JPH08143512A - Process and apparatus for producing unsaturated carboxylic acid ester - Google Patents

Abstract

PURPOSE: To provide a method for producing an unsaturated carboxylic acid esters, providing an excellent yield and conversion by using an esterification reaction of an alcohol; and an unsaturated carboxylic acid.

CONSTITUTION: This method for producing an unsaturated carboxylic acid ester comprises circulating reactants so as to flow in a reactor constituted of 1-10 separated and fixed steps consisting of each step comprising a catalyst layer 2, a filter 3 and an air-charging opening, and having insulating outer walls, downward so as to successively contact with the catalyst layers, supplying the evaporation heat for extracting the formed water by an heat-exchanger 10 at the exterior of the reactor, circulating the reactants between the reactor and the heat exchanger by a circulating pump, bringing an azeotropic composition of the evaporated water and alcohol into contact with the alcohol returning in a column or the feedstock alcohol supplied from an alcohol-supplying opening, returning high boiling point components to the reactor, liquefying light components at a condenser 17, separating the condensed liquid into an organic layer and the water by decantation, returning the organic layer to the reactor, and removing the produced water.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for producing unsaturated carboxylic acid esters and an apparatus for producing the same.

More specifically, it is an esterification reaction of an (aliphatic) alcohol having 1 to 8 carbon atoms with an unsaturated carboxylic acid, which is a corresponding unsaturated carboxylic acid ester utilizing a cation exchange resin catalyst. In the method of manufacturing
The present invention relates to a method of maintaining a high yield, suppressing the formation of a polymer as much as possible, maintaining a constant conversion regardless of the activity of a catalyst, and extending the life of the catalyst.

[0003]

2. Description of the Related Art Conventionally, in the esterification reaction of an alcohol with an unsaturated carboxylic acid as described above, it is difficult to obtain a high conversion rate to an ester because the reaction rate is slow and the equilibrium constant is relatively low. There is a problem.

In addition, the esterification of alcohol or the polymerization reaction of (meth) acrylic acid does not proceed sufficiently during the esterification reaction, and it is difficult to increase the yield of the ester product.

At present, a commercially available method for producing the above ester product is a glass lined batch.
There is a method in which the reactivity is increased by using an acid catalyst such as sulfuric acid or paratoluenesulfinic acid using a reactor, and the water produced during the reaction is continuously extracted to induce the reaction to the normal reaction side.

However, in such a method, the cost of the reactor is very high, and the catalyst used must be neutralized with a base such as NaOH, so that there are many disadvantages in terms of economic efficiency and amount of waste water. Exists.

Recently, polystyrene and D
Copolymer of VB (divinyl benzene) with sulfonic acid (SO ₃
The strong cation exchange resin with H) is used as a catalyst for the production of the unsaturated carboxylic acid ester, and is used for improving the economical efficiency of the process and designing the continuous process.

[0008] In particular, JP-A-49-54326 discloses a fluidized bed type reactor in which a large amount of inert gas is blown from the bottom of the reactor to suspend the catalyst in the reaction product. In the reactor having such a form, it is difficult to maintain a vacuum when depressurizing the water produced during the reaction in order to extract it. Further, since a large amount of gas is used, there are many economical disadvantages.

Further, in Japanese Patent Laid-Open No. 63-017844, CSTR (continuous stirred te) is applied to the ester reaction.
Techniques using a reactor of the form k reactor) have been disclosed. However, although this reactor is useful for mass transfer in the reactor and suspension of the catalyst, it is said that the cation exchange resin has a very weak mechanical strength, so that the catalyst is easily broken by stirring and the catalytic activity becomes low. The point is the problem.

Japanese Patent Publication No. 62-39150 discloses a reactor in which a fixed-bed type inner and outer jacket is installed, and water produced in the reaction is vaporized and extracted to increase the reaction yield. Has been done.

However, in the reactor of such a form, the catalyst near the wall surface of the reactor loses its activity due to heat, and the high temperature of the wall surface causes the polymerization reaction to proceed rapidly, resulting in (meth) acrylic acid and its ester. There is a problem that a polymer is produced. Also, the reaction product water is difficult to extract smoothly.

[0012]

As described above, this is an esterification reaction of an alcohol (aliphatic having 1 to 8 carbon atoms) with an unsaturated carboxylic acid, which is achieved by using a cation exchange resin as a catalyst. There are various conventional techniques for producing unsaturated carboxylic acid esters, but all of them have problems in terms of reaction yield, catalyst life and catalyst life.

The present invention has been made as a result of extensive studies to solve the above problems, and is an esterification reaction of an alcohol (aliphatic having 1 to 8 carbon atoms) with an unsaturated carboxylic acid. In a method for producing corresponding unsaturated carboxylic acid esters by using a cation exchange resin as a catalyst, water produced during the reaction is continuously extracted to induce the reaction in the direction of positive reaction and the cation exchange is performed. By increasing the contact opportunity and contact time between the resin catalyst and the reactants, and by using the method in which the area where the catalyst is present is not directly heated, the high yield is maintained and the production of the polymer is suppressed as much as possible. It is an object of the present invention to provide a method for maintaining a constant conversion rate regardless of activity and maximizing catalyst life.

[0014]

In order to solve the above problems, the present invention provides a cation exchange in an esterification reaction between an (aliphatic) alcohol having 1 to 8 carbon atoms and an unsaturated carboxylic acid. In a method for continuously producing unsaturated carboxylic acid esters using a resin as a catalyst, 1
In the form of a fixed bed separated into 10 stages, each stage is composed of a catalyst layer, a filter, an air inlet, and an outer wall is a heat insulating reactor. It circulates in contact and supplies heat of vaporization for extraction of produced water through a heat exchanger outside the reactor, circulates the reactants between the reactor and the heat exchanger through a circulation pump, and vaporizes by the heat exchanger. The azeotropic composition of water and alcohol, and the alcohol refluxed in the column tower or the raw material alcohol supplied from the alcohol supply port at the top of the column tower are brought into contact with each other, and the high boiling point component is refluxed in the reactor, The light components are moved to the upper part of the column and liquefied by a condenser, separated into an organic layer and water by a dicant, and then the organic layer is refluxed,
The produced water is characterized by being removed.

An apparatus for continuously producing unsaturated carboxylic acid esters by utilizing a cation exchange resin catalyst in an esterification reaction of an (aliphatic) alcohol having 1 to 8 carbon atoms and an unsaturated carboxylic acid. In the reactor, the reactor (22) is in the form of a fixed bed separated into 1 to 10 stages, and each stage is a catalyst layer (2), a filter (3), an air inlet (4) and an outer wall is adiabatic. Through which the reactant circulates continuously in contact with the catalyst layer from top to bottom, and heat of vaporization is supplied through a heat exchanger (10) outside the reactor to extract product water,
A circulation pump (8) circulates the reaction product between the reactor and the heat exchanger, and the azeotropic composition of water and alcohol vaporized by the heat exchanger is refluxed in the column tower (15). Alcohol supply port (2) at the top of 15)
After contacting the raw material alcohol supplied from 3), the high boiling point component is refluxed to the reactor, the light component is moved to the upper part of the column, liquefied by the condenser, and separated into the organic layer and water by the dicant (18). There is also provided a device characterized in that the organic layer is refluxed and the produced water is removed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above problems, the present invention will be described with reference to the drawings assuming that a manufacturing process particularly adapted to the present invention and a (specially designed) reactor system are configured as follows. To do.

FIG. 1 is an explanatory view of an apparatus for producing unsaturated carboxylic acid esters according to an embodiment of the present invention.

In this figure, the raw material is a pipe (1).
Flowed into the reactor through the Fakquid column (15)
And a high-boiling point reactant flowing in the heat exchanger (10) are mixed in the upper part of the reactor and flow through the catalyst layer in the reactor from top to bottom to proceed the reaction.

The reactor is in the form of a fixed bed separated into 1 to 10 stages, (2) represents a catalyst layer and (3) represents a filter. Further, the outer wall of the reactor is insulated so as to maintain only the reaction temperature, and the heat of vaporization for extracting the produced water is provided by the heat exchanger (10) outside the reactor.

Steam or heat medium is introduced through the pipe (11) in order to supply heat to the heat exchanger. The entire system is maintained at reduced pressure and the reaction temperature is maintained at the bubbling point of the reactants.

Since a polymerization inhibitor in the form of penolic is used to prevent polymer formation, a small amount of air is supplied through pipes (4) and (9) to prevent polymerization. The circulation pump (8) is used to circulate the reactant at a high flow rate between the reactor and the heat exchanger, and the heat exchanger (1
Extraction of the produced water according to 0) is carried out to obtain a high conversion rate.

At this time, the conversion rate can be adjusted to some extent by the flow rate of the reactants sent by the circulation pump (8). That is, when a large amount of the reaction product is circulated, the reaction due to contact with the catalyst layer and the extraction of the produced water in the heat exchanger increase, and the conversion rate increases.

By utilizing this characteristic, the composition after the reaction product passes through the reactor can be maintained to some extent constant even when the activity of the catalyst is high or the activity of the catalyst is low, and the purified portion can be stabilized. Help to drive to.

The reactant is supplied to the circulation pump (8) through the pipe (5), and the product is obtained through the pipe (6).

The catalyst and the reactant are continuously separated by using the filter (3). The azeotropic composition of water and alcohol vaporized by the heat exchanger (10) flows into the column (15) through the pipe (13) together with some vaporized acid, and comes into contact with the alcohol refluxed in the column tower to generate acid. The high boiling point components are refluxed to the reactor.

The light components are moved to the upper part of the column, liquefied in the condenser (17), separated into an organic layer and an aqueous layer by a dicant (18), and then the organic layer is refluxed through a pipe (19), and a pipe ( The produced water is removed through 20).

When the raw material alcohol is supplied from the alcohol supply port (23) at the top of the column (15), the (meth) acrylic acid present in the column (15) is absorbed by the raw material alcohol. The (meth) acrylic acid is not substantially contained in the overhead oil.

Therefore, (meth) acrylic acid is not substantially contained in the aqueous layer obtained after the condensation separation,
This water layer can be discharged as it is without any special treatment.

Further, since (meth) acrylic acid is collected by this alcohol and returned to the column (15), its loss is substantially eliminated.

The refluxed alcohol and acid are piped (1
After entering the reactor through 4), participate in the reaction again.
The amount circulated in the reactor and the production amount are regulated through the regulating valve (7), but the ratio of the circulation amount and the production amount is maintained at 10: 1 or more.

As the reactants pass through the heat exchanger (10),
The azeotropic components of water and alcohol or ester having a low boiling point are vaporized, and the remaining high boiling components are in liquid form and circulated to the reactor through the pipe (21).

The catalyst used in the reaction was Diaion PK-228 (Mits
ubishi chemical industries.Ltd.), XH-2071 (Rohm & H
ass), Dowex monosphere 650 CH (Dow chemical Co.), etc., and a strong cation exchange resin having an ion exchange capacity of 1.2 to 2.05 (meq / ml).

The molar ratio of unsaturated carboxylic acid to alcohol is generally known to be about 1: 0.5 to 1: 2.

If the alcohol is introduced in an excessive amount, the reaction conversion rate increases, but a large amount of energy is required for alcohol separation in the refining process, which is unsuitable in terms of energy. If the acid flows in too much, not only the separation but also the equipment will be corroded, so the water ratio is 1: 1.
Is preferred. In the present invention, the reaction molar ratio is 1:08.
Adapted to ˜1: 1.3.

In the present invention, acrylic acid or methacrylic acid is used as the unsaturated carboxylic acid. If the reaction temperature is too low, the reaction temperature will be slow, and if it is too high, the production of by-products and catalytic thermal decomposition will increase, so a temperature in the range of about 70 to 100 ° C. is suitable.

The reaction pressure is 50 to 400 (torr) so that the water produced during the reaction can be smoothly extracted in the heat exchanger even at the reaction temperature.
Depressurize with a degree. In order to prevent the formation of polymer during the reaction, about 100 to 500 pp of a polymerization inhibitor in the form of penoliq is added together with air.
Use about m.

The raw material alcohol supplied from the alcohol supply port at the top of the column is brought into contact reflux with the azeotropic composition of vaporized water and alcohol, and the (meth) acrylic acid that is accompanied and flows out in the generated water is discharged from the generated water. Separate and collect.

In the recovery of the active ingredient, particularly (meth) acrylic acid, by this raw material alcohol, the amount of the raw material alcohol refluxed for fluid contact is 10% by weight with respect to the alcohol supplied for the esterification reaction. The above is preferable, but 30 to 80% by weight is particularly preferable. If less than this, there is a risk that (meth) acrylic acid will not be recovered.

An embodiment using the device corresponding to FIG. 1 will be described below. These examples do not limit the present invention, and the units to be used can also be used by converting them into commercially larger units such as m, KL and Atm.

Example 1 A reactor made of glass and having a reactant volume of 3.5 L was used. In addition, a shell and tube heat exchanger made of glass was provided in the reactor, and a glass filter was used which could be separated by the reactor.

A small magnetic pump was used as the circulation pump, and the flow rate of the circulated reactant was adjusted using a flow controller. First, the molar ratio of butanol and acrylic acid is about 1:
Mix to make 1 to make a reactant of constant composition,
Hydroquinone, a polymerization inhibitor, based on acrylic acid weight
Diaion PK-228, XH was added in an amount of 0.05% and stored in a storage cabinet, and then dried in an oven at a temperature of about 70 ° C.
-2071, monosphere 650CH catalyst was charged to a 2.8L (dry catalyst basis) reactor.

After flowing into a part of the raw material reaction product and circulating the reaction product for about 2 hours and 30 minutes and raising the temperature at a temperature of about 75 ° C., the flow rate of the raw material is about 1 (L / hr) continuously. It was allowed to flow in with a small amount of air.

From the beginning of the reaction, the pressure was maintained at about 150 (torr), and the produced water was continuously vaporized using a heat exchanger and extracted through the distillation column. The flow rate of the reactant circulated at this time was about 25 (L / hr).

When the continuous operation was performed for 24 hours, the composition of the reaction product was about 0.26% water and about 2 butanol.
There were 3.995%, butyl acrylate about 63.942%, acrylic acid about 10.55%, dibutyl ether about 1.18%, and dimer acid ester about 0.0005%.

In this reaction, the acrylic acid standard conversion rate was about 77.4.
3%, and the acrylic acid standard selectivity is 99.3 (mol
%)Met.

Example 2 The same experimental equipment as in Example 1 was used.

The reactor was filled with 920 (ml) of Amberlyst 39C catalyst dried in an oven at 70 ° C. for 24 hours or more, and the composition was 30.70% of acrylic acid (Acrylic acid).
2-Ethyl-hexanol 56.67%,
2-Ethyl-hexyl acrylate
After adding the same amount of hydroquinone as in Example 1 to a raw material having crylate) of 12.15% and water content of 0.48%, the appropriate amount was added all at once to the reactor and the temperature was raised to 80 ° C while circulating to raise the pressure to 77 (mmHg ) Fixed.

Then, after reacting while removing water in the distillation tower for about 1 hour and 40 minutes, the raw materials and a small amount of air were continuously introduced. At this time, the total inflow rate of raw material is 687.84.
(G / hr), and 30% of 2-ethyl-hexanol (2-Ethyl-hexanol) in the inflowing raw material flowed into the upper stage of the water separation distillation column.

The liquid particles in the reactor were kept constant so that the residence time was 100 minutes, and the flow rate of the reactant circulated in the reactor was fixed at 10 L / hr.

When equilibrium is reached after 24 hours of continuous operation, the composition of the reaction product is 13.49% acrylic acid (Acrylic acid), 2-
Ethyl-hexanol (2-Ethyl-hexanol) 25.62%, 2-
2-Ethyl-hexyl acryl
ate) 60.16%, water content 0.52%, 2-ethyl-hexyl ester of dimeric acid (2-Ethyl-hexyl Ester)
0.15%, 2-ethyl-hexyl propionate (2-ethyl
-hexyl propionate) 0.01% was present.

In this reaction, the acrylic acid (Acrylic acid) standard conversion rate was about 57.59%, and the acrylic acid (Acrylic acid)
The reference selectivity was about 99.57 (mol%). Moreover, the amount of acrylic acid (Acrylic acid) flowing out to the upper part of the distillation column was extremely small, which was difficult to analyze accurately.

Example 3 The same experimental apparatus as in Example 1 was used.

A reactor was filled with 920 ml of Amberlyst 39C catalyst which had been dried in an oven at 70 ° C. for 24 hours or more, and the composition was 34.52% of acrylic acid (Acrylic acid), 2-Ethyl-hexanol (2-Ethyl-hexanol). ) 65.48%,
An appropriate amount of raw material to which hydroquinone was added in the same amount as in Example 1 was put into a reactor all at once and the temperature was adjusted to 80 while circulating.
Raise it to ℃ and fix the pressure at 77 (mmHg),
After reacting while distilling water into the distillation column for 40 minutes, raw materials and a small amount of air were continuously introduced.

At this time, the total feeding speed of the raw materials was 698.46 (g /
2-h-hexanol (2-Eth) in the raw material
30% of yl-hexanol) flowed into the upper stage of the water separation distillation column. The liquid level in the reactor was kept constant so that the residence time was 100 minutes, and the flow rate of the reactant circulated in the reactor was fixed at 10 (L / hr).

When the equilibrium was reached after 24 hours of continuous operation, the composition of the reaction product was 12.63% acrylic acid (Acrylic acid), 2-
Ethyl-hexanol (2-Ethyl-hexanol) 25.96%, 2-
2-Ethyl-hexylacryla
te) 60.65%, water 0.50%, dimeric acid 0.08
%, 2-ethyl-hexyl ester of dimeric acid (2-Ethyl-hexyl Ester) 0.16%, 2-ethyl-hexyl propionate 0.02
% Was present.

In this reaction, the acrylic acid (Acrylic acid) standard conversion rate (conversion) was about 65%, and the acrylic acid (Acrlic acid)
ylic acid) Standard selectivity (selectivity) is about 99.52 (mol
%)Met.

Acrylic acid to the top of the distillation tower
The outflow was extremely small as in Example 2.

[0058]

EFFECT OF THE INVENTION An esterification reaction of an alcohol (aliphatic having 1 to 8 carbon atoms) with an unsaturated carboxylic acid,
In the method for producing a corresponding unsaturated carboxylic acid ester using a cation exchange resin as a catalyst, water produced during the reaction is continuously extracted, so that the reaction proceeds in a positive reaction direction.

Also, a high yield can be obtained by increasing the contact opportunity and contact time between the cation exchange resin catalyst and the reactants and by not directly heating the area where the catalyst is present.

Further, since the production of the polymer is suppressed as much as possible, the conversion rate is maintained constant regardless of the activity of the catalyst, and the life of the catalyst is extended to the maximum extent.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a reactor which is a main part for carrying out the present invention.

[Explanation of symbols]

1, 4, 5, 6, 9, 11, 12, 13, 14, 16,
19, 20, 21 ... Pipe 2 ... Catalyst layer 3 ... Filter 7 ... Pump 8 ... Circulation pump 10 ... Heat exchanger 15 ... Funk column 17 ... Condenser 18 ... Dicant 22 ... Reactor 23 ... Alcohol supply port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gwangho Park South Korea, Daejeonsi, Yousung, Shinseongdong, Lucky Hana APT. 102-701 (72) Inventor Famyungju South Korea, Daejeonsi, Yousung, Dryongdong, 386 -4, Lucky APT. B-206 (72) Inventor Han Sung Lee, Korea, Seoul, Gangnamuk, Samsung Dong, 54-6, Hyosung Villa. 41-306

Claims (8)

[Claims] 1. An unsaturated carboxylic acid ester is continuously produced by using a cation exchange resin as a catalyst in an esterification reaction of an (aliphatic) alcohol having 1 to 8 carbon atoms with an unsaturated carboxylic acid. In the method, in the form of a fixed bed separated into 1 to 10 steps, each step is composed of a catalyst layer, a filter, an air inlet, and an outer wall is adiabatic, and the reaction product is continuously passed from top to bottom through a reactor. Circulates in contact with the catalyst layer, heat of vaporization for extracting the produced water is supplied through a heat exchanger outside the reactor, and a reactant is circulated between the reactor and the heat exchanger through a circulation pump, The azeotropic composition of water and alcohol vaporized by the heat exchanger is brought into contact with the alcohol refluxed in the column tower or the raw material alcohol supplied from the alcohol supply port at the top of the column tower to obtain a high boiling point component. The method is characterized in that the light component is refluxed to the reactor, moved to the upper part of the column, liquefied by a condenser, separated into an organic layer and water by a dicant, and then the organic layer is refluxed and produced water is removed. . 2. The method according to claim 1, wherein the unsaturated carboxylic acid is acrylic acid or methacrylic acid. 3. The method of claim 1 wherein the molar ratio of unsaturated carboxylic acid to alcohol is about 1: 0.8-1: 1.3. 4. The method of claim 1, wherein the reaction temperature range is about 70-100 ° C. 5. The method according to claim 1, wherein the reaction pressure is about 50 to 400 (torr). 6. The polymerization inhibitor is in the form of penoliq in an amount of about 100-.
5. Use of about 500 (ppm).
The described method. 7. The amount of alcohol provided for reflux is at least 1 of the amount of alcohol supplied to the esterification reaction.
Method according to claim 1, characterized in that it is 0% by weight. 8. An apparatus for continuously producing unsaturated carboxylic acid esters using a cation exchange resin catalyst in an esterification reaction of an (aliphatic) alcohol having 1 to 8 carbon atoms and an unsaturated carboxylic acid. In the reactor, the reactor (22) is in the form of a fixed bed separated into 1 to 10 stages, and each stage is a catalyst layer (2), a filter (3), an air inlet (4) and an outer wall is adiabatic. Through which the reactant circulates continuously in contact with the catalyst layer from top to bottom, and the heat of vaporization for extracting the produced water is transferred to the heat exchanger outside the reactor (10).
And the azeotropic composition of water and alcohol vaporized by the heat exchanger is refluxed in the column tower (15) by circulating the reactant through the circulation pump (8) between the reactor and the heat exchanger. In contact with alcohol or the raw material alcohol supplied from the alcohol supply port (23) at the top of the column (15), the high boiling point component is refluxed to the reactor, the light component is moved to the upper part of the column and liquefied in the condenser. Zicant (1
After separating the organic layer and water in 8), the organic layer is refluxed to remove produced water.