromatic monohydroxy compound used as raw materials in the transesterification reaction of the present invention may have high purity, but may contain other compounds. . For example, it may contain compounds and reaction byproducts produced in this step and z or other steps. When industrially used, these raw materials include dialkyl carbonates and aromatic monohydroxy compounds that are newly introduced into the reaction system, as well as those recovered from this step and Z or other steps. And are preferred. By using the industrial separation apparatus of the present invention, the low boiling point reaction mixture withdrawn from the upper part of the reactor is continuously distilled and separated, so that the component having a low alcohol content is used as a raw material for the transesterification reaction. It can be reused, and this is a particularly preferred method.

[0023] The transesterification reaction of the present invention is usually carried out in the presence of a known catalyst. For example, when the transesterification reaction is carried out by a reactive distillation method, these catalysts may be solid catalysts fixed in a multistage distillation column that performs reactive distillation, or may be soluble catalysts that are dissolved in the reaction system. May be. Of course, these catalyst components reacted with organic compounds present in the reaction system, such as aliphatic alcohols, aromatic monohydroxy compounds, alkyl aryl carbonates, diaryl carbonates, dialkyl carbonates and the like. It may be a product, or it may have been heat-treated with raw materials and products prior to the reaction! When the transesterification reaction of the present invention is carried out with a soluble catalyst that dissolves in the reaction system, it is preferable that these catalysts have high solubility in the reaction solution under the reaction conditions. Preferred catalysts in this sense include, for example, PbO, Pb (OH), Pb (0

2

Ph); TiCl, Ti (OMe), (MeO) Ti (OPh), (MeO) Ti (OPh), (MeO) Ti (0

2 4 4 3 2 2 3

Ph), Ti (OPh); SnCl, Sn (OPh): Bu SnO, Bu Sn (OPh); FeCl, Fe (OH)

4 4 4 2 2 2 3 3

, Fe (OPh), etc., or those treated with phenol or reaction liquid, etc.

Three

It is done.

[0024] In the present invention, when the transesterification reaction is performed by a reactive distillation method, the continuous multi-stage steaming is performed. Any method may be used in which the catalyst is present in the distillation column (hereinafter referred to as “continuous multistage distillation column A”). However, when the catalyst is in a solid state insoluble in the reaction solution, Multi-stage distillation column There are methods such as installing in the column in column A, or fixing it in the column by installing it in a packed form. Further, in the case of a catalyst that dissolves in the raw material or the reaction solution, it is preferable to supply it into the upper force distillation column from the middle part of the distillation column A. In this case, the catalyst solution dissolved in the raw material or the reaction solution may be introduced together with the raw material, or the catalyst solution may be introduced from an inlet different from the raw material. The amount of catalyst used in the present invention is usually expressed as a ratio with respect to the total weight of the raw material, which varies depending on the type of catalyst used, the type of raw material and its ratio, reaction temperature and reaction pressure, and other reaction conditions 0.0001 to 30% by mass, preferably 0.005 to 10% by mass, more preferably 0.001 to 1% by mass.

FIG. 1 is a schematic diagram showing an example of a continuous multi-stage distillation column A that performs reactive distillation, which is a preferred reaction method for performing a transesterification reaction of the present invention. In the present invention, when the transesterification reaction is carried out by the reactive distillation method, the continuous multistage distillation column A used as the reactive distillation column is long in the production amount of 1 ton or more of at least one aromatic carbonate per hour. Any material can be used as long as it can be stably produced over a period of time. For example, a length L (cm) that satisfies the conditions of the following formulas (14) to (19) and an inner diameter D (cm ), And has an internal structure (for example, tray 6) with an internal stage number n, and a gas outlet 1 with an inner diameter d (cm) at the top of the tower or near the top of the tower, a tower at or near the bottom of the tower. Inside diameter d (cm)

1 2 liquid outlet 2, one or more inlets below the gas outlet and above the tower and in the Z or middle part 3, one or more above the liquid outlet and below the tower Especially preferred is a continuous multi-stage distillation column A having 4 inlets.

As used herein, the term “top of the tower or near the top of the tower” means a portion of about 0.25 L downward from the top of the tower, and the term “bottom of the tower or near the bottom of the tower” It means the part up to about 0.25L from the bottom of the tower. “L” is as defined above.

1500 ≤ L ≤ 8000 formula (14)

100 ≤ D ≤ 2000 formula (15)

2 ≤ L / D ≤ 40 Equation (16) 20 ≤ n ≤ 120 Equation (17)

5 ≤ D / d ≤ 30 formula (18)

3 ≤ D / d ≤ 20 Equation (19)

2

By using continuous multistage distillation column A that simultaneously satisfies the formulas (14) to (19) as a reactive distillation column, 1 ton or more per hour from a dialkyl carbonate and an aromatic monohydroxy compound, usually 1 to : On the industrial scale of LOO Tong Zhr, aromatic carbonates have high selectivity and high productivity. For example, 2000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more Can be manufactured.

[0026] The transesterification reaction carried out in the present invention is carried out continuously, and the reaction time is considered to correspond to the average residence time of the reaction liquid in the reactor. It varies depending on the amount supplied, the type and amount of the catalyst, the reaction conditions, etc. In the case of the reactive distillation method, it varies depending on the internal shape of the distillation column, the number of stages, the distillation conditions, etc. 0.05 to 5 hours, more preferably 0.1 to 3 hours. The reaction temperature varies depending on the type of raw material compound used and the type and amount of the catalyst, but is usually 100 to 350 ° C. In order to increase the reaction rate, it is preferable to increase the reaction temperature. If the reaction temperature is high, side reactions are liable to occur. For example, by-products such as alkyl aryl ether increase, which is not preferable. In this sense, a preferable reaction temperature is 130 to 280. C, more preferably 150-260. C, more preferably 180-250. C range. The reaction pressure varies depending on the type and composition of the raw materials used, the reaction temperature, etc. 1S reduced pressure, normal pressure, or pressurized pressure is usually 0.1-2 X 10 ⁷ Pa, preferably Is carried out in the range of 10 ⁵ to: L0 ⁷ Pa, more preferably 2 × 10 ^{5 to} 5 × 10 ⁶ .

[0027] When the transesterification reaction of the present invention is carried out, a low-boiling point reaction containing alcohols produced by continuously supplying a raw material dialkyl carbonate and an aromatic monohydroxy compound to a reactor in which a catalyst exists. Aromatic carbonates are continuously produced by continuously withdrawing the mixture in gaseous form from the upper part of the reactor and continuously withdrawing the high boiling point reaction mixture containing the aromatic carbonates in liquid form from the lower part of the tower. . In the case of the present invention, a reactive distillation system in which the reactor is a continuous multistage distillation column A is preferred. In this case, the raw material is continuously fed into the continuous multistage distillation column A in which a catalyst is present, Simultaneous reaction and distillation The low boiling point reaction mixture (hereinafter referred to as “A”) containing the generated alcohols is

T

The aromatic carbonate is continuously withdrawn in a gaseous state, and a high boiling point reaction mixture containing aromatic carbonates (hereinafter referred to as “A”) is continuously withdrawn in liquid form from the bottom of the column.

B

Are produced continuously.

[0028] When producing aromatic carbonates at 1 ton Zhr or more, alcohols are usually by-produced by about 200 kgZhr or more. These by-product alcohols are present in the reaction system from the upper part of the reactor as a low-boiling point reaction mixture (A) together with compounds having a lower boiling point than aromatic carbonates, such as unreacted raw materials and by-product alkylaryl ethers. Continuously

T

Is issued. Of course, in the low boiling point reaction mixture (A), aromatic carbonate and

T

It may contain a small amount of high boiling point compounds. In the present invention, the amount of the low boiling point reaction mixture (A) continuously withdrawn from the reactor depends on the raw material composition and amount, the reactive distillation conditions, and the reaction.

T

The force varies depending on the response rate, selectivity, etc. Usually, it is 10 tons Zhr or more and 1000 tons Zhr or less.

[0029] In the present invention, the composition of the low boiling point reaction mixture (A) to be separated has reaction conditions! /,

T

Varies depending on the reaction distillation conditions of the continuous multistage distillation column A, the raw material composition to be recycled, etc. The low boiling point reaction mixture (A) is usually used as a by-product alcohol 1.5 to 100% by mass.

T

10 mass ^_0/0, dialkyl carbonate 50-85 mass ^_0/0, the aromatic monohydroxy compound 10 40 mass%, alkyl § reel ether 0.5 to 10 wt% by-products, aromatic force Boneto 0-5 % By weight, others 0-3% by weight.

FIG. 2 is a schematic diagram showing an example of a continuous multistage distillation column (hereinafter referred to as “continuous multistage distillation column B”) which is an industrial separation apparatus for by-product alcohols of the present invention. The present invention provides a separation apparatus suitable for efficiently distilling and separating the low boiling point reaction mixture having such a composition containing by-product alcohol on an industrial scale, and the separation apparatus comprises: A recovery section SS having an internal length (for example, tray 7) having a length L (cm), an inner diameter D (cm), and an internal number n (for example, tray 7) satisfying the formulas (1) to (8), and a length L (cm), inner diameter D (cm), and n steps inside

2 2 A distillation column consisting of a concentrating section ES with two internals (eg, tray 8) is required. Reference numerals 1 to 4 in FIG. 2 denote the same members as in FIG.

500 ≤ L ≤ 3000 Formula (1) 100 D ≤ 500 (2)

1

2 L / D ≤ 30 (3)

1 1

10 n ≤ 40 (4)

1

700 L ≤ 5000 (5)

2

50 D ≤ 400 (6)

2

10 L / D ≤ 50 (7)

twenty two

35 n ≤ 100 (8)

By using such a continuous multi-stage distillation column B, it has become clear that the above object can be easily achieved. Although this separation device is an industrial separation device for by-product alcohols, the reason for this excellent effect is not clear, but because of the combined effect brought about when the conditions of formulas (1) to (8) are combined. Presumed to be

[0031] The preferred range of each factor is shown below. If the L (cm) force is less than 00, the separation efficiency of the recovery unit will decrease, and the target separation efficiency will not be achieved.To reduce the equipment cost while ensuring the target separation efficiency, L should be It is necessary to make it smaller. A more preferable range of L (cm) is 800≤L≤2500, and more preferably 1 000≤L≤2000.

[0032] If D (cm) is smaller than 100, the target distillation amount cannot be achieved, and D must be smaller than 500 in order to reduce the equipment cost while achieving the target distillation amount. is there. A more preferable range of D (cm) is 120≤D ≤400, and more preferably 150≤D ≤300.

[0033] When it is less than L ZD or greater than 30, long-term stable operation becomes difficult. A more preferred range of L / Ό is 5≤L ZD ≤20, more preferably 7≤L / Ό ≤15.

[0034] If n is less than 10, the separation efficiency of the recovery unit is lowered, so that the target separation efficiency cannot be achieved. To reduce the equipment cost while ensuring the target separation efficiency, n is less than 40. It is necessary to drill. A more preferable range of n is 13≤n≤25, and more preferably 15≤n≤20. [0035] If L (cm) is less than 700, the separation efficiency of the concentrating part is lowered, so that the desired separation effect is achieved.

2

To reduce the equipment cost while ensuring the desired separation efficiency,

2

It is necessary to make it smaller than 000. Pressure above and below the tower when L is greater than 5000

2

Because the difference becomes too large, long-term stable operation becomes difficult, and the temperature at the bottom of the tower must be increased, so side reactions are likely to occur. More preferable range of L (cm)

2 The range is 1500≤L≤3500, more preferably 2000≤L≤3000.

twenty two

[0036] If D (cm) is less than 50, the target distillation amount cannot be achieved, and the target distillation amount cannot be achieved.

2

In order to reduce equipment costs while achieving this, it is necessary to make D smaller than 400. Than

2

The preferred range of D (cm) is 70≤D ≤200, more preferably 80≤D ≤15

2 2 2

0.

[0037] When L / Ό is less than 10 or greater than 50, long-term stable operation becomes difficult. More preferred

twenty two

The range of new L / 15 is 15≤L ZD ≤30, more preferably 20≤L / Ό ≤

2 2 2 2 2 2

28.

[0038] If n is less than 35, the separation efficiency of the concentrating part decreases, and the target separation efficiency is achieved.

2

In order to reduce the equipment cost while ensuring the desired separation efficiency, n is less than 100.

2

It is necessary to make it smaller. If n is greater than 100, the pressure difference between the top and bottom of the tower is large.

2

As the temperature becomes too high, long-term stable operation becomes difficult, and the temperature at the bottom of the tower must be increased, which leads to side reactions. The more preferable range of n is 40≤n

twenty two

≤70, and more preferably 45≤n≤65.

2

[0039] Also, in the continuous multistage distillation column A, L, D, LZD, n, D / d, D / d force respectively.

1 2

2000≤L≤ 6000, 150≤D≤1000, 3≤L / D≤30, 30≤n≤100, 8 ≤D / d ≤25, 5≤D / d ≤ 18, preferably Preferably 2500≤L

1 2

≤5000, 200≤D≤800, 5≤L / D≤15, 40≤n≤90, 10≤D / d ≤25, 7≤D / d ≤15. Also, the relationship with L and the relationship between D and D are separated

2 1 2 1 2

It depends on the amount of the low boiling point reaction mixture (A) to be obtained and the concentration of alcohols.

T

However, it is usually preferable that L ≤ L and D ≤ D.

1 2 2 1

[0040] The continuous multistage distillation column B used for industrial separation of by-product alcohols of the present invention is a distillation having a tray and Z or a packing as an internal in a recovery part SS and a concentrating part ES. A tower is preferred. The term “internal” as used in the present invention means a portion where gas-liquid contact is actually performed in a distillation column. As such a tray, for example, a foam tray, a perforated plate tray, a valve tray, a counterflow tray, a super flack tray, a max flutter tray, etc. Irregular packing such as Nolenore Sad Nore, Interlocks Saddle, Dixon Packing, McMahon Packing, Helical Pack, etc. I like it. A multistage distillation column having both a tray part and a packed part can also be used. The term “internal plate number n” used in the present invention means the number of trays in the case of trays, and the theoretical plate number in the case of packing. Therefore, in the case of a continuous multistage distillation column having both a tray part and a packed part, n is the sum of the number of trays and the number of theoretical plates.

In the present invention, it is particularly preferable that the internals of the recovery section SS and the concentration section ES of the continuous multistage distillation column B are trays. It was also found that a perforated plate tray having a perforated plate portion and a downcomer portion is particularly excellent in terms of function and equipment costs. It has also been found that it is preferred that the perforated plate tray has 100-: LOOO holes per area lm ² of the perforated plate portion! More preferably! / The number of fistulas is 120-900 per lm ^{2 of the} area, and more preferably 150-800. It has also been found that the cross-sectional area per hole of the perforated plate lay is preferably 0.5 to ⁵ cm ² . The cross-sectional area per hole is more preferably 0.7 to ⁴ cm ² , and further preferably 0.9 to ³ cm ² . Further, when the perforated plate tray has 100 to: LOOO holes per area lm ² of the perforated plate portion, and the cross-sectional area per hole is 0.5 to ⁵ cm ² , It has been found to be particularly preferred. By adding the above conditions to the continuous multistage distillation column B, it has been found that the object of the present invention can be achieved more easily. Furthermore, when the ester exchange reaction of the present invention is carried out by the reactive distillation method, it is preferable to use the above-mentioned internal also for the continuous multistage distillation column A used as the reactive distillation column, and particularly the formulas (11) and (12). It is preferable to use a tray for a reactive distillation column that mainly performs the reaction of (3) and an internal tray and a regular packing for a reactive distillation column that mainly performs the reaction of the formula (13). [0042] When continuous separation is performed using the separation apparatus of the present invention, a low boiling point reaction mixture of a transesterification reaction containing by-product alcohols may be supplied in a gaseous state into the continuous multistage distillation column B. Although it may be supplied in liquid form, the heat of the low boiling point reaction mixture usually extracted in the form of gas can be used for heating other substances, for example, the raw material of the transesterification supplied to the reactor. This is a particularly preferable method. In this case, depending on the degree of heat exchange, the low boiling point reaction mixture supplied to the continuous multistage distillation column B becomes gaseous, gas-liquid mixed, or liquid. Further, the position where the low boiling point reaction mixture is fed into the continuous multistage distillation column B is between the recovery unit SS and the concentrating unit ES. The continuous multistage distillation column B preferably has a reboiler for heating the distillate and a reflux device.

[0043] In the present invention, a by-product is produced when an aromatic carbonate is continuously produced on an industrial scale of 1 ton Zhr or more by a transesterification reaction between a dialkyl carbonate as a raw material and an aromatic monohydroxy compound. The low-boiling point reaction mixture containing alcohols is usually provided with an industrial distillation apparatus that separates 10 to LO 00 tons Zhr. In this distillation apparatus, the concentration power of the alcohols is 90% by mass or more, preferably Is 95% by mass or more, more preferably 97% or more of the top component (hereinafter referred to as “B”) and the alcohol content is 0.2% by mass.

T

%, Preferably 0.1% by mass or less, more preferably 0.07% by mass or less of the bottom component (hereinafter referred to as “B”) for stable and efficient separation over a long period of time. Is possible. Ma

B

In this separation apparatus, the amount of alcohol separated as the top component (B) is reduced to 200k.

T

gZhr or more, preferably 500 kgZhr or more, more preferably 1 to 20 tons Zhr.

[0044] When the separation operation is carried out in the present invention, the column top component (B) contains 90% by-product alcohols.

T

All or most of the remaining components that are contained in an amount of at least% are usually dialkyl carbonates. Therefore, the tower top component (B) is used as a dialkyl carbonate production raw material.

T

It is preferable to use it. As a method for producing dialkyl carbonate, a method using a carbonylation reaction of alcohols and a method using an alcohololysis reaction of alkylene carbonate are industrially carried out. Any reaction

T

It can also be used as a raw material. Since the alcohololysis reaction of alkylene carbonate is an equilibrium reaction, it is preferable to use a raw material having a high alcohol concentration. It is a preferred method to use the top component (B) as a raw material for this reaction. In this case, the top of the tower

T

The alcohol concentration in component (B) is 95% by mass or more, more preferably 97% by mass or more.

T

Especially preferred to use things as raw materials.

[0045] Further, when the separation operation is carried out in the present invention, the bottom component (B) is mixed with the low boiling point reaction mixture.

B

The component power of the column top component (B) is extracted from the component of the product, and the column bottom component (B) 10

T B

The content of by-product alcohols is 0.2% by mass or less, preferably 0.1% by mass or less with respect to 0% by mass. Usually, the main components are a dialkyl carbonate and an aromatic monohydroxy compound. And a small amount of by-produced alkyl aryl ether and a small amount of aromatic strength bonates. Therefore, this bottom component B is transesterified.

B

It is particularly preferred to recycle and reuse as a raw material.

When performing continuous distillation separation of by-product alcohols using the separation apparatus of the present invention, the distillation conditions of the continuous multistage distillation column B are such that the column bottom temperature is 150 to 300 ° C., preferably 170 to 270 °. C, more preferably 190 to 250 ° C., and the top pressure is 2 × 10 ^{5 to} 5 × 10 ⁶ Pa, preferably 4 × 10 ^{5 to} 3 × 10 ⁶ Pa, more preferably 6 × 10 ⁵ to 2 X 10 ⁶ Pa and the reflux specific force is 0.1 to 20, preferably 0.5 to 15, and more preferably 1.0 to 10.

[0047] The long-term stable operation in the present invention refers to a steady state based on operating conditions where there is no flooding or piping clogging or erosion for 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more. While the operation can be continued and the predetermined separation efficiency is maintained, a predetermined amount of by-product alcohol of 200 kgZhr or more is distilled and separated as the top component (B).

T

Means that

[0048] The material constituting the continuous multistage distillation column, internal, piping, etc. of the present invention is preferably mainly carbon steel, stainless steel or the like.

Example

[0049] The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples. Examples 3 to 7 are examples for showing the performance of the industrial separation apparatus of the present invention. The composition of the mixture was measured by gas chromatography, and the halogen was measured by ion chromatography.

[0050] [Example 1] As shown in Figure 2, Ι ^ = 1700 «η, 180cm, L ^ O ^ = 9.4, 16, L ₂ = 2500 cm, D = 100cm, L / Ό = 25, n = 55, and the internal is Collection unit, concentration unit

2 2 2 2

Both provide a continuous multi-stage distillation column with perforated plate trays (cross-sectional area per hole = about 1.3 cm ² , number of holes = about 550 / m ² ).

[0051] [Example 2]

L = 1200cm, D = 180cm, L / Ό = 4.6, η = 18, L = 2800 cm, D = 160cm, L / Ό = 17.5, n = 58 as shown in Fig. 2, internal Recovery part, concentration

2 2 2 2

A continuous multi-stage distillation column having a perforated plate tray (cross-sectional area per hole = about 1.2 cm ² , number of holes = about 650 / m ² ) is provided.

[0052] [Example 3]

As shown in Figure 1, continuous multistage distillation column A with L = 3300 cm, D = 500 cm, L / D = 6.6, n = 80, D / d = 17 and D / d = 9 is used for the transesterification reaction. As a reactive distillation column

2

Using. In this example, a perforated plate tray having a cross-sectional area per hole = about 1.5 cm ² and a number of holes = about 250 holes / m ² was used as an internal.

Reactive distillation and separation of by-product methanol were performed using a continuous multi-stage distillation column A shown in Fig. 1 and a continuous multi-stage distillation column B of Example 1 shown in Fig. 2 connected as shown in Fig. 3. I got it. Dimethyl carbonate 44 wt ^_0/0, phenol 49 mass ^_0/0, § - Sole 5.7 mass ^_0/0, Mechirufuwe - Le carbonate 1% by weight, methanol 0.3% by weight, the force becomes the raw material 1 continuous multi-stage distillation Liquid was continuously introduced from the upper inlet 21 of the tower A at a flow rate of 80.8 tons Zhr. The raw material 1 is introduced from the introduction port 20 and heated by the heat of the low boiling point reaction mixture (A) extracted from the upper part of the distillation column A by heat exchange and then sent to the introduction port 21.

T

It was. On the other hand, dimethyl carbonate 76 parts by mass ^_0/0, phenol 19.5 wt ^_0/0, § -. Sole 4 4 wt%, Mechirufue - Le carbonate 0.1 wt%, the raw material 2 lower introduction of said distillation column A comprising It was continuously introduced at a flow rate of 11 to 86 tons Zhr. The molar ratio of the raw materials introduced into the continuous multistage distillation column A was dimethyl carbonate Z phenol = 1.87. This raw material was substantially free of halogen (detection by ion chromatography). Lppb or less outside limits). The catalyst is Pb (OPh) so that the reaction solution is about 70 ppm.

2

It was introduced from the inlet 10 at the top of the distillation column A. Reactive distillation was continuously carried out under the conditions where the temperature at the bottom of the distillation column A was 233 ° C. and the pressure at the top of the column was 9.6 × 10 ⁵ Pa. After 24 hours, stable steady operation was achieved. The continuously withdrawn liquid at the bottom connected disconnect spout 25 force the unit 82.3 t Zhr of the distillation column A, Mechirufue - Rukabone over preparative is 10.1 mass ^_0/0, Jifue - Le The carbonate contained 0.27% by mass. The amount of methyl phenyl carbonate produced per hour was 8.3 tons (excluding the amount introduced into distillation column A, the actual amount produced was 7.5 tons Zhr), and the production of diphenyl carbonate per hour Production was found to be 0.22 tons. The combined selectivity of methyl phenol carbonate and diphenyl carbonate with respect to the reacted phenol was 99%.

[0053] A long-term continuous operation was performed under these conditions. After 500 hours, 2000 hours, 4000 hours, 5000 hours, 6000 hours, the production volume per hour is methylphenol carbonate. 8.3, 8.3, 8.3 8.3 centimeters, 8.3 centimeters, and the production per hour of diphenyl carbonate is 0.22 centimeters, 0.22 centimeters, 0.22 centimeters, 0.22 centimeters. 0.22%, and the combined selectivity of methyl and diphenyl carbonate is 99%, 99%, 99%, 99%, 99%, 99%, which is very stable. It was. In addition, the produced aromatic carbonate did not substantially contain halogen (lppb or less).

[0054] A low boiling point reaction mixture continuously extracted in the form of a gas from the top of the continuous multistage distillation column A (A

) Is reduced to 170 ° C by using heat exchange ^^ 27 to heat the raw material 1 above.

T

Let 85. The composition of the low boiling point reaction mixture (A) extracted at 2 tons Zhr is methanol 2

T

Mass ^_0/0, dimethyl carbonate 74 parts by mass ^_0/0, phenol 19.5 wt ^_0/0, § - sole 4.4 wt%, Mechirufue - was Le carbonate 0.1% by weight. The low boiling point reaction mixture (A) has a liquid temperature near the inlet 31 provided between the recovery part and the concentration part of the continuous multistage distillation column B.

T

After being brought to a close temperature, the distillation column B was continuously supplied from the inlet 31. Meanwhile, fresh dimethyl carbonate was continuously introduced from the inlet 41 at the bottom of the distillation column B at 2.53 tons Zhr. The distillation column B is continuously distilled and separated at a column bottom temperature of 226 ° C, a column top temperature of 155 ° C, and a reflux ratio of 3, and a low boiling point mixture (B) is discharged from the outlet 39 to 1.73 tons Zh

T

r, the high boiling point mixture (B) is continuously extracted from the extraction port 35 to 86 tons Zhr. It was. The high boiling point mixture (B) has a methanol content of 0.1% by mass or less.

B

The composition was the same as that of the raw material 2 of the continuous multistage distillation column A, and this was recycled and reused as the raw material 2.

[0055] The composition of the low boiling point mixture (B) is 97% by mass of methanol and 3% by mass of dimethyl carbonate.

T

%Met. The amount of methanol continuously distilled off was 1.68 tons Zhr. The low boiling point mixture (B) is reacted with ethylene carbonate to give dimethyl carbonate and ethyl acetate.

T

It was used as a raw material for producing lenglycol.

The operation of continuous multistage distillation column B was performed in accordance with the continuous operation of continuous multistage distillation column A, but the separation efficiencies after 500 hours, 2000 hours, 4000 hours, 5000 hours, and 6000 hours were the same as in the initial stage. It was stable.

[0056] [Example 4]

Using the same continuous multi-stage distillation column A and continuous multi-stage distillation column B as in Example 3, reactive distillation and by-product methanol were separated under the following conditions.

Dimethyl carbonate 33.3 weight ^_0/0, phenol 58.8 wt ^_0/0, § - sole 6.8 wt%, Mechirufue - Le carbonate 0.9 wt%, methanol 0.2% by weight, the raw material 1 consisting force From the inlet 20 through the heat exchanger 27, liquid was continuously introduced from the upper inlet 21 of the continuous multistage distillation column A at a flow rate of 86.2 tons Zhr. On the other hand, dimethyl carbonate 64.4% by weight, phenol 33.8 wt ^_0/0, § - Sole 1.3 mass ^_0/0, Mechirufue -. Le carbonate 0 4 wt%, the raw material 2 consisting of methanol 0.1 wt% Was continuously introduced from the lower inlet 11 of the distillation column A at a flow rate of 86.6 tons Zhr. The molar ratio of the raw materials introduced into the continuous multistage distillation column A was dimethyl carbonate / phenol = 1.1. The raw material contained substantially no halogen (less than the limit of detection by ion chromatography, lppb or less). The catalyst is Pb (OPh), and the distillation column A is adjusted so as to have about lOOppm in the reaction solution.

2

It was introduced from the upper inlet 10. Reactive distillation was continuously carried out under the conditions that the temperature at the bottom of the distillation column A was 230 ° C. and the pressure at the top of the column was 6.5 × 10 ⁵ Pa. After 24 hours, stable steady operation was achieved. In the liquid continuously extracted at 88 ton Zhr from the outlet 25 connected to the bottom of the distillation column A, 13.4 mass of methyl phenyl carbonate was obtained. %, Diphenol carbonate was contained in an amount of 0.7% by mass. The production amount of methylphenol carbonate per hour is 11.8 tons (the actual production amount excluding the amount introduced into the distillation column A is 10.7 tons Zhr), and the diphenyl carbonate production per hour Production was found to be 0.6 tons. The combined selectivity of methyl phenol carbonate and diphenol carbonate for the reacted phenol was 98%.

[0057] A long-term continuous operation was performed under these conditions. After 500 hours, 1000 hours, and 2000 hours, the production volume per hour is 1,8 tons, 11.8 tons, and 11.8 tons of methylphenol carbonate, and per hour of diphenyl carbonate. The production rate is 0.6 tons, 0.6 tons, and 0.6 tons, and the combined selectivity of methylphenol carbonate and diphenol carbonate is 98%, 98%, 98%, which is very It was stable. In addition, the produced aromatic strength boronate was substantially free of halogen (lppb or less).

[0058] <Separation of byproduct methanol from low boiling point reaction mixture (A)>

T

The low-boiling point reaction mixture (A) continuously extracted in gaseous form from the top of the continuous multistage distillation column A is heated to 161 ° C by using the heat to heat the raw material 1 in the heat exchange ^^ 27. Reduced

T

Let 85. The composition of the low boiling point reaction mixture (A) withdrawn at 4 tons Zhr is methanol 3

T

. 1 Mass ^_0/0, dimethyl carbonate 61 parts by mass ^_0/0, phenol 34.3 wt ^_0/0, § -. Sole 1 2 wt%, Mechirufue - was Le carbonate 0.2% by weight. The low boiling point reaction mixture (A) is a liquid near the inlet 31 provided between the recovery part and the concentration part of the continuous multistage distillation column B.

T

After being brought to a temperature close to the temperature, it was continuously supplied to the distillation column B from the inlet 31. On the other hand, fresh dimethyl carbonate was continuously introduced into the distillation column B at 3.98 ton Zhr from the inlet 51 in the fourth stage of the lower part of the concentration section. The distillation column B is continuously distilled and separated at a column bottom temperature of 213 ° C, a column top temperature of 138 ° C, and a reflux ratio of 2.89, and a low boiling point mixture (B) is formed.

T

From extraction port 39 to 2.78 tons Zhr, high boiling point mixture (B) from extraction port 35 to 86.6 tons

B

Each was continuously extracted with Zhr. The high boiling point mixture (B) has a methanol content.

B

Is 0.1 mass% or less, and the composition thereof is almost the same as the composition of the raw material 2 of the continuous multistage distillation column A, and this was recycled and reused as the raw material 2.

[0059] The composition of the low boiling point mixture (B) is 93.3 mass% methanol, dimethyl carbonate 6.7.

T

It was mass%. The amount of methanol continuously distilled off was 2.59 tons Zhr. . The low boiling point mixture (B) is reacted with ethylene carbonate to form dimethyl carbonate and

T

Used as a raw material for producing ethylene glycol.

The operation of continuous multi-stage distillation column B was performed in accordance with the continuous operation of continuous multi-stage distillation column A, but the separation efficiency after 500 hours, 1000 hours, and 2000 hours was the same as in the initial stage, and it moved stably. .

[0060] [Example 5]

Is performed reactive distillation in the same manner using the same continuous multi-stage distillation column A as in Example 3, methanol 1.5% by weight from the tower top withdrawal 26, dimethyl carbonate 81.9% by weight, phenol 12.4 wt ⁰ / _0, § - sole 3.9 mass ^_0/0, Mechirufue - consisting Le carbonate 0.3 wt% low boiling point reaction mixture (A) was withdrawn at 80.26 t ZHR. Low boiling point

T

The reaction mixture (A) was subjected to heat exchange 27 in the same manner as in Example 1 and the same continuous mixture as in Example 3 was obtained.

T

Continuously supplied from the inlet 31 between the collecting section and the concentrating section of the staged distillation column B, while fresh raw material consisting of 99% by mass of dimethyl carbonate and 1% by mass of methanol is in the 4th stage under the concentrating unit. It was continuously introduced into the distillation column B at 1.76 ton Zhr from the inlet 51 of the eye. In the distillation column B, distillation separation was continuously performed at a column bottom temperature of 219 ° C, a column top temperature of 151 ° C, and a reflux ratio of 6.74, and a low boiling point mixture (B) was extracted from the outlet 39 to 1.19 tons. High boiling point at Zhr

T

The mixture (B) was continuously withdrawn from the outlet 35 at 80.83 ton Zhr. The

B

The high boiling point mixture (B) has a methanol content of 0.1% by mass or less, which is a reactive distillation.

B

As a raw material of the above, it was recycled and reused in the continuous multistage distillation column A.

[0061] The composition of the low boiling point mixture (B) is 99% by mass of methanol and 1% by mass of dimethyl carbonate.

T

%Met. The amount of methanol continuously distilled off was 1.18 tons Zhr. The low boiling point mixture (B) is reacted with ethylene carbonate to give dimethyl carbonate and ethyl acetate.

T

It was used as a raw material for producing lenglycol.

[Example 6]

Reactive distillation was performed in the same manner using the same continuous multi-stage distillation column A as in Example 3, Tower top withdrawal 26 Methanol 2.8% by mass, dimethyl carbonate 61.0% by weight, phenol 26.4 wt ^_0/0, § - Sole 9.6 mass ^_0/0, Mechirufue - Le carbonate 0.2 wt% A low boiling point reaction mixture (A) consisting of was extracted at 57.45 ton Zhr. Low boiling point

T

Continuously supplied from the inlet 31 between the recovery section and concentrating section of the column distillation column B, while fresh raw materials consisting of 99.7 mass% of dimethyl carbonate and 0.3 mass% of methanol are the lower forces of the concentrating section It was continuously introduced into the distillation column B at a rate of 2.44 tons Zhr from the inlet 51 of the fourth stage. In the distillation column B, the bottom temperature is 215 ° C, the top temperature is 138 ° C, the reflux ratio is 4.4, and the distillation separation is continuously performed, and the low boiling point mixture (B) is extracted from the outlet 39 to 1.69 tons Zhr. And high boiling

T

The point mixture (B) was continuously withdrawn from the outlet 35 at 58.2 tons Zhr. The

B

The high boiling point mixture (B) has a methanol content of 0.08% by mass,

B

Recycled and reused in the continuous multistage distillation column A as a raw material.

[0063] The composition of the low boiling point mixture (B) is 94.9% by mass of methanol, dimethyl carbonate 5.1.

T

It was mass%. The amount of methanol continuously distilled off was 1.6 tons Zhr. The low boiling point mixture (B) is reacted with ethylene carbonate to form dimethyl carbonate and ester.

T

It was used as a raw material for producing tylene glycol.

The operation of continuous multistage distillation column B was performed in accordance with the continuous operation of continuous multistage distillation column A, but the separation efficiency after 500 hours and 1000 hours was the same as the initial stage and remained stable.

[0064] [Example 7]

Is performed reactive distillation in the same manner using the same continuous multi-stage distillation column A as in Example 3, methanol 3.0% by weight from the tower top withdrawal 26, dimethyl carbonate 62.8% by weight, phenol 28.0 wt ⁰ / _0, § - sole 6.1 mass ^_0/0, Mechirufue - consisting Le carbonate 0.1 wt% low boiling point reaction mixture (A) was withdrawn at 57.11 t ZHR. Low boiling point

T

It is continuously supplied from the inlet 31 between the recovery section and the concentrating section of the staged distillation column B, while fresh dimethyl carbonate also has a lower force of the concentrating section from the inlet 51 of the fourth stage at 2.8 tons Zhr. It was continuously introduced into the distillation column B. In the distillation column B, the bottom temperature was 213 ° C, the top temperature was 138 ° C, the reflux ratio was 2.89, and distillation separation was continuously performed, and the low boiling point mixture (B) was extracted. From outlet 39 to 1.84 tons Zhr, high boiling point mixture (B) is withdrawn from outlet 35 to 58.07 tons Zhr

B

Each was continuously extracted. The high boiling point mixture (B) has a methanol content of 0.

B

It was 09% by mass, and this was recycled in the continuous multistage distillation column A as a raw material for reactive distillation.

[0065] The composition of the low-boiling mixture (B) is 93.3 mass% methanol, dimethyl carbonate 6.7.

T

It was mass%. The amount of methanol continuously distilled off was 1.72 ton Zhr. The low boiling point mixture (B) is reacted with ethylene carbonate to form dimethyl carbonate and

T

Used as a raw material for producing ethylene glycol.

Industrial applicability

[0066] The present invention relates to alcohols produced as a by-product when an aromatic carbonate is continuously produced on an industrial scale of 1 ton or more per hour by a transesterification reaction between a dialkyl carbonate and an aromatic monohydroxy compound. The low boiling point reaction mixture containing alcohol can be suitably used as an industrial separation apparatus for separating alcohols.

Brief Description of Drawings

[0067] FIG. 1 is a schematic diagram showing an example of a continuous multistage distillation column A that performs reactive distillation, which is a preferred reaction system for performing the transesterification reaction of the present invention. An internal (for example, tray 6) with n stages is installed inside.

FIG. 2 is a schematic view showing an example of a continuous multistage distillation column which is an industrial separation apparatus for by-product alcohols of the present invention. Internal is installed inside. Internally, the collection unit (for example, tray 7) has n stages and the concentration unit (for example, tray 8) has n.

1 2

FIG. 3 is a schematic diagram showing a connection between reactive distillation and an apparatus for performing distillation separation of by-product alcohols of the present invention. 1: Gas outlet, 2: Liquid outlet, 3, 4: Inlet, 5: End plate, 6, 7, 8: Tray, SS: Recovery section, ES: Concentration section, L: Continuous multistage distillation column A Length (cm), D: inner diameter of continuous multistage distillation column A (cm), d: inner diameter of gas outlet of continuous multistage distillation column A (cm), d: continuous multistage

1 Inner diameter (cm) of the liquid outlet of the two-stage distillation column A, L: Length of the recovery section (cm) of the continuous multi-stage distillation column B, L: Length of the concentrating part of continuous multistage distillation column B (cm), D: Of the recovery part of continuous multistage distillation column B

twenty one

Diameter (cm), D: Inner diameter of concentrating part of continuous multistage distillation column B (cm), 10, 11, 20, 21, 31, 41,

2

51: Inlet, 22, 25, 32, 35, 39: Liquid outlet, 26, 36: Gas outlet, 24, 34, 3 8: Inlet, 23, 33, 27, 37: Heat exchange

Claims

The scope of the claims

Low-boiling point reaction containing alcohols by-produced in the continuous production of aromatic carbonates on an industrial scale of 1 ton or more per hour by transesterification of dialkyl carbonates with aromatic monohydroxy compounds Mixture force An apparatus for separating alcohols, which has an internal length L (cm) satisfying the following formulas (1) to (8), an inner diameter D (cm), and an internal number n of stages. Collection section, length L (cm), inner diameter D (cm), inside

2

Industrial separation equipment for by-product alcohols characterized;

500 <L ≤ 3000

1 formula (1)

100 <D ≤ 500 (2)

1

2 <L / Ό ≤ 30 (3)

1 1

10 <n ≤ 40 (4)

1

700 <L ≤ 5000 (5)

2

50 <D ≤ 400 (6)

2

10 <L / Ό ≤ 50 (7)

twenty two

35 <n ≤ 100 Equation (8).

[2] L, D, L ZD, n, L, D, L ZD, n of the continuous multistage distillation column are 800

1 1 1 1 1 2 2 2 2 2

≤L ≤2500, 120≤D ≤400, 5≤L / Ό ≤20, 13≤n≤25, 1500≤L ≤3500, 70≤D ≤200, 15≤L / Ό ≤30, 40≤n≤70 , L ≤ L, D

2 2 2 2 1 2

≤ D,

twenty one

The industrial separation apparatus for by-product alcohols according to claim 1, wherein

[3] The by-product alcohols according to claim 1 or 2, wherein the internal parts of the recovery part and the concentration part of the continuous multistage distillation column are a tray and Z or a packing, respectively. Industrial separation equipment.

[4] The industrial separation apparatus for by-product alcohols according to [3], wherein the internal parts of the recovery section and the concentration section of the continuous multistage distillation column are trays.

5. The industrial separation apparatus for by-product alcohols according to claim 4, wherein the tray is a perforated plate tray having a perforated plate portion and a downcomer portion.

6. The industrial separator for by-product alcohols according to claim 5, wherein the perforated plate tray has 100 to L000 holes per lm ² of the perforated plate portion. .

[7] The industrial separation apparatus for by-product alcohols according to claim 5 or 6, wherein a cross-sectional area per hole of the perforated plate tray is 0.5 to ⁵ cm ² .

[8] The steril exchange reaction is carried out by a reactive distillation method. The low boiling point reaction mixture is mixed with a top component having a concentration of the alcohols of 90% by mass or more and a content of the alcohols of 0.2%. % Of alcohols separated into the bottom components of the column, and the amount of the alcohols separated as the top components is 200 kg or more per hour. 8. Industrial separation apparatus for by-product alcohols as described in 1.

[9] The by-product alcohol industry according to claim 8, wherein the concentration of the alcohol in the top component is 95% by mass or more with respect to 100% by mass of the top component. Separation device.

[10] The by-product alcohols industry according to claim 8, wherein the concentration of the alcohols in the tower top component is 97% by mass or more with respect to 100% by mass of the tower top component. Separation device.

[11] The content of any one of claims 8 to 10, wherein the content of the alcohol in the column bottom component is 0.1% by mass or less with respect to 100% by mass of the column bottom component. The industrial separation apparatus for by-product alcohols according to one item.