KR20230097593A - Method for vaporizing lactic acid, and method for preparing acrylic acid from lactic acid - Google Patents

Abstract

This specification relates to a method for vaporizing lactic acid and a method for preparing acrylic acid from lactic acid.

Description

Lactic acid vaporization method and acrylic acid production method {METHOD FOR VAPORIZING LACTIC ACID, AND METHOD FOR PREPARING ACRYLIC ACID FROM LACTIC ACID}

This specification relates to a method for vaporizing lactic acid and a method for producing acrylic acid from lactic acid.

Lactic acid, also called lactic acid or lactic acid, is an organic acid with a relatively simple structure that contains both a hydroxy group and a carboxyl group in its molecule.

Lactic acid has traditionally been naturally produced in the fermentation process of lactose or glucose, and has served to improve the flavor of fermented foods. It has been variously used in the cosmetic field, such as a skin whitening agent, or in the medical field, such as an intravenous solution, dialysis solution, and calcium agent.

Recently, lactic acid polymers and polylactides are biodegradable, and interest is increasing as eco-friendly alternative polymers that can replace plastics that are not naturally degradable, such as polyolefins, polystyrene, and polyesters produced from petroleum. It is also receiving high attention as a precursor of acrylic acid, which is regarded as very important in terms of its chemical properties.

Lactic acid can be mainly produced by microbial fermentation or chemical synthesis. Recently, starch-based biomass such as corn, sugar-based biomass such as sugar cane, or cellulose-based biomass obtained from woody or herbaceous plants, etc. Methods for producing lactic acid using biomass resources as raw materials are being studied.

Lactic acid obtained in this way is usually concentrated and stored at a high concentration during storage or distribution after production. Alternatively, in many cases, water molecules are removed to form oligomers in the form of dehydration condensation.

A large amount of lactic acid is lost due to dimerization or oligomerization, and oligomerized lactic acid increases the amount of by-products generated in a chemical reaction using lactic acid and forms coking during the reaction, greatly reducing the efficiency of the reaction. there is

In particular, in the lactic acid vaporization reaction, when the lactic acid aqueous solution is heated to vaporize lactic acid, water with high vaporization efficiency is vaporized first rather than lactic acid with low vaporization efficiency. and, accordingly, the concentration of oligomers in the aqueous solution of lactic acid also increases.

In the present specification, in the lactic acid vaporization reaction, the content of oligomers in the lactic acid vaporized product can be reduced to increase the recovery rate and vaporization efficiency, while suppressing the production of by-products such as acetaldehyde that can be generated in the vaporization process. It is intended to provide a method for vaporizing lactic acid.

In addition, the present specification is intended to provide a method for producing acrylic acid from the vaporized lactic acid.

The present specification, a first step of supplying an aqueous lactic acid solution to the vaporization reactor; a second step of heating the lactic acid aqueous solution in a vaporization reactor to obtain a gaseous first stream containing lactic acid molecules and lactic acid oligomer molecules; and a third step of heating the vaporization reactor while supplying a gas containing oxygen to remove a small amount of residue generated in the vaporization reactor in the second step.

According to one embodiment of the invention, the first step may be to supply an aqueous solution of lactic acid as a raw material for the vaporization reaction after diluting the lactic acid raw material in water.

And, in the first step, the lactic acid aqueous solution supplied to the vaporization reactor may be about 30 to about 70 wt%. That is, the aqueous solution of lactic acid may be concentrated to a certain concentration and contain a certain amount of oligomers by equilibrium.

According to one embodiment of the invention, the temperature of the lactic acid aqueous solution supplied to the reactor may be about 15 °C to about 90 °C.

According to one embodiment of the invention, the second step may be performed at a temperature condition of about 250 °C to about 400 °C.

In addition, the entire process may be carried out in a batch or continuous manner.

According to one embodiment of the present invention, the vaporization method is a first step of conveying and cooling the gaseous first stream generated in the second step, and separating gaseous lactic acid monomolecules and liquid lactic acid oligomers through gas-liquid separation. It may include 4 more steps.

According to one embodiment of the invention, the fourth step may be performed at a temperature condition of about 150 °C to about 300 °C.

According to one embodiment of the present invention, the liquid lactic acid oligomer separated in the fourth step may be diluted in water and recycled as a raw material for vaporizing an aqueous lactic acid solution.

According to another embodiment of the invention, it may be preferable that the third step is performed under a gas supply containing oxygen at a temperature condition of about 300 ° C to about 600 ° C.

And, when the gas is supplied, the oxygen content may be about 1 to about 20%.

On the other hand, the present specification, vaporizing lactic acid according to any one of the above methods to obtain a single molecule of lactic acid in the gas phase; and dehydrating the lactic acid molecule to produce acrylic acid.

In the present invention, terms such as first and second are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

In addition, terms used in this specification are only used to describe exemplary embodiments, and are not intended to limit the present invention.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as "comprise", "comprise" or "having" are used to describe an implemented feature, number, step, component, or combination thereof, and one or more other features, numbers, or steps. , components, combinations or additions thereof are not excluded.

Also, in this specification, when each layer or element is referred to as being formed “on” or “above” each layer or element, it means that each layer or element is formed directly on each layer or element, or other This means that layers or elements may be additionally formed between each layer or on the object or substrate.

Since the present invention can have various changes and various forms, specific embodiments will be exemplified and described in detail below. However, it should be understood that this does not limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention.

In the present specification, lactic acid is a compound represented by the following chemical formula, and is used as a concept encompassing all lactic acid isomers, naturally occurring lactic acid dimers, and lactic acid oligomers, unless otherwise stated herein.

Hereinafter, the present invention will be described in detail.

According to one aspect of the present specification, a first step of supplying an aqueous lactic acid solution to a vaporization reactor; a second step of heating the lactic acid aqueous solution in a vaporization reactor to obtain a gaseous first stream containing lactic acid molecules and lactic acid oligomer molecules; and a third step of heating the vaporization reactor while supplying a gas containing oxygen to remove a small amount of residue generated in the vaporization reactor in the second step.

The inventors of the present invention, in a method of heating and vaporizing an aqueous lactic acid solution and obtaining lactic acid gas molecules, heat the aqueous lactic acid solution introduced into the vaporization reactor to obtain a gaseous mixture, and in the vaporization process, a trace amount that may occur inside the reactor The present invention was completed by finding that it is possible to prevent clogging of tubes in the reactor by removing the residue of from the reactor through heating under changed weather conditions.

Lactic acid is widely used in the production of acrylic acid. When producing acrylic acid by dehydrating lactic acid, it is necessary to vaporize lactic acid into lactic acid molecules because it proceeds by a gas phase reaction.

However, as described above, lactic acid is usually stored at a high concentration during storage or distribution after production. In many cases, a dimer structure is formed, or an oligomer in the form of dehydration condensation is formed by removing water molecules.

These lactic acid oligomer molecules are carbonized in the vaporization step or reaction step to form coking, which can reduce the active area of the reaction catalyst, and can also be included in lactic acid, which is a product of the vaporization reaction, as a by-product. Therefore, the content of monomolecular lactic acid that can participate in the reaction is greatly reduced, thereby reducing the vaporization efficiency.

Therefore, when lactic acid is vaporized, the concentrated lactic acid aqueous solution containing a high content of lactic acid oligomer is diluted with distilled water or the like, and is often used after converting to a low concentration.

However, even when the aqueous solution of lactic acid is diluted to a low concentration to lower the content of oligomers and vaporizes them, since the vaporization efficiency of lactic acid is lower than that of water, water vaporizes first, and the proportion of vaporized lactic acid is about 20 wt%. will fall short of In this case, as water vaporizes first, the concentration of the remaining lactic acid aqueous solution further increases, and accordingly, the concentration of oligomers in the remaining aqueous lactic acid solution further increases. In addition, in this process, the oligomers, etc. There is a problem in that it remains in the form of a residue and can cause tube blockage.

Therefore, in the lactic acid vaporization method according to an embodiment of the present invention, the aqueous lactic acid solution introduced into the vaporization reactor is quickly heated before the oligomer concentration increases to obtain a gaseous mixture, and the obtained gaseous mixture is transferred through a separate transfer line. In the process of vaporizing the lactic acid aqueous solution introduced into the reactor, some unvaporized residues are removed by heating under oxygen supply conditions.

Through this separate heating process, the residue remaining inside the vaporization reactor can be removed to prevent clogging of the tube, and the residue or the lactic acid oligomer contained in the residue is mixed in the aqueous lactic acid solution to be added later. problems can be avoided.

According to one embodiment of the invention, the first step may be to add water to dilute the lactic acid raw material and then supply an aqueous lactic acid solution as a raw material for the vaporization reaction.

In addition, when supplying the lactic acid aqueous solution into the lactic acid reactor, a separate transfer gas may be used.

That is, when the aqueous lactic acid solution, which is a raw material of the vaporization reaction, is introduced into the vaporization reactor, the highly concentrated aqueous solution of lactic acid may be directly introduced as described above, or diluted with distilled water to lower the concentration of lactic acid as described above. .

And, in the first step, the lactic acid aqueous solution supplied to the vaporization reactor may be about 30 to about 70 wt%. That is, the aqueous solution of lactic acid may be concentrated to a certain concentration and contain a certain amount of oligomers by equilibrium.

This corresponds to the general concentration of commercially available lactic acid raw materials, such as production, storage, distribution, and sales of lactic acid, or the concentration of diluting the commercially available lactic acid raw materials in distilled water or the like to be introduced into the vaporization reaction.

Here, the aqueous solution of lactic acid introduced into the reactor means a state in which lactic acid is dissolved in water, and as described above, it naturally includes all lactic acid monomolecules, lactic acid dimers, and lactic acid oligomers depending on the temperature and concentration conditions. .

In addition, the concentration of lactic acid described herein also means the concentration of not only a single molecule of lactic acid, but also a single molecule of lactic acid, a lactic acid dimer, and a lactic acid-based compound including all of the lactic acid oligomers.

More specifically, for example, when calculated by computer modeling, the content of oligomers by concentration of all lactic acid-based compounds in an equilibrium state is shown in Table 1 below.

However, this may cause slight calculation errors depending on the actual calculation model, and actual measured values may also have slight measurement errors depending on measurement conditions or measurement methods (titration method or HPLC).

Monomer reduction concentration of total lactic acid compounds
(wt%) monomolecular concentration
(wt%) dimer concentration
(wt%) Trimeric Concentration
(wt%) 5 5.0 0.019 0.001 10 9.9 0.079 0.011 15 14.8 0.187 0.013 20 19.6 0.35 0.05 25 24.3 0.575 0.125 30 29.0 0.874 0.126 35 33.6 1.26 0.14 40 38.0 1.75 0.25 45 42.3 2.35 0.35 50 46.3 3.11 0.59 55 50.2 4.03 0.77 60 53.8 5.18 1.02 65 56.9 6.58 1.52 70 59.6 8.31 2.09 75 61.5 10.4 3.1 80 62.5 13.0 4.5 85 62.2 16.2 6.6 90 60.1 19.8 10.1 95 55.4 23.6 16 100 47.6 26.6 25.8

In the general lactic acid vaporization reaction, the concentration of oligomers is often increased by about two times during the vaporization process due to the aforementioned difference in vaporization efficiency between water and lactic acid or problems such as concentration.

However, in the case of the method according to one embodiment of the present invention, even if the content of lactic acid oligomers in the lactic acid mixture decreases or the content of oligomers increases, since the oligomers can be separated through a separate process, a single molecule of lactic acid in high yield. can be obtained, and lactic acid-type compounds lost in the form of oligomers are recovered in the liquid phase and reused, thereby greatly reducing the ratio of lost lactic acid.

Specifically, in the method according to an embodiment of the present invention, the change rate of the oligomer content represented by Equation 1 below is 10% or less, or about 5% or less.

Equation 1

In Equation 1 above,

OC1 is the content (wt%) of lactic acid oligomers relative to the total weight of lactic acid single molecules and lactic acid oligomers in the lactic acid aqueous solution supplied to the reactor,

OC2 is the content (wt%) of lactic acid oligomers relative to the total weight of lactic acid single molecules and lactic acid oligomers in the lactic acid gas vaporized by the above method.

According to one embodiment of the invention, the temperature of the lactic acid aqueous solution supplied to the reactor may be about 15 °C to about 90 °C.

If the temperature of the supplied lactic acid aqueous solution is too low, it may take a long time to obtain energy required for vaporization after lactic acid is added to the reactor, and if the temperature of the supplied lactic acid aqueous solution is too high, the pressure inside the reactor This excessively high problem may occur.

According to one embodiment of the invention, the second step may be performed at a temperature condition of about 250 °C to about 400 °C. If the temperature of the second step, that is, the step of heating the lactic acid aqueous solution in the vaporization reactor to obtain a gaseous first stream containing lactic acid molecules and lactic acid oligomer molecules, is too low, the heat exchange efficiency is lowered, resulting in the amount of lactic acid oligomers produced. This increasing problem may occur, and when the temperature of the vaporizing unit is too high, lactic acid is decomposed and by-products may be generated.

In addition, the entire process may be carried out in a batch or continuous manner.

In addition, it may be preferable that the supplied lactic acid aqueous solution is vaporized almost entirely at about 95 wt% or more, or about 99 wt% or more inside the vaporization reactor. When the lactic acid aqueous solution for vaporization is continuously supplied and the vaporization proceeds only to the extent that a part of the lactic acid aqueous solution supplied into the vaporization reactor is not completely vaporized, but only a part of the lactic acid aqueous solution is supplied to the vaporization reactor, there is a problem in that the amount of lactic acid oligomer is excessively generated, and the increased lactic acid oligomer There may be a problem in that additional energy loss occurs to convert lactic acid into single molecules later.

However, in the vaporization process, some of the materials to be vaporized are not vaporized, and thus carbon residues may remain on the walls of the reactor, and tube blockage may be caused by these residues during long-term operation.

Therefore, in the vaporization method according to an embodiment of the present invention, the first step and the second step each proceed in a continuous manner to obtain a vaporized mixture generated according to the vaporization reaction, that is, the first stream, and the tube blockage problem In order to prevent or solve the problem, residues generated in the vaporization reaction are removed through a separate third step.

According to one embodiment of the present invention, the vaporization method is a first step of conveying and cooling the gaseous first stream generated in the second step, and separating gaseous lactic acid monomolecules and liquid lactic acid oligomers through gas-liquid separation. It may include 4 more steps.

When the obtained gaseous mixture is transferred and then cooled, gaseous lactic acid single molecules and liquid lactic acid oligomers can be separated, thereby reducing the lactic acid oligomer content in the vaporized lactic acid compound and increasing the lactic acid single molecule content, During the vaporization process, the generation of by-products such as acetaldehyde can be suppressed.

In addition, through such a separate gas-liquid separation process, it is possible to reduce the content of lactic acid oligomers in vaporized lactic acid compounds and increase the content of single molecules of lactic acid, while suppressing the generation of by-products such as acetaldehyde in the vaporization process. In addition, the separated liquid lactic acid oligomer can be reused as a reactant of the vaporization reaction through a separate treatment.

According to one embodiment of the invention, the fourth step may be performed at a temperature condition of about 150 °C to about 300 °C. If the temperature of the fourth step, that is, the gas-liquid separation step is too low, even a single molecule of lactic acid contained in the second stream may be liquefied, resulting in a significant decrease in vaporization efficiency. If it is too high, gas-liquid separation may not be completely achieved, resulting in a high content of lactic acid oligomers in the final product.

And, according to another embodiment of the invention, the liquid lactic acid oligomer separated in the fourth step can be diluted in water and recycled as a raw material for vaporization of the lactic acid aqueous solution. More specifically, as described above, in the method according to an embodiment of the present invention, the first to second steps are performed continuously. Therefore, the liquid lactic acid oligomer separated in the above gas-liquid separation step, that is, the fourth step, is diluted with water to achieve concentration equilibrium between the lactic acid single molecule and the lactic acid oligomer, and is then continuously put back into the vaporization reaction for reuse. can do.

1 is a process chart schematically showing a method according to an embodiment of the present invention.

Referring to FIG. 1 , in the lactic acid vaporization method according to one aspect of the present specification, a first step of supplying an aqueous lactic acid solution 12 to a vaporization reactor 210; A second step of heating the lactic acid aqueous solution in the vaporization reactor 210 to obtain a gaseous first stream 2 containing lactic acid molecules and lactic acid oligomer molecules; and a third step of heating the gasification reactor under a gas supply 110 containing oxygen to remove a small amount of residue generated in the gasification reactor in the second step.

In addition, the gaseous first stream 2 generated in the second step is transported and cooled, and gaseous lactic acid single molecules (3-1) and liquid lactic acid oligomers (3-2) are obtained through gas-liquid separation. In the fourth step of separation, it can be confirmed that the liquid lactic acid oligomer (3-2) separated in the fourth step is recycled as a raw material for the aqueous lactic acid solution for vaporization.

On the other hand, the present specification, vaporizing lactic acid according to any of the above methods to obtain a single molecule of lactic acid in the gas phase; and dehydrating the lactic acid molecule to produce acrylic acid.

The reaction for producing acrylic acid by intramolecular dehydration of lactic acid can be represented by the following chemical formula, and is known to proceed in one step in the presence of a catalyst.

However, in the case of the acrylic acid production method according to one aspect of the present invention, except for the above-mentioned lactic acid vaporization, in relation to the method for producing acrylic acid from vaporized lactic acid, generally known in the art to which the present invention belongs Catalysts, reactors, or reaction conditions may be employed.

For example, the catalyst used in the lactic acid dehydration reaction is CaSO ₄ / Na ₂ SO ₄ ; Na ₄ P ₂ O ₇ /CaSO ₄ ; Na ₄ P ₂ O ₇ /Ca ₃ (PO ₄ ) ₂ ; NaH ₂ PO ₄ -NaHCO ₃ /SiO ₂ ; AlPO ₄ -NH ₃ ; Ca ₃ (PO ₄ ) ₂ /CaSO ₄ and the like are exemplified.

The dehydration reaction using a solid catalyst may proceed as a continuous reaction using a stationary reactor or a batch reaction. In the case of using a stationary reactor, products can be continuously produced by filling the reactor with a solid catalyst and continuously supplying reactants to the reactor for reaction.

The temperature of the dehydration reaction may be about 300 to about 500 °C, or about 300 to about 400 °C. The reaction pressure may be between about 1 atmosphere and about 5 atmospheres, or between about 1 atmosphere and about 2 atmospheres.

The supply rate of the reactant may vary depending on the type or type of the reactor, other reaction conditions, etc., but specifically, for example, the weight hourly space velocity (WHSV) of the gas phase is about 0.05 to about 1.0 / hr, or about 0.10 to about 0.50/hr.

When the above conditions are out of the range, a decomposition reaction by hydrogenation proceeds, resulting in a decrease in reaction efficiency or a decrease in conversion rate.

1 is a process chart schematically showing a method according to one aspect of the present invention.

Referring to FIG. 1, lactic acid is vaporized to obtain a single molecule of lactic acid in the vapor phase (3-1), and the single molecule of lactic acid (3-1) is introduced into a dehydration reactor 310 for a dehydration reaction to obtain acrylic acid 330. You can check the steps to get it.

According to the lactic acid vaporization method according to one aspect of the present invention, the content of lactic acid oligomers in the obtained product can be reduced and the content of single molecules of lactic acid can be increased, while the generation of side reactants can be suppressed.

1 is a process chart schematically showing a method according to one aspect of the present invention.

Hereinafter, the action and effect of the invention will be described in more detail through specific examples of the invention. However, these embodiments are only presented as examples of the invention, and the scope of the invention is not determined thereby.

<Example>

As a raw material for lactic acid, an 88 wt % aqueous solution of lactic acid (trade name: PURAC HS88, manufactured by Corbion) was prepared.

About 1075 g of the prepared lactic acid raw material and a certain amount of distilled water are mixed, and refluxed at a temperature of about 95 ° C. for about 18 hours to obtain an aqueous solution of lactic acid at a specific concentration in which lactic acid and lactic acid oligomers reach an equilibrium state, which is subjected to a lactic acid vaporization reaction It was used as a feed for

As a vaporization reactor for the vaporization reaction, a single reaction tube made of Hastelloy material having a diameter of 1 inch was used. The inside of the vaporization reactor was filled with quartz sand to increase heat exchange efficiency.

The feed for the lactic acid vaporization reaction, that is, the lactic acid aqueous solution, was introduced into the vaporization reactor at a flow rate of about 0.5 mL/h, and the vaporization reaction was conducted at 330 ° C for 72 hours, confirming that all of the lactic acid aqueous solution introduced into the reactor was vaporized. did

In addition, a gas transfer line made of SUS316 was placed at the bottom of the lower portion of the vaporization reactor so that vaporized lactic acid could be discharged, and the temperature of the transfer line was set to about 250 °C.

At the other end of the gas transfer line, a condenser at about 200 ° C. was installed to separate gaseous lactic acid single molecules and gaseous lactic acid oligomers from the vaporized lactic acid mixture, thereby separating lactic acid oligomers and gaseous lactic acid single molecules.

The obtained single molecule of lactic acid was transported through a separate transfer line, and a condenser at about 4 ° C was also installed there, so that the amount of single molecule of lactic acid obtained could be confirmed.

After the vaporization experiment was performed, the temperature of the vaporization reactor was heated to about 450° C. while supplying a gas containing oxygen at a concentration of about 10 vol% to the inside of the vaporization reactor to remove residues in the vaporization reactor. In the above example, when the experiment was performed without removing the residue, the tube was blocked after about 800 hours and the pressure gradually increased, and it was confirmed that oligomers were additionally generated in the vaporization reaction.

The concentration of the lactic acid aqueous solution was quantitatively analyzed using HPLC, and the analysis results are summarized in the table below.

HPLC analysis conditions

The sample was filtered with a syringe filter (pore size: 450 ㎛, PVDF membrane), diluted 40 times with water, and then subjected to HPLC analysis under the following conditions.

Manufacturer: Agilent; Model Name: 1260 Infinity II; Column: Aminex HPX-87H; Eluent: 0.5 mM H ₂ SO ₄ aqueous solution; Flow rate: 0.4 ml/min; Injection amount: 10 µl; Detection: DAD detector, 210nm, 230nm, 250nm, 270nm

Supply feed concentration (wt%) Vaporization reactor temperature (℃) Recovery rate (wt%) Oligomer content change rate (%) Feed concentration after vaporization (wt%) Monomer composition (wt%) Dimer composition (wt%) Acetaldehyde (wt%) Others (wt%) 40 200 80.5 323.3 18.7 79.1 20.7 - 0.2 40 250 95.7 210.8 35.1 84.6 15.2 - 0.2 40 300 100.3 88.5 40.1 90.4 9.2 0.3 0.1 40 350 99.2 62.7 39.9 91.2 7.9 0.7 0.2 40 400 97.9 56.0 38.5 88.2 7.3 3.1 1.4 40 450 88.9 50.2 31.1 73.0 5.8 17.0 4.2

Recovery rate according to vaporization reactor temperature and composition of vaporized feed. When the temperature of the vaporization reactor is low, the oligomer content change rate increases and the input feed is not all vaporized, resulting in a decrease in recovery rate.

Supply feed concentration (wt%) Vaporization reactor temperature (℃) Gas-liquid separator temperature Recovery rate (wt%) Oligomer content change rate (%) Feed concentration after vaporization (wt%) Monomer composition (wt%) Dimer composition (wt%) Acetaldehyde (wt%) Others (wt%) 50 350 170 58.4 -9.1 14 92.7 6.3 0.3 0.7 50 350 300 100.1 71.4 50.2 87.3 11.9 0.6 0.2 70 350 180 42.7 -10.3 28.8 86.4 12.1 0.5 One 70 350 220 59.2 -4.3 51.6 84.2 12.7 0.6 2.5 70 350 260 82.9 54.4 63.8 77.9 20.9 0.8 0.4

Meanwhile, the oligomer content change rate may be controlled by controlling the temperature of the gas-liquid separator.

110: oxygen supplier; 120: aqueous solution of lactic acid;
210 vaporization reactor; 220: gas-liquid separator
2: first stream
3-1: single molecule of lactic acid in the vapor phase; 3-2: liquid lactic acid oligomer
310: dehydration reactor; 320: lactic acid single molecule; 330: acrylic acid
420: lactic acid raw material; 410: water;
111, 121, 311, 321, 411: flow control valve

Claims (10)

A first step of supplying an aqueous lactic acid solution to the vaporization reactor;
a second step of heating the lactic acid aqueous solution in a vaporization reactor to obtain a gaseous first stream containing lactic acid molecules and lactic acid oligomer molecules; and
A third step of heating the vaporization reactor under supply of a gas containing oxygen to remove a trace amount of residue generated in the vaporization reactor in the second step,
Lactic acid vaporization method.
According to claim 1,
In the first step, after diluting the lactic acid raw material in water, an aqueous lactic acid solution is supplied as a raw material for the vaporization reaction.
According to claim 1,
In the first step, the lactic acid aqueous solution supplied to the vaporization reactor is 30 to 70 wt%, lactic acid vaporization method.
According to claim 1,
The temperature of the lactic acid aqueous solution supplied to the reactor is 15 ° C to 90 ° C, a method for vaporizing lactic acid.
According to claim 1,
The second step is carried out at a temperature condition of 250 ℃ to 400 ℃, lactic acid vaporization method.
According to claim 1,
The third step is carried out under the supply of a gas containing oxygen at a temperature of 300 ° C to 600 ° C, a method of vaporizing lactic acid.
According to claim 1,
A method for vaporizing lactic acid, further comprising a fourth step of transporting and cooling the first gaseous stream generated in the second step, and separating gaseous lactic acid single molecules and liquid lactic acid oligomers through gas-liquid separation.
According to claim 7,
The fourth step is carried out at a temperature condition of 150 ℃ to 300 ℃, lactic acid vaporization method.
According to claim 7,
A method for vaporizing lactic acid in which the liquid lactic acid oligomer separated in the fourth step is diluted with water and recycled as a raw material for an aqueous lactic acid solution for vaporization.
vaporizing lactic acid according to the method according to any one of claims 1 to 9 to obtain a single molecule of lactic acid in the gas phase; and
A method for producing acrylic acid comprising the step of producing acrylic acid by dehydrating the lactic acid molecule.

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