JP2000005503A - Method and device for reaction distillation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reaction distillation method by which the efficiency of the reaction is further improved and to provide the reaction distillation device appropriate for the method. SOLUTION: The reaction distillation device having 3 plates and with a heater for heating a liq. reactant provided to at least one plate A among the reaction plates except the bottom plate and the plate supplied with the feed is used to bring about an equilibrium reaction while heating the reactant on the plate A. Consequently, the temp. gradient in the distiller is further reduced as shown in the figure to uniformize the temp. in the distillation device, and the temp. of the whole region in the distillation device is further raised without increasing the heat supplied from the heater such as a reboiler furnished at the bottom. Accordingly, the rate of the equilibrium reaction is further increased, the efficiency of the equilibrium reaction is improved, and the formation of by-product is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactive distillation apparatus and a reactive distillation method applicable to an equilibrium reaction. More specifically, the present invention provides, for example,
Various equilibrium reactions such as transesterification between an aromatic hydroxy compound and an aliphatic carboxylic acid ester, or transesterification between an aromatic carboxylic acid ester and an aliphatic carbonate and / or an aliphatic / aromatic carbonate. The present invention relates to a reactive distillation apparatus and a reactive distillation method applicable to the present invention.

[0002]

2. Description of the Related Art Conventionally, when the equilibrium of an equilibrium reaction is disadvantageous to the production system side, the above-mentioned equilibrium is favorably applied to the production system side to increase the reaction efficiency (equilibrium conversion) by performing reactive distillation. That is being done. For example, "Chemical Engineering" 5th
Vol. 7, No. 1, pp. 77-79 (1993) describes the above-mentioned reactive distillation with specific examples.

[0003] In general, reactive distillation is carried out by using a distillation column such as a continuous multistage distillation column (reactive distillation apparatus). When the reactive distillation is performed in the distillation column, with the progress of the reaction, the higher boiling components contained in the reaction solution are distributed more in the lower stage of the distillation column,
Components having a lower boiling point are distributed more in the upper stage of the distillation column. Therefore, in the distillation column, the temperature (liquid temperature) in the column decreases from the bottom to the top.

[0004] The reaction rate of the equilibrium reaction decreases as the temperature decreases. For this reason, when performing reactive distillation in the distillation column, from the bottom toward the top,
The reaction speed becomes slow. That is, when the reactive distillation is performed in the distillation column, the reaction efficiency of the equilibrium reaction decreases from the bottom to the top.

[0005] Therefore, in order to further improve the reaction efficiency, that is, to increase the reaction rate, the temperature in the column is further increased. Specifically, by increasing the amount of heat supplied from a bottom heating device such as a reboiler provided at the bottom of the distillation column, the temperature in the column is increased.

[0006]

However, in order to further raise the temperature inside the column, if the reboiler provided at the bottom of the distillation column is used for heating, the temperature inside the column gradually rises from the lower stage. Therefore, a large amount of heat is required to raise the temperature of the entire area inside the distillation column. That is, in order to increase the reaction rate by increasing the amount of heat supplied from the reboiler, the amount of heat must be significantly increased.

[0007] When the amount of heat supplied from the reboiler is increased, the amount of steam rising in the column increases, so that the reflux ratio of the distillation column must be increased. However,
When the reflux ratio is increased, the upper side of the distillation column is cooled by the reflux liquid, so that the temperature of the upper side (liquid temperature)
Does not rise sufficiently. In addition, when the amount of heat supplied from the reboiler is increased, the reaction liquid in the lower stage of the distillation column is overheated, so that a side reaction is promoted and a by-product is easily generated. For this reason, it is difficult to heat the lower stage of the distillation column to a certain temperature or higher.

That is, in the above-mentioned conventional reactive distillation method, a large amount of heat is required, and it is difficult to sufficiently raise the temperature in the entire distillation column, and it is easy to generate by-products. Therefore, the conventional reactive distillation method has a problem that it is difficult to improve the reaction efficiency of the equilibrium reaction.

Therefore, there is a demand for a reactive distillation method that can sufficiently raise the temperature of the entire area inside the distillation column without applying a large amount of heat and that hardly generates by-products. That is, a reactive distillation method capable of further improving the reaction efficiency of the equilibrium reaction by increasing the reaction rate of the equilibrium reaction as compared with the conventional one, and a reactive distillation method suitable for performing the method. A device is desired.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a reactive distillation method capable of further improving the reaction efficiency of an equilibrium reaction, and a method for performing the method. An object of the present invention is to provide a suitable reactive distillation apparatus.

[0011]

Means for Solving the Problems The present inventors have intensively studied a reactive distillation apparatus and a reactive distillation method in order to solve the above conventional problems. As a result, a reaction device in which the number of stages is three or more and at least one stage (A) of the reaction stages excluding the column bottom and the supply stage for supplying the raw material is provided with a heating device for heating the reaction solution. Increasing the amount of heat supplied from a bottom heating device such as a reboiler provided at the bottom of the column by performing an equilibrium reaction while heating the reaction solution present in the stage (A) using a distillation device. It was found that the temperature of the entire region inside the reactive distillation apparatus could be further increased. By adopting the reactive distillation method, the reaction efficiency of the equilibrium reaction can be further improved by increasing the reaction rate of the equilibrium reaction, and the generation of by-products can be suppressed. They have found what they can do and have completed the present invention.

That is, the reactive distillation apparatus of the present invention has three stages for performing an equilibrium reaction in order to solve the above-mentioned problems.
At least one stage (A) of the reaction stages excluding the column bottom and the supply stage for supplying the raw material is provided with a heating system for heating the reaction liquid. It is characterized by.

And, in the reactive distillation apparatus of the present invention,
For example, the heating device is provided inside the stage (A) so as to internally heat the reaction solution existing in the stage (A).
Alternatively, in the reactive distillation apparatus of the present invention, for example, the heating device is provided outside the stage (A) so as to externally heat the reaction solution existing in the stage (A). Or, in the reactive distillation apparatus of the present invention, for example, the heating apparatus,
The reaction solution extracted from the stage (A) is provided outside the reaction stage so as to be heated and returned to the reaction stage. further,
In the reactive distillation apparatus of the present invention, for example, the heated reaction liquid is returned to the above stage (A).

In order to solve the above-mentioned problems, the reactive distillation method of the present invention is a reactive distillation method which is performed using a reactive distillation apparatus having three or more stages, wherein It is characterized in that an equilibrium reaction is performed while heating the reaction solution present in at least one of the reaction stages (A) excluding the stages.

And, in the reactive distillation method of the present invention,
For example, the above equilibrium reaction is a transesterification reaction between an aromatic hydroxy compound and an aliphatic carboxylic acid ester, a transesterification reaction between an aromatic carboxylic acid ester and an aliphatic carbonic acid ester, and an aromatic carboxylic acid ester and an aliphatic carboxylic acid ester.
At least one transesterification reaction selected from the group consisting of transesterification reactions with aromatic carbonates.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A reactive distillation apparatus according to the present invention comprises:
A reactive distillation apparatus having three or more stages for performing an equilibrium reaction, wherein the reaction solution is added to at least one stage (A) of the reaction stages excluding a column bottom and a supply stage for supplying a raw material. In this configuration, a heating device for heating is provided. Further, the reactive distillation method according to the present invention is a reactive distillation method performed using a reactive distillation apparatus having three or more stages, wherein the stage (A) is used.
This is a method of performing an equilibrium reaction while heating the reaction solution existing in the reaction.

The reactive distillation apparatus and the reactive distillation method according to the present invention can be used for a one-step equilibrium reaction (simple equilibrium reaction) or a sequential complex reaction in which the equilibrium reactions are combined in two steps. The present invention can be applied to a complicated sequential complex reaction in which three or more reactions are combined.

The above-mentioned equilibrium reaction is more preferably an endothermic reaction. When the equilibrium reaction is an endothermic reaction, by raising the temperature (reaction temperature) in the reactive distillation apparatus, the reaction rate becomes faster, and the equilibrium of the equilibrium reaction becomes more advantageous to the production system side. (Equilibrium conversion). That is, the reactive distillation apparatus and the reactive distillation method according to the present invention, when the equilibrium reaction is an endothermic reaction,
It exerts an even greater effect.

The reactive distillation apparatus has three or more stages,
More preferably, the structure has four or more stages, and still more preferably five or more stages, as long as the structure can perform an equilibrium reaction.
That is, the reactive distillation apparatus has a gas phase in the apparatus,
Any structure may be used as long as the generated low-boiling component can be continuously separated and removed from the gas phase, that is, a structure that can perform so-called reactive distillation. As the reactive distillation apparatus, a continuous multistage distillation column is suitable.

As the continuous multistage distillation column, a distillation column having three or more stages excluding the top (top) and the bottom (bottom) is preferable. Such distillation columns include, for example, packed columns filled with packing materials such as Raschig rings, pole rings, interlock saddles, Dickson packings, McMahon packings, sludge packings; trays such as bubble bell trays, sieve trays, valve trays and the like. A commonly used distillation column such as a tray column using a (tray plate) can be employed. Further, a combined distillation column having both a tray and a packed bed can be employed. The above-mentioned number of plates indicates the number of plates in a plate column, and indicates the number of theoretical plates in a packed column.

In the reactive distillation apparatus according to the present invention, a heating device for heating the reaction solution is provided in at least one stage (A) of the reaction stages excluding the column bottom and the supply stage for supplying the raw materials. I have. The above stage (A) may be any stage of the reaction stage, but is preferably lower than the supply stage located at the uppermost stage. The above-mentioned reaction stage refers to a region where the raw material is present (reaction portion), particularly, a region where the catalyst is present (reaction portion) in an equilibrium reaction using a catalyst. In addition, the bottom of the reactive distillation apparatus according to the present invention is provided with a tower bottom heating device such as a reboiler, similarly to the conventional reactive distillation apparatus. Further, the reactive distillation apparatus according to the present invention is provided with a raw material heating device for preheating the raw material as necessary.

The above-mentioned heating device may be provided so as to be able to heat the reaction solution present in the stage (A). Specifically, the heating device may be provided inside the stage (A) so as to internally heat the reaction solution existing in the stage (A), and may be provided inside the stage (A). May be provided outside the above stage (A) in order to externally heat the reaction solution, or provided outside the reaction stage so that the reaction solution extracted from the stage (A) is heated and returned to the reaction stage. You may. When the reaction solution extracted from the stage (A) is heated and returned to the reaction stage, the reaction solution may be returned to the extracted stage (A), and may be returned to the stage (A). It may be returned to the upper stage or may be returned to the lower stage than the stage (A). However, in order to further improve the reaction efficiency, it is preferable to return to the extracted stage (A).

The number of heating devices is not particularly limited. In addition, one heating device may be configured to heat the reaction solution present in one stage (A), or may be configured to heat the reaction solution existing in a plurality of stages (A) (a plurality of reaction solutions may be used). (A configuration in which heating is performed across the step (A)). However, as the number of heating devices increases, the equipment cost increases, the structure of the reactive distillation device becomes complicated, and the effect obtained per heating device decreases (the installation efficiency decreases). For this reason, the heating device is used for about 20% of the reaction stage, more preferably 1%.
It is desirable that the reaction solution is provided so as to be able to heat the reaction solution existing at about 0%, more preferably about 5%. More specifically, it is desirable to keep the number of heating devices to two or less.

Examples of a heating device suitable for heating the reaction solution internally or externally include various heaters. When the internal heating is performed, the heater is built in the reactive distillation apparatus. On the other hand, in the case of external heating, the heater is wound around a reactive distillation apparatus, for example. As a heating device suitable for heating the extracted reaction solution, for example, a reboiler or the like can be given. The configuration of the heater or reboiler, that is, the configuration of the heating device is not particularly limited.

As described above, it is preferable that the heating device be provided in the stage (A) located below the uppermost supply stage (hereinafter referred to as the upper supply stage). The optimal stage (A) in which a heating device should be provided in the reaction stage is the reaction type of the reactive distillation device, the number and position of the supply stages, the composition and supply method of the raw materials, the temperature and temperature in the reactive distillation device to be maintained. What is necessary is just to determine in consideration of various conditions, such as a gradient. The amount of heat to be supplied by the heating device and the type of the heating device may be determined in consideration of these various conditions. By providing the heating device in the optimal stage (A), the temperature gradient in the reactive distillation device can be made smaller and the temperature in the device can be made more uniform, and the reboiler provided in the bottom of the column can be obtained. Without increasing the amount of heat supplied from the reactor, the temperature of the entire region inside the reactive distillation apparatus can be further increased.

Specifically, the heating device is provided between the lower stage of about 10% of the reaction stage as viewed from the upper supply stage and the upper stage of about 10% of the reaction stage as viewed from the bottom of the column. More preferably, it is provided in a stage between about 20% of the reaction stages from the lower side as viewed from the upper feed stage and about 20% of the reaction stages as viewed from the bottom of the column. Is more preferred.

By providing the heating device in the optimal stage (A), the temperature inside the reactor in the reactor can be increased as compared with the conventional one without increasing the temperature at the bottom of the column as shown in FIG. 1, for example. Can be done.

For example, a reactive distillation apparatus is provided with a plurality of supply stages, and a lower supply stage (a supply stage located on the lower side).
In the case where the raw material is supplied in a gaseous or gas-liquid mixed state from above, the heating device is provided in an upper stage from the lower supply stage. Since the gas-liquid flow rate that goes up and down in the device is higher on the upper side than on the lower supply stage, the temperature on the upper side can be raised more efficiently than on the lower supply stage. On the other hand, if a heating device is provided in the lower stage adjacent to the supply stage located on the uppermost side,
There is a possibility that the temperature of the entire region within the reactive distillation apparatus may not be efficiently increased, and the temperature of the concentrating unit may be unnecessarily increased, so that the product may not be efficiently separated.

Next, the reactive distillation apparatus and the reactive distillation method according to the present invention will be described in more detail. In the following description, for the sake of convenience, the raw material (A) and the raw material (B) are used, and a one-stage process represented by the following formula: raw material (A) + raw material (B) ⇔ product (C) + product (D) An example in which an equilibrium reaction (simple equilibrium reaction) is performed to obtain a target product (C) will be described. However, the order of the boiling points of the raw material (A) and the raw material (B) is as follows: the raw material (A)> the raw material (B), and the order of the boiling points of the product (C) and the product (D) is the product ( Let C)> product (D).

As shown in FIG. 2, a reactive distillation apparatus (hereinafter, simply referred to as a reactive distillation column) 1 according to the present embodiment includes:
Reboiler 2, condenser 3, which is a bottom heating device, and
A pump 4 and the like are provided.

The reactive distillation column 1 has three or more stages,
The raw material (A) and the raw material (B) are brought into gas-liquid contact. Raw material supply pipes 5 and 6 are connected to the reactive distillation column 1. Also,
The bottom of the reactive distillation column 1 is connected to the reboiler 2 via an extraction pipe 7 and a conduit 13. Further, the top of the reactive distillation column 1 is connected to the condenser 3 via a conduit 11. The raw material supply pipes 5 and 6 are connected to the reactive distillation column 1
Are sequentially connected to different stages (supply stages) from the top of the column. That is, in the reactive distillation column 1, the raw material supply pipe 6 is connected to a lower stage than the raw material supply pipe 5. It is more preferable that the raw material supply pipe 6 is connected to the bottom of the column (lowest stage) in order to further improve the reaction efficiency.

The raw material supply pipe 5 continuously supplies the raw material (A) to the reactive distillation column 1. The raw material supply pipe 6 continuously supplies the raw material (B) to the reactive distillation column 1. By supplying the raw material (A) having a higher boiling point to the upper stage side in the reactive distillation column 1, the raw material (A) and the raw material (B) can be brought into sufficient contact. In addition, the raw material (A)
The mixture of (B) may be continuously supplied to the reactive distillation column 1. In this case, the raw material supply pipe 6 can be omitted.

The reactive distillation column 1 has two stages (a plurality of stages) between a stage to which the raw material supply pipe 5 is connected and a stage to which the raw material supply tube 6 is connected. A)
(Not shown) are provided with internal heaters (heating devices) 14 and 15 for internally heating the reaction solution. Internal heater 14.1
5 is to reduce the temperature gradient in the reactive distillation column 1 by heating the reaction solution, make the temperature in the reactive distillation column 1 more uniform, and increase the amount of heat supplied from the reboiler 2 Without this, the temperature in the entire area of the reactive distillation column 1 is further increased.

The reboiler 2 is connected to the bottom of the reactive distillation column 1 via an extraction pipe 7 and a conduit 13. The reboiler 2 heats the bottom liquid extracted through the extraction pipe 7 and returns the liquid to the bottom through the conduit 13. That is, the reboiler 2 heats and circulates the bottom liquid. The extraction pipe 7 is branched so that a part of the bottom liquid can be continuously extracted as a bottom liquid outside the reaction system.

The condenser 3 condenses and liquefies the distillate from the reactive distillation column 1. The condenser 3 is connected to the top of the reactive distillation column 1 via a conduit 11 and connected to the pump 4 via an extraction pipe 8. The condenser 3 is provided with an adjusting pipe 9 having a pressure adjusting valve 10. The extraction pipe 8 is branched so that a part of the distillate can be continuously extracted outside the reaction system.

The pump 4 recirculates the distillate to the reactive distillation column 1 at a predetermined reflux ratio. Pump 4
It is connected to the condenser 3 via the extraction pipe 8 and to the top of the reactive distillation column 1 via the conduit 12.

Next, an example of a method for producing the product (C) using the reactive distillation apparatus having the above configuration will be described. First,
The raw material (A) is continuously supplied to the reactive distillation column 1 via the raw material supply pipe 5 and the raw material (B) is supplied to the reactive distillation column 1 via the raw material supply pipe 6. These raw materials (A) and (B) may be supplied in a liquid state, may be supplied in a gaseous state, or may be supplied in a gas-liquid mixed state. In addition, the raw material (A) may include a part of the raw material (B), and the raw material (B) may include a part of the raw material (A).

Then, the raw material (A) and the raw material (B) supplied to the reactive distillation column 1 are subjected to gas-liquid contact, that is, reactive distillation. Then, while the bottom liquid is heated by the reboiler 2, the reaction liquid present in the two stages (A) is internally heated by the internal heaters 14 and 15, whereby the reactive distillation column 1 is heated.
The temperature gradient inside the reactive distillation column 1 is made more uniform by making the temperature gradient inside the reactive distillation column 1 smaller, and the temperature in the entire area inside the reactive distillation column 1 is further raised.

Thus, the equilibrium reaction proceeds efficiently,
A product (C) and a product (D) are formed and both are separated. The product (C) flows down in the reactive distillation column 1 and is continuously drawn out of the reaction system as a bottom liquid (column bottom liquid). That is, the product (C) is continuously taken out of the reaction system as a bottom liquid. The product (D) as a by-product rises in the reactive distillation column 1 and is continuously extracted as a distillate. By performing the above reaction operation, the product (C) can be efficiently and continuously produced.

Further, when, for example, a homogeneous catalyst is used in the equilibrium reaction, the catalyst is continuously supplied to the reactive distillation column 1 together with the raw material (A) and / or the raw material (B), or A) Separately from (B), reactive distillation column 1
Continuously. The catalyst and the raw materials (A) and (B)
They may be supplied to the same stage in the reactive distillation column 1,
Further, they may be supplied to different stages. However, in the reactive distillation column 1, as the area where the catalyst is present (reaction stage) is larger, the frequency of contact between the reaction solution and the catalyst is increased, and the reaction efficiency is improved. For this reason, it is preferable to supply the catalyst to the uppermost stage of the reactive distillation column 1 as much as possible. The catalyst may be separated and recovered from the product (C) by using a known method such as distillation. Incidentally, the catalyst may be supplied to the reactive distillation column 1 in a state of being dissolved in an appropriate solvent.

When, for example, a heterogeneous catalyst is used for the equilibrium reaction, the catalyst is held inside the reactive distillation column 1.
When a packed column is used as the reactive distillation column 1,
A heterogeneous catalyst may be packed instead of part or all of the packing packed in the reactive distillation column 1. Reactive distillation column 1
When a plate tower is used, the heterogeneous catalyst may be held in a plate or a downcomer. Further, when a solvent is used for the equilibrium reaction, for example, a solvent supply pipe (not shown) may be separately connected to the reactive distillation column 1 and the solvent may be continuously supplied through the solvent supply pipe.

The reactive distillation apparatus according to the present invention is not limited to the configuration shown in FIG. For example, as shown in FIG. 3, when the number of stages between the stage to which the raw material supply pipe 5 is connected and the stage to which the raw material supply tube 6 is connected is relatively small, the heating provided in the reactive distillation column 1 The number of devices can be reduced to one (the internal heater 14).

Further, the reactive distillation apparatus according to the present invention is
In the case where the equilibrium reaction is subjected to a sequential composite reaction in which two stages are combined, for example, a raw material supply pipe 16 as a third raw material supply pipe may be connected to the reactive distillation column 1 as shown in FIG. In this case, in order to efficiently raise the temperature of the entire region inside the reactive distillation column 1, a stage between the stage to which the raw material supply pipe 5 is connected and the stage to which the raw material supply tube 16 is connected is provided. While the internal heater 14 is provided, the raw material supply pipe 16
It is more preferable to provide the internal heater 15 in a stage between the stage to which is connected and the stage to which the raw material supply pipe 6 is connected.

The raw materials (A), (B) and the third raw material are supplied by using raw material supply pipes 5, 16, and 6 connected to different stages (supply stages) in order from the top of the reactive distillation column 1. Is continuously supplied to the reactive distillation column 1. In this case, the raw material (A) is supplied using the raw material supply pipe 5 so that these raw materials can be brought into sufficient contact with each other,
More preferably, the raw material (B) is supplied using the raw material supply pipe 16 and the third raw material is supplied using the raw material supply pipe 6.

Further, in the reactive distillation apparatus according to the present invention, instead of providing the internal heaters 14 and 15 (FIG. 4), for example, as shown in FIG. 5, two stages (A) ( The reboiler (heating device) 1 is heated outside the stage (A) and returned to, for example, the stage (A), which is the extracted stage, outside the stage (A) (not shown).
It is possible to adopt a configuration in which 7 and 18 are provided. The reboiler 17 is connected to one stage (A) of the reactive distillation column 1 via conduits 17a and 17b. The reboiler 17 heats the reaction solution extracted from the stage (A) through the conduit 17a, and returns the reaction solution to the stage (A) through the conduit 17b. The reboiler 18 is connected to the reactive distillation column 1 via conduits 18a and 18b.
Is connected to the other stage (A). Reboiler 18
Heats the reaction liquid extracted from the stage (A) through the conduit 18a and returns the reaction solution to the stage (A) through the conduit 18b.
That is, the reboilers 17 and 18 heat and circulate the reaction solution. The reboilers 17 and 18 reduce the temperature gradient in the reactive distillation column 1 by heating the reaction solution to make the temperature in the reactive distillation column 1 more uniform,
The temperature of the entire area inside the reactive distillation column 1 is further increased.

The reactive distillation apparatus is not limited to the configuration shown in FIGS. The reactive distillation apparatus and the reactive distillation method according to the present invention can also be applied to a sequential composite reaction in which three or more equilibrium reactions are combined. In this case, for example, the same number of raw material supply pipes as the types of raw materials may be provided in the reactive distillation column.

The equilibrium reaction carried out by using the reactive distillation apparatus and the reactive distillation method according to the present invention is not particularly limited, and examples thereof include a transesterification reaction between an aromatic hydroxy compound and an aliphatic carboxylic acid ester, Transesterification reaction between aromatic carboxylic acid ester and aliphatic carbonate, and aromatic carboxylic acid ester with aliphatic
And a transesterification reaction with an aromatic carbonate. Further, the equilibrium reaction performed using the reactive distillation apparatus and the reactive distillation method may be a sequential complex reaction in which the above-described equilibrium reaction is combined in two or more steps. Compounds produced using the reactive distillation apparatus and the reactive distillation method are not particularly limited. For example, aromatic carboxylic acid esters and aliphatic / aromatic carbonates produced by the above-described equilibrium reaction. And aromatic carbonates.

Next, using the reactive distillation apparatus and the reactive distillation method according to the present invention to carry out a sequential complex reaction in which an equilibrium reaction is combined in two steps, will be described in more detail below with specific examples. explain. In the following description, after transesterification between an aromatic hydroxy compound and an aliphatic carboxylic acid ester, the resulting aromatic carboxylic acid ester is mixed with an aliphatic carbonate and / or an aliphatic carbonate.
Alternatively, a reaction for subjecting an aliphatic / aromatic carbonate to a transesterification reaction to produce an aromatic carbonate as a target product will be exemplified. The transesterification reaction between the aromatic hydroxy compound and the aliphatic carboxylic acid ester is referred to as a first-stage reaction, and the transesterification reaction between the aromatic carboxylic acid ester and the aliphatic carbonate and / or the aliphatic / aromatic carbonate is performed in the second stage. Called reaction.

As the above aromatic hydroxy compound,
Specifically, for example, phenol, o-cresol, m
-Cresol, p-cresol, o-chlorophenol, m-chlorophenol, p-chlorophenol, o
-Ethylphenol, m-ethylphenol, p-ethylphenol, o-isopropylphenol, m-isopropylphenol, p-isopropylphenol, o
-Methoxyphenol, m-methoxyphenol, p-
Examples include methoxyphenol, xylenols, α-naphthol, β-naphthol, and the like, but are not particularly limited. One of these aromatic hydroxy compounds may be used alone, or two or more thereof may be used in combination. Among the compounds exemplified above, phenol is preferred from an industrial viewpoint.

Specific examples of the aliphatic carboxylic acid esters include, for example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, cyclohexyl acetate, benzyl acetate, 2-ethylhexyl acetate, methyl propionate, and propionic acid. Ethyl, propyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, methyl valerate, ethyl valerate, propyl valerate, methyl isovalerate, isoval Examples include, but are not particularly limited to, ethyl valerate, propyl isovalerate, methyl hexanoate, ethyl hexanoate, propyl hexanoate, methyl heptanoate, ethyl heptanoate, and the like.

Specific examples of the aromatic carboxylic acid ester obtained by the first-stage reaction include, for example, phenyl acetate, each isomer of methyl phenyl acetate, each isomer of ethyl phenyl acetate, and each isomer of chlorophenyl acetate ,
Each isomer of isopropylphenyl acetate, each isomer of methoxyphenyl acetate, each isomer of dimethylphenyl acetate,
Each isomer of naphthyl acetate, phenyl propionate, each isomer of methylphenyl propionate, phenyl butyrate, phenyl isobutyrate, phenyl valerate, each isomer of methyl valerate, phenyl isovalerate, phenyl hexanoate, heptane Phenyl acid and the like.

Specific examples of the above-mentioned aliphatic carbonate include, for example, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, diisopropyl carbonate, each isomer of dibutyl carbonate, each isomer of dipentyl carbonate, carbonate Each isomer of dihexyl, each isomer of diheptyl carbonate, each isomer of dioctyl carbonate, each isomer of dinonyl carbonate, each isomer of didecyl carbonate, dicyclohexyl carbonate, dibenzyl carbonate,
Examples include each isomer of diphenethyl carbonate, each isomer of di (methylbenzyl) carbonate, and the like, but are not particularly limited. One of these aliphatic carbonates may be used alone, or two or more thereof may be used in combination. Among the compounds exemplified above, dimethyl carbonate is preferred from an industrial viewpoint.

Examples of the above-mentioned aliphatic / aromatic carbonate include, for example, one of the two aliphatic groups possessed by the aliphatic carbonate, wherein one of the aliphatic groups has an aromatic group possessed by the aromatic carboxylate. Compounds obtained by exchange can be mentioned.

In the former reaction, the aromatic hydroxy compound and the aliphatic carboxylic acid ester are transesterified in the presence of a catalyst to obtain an aromatic carboxylic acid ester.
In the latter reaction, the aromatic carboxylic acid ester is transesterified with the aliphatic carbonate and / or the aliphatic / aromatic carbonate in the presence of a catalyst to obtain an aromatic carbonate. The catalyst used in the first-stage reaction and the catalyst used in the second-stage reaction may be the same as each other, or may be different from each other.

Specific examples of the above-mentioned catalyst include mineral acids such as sulfuric acid; sulfonic acids such as paratoluenesulfonic acid; solid acids such as ion-exchange resins and zeolites; bases such as sodium hydroxide; Metal alkoxides such as isopropoxide and zirconium (IV) isopropoxide; Lewis acids such as aluminum chloride and titanium tetrachloride; and compounds generating Lewis acids; Metal phenoxides such as phenoxylead and phenoxytitanium; lead oxides Lead salts such as lead carbonate; metal acetylacetonate complexes such as zirconium (IV) acetylacetonate, bis (acetylacetonato) copper (II), zinc (II) acetylacetonate and lithium acetylacetonate; dibutyltin oxide And the like; organotin compounds; titanosilicate; metal-substituted aluminum phosphate, and the like. Also, normal protonic acids,
Proton bases, solid acids, and solid bases can also be used as catalysts. These catalysts may be used alone or in combination of two or more. Among the above-mentioned catalysts, a weakly acidic or weakly basic catalyst is more preferable because the selectivity of the product is further improved. A strongly acidic or strongly basic catalyst may cause a decarboxylation reaction which is a side reaction depending on reaction conditions.

When a homogeneous catalyst is used, a mixed solution of the catalyst is supplied into a reactive distillation apparatus. The catalyst can be supplied by mixing with at least one compound of an aromatic hydroxy compound, an aliphatic carboxylic acid ester and an aliphatic carbonate. Alternatively, the solution mixed with the catalyst may be supplied to a supply stage of the aromatic hydroxy compound, aliphatic carboxylic acid ester or aliphatic carbonate ester, or may be supplied to a stage different from the supply stage. However, in the reactive distillation apparatus, as the area (stage) where the catalyst is present increases, the frequency of contact between the reaction solution and the catalyst increases,
The reaction efficiency is improved. For this reason, it is preferred that the catalyst be fed to the highest possible stage of the reactive distillation apparatus.

When a homogeneous catalyst is used, the lower limit of the catalyst concentration is preferably 0.1 p, based on the total amount of the aromatic hydroxy compound and the aliphatic carboxylic acid ester.
pm, more preferably 1 ppm, even more preferably 10 ppm
ppm. The upper limit is an amount that dissolves in a saturated state in the reaction solution inside the reactive distillation apparatus, and is preferably about 1%.
0% by weight, more preferably 5% by weight, still more preferably 1% by weight. When the heterogeneous catalyst is used, the lower limit of the amount of the catalyst is preferably 0.1 to the total amount of the aromatic hydroxy compound and the aliphatic carboxylic acid ester.
It is 1% by weight, more preferably 0.5% by weight, even more preferably 1% by weight. The upper limit is preferably 40
%, More preferably 30% by weight, even more preferably 20% by weight.

The molar ratio of the aromatic hydroxy compound to the aliphatic carboxylic acid ester in the first-stage reaction depends on the type and amount of the catalyst used, the reaction conditions, etc., but is 1: 1.
It is preferably in the range of 100 to 100: 1, and 1:20 to 2
It is more preferably in the range of 0: 1, and even more preferably in the range of 1:10 to 10: 1.

The molar ratio of the aromatic carboxylic acid ester to the aliphatic carbonic acid ester and / or the aliphatic / aromatic carbonic acid ester in the latter reaction depends on the type and amount of the catalyst to be used, the reaction conditions and the like. , 1: 100-10
It is preferably in the range of 0: 1, more preferably in the range of 1:20 to 20: 1, and even more preferably in the range of 1:10 to 10: 1. In the second-stage reaction, the reaction system may contain an aromatic hydroxy compound, an aliphatic carboxylic acid ester, or the like, which is an unreacted product in the first-stage reaction.

In the first-stage reaction and the second-stage reaction, a solvent may be added to the reaction system, that is, the reaction solution, if necessary. Examples of the solvent to be added to facilitate the reaction operation include compounds inert to the above reaction system, for example, ethers, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, and the like. There is no particular limitation. In order to easily remove (evaporate) low-boiling components such as alcohol as a by-product from the reaction system, an inert gas (nitrogen gas, etc.) is introduced into the reaction system from the lower part of the reaction distillation apparatus. You can also.

Factors that determine the operating conditions when operating the reactive distillation apparatus include, for example, the number of stages, operating temperature (reaction temperature), operating pressure, liquid residence time, reflux ratio, and liquid hold-up amount. And the like.

The operating temperature depends on the type of the aromatic hydroxy compound, the aliphatic carboxylic acid ester and the aliphatic carbonate, the type and amount of the catalyst, and other conditions (factors).
It is preferably in the range of 50 ° C to 350 ° C, and 100 ° C to 28 ° C.
The temperature is more preferably within the range of 0 ° C.

The operating pressure may be any of reduced pressure, normal pressure, and increased pressure. In addition, the type of aromatic hydroxy compound, aliphatic carboxylic acid ester and aliphatic carbonate, the type and amount of catalyst, and the other 1 mmH, depending on conditions (factors)
g to 100 kg / cm ² , preferably 5 mmH
g to 50 kg / cm ² is more preferable.

The hold-up amount and the number of stages are closely related to the reaction time, that is, the residence time. That is, to increase the equilibrium conversion, it is necessary to lengthen the residence time to a certain extent, and to extend the residence time, it is necessary to increase the hold-up amount or increase the number of stages.
Of these, it is preferable to increase the hold-up amount, but if it is increased to a certain degree or more, flooding occurs. For this reason, the hold-up amount with respect to the empty column volume (volume) of the reactive distillation apparatus is 0.005 to 0.75 in volume ratio.
Is preferable, and the range of 0.01 to 0.5 is more preferable. When the number of stages is increased, the number of stages is preferably about 2 to 100, taking into account the cost and height limitation when building the reactive distillation apparatus, utility costs, fixed costs, and the like.

The reflux ratio is preferably in the range of 0 to 100, more preferably in the range of 0 to 50, and even more preferably in the range of 0 to 25.

When a heterogeneous catalyst is used, there is no need to separate the catalyst if the catalyst is held in a reactive distillation apparatus. By using a known method, the heterogeneous catalyst can be easily removed and recovered from the reaction solution. In addition, when a homogeneous catalyst is used, the homogeneous catalyst can be easily separated and recovered from the reaction solution by using a known method such as distillation after completion of the reaction. After the completion of the reaction, the catalyst is separated using the above method, and then distilled,
By using a known method such as extraction and recrystallization, the aromatic carbonate as the target substance can be easily isolated.

Then, using, as a reactive distillation apparatus, for example, the reactive distillation column 1 having the structure shown in FIG. 4 or FIG. 5, for example, phenol (aromatic hydroxy compound) and methyl valerate (aliphatic carboxylic acid ester) ) To give a phenyl valerate (aromatic carboxylate), and then a transesterification reaction between the phenyl valerate and dimethyl carbonate (aliphatic carbonate) to give methyl phenyl carbonate (fatty acid). When the target product, diphenyl carbonate (aromatic carbonate) is produced via aromatic / aromatic carbonate, the boiling point of phenol is higher than that of methyl valerate, so phenol is used as a catalyst. , And methyl valerate is continuously supplied through a raw material supply pipe 16, and dimethyl carbonate is continuously supplied through a raw material supply pipe 16. Continuously supplied via the charge supply pipe 6. In this case, the catalyst is shifted from the stage where the raw material supply pipe 5 is connected to the stage where the raw material supply pipe 6 is connected (to the bottom of the tower).
This region becomes a reaction part (reaction stage).

Then, phenol and methyl valerate are subjected to gas-liquid contact, that is, reactive distillation. As a result, the first-stage reaction proceeds, and phenyl valerate and methyl alcohol (by-product) are generated, and both are separated. The phenyl valerate flows down in the reactive distillation column 1. Further, methyl alcohol is continuously extracted as a distillate outside the reaction system.

Next, the above-mentioned phenyl valerate and dimethyl carbonate are subjected to gas-liquid contact, that is, reactive distillation. As a result, the latter-stage reaction proceeds, and diphenyl carbonate and methyl valerate are generated via methylphenyl carbonate, and both are separated. Methyl valerate, which is a by-product, rises in the reactive distillation column 1 and is subjected to the above-mentioned pre-stage reaction. On the other hand, diphenyl carbonate is continuously extracted from the reactive distillation column 1 as a bottom liquid (column liquid) outside the reaction system. That is, diphenyl carbonate is continuously taken out of the reaction system as a bottom liquid.

In the above-mentioned reactive distillation column 1, since the reaction solution is heated using the internal heaters 14 and 15 or the reboilers 17 and 18, the temperature gradient in the reactive distillation column 1 becomes smaller, and therefore, The temperature in the distillation column 1 becomes more uniform, and the temperature in the entire area of the reactive distillation column 1 further rises. Therefore, by performing the above reaction operation,
The reaction rate of the first-stage reaction and the second-stage reaction is faster,
Since the reaction efficiency of these reactions is further improved and the generation of by-products can be suppressed, diphenyl carbonate can be produced efficiently and continuously.

For example, in the case of producing a phenyl valerate by transesterification of phenol and methyl valerate, a reactive distillation column 1 having, for example, the structure shown in FIG. It may be used.

[0072]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 Using a reactive distillation column 1 having the configuration shown in FIG. 4 described above as a reactive distillation apparatus, a sequential complex reaction in which equilibrium reactions were combined in two stages was performed.
However, as the reactive distillation column 1, a column formed by connecting a stainless steel distillation column on a stainless steel plate column was used.

The above tray column has an inner diameter of 20 mm and has 60 stages. And on the top row (1st row)
That is, the raw material supply pipe 5 was connected to the top of the column, the raw material supply pipe 16 was connected to the 40th stage from the top, and the raw material supply tube 6 was connected to the bottom of the lowermost stage (60th stage), that is, to the bottom. Thus, the tray column is the reactor.

Then, instead of using the internal heaters 14 and 15 to internally heat the reaction solution, a heater as a heating device according to the present invention is wound around the platen tower from the top to the 31st to 50th stages. The reaction solution was externally heated by a heater.
Therefore, the number of stages corresponding to the stage (A) is 20 stages. Also, instead of heating the bottom liquid using the reboiler 2,
A heater was wound around the bottom of the tray column and heated by the heater. That is, these heaters supplied heat necessary for distillation.

The above distillation column has a height of 1 m and an inner diameter of 20 mm.
And 3 mmφ stainless steel Dickson packing was filled as a filler. Therefore, the distillation column is a concentration section.

The operating conditions of the reactive distillation column 1 are as follows.
41 ° C., a top pressure of 3.4 kg / cm ² (gauge pressure),
The reflux ratio was 1.9.

Then, phenol 9 as an aromatic hydroxy compound is fed to the reactive distillation column 1 through a raw material supply pipe 5.
A liquid mixture of 8.8% by weight and 1.2% by weight of titanium tetraphenoxide “Ti (OPh) ₄ ” as a catalyst was continuously supplied in a liquid state. The supply amount of the mixed solution per hour was 29.4 g. Further, methyl valerate as an aliphatic carboxylic acid ester was continuously supplied in a gaseous state to the reactive distillation column 1 via a raw material supply pipe 16. The supply amount of methyl valerate per hour was 63.6 g. Further, dimethyl carbonate as an aliphatic carbonate was continuously supplied to the reactive distillation column 1 via a raw material supply pipe 6 in a gaseous state. The amount of dimethyl carbonate supplied per hour is 9.
0 g.

The reaction distillation column 1 is operated under the above operating conditions to perform gas-liquid contact (pre-stage reaction) while transesterifying methyl valerate and phenol, and to form phenyl valerate (aromatic carboxylate). And dimethyl carbonate were subjected to gas-liquid contact (second-stage reaction) while transesterifying. And the generated methylphenyl carbonate (aliphatic
A bottom liquid containing high boiling components such as aromatic carbonate) and diphenyl carbonate (aromatic carbonate) was continuously taken out of the reaction system through the extraction pipe 7. The withdrawal amount of the bottoms per hour was 43.0 g. Further, a distillate containing low-boiling components such as by-produced methyl alcohol was continuously taken out of the reaction system through the extraction pipe 8. The amount of the distillate withdrawn per hour was 59.
It was 0 g.

When the sequential complex reaction reached a steady state, the temperature inside the tray column was measured. As a result, the temperature of the fourth stage from the top was 220 ° C., and the temperature of the fourteenth stage was 226
° C, the temperature of the 24th stage is 228 ° C, and the temperature of the 34th stage is 22
8 ° C, temperature of the 44th stage is 232 ° C, temperature of the 54th stage is 2
The temperature at the bottom was 36 ° C and the temperature at the bottom was 241 ° C. Table 1 shows the column temperatures together with the reflux ratio and the like.

As a result of analyzing the composition of the above distillate, the composition was found to be 89.2% by weight of methyl valerate and 1.6 of dimethyl carbonate.
% By weight and 9.2% by weight of methyl alcohol.

On the other hand, as a result of analyzing the composition of the bottom liquid,
The composition was 15.5% by weight of diphenyl carbonate, 26.6% by weight of phenyl valerate, 15.5% by weight of methyl phenyl carbonate, 8.2% by weight of methyl valerate, 3.1% by weight of dimethyl carbonate, 30% by weight of phenol. 4% by weight and 0.8% by weight of titanium tetraphenoxide. Therefore, the conversion of phenol was 55.0 mol%, and the conversion of dimethyl carbonate was 74.9 mol%. Table 2 shows the flow rates and compositions of the distillate and the bottoms together with the conversion. The conversion rate of dimethyl carbonate is a value expressed as a percentage by dividing the conversion amount of dimethyl carbonate by the supplied amount of dimethyl carbonate.

Example 2 Using the same reactive distillation apparatus as in Example 1, the winding position of the heater as the heating apparatus according to the present invention was changed to the 39th and 42th stages from the top of the plate tower. A composite reaction was carried out successively under the same reaction conditions as in Example 1 except that the two steps were changed to the second step. Therefore, the number of stages corresponding to the stage (A) is two.

The withdrawal amount of the bottoms per hour was 4
It was 3.0 g. The amount of the distillate withdrawn per hour was 59.0 g. When the temperature reached the steady state, the temperature inside the tray tower was measured. As a result, the temperature of the fourth stage from the top was 221 ° C, the temperature of the fourteenth stage was 226 ° C,
The temperature of the 24th stage was 227 ° C, and the temperature of the 34th stage was 229 ° C.
° C, the temperature of the 44th stage is 233 ° C, the temperature of the 54th stage is 23
The temperature at the bottom was 4 ° C and the temperature at the bottom was 242 ° C. Table 1 shows the column temperatures together with the reflux ratio and the like.

As a result of analyzing the composition of the above distillate, the composition was found to be 89.0% by weight of methyl valerate and 1.7 of dimethyl carbonate.
% By weight and 9.3% by weight of methyl alcohol.

On the other hand, as a result of analyzing the composition of the bottom liquid,
The composition was 15.8% by weight of diphenyl carbonate, 27.2% by weight of phenyl valerate, 15.3% by weight of methyl phenyl carbonate, 8.1% by weight of methyl valerate, 2.9% by weight of dimethyl carbonate, and 29% by weight of phenol. 9% by weight and 0.8% by weight of titanium tetraphenoxide. Therefore, the conversion of phenol was 55.7 mol%, and the conversion of dimethyl carbonate was 75.0 mol%. Table 2 shows the flow rates and compositions of the distillate and the bottoms together with the conversion.

Comparative Example 1 The same reaction distillation apparatus as in Example 1 was used, except that the heater as the heating device according to the present invention was not used. Under the conditions, a complex reaction was sequentially performed. That is, the heat necessary for distillation was supplied by heating only with the heater wound around the bottom of the tray column.

The amount of withdrawn liquid per hour was 4
2.0 g. The amount of the distillate withdrawn per hour was 60.0 g. When the temperature reached the steady state, the temperature inside the tray tower was measured. As a result, the temperature of the fourth stage from the top was 192 ° C, the temperature of the fourteenth stage was 193 ° C,
The temperature of the 24th stage was 193 ° C, and the temperature of the 34th stage was 193 ° C.
° C, the temperature of the 44th stage is 191 ° C, and the temperature of the 54th stage is 19 ° C.
The temperature at the bottom of the column was 241 ° C. Table 1 shows the column temperatures together with the reflux ratio and the like.

As a result of analyzing the composition of the above distillate, the composition was found to be 83.7% by weight of methyl valerate and 10.3% of dimethyl carbonate.
5% by weight and 5.8% by weight of methyl alcohol.

On the other hand, as a result of analyzing the composition of the above bottom liquid,
The composition comprises 4.5% by weight of diphenyl carbonate, 31.9% by weight of phenyl valerate, 5.4% by weight of methylphenyl carbonate,
Methyl valerate 11.1% by weight, dimethyl carbonate 1.2% by weight, phenol 45.0% by weight, and titanium tetraphenoxide 0.8% by weight. Therefore, the conversion of phenol was 35.0 mol%, and the conversion of dimethyl carbonate was 24.2 mol%. Table 2 shows the flow rates and compositions of the distillate and the bottoms together with the conversion.

[0091]

[Table 1]

[0092]

[Table 2]

Example 3 Reactive distillation was carried out using a reactive distillation column 1 having the configuration shown in FIG. 3 as a reactive distillation apparatus. However, the reactive distillation column 1 has an inner diameter of 55 mm.
A stainless steel packed column was connected to a stainless steel packed column. Hereinafter, the packed column of the reactive distillation column 1 used in the present example will be briefly described.

As shown in FIG. 6, the packed column 20 is
Inside, a filler layer 21, a rising part 22, a liquid storage part 23 and the like are provided. The packing layer 21 is formed on a perforated plate 21a through which a reaction gas can pass, and is filled with 3 mmφ as a packing.
Stainless steel Dickson packing (not shown). Further, a perforated plate 21b through which the reaction gas can pass is placed on the packing. The packing layer 21 is configured to bring a reaction liquid descending in the column and a reaction gas rising in the column into gas-liquid contact.

Below the filling layer 21, a collector 25 comprising a funnel portion 25a formed in a funnel shape and a leg portion 25b formed in a tubular shape is provided. Funnel part 25a
Is made of stainless steel wire mesh. Leg 25b
Is inserted into the liquid reservoir 23, and the reaction liquid collected in the funnel 25 a is introduced into the liquid reservoir 23.

The rising portion 22 is provided on the upper side of the packing layer 21 (the lower packing layer in FIG. 6), and is disposed at the peripheral portion in the horizontal section of the tower. The rising portion 22
The reaction gas is raised substantially without gas-liquid contact.

The liquid reservoir 23 is formed in a cylindrical shape with a bottom and has a capacity of 25 ml. The liquid reservoir 23 is provided with the filler layer 2.
1 (the lower packing layer in the figure) is provided on the upper side, and is provided at the center of the horizontal section.
The liquid reservoir 23 is provided with a filler layer 21 provided on the upper side thereof.
The reaction liquid that has descended from the (filler layer at the upper side in the figure) via the collector 25 can be stored. The liquid reservoir 23 reacts the raw materials in the reaction liquid in the presence of the catalyst without substantially bringing them into gas-liquid contact.

The reaction liquid stored in the liquid storage part 23 is 25 m
When the value becomes 1 or more, the reaction liquid overflows from the liquid reservoir 23 and overflows, descends in the column along the outer wall of the liquid reservoir 23, and is supplied to the packing layer 21 provided on the lower side.

The packed tower 20 having the above-described structure includes a packed bed 21,
The number of stages of the unit including the liquid reservoir 23 and the rising portion 22 is five. And the uppermost stage (first stage) of the packed tower 20
, That is, the raw material supply pipe 5 is connected to the top,
The raw material supply pipe 6 was connected to the bottom of the column, that is, to the bottom of the column. Therefore, the packed tower 20 is a reaction section.

Then, instead of using the internal heater 14 to internally heat the reaction solution, a heater as a heating device according to the present invention was wound around the entire packed tower 20, and the reaction solution was externally heated by the heater. Therefore, the number of stages corresponding to the stage (A) is five. Instead of using the reboiler 2 to heat the bottom liquid, a heater was wound around the bottom of the packed tower 20 and heated by the heater. That is, these heaters supplied heat necessary for distillation.

The above distillation column had a height of 80 cm and an inner diameter of 20 mm, and was filled with a 3 mmφ stainless steel Dickson packing as a packing material. Therefore, the distillation column is a concentration section.

The operating conditions of the reactive distillation column 1 are as follows.
At 30 ° C., the top pressure was 350 Torr, and the reflux ratio was 0.7.

Then, a mixed liquid as a raw material was continuously supplied to the reactive distillation column 1 via a raw material supply pipe 5 in a liquid state. The supply amount of the mixed liquid per hour was 122.2 g.
The composition of the mixture was 25.2% by weight of phenyl valerate, 17.6% by weight of methyl phenyl carbonate, 16% by weight of methyl valerate.
6% by weight, 5.8% by weight of dimethyl carbonate, phenol 2
5.0% by weight, 0.4% by weight of titanium tetraphenoxide, and 9.4% by weight of diphenyl carbonate as an object
Met.

Further, dimethyl carbonate was continuously supplied to the reactive distillation column 1 via the raw material supply pipe 6 in a gaseous state. The supply amount of dimethyl carbonate per hour was 15.3 g.

The reactive distillation column 1 was operated under the above operating conditions, and reactive distillation was performed. Then, the bottoms containing the high-boiling components were continuously taken out of the reaction system. The withdrawal amount of the bottoms per hour was 50.0 g. Also,
The distillate containing the low boiling point component was continuously taken out of the reaction system. The amount of distillate withdrawn per hour was 88.0.
g.

When the reaction distillation reached a steady state, the internal temperature of the packed column 20 was measured. As a result, the temperature of the first stage from the top was 162 ° C., and the temperature of the third stage was 186 ° C.
The temperature at the 5th stage was 210 ° C, and the temperature at the bottom of the column was 228 ° C. Table 3 shows the temperatures in the tower together with the reflux ratio and the like.

As a result of analyzing the composition of the distillate, the composition was determined to be 40.7% by weight of methyl valerate and 24.
It was 6% by weight, 34.6% by weight of phenol, and 0.1% by weight of methyl alcohol.

On the other hand, as a result of analyzing the composition of the bottom liquid,
The composition was 77.3% by weight of diphenyl carbonate, 13.8% by weight of phenyl valerate, 7.0% by weight of methyl phenyl carbonate, 0.2% by weight of methyl valerate, 0.3% by weight of dimethyl carbonate, and 0.3% by weight of phenol. 2% by weight and 1.0% by weight of titanium tetraphenoxide. Therefore, the conversion of phenyl valerate was 77.6 mol%. Table 4 shows the flow rates and compositions of the distillate and the bottoms together with the conversion.

[Example 4] Using the same reactive distillation apparatus as that of Example 3, the winding position of the heater as the heating apparatus according to the present invention was set to 4
Reactive distillation was carried out under the same reaction conditions as in Example 3 except that it was changed to a single stage. Therefore, the number of stages corresponding to the stage (A) is one.

The withdrawal volume of the bottoms per hour was 5
0.0 g. The amount of the distillate withdrawn per hour was 88.0 g. Then, when the steady state was reached, the internal temperature of the packed tower 20 was measured. As a result, the temperature of the first stage from the top was 159 ° C., and the temperature of the third stage was 1
84 ° C., temperature at the 5th stage is 210 ° C., temperature at the bottom of the column is 229
° C. Table 3 shows the column temperature along with the reflux ratio, etc.
Shown in

As a result of analyzing the composition of the distillate, the composition was determined to be 40.8% by weight of methyl valerate, 24.
5% by weight, 34.6% by weight of phenol and 0.1% by weight of methyl alcohol.

On the other hand, as a result of analyzing the composition of the bottom liquid,
The composition was 77.4% by weight of diphenyl carbonate, 13.8% by weight of phenyl valerate, 7.1% by weight of methyl phenyl carbonate, 0.2% by weight of methyl valerate, 0.3% by weight of dimethyl carbonate, and 0.3% by weight of phenol. 2% by weight and 1.0% by weight of titanium tetraphenoxide. Therefore, the conversion of phenyl valerate was 77.5 mol%. Table 4 shows the flow rates and compositions of the distillate and the bottoms together with the conversion.

Comparative Example 2 The same reaction distillation apparatus as in Example 3 was used, except that the heater as the heating device according to the present invention was not used. Under the conditions, reactive distillation was performed. That is, the heat required for distillation was supplied by heating only with the heater wound around the bottom of the packed tower 20. The reflux ratio is
0.8.

The withdrawal volume of the bottoms per hour was 5
It was 4.0 g. The amount of the distillate withdrawn per hour was 84.0 g. Then, when the steady state was reached, the internal temperature of the packed tower 20 was measured. As a result, the temperature of the first stage from the top was 154 ° C., and the temperature of the third stage was 1
65 ° C., temperature at the 5th stage is 190 ° C., temperature at the bottom of the column is 229
° C. Table 3 shows the column temperature along with the reflux ratio, etc.
Shown in

As a result of analyzing the composition of the above distillate, the composition was found to be 36.4% by weight of methyl valerate and 28.80% of dimethyl carbonate.
It was 4% by weight, 35.1% by weight of phenol, and 0.1% by weight of methyl alcohol.

On the other hand, as a result of analyzing the composition of the bottom liquid,
The composition was 65.2% by weight of diphenyl carbonate, 27.5% by weight of phenyl valerate, 4.5% by weight of methyl phenyl carbonate, 0.1% by weight of methyl valerate, 0.1% by weight of dimethyl carbonate, 1. 5% by weight and 1.0% by weight of titanium tetraphenoxide. Therefore, the conversion of phenyl valerate was 52.1 mol%. Table 4 shows the flow rates and compositions of the distillate and the bottoms together with the conversion.

[0117]

[Table 3]

[0118]

[Table 4]

As is evident from the results of Examples 1 to 4 and Comparative Examples 1 and 2, the reactive distillation column and the reactive distillation method according to the present invention were employed.
The temperature gradient inside the column 1 can be made smaller, the temperature inside the column 1 can be made more uniform, and the reaction amount can be increased without increasing the amount of heat supplied from a heater (tower heating device) wound around the column bottom. It can be seen that the temperature in the entire area inside the distillation column 1 can be further increased. Therefore, it is found that by increasing the reaction rate of the equilibrium reaction, the reaction efficiency (equilibrium conversion) of the equilibrium reaction can be further improved, and the generation of by-products can be suppressed.

[0120]

According to the reactive distillation apparatus of the present invention,
The temperature gradient in the reactive distillation apparatus can be made smaller, the temperature in the apparatus can be made more uniform, and the amount of heat supplied from a bottom heating device such as a reboiler provided at the bottom can be increased. Without this, the temperature in the entire area within the reactive distillation apparatus can be further increased. Accordingly, it is possible to provide a reactive distillation apparatus capable of further improving the reaction efficiency of the equilibrium reaction by increasing the reaction rate of the equilibrium reaction and suppressing the generation of by-products. It has the effect of being able to do it.

Further, according to the reactive distillation method of the present invention, the temperature gradient in the reactive distillation apparatus can be made smaller, the temperature in the apparatus can be made more uniform, and the reactive distillation apparatus can be provided at the bottom of the column. Without increasing the amount of heat supplied from a tower bottom heating device such as a reboiler, the temperature of the entire region inside the reactive distillation device can be further increased. Accordingly, it is possible to provide a reactive distillation method that can further improve the reaction efficiency of the equilibrium reaction by increasing the reaction rate of the equilibrium reaction, and can suppress the generation of by-products. It has the effect of being able to do it.

Further, according to the reactive distillation method of the present invention, at least one ester selected from the group consisting of aromatic carboxylic esters, aliphatic / aromatic carbonates, and aromatic carbonates can be produced with higher efficiency. This has the effect of being able to be manufactured in an efficient manner. The ester is an industrially useful compound. For example, diphenyl carbonate, which is a kind of aromatic carbonate, is used as a raw material for polycarbonate.

[Brief description of the drawings]

FIG. 1 is a graph showing a difference between a temperature gradient in a reactive distillation apparatus when a reactive distillation method according to the present invention is performed and a temperature gradient when a conventional reactive distillation method is performed.

FIG. 2 is a block diagram showing a schematic configuration of a reactive distillation apparatus suitable for a reactive distillation method according to one embodiment of the present invention.

FIG. 3 is a block diagram showing a schematic configuration of another reactive distillation apparatus suitable for the reactive distillation method according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of still another reactive distillation apparatus suitable for the reactive distillation method according to one embodiment of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of still another reactive distillation apparatus suitable for the reactive distillation method according to one embodiment of the present invention.

FIG. 6 is a sectional view of a main part showing a schematic configuration of a packed column included in a reactive distillation column in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactive distillation tower (reactive distillation apparatus) 2 Reboiler (tower heating apparatus) 5.6 Raw material supply pipe 14.15 Internal heater (heating apparatus) 16 Raw material supply pipe 17.18 Reboiler (heating apparatus) 20 Packing tower 21 Packing Layer 22 Ascending part 23 Liquid reservoir 25 Collector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C07C 69/24 C07C 69/24 69/96 69/96 Z F term (reference) 4D076 AA07 AA16 AA22 AA24 BB04 BB05 CA19 DA14 DA22 EA02Y EA08Y EA12X EA14X EA17X FA02 FA12 JA03 4H006 AA02 AA04 AC48 AD11 BD20 BD21 BD81 BJ50 KA02 KA03

Claims (7)

[Claims] 1. A reactive distillation apparatus having three or more stages for performing an equilibrium reaction, wherein at least one of the reaction stages (A) excluding a column bottom and a supply stage for supplying a raw material. And a heating device for heating the reaction solution. 2. The reactive distillation apparatus according to claim 1, wherein the heating device is provided inside the stage (A) so as to internally heat the reaction solution present in the stage (A). . 3. The reactive distillation apparatus according to claim 1, wherein the heating device is provided outside the stage (A) to externally heat the reaction solution present in the stage (A). . 4. The apparatus according to claim 1, wherein the heating device is provided outside the reaction stage so as to heat the reaction liquid extracted from the stage (A) and return it to the reaction stage. Reactive distillation equipment. 5. The reactive distillation apparatus according to claim 4, wherein the heated reaction liquid is returned to the stage (A). 6. A reactive distillation method performed using a reactive distillation apparatus having three or more stages, wherein at least one of the reaction stages (A) excluding a column bottom and a supply stage for supplying a raw material. A reactive distillation method, wherein an equilibrium reaction is carried out while heating a reaction solution present in the reaction solution. 7. The above equilibrium reaction includes a transesterification reaction between an aromatic hydroxy compound and an aliphatic carboxylic acid ester, a transesterification reaction between an aromatic carboxylic acid ester and an aliphatic carbonic acid ester, and a reaction between an aromatic carboxylic acid ester and an aliphatic carboxylic acid ester. 7. The reactive distillation method according to claim 6, wherein the reaction distillation is at least one transesterification selected from the group consisting of transesterification with an aliphatic / aromatic carbonate.