A process for the preparation of butyl acrylate

Abstract

The application discloses a preparation method of butyl acrylate. The butyl acrylate is prepared through esterification reaction of raw materials of acrylic acid and n-butanol. The acrylic acid includes acryloyloxypropionic acid, maleic acid and crotonic acid. The mass ratio of the acryloyloxypropionic acid to the maleic acid is 1:0.01-1, and the mass ratio of the crotonic acid to the acryloyloxypropionic acid is 1:5-500. The content of key impurities in the acrylic acid is ensured to be in a specific ratio, and the crude acrylic acid is directly used as a raw material for butyl acrylate production after removal of light components, so that the production cost of the butyl acrylate is greatly reduced, and raw material consumption and energy consumption are reduced. The application is a green and efficient production process.

Description

Technical Field

[0001] This invention belongs to the field of butyl acrylate production, and specifically relates to a method for preparing butyl acrylate. Background Technology

[0002] Butyl acrylate is a colorless and transparent liquid that is insoluble in water but miscible with ethanol and ether. It has a wide range of applications in coatings, adhesives, acrylic fiber modification, plastic modification and many other fields.

[0003] The direct esterification reaction of acrylic acid and n-butanol to prepare butyl acrylate is currently the main industrial production process. Patent CN 118615975 A describes a production system and process for butyl acrylate. This system includes a butyl acrylate reactor, a butyl acetate separation unit, and a butyl acrylate output unit. The process uses n-butanol and acrylic acid as raw materials to produce crude butyl acrylate via the reactor. The butyl acetate separation unit separates butyl acetate from the crude butyl acrylate and recovers it through alkaline hydrolysis. The butyl acrylate output unit then purifies the butyl acrylate. The final butyl acrylate produced has a purity greater than 99.7%. This patent adds a butyl acetate separation system to the existing process technology, relaxing the requirements for the acetic acid impurity content in the acid feedstock. It can produce high-quality butyl acrylate, but the cost of the raw material acrylic acid remains relatively high, mainly because a large amount of tar needs to be removed during the removal of heavy components from the acrylic acid, resulting in significant material consumption.

[0004] The raw material acrylic acid may contain impurities such as esters and acids during the preparation process. Usually, acrylic acid needs to be distilled to control the content of these impurities to a low level. Otherwise, these impurities are easily introduced into the preparation process of butyl acrylate, and will react with butanol to generate more ester impurities that are difficult to separate from butyl acrylate, increasing the difficulty of subsequent separation processes of butyl acrylate and significantly increasing costs.

[0005] Therefore, the preparation process of butyl acrylate requires high purity of the raw material acrylic acid, which increases production costs. Summary of the Invention

[0006] To address the aforementioned shortcomings of the prior art, this invention provides a method for preparing butyl acrylate. By controlling the content of key additives and impurities in the raw material acrylic acid, the purity requirements for acrylic acid in butyl acrylate production are reduced, thereby lowering production costs.

[0007] The method of this invention can reduce the risk of acrylic acid polymerization and control the formation of polymers in acrylic acid. On the other hand, various impurities in acrylic acid will participate in the reaction to generate corresponding ester impurities when they enter the butyl acrylate process, which will consume butanol. However, in the subsequent separation process, the ester impurities generated by the heavy components can be decomposed and removed by optimizing the process. However, the decomposition ability of the ester impurities of the heavy components in the esterification process varies. Therefore, the ratio of various impurities in the crude acid needs to be specified to ensure that each impurity is fully decomposed and recovered. The removal of impurities ensures the quality of butyl acrylate products while reducing the consumption of butanol and reducing the production cost of butyl acrylate.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A method for preparing butyl acrylate involves esterifying acrylic acid and n-butanol to obtain butyl acrylate. The acrylic acid comprises acryloyloxypropionic acid, maleic acid, and crotonic acid. The mass ratio of acryloyloxypropionic acid to maleic acid is 1:0.01-1, more preferably 1:0.1-0.8; the mass ratio of crotonic acid to acryloyloxypropionic acid is 1:5-500, more preferably 1:20-100.

[0010] This study found that acryloyloxypropionic acid, maleic acid, and crotonic acid in crude acrylic acid all undergo esterification reactions with butanol to produce butyl maleate, dibutyl maleate, butyl acryloyloxypropionic acid, and butyl crotonic acid, respectively. The conversion rate of impurities to butanol varies under different raw material ratios. By controlling the impurity ratio, incomplete reactions of maleic acid and crotonic acid can be avoided. Unreacted maleic acid forms maleic anhydride and fumaric acid at high temperatures, whose boiling points are close to those of butyl acrylate, making them difficult to separate and affecting the purity of butyl acrylate.

[0011] Preferably, the acrylic acid has a purity of 90.0% or higher, more preferably less than or equal to 99.8%, further preferably 94%-99.8%, and even more preferably 94%-99.5%.

[0012] Preferably, the acrylic acid contains 0.2%-8% by mass, more preferably 0.6%-5%.

[0013] Preferably, the acrylic acid is prepared by two-step oxidation of propylene and air or oxygen as raw materials.

[0014] Preferably, water is used as an absorbent during the preparation of the acrylic acid.

[0015] Preferably, the crude acrylic acid reaction solution is prepared by two-step oxidation using propylene and air or oxygen as raw materials.

[0016] The crude acrylic acid reaction solution enters a light component fractionation tower and an acetic acid removal tower to remove light component impurities such as water, acetic acid, and formaldehyde. Then, it enters an acid purification tower for distillation to remove heavy component impurities such as dimers, maleic acid, and benzaldehyde, to obtain acrylic acid.

[0017] Preferably, the crude acrylic acid reaction solution enters a light component distillation column, where the top temperature of the distillation column is controlled at 13-16 kPa, the bottom temperature is controlled at 40-45°C, the bottom pressure is controlled at 18-22 kPa, and the bottom temperature is controlled at 77-82°C.

[0018] Preferably, the light component distillation column adopts azeotropic distillation, and the mass ratio of azeotropic agent to crude acrylic acid reaction liquid feed is 2:1-4:1; preferably, the azeotropic agent is toluene.

[0019] Preferably, the crude acrylic acid stream after distillation in the light component distillation column enters the acetic acid removal column to remove impurities such as acetic acid. The pressure at the top of the column is controlled at 4-6 kPaa and the temperature is controlled at 50-60°C; the pressure at the bottom of the column is controlled at 9-12 kPaa and the temperature is controlled at 77-85°C.

[0020] Preferably, the acrylic acid, after being deaceticated in the deacetic acid tower to remove light components such as acetic acid, may be further purified in an acid purification tower. The pressure at the top of the acid purification tower is controlled at 2-4 kPa, and the temperature is controlled at 48-55°C. The pressure at the bottom of the tower is controlled at 6-8 kPa, and the temperature is controlled at 75-80°C.

[0021] Preferably, the crude acrylic acid reaction solution further includes the auxiliary agents 2,4-dimethyldithiocarbamate (referred to as organic copper salt) and phenothiazine, with the mass ratio of 2,4-dimethyldithiocarbamate (referred to as organic copper salt) to phenothiazine being 1:(5-100), more preferably 1:(5-20).

[0022] Preferably, the amount of phenothiazine added to the crude acrylic acid reaction solution is 0.05-0.12 wt% of the mass of the crude acrylic acid reaction solution.

[0023] In this application, by adding additives and controlling parameters such as process parameters and additive addition amount in the distillation process, the polymerization of acrylic acid can be effectively controlled, and the polymer content in the crude acrylic acid before entering the acid purification tower for deweighting can be controlled at a low level, so as to avoid polymerization problems caused when entering the butyl ester process; at the same time, the additive can continue to play an inhibitory role in polymerization when it enters the butyl ester process with the crude acrylic acid, and play an inhibitory role in controlling the polymerization in the butyl ester reactor.

[0024] The method for preparing butyl acrylate involves esterification of acrylic acid with n-butanol, followed by removal of impurities through a separation process to obtain the butyl acrylate product.

[0025] Preferably, the esterification reaction temperature of butyl acrylate is 35-53 kPa, and the temperature is 92-98°C; the conversion of acrylic acid is promoted by excess butanol, and the molar ratio of butanol to acrylic acid is 1.1-1.3:1;

[0026] Preferably, the esterification reaction uses an acid as a catalyst, and the acid catalyst is one or more of p-toluenesulfonic acid or methanesulfonic acid; the amount of the acid catalyst is 0.5%-2wt% of the total mass of the esterification reaction raw materials acrylic acid and n-butanol;

[0027] Preferably, the butyl acrylate separation process includes catalyst extraction and recovery, neutralization and washing, alcohol decanting tower, ester purification tower, and heavy component recovery system;

[0028] Preferably, the extraction and recovery step uses water as the extractant to extract the catalyst from the crude ester after esterification into the aqueous phase, which is then sent to the esterification reactor for recycling. The ratio of extractant to crude ester is 0.5-2:15.

[0029] Preferably, the neutralization and washing step involves neutralizing and washing the crude ester with NaOH solution, neutralizing the incompletely reacted acrylic acid to generate sodium acrylate, which is then removed into the wastewater.

[0030] Preferably, the alcohol top column is a light component separation column. After extraction, neutralization and washing, the crude ester enters the alcohol top column, and light component impurities such as butanol and butyl acetate are removed to the top of the column and recycled back to the reaction system.

[0031] Preferably, the ester purification tower is a heavy component removal tower. After removing light components, the crude ester enters the ester purification tower to remove heavy component impurities, thereby obtaining butyl ester product. The removed heavy component impurities enter the heavy component recovery system for decomposition and recovery.

[0032] The butyl ester heavy component recovery system incorporates an acid catalyst, including one or more of methanesulfonic acid and p-toluenesulfonic acid, wherein the amount of acid catalyst added is 0.5%-5% of the total mass of the system, more preferably 0.6%-2%.

[0033] The temperature of the butyl ester recombination and decomposition system is controlled at 170℃-220℃, more preferably 175℃-200℃; the pressure is 80Kpaa-101.3Kpaa, more preferably 90Kpaa-101.3Kpaa; and the residence time is 2-10h, more preferably 4-8h.

[0034] Under the above-mentioned pyrolysis conditions, the key impurities undergo a pyrolysis reaction in the butyl ester recombinant pyrolysis unit, whereby butyl acryloyloxypropionate is pyrolyzed to produce acrylic acid and butyl acrylate, and butyl maleate is pyrolyzed to produce maleic acid and butanol.

[0035] After the impurities are cracked in the butyl ester recombination and decomposition system, they are sent from the top gas phase to the butyl ester esterification reactor for recovery, realizing the conversion and recycling of impurities and significantly reducing production and operating costs; at the same time, the residual materials after recombination and decomposition are either discharged as tar and incinerated or sold as hazardous waste.

[0036] The amount of tar discharged directly affects the amount of butyl acrylate product and the impact on raw material consumption. After using crude acid as esterification raw material, the amount of tar discharged after recombination and decomposition can be maintained at 10-40 kg / t butyl acrylate product, and even more preferably at 15-25 kg / t butyl acrylate product, which can reduce the production cost of butyl acrylate.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] Existing technologies for butyl acrylate use polymer-grade acrylic acid as the raw material, requiring a purity of over 99.5%. This places high demands on the purification and refining of acrylic acid, increasing operating costs and indirectly raising the production cost of butyl acrylate. This invention controls the content of various impurities in the acrylic acid product to meet specific relationships, allowing the acrylic acid, after being purified by distillation to remove light impurities such as acetic acid, formaldehyde, and acrolein, to be directly fed to butyl acrylate as a raw material for the esterification reaction. By adjusting the process parameters of the butyl acrylate recombination decomposer, the production cost of butyl acrylate is reduced without affecting the quality of the butyl acrylate product, while using acrylic acid as a raw material. Detailed Implementation

[0039] The invention will be further described below with reference to the embodiments. The scope of protection of the present invention includes, but is not limited to, the embodiments.

[0040] Raw material source:

[0041] Copper 2,4-dimethyldithiocarbamate, Taian Crystal Ring;

[0042] Phenothiazine, Shandong Daguan.

[0043] Example 1:

[0044] A crude acrylic acid reaction solution was prepared by a two-step oxidation process using propylene and oxygen as raw materials, with water used as the absorbent during the acrylic acid preparation. The crude acrylic acid reaction solution was supplemented with auxiliaries 2,4-dimethyldithiocarbamate (referred to as organic copper salt) and phenothiazine, with a mass ratio of 2,4-dimethyldithiocarbamate to phenothiazine of 1:20, wherein the amount of phenothiazine added was 0.12 wt% of the crude acrylic acid reaction solution.

[0045] The crude acrylic acid reaction solution was purified and separated by a light component fractionation column (toluene azeotropic distillation) and an acetic acid removal column to obtain acrylic acid. The process parameters for the purification process were controlled as follows: Light component fractionation column top pressure 13 kPa, temperature 40℃, bottom pressure 18 kPa, toluene to crude acrylic acid mass ratio 2:1; temperature 77℃. Acetic acid removal column top pressure controlled at 4 kPa, temperature controlled at 50℃; bottom pressure controlled at 9 kPa, temperature controlled at 77℃.

[0046] The mass ratio of acryloyloxypropionic acid to maleic acid in the obtained acrylic acid is 1:0.8, the mass ratio of crotonic acid to acryloyloxypropionic acid is 1:20, and the content ratio of organic copper salt to phenothiazine in the auxiliary agent is 1:20. (The main components of acrylic acid are shown in Table 1, and the rest are other impurities that are not listed for the time being.)

[0047] Table 1. Main components of the purified acrylic acid

[0048]

[0049] Butyl acrylate was produced using acrylic acid and n-butanol prepared in this embodiment as raw materials. The esterification reaction temperature was 92°C, the pressure was 35 kPa, and the molar ratio of butanol to acrylic acid was 1.1:1. Methanesulfonic acid was used as the catalyst, at a dosage of 0.5 wt% of the reactants.

[0050] The butyl acrylate reaction solution obtained by esterification reaction was extracted and recovered using water as the catalyst. Then, the crude ester was neutralized and washed with NaOH solution. After passing through the light component separation tower to remove light components and the ester purification tower to remove heavy components, butyl acrylate was obtained.

[0051] The butyl ester recombinant fraction obtained from the ester purification tower was recovered via butyl ester recombinant decomposition. The reaction used methanesulfonic acid as a catalyst (3 wt%), the butyl ester recombinant decomposition reactor temperature was 175℃, the pressure was 90 kPaa, the reaction time was 4 h, and the tar discharge after decomposition was 25 kg / t of butyl ester product. The butyl ester product specifications are shown in Table 2.

[0052] Table 2 Butyl ester product indicators

[0053]

[0054] Example 2:

[0055] The crude acrylic acid refining and esterification process follows the same flow as in Example 1, except that the ratio of the auxiliary agent organic copper salt to phenothiazine is 1:5, and the amount of phenothiazine added is 0.05% of the crude acrylic acid mass. The process parameters for refining and purifying the crude acrylic acid reaction solution and the esterification process parameters are adjusted to regulate the proportions of various impurities in the crude acrylic acid, specifically as follows: Light component fractionation column top pressure 16 kPa, temperature 45°C, bottom pressure 22 kPa, toluene to crude acrylic acid mass ratio 4:1; temperature 82°C. Acetic acid removal column top pressure controlled at 6 kPa, temperature controlled at 60°C; bottom pressure controlled at 12 kPa, temperature controlled at 85°C.

[0056] The mass ratio of acryloyloxypropionic acid to maleic acid in the obtained acrylic acid was 1:0.1, and the mass ratio of crotonic acid to acryloyloxypropionic acid was 1:105. (The main components of the crude acrylic acid raw material are shown in Table 3. Other impurities are not listed.)

[0057] Butyl acrylate was produced using crude acrylic acid and n-butanol prepared in this embodiment as raw materials. The esterification reaction temperature was 98°C, the pressure was 53 kPa, and the molar ratio of butanol to acrylic acid was 1.3:1. Methanesulfonic acid was used as the catalyst, and its dosage was 2 wt% of the reactants.

[0058] Butyl acrylate was separated and its recombinant components were recovered using the same method as in Example 1. The recombinant decomposition of butyl acrylate used methanesulfonic acid as a catalyst (1% concentration), the temperature of the butyl acrylate decomposition reactor was 200℃, the pressure was 101.3 kPaa, the reaction time was 8 hours, and the tar discharge after decomposition was 18 kg / t of butyl acrylate product. The butyl acrylate product specifications are shown in Table 4.

[0059] Table 3 Main components of acrylic acid

[0060]

[0061] Table 4 Butyl Acetate Product Indicators

[0062]

[0063] Example 3

[0064] The crude acrylic acid refining and esterification process follows the same procedure as in Example 1, except that the ratio of the auxiliary agent organic copper salt to phenothiazine is 1:55, and the amount of phenothiazine added is 0.08% of the crude acrylic acid mass. The pressure at the top of the deacetic acid tower is controlled at 5 kPa and the temperature at 60°C; the pressure at the bottom of the tower is controlled at 12 kPa and the temperature at 79°C.

[0065] The mass ratio of acryloyloxypropionic acid to maleic acid in the obtained acrylic acid was 1:0.05, and the mass ratio of crotonic acid to acryloyloxypropionic acid was 1:95. (The main components of the acrylic acid raw material are shown in Table 5. Other impurities are not listed here.)

[0066] The composition of the obtained acrylic acid is shown in Table 5. Butyl acrylate was prepared using the same method as in Example 1, and the composition of the butyl acrylate product is shown in Table 6. The butyl acrylate was separated and the recombinant components were recovered using the same method as in Example 1. The tar discharge after recombinant decomposition was 14 kg / t of butyl acrylate product.

[0067] Table 5 Main components of acrylic acid

[0068]

[0069] Table 6 Butyl Acetate Product Indicators

[0070]

[0071] Example 4

[0072] The crude acrylic acid refining and esterification process follows the same flow as in Example 1, except that the ratio of the auxiliary agent organic copper salt to phenothiazine is 1:80, and the amount of phenothiazine added is 0.1% of the mass of crude acrylic acid. The pressure at the top of the light component fractionation column is 15 kPa, the temperature is 45°C, the pressure at the bottom of the column is 18 kPa, the mass ratio of toluene to crude acrylic acid is 3:1, and the temperature is 80°C.

[0073] The mass ratio of acryloyloxypropionic acid to maleic acid in the obtained acrylic acid is 1:0.5, and the mass ratio of crotonic acid to acryloyloxypropionic acid is 1:56. (The main components of the crude acrylic acid raw material are shown in Table 7. The rest are other impurities and are not listed for the time being.)

[0074] The composition of the obtained acrylic acid is shown in Table 7. Butyl acrylate was prepared using the same method as in Example 1, and the composition of the butyl acrylate product is shown in Table 8. The butyl acrylate was separated and the recombinant components were recovered using the same method as in Example 1. The tar discharge after recombinant decomposition was 17 kg / t of butyl acrylate product.

[0075] Table 7 Main Components of Acrylic Acid

[0076]

[0077] Table 8. Product Indicators of Butyl Acetate

[0078]

[0079] Comparative Example 1:

[0080] Acrylic acid and butyl acrylate were prepared using the same method as in Example 1, except that maleic acid and crotonic acid were added to the obtained acrylic acid to make the mass ratio of acryloyloxypropionic acid to maleic acid 1:

[0081] 1.5, the mass ratio of crotonic acid to acryloyloxypropionic acid is 1:4. The composition of the crude acrylic acid obtained is shown in Table 9, and the composition of the butyl ester product obtained is also shown in Table 9. After the content of maleic acid and crotonic acid impurities in acrylic acid increased, the content of butyl crotonic acid and maleic anhydride impurities in the butyl ester product exceeded the standard, which also led to excessive color.

[0082] After the production of butyl acetate, the heavy components of butyl acetate undergo cracking, resulting in a tar discharge of 46 kg / h, which has a significant impact on the consumption of raw materials for butanol and acrylic acid.

[0083] Table 9 Butyl Acetate Product Indicators

[0084]

[0085] Comparative Example 2:

[0086] Acrylic acid and butyl acrylate were prepared using the same method as in Example 1, except that the amount and ratio of additives in the acrylic acid were adjusted, the amount of phenothiazine added was 0.03%, and the mass ratio of organic copper salt to phenothiazine was 1:3.

[0087] The composition of the obtained acrylic acid is shown in Table 10, and the composition of the butyl ester product is shown in Table 11. After reducing the amount of the polymerization inhibitor phenothiazine and adjusting the polymerization inhibitor ratio, the polymer content in the crude acrylic acid increased, and the content of acryloyloxypropionic acid increased significantly, resulting in the butyl ester product exceeding the standard. In addition, after the production of butyl ester, the heavy components of butyl ester undergo cracking, and the amount of tar discharged is 62 kg / h, which has a significant impact on the raw material consumption of butanol and acrylic acid.

[0088] Table 10 Main Components of Crude Acrylic Acid

[0089]

[0090] Table 11 Butyl Acetate Product Specifications

[0091]

[0092] Comparative Example 3:

[0093] Acrylic acid and butyl acrylate were prepared using the same method as in Example 1. The difference was that no additives were added to the crude acrylic acid reaction solution. The composition of the crude acrylic acid and the composition of the butyl acrylate product obtained were shown in Tables 12 and 13. The polymer content and acryloyloxypropionic acid content in the crude acrylic acid were very high, which did not meet the conditions for producing butyl acrylate. The purity and various indicators of the produced butyl acrylate did not meet the standards. Moreover, the discharge of the recombinant fraction after the production of butyl acrylate reached 126 kg / t, which seriously affected the production cost of butyl acrylate and was not feasible.

[0094] Table 12 Main Components of Crude Acrylic Acid

[0095]

[0096] Table 13 Main components of butyl acrylate

[0097]

Claims

1. A method for preparing butyl acrylate, characterized in that, Butyl acrylate is prepared by esterification reaction of acrylic acid and n-butanol. The acrylic acid includes acryloyloxypropionic acid, maleic acid, and crotonic acid. The mass ratio of acryloyloxypropionic acid to maleic acid is 1:0.01-1, more preferably 1:0.1-0.8; the mass ratio of crotonic acid to acryloyloxypropionic acid is 1:5-500, more preferably 1:20-100.

2. The preparation method according to claim 1, characterized in that, The acrylic acid has a purity of 90.0% or more, preferably less than or equal to 99.8%, more preferably 94%-99.8%, and even more preferably 94%-99.5%. Preferably, the acrylic acid contains 0.2%-8% by mass, more preferably 0.6%-5%; Preferably, the acrylic acid is acrylic acid prepared by two-step oxidation using propylene and air or oxygen as raw materials; Preferably, water is used as an absorbent during the preparation of the acrylic acid.

3. The preparation method according to claim 1 or 2, characterized in that, Crude acrylic acid reaction solution is prepared by two-step oxidation of propylene and air or oxygen as raw materials. The crude acrylic acid reaction solution enters a light component fractionation tower and an acetic acid removal tower to remove light component impurities. Preferably, the crude acrylic acid reaction solution enters a light component distillation column, where the top temperature of the distillation column is controlled at 13-16 kPa, the bottom temperature is controlled at 40-45°C, the bottom pressure is controlled at 18-22 kPa, and the bottom temperature is controlled at 77-82°C. Preferably, the light component distillation column adopts azeotropic distillation, and the mass ratio of azeotropic agent to crude acrylic acid reaction liquid feed is 2:1-4:1; preferably, the azeotropic agent is toluene; Preferably, the crude acrylic acid stream after distillation in the light component distillation column enters the acetic acid removal column to remove acetic acid. The pressure at the top of the column is controlled at 4-6 kPa and the temperature is controlled at 50-60°C; the pressure at the bottom of the column is controlled at 9-12 kPa and the temperature is controlled at 77-85°C.

4. The preparation method according to any one of claims 1-3, characterized in that, Acetic acid after acetic acid removal in the deacetic acid tower can be selectively fed into an acid purification tower to remove heavy component impurities. Preferably, the pressure at the top of the acid purification tower is controlled at 2-4 kPa, the temperature is controlled at 48-55°C, the pressure at the bottom of the tower is controlled at 6-8 kPa, and the temperature is controlled at 75-80°C.

5. The preparation method according to any one of claims 1-4, characterized in that, The crude acrylic acid reaction solution also contains the auxiliary agents 2,4-dimethyldithiocarbamate copper and phenothiazine, with the mass ratio of 2,4-dimethyldithiocarbamate copper to phenothiazine being 1:(5-100), more preferably 1:(5-20). Preferably, the amount of phenothiazine added to the crude acrylic acid reaction solution is 0.05-0.12 wt% of the mass of the crude acrylic acid reaction solution.

6. The preparation method according to any one of claims 1-5, characterized in that, The butyl acrylate is obtained by esterification reaction of acrylic acid and n-butanol, and the butyl acrylate product is obtained after removing impurities through a separation process. Preferably, the esterification reaction temperature of the butyl acrylate is 35-53 kPa, and the temperature is 92-98°C; Preferably, the molar ratio of butanol to acrylic acid is 1.1-1.3:1; Preferably, the esterification reaction uses an acid as a catalyst, and the acid catalyst is one or more of p-toluenesulfonic acid or methanesulfonic acid; Preferably, the amount of acid catalyst used is 0.5%-2wt% of the total mass of the esterification reaction raw materials acrylic acid and n-butanol.

7. The preparation method according to any one of claims 1-6, characterized in that, The butyl acrylate separation process includes catalyst extraction and recovery, neutralization and washing, alcohol decanting tower, ester purification tower and heavy component recovery system; Preferably, the extraction and recovery step uses water as the extractant to extract the catalyst from the crude ester after esterification into the aqueous phase, which is then sent to the esterification reactor for recycling. The ratio of extractant to crude ester is 0.5-2:

15. Preferably, the neutralization and washing step involves neutralizing and washing the crude ester with NaOH solution, neutralizing the incompletely reacted acrylic acid to generate sodium acrylate, which is then removed into the wastewater. Preferably, the alcohol top column is a light component separation column. After extraction, neutralization and washing, the crude ester enters the alcohol top column, and the light component impurities are removed to the top of the column and recycled back to the reaction system. Preferably, the ester purification tower is a heavy component removal tower. After removing light components, the crude ester enters the ester purification tower to remove heavy component impurities, thereby obtaining butyl ester product. The removed heavy component impurities enter the heavy component recovery system for decomposition and recovery.

8. The preparation method according to claim 7, characterized in that, The butyl ester heavy component recovery system incorporates an acid catalyst, including one or more of methanesulfonic acid and p-toluenesulfonic acid, wherein the amount of acid catalyst added is 0.5%-5% of the total mass of the system, more preferably 0.6%-2%. Preferably, the temperature of the butyl ester recombination and decomposition system is controlled at 170℃-220℃, more preferably 175℃-200℃; the pressure is 80Kpaa-101.3Kpaa, more preferably 90Kpaa-101.3Kpaa; and the residence time is 2-10h, more preferably 4-8h.

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