KR101114400B1 - Process for preparation of 2-ethylhexyl acrylate by batch process - Google Patents

Abstract

The present invention relates to a process for preparing 2-ethylhexyl acrylate by proceeding an esterification reaction of acrylic acid and 2-ethylhexanol in a batch reactor in the presence of a sulfuric acid catalyst and an antipolymerizing agent, and the present invention relates to a case of using a solvent. By replacing the solvent volume with the reactant and replacing most of 2-ethylhexanol, which must be additionally fed to the column, with 2-ethylhexanol used in the reaction, it is possible to secure the volume available for the reaction, There is an increase effect.

2-ethylhexyl acrylate, batch reactor, acrylic acid

Description

Process for preparation of 2-ethylhexyl acrylate by batch process

1 is a process chart showing a method for preparing 2-ethylhexyl acrylate according to the prior art.

2 is a process chart showing a method for preparing 2-ethylhexyl acrylate according to an embodiment of the present invention.

Figure 3 is a graph showing the process conditions of the preparation method of 2-ethylhexyl acrylate according to an embodiment of the present invention.

The present invention relates to a method for producing 2-ethylhexyl acrylate by a batch process, and more particularly, to react acrylic acid (AA) and 2-ethylhexanol (2-EHOH) in a batch reactor, and to generate during the reaction. In the process of separating the water in the column at the top of the reactor to prepare 2-ethylhexyl acrylate,

A first step of introducing a reaction mixture comprising acrylic acid (AA) and 2-ethylhexanol (2-EHOH) corresponding to 2 to 90% of the reactor volume to a batch reactor;

Supplying steam to the batch reactor to initiate a reaction; And

Acrylic acid (AA) was continuously supplied into the reactor, 2-ethylhexanol (2-EHOH) was continuously supplied to the column at the top of the reactor, and the reaction product water was reacted with 2-ethylhexanol (2- Third step to remove in the form of azeotropes of EHOH)

It relates to a method for producing 2-ethylhexyl acrylate comprising a.

The reaction for producing 2-ethylhexyl acrylate by esterifying acrylic acid and 2-ethylhexanol in the presence of a sulfuric acid catalyst is known and is shown in Scheme 1 below.

C ₃ H ₄ O ₂ (AA) + C ₈ H ₁₈ O (2-EHOH) ↔ C ₁₁ H ₂₀ O ₂ (2EHA) + H ₂ O

The reaction is a reversible reaction, in order to increase the conversion of acrylic acid, the equilibrium must be shifted to the right by continuously removing water, the lightest product. At this time, when the water is removed, the next light reactant acrylic acid is followed.

As a method for removing the generated water during the reaction while preventing the entrainment of acrylic acid, the water is removed at an azeotropic temperature lower than the boiling point of the water by using a solvent which forms an azeotropy with water such as benzene, toluene, or xylene and decanter. There is a method of separating only the solvent and refluxing it to the column by using a specific gravity difference separation, but the amount of material to be separated is increased through purification, and at least an amount of solvent corresponding to the azeotropic composition with water must circulate the reactor and the column above the reactor. This is because the energy consumption is a big disadvantage. In addition, some of the reactor volume to be used in the reaction is occupied by the solvent, resulting in less production per batch, and a significant cost in treating wastewater containing harmful solvents.

Another method is to utilize 2-ethylhexanol participating in the reaction as an azeotrope, but the amount of 2-ethylhexanol in the azeotropic composition is not enough to be used for reflux, so that 2- column is used as a column head or decanter. Additional ethylhexanol should be added to increase reflux. In this case, a much larger amount than the amount required for the reaction must be supplied to the column, and since the azeotropic temperature is higher than that of using a separate solvent, there is a disadvantage that a decompression operation must be performed to compensate for this. Particularly in the case of a batch reactor, it is difficult to apply somewhat because the reactor volume is limited.

The present invention is to solve the above problems, the object of the present invention is to solve the problems of increasing the purification column, increased energy consumption, reduced productivity, etc. by using a separate solvent azeotropic with water, It is to provide a method for producing 2-ethylhexyl acrylate that does not use 2-ethylhexanol.

The present invention is a method for producing 2-ethylhexyl acrylate by reacting acrylic acid (AA) and 2-ethylhexanol (2-EHOH) in a batch reactor and separating the produced water in the reaction column in the column of the reactor ,

A first step of introducing a reaction mixture comprising acrylic acid (AA) and 2-ethylhexanol (2-EHOH) corresponding to 2 to 90% of the reactor volume to a batch reactor;

Supplying heat to the batch reactor to initiate a reaction; And

Acrylic acid (AA) was continuously supplied into the reactor, 2-ethylhexanol (2-EHOH) was continuously supplied to the column at the top of the reactor, and the reaction product water was reacted with 2-ethylhexanol (2- Third step to remove in the form of azeotropes of EHOH)

It relates to a method for producing 2-ethylhexyl acrylate comprising a.

The present invention adopts a method of supplying only a part of the reactants acrylic acid and 2-ethylhexanol to the reactor to start the reaction and dividingly supplying the amount necessary for the remaining reaction during the batch time to minimize the amount of acrylic acid present in the reactor and The required 2-ethylhexanol is fed to the top of the column to minimize the amount of acrylic acid that is accompanied by droplets upon water removal. In addition, by sequentially lowering the vacuum degree of the reactor to reduce the amount of acrylic acid entrained in a large amount at the beginning of the reaction.

Hereinafter, each step of the preparation method of 2-ethylhexyl acrylate according to the present invention will be described in detail.

The first step according to the invention is the introduction of a reaction mixture comprising acrylic acid (AA) and 2-ethylhexanol (2-EHOH) corresponding to 2 to 90% of the reactor volume into a batch reactor.

The raw materials introduced into the batch reactor include the reaction mixture, the polymerization inhibitor, and the catalyst. The polymerization inhibitor may be HQ (Hydroquinone), MEHQ (Hydroquinone monomethyl ether), PT (Phenothizaine), CB (Dibutyl dithio carbamic acid copper salt), or P-benzoquinone (PB), the catalyst is sulfuric acid (H ₂ SO ₄ ) or ion-exchange resin may be used, but is not limited thereto.

The reaction mixture introduced into the reactor is preferably a reaction comprising acrylic acid (AA) and 2-ethylhexanol (2-EHOH) corresponding to 5 to 80%, more preferably 10 to 40% of the reactor volume. Mixtures may be introduced. At this time, if the amount of the reaction mixture added is less than 2% of the reactor volume, it is difficult to stir the reaction mixture by the stirrer, so that the reaction does not proceed initially and the batch time increases. There is little 2-ethylhexanol (2-EHOH) which must be continuously supplied to the column, so that the acrylic acid (AA) accompanied by water is increased to increase the loss of reactants.

The second step according to the invention is the step of initiating the reaction by supplying heat to the batch reactor into which the reaction mixture is introduced in the first step. Means for supplying heat to the reactor may be used conventional means, it may be steam or hot oil (hot oil).

In the second step, the reactor temperature is 60 ~ 85 ℃, the pressure is preferably 760 ~ 100 torr. If the reactor temperature of the second stage is less than 60 ℃, the reaction does not proceed, if it exceeds 85 ℃, the amount of acrylic acid (AA) accompanying the splash increases, if the pressure exceeds 760torr, the azeotropic temperature is high, it is difficult to remove water, If it is less than 100torr, the amount of acrylic acid (AA) entrained in the droplets may increase.

In the third stage according to the present invention, acrylic acid (AA) is continuously supplied into the reactor of the second stage, and 2-ethylhexanol (2-EHOH) is continuously supplied to the column at the top of the reactor to generate the reaction. The water is removed in the form of azeotrope of 2-ethylhexanol (2-EHOH).

By dividing the reactants into the reactor as described above, the amount of acrylic acid (AA) present in the reactor may be reduced, thereby minimizing the amount of acrylic acid (AA) accompanied by droplets.

In particular, the third step is

Continuously feeding acrylic acid (AA) and 2-ethylhexanol (2-EHOH) to the reactor and the reactor top column, respectively; And

Blocking acrylic acid (AA) feed to the reactor and feeding only 2-ethylhexanol (2-EHOH) to the reactor top column B)

It is preferable to include.

Step A) is a step for the reaction of acrylic acid (AA) and 2-ethylhexanol (2-EHOH), the reaction of acrylic acid (AA) and 2-ethylhexanol (2-EHOH) 2-ethylhexyl acrylic Rate and water are produced. In addition, as the reaction proceeds, water generated during the reaction is transferred to and removed from the reactor upper column in the form of azeotrope of 2-ethylhexanol (2-EHOH).

Step B) is a step for completing the reaction by reacting the unreacted reactants present in the reactor after step A) and completely removing a small amount of generated water present in the reactor for the next batch. In particular, 2-ethylhexanol (2-EHOH) introduced into the reactor top column in step B) is 2-ethylhexanol (2-EHOH) or reaction which is transferred to the reactor top column in step A) and separated from water. It is preferable to recycle 2-ethylhexanol (2-EHOH) recovered in the purification unit, which is the next step.

In the step A), the weight ratio of the initial acrylic acid (AA) introduced into the reactor in the first step and the acrylic acid (AA) dividedly supplied in the step A) is 1:10 to 10: 1. If the weight ratio is less than 1:10, the reaction rate becomes slow at the beginning of the reaction, and if it exceeds 10: 1, the amount of acrylic acid (AA) to be splashed at the beginning of the reaction increases. In addition, in step A), the weight ratio of initial 2-ethylhexanol (2-EHOH) introduced into the reactor in the first step and 2-ethylhexanol (2-EHOH) supplied in step A) is 1:10. It is preferable that it is-10: 1. When the weight ratio is less than 1:10, the amount of the mixture in the initial reactor is small, making it difficult to stir the reaction mixture and the reaction does not proceed, thereby increasing the batch time. The amount of 2-ethylhexanol (2-EHOH) to be supplied is small, resulting in an increase in the amount of acrylic acid (AA) accompanied by water droplets, thereby increasing the loss of reactants.

Further, in step B), the weight ratio of initial 2-ethylhexanol (2-EHOH) introduced into the reactor in the first step and 2-ethylhexanol (2-EHOH) supplied in step B) is 1: It is preferable that it is 10-10: 1. If the weight ratio is less than 1:10, the amount of acrylic acid (AA) accompanied by splash is increased in step 1, and if the amount exceeds 10: 1, the amount of acrylic acid (AA) is accompanied by splash in step B.

On the other hand, in the method for producing 2-ethylhexyl acrylate according to the present invention, the molar ratio of total acrylic acid (AA) and 2-ethylhexanol (2-EHOH) supplied to the batch reactor is preferably 1: 0.9 to 2.0. Do. If the molar ratio is less than 1: 0.9, the conversion of acrylic acid (AA) is lowered. If the molar ratio is greater than 1: 2.0, the productivity per batch drops to the same level as using a solvent.

In the third step, it is preferable to reduce the reaction pressure from 760 to 100 torr to 350 to 50 torr in order to lower the boiling point of the water removed by the azeotrope. In particular, the decompression rate of step A) is 10 to 100 torr / hr, and the decompression of step B) is a decompression rate of 10 to 100 torr / hr; And it is preferable that the depressurization rate of 30 to 120torr / hr comprises a two-stage decompression step of step b).

When the initial pressure of the reactor is less than 100torr, the azeotropy temperature is too low, so that a large amount of acrylic acid (AA) drops in the initial stage of the reaction. If the final pressure of the reactor exceeds 350 torr, the conversion of the water is not completely removed in the reactor is lowered, if less than 50 torr, the splash of acrylic acid (AA) is increased in the second half of the reaction.

The depressurization step of step A) is a step for azeotropically removing the water produced during the reaction with 2-ethylhexanol (2-EHOH). If the decompression rate is less than 10torr / hr, the water removal rate is slow and the batch time increases. If it exceeds 100torr / hr, the removal rate is faster than the amount of water generated by the reaction, which is accompanied by a drop of acrylic acid (AA), which is the lightest material after the water. In addition, the depressurization step of step B) includes a step a) where the decompression speed is slow and a step b) where the decompression speed is high, but it is not necessary to distinguish them. Step a) is a step for completely removing a small amount of water present in the reactor, step b) is a step for quickly removing all the water generated by the reaction to react even a small amount of unreacted reactant. If the decompression rate of step a) is less than 10 torr / hr, the removal rate of water is slow, so that they remain or the reaction time increases, and if it exceeds 100 torr / hr, the reactant or the product is likely to splash, Is less than 30 torr / hr, the reaction time increases, and if it is more than 120 torr / hr, the reactants or products are likewise splashed, resulting in losses.

The third step reaction according to the present invention is not particularly limited but is preferably carried out at 80 ~ 150 ℃. If the temperature is less than 80 ℃, the reaction does not proceed, if it exceeds 150 ℃ side reactions increase to produce a lot of heavy oil (heavy oil).

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 shows a method for preparing a conventional 2-ethylhexyl acrylate.

According to FIG. 1, a reactant consisting of acrylic acid, 2-ethylhexanol, a polymerization inhibitor, a sulfuric acid catalyst, and benzene is introduced into the reactor RE at about 92% or more of the reactor volume. The product water generated during the reaction is transferred to the upper column (CO-1) in the form of azeotropes with benzene and separated into benzene and water in the decanter (VE-1). The water separated in the decanter (VE-1) is released to the wastewater and benzene is recovered back to the top column (CO-1). Meanwhile, the mixture containing 2-ethylhexyl acrylate as a reaction target material is transferred to a neutralization tank (VE-2) and neutralized with 48% sodium hydroxide. The neutralized mixture is separated into an aqueous layer and an organic layer in an oil / water separation tank (VE-3). Some alcohol and benzene present in the separated aqueous layer are recovered in column (CO-3). In addition, the separated organic layer removes benzene, alcohol, and heavy oil through distillation columns (CO-4, 6, and 7), respectively, to obtain 2-ethylhexyl acrylate as the final target substance. At this time, to remove the salt generated during the neutralization in the rear end of the benzene distillation column (CO-4) is washed with water (CO-5).

2 illustrates a method of preparing 2-ethylhexyl acrylate according to one embodiment of the present invention.

According to FIG. 2, a part of the reactant consisting of acrylic acid, 2-ethylhexanol, a polymerization inhibitor, and a sulfuric acid catalyst is introduced into the reactor RE. According to the present invention, water is removed by forming an azeotrope with 2-ethylhexanol, so that no separate organic matter such as benzene is required, unlike the prior art. When the reaction is initiated a portion of acrylic acid is introduced continuously into the reactor and 2-ethylhexanol is continuously introduced into the top column. The water produced during the reaction is transferred to the upper column (CO-1) in the form of azeotrope with 2-ethylhexanol, and separated into 2-ethylhexanol and water in the decanter (VE-1). After stopping the introduction of acrylic acid into the reactor, 2-ethylhexanol is continuously introduced from the decanter (VE-1) to the top column (CO-1). Meanwhile, the mixture containing 2-ethylhexyl acrylate as a reaction target material is transferred to a neutralization tank (VE-2) and neutralized with 48% sodium hydroxide. The neutralized mixture is separated into an aqueous layer and an organic layer in the oil-water separation tank (VE-3). At this time, since the separated aqueous layer does not contain toxic substances such as benzene, a column (CO-3) for recovering alcohol from the aqueous layer is not necessarily required. The separated oil is washed with water for the purpose of removing the salt used for neutralization (CO-5), and then the alcohol and heavy oil are removed through the distillation columns (CO-6 and 7), respectively. Obtain 2-ethylhexyl acrylate. At this time, since no organic substance such as benzene is used, a separate solvent separation column (CO-4) is not required.

The present invention will be described in more detail with reference to the following Examples. However, the Examples are only for illustrating the present invention and do not limit the present invention to these.

Example 1

The reaction was carried out using a batch reactor (volume: 33m ³ ). After adding the reactant acrylic acid and 2-ethylhexanol to 30% of the reactor volume (AA: 3 ton, 2-EHOH: 5.69 ton), 98% sulfuric acid (163 kg) and PT (Phenothizaine, 28 kg) were used as a polymerization inhibitor. After the addition, while supplying steam to the reactor, the vacuum degree was adjusted to 250torr level. From the time when the reactor temperature reached 75 ° C., acrylic acid (5 ton) and 2-ethylhexanol (10.52 ton) were continuously fed to the reactor and column top, respectively, for 2 hours. At this time, the reaction pressure was adjusted to 200 torr while reducing the pressure at a rate of 25 torr / hr. After 2 hours, the supply of acrylic acid was stopped, and only 2-ethylhexanol (2.41 ton), which was used as refluxed 2-EHOH and 2-EHOH 35%, was continued and the reaction pressure was maintained at a rate of 50 torr / hr. The final pressure was adjusted to 150 torr with reduced pressure. During the reaction time, water was continuously removed to the top of the column in the form of azeotrope with 2-ethylhexanol. Specific reaction conditions are shown in FIG. 3, and the test results are shown in Table 1.

Comparative Example 1

Initially, the amount of acrylic acid and 2-ethylhexanol was supplied to 95% of the reactor volume. The reaction pressure was 760 torr using a benzene solvent, and the water-benzene azeotrope removed from the top of the column was separated from the decanter. The oily phase was carried out in the same manner as in Example 1 except that it was refluxed to the top of the column. The test results are shown in Table 1 and Table 2.

As shown in Table 1, it was confirmed that 2-ethylhexyl acrylate according to the embodiment of the present invention can increase the work yield while maintaining the conversion and selectivity at the same level than the comparative example using benzene.

In a method for producing 2-ethylhexyl acrylate by reacting acrylic acid (AA) and 2-ethylhexanol (2-EHOH) in a batch reactor, and separating the produced water in the column in a column above the reactor. Compared to the case of using a silver solvent, the solvent volume is replaced with the reactant, and the bulk of the 2-ethylhexanol, which has to be additionally supplied to the column, is replaced with the 2-ethylhexanol used in the reaction, thereby ensuring the volume available for the reaction. It is possible to increase production per batch (about 12% increase compared to solvent use).

In addition, since the initial reactant supply amount is short, the raw material supply time can be shortened (12 minutes), and the initial heating time can be shortened (10 minutes). It was possible to shorten the reaction time by maintaining the reaction rate uniformly over time and by utilizing the energy used in the benzene droplets to remove water (30 minutes).

By keeping the initial pressure of the reaction higher than the latter pressure, it is possible to keep the acrylic acid content in the produced water at an existing level even if the amount of 2-ethylhexanol added to the column is minimized by reducing the entrainment of acrylic acid that is easily concentrated at the beginning of the reaction. Could.

Claims (12)

In a method of producing 2-ethylhexyl acrylate by reacting acrylic acid (AA) and 2-ethylhexanol (2-EHOH) in a batch reactor, and generating water in the reaction in a column at the top of the reactor, A first step of introducing a reaction mixture comprising acrylic acid (AA) and 2-ethylhexanol (2-EHOH) corresponding to 2 to 90% of the reactor volume to a batch reactor; Supplying heat to the batch reactor to initiate a reaction; And Acrylic acid (AA) was continuously supplied into the reactor, 2-ethylhexanol (2-EHOH) was continuously supplied to the column at the top of the reactor, and the reaction product water was reacted with 2-ethylhexanol (2- Third step to remove in the form of azeotropes of EHOH) Method for producing 2-ethylhexyl acrylate comprising a. The process of claim 1, wherein the reaction mixture of the first stage introduced into the batch reactor is 5 to 80% of the reactor volume. The method of claim 1, wherein the reactor temperature of the second stage is 60 ~ 85 ℃, the pressure is 760 ~ 100 torr. The method of claim 1 wherein the third step is Continuously feeding acrylic acid (AA) and 2-ethylhexanol (2-EHOH) to the reactor and the reactor top column, respectively; And Blocking acrylic acid (AA) feed to the reactor and feeding only 2-ethylhexanol (2-EHOH) to the reactor top column B) Method for producing 2-ethylhexyl acrylate, characterized in that it comprises a. 5. The 2-ethylhexyl acrylic according to claim 4, wherein the weight ratio of the initial acrylic acid (AA) introduced into the reactor in the first step and the acrylic acid (AA) supplied in the step A) is 1:10 to 10: 1. Method of producing the rate. The weight ratio of initial 2-ethylhexanol (2-EHOH) introduced into the reactor in the first step and 2-ethylhexanol (2-EHOH) supplied in the step A) is 1:10 to 10. It is 1 :, The manufacturing method of 2-ethylhexyl acrylate. The weight ratio of initial 2-ethylhexanol (2-EHOH) introduced into the reactor in the first step and 2-ethylhexanol (2-EHOH) supplied in the step B) is 1:10 to 10. It is 1 :, The manufacturing method of 2-ethylhexyl acrylate. The method of claim 1, wherein the molar ratio of total acrylic acid (AA) and 2-ethylhexanol (2-EHOH) fed to the reactor is 1: 0.9 to 2.0. The method for preparing 2-ethylhexyl acrylate according to claim 1, wherein the reaction pressure of the third step is reduced from 760 to 100 torr to 350 to 50 torr. The method of claim 9, The third step comprises the steps of continuously feeding acrylic acid (AA) and 2-ethylhexanol (2-EHOH) to the reactor and the reactor top column, respectively; And shutting off acrylic acid (AA) feed to the reactor and feeding only 2-ethylhexanol (2-EHOH) to the reactor top column, Method for producing 2-ethylhexyl acrylate, characterized in that the decompression rate of step A) is 10 ~ 100 torr / hr. The method of claim 9, The third step comprises the steps of continuously feeding acrylic acid (AA) and 2-ethylhexanol (2-EHOH) to the reactor and the reactor top column, respectively; And shutting off acrylic acid (AA) feed to the reactor and feeding only 2-ethylhexanol (2-EHOH) to the reactor top column, Decompression of step B) is a step a) with a decompression rate of 10 to 100 torr / hr; And a decompression step of step 2) of step b) having a decompression rate of 30 to 120 torr / hr. The method of claim 1, wherein the third step is carried out at 80 ~ 150 ℃.

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