Method for purifying light alkyl acrylates

Abstract

The present invention relates to the production of light (meth)acrylic acid esters, such as methyl or ethyl (meth)acrylate, by direct esterification of (meth)acrylic acid with a corresponding light alcohol. More specifically, the present invention relates to a method for the recovery / purification of C1-C2 alkyl acrylates, which includes a hydrolysis step that enables the conversion of Michael adducts into acidic products having boiling points very different from those of acrylic acid, and thus simplifies the purification sequence.

Description

Technical Field

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[0001] The present invention relates to the production of light (meth)acrylic acid esters such as methyl or ethyl (meth)acrylate by direct esterification of (meth)acrylic acid with the corresponding light alcohol.

[0002] More specifically, the present invention relates to a method for the recovery / purification of C1-C2 alkyl acrylates that includes an acidolysis step that enables the conversion of Michael adducts into acidic products having a boiling point much higher than that of acrylic acid, and thus simplifies the purification sequence.

Background Art

[0003] <000001?It is known to produce (meth)acrylic acid esters by performing an esterification reaction between an alcohol and (meth)acrylic acid. This reaction is an equilibrium catalytic reaction accompanied by the production of water. Side reactions that produce impurities also occur. <?

[0004] It is necessary to remove the water produced in order to shift the equilibrium, remove impurities, and recycle unreacted reactants.

[0005] For this purpose, sets of distillation and / or extraction, separation by precipitation are generally carried out, which are relatively complicated to implement, especially as a result of the presence of azeotropic mixtures, and are also costly in terms of energy.

[0006] Next, problems that occur during the production of light (meth)acrylic acid esters, particularly C1-C2 alkyl acrylates, will be described for the sake of convenience based on the example of methyl acrylate obtained by esterification of acrylic acid and methanol. However, the problems and the solutions proposed by the present invention can be applied to the use of ethanol in the esterification reaction.

[0007] It should be noted that there seems to be an unclear "?000001?" in the original text at line 15 which is translated as "<000001?". You may want to check and correct this if it's an error in the original.As a side reaction during the production of methyl acrylate, unreacted acrylic acid may form oligomers such as 3-acryloyloxypropionic acid (n=2) or 3-acryloyloxy-3-propoxypropionic acid (n=3), which are heavy by-products with boiling points higher than those of acrylic acid.

[0008] As another side reaction, Michael addition may produce Michael adducts, and in particular, Michael addition between an already formed methyl acrylate and methanol results in the formation of methyl methoxypropionate.

[0009] Methyl methoxypropionate (MMP) is a "heavy" byproduct because its boiling point (142°C at atmospheric pressure) is significantly higher than that of the resulting methyl acrylate (80°C at atmospheric pressure). It is formed in considerable quantities along with the acrylic acid oligomer as the esterification reaction progresses.

[0010] Methyl methoxypropionate poses a problem because it exhibits a vapor pressure close to that of acrylic acid. Its boiling point is also close to that of acrylic acid (144°C at atmospheric pressure), and it can form an azeotrope with water. It is concentrated mainly in the recirculation loop of unreacted acrylic acid. This recirculation loop then needs to be purged, which can result in a significant loss of acrylic acid. Furthermore, since MMP is the lightest of the heavy byproducts compared to acrylic acid oligomers, it can hinder the final purification of methyl acrylate and negatively affect the quality of the final product.

[0011] To limit the formation of methyl methoxypropionate, reference US6025520 proposed carrying out the esterification reaction under reduced pressure with an excess of acid. These conditions improve the yield and selectivity of the esterification reaction and significantly reduce the formation of heavy byproducts such as methyl methoxypropionate, which are problematic in the sequence for purifying the desired ester, due to the addition of methanol.

[0012] The method described in reference WO2015 / 063388 proposes a significant reduction in the formation of alkylalkoxypropionates during the synthesis of methyl or ethyl (meth)acrylates in conventional fixed-bed reactor techniques by carrying out the esterification reaction under atmospheric pressure under conditions where the acid is in excess relative to the alcohol and the space velocity per hour is high.

[0013] The method described in reference US2001 / 0047106 proposes converting the oxyester produced during esterification by catalytic decomposition at high temperatures (150-250°C) with the addition of acrylic acid and water. In this case, the formed product is mainly an ester, and the addition of water allows for the limiting of olefin and ether formation at high temperatures. However, this type of reaction requires a lot of energy to reach this temperature level.

[0014] In their patent FR3083233, the applicant's company demonstrated that methyl methoxypropionate can be partially removed by side-flow extraction during azeotropic distillation of a reaction mixture carried out in a single distillation column equipped with side-flow extraction. This invention makes it possible to remove MMP / water azeotrope without affecting the MMP in the flow, which is mainly composed of acrylic acid and present at the bottom of the azeotropic column.

[0015] However, the need to remove methyl methoxypropionate formed during the synthesis of methyl acrylate still exists, which negatively impacts the mass balance of the method (loss of starting material during purging) and the purification sequence (complexity required to achieve high purity).

[0016] Surprisingly, the inventors discovered that the Michael adduct formed by this method can be efficiently removed by acid decomposition, which converts the Michael adduct into a high-boiling point acid and then removes it at the bottom of the cracker, thereby removing methyl methoxypropionate (or ethyl methoxypropionate) and obtaining high-purity methyl acrylate (or ethyl acrylate). Thus, the alkyl ester stream can be purified and recycled back into the reaction. [Prior art documents] [Patent Documents]

[0017] [Patent Document 1] U.S. Patent No. 6025520 [Patent Document 2] International Publication No. 2015 / 063388 [Patent Document 3] U.S. Patent Application Publication No. 2001 / 0047106 [Patent Document 4] French Patent No. 3083233 Specification [Overview of the project] [Problems that the invention aims to solve]

[0018] Therefore, one of the objects of the present invention is to provide a method for the recovery / purification of methyl acrylate, more generally methyl or ethyl acrylate, which enables the efficient removal of methyl methoxypropionate by carrying out a series of acid decomposition reactions in the presence of acrylic acid to form 3-methoxypropionic acid and methyl acrylate. [Means for solving the problem]

[0019] The subject of the present invention is a method for the recovery / purification of C1-C2 alkyl acrylates from a reaction mixture resulting from the esterification of acrylic acid with an alcohol selected from methanol and ethanol, characterized in that the method comprises an acidolysis treatment, whereby an alkoxy ester of methyl acrylate or ethyl acrylate can be continuously converted into alkoxypropionic acid.

[0020] According to one embodiment, the acidolysis reaction occurs at a temperature close to the temperature of the esterification reaction.

[0021] According to one embodiment, the alcohol is methanol, the alkyl acrylate is methyl acrylate, the alkyl alkoxypropionate is methyl methoxypropionate (MMP), and the alkoxypropionic acid is methoxypropionic acid (MPA).

[0022] According to one embodiment, the alcohol is ethanol, the alkyl acrylate is ethyl acrylate, the alkyl alkoxypropionate is ethyl ethoxypropionate (EEP), and the alkoxypropionic acid is ethoxypropionic acid (EPA).

[0023] According to one embodiment, the reaction mixture results from the esterification of acrylic acid with a stoichiometric excess of alcohol.

[0024] According to one embodiment, the reaction mixture results from the esterification of acrylic acid with alcohol under conditions where the acid is in stoichiometric excess.

[0025] The acidolysis treatment comprises the following reactions: in the presence of water and acrylic acid (AA), MMP hydrolyzes to form methoxypropionic acid and methanol (MeOH). MMP reacts with acrylic acid to form methyl acrylate and methoxypropionic acid

[0026] MMP hydrolysis reaction: MMP + H2O --> MPA (methoxypropionic acid) + MeOH

[0027] [ka]

[0028] -MMP acid hydrolysis reaction: MMP + AA --> MPA (methoxypropionic acid) + AM

[0029] [ka]

[0030] One or both of these reactions occur depending on the reactants present.

[0031] These reactions occur in a temperature range close to that of esterification reactions (75°C to 85°C), and they are catalyzed by strong acids, such as strong cationic resins.

[0032] These reactions allow for the conversion of methyl methoxypropionate to methoxypropionic acid (boiling point: 206°C at atmospheric pressure). Since the vapor pressure of the latter is significantly different from that of acrylic acid, it can be easily separated from the latter.

[0033] The products from the reactor are sent to an azeotrope column. Azeotropic distillation is understood to mean the separation of the azeotrope (or azeotrope mixture) consisting of a ternary alkyl acrylate / alcohol / water mixture. As described in reference FR3083233, this azeotrope column separating the reaction mixture may be equipped with a side flow extraction to allow for the removal of the MMP / water azeotrope. The bottom flow of the azeotrope column is supplied whole or partially to a heavy processing column. This column separates the flow containing unreacted (meth)acrylic acid as well as trace amounts of alcohol and light products at the top, and separates the flow of heavy by-products at the bottom.

[0034] These heavy by-products, rich in alkoxyester adducts and oligomers, can be subjected to heat treatment in a cracking reactor, releasing an economically upgradeable product stream back into the reaction and generating a residue.

[0035] The top flow from the azeotropic column is fed into a liquid / liquid extraction and purification sequence and one or two distillation columns, enabling the recovery of the purified ester.

[0036] The acid-digesting reactor processes all MMP-rich heavy flows, enabling economically upgradeable raw material recovery and conversion of methyl methoxypropionate to methoxypropionic acid.

[0037] According to one embodiment, the method according to the present invention is carried out in a facility equipped with a purification system optionally comprising an esterification reactor, an azeotropic distillation column, an acid decomposition reactor, a second distillation column and / or a thin-film evaporator, a cracking reactor, a liquid-liquid extraction column, and a partition column.

[0038] According to one embodiment, the acid-decomposing reactor is located in the feed section of the processing tower for heavy materials from the bottom of the azeotrope.

[0039] According to one embodiment, the acid decomposition reaction located in the feed section of the heavy material processing column processes this flow from the bottom of the azeotrope column, optionally a flow from the side outlet, and optionally a purge flow from the bottom of the purification column.

[0040] According to one embodiment, the method according to the present invention involves the following steps: a) A step of azeotropic distillation of a reaction mixture using a first distillation column, wherein at the top, the azeotropic mixture containing alkyl acrylate, unreacted alcohol, and water is separated, and at the bottom, a fraction containing unreacted acrylic acid and heavy by-products is separated, and the fraction rich in alkylalkoxypropionate by-products is removed by side flow extraction, b) An acid digestion step that converts alkylalkoxypropionate to alkoxypropionic acid, thereby enabling the generation of a stream free of alkylalkoxypropionate to be supplied to the heavy separation column, c) A column separation step of separating the bottom flow from the azeotropic column into a flow essentially containing the unreacted acrylic acid and being recycled to the esterification reactor, and a flow essentially containing heavy by-products, being subjected to thermal decomposition, and releasing a recyclable flow of economically upgradeable products, d) A cracking step which allows for the economical upgrade of the raw materials contained in the by-product and the purging of residues, e) A liquid-liquid extraction step of the top flow from a first distillation column using an aqueous flow, which enables the separation of an organic phase essentially containing alkyl acrylate from an aqueous phase, the aqueous phase being distilled to recover, on the one hand, an alcohol-rich fraction that can be recycled to the reactor, and on the other hand, a water-rich fraction that can be used as an aqueous flow in the liquid-liquid extraction step; f) A purification step of the organic phase that enables the recovery of the purified alkyl acrylate; g) An optional recirculation step of purging from the purification sequence, which is rich in alkoxy esters, after the acid hydrolysis step. Includes.

[0041] The present invention makes it possible to overcome the shortcomings of the prior art concerning the formation of alkylalkoxypropionate byproducts in methods for the synthesis of methyl acrylate or ethyl acrylate by direct esterification of acrylic acid with a corresponding alcohol.

[0042] The method according to the present invention enables the efficient removal of alkylalkoxypropionates and reduces the loss of economically upgradeable products caused by purging imposed by the accumulation of alkylalkoxypropionates during the purification sequence.

[0043] Therefore, the present invention provides a simplified method for producing high-purity methyl or ethyl acrylate and optimizes the mass balance of the method. [Brief explanation of the drawing]

[0044] [Figure 1] A diagrammatic representation of a plant for producing methyl acrylate, including the acid decomposition step according to the present invention. [Modes for carrying out the invention]

[0045] Next, the present invention will be described in more detail and indefinitely in the following description by comparing it with methods of the prior art.

[0046] For simplicity, the explanation will be based on the example of methyl acrylate obtained by esterification of acrylic acid with methanol. The solution proposed by the present invention is applied in the same manner to the use of ethanol in esterification reactions and also to other components of the purification sequence (azeotropic distillation without side flow extraction, methods using topping columns and rectification columns or partitioned columns for final purification).

[0047] Figure 1 shows a prior art plant for producing methyl acrylate.

[0048] The reaction section includes an esterification reactor R1. Reactor R1 is supplied by an acrylic acid supply line 1 and a methanol supply line 2. The reactor preferably contains a heterogeneous catalyst of the acidic cation exchange resin type. In the case of homogeneous catalysis, the reactor is further supplied by a catalyst supply line (not shown). The esterification reaction can be carried out in excess methanol or excess acrylic acid.

[0049] Esterification reactions can be carried out with excess alcohol (in which case the acid / alcohol molar ratio is 0.6–1) or excess acrylic acid (in which case the acid / alcohol molar ratio is 1.05–3), and it is understood that the acid / alcohol molar ratio refers to the acid and alcohol content of all flows supplied to the esterification reactor (the pure product flow and the recirculated flow).

[0050] Esterification reactions can be carried out under pressures ranging from atmospheric pressure (100,000 Pa) to three times that value (300,000 Pa), or under reduced pressure.

[0051] In the case of heterogeneous catalysis, the esterification reaction is carried out in the presence of an acid catalyst, such as an acidic cation exchange resin, or in the case of homogeneous catalysis, sulfuric acid or organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, or dodecylsulfonic acid, or mixtures thereof, may be used as catalysts. The esterification reaction is preferably carried out under atmospheric pressure by heterogeneous catalysis.

[0052] The reaction is generally carried out in the presence of one or more polymerization inhibitors introduced into the reactor at a concentration of 500 to 5000 ppm relative to the crude reaction mixture.

[0053] At the outlet of reactor R1, the reaction mixture 3 is sent to the azeotropic distillation unit C8. The configuration of the distillation column C8 allows for the separation of a stream 11 at the top, consisting of the formed methyl acrylate, unreacted methanol, and water produced by the reaction, as well as an azeotropic mixture containing further light and heavy impurities; a stream 6 at the bottom, essentially containing unreacted acrylic acid, trace amounts of light and heavy products; and a stream 19 that is withdrawn as a side stream.

[0054] Stream 19 contains most of the MMP formed as a byproduct during esterification. Stream 19 is an MMP-rich stream, but may also contain methyl acrylate, methanol, acrylic acid, and water.

[0055] Flow 19 can be advantageously sent to the acid-decomposing reactor R2, where it can convert MMP to MPA and then feed to column C2 for processing the heavy by-products.

[0056] Alternatively, the flow 19 can be subjected to purification (not shown) to recover purified methyl methoxypropionate on one end and economically upgradeable compounds such as methyl acrylate, methanol, and acrylic acid on the other.

[0057] At the bottom of the distillation column C8, stream 6 is separated, which essentially contains unreacted acrylic acid, trace amounts of light products (with boiling points lower than that of acrylic acid), and heavy products (oligomers and Michael adducts of acrylic acid) with boiling points higher than that of acrylic acid.

[0058] Stream 6 is sent entirely or partially to the acid digestion reactor R2, and then to the distillation column and / or thin film evaporator C2, which separates stream 7, containing residual acrylic acid and lighter products, from stream 8, which essentially consists of heavier products. Stream 7 is advantageously recycled to reactor R1.

[0059] Flow 8 can be subjected to thermal decomposition, which allows for the recycling of potentially recoverable noble products (starting compounds or final products) from the heavy product fraction. Thermal decomposition is generally carried out at temperatures that may range, for example, from 120°C to 220°C, in the presence of an acid catalyst such as sulfuric acid or sulfonic acid, which can be optional. The final residue from this cracker is sent to incineration, while the economically upgraded products are recycled back into the reaction via flow 23.

[0060] The azeotropic distillation unit separates the stream 11 at the top, which consists of an azeotropic mixture containing the formed methyl acrylate, unreacted methanol, water produced by the reaction, and light and heavy impurities.

[0061] The top flow 11 from the azeotropic distillation unit is sent to a precipitation section (settling tank or contactor), which generates an aqueous phase 17A essentially containing methanol on the one hand and an organic phase 12 on the other.

[0062] The liquid-liquid extraction section generally consists of a packed or agitated liquid-liquid extraction column, a mixer-sedimentation tank battery, and one or more sedimentation tanks in series. The liquid-liquid extraction section produces an alcohol-depleted organic phase 14 and an aqueous phase 17B.

[0063] In the plant shown in Figure 1, the aqueous phase 17 is subjected to distillation in distillation column C5 to separate methanol, which is then recycled back to the reactor after an optional dehydration step (flow 5). The methanol-depleted aqueous flow 18 can then be recycled back to the liquid-liquid extraction phase.

[0064] The organic phase 14 is subjected to a purification sequence to recover methyl acrylate with the purity required for subsequent use. Generally, a purity of over 99.5%, and even over 99.8%, is desirable.

[0065] To do this, the organic phase 14 can be subjected to one or more sequential complementary distillation steps.

[0066] According to one embodiment of the present invention, the organic phase 14 is purified using a purification system comprising at least one partitioned column having internal partial partitions and a sedimentation tank that create separation zones within the column. This purification system is represented as C9 in Figure 1 and separates a stream 13 containing most of the light compounds at the top, a stream 16 containing most of the heavy compounds at the bottom, and a stream 15 of purified methyl acrylate that is withdrawn as a side stream.

[0067] Flow 13 consists of a condensed light flow in the form of an aqueous phase and an organic phase. The organic phase is partially used as reflux for the bulkhead and then purged, while the aqueous phase is treated toward the biological station.

[0068] Flow 16 is purged, but can also be recycled to the acid decomposition reactor R2.

[0069] Therefore, the acid digestion reactor R2 receives a combination of flows 19, 16, and 6, which are rich in MMP, and the feed contains at least 50% acrylic acid. To accelerate the reaction, an aqueous flow (flow 18), not shown, may also be added.

[0070] The effectiveness of the inhibitor is also related to the injection of air or depleted air into the various towers in which it is used.

[0071] Examples of possible polymerization inhibitors include phenothiazine (PTZ), hydroquinone (HQ), hydroquinone monomethyl ether (HQME), di-tert-butyl-para-cresol (BHT), para-phenylenediamine, TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy), di-tert-butylcatechol, or TEMPO derivatives such as OH-TEMPO, which can be used individually or in any proportion as mixtures thereof, in the presence of depleted air, at concentrations of 50 ppm to 5000 ppm in the reaction medium, but generally at concentrations of 150 ppm to 1000 ppm.

[0072] The addition of polymerization inhibitors can be carried out at various locations, including at the introduction of the reactants or at the top of the distillation column.

[0073] The present invention makes it possible to limit the loss of economically upgradeable materials such as acrylic acid, alcohol, or alkyl acrylate in a method for producing light alkyl acrylates by direct esterification.

[0074] The acid-decomposing reactor, supplied by multiple flows, contains a large amount of MMP and acrylic acid, and depending on the added flow, it contains varying amounts of light esters, water, and oligomers.

[0075] The acid decomposition catalyst is an acid catalyst selected from the following list: sulfuric acid, methylsulfonic acid, p-toluenesulfonic acid, and strongly acidic cationic resins.

[0076] According to one embodiment, the catalyst is a homogeneous catalyst. The homogeneous catalyst used may be an acid such as sulfuric acid, methylsulfonic acid, or p-toluenesulfonic acid.

[0077] According to one embodiment, the catalyst is a heterogeneous catalyst. In heterogeneous catalytic action, the catalyst is a gel or macroporous strongly acidic cationic resin such as Amberlist 131 or Amberlist 15, and is used in the form of a fixed-bed reactor or a stirred reactor (suspension).

[0078] The residence time in the acid decomposition reactor can vary from 0.2 to 6 hours, preferably 0.5 to 5 hours. The temperature in the acid decomposition reactor is 50 to 100°C, preferably 70 to 90°C, close to the temperature of the esterification reaction, during which time the reactants are maintained in their liquid form.

[0079] According to one embodiment, the molar ratio of AA to MMP is 1 to 11, preferably 4 to 9. An aqueous stream can be added to the mixture to accelerate the hydrolysis reaction.

[0080] The following examples illustrate the present invention and are not intended to limit the scope of the invention as defined by the appended claims. [Examples]

[0081] In the embodiments, unless otherwise indicated, percentages are expressed in weight, and the following abbreviations are used.

[0082] AA: Acrylic acid MA: Methyl acrylate MMP: Methylmethoxypropionate MeOH: methanol

[0083] [Example 1] Acid decomposition reaction of MMP with or without water: Case with excess AA: AA + MMP (with or without water) The MMP acid decomposition reaction is carried out in batch mode, either without water or in the presence of water. In a round-bottom flask, tAA (industrial-grade acrylic acid with purity >99%) and MMP are introduced into an excess of AA (tAA / MMP molar ratio = 5), and 20% by mass of dry resin is added. The mixture is held at 80°C for 5 hours and then completely refluxed. Table 1 summarizes the reaction conditions.

[0084] Conversion rate = (Final number of moles - Initial number of moles) / Initial number of MeOH moles.

[0085] [Table 1]

[0086] Under these conditions, MMPs are readily converted to methoxypropionic acid by acid hydrolysis in the absence of water, and a considerable amount of MA is also formed (69%–85% conversion). The presence of water undoubtedly accelerates the disappearance of MMPs through hydrolysis.

Claims

1. C from the reaction mixture obtained from the esterification of acrylic acid with an alcohol selected from methanol and ethanol. １ -C ２ A method for purifying alkyl acrylates, wherein the reaction mixture is rich in acrylic acid produced from esterification, and the method includes an acid decomposition treatment, thereby enabling the continuous conversion of alkoxy esters of methyl acrylate or ethyl acrylate to alkoxypropionic acid at a temperature of 50 to 100°C, preferably 70 to 90°C, in the presence of a homogeneous or heterogeneous catalyst.

2. The method according to claim 1, carried out in a facility comprising a purification system optionally including an esterification reactor, an azeotropic distillation column, an acid decomposition reactor, a second distillation column and / or a thin-film evaporator, a cracking reactor, a liquid-liquid extraction column, and a partitioned column.

3. The method according to claim 1 or 2, wherein the alcohol is methanol, the alkyl acrylate is methyl acrylate, the alkyl alkoxypropionate is methyl methoxypropionate, and the alkoxypropionic acid is methoxypropionic acid.

4. The method according to claim 1 or 2, wherein the alcohol is ethanol, the alkyl acrylate is ethyl acrylate, the alkyl alkoxypropionate is ethyl ethoxypropionate, and the alkoxypropionic acid is ethoxypropionic acid.

5. The method according to any one of claims 1 to 4, wherein the acid decomposition catalyst is an acid catalyst selected from the following list: sulfuric acid, methylsulfonic acid, p-toluenesulfonic acid, and a strongly acidic cationic resin.

6. The method according to any one of claims 1 to 5, wherein the temperature inside the acid decomposition reactor is 50 to 100°C, preferably 70 to 90°C.

7. The method according to any one of claims 1 to 6, wherein the pressure inside the acid decomposition reactor is 100,000 Pa to 300,000 Pa.

8. The method according to any one of claims 1 to 7, wherein the residence time in the acid decomposition reactor is 0.2 to 6 hours.

9. The method according to any one of claims 1 to 8, wherein the molar ratio of acrylic acid (AA) to methyl methoxypropionate (MMP) at the inlet of the acid decomposition reactor is 1 to 11, preferably 4 to 9.

10. The method according to any one of claims 1 to 9, wherein the reaction mixture is obtained by esterification of acrylic acid with a stoichiometrically excess alcohol, and the molar ratio of acid to alcohol is 0.6 to 1.

11. The method according to any one of claims 1 to 4, wherein the reaction mixture is obtained from the esterification of acrylic acid with an alcohol under conditions in which the acid is stoichiometrically in excess, and the molar ratio of acid to alcohol is 1.05 to 3.

12. The method according to claim 5, wherein the catalyst is a strongly acidic cationic resin, and the catalyst esterification reactor is a fixed-bed reactor or a stirred reactor.

13. The method according to any one of claims 1 to 12, wherein a polymerization inhibitor is introduced into the esterification reactor at a concentration of 500 to 5000 ppm relative to the crude reaction mixture.

14. The method according to any one of claims 1 to 13, wherein the azeotrope column can be equipped with a side flow extraction.

15. The method according to any one of claims 1 to 14, wherein the cracking is a catalyst-free thermal decomposition.

16. The aforementioned method involves the following steps: a) A step of azeotropic distillation of a reaction mixture using a first distillation column, wherein at the top, the azeotropic mixture containing alkyl acrylate, unreacted alcohol, and water is separated, and at the bottom, a fraction containing unreacted acrylic acid and heavy by-products is separated, and the fraction rich in alkylalkoxypropionate by-products is removed by side flow extraction, b) An acid digestion step that converts alkylalkoxypropionate to alkoxypropionic acid, thereby enabling the generation of an alkylalkoxypropionate-free stream to be fed to the heavy separation column, c) A column separation step of separating the bottom flow from the azeotropic column into a flow essentially containing the unreacted acrylic acid and being recycled to the esterification reactor, and a flow essentially containing heavy by-products, being subjected to thermal decomposition, and releasing a recyclable flow of economically upgradeable products, d) A cracking step that allows for the economical upgrade of the raw materials contained in the by-product and the purging of residues, e) A liquid-liquid extraction step of the top flow from a first distillation column using an aqueous flow, which enables the separation of an organic phase essentially containing alkyl acrylate from an aqueous phase, the aqueous phase being distilled to recover, on the one hand, an alcohol-rich fraction that can be recycled to the reactor, and on the other hand, a water-rich fraction that can be used as an aqueous flow in the liquid-liquid extraction step, f) A purification step of the organic phase that enables the recovery of the purified alkyl acrylate, g) An optional recirculation step of purging from the purification sequence, which is rich in alkoxy esters, after the acid hydrolysis step, The method according to claim 2, including the method described in claim 2.

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