System and method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate

Abstract

This invention discloses a system and method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate. The system includes a reaction unit, a separation unit, and a product tank connected in sequence, as well as a dynamic dehydration unit that forms a loop with the reaction unit through pipelines and pumps, a catalyst regeneration unit connected to the organic phase outlet of the heating unit, and a circulating dehydration unit connected between the catalyst regeneration unit and the reaction unit. The method employs a carbonyl metal catalytic system, using a bypass molecular sieve to dynamically adsorb the self-condensing water of the reaction. After separating the aldehyde product, the remaining organic phase is deeply dehydrated by the molecular sieve and recycled. This invention reduces the water content in the reaction system by setting up a closed-loop dehydration system throughout the entire process. Through the combined strategy of "dynamic adsorption by molecular sieve + deep dehydration of the circulating phase," it achieves multiple benefits, including "reduced corrosion, reduced highly toxic byproducts, and increased yield."

Description

Technical Field

[0001] This invention belongs to the field of carbonyl synthesis technology of olefin derivatives, specifically relating to a system and method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate. Background Technology

[0002] 4-Acetoxybutyraldehyde, a key intermediate in the synthesis of 1,4-butanediol (BDO) from propylene and acetic acid, is crucial for the efficient preparation of poly(polyester plastics) (PBT) and spandex fibers. Currently, the mainstream preparation process for 4-acetoxybutyraldehyde employs the allyl acetate hydroformylation method, where it reacts with syngas in the presence of a carbonyl metal catalyst (such as a rhodium-phosphine complex) to generate the target product, 4-acetoxybutyraldehyde. While the allyl acetate hydroformylation method is considered an ideal route for BDO production due to its high atom economy, its industrialization has long been constrained by systemic risks arising from side reaction chains. The core issue is that the water generated during the self-condensation of 4-acetoxybutyraldehyde triggers the hydrolysis of allyl acetate, producing corrosive acetic acid and highly toxic allyl alcohol. Acetic acid increases equipment corrosion rates by 3-5 times and reduces the stability of the catalytic system.

[0003] Although patent CN115286503B points out that allyl alcohol impurities can trigger hydrogenolysis side reactions and proposes a technical solution to control the allyl alcohol / allyl ether ratio (10-200):1 through allyl acetate purification or water washing, this patent only focuses on static impurity management at the raw material end and does not address the dynamic hydrolysis problem caused by the continuous water production from the self-condensation of 4-acetoxybutyraldehyde during the reaction process. The continuously generated free water reacts with allyl acetate to irreversibly generate corrosive acetic acid and highly toxic allyl alcohol, a process that cannot be blocked by raw material pre-purification. Therefore, there is an urgent need to develop a process dehydration mechanism embedded in the production system to inhibit the occurrence of hydrolysis reactions. Summary of the Invention

[0004] This invention addresses the problem in the prior art where the water generated by the self-condensation of 4-acetoxybutyraldehyde leads to the hydrolysis of allyl acetate, resulting in equipment corrosion, raw material loss, and reduced product yield. The purpose is to provide a system and method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate.

[0005] This invention is achieved through the following technical solution:

[0006] A system for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate includes a reaction unit, a separation unit, and a product tank connected in sequence. The separation unit includes a heating unit connected to the bottom outlet of the reaction unit and a condensation and collection unit connected to the gas outlet of the heating unit. The outlet of the condensation and collection unit is connected to the product tank. The system also includes a dynamic dehydration unit that forms a loop with the reaction unit through pipelines and pumps, a catalyst regeneration unit connected to the organic phase outlet of the heating unit, and a circulating dehydration unit connected between the catalyst regeneration unit and the reaction unit.

[0007] In the above technical solution, the reaction unit is respectively provided with a synthesis gas inlet, an allyl acetate inlet, a catalyst feeding port, a circulation outlet, and a circulation inlet.

[0008] In the above technical solution, the top inlet of the dynamic water removal unit is connected to the circulation outlet of the reaction unit through a pipeline and a pump, and the bottom outlet of the dynamic water removal unit is connected to the circulation inlet of the reaction unit through a pipeline and a pump.

[0009] In the above technical solution, the dynamic water removal unit is filled with molecular sieves; the circulating water removal unit is filled with molecular sieves; the molecular sieves are alkali metal aluminosilicate molecular sieves with pore sizes of 0.3nm~0.8nm.

[0010] A method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate according to the aforementioned system includes the following steps:

[0011] S1. The catalyst solution, allyl acetate, and syngas are introduced into the reaction unit respectively. Under the action of the catalytic system, allyl acetate and syngas undergo hydroformylation to generate 4-acetoxybutyraldehyde.

[0012] S2. Turn on the pump between the reaction unit and the dynamic dehydration unit to pump the reaction liquid in the reaction unit to the dynamic dehydration unit, and then return it to the reaction unit from the dynamic dehydration unit to form a cycle.

[0013] S3. After the reaction in the reaction unit is completed, the reaction liquid in the reaction unit is introduced into the separation unit, and after being processed by the heating unit and the condensation and collection unit, the 4-acetoxybutyraldehyde product is obtained.

[0014] S4. The remaining organic phase containing the catalytic system in the heating unit enters the catalyst regeneration unit for activation and regeneration;

[0015] S5. After activation, the organic phase containing the catalytic system enters the circulating dehydration unit to further remove water, and then is recycled back to the reaction unit.

[0016] In the above technical solution, the reaction temperature of the reaction unit is 60℃~200℃, and the reaction pressure is 0.5MPa~10MPa;

[0017] The synthesis gas is a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen to carbon monoxide of (0.5~4):1;

[0018] The molar ratio of allyl acetate to syngas is (0.1~2):1;

[0019] The concentration of the catalyst in the reaction system (reaction unit) is 60ppm to 5000ppm.

[0020] In the above technical solution, the catalyst is a rhodium carbonyl catalyst, a cobalt carbonyl catalyst, a catalytic system in which a rhodium carbonyl catalyst is coordinated with an organic ligand, or a catalytic system in which a cobalt carbonyl catalyst is coordinated with an organic ligand.

[0021] The organic ligand is a phosphine ligand or a nitrogen-containing ligand; the phosphine ligand is an alkylphosphine, arylphosphine, or a phosphonite ester; the nitrogen-containing ligand is a monodentate nitrogen-containing ligand, a bidentate nitrogen-containing ligand, or a multidentate nitrogen-containing ligand;

[0022] The concentration of rhodium or cobalt in the catalyst solution is 60 ppm to 15000 ppm;

[0023] When the catalyst is a catalytic system of a rhodium carbonyl catalyst coordinated with an organic ligand or a cobalt carbonyl catalyst coordinated with an organic ligand, the concentration of the organic ligand in the catalyst solution is 0.5-60%; the solvent of the catalyst solution is 4-acetoxybutyraldehyde.

[0024] In the above technical solution, the temperature of the heating unit is 80℃~200℃ and the pressure is 0.00001MPa~2MPa; the cooling temperature of the condensation collection unit is 0℃~150℃ and the pressure is 0.01MPa~2MPa.

[0025] In the above technical solution, the activation conditions of the catalyst regeneration unit are as follows: the same synthesis gas as in step S1 is introduced into the catalyst regeneration unit, and the reaction temperature of the catalyst regeneration unit is set to 60℃~200℃ and the reaction pressure is 0.5MPa~20MPa.

[0026] In the above technical solution, the dynamic water removal unit and the circulating water removal unit are filled with molecular sieves; the molecular sieves are alkali metal aluminosilicate molecular sieves with a pore size of 0.3nm~0.8nm.

[0027] The beneficial effects of this invention are:

[0028] This invention provides a system and method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate. By using a molecular sieve for real-time dehydration in the reactor bypass and recycling the remaining organic phase back to the reactor after dehydration by a molecular sieve dehydrator, a closed-loop dehydration system is formed. This effectively reduces the water content in the reaction system, controlling it to ≤200 ppm, and achieving a hydrolysis product yield of ≤0.5%. This significantly blocks the hydrolysis-corrosion-hydrogenolysis side reaction chain, interrupting the hydrolysis chain at the process level. Simultaneously, it achieves multiple benefits: reduced corrosion, reduced highly toxic byproducts, and increased yield. This ensures the stability of allyl acetate, reduces the formation of acetic acid and allyl alcohol, lowers equipment corrosion risks and safety hazards, and increases the yield of 4-acetoxybutyraldehyde, ensuring production stability and safety. This improves the economic efficiency of production and has good prospects for industrial application. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate according to the present invention.

[0030] in:

[0031] 1. Reaction unit; 2. Dynamic dehydration unit; 3. Separation unit; 31. Heating unit; 32. Condensation and collection unit; 4. Product tank; 5. Catalyst regeneration unit; 6. Circulating dehydration unit.

[0032] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0034] like Figure 1 As shown, a system for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate includes a reaction unit 1, a separation unit 3 and a product tank 4 connected in sequence. The separation unit 3 includes a heating unit 31 connected to the bottom outlet of the reaction unit 1 and a condensation and collection unit 32 connected to the gas outlet of the heating unit 31. The outlet of the condensation and collection unit 32 is connected to the product tank 4.

[0035] It also includes a dynamic dehydration unit 2 that forms a loop with the reaction unit 1 through pipelines and pumps, a catalyst regeneration unit 5 that is connected to the organic phase outlet of the heating unit 31, and a circulating dehydration unit 6 that is connected between the catalyst regeneration unit 5 and the reaction unit 1.

[0036] The reaction unit 1 is used to contain allyl acetate, syngas, and a catalytic system for reaction.

[0037] The reaction unit 1 is equipped with a synthesis gas inlet, an allyl acetate inlet, a catalyst feeding port, a circulation outlet, and a circulation inlet;

[0038] The top inlet of the dynamic water removal unit 2 is connected to the circulation outlet of the reaction unit 1 through a pipeline and a pump, and the bottom outlet of the dynamic water removal unit 2 is connected to the circulation inlet of the reaction unit 1 through a pipeline and a pump.

[0039] The dynamic dehydration unit 2 is filled with molecular sieves; the reaction unit 1 and the dynamic dehydration unit 2 form a bypass loop. During the reaction process, the reaction liquid of the reaction unit 1 enters the dynamic dehydration unit 2. The molecular sieves can adsorb water in the reaction liquid in real time. The dehydrated reaction liquid is returned to the reaction unit 1 through the pipeline, realizing dynamic dehydration, effectively reducing the water content in the reaction system, inhibiting the hydrolysis of allyl acetate, and reducing the generation of acetic acid and allyl alcohol.

[0040] The separation unit 3 is used to separate the reaction liquid discharged from the reaction unit 1 to achieve the separation of 4-acetoxybutyraldehyde product and catalytic system;

[0041] The heating unit 31 is used to convert the 4-acetoxybutyraldehyde liquid product in the reaction solution into a gas, thereby separating it from the catalytic system.

[0042] The temperature and pressure settings of the heating unit 31 are: temperature of 80℃~200℃ and pressure of 0.00001MPa~2MPa;

[0043] The condensation and collection unit 32 is used to condense the separated 4-acetoxybutyraldehyde product.

[0044] The temperature and pressure settings of the condensation collection unit 32 are: cooling temperature of 0℃~150℃ and pressure of 0.01MPa~2MPa.

[0045] The product tank 4 is used to collect the 4-acetoxybutyraldehyde liquid product obtained from the condensation collection unit 32;

[0046] The catalyst regeneration unit 5 is used to activate the organic phase containing the catalyst system obtained from the organic phase outlet of the condensation and collection unit 32;

[0047] The catalyst regeneration unit 5 can be a reaction vessel. The catalyst regeneration unit 5 is equipped with a synthesis gas inlet. The synthesis gas is introduced into the catalyst regeneration unit 5 and reacts with the organic phase containing the catalyst system obtained from the organic phase outlet of the condensation and collection unit 32 to activate the catalyst.

[0048] The circulating dehydration unit 6 is used to dehydrate the organic phase containing the catalyst system after activation by the catalyst regeneration unit 5. The outlet of the circulating dehydration unit 6 is connected to the reactor, so that the dehydrated organic phase containing the catalyst system is recycled back to the reactor, realizing the recycling of the catalyst system.

[0049] The circulating water removal unit 6 can use the same equipment as the dynamic water removal unit 2, such as conventional filters that can remove water, like bar screens.

[0050] A method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate includes the following steps:

[0051] S1. The catalyst solution, allyl acetate and syngas are introduced into reaction unit 1 respectively. The temperature of reaction unit 1 is controlled to reach the reaction temperature. Allyl acetate and syngas undergo hydroformylation under the action of the catalytic system to generate 4-acetoxybutyraldehyde.

[0052] The reaction temperature of the reaction unit 1 is 60℃~200℃, and the reaction pressure is 0.5MPa~10MPa. Preferably, the reaction temperature is 90℃~180℃, and the reaction pressure is 2MPa~9MPa.

[0053] The synthesis gas is a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen to carbon monoxide of (0.5~4):1;

[0054] The catalyst is a rhodium carbonyl catalyst, a cobalt carbonyl catalyst, a catalytic system in which a rhodium carbonyl catalyst is coordinated with an organic ligand, or a catalytic system in which a cobalt carbonyl catalyst is coordinated with an organic ligand.

[0055] The organic ligand is a phosphine ligand or a nitrogen-containing ligand;

[0056] The phosphine ligand is an alkylphosphine, arylphosphine, or a phosphonite ester;

[0057] The alkylphosphine is trimethylphosphine, triethylphosphine, tri-n-butylphosphine, trihexylphosphine, or tri-n-octylphosphine, etc.

[0058] The arylphosphine is triphenylphosphine, diphenylphosphine, 4-methoxytriphenylphosphine, 2-diphenylphosphinobiphenyl, or 1,3-bis(diphenylphosphino)ethane, etc.

[0059] The phosphonite is triphenylphosphonite, triethyl phosphite, tributyl phosphite, 2-diphenylphosphoxy-1,1'-binaphthyl or tris(2,4-di-tert-butylphenyl) phosphite, etc.

[0060] The nitrogen-containing ligands are monodentate nitrogen-containing ligands, bidentate nitrogen-containing ligands, and multidentate nitrogen-containing ligands;

[0061] The monodentate nitrogen-containing ligand is ammonia, pyridine, methylamine, or pyrrole, etc.

[0062] The bidentate nitrogen-containing ligand is ethylenediamine, o-phenanthroline, 2,2'-bipyridine, 8-hydroxyquinoline, or 1,10-phenanthroline, etc.

[0063] The multidentate nitrogen-containing ligand is ethylenediaminetetraacetic acid, diethylenetriamine, triethylenetetraamine or porphyrin, 1,4,7,10-tetraazacyclododecane (cyclododecanetetraamine), etc.

[0064] The carbonyl rhodium catalyst is rhodium acetylacetone dicarbonyl, rhodium trichloride-carbon monoxide complex, or octacarbonyl dihodium, etc.

[0065] The cobalt carbonyl catalyst is cobalt octacarbonyldicobalt, cobalt tetracarbonyl hydrogen salt, or cobalt hexadecylcarbonylhexacobalt, etc.

[0066] The preparation methods of the rhodium carbonyl catalyst, cobalt carbonyl catalyst, catalytic system of rhodium carbonyl catalyst coordinated with organic ligand or catalytic system of cobalt carbonyl catalyst coordinated with organic ligand are based on CN118289825A, CN111333683B, CN106674285B, and CN102391310B.

[0067] The concentration of rhodium or cobalt in the catalyst solution is 60 ppm to 15000 ppm;

[0068] When the catalyst is a catalytic system of rhodium carbonyl catalyst coordinated with organic ligands or a cobalt carbonyl catalyst coordinated with organic ligands, the concentration of organic ligands in the catalyst solution is 0.5% to 60%.

[0069] The solvent of the catalyst solution is 4-acetoxybutyraldehyde. The target product is used as the solvent of the catalyst solution because the reaction liquid in the reaction unit 1 of the preparation process needs to be introduced into the heating unit 31 of the separation unit 3 for heating to turn the 4-acetoxybutyraldehyde liquid product in the reaction liquid into gas. If other solvents are used as the solvent of the catalyst solution, other impurities will be present in the gas generated by the heating unit 31, affecting the purity of the final product.

[0070] The molar ratio of allyl acetate to syngas is (0.1~2):1;

[0071] The concentration of the catalyst in the reaction system is 60ppm to 5000ppm.

[0072] S2. Turn on the pump between reaction unit 1 and dynamic water removal unit 2 to pump the reaction liquid in reaction unit 1 to dynamic water removal unit 2 to adsorb water, and then return it from dynamic water removal unit 2 to reaction unit 1, thereby reducing the water content in the reaction system in real time.

[0073] After the catalyst solution is introduced, the pump can be turned on for water removal and circulation. Alternatively, depending on economic considerations, the pump can be turned on after a period of reaction. The specific time to turn on the pump does not affect the reaction effect.

[0074] S3. After the reaction in reaction unit 1 is completed, the reaction liquid in reaction unit 1 is introduced into separation unit 3. After being processed by heating unit 31 and condensation and collection unit 32, 4-acetoxybutyraldehyde product is obtained by separation.

[0075] The temperature of the heating unit 31 is set to 80℃~200℃, and the pressure is set to 0.00001MPa~2MPa;

[0076] The cooling temperature of the condensation collection unit 32 is set to 0℃~150℃, and the pressure is set to 0.01MPa~2MPa;

[0077] S4. The remaining organic phase containing the catalytic system in the heating unit 31 enters the catalyst regeneration unit 5 for activation and regeneration.

[0078] The activation conditions for catalyst regeneration unit 5 are as follows: the same synthesis gas as in step S1 is introduced into catalyst regeneration unit 5, the reaction temperature of catalyst regeneration unit 5 is set to 60℃~200℃, the reaction pressure is 0.5MPa~20MPa, and the reaction pressure is achieved by the introduced synthesis gas.

[0079] S5. After the activated organic phase containing the catalytic system enters the circulating dehydration unit 6 to further remove the water, it is recycled back to the reaction unit 1 to realize the recycling of the catalytic system.

[0080] The dynamic water removal unit 2 and the circulating water removal unit 6 are filled with molecular sieves;

[0081] The molecular sieve is an alkali metal aluminosilicate molecular sieve with a pore size of 0.3 nm to 0.8 nm.

[0082] Example 1

[0083] A method for preparing 4-acetoxybutyraldehyde by hydroformylation of allyl acetate includes the following steps:

[0084] S1. The catalyst solution, allyl acetate and syngas are introduced into reaction unit 1 respectively. The temperature of reaction unit 1 is controlled to reach the reaction temperature. Allyl acetate and syngas undergo hydroformylation under the action of the catalytic system to generate 4-acetoxybutyraldehyde.

[0085] The reaction unit 1 is a 5L high-pressure reactor with a built-in stirrer; the stirring speed is 350 r / min.

[0086] The reaction temperature of the reaction unit is 110℃ and the reaction pressure is 4MPa.

[0087] The synthesis gas is a mixture of hydrogen and carbon monoxide, with a molar ratio of hydrogen to carbon monoxide of 1:1; the addition flow rate of the synthesis gas is 30 L / h.

[0088] The catalyst solution uses acetylacetone dicarbonyl rhodium / triphenylphosphine as the active ingredient, wherein the concentration of rhodium is 600 ppm, the concentration of triphenylphosphine is 30%, and the amount of catalyst solution added is 1000 mL.

[0089] The allyl acetate was added at a flow rate of 200 mL / h;

[0090] S2. Turn on the pump between reaction unit 1 and dynamic water removal unit 2 to pump the reaction liquid in reaction unit 1 to dynamic water removal unit 2 to adsorb water, and then return it from dynamic water removal unit 2 to reaction unit 1, thereby reducing the water content in the reaction system in real time.

[0091] The flow rate of the reaction liquid pumped to the dynamic dehydration unit 2 is 1 L / h;

[0092] The molecular sieve in the dynamic dewatering unit 2 is an alkali metal aluminosilicate molecular sieve with a wavelength of 0.3 nm to 0.8 nm.

[0093] S3. After the reaction in reaction unit 1 is completed, the reaction liquid in reaction unit 1 is introduced into separation unit 3. After being processed by heating unit 31 and condensation and collection unit 32, 4-acetoxybutyraldehyde product is obtained by separation.

[0094] The temperature and pressure of the heating unit 31 are set to 120℃ and 0.2MPa;

[0095] The temperature and pressure settings of the condensation collection unit 32 are set to a cooling temperature of 20°C and a pressure of 0.1 MPa.

[0096] S4. The remaining catalyst-containing organic phase in the heating unit 31 enters the catalyst regeneration unit 5 for activation and regeneration.

[0097] The activation and regeneration conditions are set at 180°C and 8 MPa.

[0098] S5. After the activated catalyst-containing organic phase enters the circulating dehydration unit 6 to further remove water, it is recycled back to the reaction unit 1 to realize the recycling of the catalyst.

[0099] The molecular sieve in the circulating dewatering unit 6 is an alkali metal aluminosilicate molecular sieve with a wavelength of 0.3 nm to 0.8 nm.

[0100] A 500-hour long-term evaluation was conducted, and the average yield of 4-acetoxybutyraldehyde was 85%, with a water content of less than 200 ppm in the reaction system.

[0101] Comparative Example 1

[0102] The conditions were the same as in Example 1, except that step S2 was omitted, i.e., the dynamic water removal unit 2 was not set up; a long-term evaluation of 500 hours was conducted, and the average yield of 4-acetoxybutyraldehyde was 76%, with the highest water content in the reaction system being 2%.

[0103] Example 2

[0104] The conditions were the same as in Example 1, except that the catalyst system components were different. The catalyst system in this example was octacarbonyl dicobalt and triphenylphosphine. After a long-term evaluation of 500 hours, the average yield of 4-acetoxybutyraldehyde was 80%, and the water content in the reaction system was less than 200 ppm.

[0105] Comparative Example 2

[0106] The conditions were the same as in Example 2, except that step S2 was omitted, i.e., the dynamic water removal unit 2 was not set up; a long-term evaluation of 500 hours was conducted, and the average yield of 4-acetoxybutyraldehyde was 71%, with the highest water content in the reaction system being 3%.

[0107] This invention reduces the water content in the reaction system by setting up a closed-loop dehydration system throughout the entire process. Through a combination strategy of "dynamic adsorption by molecular sieves + deep dehydration of the circulating phase", the water content of the system is controlled to ≤200ppm, which blocks the hydrolysis chain at the process level. At the same time, it achieves multiple effects such as "reducing corrosion, reducing highly toxic by-products, and increasing yield", which improves the stability of allyl acetate, reduces the formation of acetic acid and allyl alcohol, increases the yield of 4-acetoxybutyraldehyde, and ensures the stability and safety of production.

[0108] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A system for the hydroformylation of allyl acetate to produce 4-acetoxybutyraldehyde, comprising a reaction unit (1), a separation unit (3) and a product tank (4) connected in sequence, the separation unit (3) comprising a heating unit (31) connected to the bottom outlet of the reaction unit (1) and a condensation collection unit (32) connected to the gas outlet of the heating unit (31), the outlet of the condensation collection unit (32) being connected to the product tank (4), characterized in that: It also comprises a dynamic water removal unit (2) connected with the reaction unit (1) through pipes and pumps, a catalyst regeneration unit (5) connected with the organic phase outlet of the heating unit (31), and a circulating water removal unit (6) connected between the catalyst regeneration unit (5) and the reaction unit (1); The dynamic water removal unit (2) is filled with molecular sieves, and the circulating water removal unit (6) is also filled with molecular sieves; the molecular sieves are alkali metal aluminosilicate molecular sieves with a pore size of 0.3-0.8 nm.

2. The system for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 1, characterized in that: The reaction unit (1) is provided with a synthesis gas inlet, an allyl acetate inlet, a catalyst feeding port, a circulating outlet and a circulating inlet, respectively.

3. The system for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 1, characterized in that: The top inlet of the dynamic water removal unit (2) is communicated with the circulating outlet of the reaction unit (1) through pipes and pumps, and the bottom outlet of the dynamic water removal unit (2) is communicated with the circulating inlet of the reaction unit (1) through pipes and pumps.

4. A process for the production of 4-acetoxybutyraldehyde by hydroformylation of allyl acetate using the system according to any one of claims 1 to 3, characterized in that: It comprises the following steps: S1, the catalyst solution, allyl acetate and synthesis gas are respectively introduced into the reaction unit (1), and the allyl acetate and synthesis gas undergo hydroformylation reaction under the action of the catalyst system to generate 4-acetoxybutyraldehyde; S2, the pump between the reaction unit (1) and the dynamic water removal unit (2) is opened, and the reaction liquid in the reaction unit (1) is pumped to the dynamic water removal unit (2) and then returned to the reaction unit (1) from the dynamic water removal unit (2) to form a circulation; S3, after the reaction in the reaction unit (1) is completed, the reaction liquid in the reaction unit (1) is introduced into the separation unit (3), treated by the heating unit (31) and the condensation collection unit (32), and 4-acetoxybutyraldehyde product is separated and obtained; S4, the remaining organic phase containing the catalyst system in the heating unit (31) enters the catalyst regeneration unit (5) for activation and regeneration; S5, after the activated organic phase containing the catalyst system enters the circulating water removal unit (6) to further remove the water therein, it is circulated back to the reaction unit (1).

5. The process for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 4, characterized in that: The reaction temperature of the reaction unit (1) is 60-200℃, and the reaction pressure is 0.5-10 MPa; The synthesis gas is a mixture of hydrogen and carbon monoxide, and the molar ratio of hydrogen to carbon monoxide is (0.5-4):1; The molar ratio of allyl acetate to synthesis gas is (0.1-2):1; The concentration of the catalyst in the reaction system is 60-5000 ppm.

6. The process for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 4, characterized in that: The catalyst is a rhodium carbonyl catalyst, a cobalt carbonyl catalyst, a catalyst system of rhodium carbonyl catalyst coordinated with an organic ligand, or a catalyst system of cobalt carbonyl catalyst coordinated with an organic ligand; The organic ligand is a phosphine ligand or a nitrogen-containing ligand; the phosphine ligand is an alkyl phosphine, an aryl phosphine or a phosphinate; the nitrogen-containing ligand is a monodentate nitrogen-containing ligand, a bidentate nitrogen-containing ligand and a polydentate nitrogen-containing ligand; The concentration of rhodium or cobalt in the catalyst solution is 60-15000 ppm; When the catalyst is a catalyst system of rhodium carbonyl catalyst coordinated with an organic ligand or a catalyst system of cobalt carbonyl catalyst coordinated with an organic ligand, the concentration of the organic ligand in the catalyst solution is 0.5-60%; The solvent of the catalyst solution is 4-acetoxybutyraldehyde.

7. The process for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 4, characterized in that: The temperature of the heating unit (31) is 80-200 DEG C, and the pressure is 0.00001-2 MPa; the cooling temperature of the condensing collection unit (32) is 0-150 DEG C, and the pressure is 0.01-2 MPa.

8. The process for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 4, characterized in that: The activation conditions of the catalyst regeneration unit (5) are as follows: the same synthesis gas as in step S1 is introduced into the catalyst regeneration unit (5), the reaction temperature of the catalyst regeneration unit (5) is set to 60-200 DEG C, and the reaction pressure is set to 0.5-20 MPa.

9. The process for the hydroformylation of allyl acetate to 4-acetoxybutyraldehyde according to claim 4, characterized in that: The dynamic water removal unit (2) and the circulating water removal unit (6) are filled with molecular sieves; the molecular sieves are alkali metal aluminosilicate molecular sieves with a pore size of 0.3-0.8 nm.

Images