KR100846330B1 - Industrial process for producing an aromatic carbonate - Google Patents

Abstract

The problem to be solved by the present invention is an alkylaryl carbonate obtained by the transesterification reaction of a dialkyl carbonate and an aromatic monohydroxy compound as a raw material, and using the continuous multi-stage distillation column, this raw material in a continuous multi-stage distillation column where a catalyst is present. When continuously supplying aromatic carbonates containing diaryl carbonate as the main product, the diaryl carbonate can be stably produced for a long time with high selectivity and high productivity at an industrial scale of 1 ton or more per hour. It is to provide a concrete method. Many proposals have been made regarding the production of aromatic carbonates by reactive distillation, but these are all small-scale, short-term, laboratory-level methods, and there is no disclosure of any specific method or apparatus for enabling industrial scale mass production. There was no. In the present invention, a specific continuous multi-stage distillation column is provided, and from an alkylaryl carbonate containing a specific amount of a dialkyl carbonate and an aromatic monohydroxy compound, a diaryl carbonate with high selectivity and high productivity at an industrial scale of 1 ton or more per hour There is provided a specific method for producing a stable for a long time.

Diaryl Carbonate, Alkylaryl Carbonate

Description

Method for industrially producing aromatic carbonates {INDUSTRIAL PROCESS FOR PRODUCING AN AROMATIC CARBONATE}

This invention relates to the industrial manufacturing method of aromatic carbonates. More specifically, the alkylaryl carbonate obtained by the transesterification reaction of the dialkyl carbonate and the aromatic monohydroxy compound is used as a raw material, and this raw material is an aromatic having a diaryl carbonate as the main product in a continuous multistage distillation column in which a catalyst is present. It is related with the method of industrially mass-producing the aromatic carbonates useful as a raw material of a transesterification polycarbonate by converting into carbonates.

Aromatic carbonates are important as raw materials for producing aromatic polycarbonates, which are the most in demand engineering plastics, without using toxic phosgene. As a manufacturing method of an aromatic carbonate, the method by reaction of an aromatic monohydroxy compound and phosgene is known from the past, and it has been examined variously in recent years. However, this method, in addition to the problem of using phosgene, contains an chlorine-based impurity that is difficult to separate in the aromatic carbonate produced by this method and cannot be used as a raw material of an aromatic polycarbonate as it is. This chlorine-based impurity significantly inhibits the polymerization reaction of the transesterification polycarbonate which is carried out in the presence of a trace amount of basic catalyst, so that, for example, even if 1 ppm is present, the polymerization can hardly proceed. Therefore, in order to use as a raw material of the transesterification polycarbonate, a sufficient washing process with a rare alkaline aqueous solution and hot water is required, and a multi-step cumbersome separation and purification process such as distillation and distillation is required. There are many problems to carry out this method on an economically reasonable industrial scale, such as a decrease in yield due to hydrolysis loss or distillation loss in the purification process.

On the other hand, the manufacturing method of aromatic carbonate by the transesterification reaction of a dialkyl carbonate and an aromatic monohydroxy compound is also known. However, these transesterification reactions are all equilibrium reactions. Moreover, since the equilibrium is extremely biased to the original system and the reaction rate is slow, the production of aromatic carbonates in industrial quantities in this way is carried out. It was very difficult. Several proposals have been made to improve this, most of which relate to the development of catalysts to speed up the reaction. Numerous metal compounds have been proposed as catalysts for this type of transesterification reaction. For example, compounds that produce Lewis acids or Lewis acids, such as transition metal halides (Patent Document 1: Japanese Patent Application Laid-open No. 51-105032, Japanese Patent Application Laid-open No. 56-123948, Japanese Patent Application Laid-open No. 56); -123949 (West German Patent Publication No. 2524812, Specification of British Patent No. 1495530, Specification of US Patent No. 4182726), Japanese Patent Application Laid-open No. 51-75044 (West Patent Publication No. 2552907, US Patent No. 4045464) Specifications), tin compounds such as organic tin alkoxides and organic tin oxides (Patent Document 2: Japanese Patent Application Laid-Open No. 54-48733 (West German Patent Application Publication No. 2736062), Japanese Patent Application Publication No. 54-63023) Japanese Patent Laid-Open No. 60-169444 (US Patent No. 4452110), Japanese Patent Laid-Open No. 60-169445 (US Pat. No. 4452704), Japanese Patent Laid-Open No. 62-277345, Japanese Laid Open Patent Publication No. Hei 1-265063), Salts and alkoxides of alkali metals or alkaline earth metals (see Patent Document 3: JP-A-57-176932), Lead Compounds (Patent Document 4: JP-A-57-176932, JP-A) 1-93560), complexes of metals such as copper, iron and zirconium (see Patent Document 5: JP-A-57-183745), Titanate esters (Patent Document 6: JP-A-58-) 185536 (US Patent No. 4410464), Japanese Unexamined Patent Application Publication No. Hei 1-265062, A mixture of Lewis acid and protonic acid (Patent Document 7: Japanese Patent Application Laid-Open No. 60-173016 (US Patent No. 4609501) ), Sc, Mo, Mn, Bi, Te and other compounds (see Patent Document 8: Japanese Patent Application Laid-open No. Hei 1-265064), ferric acetate (Patent Document 9: Japanese Patent Laid-Open No. 61-172852) And the like). However, since the development of the catalyst alone cannot solve the problem of disadvantageous equilibrium, there are a lot of problems to be studied, including the examination of the reaction method, in order to obtain an industrial production method for mass production.

In addition, attempts have been made to improve the yield of aromatic carbonates by shifting the equilibrium to production measurement as far as possible by studying the reaction system. For example, in the reaction of dimethyl carbonate and phenol, by-product methanol is distilled off by azeotropic with an azeotropic agent (Patent Document 10: Japanese Patent Application Laid-Open No. 54-48732 (West German Patent) (See Japanese Patent Application Laid-Open No. 736063, US Pat. No. 4,425,373)), A method of adsorbing and removing byproduct methanol with a molecular sieve (Patent Document 11: JP-A-58-185536 (US Pat. No. 410464) ) Is proposed. Moreover, the method of distilling off unreacted raw material which is evaporating simultaneously while separating by-product alcohol from a reaction mixture by the apparatus which provided the distillation column in the upper part of a reactor is also proposed (patent document 12: Example of Unexamined-Japanese-Patent No. 56-123948 (Specification of US Patent No.4182726), Example of Unexamined-Japanese-Patent No. 56-25138, Unexamined-Japanese-Patent No. 60-169444 (Specification of US Patent 4455110) Examples, Japanese Unexamined Patent Application Publication No. 60-169445 (US Pat. No. 4452704), Japanese Unexamined Patent Publication No. 60-173016, US Patent No. 4605501, and See Examples in US Pat. No. 61-172852, Examples in Japanese Patent Laid-Open No. 61-291545, and Examples in Japanese Patent Laid-Open No. 62-277345.

However, their reaction mode is basically a batch mode or a conversion mode. The improvement of the reaction rate by the development of the catalyst is also limited to such a transesterification reaction, and since the reaction rate is slow, it was considered that the batch method is preferable to the continuous method. Among them, a continuous stirred tank reactor (CSTR) system having a distillation column at the top of the reactor as a continuous system is also proposed, but the reaction rate is slow and the gas-liquid interface of the reactor is small with respect to the liquid capacity. There is a problem that the reaction rate cannot be increased. Therefore, it is difficult to achieve the purpose of producing aromatic carbonate continuously and in large quantities in a long and stable manner in this way, and there are more problems to be solved in order to achieve economically reasonable industrial practice.

The present inventors continuously supply a dialkyl carbonate and an aromatic hydroxy compound to a multistage distillation column, continuously react in the column in which the catalyst was present, and continuously distill the low boiling point component containing alcohol by-produced by distillation. Reaction distillation which extracts the component containing the produced | generated alkylaryl carbonate from the bottom of a tower with extraction (patent document 13: Unexamined-Japanese-Patent No. 3-291257), and a continuous multistage distillation column of alkylaryl carbonate Was supplied to the reactor and continuously reacted in the column in which the catalyst was present, and the low boiling component containing the byproduct dialkyl carbonate was continuously extracted by distillation, and the component containing the produced diaryl carbonate was removed from the bottom of the tower. Reaction distillation method which extracts (refer patent document 14: Unexamined-Japanese-Patent No. 4-9358), these reactions are carried out A reaction distillation method (see Patent Document 15: Japanese Patent Application Laid-open No. 4-211038), which continuously produces diaryl carbonate while efficiently recycling by-product dialkyl carbonate by using a continuous multi-stage distillation column, and a dialkyl carbonate The aromatic hydroxy compound and the like are continuously supplied to the multi-stage distillation column, and the liquid flowing down the column is extracted from the side outlet formed at the middle end and / or the bottom end of the distillation column, and is formed outside the distillation column. A reaction distillation method in which the reaction is carried out both in the reactor and in the distillation column by introducing into the reactor and introducing the reaction into a circulation inlet formed at an upper stage than the stage having the outlet. Japanese Unexamined Patent Publication No. Hei 4-224547, Japanese Unexamined Patent Application Publication No. Hei 4-230242, and Japanese Unexamined Patent Application Publication No. Hei 4-235951)). And a le exchange reaction developed reactive distillation for carrying out the reaction and the distillation separation in a continuous multi-stage distillation column at the same time, the first time disclosed in the world that a reactive distillation system is useful for such a transesterification reaction.

These reaction distillation methods proposed by the present inventors are the first to enable efficient and continuous production of aromatic carbonates, and since then, many of the same reactive distillation methods based on these disclosures have been proposed. Reference Documents 17 to 32; Patent Document 17: International Publication No. 00/18720 (Specification of US Patent No. 5362901); Patent Document 18: Italian Patent Publication No. 01255746; Patent Document 19: Japanese Patent Application Laid-Open No. 6-9506 (European Patent 0560159, U.S. Patent No. 5302965); Patent Document 20: Japanese Patent Application Laid-Open No. 6-41022 (European Patent 0572870 Specification, US Patent No. 5362901 Specification); Patent Document 21: Japanese Patent Application Publication Japanese Patent Application Laid-open No. Hei 6-157424 (European Patent No. 0582931, US Patent No. 5334742), Japanese Patent Application Laid-Open No. 6-184058 (European Patent No. 0582930, US Patent No. 5344954) C) Patent Document 22: Japanese Patent Application Laid-Open No. 7-304713; Patent Document 23: Japanese Patent Application Laid-Open No. 9-40616; Patent Document 24: Japanese Patent Application Laid-Open No. 9-59225; Patent Document 25: Japan Japanese Patent Application Laid-Open No. 9-110805; Patent Document 26: Japanese Patent Application Laid-Open No. 9-165357; Patent Document 27: Japanese Patent Application Laid-Open No. 9-173819; Patent Document 28: Japanese Patent Application Laid-Open No. 9-176094 Japanese Patent Laid-Open No. 2000-191596, Japanese Patent Laid-Open No. 2000-191597; Patent Document 29: Japanese Patent Laid-Open No. 9-194436 (European Patent 0785184, US Patent No. 5567567); Patent Document 30 International Publication No. 00/18720 (U.S. Patent No. 6,026,42) Patent Document 31: Japanese Patent Application Laid-Open No. 2001-64234, Japanese Patent Application Laid-Open No. 2001-64235; Patent Document 32: International Publication No. 02/40439 (US Pat. No. 6,684,94, US Pat. No. 6,659,95, US Pat.

In addition, in the reaction distillation method, the present applicant is a method for stably producing a high-purity aromatic carbonate for a long time without requiring a large amount of catalyst, after reacting a high boiling point material containing a catalyst component with a working substance. Separation and recycling of the catalyst component (see Patent Document 31: Japanese Patent Laid-Open No. 2001-64234, Japanese Patent Laid-Open No. 2001-64235), or a polyvalent aromatic hydroxy compound in the reaction system in a mass ratio of 2.0 to the catalyst metal. A method (see Patent Document 32: International Publication No. 02/40439 (US Pat. No. 6,684,94, US Pat. No. 6,684,95, US Pat. No. 6,069,611 specification)) was proposed. Moreover, the present inventors also proposed the method of making diphenyl carbonate by the reaction distillation method using 70-99 mass% of the phenol by-produced in a superposition | polymerization process as a raw material of an aromatic polycarbonate (patent Document 33: See International Publication No. 97/11049 (European Patent 0855384, US Pat. No. 5872275).

However, all prior literature suggesting the production of aromatic carbonates by these reactive distillation methods does not disclose any specific method or apparatus for enabling industrial scale mass production (e.g., more than 1 ton per hour). There is no technology to suggest them. For example, the height (H: cm), diameter (D: cm), number of stages (n: n), and reaction raw material introduction amount of the reaction distillation column disclosed to prepare diphenyl carbonate (DPC) from methylphenyl carbonate (MPC) The description regarding (Q: kg / hr) is as follows.

H: cm D: cm Singular: n Q: kg / hr Patent Literature 400 7.5 - 4.2 14 600 25 20 23.3 15 305 5-10 15 + rule filler 0.6 21 400 8 50 <0.6 23 200 4 - 0.8 24 - 5 25 0.7 28 600 25 20 31 33 600 25 20 31 34 600 - 20 22.3 35

[Patent Document 34] See Japanese Laid-Open Patent Publication No. Hei 11-92429 (European Patent No. 1016648, US Patent No. 6222210).

[Patent Document 35]: Japanese Patent Application Laid-Open No. 9-255772 (see European Patent 0892001 Specification and US Patent No. 5747609 Specification)

That is, the largest of the continuous multi-stage distillation columns used in carrying out this reaction by the reaction distillation method is disclosed in the patent documents 15, 33, 34 by the present applicant. Thus, the maximum value of each condition in the continuous multistage distillation column disclosed for this reaction was H = 600 cm, D = 25 cm, n = 50 (Patent Document 23), Q = 31 kg / hr, and diphenyl The yield of carbonate was only about 6.7 kg / hr, not on an industrial scale.

Disclosure of the Invention

Problems to be Solved by the Invention

The problem to be solved by the present invention is a continuous multi-stage distillation column in which a catalyst is present using a continuous multi-stage distillation column using an alkylaryl carbonate obtained by a transesterification reaction of a dialkyl carbonate and an aromatic monohydroxy compound as a raw material. In the continuous production of aromatic carbonates containing diaryl carbonate as a main product, the diaryl carbonate can be stably produced for a long time with high selectivity and high productivity on an industrial scale of 1 ton or more per hour. Is to provide a specific method.

Means to solve the problem

Since the present inventors have disclosed a method for producing aromatic carbonates using a continuous multi-stage distillation column, many proposals have been made regarding a method for producing aromatic carbonates by a reactive distillation method, but these are all small and short-term laboratory level methods. However, no specific method or apparatus has been disclosed to enable industrial mass production. In addition, there was no disclosure of their contents, methods, and apparatuses necessary for industrial use of raw materials containing dialkyl carbonates which were considered to be disadvantageously balanced. Therefore, the present inventors have repeatedly studied to find out a specific method for producing long-term stable aryl carbonate with high selectivity and high productivity at an industrial scale of 1 ton or more per hour. It was.

That is, in the first aspect of the present invention,

1.A method for producing aromatic carbonates using, as a raw material, an alkylaryl carbonate obtained by a transesterification reaction of a dialkyl carbonate and an aromatic monohydroxy compound as a raw material,

(i) continuously feeding the raw materials into a continuous multi-stage distillation column in which a catalyst is present;

(ii) reacting the raw materials to produce a dialkyl carbonate and a diaryl carbonate,

(iii) continuously extracting the low boiling reaction mixture containing the resulting dialkyl carbonate from the top of the column into the gas phase, and continuously pouring the high boiling reaction mixture containing the diaryl carbonate from the bottom of the column into the liquid phase. Including the process of extraction,

(a) The raw material continuously supplied into the continuous multistage distillation column contains 5 to 38 mass% of the dialkyl carbonate and 5 to 61 mass% of the aromatic monohydroxy compound, based on the mass of the raw material,

(b) The continuous multistage distillation column has a hard plate portion above and below a cylindrical trunk portion having a length L (cm) and an inner diameter D (cm), and has an internal having a number n in the interior. A liquid having an internal diameter d ₂ (cm) at a gas outlet, a tower bottom, or a lower portion of a tower close thereto having a structure, and having an inner diameter d ₁ (cm) at the top of the tower or near the tower. Having at least one inlet at the top and / or middle portion of the tower below the outlet, the gas outlet, and at least one inlet at the bottom of the tower above the liquid outlet;

(1) Length L (cm) satisfy | fills Formula (1),

      1500 ≤ L ≤ 8000 (1)

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

      100 ≤ D ≤ 2000 (2)

(3) The ratio between the length L (cm) and the inner diameter D (cm) of the tower satisfies the formula (3),

        2 ≤ L / D ≤ 40 (3)

(4) The singular n satisfies the expression (4),

       10 ≤ n ≤ 80 (4)

(5) The ratio between the inner diameter D (cm) of the tower and the inner diameter d ₁ (cm) of the gas outlet port satisfies the formula (5),

2 ≤ D / d ₁ ≤ 15 (5)

(6) the ratio between the inner diameter D (cm) of the tower and the inner diameter d ₂ (cm) of the liquid outlet port satisfies the formula (6),

5 ≤ D / d ₂ ≤ 30 (6)

Characterized in that,

2. The process according to item 1, wherein distillation is performed simultaneously in the step (ii),

3. The aromatic carbonates containing diaryl carbonate as a main product are continuously produced, and the production method of the said diaryl carbonate is 1 ton or more per hour, The method of the preceding paragraph 1 or 2 characterized by the above-mentioned.

To provide.

Moreover, in another aspect of the manufacturing method which concerns on this invention,

4. Using alkylaryl carbonate obtained by transesterification of dialkyl carbonate and aromatic monohydroxy compound as a raw material, this raw material is continuously supplied into a continuous multi-stage distillation column in which a catalyst is present, and reaction and distillation are carried out in the column. The reaction distillation method is carried out at the same time to continuously extract the low boiling point reaction mixture containing the produced dialkyl carbonate from the top of the column into the gas phase and continuously extract the high boiling point reaction mixture containing the diaryl carbonate from the bottom of the column into the liquid phase. By continuously producing aromatic carbonates containing diaryl carbonate as a main product,

(a) The raw material continuously supplied into the continuous multistage distillation column contains 5-38 mass% of the dialkyl carbonate and 5-61 mass% of the aromatic monohydroxy compound, based on the mass of the raw material,

(b) The continuous multi-stage distillation column has a structure having a hard plate portion above and below a cylindrical trunk portion having a length L (cm) and an inner diameter D (cm), and having an internal having a number n inside thereof, Gas outlet of inner diameter d ₁ (cm) at the top of the near tower, liquid outlet of inner diameter d ₂ (cm) at the bottom of the tower or the bottom of the tower close thereto, upper and / or middle of the tower as lower than the gas outlet Having one or more inlet in the part, one or more inlet in the lower part of the tower as upper part than the liquid outlet,

(1) Length L (cm) satisfy | fills Formula (1),

      1500 ≤ L ≤ 8000 (1)

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

      100 ≤ D ≤ 2000 (2)

(3) The ratio between the length L (cm) and the inner diameter D (cm) of the tower satisfies the formula (3),

        2 ≤ L / D ≤ 40 (3)

(4) The singular n satisfies the expression (4),

       10 ≤ n ≤ 80 (4)

(5) The ratio between the inner diameter D (cm) of the tower and the inner diameter d ₁ (cm) of the gas outlet port satisfies the formula (5),

2 ≤ D / d ₁ ≤ 15 (5)

(6) the ratio between the inner diameter D (cm) of the tower and the inner diameter d ₂ (cm) of the liquid outlet port satisfies the formula (6),

5 ≤ D / d ₂ ≤ 30 (6)

Industrial production method of aromatic carbonates having a diaryl carbonate as a main product, characterized in that

5. The method according to item 4, wherein the production amount of diaryl carbonate is 1 ton or more per hour,

6. The raw material further contains 0.5-15 mass% alkylaryl ether with respect to the mass of this raw material, The method in any one of the preceding paragraph 1-5 characterized by the above-mentioned.

7. The d ₁ and the d ₂ are represented by equation (7),

1 ≤ d ₁ / d ₂ ≤ 6 (7)

Satisfying the method according to any one of claims 1 to 6,

8. L, D, L / D, n, D / d ₁ and D / d ₂ of the continuous multi-stage distillation column are 2000 ≤ L ≤ 6000, 150 ≤ D ≤ 1000, 3 ≤ L / D ≤ 30, 15 ≤ n ≤ 60, 2.5 ≤ D / d ₁ ≤ 12, 7 ≤ D / d ₂ ≤ 25, the method according to any one of the preceding claims 1 to 7,

9. L, D, L / D, n, D / d ₁ , D / d ₂ of the continuous multi-stage distillation column are 2500 ≤ L ≤ 5000, 200 ≤ D ≤ 800, 5 ≤ L / D ≤ 15, 20 ≤ n ≤ 50, 3 ≤ D / d ₁ ≤ 10, 9 ≤ D / d ₂ ≤ 20, the method according to any one of the preceding claims 1 to 8,

10. The method according to any one of items 1 to 9, wherein the continuous multistage distillation column is a distillation column having a packing and a tray as its internal.

11. The continuous multi-stage distillation column is a distillation column having a packing material at the top and a tray at the bottom thereof as the internal, wherein the method according to item 10,

12. The method according to item 9 or 10, wherein the filling of the internal is a regular filling,

13. The method according to item 10 or 11 above, wherein the tray of the internal is a perforated plate tray having a perforated plate portion and a downcomer portion,

14. The method according to item 10 or 11 above, wherein the filling of the internal is one or more regular fillings, and the tray is a perforated plate tray having a perforated plate portion and a downcomer portion.

15. The rule fillings are Melapak, Gempak, TECHNO-PAK, FLEXI-PAK, a Sulzer packing, a Goodroll packing, The method according to the preceding item 12 or 14, wherein the method is at least one selected from a grititch grid,

16. The method according to item 13 or 14, wherein the porous plate tray has 100 to 1000 holes per 1 m 2 of the porous plate portion.

17. The method according to any one of items 13, 14 and 16, wherein the cross-sectional area per hole in the perforated plate tray is 0.5 to 5 cm 2.

18. The regular filler is at least one selected from melapack, gumpack, technopack, flexipack, surgery packing, good roll packing, and grit grid, and the perforated plate tray is 100 to 1000 per square meter of the perforated plate portion. Having a number of holes, and having a cross-sectional area of 0.5 to 5 cm 2 per hole in the perforated plate tray, the method according to item 14,

To provide.

Moreover, in the 2nd aspect of this invention,

19. Aromatic carbonates produced by the method according to any one of items 1 to 18 and having a halogen content of 0.1 ppm or less,

To provide.

Effects of the Invention

By implementing this invention, it is 95% or more, Preferably it is 97% or more, using the alkyl aryl carbonate containing the specific amount of the dialkyl carbonate and aromatic monohydroxy compound which are obtained from a dialkyl carbonate and an aromatic monohydroxy compound, respectively. More preferably at least 99%, at least on an industrial scale, on an industrial scale at least 1 tonne per hour, preferably at least 2 tonnes per hour, more preferably at least 3 tonnes per hour, at a high selectivity of at least 99%. It has been found that for a long time it is possible to stably produce at least 3000 hours, more preferably at least 5000 hours. The diaryl carbonate obtained by separating and purifying aromatic carbonates containing, as a main component, the diaryl carbonate obtained in the present invention by distillation or the like is of high purity, and is a raw material of a transesterification polycarbonate, a polyester carbonate, or the like. It is useful as raw materials, such as an isocyanate and a urethane. In this invention, since the raw material and catalyst which do not contain a halogen are used normally, the halogen content of the obtained diaryl carbonate is 0.1 ppm or less, Preferably it is 10 ppb or less, More preferably, it is 1 ppb or less.

Implement the invention  Best form for

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated concretely.

Dialkyl carbonate used in order to obtain the alkylaryl carbonate which is a raw material of this invention is represented by General formula (8).

R ¹ OCOOR ¹ (8)

Here, R <^1> represents a C1-C10 alkyl group, a C3-C10 alicyclic group, and a C6-C10 aralkyl group. Such R ¹ is, for example, methyl, ethyl, propyl (isomer), allyl, butyl (isomer), butenyl (isomer), pentyl (isomer), hexyl (isomer), heptyl (isomer) Alkyl groups such as octyl (isomer), nonyl (isomer), decyl (isomer) and cyclohexylmethyl; Alicyclic groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl; And aralkyl groups such as benzyl, phenethyl (isomers), phenylpropyl (isomers), phenylbutyl (isomers) and methylbenzyl (isomers). Moreover, in these alkyl groups, alicyclic groups, and aralkyl groups, they may be substituted by other substituents, for example, a lower alkyl group, a lower alkoxy group, a cyano group, a halogen, etc., and may have an unsaturated bond.

Examples of the dialkyl carbonate having R ¹ include dimethyl carbonate, diethyl carbonate, dipropyl carbonate (isomer), diallyl carbonate, dibutenyl carbonate (isomer), dibutyl carbonate (isomer), Dipentylcarbonate (isomer isomer), dihexylcarbonate (isomer isomer), diheptylcarbonate (isomer isomer), dioctylcarbonate (isomer isomer), dinonylcarbonate (isomer isomer), didecylcarbonate (isomer isomer), dicyclo Pentyl carbonate, dicyclohexyl carbonate, dicycloheptyl carbonate, dibenzyl carbonate, diphenethyl carbonate (isomer isomer), di (phenylpropyl) carbonate (isomer isomer), di (phenylbutyl) carbonate (isomer isomer), di (chloro Benzyl) carbonate (each isomer), di (methoxybenzyl) carbonate (each isomer), di (methoxymethyl) carbonate, di (methoxyethyl) carbonate (each tooth Adult), di (chloroethyl) carbonate (each isomer), di (cyanoethyl) carbonate (each isomer), and the like.

Among them, preferably used in the present invention is a dialkyl carbonate composed of an alkyl group having 4 or less carbon atoms, wherein R ¹ does not contain a halogen, and particularly preferred is dimethyl carbonate. Among the preferred dialkyl carbonates, more preferred are dialkyl carbonates prepared substantially free of halogen, for example, alkylene carbonate free of substantially halogen and alcohol substantially free of halogen. It is manufactured from.

The aromatic monohydroxy compound used by this invention is represented by following General formula (9), Any thing may be sufficient if the hydroxyl group couple | bonded with the aromatic group directly.

Ar ¹ OH (9)

Ar ¹ represents an aromatic group having 5 to 30 carbon atoms. As an aromatic monohydroxy compound which has such Ar <^1> , For example, Phenol; Cresol (isomer), xylenol (isomer), trimethylphenol (isomer), tetramethylphenol (isomer), ethylphenol (isomer), propylphenol (isomer), butylphenol (isomer), Diethylphenol (isomer isomer), methylethylphenol (isomer isomer), methylpropylphenol (isomer isomer), dipropylphenol (isomer isomer), methylbutylphenol (isomer isomer), pentylphenol (isomer isomer), hexylphenol ( Various alkylphenols such as each isomer) and cyclohexylphenol (each isomer); Various alkoxyphenols such as methoxy phenol (isomer) and ethoxy phenol (isomer); Arylalkyl phenols such as phenylpropyl phenol (isomer); Naphthol (isomers) and various substituted naphthols; Heteroaromatic monohydroxy compounds, such as hydroxypyridine (isomer isomer), hydroxycoumarin (isomer isomer), and hydroxyquinoline (isomer isomer), etc. are used.

Among these aromatic monohydroxy compounds, preferably used in the present invention is an aromatic monohydroxy compound consisting of Ar ¹ having an aromatic group having 6 to 10 carbon atoms, and particularly preferably phenol. Moreover, what is preferably used in this invention among these aromatic monohydroxy compounds is what does not contain a halogen substantially.

The amount ratio of the dialkyl carbonate and aromatic monohydroxy compound used for obtaining the alkylaryl carbonate which is a raw material in this invention should be 0.4-4 in molar ratio with respect to an aromatic monohydroxy compound with respect to a dialkyl carbonate. Outside this range, the amount of unreacted residual amount increases with respect to the required amount of the target alkylaryl carbonate, which is inefficient, and requires a large amount of energy to recover them. In this sense, the molar ratio is preferably 0.5 to 3, more preferably 0.8 to 2.5, and still more preferably 1.0 to 2.0.

In the present invention, one or more tonnes of diaryl carbonates are continuously produced per hour. For this purpose, the alkylaryl carbonates continuously fed for this time are usually 5 P with respect to the amount of diaryl carbonates to be produced (P tonnes / hr). Ton / hr, preferably 3 P ton / hr, more preferably 2 P ton / hr. In more preferable cases, it can be made less than 1.8P ton / hr.

The alkylaryl carbonate used as a raw material in this invention should contain a specific amount of dialkyl carbonate and an aromatic monohydroxy compound. In the present invention, a reaction mainly converted to diaryl carbonate and dialkyl carbonate occurs by disproportionation reaction which is a transesterification reaction between two alkyl aryl carbonate molecules. Since this reaction is an equilibrium reaction, using a raw material containing a dialkyl carbonate as a product was considered to be disadvantageous in chemical equilibrium. However, in the case of using the continuous multi-stage distillation column of the present invention, even if the raw material contains 5 to 38% by mass of the dialkyl carbonate and 5 to 61% by mass of the aromatic monohydroxy compound based on the mass of the raw material. Surprisingly little was found. More preferable content of the dialkyl carbonate is 10 to 35% by mass, still more preferably 15 to 32% by mass. Moreover, content of the more preferable aromatic monohydroxy compound is 10-58 mass%, More preferably, it is 15-55 mass%.

The reaction between the diaryl carbonate and the dialkyl carbonate, which is the reverse reaction of the reaction, has a large equilibrium constant and a fast reaction rate. Therefore, the use of a raw material containing dialkyl carbonate as a product in a batch type reaction system having a small gas-liquid system area is prone to reverse reaction, which is very disadvantageous in terms of chemical equilibrium for producing a diaryl carbonate. It is easy to see. Moreover, in the small-scale reaction distillation system, since the residence time of a reaction liquid is generally short, using the raw material containing the dialkyl carbonate which is a product has little decrease in these concentrations in a reaction liquid, and diaryl carbonate It is obvious that chemical equilibrium is also disadvantageous in the preparation of.

However, using the continuous multi-stage distillation column of the present invention has surprisingly been found to have almost no adverse effects. The reason for this is unclear, but this effect was first discovered by a long-term continuous stable operation using the industrial multi-stage distillation column of the present invention.

Moreover, the raw material of this invention may contain the compound produced by this process and / or another process, and reaction by-products, for example, alkylaryl ether and high boiling point by-product. It turned out that the raw material containing 0.5-15 mass% of alkylaryl ethers is preferable in implementing this invention. The range with more preferable alkylaryl ether content in a raw material is 2-12 mass%, More preferably, it is 4-10 mass%.

Therefore, in the present invention, when diphenyl carbonate is produced using, for example, methylphenyl carbonate obtained by transesterification of dimethyl carbonate and phenol, the amount of dimethyl carbonate and phenol in the raw material is as much as the above-mentioned amount. It is preferable to contain, and it is preferable to contain the anisole which is a reaction byproduct by the above-mentioned quantity. Moreover, the diphenyl carbonate etc. may contain the denatured high boiling by-product.

The aromatic carbonates produced in the present invention refer to aromatic carbonates containing, as main components, diaryl carbonates obtained by transesterification of alkylaryl carbonates. In this transesterification reaction, the disproportionation reaction which is a reaction in which the alkoxy group of an alkylaryl carbonate exchanges with the aryloxy group of the aromatic monohydroxy compound which exists in a system, and leaves alcohol, and the transesterification reaction between two alkylaryl carbonate molecules. Reaction is converted to diaryl carbonate and dialkyl carbonate. In the present invention, disproportionation reaction of alkylaryl carbonate occurs mainly. In the present invention, a raw material or a catalyst containing no halogen can be used, and in this case, since the aromatic carbonate mainly composed of the diaryl carbonate produced contains no halogen, the polycarbonate is produced by transesterification. It is important as a raw material at the time of manufacture. That is, since the diaryl carbonate separated and purified by distillation or the like of the aromatic carbonate mainly composed of the diaryl carbonate obtained in the present invention contains no halogen in high purity, it is aromatic by transesterification with an aromatic dihydroxy compound. It is very useful as a raw material for producing polycarbonate.

Moreover, the alkylaryl carbonate used as a raw material in this invention should contain a fixed amount of dialkyl carbonate and an aromatic monohydroxy compound as mentioned above, Moreover, the compound produced in this process and / or another process, A reaction product, for example, alcohols, alkylaryl ethers or diaryl carbonates may be contained. It is also a preferable method to make it the raw material of this invention as it is, without isolate | separating an unreacted substance or a catalyst from the transesterification reaction mixture of dialkyl carbonate and an aromatic monohydroxy compound. Moreover, when it is industrially performed like this invention, the dialkyl carbonate and aromatic monohydroxy compound used in order to obtain the alkylaryl carbonate which is a raw material of this invention are the dialkyl carbonate and aromatic monohydride newly introduced into a reaction system. In addition to the oxy compounds, it is preferred to use those recovered in this or / and other processes.

As a catalyst used by this invention, the same thing as the catalyst used in order to obtain the alkylaryl carbonate which is chosen from the following compound and is a raw material, for example may be sufficient. Preferably, the catalyst used for the reaction of the dialkyl carbonate and the aromatic monohydroxy compound is used as it is without separation.

<Lead _{compounds> PbO, PbO 2, Pb 3} O 4 , etc. of the oxidation napryu; Lead sulfides such as PbS and Pb ₂ S; Lead hydroxides such as Pb (OH) ₂ and Pb ₂ O ₂ (OH) ₂ ; Lead acid salts such as Na ₂ PbO ₂ , K ₂ PbO ₂ , NaHPbO ₂ , and KHPbO ₂ ; Lead acid salts such as Na ₂ PbO ₃ , Na ₂ H ₂ PbO ₄ , K ₂ PbO ₃ , K ₂ [Pb (OH) ₆ ], K ₄ PbO ₄ , Ca ₂ PbO ₄ , and CaPbO ₃ ; Lead carbonates and basic salts thereof such as PbCO ₃ and 2PbCO ₃ .Pb (OH) ₂ ; Lead salts of organic acids such as Pb (OCOCH ₃ ) ₂ , Pb (OCOCH ₃ ) ₄ , and Pb (OCOCH ₃ ) ₂ .PbO.3H ₂ O, carbonates and basic salts thereof; Organic lead compounds such as Bu ₄ Pb, Ph ₄ Pb, Bu ₃ PbCl, Ph ₃ PbBr, Ph ₃ Pb (or Ph ₆ Pb ₂ ), Bu ₃ PbOH, Ph ₃ PbO (Bu is a butyl group, Ph is a phenyl group) Is represented.); Alkoxy lead and aryloxy lead such as Pb (OCH ₃ ) ₂ , (CH ₃ O) Pb (OPh) and Pb (OPh) ₂ ; Alloys of lead such as Pb-Na, Pb-Ca, Pb-Ba, Pb-Sn, and Pb-Sb; Lead minerals such as fluoride and island zinc, and hydrates of these lead compounds;

<Compound of copper group metal> CuCl, CuCl ₂ , CuBr, CuBr ₂ , CuI, CuI ₂ , Cu (OAc) ₂ , Cu (acac) ₂ , copper olefin acid, Bu ₂ Cu, (CH ₃ O) ₂ Cu, Salts and complexes of copper group metals such as AgNO ₃ , AgBr, silver picroic acid, AgC ₆ H ₆ ClO ₄ , [AuC≡CC (CH ₃ ) ₃ ] n, [Cu (C ₇ H ₈ ) Cl] _4, etc. Acetyl acetone chelate ligands.);

<Complex of Alkali Metal> Complexes of alkali metals such as Li (acac) and LiN (C ₄ H ₉ ) ₂ ;

<Complex of Zinc> Complexes of zinc such as Zn (acac) ₂ ;

<Cadmium Complex> Cadmium complexes such as Cd (acac) ₂ ;

<Compound of iron group metal> Fe (C ₁₀ H ₈ ) (CO) ₅ , Fe (CO) ₅ , Fe (C ₄ H ₆ ) (CO) ₃ , Co (mesitylene) ₂ (PEt ₂ Ph) ₂ , CoC Complexes of iron group metals such as ₅ F ₅ (CO) ₇ , Ni-π-C ₅ H ₅ NO, and ferrocene;

<Zirconium Complex> Zirconium complexes such as Zr (acac) ₄ and zirconocene;

<Lewis Copper Compound> AlX ₃ , TiX ₃ , TiX ₄ , VOX ₃ , VX ₅ , ZnX ₂ , FeX ₃ , SnX ₄ (where X is a halogen, acetoxy group, alkoxy group or aryloxy group). Lewis acids and transition metal compounds which generate Lewis acids;

<Organic Tin Compound> (CH ₃ ) ₃ SnOCOCH ₃ , (C ₂ H ₅ ) ₃ SnOCOC ₆ H ₅ , Bu ₃ SnOCOCH ₃ , Ph ₃ SnOCOCH ₃ , Bu ₂ Sn (OCOCH ₃ ) ₂ , Bu ₂ Sn (OCOC ₁₁ H ₂₃ ) ₂ , Ph ₃ SnOCH ₃ , (C ₂ H ₅ ) ₃ SnOPh, Bu ₂ Sn (OCH ₃ ) ₂ , Bu ₂ Sn (OC ₂ H ₅ ) ₂ , Bu ₂ Sn (OPh) ₂ , Ph ₂ Sn Organic tin compounds such as (OCH ₃ ) ₂ , (C ₂ H ₅ ) ₃ SnOH, Ph ₃ SnOH, Bu ₂ SnO, (C ₈ H ₁₇ ) ₂ SnO, Bu ₂ SnCl ₂ , BuSnO (OH);

Metal containing compounds, such as these, are used as a catalyst. These catalysts may be solid catalysts fixed in a multi-stage distillation column or soluble catalysts dissolved in the reaction system.

Of course, these catalyst components may be reacted with organic compounds existing in the reaction system, for example, aliphatic alcohols, aromatic monohydroxy compounds, alkylaryl carbonates, diaryl carbonates, dialkyl carbonates, and the like, and the reaction. Prior to this, the material may be heat treated with a raw material or a product.

When implementing this invention with the soluble catalyst melt | dissolved in a reaction system, it is preferable that these catalysts have high solubility to a reaction liquid in reaction conditions. Preferred catalysts in this sense include, for example, PbO, Pb (OH) ₂ , Pb (OPh) ₂ ; TiCl ₄ , Ti (OMe) ₄ , (MeO) Ti (OPh) ₃ , (MeO) ₂ Ti (OPh) ₂ , (MeO) ₃ Ti (OPh), Ti (OPh) ₄ ; SnCl ₄ , Sn (OPh) ₄ , Bu ₂ SnO, Bu ₂ Sn (OPh) ₂ ; FeCl _3, and the like will be treated with _{Fe (OH) 3, Fe (} OPh) 3 or the like, or combinations thereof, such as phenol or reaction mixture.

1 is a schematic diagram of a continuous multistage distillation column for carrying out the production method according to the present invention. Here, the continuous multistage distillation column 10 used in the present invention has a hard plate portion 5 above and below the cylindrical trunk portion 7 having a length L (cm) and an inner diameter D (cm), and the number n of stages therein. A gas outlet ₁ having an internal diameter d ₁ (cm) at the top of the tower or near the top thereof, having a structure having an internal 6 (6-1: filler, 6-2: tray) Liquid outlet ₂ having an inner diameter d ₂ (cm) at the bottom of the column or near the bottom thereof, at least one inlet 3 at the upper and / or middle portion of the tower below the gas outlet, the liquid It has one or more inlets 4 at the lower part of the tower as the upper part of the outlet, and in order to be able to stably produce at least one ton of diaryl carbonate per hour for not only distillation but also reaction simultaneously. It is necessary to satisfy the condition. In addition, since FIG. 1 is one Embodiment of the continuous multistage distillation column which concerns on this invention, arrangement | positioning of the internal 6 is not limited to the structure shown in FIG.

In the continuous multi-stage distillation column according to the present invention, not only the conditions from the simple distillation function but also the conditions necessary to advance the reaction at a stable and high selectivity are compounded, specifically,

(1) As length L (cm) satisfy | fills Formula (1),

      1500 ≤ L ≤ 8000 (1)

(2) As the inner diameter D (cm) of the tower satisfies the formula (2),

      100 ≤ D ≤ 2000 (2)

(3) The ratio between the length L (cm) and the inner diameter D (cm) of the tower satisfies the formula (3),

        2 ≤ L / D ≤ 40 (3)

(4) As the number n satisfies the formula (4),

       10 ≤ n ≤ 80 (4)

(5) The ratio between the inner diameter D (cm) of the tower and the inner diameter d ₁ (cm) of the gas outlet port satisfies the formula (5),

2 ≤ D / d ₁ ≤ 15 (5)

(6) The ratio between the inner diameter D (cm) of the tower and the inner diameter d ₂ (cm) of the liquid outlet port satisfies equation (6),

5 ≤ D / d ₂ ≤ 30 (6)

Should be

In addition, the term "top part or the upper part of a tower near it" used by this invention means the part which is up to about 0.25L from the top part downward, and the term "top part of a tower or lower part of the tower near it" is a tower bottom part. Up to about 0.25L upwards. In addition, "L" is synonymous with the above-mentioned definition.

By using a continuous multi-stage distillation column that satisfies the formulas (1), (2), (3), (4), (5) and (6) simultaneously, the aromatic carbonates containing diaryl carbonate as the main component In the preparation of the diaryl carbonate at a industrial scale of at least 1 ton per hour, at high selectivity and high productivity, for example, for a long time of at least 2000 hours, preferably at least 3000 hours, more preferably at least 5000 hours, It was found that it can be manufactured stably. It is not clear why the practice of the present invention allows the production of aromatic carbonates on an industrial scale with such excellent effects, but due to the combined effects caused when the conditions of formulas (1) to (6) are combined It is estimated. Moreover, the preferable range of each factor is shown below.

If L (cm) is smaller than 1500, since the reaction rate is lowered, the target production amount cannot be achieved, and in order to lower the equipment cost while securing the reaction rate that can achieve the desired production rate, L must be 8000 or less. More preferably, the range of L (cm) is 2000 ≦ L ≦ 6000, and more preferably 2500 ≦ L ≦ 5000.

If D (cm) is smaller than 100, the target amount of production cannot be achieved, and in order to lower the equipment cost while achieving the desired amount of production, D must be 2000 or less. The more preferable range of D (cm) is 150 ≦ D ≦ 1000, and more preferably 200 ≦ D ≦ 800.

When L / D is smaller than 2 or larger than 40, stable operation becomes difficult. Especially, when L / D is larger than 40, the pressure difference in the upper and lower parts of the tower becomes too large, so long-term stable operation becomes difficult and the temperature at the bottom of the tower must be increased. Therefore, side reactions tend to occur, leading to a decrease in selectivity. More preferably, the range of L / D is 3 ≦ L / D ≦ 30, and more preferably 5 ≦ L / D ≦ 15.

When n is less than 10, since the reaction rate falls, the target amount of production cannot be achieved, and in order to reduce the equipment cost while securing a reaction rate that can achieve the desired amount of production, n must be 80 or less. Moreover, when n is larger than 80, since the pressure difference in the upper and lower sides of a tower becomes too large, it becomes difficult not only for long-term stable operation but also to raise the temperature in a tower lower part, and a side reaction easily arises and it causes a fall of a selectivity. The range of more preferable n is 15 <= n <= 60, More preferably, it is 20 <= n <= 50.

When D / d ₁ is less than 2, not only the equipment cost is high, but also a large amount of gas components are easily released to the system, making stable operation difficult. When the D / d ₁ is larger than 15, the emission amount of gas components is relatively small, and stable operation becomes difficult. In addition, the reaction rate is lowered. The more preferable range of D / d ₁ is 2.5 ≦ D / d ₁ ≦ 12, and more preferably 3 ≦ D / d ₁ ≦ 10.

When D / d ₂ is less than 5, the equipment cost is high and the amount of liquid discharged is relatively high, making stable operation difficult. When the D / d ₂ is larger than 30, the flow rate of the liquid ejection or piping is rapidly accelerated to cause erosion. Leads to corrosion of the device. The more preferable range of D / d ₂ is 7 ≦ D / d ₂ ≦ 25, and more preferably 9 ≦ D / d ₂ ≦ 20.

Further, in the present invention if that d ₁ and the d ₂ satisfy the formula (7), it was found that it is more preferable.

1 ≤ d ₁ / d ₂ ≤ 6 (7)

Long-term stable operation as used in the present invention is 1000 hours or more, preferably 3000 hours or more, more preferably 5000 hours or more, there is no blockage or benefit of piping, and the operation can be continued in a normal state based on the operating conditions, It means that a predetermined amount of diaryl carbonate is produced while maintaining a high selectivity.

The present invention is characterized in that the diaryl carbonate is stably produced at a high selectivity for a long time with a high productivity of at least 1 ton per hour, but preferably at least 2 tons per hour, more preferably at least 3 tons per hour It is in producing carbonate. In addition, in the present invention, L, D, L / D, n, D / d ₁ and D / d ₂ of the continuous multi-stage distillation column are respectively 2000 ≤ L ≤ 6000, 150 ≤ D ≤ 1000, 3 ≤ L / D ≤ 30, 15 ≤ n ≤ 60, 2.5 ≤ D / d ₁ ≤ 12, 7 ≤ D / d ₂ ≤ 25, at least 2 tonnes per hour, preferably at least 2.5 tonnes per hour, more preferably 1 It is characterized by producing more than 3 tonnes of diaryl carbonate per hour. In addition, in the present invention, L, D, L / D, n, D / d ₁ , and D / d ₂ of the continuous multi-stage distillation column are respectively 2500 ≦ L ≦ 5000, 200 ≦ D ≦ 800, and 5 ≦ L / D. ≤ 15, 20 ≤ n ≤ 50, 3 ≤ D / d ₁ ≤ 10, 9 ≤ D / d ₂ ≤ 20, at least 3 tonnes per hour, preferably at least 3.5 tonnes per hour, more preferably 1 It is characterized by producing more than 4 tonnes of diaryl carbonate per hour.

The selectivity of the diaryl carbonate in the present invention refers to the alkylaryl carbonate reacted. In the present invention, the selectivity is usually 95% or higher, and preferably 97% or higher, more preferably 99% or higher. Can be.

The continuous multistage distillation column used in the present invention is preferably a distillation column having a tray and / or a packing as an internal. The term "internal" used in the present invention means a portion in which a distillation column actually comes into contact with gas and liquid. Such trays include, for example, bubble-cap trays, sieve trays, valve trays, counterflow trays, and superfrags. Superfrac tray, Maxfrac tray and the like are preferable, and as the filling material, Raschig ring, Lessing ring, Pall ring, Berl saddle, Pullout Irregular fillings such as Intalox saddle, Dixon packing, McMahon packing, Heli-Pak, Mela Pack, Gem Pack, Techno Pack, Flexi Pack, Sulzer Packing, Good Roll Packing, Regular fillers such as grit grids are preferred. A multi-stage distillation column that combines a tray portion and a filled portion of the packing may also be used. In addition, the term "number of stages n of internal" used in the present invention means the number of trays in the case of a tray, and the theoretical number of stages in the case of a filler. Therefore, in the case of a multi-stage distillation column having a tray section and a filled portion of the packing, n is the sum of the number of trays and the theoretical number of stages.

The reaction between the alkylaryl carbonate of the present invention and the aromatic monohydroxy compound present in the system has an extremely low equilibrium constant, a slow reaction rate, and an equalization reaction of the alkylaryl carbonate, which is the main reaction, as an equilibrium reaction. Small and slow reaction. As a continuous multi-stage distillation column for reaction distillation in which such a reaction of the present invention is carried out, it has been found that a multi-stage distillation column whose internal has both a packing material and a tray is preferable. And in this distillation column, it is preferable that the part filled with the packing material is provided in the upper part, and the tray part is provided in the lower part. Moreover, in this invention, it is more preferable that the filler is a regular filler, Furthermore, it is preferable that the regular filler is used 1 group or 2 groups or more. The regular filler is preferably at least one selected from melapack, gampack, technopack, flexipack, procedure packing, good roll packing, and grit grid.

In addition, in the continuous multi-stage distillation column of the present invention, it has been found that the perforated plate tray of the internal tray having the perforated plate portion and the downcomer portion is particularly excellent in terms of function and equipment cost. It has also been found that the porous plate tray preferably has 100 to 1000 holes per 1 m 2 of the porous plate portion. More preferable holes are 120-900 pieces per 1 m <2>, More preferably, they are 150-800 pieces. Moreover, it was also found that it is preferable that the cross-sectional area per hole of this perforated plate tray is 0.5-5 cm <2>. The cross-sectional area per one more preferable hole is 0.7-4 cm <2>, More preferably, it is 0.9-3 cm <2>. In addition, it was found that the perforated plate tray has 100 to 1000 holes per 1 m 2 of the perforated plate portion, and the cross-sectional area per hole is 0.5 to 5 cm 2, which is particularly preferable. And the regular filler is at least one selected from melapack, gumpack, technopack, flexipack, surgery packing, good roll packing, and grit grid, and the porous plate tray is 100 to 1 m2 of the perforated plate portion. It is also found that it is especially preferable in the case of the continuous multistage distillation column which has 1000 holes and whose cross-sectional area is 0.5-5 cm <2> per hole of the perforated plate tray. By adding the above conditions to a continuous multi-stage distillation column, it has been found that the problem of the present invention is more easily achieved.

When carrying out the present invention, a raw material containing an alkylaryl carbonate is continuously supplied into a continuous multi-stage distillation column in which a catalyst is present, and the reaction and distillation are simultaneously performed in the column to contain the produced dialkyl carbonate or alcohols. The low boiling point reaction mixture was continuously extracted from the top of the column into the gas phase, and the high boiling point reaction mixture containing aromatic carbonates containing the diaryl carbonate as the main reaction product was continuously extracted from the bottom of the column into the liquid phase. It is produced continuously. In this low boiling point reaction mixture, you may contain aromatic monohydroxy compounds, alkylaryl ethers, unreacted alkylaryl carbonate, etc. which exist in a system. Moreover, in this high boiling point reaction mixture, you may contain an aromatic monohydroxy compound, an unreacted alkylaryl carbonate, etc. Moreover, it is as above-mentioned that this raw material may contain dialkyl carbonate, alcohol, aromatic monohydroxy compound, diaryl carbonate, alkyl aryl ether, high boiling point reaction by-product etc. other than alkyl aryl carbonate. . In consideration of equipment, costs, and the like required for separation and purification in other processes, in the case of the present invention which is actually industrially carried out, it is preferable to contain a small amount of these compounds.

Moreover, in this invention, it is also a preferable method to perform the reflux operation which condenses the gas discharge component of the tower top of a reaction distillation column, and returns a part to the upper part of a distillation column. In this case, the reflux ratio is in the range of 0.01-10, preferably 0.08-5, more preferably 0.1-2. In the present invention, in order to continuously supply the raw material containing the alkylaryl carbonate into the continuous multi-stage distillation column, from one or several inlets provided below the gas outlet at the top of the distillation column but installed at the upper or middle portion of the column, Preference is given to supplying in the liquid and / or gas phase. In addition, in the case of using a distillation column having a packing part in the upper part and a tray part in the lower part, which is a preferred embodiment of the present invention, at least one place of the inlet is preferably installed between the packing part and the tray part. Moreover, when a filling consists of two or more regular fillings, it is also a preferable method to provide an inlet in the space which comprises these several fillings.

In the present invention, any method of presenting the catalyst in the continuous multi-stage distillation column may be used. However, in the case of a solid phase in which the catalyst is insoluble in the reaction liquid, the catalyst may be provided in the form of a packing in the stage of the continuous multi-stage distillation column. And a method of fixing in the tower. In addition, in the case of the catalyst which melt | dissolves in a raw material or a reaction liquid, it is preferable to supply in a distillation column from a position higher than the middle part of a distillation column. In this case, the catalyst liquid dissolved in the raw material or the reaction liquid may be introduced together with the raw material, or the catalyst liquid may be introduced from an introduction port separate from the raw material. The amount of the catalyst used in the present invention also varies depending on the type of catalyst used, the type of raw material and the ratio thereof, the reaction conditions such as the reaction temperature and the reaction pressure, but is expressed as a ratio with respect to the total mass of the raw material, and usually 0.0001 It is used at -30 mass%, Preferably it is 0.005-10 mass%, More preferably, it is 0.001-1 mass%.

The reaction time of the transesterification reaction carried out in the present invention is considered to correspond to the average residence time of the reaction liquid in the continuous multi-stage distillation column, but this is the shape and number of stages of the internals of the distillation column, the amount of raw materials supplied, the type and amount of the catalyst, It depends on reaction conditions etc., and is 0.01 to 10 hours normally, Preferably it is 0.05 to 5 hours, More preferably, it is 0.1 to 3 hours.

Although reaction temperature changes with the kind of raw material compound to be used, and the kind and quantity of a catalyst, it is 100-350 degreeC normally. In order to increase the reaction rate, it is preferable to increase the reaction temperature. However, when the reaction temperature is high, side reactions are liable to occur. For example, by-products such as Fries rearrangement products of alkylaryl ethers or diaryl carbonates and ester compounds thereof This is undesirable because it increases. In this sense, the preferred reaction temperature is in the range of 130 to 280 ° C, more preferably 150 to 260 ° C, still more preferably 180 to 240 ° C. Although the reaction pressure varies depending on the type, composition, and reaction temperature of the raw material compound to be used, it may be any state of reduced pressure, atmospheric pressure, or pressurization, and the top pressure is usually 0.1 to 2 × 10 ⁷ Pa, preferably 10 ³ to 10 ⁶ Pa, and more preferably it is carried out in the range of ⁵ × 10 ³ ~10 5 Pa.

The material constituting the continuous multi-stage distillation column used in the present invention is mainly metal materials such as carbon steel and stainless steel, but stainless steel is preferred in view of the quality of the diaryl carbonate to be produced.

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

Halogen content was measured by the ion chromatography method.

Example 1

<Continuous multi-stage distillation column>

A continuous multi-stage distillation column with L = 3100 cm, D = 500 cm, L / D = 6.2, n = 30, D / d ₁ = 3.85, D / d ₂ = 11.1 as shown in FIG. 1 was used. In this embodiment, two Melapacks (11 total theoretical stages) are provided at the upper side as an internal, and have a cross-sectional area of about 1.3 cm ² and a hole number of about 250 holes / m ² per hole at the bottom. A perforated plate tray was used.

<Reactive distillation>

The mixture containing 18 mass% of methylphenyl carbonates obtained by transesterifying the mixture which consists of dimethyl carbonate / phenol = 1.3 (mass ratio) was used as a raw material. In this raw material, 26 mass% of dimethyl carbonates, 6 mass% of anisoles, 48 mass% of phenols, and 1 mass% of diphenyl carbonates were contained, and about 100 ppm of catalysts were contained as Pb (OPh) ₂ . This raw material was substantially free of halogen (out of the limit of detection in ion chromatography and 1 ppb or less).

From the raw material introduction port provided between a melapak and a porous plate tray, this raw material was introduce | transduced into the said continuous multistage distillation column at the flow rate of 66 ton / hr. Reaction distillation was performed continuously on the conditions of the tower bottom temperature of 210 degreeC, the tower top pressure of 3x10 <^4> Pa, and reflux ratio 0.3. After 24 hours, stable normal operation was achieved. The liquid continuously discharged from the column bottom contained 38.4 mass% of methylphenyl carbonate and 55.6 mass% of diphenyl carbonate. It can be seen that the yield of diphenyl carbonate from methylphenyl carbonate is 5.13 tons per hour. The selectivity of diphenyl carbonate was 99% with respect to the reacted methylphenyl carbonate.

Long-term continuous operation was performed under this condition. After 500 hours, after 2000 hours, after 4000 hours, after 5000 hours, and after 6000 hours, the amount of diphenyl carbonate produced (excluding diphenyl carbonate contained in the raw materials) is 5.13 tons, 5.13 tons, 5.14 tons, and 5.14 per hour. It was 5.13 tons, and the selectivity was very stable, 99%, 99%, 99%, 99%, 99%. In addition, the produced aromatic carbonate was substantially free of halogen (1 ppb or less).

Example 2

Reaction distillation was performed on condition of the following using the continuous multistage distillation column similar to Example 1.

<Reactive distillation>

The mixture containing 21 mass% of methylphenyl carbonates obtained by transesterifying the mixture which consists of dimethyl carbonate / phenol = 1.9 (mass ratio) was used as a raw material. In this raw material, 32 mass% of dimethyl carbonate, 5 mass% of anisole, 41 mass% of phenols, and 1 mass% of diphenyl carbonates were contained, and about 250 ppm of Pb (OPh) ₂ was further contained. This raw material was substantially free of halogen (out of the limit of detection in ion chromatography and 1 ppb or less).

From the raw material introduction port provided between a melapack and a porous plate tray, this raw material was introduce | transduced into the said continuous multistage distillation column at the flow volume of 80 ton / hr. Reaction distillation was performed continuously on the conditions of the tower bottom temperature of 205 degreeC, the tower top pressure of 2x10 <^4> Pa, and reflux ratio of 0.5. After 24 hours, stable normal operation was achieved. The liquid continuously discharged from the column bottom contained 36.2 mass% of methylphenyl carbonate and 60.8 mass% of diphenyl carbonate. It was found that the yield of diphenyl carbonate from methylphenyl carbonate was 8.06 ton per hour. The selectivity of diphenyl carbonate was 99% with respect to the reacted methylphenyl carbonate.

Long-term continuous operation was performed under this condition. After 500 hours, after 1000 hours, after 1500 hours, after 2000 hours, and after 2500 hours, the amount of diphenyl carbonate produced (excluding diphenyl carbonate contained in the raw material) is 8.06 ton, 8.07 ton, 8.07 ton per hour, It was 8.06 ton and 8.07 ton and the selectivity was very stable at 99%, 99%, 99%, 99%, 99%. In addition, the produced aromatic carbonate was substantially free of halogen (1 ppb or less).

Example 3

Reaction distillation was performed on condition of the following using the continuous multistage distillation column similar to Example 1 except having made cross section area per hole of a porous plate tray into about 1.8 cm <2>.

<Reactive distillation>

The mixture containing 16 mass% of methylphenyl carbonates obtained by transesterifying the mixture which consists of dimethyl carbonate / phenol = 1.4 (mass ratio) was used as a raw material. In this raw material, 27 mass% of dimethyl carbonate, 7 mass% of anisole, 49 mass% of phenols, and 0.5 mass% of diphenyl carbonates were contained, and about 200 ppm of catalysts were contained as Pb (OPh) ₂ . This raw material was substantially free of halogen (out of the limit of detection in ion chromatography and 1 ppb or less).

From the raw material introduction port provided between a melapack and a porous plate tray, this raw material was introduce | transduced into the said continuous multistage distillation column at the flow volume of 94 ton / hr. Reaction distillation was performed continuously on the conditions of the tower | column bottom part temperature of 215 degreeC, the tower top pressure of 2.5x10 <^4> Pa, and reflux ratio 0.4. After 24 hours, stable normal operation was achieved. The liquid continuously discharged from the column bottom contained 35.5% by mass of methylphenyl carbonate and 59.5% by mass of diphenyl carbonate. The yield of diphenyl carbonate from methylphenyl carbonate was found to be 7.28 tons per hour. The selectivity of diphenyl carbonate was 99% with respect to the reacted methylphenyl carbonate.

Long-term continuous operation was performed under this condition. After 500 hours, after 1000 hours, after 1500 hours, after 2000 hours, and after 2500 hours, the amount of diphenyl carbonate produced (excluding diphenyl carbonate contained in the raw material) is 7.28 tons, 7.28 tons, 7.29 tons, 7.29 per hour. Ton, 7.28 tons, selectivity was very stable, 99%, 99%, 99%, 99%, 99%. In addition, the produced aromatic carbonate was substantially free of halogen (1 ppb or less).

The alkylaryl carbonate obtained by the transesterification reaction of dialkyl carbonate and an aromatic monohydroxy compound is used as a raw material, and this raw material is continuously supplied to the continuous multistage distillation column in which a catalyst exists using a continuous multistage distillation column, and a diaryl carbonate is obtained. In the continuous production of aromatic carbonates as the main product, it is very suitable as a specific method capable of stably producing a diaryl carbonate for a long time with high selectivity and high productivity on an industrial scale of 1 ton or more per hour.

1 is a schematic diagram of a continuous multi-stage distillation column embodying the present invention. An internal 6 is provided inside the body part. In addition, description of the code | symbol used in FIG. 1 is as follows;

1: gas outlet, 2: liquid outlet, 3: inlet, 4: inlet, 5: light plate, 6-1: internal (fill), 6-2: internal (tray), 7: body portion, 10: continuous multi-stage distillation column, L: length of trunk portion (㎝), d: inner diameter of the trunk portion (㎝), d _1: gas outlet to the inner diameter (㎝), d _2: inner diameter of the liquid to the outlet (㎝).

Claims (19)

As a manufacturing method of aromatic carbonates which use as a raw material the alkylaryl carbonate obtained by the transesterification reaction of a dialkyl carbonate and an aromatic monohydroxy compound as a raw material, (i) continuously feeding the raw materials into a continuous multi-stage distillation column in which a catalyst is present; (ii) reacting the raw materials to produce a dialkyl carbonate and a diaryl carbonate, (iii) continuously extracting the low boiling reaction mixture containing the resulting dialkyl carbonate from the top of the column into the gas phase and continuously extracting the high boiling reaction mixture containing the diaryl carbonate from the bottom of the column into the liquid phase; , (a) The raw material continuously supplied into the continuous multistage distillation column contains 5 to 38 mass% of the dialkyl carbonate and 5 to 61 mass% of the aromatic monohydroxy compound, based on the mass of the raw material, (b) The continuous multi-stage distillation column has a structure having a hard plate portion above and below a cylindrical trunk portion having a length L (cm) and an inner diameter D (cm), and having an internal having a number n inside thereof, Gas outlet of inner diameter d ₁ (cm) at the top of the near tower, liquid outlet of inner diameter d ₂ (cm) at the bottom of the tower or the bottom of the tower close thereto, upper and / or middle of the tower as lower than the gas outlet Having at least one inlet in the part, and at least one inlet in the lower part of the tower as upper part of the liquid outlet, (1) Length L (cm) satisfy | fills Formula (1),       1500 ≤ L ≤ 8000 (1) (2) The inner diameter D (cm) of the tower satisfies the formula (2),       100 ≤ D ≤ 2000 (2) (3) The ratio between the length L (cm) and the inner diameter D (cm) of the tower satisfies the formula (3),         2 ≤ L / D ≤ 40 (3) (4) The singular n satisfies the expression (4),        10 ≤ n ≤ 80 (4) (5) The ratio between the inner diameter D (cm) of the tower and the inner diameter d ₁ (cm) of the gas outlet port satisfies the formula (5), 2 ≤ D / d ₁ ≤ 15 (5) (6) the ratio between the inner diameter D (cm) of the tower and the inner diameter d ₂ (cm) of the liquid outlet port satisfies the formula (6), 5 ≤ D / d ₂ ≤ 30 (6) Method characterized by that. The method of claim 1, The distillation is also carried out simultaneously in the step (ii). The method according to claim 1 or 2, Aromatic carbonates containing diaryl carbonate as a main product are continuously produced, and the production amount of the diaryl carbonate is 1 ton or more per hour. Alkyl aryl carbonate obtained by transesterification of dialkyl carbonate and aromatic monohydroxy compound is used as a raw material, and this raw material is continuously supplied into a continuous multistage distillation column in which a catalyst is present, and reaction and distillation are simultaneously performed in the column. By the reaction distillation method, the low boiling point reaction mixture containing the produced dialkyl carbonate is continuously extracted from the top of the column into the gas phase, and the high boiling point reaction mixture containing the diaryl carbonate is continuously extracted from the bottom of the column into the liquid phase. In continuously producing aromatic carbonates containing diaryl carbonate as the main product, (a) The raw material continuously supplied into the continuous multistage distillation column contains 5-38 mass% of the dialkyl carbonate and 5-61 mass% of the aromatic monohydroxy compound, based on the mass of the raw material, (b) The continuous multi-stage distillation column has a structure having a hard plate portion above and below a cylindrical trunk portion having a length L (cm) and an inner diameter D (cm), and having an internal having a number n in the top, or A gas outlet of inner diameter d ₁ (cm) at the top of the tower close to it, a liquid outlet of inner diameter d ₂ (cm) at the bottom of the tower or a bottom of the tower close to it, an upper portion of the tower as lower than the gas outlet Having at least one inlet in the middle, and at least one inlet at the bottom of the tower as upper part of the liquid outlet, (1) Length L (cm) satisfy | fills Formula (1),       1500 ≤ L ≤ 8000 (1) (2) The inner diameter D (cm) of the tower satisfies the formula (2),       100 ≤ D ≤ 2000 (2) (3) The ratio between the length L (cm) and the inner diameter D (cm) of the tower satisfies the formula (3),         2 ≤ L / D ≤ 40 (3) (4) The singular n satisfies the expression (4),        10 ≤ n ≤ 80 (4) (5) The ratio between the inner diameter D (cm) of the tower and the inner diameter d ₁ (cm) of the gas outlet port satisfies the formula (5), 2 ≤ D / d ₁ ≤ 15 (5) (6) the ratio between the inner diameter D (cm) of the tower and the inner diameter d ₂ (cm) of the liquid outlet port satisfies the formula (6), 5 ≤ D / d ₂ ≤ 30 (6) Industrial production method of aromatic carbonates whose main product is a diaryl carbonate characterized by the above-mentioned. The method of claim 4, wherein Process for producing a diaryl carbonate is more than 1 ton per hour. The method according to any one of claims 1, 2, 4 or 5, The raw material further contains 0.5-15 mass% alkylaryl ether with respect to the mass of the raw material. The method according to any one of claims 1, 2, 4 or 5, The d ₁ and the d ₂ are given by equation (7), 1 ≤ d ₁ / d ₂ ≤ 6 (7) Method characterized by being satisfied. The method according to any one of claims 1, 2, 4 or 5, L, D, L / D, n, D / d ₁ and D / d ₂ of the continuous multi-stage distillation column are 2000 ≤ L ≤ 6000, 150 ≤ D ≤ 1000, 3 ≤ L / D ≤ 30, 15 ≤ n ≤ 60, 2.5 ≤ D / d ₁ ≤ 12, 7 ≤ D / d ₂ ≤ 25. The method according to any one of claims 1, 2, 4 or 5, L, D, L / D, n, D / d ₁ and D / d ₂ of the continuous multi-stage distillation column are 2500 ≤ L ≤ 5000, 200 ≤ D ≤ 800, 5 ≤ L / D ≤ 15, 20 ≤ n ≤ 50, 3 ≤ D / d ₁ ≤ 10, 9 ≤ D / d ₂ ≤ 20. The method according to any one of claims 1, 2, 4 or 5, The continuous multistage distillation column is a distillation column having a packing and a tray as its internals. The method of claim 10, The continuous multi-stage distillation column is a distillation column having a charge at the top and a tray at the bottom thereof as the internals. The method of claim 10, Wherein the filler of the internal is a regular filler. The method of claim 10, The tray of the internal is a perforated plate tray having a perforated plate portion and a downcomer portion. The method of claim 10, The filling of the internal is one or two or more regular fillings, and the tray is a perforated plate tray having a perforated plate portion and a downcomer portion. The method of claim 12, The rule fillings are Melapak, Gempak, TECHNO-PAK, FLEXI-PAK, a Sulzer packing, a Goodroll packing, Gritgrid (Glitchgrid) at least one selected from. The method of claim 13, The porous plate tray has 100 to 1000 holes per square meter of area of the porous plate portion. The method of claim 13, A cross-sectional area per hole in the perforated plate tray is 0.5 to 5 cm 2. The method of claim 14, The regular filling is at least one selected from Melapack, Gampack, Technopack, Flexipack, Sulzer Packing, Good Roll Packing, and Grit Grid, and the perforated plate tray is made of 100 to 1000 holes per square meter of the perforated plate area. The cross-sectional area per hole of the perforated plate tray is 0.5-5 cm <2>. delete

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