KR20220071689A - Process for manufacturing acrylic acid - Google Patents

Abstract

The present application relates to a process for manufacturing acrylic acid. The present invention is to provide a process for manufacturing acrylic acid, in which a diluent contains water, and vaporized steam, wherein the diluent includes at least vaporized steam. The present invention includes at least vaporized steam as the dilution solution, so that the residence time required for the dilution process can be reduced, and lactic acid oligomers can be decomposed into lactic acid monomers without additional heat.

Description

The manufacturing process of acrylic acid {PROCESS FOR MANUFACTURING ACRYLIC ACID}

The present application relates to a process for the production of acrylic acid.

In general, acrylic acid is produced through the oxidative dehydrogenation reaction of propylene, and acrylic acid is used as a raw material for super absorbent polymers, paints, adhesives, and the like, and its demand is increasing. In particular, superabsorbent polymers are used in hygiene products such as diapers.

Until now, many of the chemical products have been manufactured using the raw material derived from fossil raw materials, such as coal and petroleum. However, in recent years, from the viewpoint of preventing global warming and protecting the environment, attention has been paid to using recyclable biological resources as a carbon source as a substitute for conventional fossil raw materials. For example, the development of methods using biomass resources such as starch-based biomass such as corn and wheat, carbohydrate-based biomass such as sugar cane, and cellulosic biomass such as rapeseed or rice straw as raw materials has been attempted. have.

In other words, research with excellent characteristics from the point of view of environmental protection while obtaining sustainability by manufacturing chemical products based on eco-friendly raw materials by breaking away from the traditional petrochemical-based manufacturing process is in progress.

As one of the types of reaction for producing other chemical products from lactic acid, there is a gas phase reaction in which a raw material containing lactic acid is evaporated, contacted with a catalyst in a gaseous state, and a product is obtained. For example, a gas-phase dehydration method using a solid catalyst is known as a technology for producing acrylic acid using lactic acid, and research on the dehydration reaction of lactic acid is mainly in progress as a gas-phase reaction.

Lactic acid is a substance that polymerizes while esterification occurs in the liquid phase without a catalyst in the absence of water. As lactic acid is oligomerized and dehydrated, the oligomerization reaction of lactic acid occurs as lactic acid is concentrated without water.

When the lactic acid oligomer is introduced into the reactor for the production of acrylic acid, fouling occurs in the reactor and the reaction yield is lowered. Therefore, a method for reducing the content of the lactic acid oligomer for the production of acrylic acid is being studied.

Among them, in order to lower the content of lactic acid oligomer, it is supplied to the vaporizer in the form of an aqueous lactic acid solution, but water with a low boiling point is vaporized first in the vaporizer and lactic acid is vaporized. is occurring

In addition, it is possible to use a distillation column that separates using the boiling point difference so that the vaporized lactic acid aqueous solution does not contain oligomers. is occurring

Therefore, in order to solve this problem, research is being conducted to lower the content of lactic acid oligomer and increase the yield of acrylic acid produced.

International Publication No. 2005-095320

The present application seeks to provide a process for preparing acrylic acid.

An exemplary embodiment of the present application is a first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material with a diluent; a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized aqueous lactic acid solution; and a third step of including the non-vaporized third aqueous lactic acid solution in the aqueous solution of the first step,

The diluent is water; and vaporized steam, wherein the diluent includes at least vaporized steam.

In the case of the manufacturing process of acrylic acid according to an exemplary embodiment of the present application, in the first aqueous lactic acid solution input to the heat exchanger, during the dilution process for decomposing the lactic acid oligomer, at least vaporized steam as a diluent, The residence time required for the dilution process can be reduced, and the lactic acid oligomer can be decomposed into lactic acid monomers without additional heat (eg, heat exchanger).

In addition, the process for producing acrylic acid according to an exemplary embodiment of the present application includes at least vaporized steam as a diluent, thereby reducing the vaporization capacity of the heat exchanger due to an increase in the temperature of the generated first aqueous lactic acid solution itself. Therefore, it is economical and has the characteristics of producing acrylic acid with a high yield.

1 is a schematic view showing the process of the manufacturing process of acrylic acid according to the present application.
Figure 2 is a schematic diagram showing the process of the manufacturing process of acrylic acid according to Comparative Example 1 of the present application.

Hereinafter, the present specification will be described in more detail.

In the present specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In the present specification, 'p to q' means the range of 'p or more and q or less'.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

An exemplary embodiment of the present application is a first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material with a diluent; a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized aqueous lactic acid solution; and a third step of including the non-vaporized third aqueous lactic acid solution in the aqueous solution of the first step,

The diluent is water; and vaporized steam, wherein the diluent includes at least vaporized steam.

In the case of the acrylic acid production process according to an exemplary embodiment of the present application, in the first aqueous lactic acid aqueous solution in the first step aqueous solution input to the heat exchanger, during the dilution process for decomposing the lactic acid oligomer, at least vaporized steam ( steam), so that the residence time required for the dilution process can be reduced, and the lactic acid oligomer can be decomposed into lactic acid monomers without additional heat (eg, heat exchanger).

In addition, the process for producing acrylic acid according to an exemplary embodiment of the present application includes at least vaporized steam as a diluent, thereby reducing the vaporization capacity of the heat exchanger due to an increase in the temperature of the generated first aqueous lactic acid solution itself. Therefore, it is economical and has the characteristics of producing acrylic acid with a high yield.

In an exemplary embodiment of the present application, a first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material with a diluent is provided.

In an exemplary embodiment of the present application, the lactic acid raw material is water; lactic acid; and lactic acid oligomers.

In the present application, the lactic acid is lactic acid, which is an organic compound having an asymmetric carbon atom bonded to four atomic groups of a carboxy group, a hydroxyl group, a methyl group, and hydrogen, and includes both D-lactic acid and L-lactic acid, and is a single lactic acid monomer. can mean

In the present application, the lactic acid oligomer refers to a material in which lactic acid reacts with each other to form a dimer, a trimer, etc., and the lactic acid oligomer may refer to a dimer to 100mer of lactic acid.

Lactic acid is a substance that polymerizes through an esterification reaction in a liquid phase without a catalyst even in the absence of water. That is, except for a single lactic acid monomer, all substances formed through a polymerization reaction of lactic acid may be defined as lactic acid oligomers.

In an exemplary embodiment of the present application, the diluent is water; and vaporized steam, wherein the diluent may include at least vaporized steam.

In general, the reaction for producing acrylic acid from lactic acid mainly proceeds as a gas phase reaction, and accordingly, a process of vaporizing the aqueous solution of the liquid phase into the gas phase is required.

However, in the case of lactic acid, lactic acid is a substance that forms lactic acid oligomers through esterification in a liquid phase without a catalyst even at room temperature. Since the problem of lactic acid oligomers may occur, a method of reducing the content of lactic acid oligomers as much as possible is being studied.

Since the decomposition rate of lactic acid oligomers into lactic acid monomers proceeds very slowly at a low temperature, the decomposition rate of lactic acid oligomers is very slow at room temperature, thereby increasing the size of the dilution vessel in the dilution process. When the temperature of the dilution vessel is raised to solve the problem of

Accordingly, the process for producing acrylic acid according to the present application includes at least vaporized steam as a diluent in the step of diluting the lactic acid raw material, and efficiently decomposes the lactic acid oligomer within a short time to form a lactic acid monomer. do it with

In an exemplary embodiment of the present application, the first step may include a step of diluting through a dilution vessel.

In particular, as the diluent according to the present application contains at least vaporized steam, the temperature of the first aqueous lactic acid solution itself increases, so that the decomposition rate of the lactic acid oligomer can be increased, and the size of the dilution vessel due to the increase in the decomposition rate can be reduced. and no additional heat source is required.

In an exemplary embodiment of the present application, the dilution vessel internal pressure is 2.0 bar or more and 10.0 bar or less, and the dilution vessel internal temperature is 100° C. or more and 250° C. or less.

In another exemplary embodiment, the internal pressure of the dilution vessel may be 2.0 bar or more and 10.0 bar or less, preferably 2.5 bar or more and 9.5 bar or less, and more preferably 4.0 bar or more and 7.0 bar or less.

As described above, as the internal pressure of the dilution vessel has the above range, the liquid phase of the lactic acid raw material input for dilution can be maintained.

In another exemplary embodiment, the internal temperature of the dilution vessel may be 100°C or more and 250°C or less, preferably 110°C or more and 230°C or less, and more preferably 130°C or more and 200°C or less.

As described above, since the internal temperature of the dilution vessel contains at least vaporized steam as the diluent, the temperature inside the dilution vessel can be maintained within the above range, and thus an additional heat source is not required, so it is economically superior and dilution As the internal temperature of the vessel is formed within the above range, the decomposition rate of the lactic acid oligomer into the lactic acid monomer is excellent.

In an exemplary embodiment of the present application, the amount of heat supplied to the dilute vessel is 0 Gcal/hr to provide a process for producing acrylic acid.

The amount of heat supplied to the dilution vessel may mean the amount of heat supplied from the outside to increase the temperature of the dilution vessel. It has a feature that can be efficiently diluted with the first aqueous lactic acid solution without supply of a separate external heat exchanger.

That is, in the exemplary embodiment of the present application, the first step is a step of diluting with a diluent in the raw lactic acid state, and to minimize the oligomer by increasing the content of water produced during the equilibrium reaction of lactic acid oligomer formation to move the equilibrium reaction It can mean steps. At this time, it is possible to increase the rate of decomposition of the lactic acid oligomer by including at least vaporized steam as the diluent, thereby reducing the size of the dilution vessel and providing no additional heat exchanger supply.

In an exemplary embodiment of the present application, the temperature of the diluted first aqueous lactic acid solution is 100° C. or more and 250° C. or less to provide a process for producing acrylic acid.

In another exemplary embodiment, the first diluted lactic acid aqueous solution may be at a temperature of 100°C or more and 250°C or less, preferably 110°C or more and 230°C or less, and more preferably 130°C or more and 200°C or less.

In the case of the first aqueous lactic acid solution, the temperature of the first aqueous lactic acid solution itself can be maintained in the high temperature range as described above in a diluted state through vaporized steam, and accordingly, when it is supplied to a heat exchanger, which is a subsequent process, The temperature of the first aqueous lactic acid solution satisfies the above range and has a characteristic capable of reducing the vaporization capacity of the heat exchanger.

In an exemplary embodiment of the present application, the first aqueous lactic acid solution refers to the first aqueous lactic acid solution prepared by diluting the lactic acid raw material with a diluent in the first step, and the third aqueous lactic acid solution not vaporized in the heat exchanger to be described later. It may mean an aqueous lactic acid solution that does not contain a liquid circulating flow. That is, the combined aqueous solution of the third aqueous lactic acid solution and the first aqueous lactic acid solution that is not vaporized in the heat exchanger to be described later may be expressed as the aqueous solution of the first step as described above.

In an exemplary embodiment of the present application, the first aqueous lactic acid solution is water; and a lactic acid raw material, wherein the lactic acid raw material is lactic acid; and a lactic acid oligomer, and provides a process for producing acrylic acid including 30 parts by weight or more and 70 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the first aqueous lactic acid solution.

In another exemplary embodiment, based on 100 parts by weight of the first aqueous lactic acid solution, 30 parts by weight or more and 70 parts by weight or less, preferably 35 parts by weight or more and 65 parts by weight or less, more preferably 40 parts by weight or more 55 It may contain up to parts by weight.

In an exemplary embodiment of the present application, the ratio of lactic acid: lactic acid oligomer in the first aqueous lactic acid solution is 80:20 to 95:5 to provide a process for producing acrylic acid.

In another exemplary embodiment, the ratio of lactic acid: lactic acid oligomer in the first aqueous lactic acid solution may satisfy a ratio of 80:20 to 95:5, 85:15 to 93:7, 90:10 to 93:7 .

As described above, the first aqueous lactic acid solution has a high content of lactic acid monomer, and by efficiently decomposing the lactic acid oligomer through the diluent according to the present application, it is possible to increase the yield of acrylic acid in the manufacturing process of acrylic acid in the future, and to supply lactic acid raw material All of the acrylic acid can be formed without waste, so it has excellent economical characteristics.

Specifically, the first step can be confirmed in FIG. 1 , and it can be confirmed that the lactic acid raw material (1) and vaporized steam (7) are input to the dilution vessel 200, and water (2) is included in the dilution step can confirm that it can be done. In addition, the aqueous lactic acid solution after dilution does not include the liquid circulation flow of the third aqueous lactic acid solution 6 that is not vaporized in the heat exchanger 100, which is a step to be described later as the first aqueous lactic acid solution 3, and the first aqueous lactic acid solution 3 And it can be confirmed that the aqueous solution 4 of the first step including all of the third aqueous lactic acid solution 6 that is not vaporized is fed into the heat exchanger 100 .

In the case of the production process of acrylic acid according to the present application, in the case of including a circulation process, the aqueous solution of the first step includes only the first aqueous lactic acid solution in the first steady state, but thereafter, the process of one cycle is performed. In this case, the aqueous solution of the first step may include the first aqueous lactic acid solution and the third aqueous lactic acid solution together.

In an exemplary embodiment of the present application, there is provided a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized lactic acid aqueous solution.

In this case, the second step may include a process of exchanging heat through a heat exchanger.

In an exemplary embodiment of the present application, the heat exchanger is selected from the group consisting of a falling film evaporator, a thin film evaporator, a thermosyphon and a forced circulation evaporator. It may be 1 or more, and if the aqueous solution of the first step can be vaporized, it is not limited thereto.

That is, in the exemplary embodiment of the present application, the second step is a step of vaporizing the aqueous solution of the first step, and the reaction for producing acrylic acid from lactic acid is mainly conducted as a gas phase reaction, and thus the liquid first step It may be a step related to a process of vaporizing the aqueous solution of the step into a gas phase.

In the exemplary embodiment of the present application, as the aqueous solution of the first step is vaporized, the vaporized second lactic acid vapor and the third non-vaporized lactic acid aqueous solution are formed, and the vaporized second lactic acid vapor is a non-vaporized second 3 The content of lactic acid oligomer is maintained lower than that of the aqueous lactic acid solution.

The present application is characterized in that the content of the lactic acid oligomer is maintained low even in the vaporized second lactic acid vapor state by using the diluted first lactic acid aqueous solution having a low content of the lactic acid oligomer.

In the exemplary embodiment of the present application, the third aqueous lactic acid solution that has not been vaporized is included in the aqueous solution of the first step again through the liquid-phase circulation flow in the heat exchanger, so that acrylic acid can be produced without loss of lactic acid raw material will have characteristics.

In an exemplary embodiment of the present application, the internal pressure of the heat exchanger is 0.05 bar or more and 2 bar or less, and the internal temperature of the heat exchanger is 150°C or more and 300°C or less.

In another exemplary embodiment, the internal pressure of the heat exchanger may be 0.05 bar or more and 2.0 bar or less, preferably 0.1 bar or more and 2.0 bar or less, and more preferably 0.5 bar or more and 1.5 bar or less.

In another exemplary embodiment, the internal temperature of the heat exchanger may be 150 °C or higher, preferably 185 °C or higher, more preferably 200 °C or higher, and 300 °C or lower.

By adjusting the pressure of the heat exchanger to the above range, the temperature of the heat exchanger can be properly maintained within the above range, and the pressure difference with the reactor can be reduced later to suitably form the capacity of the compressor for the subsequent process. have possible characteristics. In addition, as the temperature of the heat exchanger is adjusted within the above range, vaporization of the first aqueous lactic acid solution included in the heat exchanger may occur, and decomposition of the lactic acid raw material does not occur, thereby increasing the yield of acrylic acid.

In particular, in the case of the first aqueous lactic acid solution according to the present application, the temperature of the first aqueous lactic acid solution itself can be maintained in the high temperature range as described above in a diluted state through vaporized steam. , the temperature of the first aqueous lactic acid solution contained in the aqueous solution of the first step satisfies the above range, thereby reducing the vaporization capacity of the heat exchanger to form the internal temperature of the heat exchanger.

In an exemplary embodiment of the present application, the amount of heat of the heat exchanger provides a process for producing acrylic acid that is 0.5 Gcal/T or less compared to the amount of vaporization in the heat exchanger.

In an exemplary embodiment of the present application, the second lactic acid vapor is water; and a lactic acid raw material, wherein the lactic acid raw material is lactic acid; and a lactic acid oligomer, and provides a process for producing acrylic acid including 10 parts by weight or more and 80 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the second lactic acid vapor.

In another exemplary embodiment, based on 100 parts by weight of the second lactic acid vapor, 10 parts by weight or more and 80 parts by weight or less, preferably 30 parts by weight or more and 75 parts by weight or less, more preferably 50 parts by weight or more and 60 parts by weight or more It may be less than or equal to parts by weight.

In an exemplary embodiment of the present application, a ratio of lactic acid: lactic acid oligomer in the second lactic acid vapor is 100:0 to 80:20 to provide a process for producing acrylic acid. In this case, the ratio may mean a weight ratio.

In another exemplary embodiment, the ratio of lactic acid:lactic acid oligomer in the second lactic acid vapor is 100:0 to 80:20, preferably 100:0 to 90:10, more preferably 100:0 to 95: 5 can be satisfied.

The second lactic acid vapor is to be included as a reactor of the acrylic acid production process later, and as the ratio of the lactic acid raw material and the lactic acid contained in the lactic acid raw material in the second lactic acid vapor vaporized through the first step satisfies the above range, The amount and amount of water input to the reactor will have suitable characteristics.

In the exemplary embodiment of the present application, the third aqueous lactic acid solution that is not vaporized may be included in the aqueous solution of the first step again through a liquid flow. However, the first aqueous lactic acid solution does not include the non-vaporized third aqueous lactic acid solution. The first aqueous lactic acid solution and the third aqueous lactic acid solution are mixed to form a mixed lactic acid aqueous solution (aqueous solution of the first step), and the mixed aqueous lactic acid solution (aqueous solution of the first step) may be introduced into the heat exchanger.

That is, the third aqueous lactic acid solution that is not vaporized is supplied back to the heat exchanger through the liquid flow, and is used in a different meaning from the first aqueous lactic acid solution in the present application, and the first aqueous lactic acid solution and the third aqueous lactic acid solution are It may mean mixing and input to the heat exchanger according to the present application.

In the case of the third aqueous lactic acid solution, a lactic acid oligomer is formed through an oligomerization reaction of concentrated lactic acid and is recycled without being vaporized. may be included.

Finally, since the process of diluting by adding water to the first aqueous lactic acid solution containing the third aqueous lactic acid solution proceeds, the content of lactic acid oligomers in the lactic acid aqueous solution introduced into the heat exchanger through the equilibrium reaction can be reduced as much as possible.

The production process of the present invention is particularly useful for the synthesis of acrylic acid, and specifically, acrylic acid can be produced by contacting the vapor composition containing lactic acid obtained in the present invention with a dehydration catalyst. The generated reaction gas is collected and liquefied by cooling or contact with a collection liquid, and high-purity acrylic acid can be obtained through a purification process such as extractive distillation and crystallization. The produced acrylic acid is widely used as a raw material for water-absorbing resins, paints, adhesives, and the like.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

< production example >

Examples and comparative examples described below were simulated with Aspen Plus of Aspentech.

If water is diluted to 6T/h in 5T/h of purified lactic acid raw material (85% lactic acid), it becomes 11T/h of lactic acid aqueous solution containing 40% of lactic acid raw material. The lactic acid raw material and water are each put into the dilute vessel, and the lactic acid aqueous solution of the equilibrium composition is put into the heat exchanger with a residence time equal to the time it takes for the oligomers contained in the lactic acid raw material to decompose and become an equilibrium composition.

In the following examples, a portion of the input amount of water was added as steam (11.5 bar, 200° C.), and as a comparative example, water required for dilution was added in a liquid phase of 40° C.

Example One

In the dilution vessel, 5T/h of lactic acid raw material is input, 4.5T/h of water is input, and 1.5T/h of vaporized steam is input. In the dilution vessel, no additional heat is supplied, and the solution in the dilution vessel is maintained at a pressure capable of maintaining the liquid phase without vaporization. Then, the diluted lactic acid raw material was put into a heat exchanger to make lactic acid vapor.

Example 2

In the dilute vessel, 5T/h of lactic acid raw material is input, 4T/h of water is input, and 2T/h of vaporized steam is input. In the dilution vessel, no additional heat is supplied, and the solution in the dilution vessel is maintained at a pressure capable of maintaining the liquid phase without vaporization. Then, the diluted lactic acid raw material was put into a heat exchanger to make lactic acid vapor.

comparative example One

Lactic acid raw material and water were added at 5T/h and 6T/h, respectively, to the dilute vessel, and the residence time was maintained at 40°C until an equilibrium composition was reached. The diluted lactic acid raw material was fed into a heat exchanger to produce lactic acid vapor.

The operation process according to Comparative Example 1 was confirmed in FIG. 2 . Specifically, it was confirmed that 100 parts by weight of water 2 based on 100 parts by weight of the diluent was used without supplying the vaporized steam 7 to the dilution vessel 200, unlike in the above embodiment.

comparative example 2

Lactic acid raw material and water were put into the dilution vessel at 5 T/h and 6 T/h, respectively, and the temperature was raised to 80° C. in the dilution vessel to proceed with oligomer decomposition of lactic acid, and a residence time was maintained until an equilibrium composition was reached. The diluted lactic acid raw material was fed into a heat exchanger to produce lactic acid vapor.

The water input amount, steam input amount, pressure, temperature, heat supply amount, and heat exchanger heat amount used in the diluted vessels according to Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Water input (T/h) 4.5 4 6 6 Steam input (T/h) 1.5 2 0 0 Dilute vessel pressure (bar) 4 7 1.5 1.5 Dilute vessel temperature (°C) 140 170 40 80 Diluted Vessel Feed Calorie (Gcal/hr) 0 0 0 0.4 Heat Exchanger Calorie (Gcal/hr) 4.6 4.3 5.7 5.3

Comparative Example 1 of Table 1 corresponds to the case where the equilibrium reaction occurred at 40° C. without additional heat supply in the dilution vessel, and the residence time in the dilution step is long, so economic feasibility is reduced in the process, and the lactic acid input to the heat exchanger It was confirmed that the content of lactic acid oligomer in the raw material was high, and thus the amount of heat of the heat exchanger was also increased.

Comparative Example 2 of Table 1 corresponds to a case in which the temperature was raised to 80° C. by supplying an additional amount of heat (4 Gcal/h) to the dilution vessel through a separate heat exchanger or jacket in order to reduce the residence time in the dilution vessel. That is, it can be seen that economic efficiency is lowered in that a separate device for supplying an additional amount of heat is required, and compared to the case of supplying steam as in Examples 1 and 2, the temperature of the dilution vessel does not rise and thus the equilibrium reaction is not achieved. It was confirmed that the speed reached was slower than Examples 1 and 2.

In Examples 1 and 2 of Table 1, when vaporized steam is added to the dilution vessel, the temperature of the dilution vessel is maintained at 140° C. and 170° C., respectively, and the speed of reaching the equilibrium reaction is excellent, so the dilution process It was found that it has a characteristic that can minimize the time of

In addition, according to the increased temperature of the diluted vessel, the temperature of the aqueous lactic acid solution input to the heat exchanger also corresponds to a high temperature, so it can be confirmed that the amount of heat in the heat exchanger is also reduced compared to Comparative Examples 1 and 2, and in particular, Comparative Example 1 and In comparison, it was confirmed that the reduction was about 25%.

That is, in the case of the production process of acrylic acid according to the present application, in the first aqueous lactic acid solution input to the heat exchanger, in the dilution process for decomposing the lactic acid oligomer, at least vaporized steam as a diluent is included in the dilution process It was confirmed that the residence time required for the reaction can be reduced, and the lactic acid oligomer can be decomposed into a lactic acid monomer without additional heat (eg, a heat exchanger).

In addition, the process for producing acrylic acid according to an exemplary embodiment of the present application includes at least vaporized steam as a diluent, thereby reducing the vaporization capacity of the heat exchanger due to an increase in the temperature of the generated first aqueous lactic acid solution itself. It was confirmed that it has the characteristics of being economical and capable of producing acrylic acid in high yield.

100: heat exchanger
200: dilution vessel
1: lactic acid raw material
2: water
3: First aqueous lactic acid solution
4: Aqueous solution of the first step (mixed lactic acid aqueous solution)
5: Secondary lactic acid vapor
6: Third aqueous lactic acid solution (liquid cycle)
7: Vaporized Steam

Claims (10)

A first step of preparing a first aqueous lactic acid solution by diluting the lactic acid raw material with a diluent;
a second step of heat exchanging the aqueous solution of the first step to form a second vaporized lactic acid vapor and a third non-vaporized lactic acid aqueous solution; and
a third step of including the non-vaporized third aqueous lactic acid solution in the aqueous solution of the first step;
As a manufacturing process of acrylic acid comprising a,
The diluent is water; and vaporized steam, wherein the diluent contains at least vaporized steam. The method according to claim 1, wherein the first step comprises diluting through a dilution vessel,
The internal pressure of the dilution vessel is 2.0 bar or more and 10.0 bar or less, and the internal temperature of the dilution vessel is 100°C or more and 250°C or less. The process for producing acrylic acid according to claim 2, wherein the amount of heat supplied to the dilute vessel is 0 Gcal/hr. The method according to claim 1, wherein the second step comprises a process of exchanging heat through a heat exchanger,
The internal pressure of the heat exchanger is 0.05 bar or more and 2 bar or less, and the internal temperature of the heat exchanger is 150°C or more and 300°C or less. The process for producing acrylic acid according to claim 4, wherein the amount of heat in the heat exchanger is 0.5 Gcal/T or less compared to the amount of vaporization in the heat exchanger. The process for producing acrylic acid according to claim 1, wherein the temperature of the diluted first aqueous lactic acid solution is 100°C or more and 250°C or less. The process for producing acrylic acid according to claim 1, wherein the amount of the vaporized steam is 1 part by weight or more and 80 parts by weight or less based on 100 parts by weight of the diluent. The method according to claim 1, wherein the second lactic acid vapor is water; and lactic acid raw materials,
The lactic acid raw material is lactic acid; and lactic acid oligomers,
The manufacturing process of acrylic acid comprising 10 parts by weight or more and 80 parts by weight or less of the lactic acid raw material based on 100 parts by weight of the second lactic acid vapor. The process according to claim 1, wherein the ratio of lactic acid to lactic acid oligomer in the second lactic acid vapor is 100:0 to 95:5. The method according to claim 4, wherein the heat exchanger is a falling film evaporator (falling film evaporator), thin film evaporator (wiped film evaporator), thermosyphon (thermosyphon) and forced circulation evaporator (forced circulation evaporator) at least one selected from the group consisting of The manufacturing process of acrylic acid.

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