Method and device for preparing acetoxypropionaldehyde from vinyl acetate and application of acetoxypropionaldehyde

Abstract

The invention provides a method and device for preparing aldehyde compounds from vinyl acetate and application, and belongs to the field of aldehyde preparation. A part of liquid-phase components obtained by the first reaction unit are cooled and then circulated back to the first reaction unit to control the reaction temperature, and a catalyst solution separated from liquid-phase components obtained by the second reaction unit is circulated back to the first reaction unit and the second reaction unit. According to the aldehyde synthesis method provided by the invention, the return amount of the catalyst solvent can be controlled, the catalyst concentrations of the two reaction zones are respectively regulated, and the retention time and the reaction effect are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of aldehyde compounds, and specifically relates to a method, a device and an application of preparing acetoxypropionaldehyde from vinyl acetate. Background Art

[0002] Polytrimethylene terephthalate (PTT) synthesized from 1,3-propylene glycol shows a faster crystallization rate than polyethylene terephthalate (PET) and a higher heat resistance temperature than polybutylene terephthalate (PBT). It is considered to be a new polyester material that combines the high performance of PET and the easy processing of PBT. In the market, 1,2-propylene glycol has been mass-produced in the 1990s, while 1,3-propylene glycol was considered a scarce specialty chemical until the beginning of this century due to the lack of a feasible process. There are two main industrial processes for 1,3-propylene glycol, namely the acrolein hydration hydrogenation process developed by Evonik (formerly Degussa) in Germany, the hydroformylation ethylene oxide (EO) process developed by Shell, and the production process developed by DuPont that uses enzymes to catalyze sugar compounds to produce 1,3-propylene glycol. The acrolein hydration hydrogenation method has mild conditions and is not technically difficult. The hydrogenation process is relatively mature and the equipment requirements are not high. However, the raw material acrolein of this route is highly toxic, flammable and explosive, difficult to store and transport, and difficult to obtain at a high price. It is more suitable for companies that have acrolein raw materials. The ethylene oxide hydroformylation method has low production costs and mature technology, but the reaction requires high pressure, large equipment investment, high technical difficulty, complex catalytic system, harsh and unstable process, highly toxic ligands, flammable and explosive raw material ethylene oxide, difficult to transport, and difficult to control the reaction. Due to low production efficiency and complex purification process, the bio-enzyme catalysis method does not show higher advantages than the chemical method.

[0003] In the vinyl acetate method, vinyl acetate is first hydroformylated to generate the intermediate product acetoxypropionaldehyde, then hydrogenated to generate acetoxypropanol, and then hydrolyzed to obtain 1,3-propylene glycol and 1,2-propylene glycol, with acetic acid as a by-product. In this process flow, the hydroformylation of vinyl acetate is a key step. In order to improve the conversion rate of the raw materials, the reaction generally uses two or more reactors in series. When heavier substances such as o-dichlorobenzene are used as solvents, the boiling point is high, the boiling point difference is small, the number of separation plates increases, the reflux ratio increases, and the energy consumption increases. When lighter substances such as toluene are used as solvents, the boiling point is light and it is easy to be entrained by the exhaust gas, resulting in solvent loss. After the solvent gas phase is evaporated, the liquid phase needs to be recycled, which increases energy consumption. Summary of the invention

[0004] The invention provides a method for preparing acetoxypropionaldehyde from vinyl acetate. The method can save material consumption, control the return amount of catalyst solution and respectively regulate the catalyst concentrations of two reaction zones during the preparation process, thereby ensuring the residence time and reaction effect.

[0005] One of the purposes of the present invention is to provide a method for preparing acetoxypropionaldehyde from vinyl acetate, comprising: recycling part of the liquid product obtained by reacting vinyl acetate, synthesis gas, catalyst and solvent in a first reaction unit to the first reaction unit, sending the remaining liquid product to a second reaction unit for further reaction, separating the liquid components after the reaction into a crude acetoxypropionaldehyde product and a catalyst solution, and then recycling the obtained catalyst solution to the first reaction unit and the second reaction unit.

[0006] According to the present invention, the method for preparing acetoxypropionaldehyde from vinyl acetate specifically comprises the following steps:

[0007] 1) Vinyl acetate, synthesis gas S1, catalyst and solvent are sent to a first reaction unit for contact reaction, and the obtained gas phase component G1 is sent to a first separation unit;

[0008] 2) The liquid component L1 obtained after the reaction in the first reaction unit is divided into two parts, one part of the liquid component L1-1 is sent to the second reaction unit for further reaction, and the other part of the liquid component L1-2 is circulated to the first reaction unit;

[0009] 3) The liquid component L1-1 and the synthesis gas S2 continue to react in the second reaction unit, and the gas component G2 obtained by the reaction is sent to the first separation unit;

[0010] 4) The liquid component L2 is separated and treated by the first separation unit and the second separation unit to obtain unreacted synthesis gas, crude acetoxypropionaldehyde product and catalyst solution, and a part of the obtained catalyst solution is recycled back to the first reaction unit, and a part is recycled back to the second reaction unit.

[0011] According to a specific embodiment of the present invention, in step 1):

[0012] The synthesis gas S1 can be synthesis gas of various specifications in the art. Preferably, the synthesis gas S1 is a gas component containing hydrogen and carbon monoxide. Preferably, the molar ratio of hydrogen to carbon monoxide in the synthesis gas S1 is (0.3-5):1, preferably (0.5-3):1. In the continuous industrial production process, hydrogen is optionally introduced into the first reaction unit according to the gas composition of the synthesis gas, so as to adjust the ratio of hydrogen to carbon monoxide in the synthesis gas within the above range.

[0013] The molar ratio of vinyl acetate to synthesis gas S1 is 1:(1-25), preferably 1:(1-15), wherein the molar amount of synthesis gas S1 is calculated based on the total molar amount of hydrogen and carbon monoxide therein;

[0014] The catalyst is selected from at least one of the compounds containing the metal component rhodium, and can be a rhodium compound and / or complex commonly used in the art. Further, the catalyst is preferably L-coordinated tricarbonyl rhodium hydride (HRh(CO)3L);

[0015] In terms of molar dosage, the amount of the catalyst is 0.3 to 10 mol%, preferably 0.3 to 5 mol% of vinyl acetate;

[0016] The solvent is selected from at least one of aromatic hydrocarbon solvents and acyloxyaldehyde compounds, preferably at least one of toluene, o-dichlorobenzene, and acetoxypropionaldehyde compounds; according to the present invention, the solvent can be an inert medium such as toluene and o-dichlorobenzene, or a solvent containing acetoxypropionaldehyde compounds, such as 3-acetoxypropionaldehyde, or a mixture containing 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde, wherein the mixture containing 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde can be a reaction product of preparing acetoxypropionaldehyde from vinyl acetate; according to a specific embodiment of the present invention, the solvent is most preferably a solvent containing acetoxypropionaldehyde compounds (3-acetoxypropionaldehyde, or a mixture containing 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde); using a part of the product with a higher boiling point or a part of the crude product as the solvent saves material consumption, reduces the difficulty of separating the crude product from the catalyst solution, and can more flexibly control the concentration of the catalyst solution;

[0017] The catalyst content is 1 to 25 wt %, preferably 10 to 22 wt %, based on the total weight of the catalyst and the solvent;

[0018] The reaction conditions of the first reaction unit are: reaction temperature of 50-150°C, reaction pressure of 0.5-8MPa; preferably, reaction temperature of 80-130°C, reaction pressure of 2-7.5MPa;

[0019] In the step of sending the gas phase component G1 obtained in the first reaction unit to the first separation unit for treatment, the gas phase component G1 can be directly sent to the first separation unit for treatment, or the gas phase component G1 can be first cooled and then subjected to gas-liquid separation, and the liquid phase obtained by separation is sent to the first separation unit for treatment. For example, the liquid phase after gas-liquid separation is cooled to 20-80°C and sent to the first separation unit.

[0020] According to a specific embodiment of the present invention, in step 2):

[0021] The liquid component L1-2 circulated to the first reaction unit accounts for 10 to 90% of the total amount of the liquid component L1, preferably 10 to 50%; preferably, the liquid component L1-2 is cooled and circulated to the first reaction unit to control the reaction temperature of the first reaction unit; further, the temperature of the liquid component L1-2 after cooling is 20 to 100°C, preferably 40 to 100°C.

[0022] According to a specific embodiment of the present invention, in step 3):

[0023] The synthesis gas S2 can be synthesis gas of various specifications in the art. Preferably, the synthesis gas S2 is a gas component containing hydrogen and carbon monoxide. Preferably, the molar ratio of hydrogen to carbon monoxide in the synthesis gas S2 is (0.3-5):1, preferably (0.5-3):1. In the continuous industrial production process, hydrogen is optionally introduced into the second reaction unit according to the gas composition of the synthesis gas, so as to adjust the ratio of hydrogen to carbon monoxide in the synthesis gas within the above range.

[0024] The feed molar ratio of vinyl acetate to synthesis gas S2 in the liquid phase component L1-1 is 1:(1-25), preferably 1:(1-15), wherein the molar amount of synthesis gas S2 is calculated based on the total molar amount of hydrogen and carbon monoxide therein;

[0025] In the second reaction unit, the catalyst is 0.3 to 20 wt %, preferably 1 to 18 wt % of the vinyl acetate in the liquid component L1-1;

[0026] The reaction conditions of the second reaction unit are: reaction temperature of 50-150°C, reaction pressure of 0.5-8MPa; preferably, reaction temperature of 80-130°C, reaction pressure of 2-7.5MPa;

[0027] In the step of sending the gas phase component G2 obtained in the second reaction unit to the first separation unit for treatment, the gas phase component G2 can be directly sent to the first separation unit for treatment, or the gas phase component G2 can be first cooled and then subjected to gas-liquid separation, and the liquid phase obtained by separation is sent to the first separation unit for treatment. For example, the liquid phase after gas-liquid separation is cooled to 20-80°C and sent to the first separation unit.

[0028] According to a specific embodiment of the present invention, in step 4):

[0029] The separation treatment includes flash evaporation of a first separation unit and tower separation of a second separation unit, and the specific operation is: flash evaporation of the gas phase G1 and the gas phase G2 fed into the first separation unit after cooling the liquid phase and the liquid phase L2 to obtain a gas phase component G3 and a liquid phase component L3, wherein the gas phase component G3 mainly contains unreacted synthesis gas, part of low-boiling point by-products such as acetic acid, ethyl acetate, ethylene, etc., and the liquid phase component L3 mainly contains the reaction products 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde, a catalyst, and a solvent, and then the liquid phase component The fraction L3 is further separated by a separation tower to obtain a crude acetoxypropionaldehyde product and a catalyst solution; the flash evaporation and tower separation can adopt the operating equipment and operating conditions commonly used in the art. Preferably, the operating conditions of the first separation unit are: cooling separation at 20 to 80° C., flash evaporation at a pressure of 0.5 to 2.5 MPa and a combination thereof, and the operating conditions of the second separation unit are a tower top temperature of 80 to 120° C., a tower bottom temperature of 90 to 150° C., a pressure of 10 to 200 KPa, and a tower plate number of 5 to 40;

[0030] The catalyst content in the separated catalyst solution is 1 to 30 wt%, preferably 10 to 20 wt%;

[0031] The ratio of the separated catalyst solution circulated to the first reaction unit and the second reaction unit is not particularly limited and can be adjusted within a wide range. Preferably, the catalyst solution circulated to the first reaction unit is 50-99% of the total amount of the separated catalyst solution, preferably 60-99%; the catalyst solution circulated to the second reaction unit is 1-50% of the total amount of the separated catalyst solution, preferably 1-40%; the circulated catalyst can be partially or completely returned to the first reaction unit and the second reaction unit according to actual needs, and the remaining part can be discharged for recovery.

[0032] A second object of the present invention is to provide a device for preparing acetoxypropionaldehyde from vinyl acetate, which is used to implement the above-mentioned method for preparing acetoxypropionaldehyde from vinyl acetate.

[0033] According to the present invention, the device includes a first reaction unit, a second reaction unit, a first separation unit, and a second separation unit. The liquid phase component outlet pipeline of the first reaction unit is connected to the liquid phase material inlet of the second reaction unit, and a branch is arranged on the liquid phase component outlet pipeline of the first reaction unit to be connected to the first reaction unit, the liquid phase outlet pipeline of the second reaction unit is connected to the material inlet of the first separation unit, the liquid phase component outlet of the first separation unit is connected to the material inlet of the second separation unit, and the catalyst solution outlet of the second separation unit is arranged with a pipeline to be connected to the first reaction unit and the second reaction unit.

[0034] According to a specific embodiment of the present invention, in the device:

[0035] The first reaction unit is provided with a raw material inlet and a synthesis gas inlet, and the first reaction unit is optionally provided with a hydrogen inlet; the first reaction unit is provided with a gas phase component outlet, which is connected to the first separation unit by a pipeline; the first reaction unit is provided with a cooling system, preferably a cooling coil; the first reaction unit can be various synthesis reactors known in the art, as long as it can meet the conditions for preparing acetoxypropionaldehyde from vinyl acetate;

[0036] The second reaction unit is provided with a synthesis gas inlet, and the second reaction unit is optionally provided with a hydrogen inlet; the second reaction unit is provided with a gas phase component outlet, and is connected to the first separation unit by a pipeline; the second reaction unit can be various synthesis reactors known in the art, as long as it can meet the conditions for preparing acetoxypropionaldehyde from vinyl acetate;

[0037] The first separation unit is also provided with a non-condensable gas component discharge pipeline. The first separation unit can be any separator known in the art, as long as it can effectively separate the non-condensable gas component from the liquid phase component. For example, the first separation unit can be any vacuum flash gas-liquid separation tank or a combination thereof.

[0038] The second separation unit is provided with a crude product discharge pipeline, and the second separation unit can be a combination of various separation equipment known in the art, as long as it can separate the crude acetoxypropionaldehyde product and the catalyst solution. For example, the second separation unit can be a tower separation equipment.

[0039] A third object of the present invention is to provide the above-mentioned method for preparing acetoxypropionaldehyde from vinyl acetate or the above-mentioned device for preparing acetoxypropionaldehyde from vinyl acetate, and their application in the preparation of acetoxypropionaldehyde.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The device for preparing aldehyde compounds from vinyl acetate provided by the present invention saves energy consumption by setting multiple reaction units and separation units and rationally arranging the material flow direction;

[0042] 2. The method for preparing aldehyde compounds from vinyl acetate provided by the present invention improves the yield of raw material vinyl acetate and ensures the residence time and reaction effect by controlling the circulation ratio of the catalyst solution and regulating the amount of catalyst in different reaction zones;

[0043] 3. The present invention uses a catalyst without using a co-catalyst and a reaction accelerator, simplifies the process, reduces the complexity of the catalyst recycling, and can be widely used in the continuous industrial production of aldehyde compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1This is a schematic diagram of a hydroformylation reaction device used in an embodiment of the present invention.

[0045] Description of reference numerals:

[0046] 1-first reaction unit, 2-second reaction unit, 3-first separation unit, 4-second separation unit, 5-gas component G1 pipeline, 6-gas component G2 pipeline, 7-synthesis gas S1 pipeline, 8-raw material pipeline, 9-hydrogen pipeline, 10-synthesis gas S2 pipeline, 11-liquid component L1-2 circulation pipeline, 12-catalyst solution circulation pipeline, 13-crude product discharge pipeline. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0048] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0049] The hydroformylation reaction device used in the embodiment of the present invention is as follows Figure 1 As shown, the device includes a first reaction unit 1, a second reaction unit 2, a first separation unit 3, and a second separation unit 4. The liquid component outlet pipeline of the first reaction unit 1 is connected to the liquid material L1-1 inlet of the second reaction unit 2, and a branch 11 is arranged on the liquid component outlet pipeline of the first reaction unit 1 to be connected to the first reaction unit, the liquid component L3 outlet pipeline of the second reaction unit 2 is connected to the material inlet of the first separation unit 3, the liquid component L5 outlet of the first separation unit 3 is connected to the material inlet of the second separation unit 4, and the catalyst solution outlet of the second separation unit 4 is connected to the first reaction unit 1 and the second reaction unit 2 by a pipeline 12. Among them, the first reaction unit 1 is provided with a raw material inlet 8, a synthesis gas S1 inlet 7, and a hydrogen inlet 9; the first reaction unit 1 is provided with a gas phase component G1 outlet connected to the first separation unit 3; the second reaction unit 2 is provided with a synthesis gas S2 inlet 10, and a hydrogen inlet 9; the second reaction unit 2 is provided with a gas phase component G2 outlet connected to the first separation unit 3; the first separation unit 3 is also provided with an external discharge pipeline for the non-condensable gas component G3; the second separation unit 4 is provided with a crude product external discharge pipeline 13, and a circulation pipeline 12 for circulating the catalyst solution to the first reaction unit and the second reaction unit.

[0050] The following is combined with Figure 1 The present invention is described in further detail:

[0051] 1) under hydroformylation conditions, vinyl acetate (containing a hydroformylation catalyst) 8, optional hydrogen 9 and synthesis gas S17 are fed into a first reaction unit 1 for contact reaction, and a gas phase component G1 in the reaction product is fed into a first separation unit 3;

[0052] 2) The product liquid phase L1 in the first reaction unit 1 (including the hydroformylation catalyst, the reaction product, and the unreacted reactants) is divided into two parts, one part L1-1 is sent to the second reaction unit 2 for reaction, and the other part L1-2 is circulated back to the first reaction unit 1 as a liquid phase product to control the temperature of the first reaction unit;

[0053] 3) Part of the liquid phase L1-1 of the first reaction unit 1 is fully contacted and reacted with the optional hydrogen 9 and another stream of synthesis gas S210 in the second reaction unit 2 to obtain a gas phase component G2 which is sent to the first separation unit 3 and a liquid phase component L2;

[0054] 4) The product liquid phase L2 obtained from the second reaction unit 2 enters the first separation unit 3, and the unreacted synthesis gas G3 is separated and discharged. The separated liquid phase L3 is sent to the second separation unit 4 for further separation. The separated crude product containing acetoxypropionaldehyde is taken out from the top of the second separation unit 4 and sent to the subsequent process. The catalyst solution 12 taken out from the bottom of the tower is divided into two streams, which are circulated back to the first reaction unit 1 and the second reaction unit 2 respectively.

[0055] Example 1

[0056] Vinyl acetate, synthesis gas S1 and catalyst solution (the solvent is 3-acetoxypropionaldehyde, and the amount of rhodium compound in the solution is 18.46% based on L-coordinated tricarbonyl rhodium hydride) are fed into the first reaction unit 1, wherein the introduction rate of vinyl acetate is 2829 kg / h, the introduction rate of catalyst solution is 756.9 kg / h, and the introduction rate of synthesis gas S1 is 925.2 kg / h (the molar ratio of hydrogen to carbon monoxide in the synthesis gas is 1.02:1), and the feed molar ratio of synthesis gas to vinyl acetate in the reactor is maintained at about 2:1; a part of the bottom liquid phase L1-2 in the first reaction unit 1 is cooled to 45°C and then returned to the first reaction unit 1, and the other part L1-1 is fed to the second reaction unit 2, and the ratio of the liquid phase L1-2 returned to the first reaction unit 1 to the total liquid phase L1 produced from the first reaction unit is 0.12.

[0057] Another stream of synthesis gas S2 (the molar ratio of hydrogen to carbon monoxide in the synthesis gas S2 is 1:1) and part of the liquid phase L1-1 of the first reaction unit 1 are fed into the second reaction unit 2, wherein the feeding rate of the liquid phase L1-1 is 4432.29 kg / h, the feeding rate of the synthesis gas S2 is 102.8 kg / h, and the feeding molar ratio of the synthesis gas S2 of the second reaction unit 2 to the vinyl acetate in L1-1 is maintained at 2:1;

[0058] The gas phase G1 fed into the first reaction unit is combined with the gas phase G2 fed into the second reaction unit, cooled to 39°C, and then subjected to gas-liquid separation. The separated liquid phase and the product liquid phase L2 of the second reaction unit 2 are fed into the first separation unit 3, depressurized to 1.0 MPa for flash evaporation, and the unreacted partial synthesis gas gas phase G3 is separated and discharged, and the liquid phase L3 is fed into the second separation unit 4 for separation;

[0059] The liquid phase component L3 obtained from the first separation unit 3 is sent to the second separation unit 4 (separation tower) for gas-liquid separation, wherein the top temperature of the separation tower is 101.5°C, the bottom temperature is 122.1°C, the pressure is 25kPa, the number of plates is 22, and part of the crude acetoxypropionaldehyde product is refluxed at the top of the tower, and the reflux ratio is 1, so that the crude acetoxypropionaldehyde product is mainly extracted from the top of the tower, and the extraction rate of the crude acetoxypropionaldehyde product is 3647.15kg / h. The catalyst solution is extracted from the bottom of the separation tower, and the extraction rate is 841kg / h. The extracted catalyst solution is partially or completely returned to the first reaction unit 1 and the second reaction unit 2 as a catalyst solution as needed, which are 756.9kg / h and 84.1kg / h respectively, and the remaining part is discharged for recovery.

[0060] The reaction temperature in the first reaction unit 1 and the second reaction unit 2 is 109°C and the pressure is 6.5 MPa. The residence time in the first reaction unit is 70 minutes and the residence time in the second reaction unit is 80 minutes. The conversion rate of vinyl acetate is 99% and the yield is 89.7%.

[0061] Example 2

[0062] The process of Example 1 was followed, except that:

[0063] Vinyl acetate, synthesis gas S1 and catalyst solution (the solvent is o-dichlorobenzene, and the amount of rhodium compound in the solution is 16.8% based on L-coordinated tricarbonyl rhodium hydride) are fed into the first reaction unit 1, wherein the introduction rate of vinyl acetate is 2829 kg / h, the introduction rate of catalyst solution is 789.61 kg / h, and the introduction rate of synthesis gas S1 is 964.8 kg / h (the molar ratio of hydrogen to carbon monoxide in the synthesis gas is 1.02:1), and the feed molar ratio of synthesis gas S1 to vinyl acetate in the reactor is about 2.2:1; a part of the bottom liquid phase L1-2 in the first reaction unit 1 is cooled to 45°C and then returned to the first reaction unit 1, and the other part L1-1 is fed to the second reaction unit 2, and the ratio of the liquid phase L1-2 returned to the first reaction unit 1 to the total liquid phase L1 produced from the first reaction unit is 0.15.

[0064] Another stream of synthesis gas S2 (the molar ratio of hydrogen to carbon monoxide in the synthesis gas S2 is about 1:1) and part of the liquid phase L1-1 of the first reaction unit 1 are fed into the second reaction unit 2, wherein the feeding rate of the liquid phase L1-1 is 4641.83 kg / h, the feeding rate of the synthesis gas S is 110.1 kg / h, and the feeding molar ratio of the synthesis gas S2 of the second reaction unit 2 to the vinyl acetate in L1-1 is 3:1;

[0065] The gas phase G1 fed into the first reaction unit is combined with the gas phase G2 fed into the second reaction unit, cooled to 39°C, and then subjected to gas-liquid separation. The separated liquid phase and the product liquid phase L2 of the second reaction unit 2 are fed into the first separation unit 3, depressurized to 1.2 MPa for flash evaporation, and the unreacted partial synthesis gas gas phase G3 is separated and discharged, and the liquid phase L3 is fed into the second separation unit 4 for separation;

[0066] The liquid phase component L3 obtained by the gas-liquid separation unit 3 is sent to the separation tower for gas-liquid separation, wherein the top temperature of the separation tower is 99.2°C, the bottom temperature is 119.3°C, the pressure is 20kPa, the number of plates is 38), and the reflux ratio is 8, so that the crude product of acetoxypropionaldehyde is mainly extracted from the top of the tower, and the extraction rate of the crude product of acetoxypropionaldehyde is 3839.36kg / h, and the catalyst solution is extracted from the bottom of the separation tower, and the extraction rate is 850kg / h. The extracted catalyst solution is partially or completely returned to the first reaction unit 1 and the second reaction unit 2 as a catalyst solution as needed, which are 841kg / h and 93.44kg / h respectively, and the remaining part is discharged for recovery.

[0067] The reaction temperature in the first reaction unit 1 and the second reaction unit 2 is 113° C. and the pressure is 7 MPa. The conversion rate of vinyl acetate is 99% and the yield is 88.9%.

[0068] Example 3

[0069] Vinyl acetate, synthesis gas S1 and catalyst solution (the solvent is 3-acetoxypropionaldehyde, and the amount of rhodium compound in the solution is 10.22% based on L-coordinated tricarbonyl hydride rhodium) are fed into the first reaction unit 1, wherein the feeding rate of vinyl acetate is 2829 kg / h, the feeding rate of catalyst solution is 774.4 kg / h, and the feeding rate of synthesis gas S1 is 929.7 kg / h (the molar ratio of hydrogen to carbon monoxide in the synthesis gas is 1.09:1), and the feeding molar ratio of synthesis gas to vinyl acetate in the reactor is maintained at about 1.96:1; a part of the bottom liquid phase L1-2 in the first reaction unit 1 is cooled to 45°C and then returned to the first reaction unit 1, and the other part L1-1 is fed to the second reaction unit 2, and the ratio of the liquid phase L1-2 returned to the first reaction unit 1 to the total liquid phase L1 produced from the first reaction unit is 0.12;

[0070] Another stream of synthesis gas S2 (the molar ratio of hydrogen to carbon monoxide in the synthesis gas S2 is 1.09:1) and part of the liquid phase L1-1 of the first reaction unit 1 are fed into the second reaction unit 2, wherein the feeding rate of the liquid phase L1-1 is 4468.29 kg / h, the feeding rate of the synthesis gas S2 is 103.3 kg / h, and the feeding molar ratio of the synthesis gas S2 of the second reaction unit 2 to the vinyl acetate in L1-1 is maintained at 4.8:1;

[0071] The gas phase G1 fed into the first reaction unit is combined with the gas phase G2 fed into the second reaction unit, cooled to 39°C, and then subjected to gas-liquid separation. The separated liquid phase and the product liquid phase L2 of the second reaction unit 2 are fed into the first separation unit 3, depressurized to 1.0 MPa for flash evaporation, and the unreacted partial synthesis gas gas phase G3 is separated and discharged, and the liquid phase L3 is fed into the second separation unit 4 for separation;

[0072] The liquid phase component L3 obtained by the first separation unit 3 is sent to the second separation unit 4 (separation tower) for gas-liquid separation, wherein the top temperature of the separation tower is 101.6°C, the bottom temperature is 122.0°C, the pressure is 30kPa, the number of plates is 22, and part of the crude acetoxypropionaldehyde product is refluxed at the top of the tower, and the reflux ratio is 1, so that the crude acetoxypropionaldehyde product is mainly extracted from the top of the tower, and the extraction rate of the crude acetoxypropionaldehyde product is 3651.94kg / h, and the catalyst solution is extracted from the bottom of the separation tower, and the extraction rate is 880kg / h. The extracted catalyst solution is partially or completely returned to the first reaction unit 1 and the second reaction unit 2 as a catalyst solution as needed, which are 774.4kg / h and 105.6kg / h respectively, and the remaining part is discharged for recovery.

[0073] The reaction temperature in the first reaction unit 1 is 103°C and the pressure is 6.5 MPa, and the reaction temperature in the second reaction unit 2 is 107°C and the pressure is 6.0 MPa. The residence time in the first reaction unit is 50 minutes, and the residence time in the second reaction unit is 70 minutes. The conversion rate of vinyl acetate is 99%, and the yield is 89.6%.

[0074] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing acetoxypropionaldehyde from vinyl acetate, comprising: The liquid product obtained by reacting vinyl acetate, synthesis gas, catalyst and solvent in the first reaction unit is partially recycled to the first reaction unit, and the remaining liquid product is sent to the second reaction unit for further reaction. The liquid components after the reaction are separated into crude acetoxypropionaldehyde product and catalyst solution, and the obtained catalyst solution is recycled to the first reaction unit and the second reaction unit.

2. The method according to claim 1, characterized in that The specific steps include: 1) Vinyl acetate, synthesis gas S1, catalyst and solvent are sent to a first reaction unit for contact reaction, and the obtained gas phase component G1 is sent to a first separation unit; 2) The liquid component L1 obtained after the reaction in the first reaction unit is divided into two parts, one part of the liquid component L1-1 is sent to the second reaction unit for further reaction, and the other part of the liquid component L1-2 is circulated to the first reaction unit; 3) The liquid component L1-1 and the synthesis gas S2 continue to react in the second reaction unit, and the gas component G2 obtained by the reaction is sent to the first separation unit; 4) The liquid component L2 is separated and treated by the first separation unit and the second separation unit to obtain unreacted synthesis gas, crude acetoxypropionaldehyde product and catalyst solution, and a part of the obtained catalyst solution is recycled back to the first reaction unit, and a part is recycled back to the second reaction unit.

3. The method according to claim 2, characterized in that In the step 1): The synthesis gas S1 is a gas component containing hydrogen and carbon monoxide. Preferably, the molar ratio of hydrogen to carbon monoxide in the synthesis gas S1 is (0.3-5):1; and / or, The molar ratio of vinyl acetate to synthesis gas S1 is 1:(1-25), preferably 1:(1-15); and / or, The catalyst is selected from at least one compound containing the metal component rhodium, preferably L-coordinated tricarbonyl rhodium hydride; and / or, In terms of molar dosage, the amount of the catalyst is 0.3 to 10 mol%, preferably 0.3 to 5 mol%, of vinyl acetate; and / or, The solvent is selected from at least one of aromatic hydrocarbon solvents and acyloxyaldehyde compounds, preferably at least one of toluene, o-dichlorobenzene, and acetoxypropionaldehyde compounds; and / or, The catalyst content is 1 to 25 wt%, preferably 10 to 22 wt%, based on the total weight of the catalyst and the solvent; and / or The reaction conditions of the first reaction unit are: reaction temperature of 50-150° C., reaction pressure of 0.5-8 MPa; preferably, reaction temperature of 80-130° C., reaction pressure of 2-7.5 MPa.

4. The method according to claim 2, characterized in that: In the step 2): The liquid phase component L1-2 recycled to the first reaction unit accounts for 10 to 90% of the total amount of the liquid phase component L1, preferably 10 to 50%.

5. The method according to claim 2, characterized in that: In the step 3): The synthesis gas S2 is a gas component containing hydrogen and carbon monoxide. Preferably, the molar ratio of hydrogen to carbon monoxide in the synthesis gas S2 is (0.3-5):1; and / or, The molar ratio of vinyl acetate to synthesis gas S2 in the liquid component L1-1 is 1:(1-25), preferably 1:(1-15); and / or, The reaction conditions of the second reaction unit are: reaction temperature of 50-150° C., reaction pressure of 0.5-8 MPa; preferably, reaction temperature of 80-130° C., reaction pressure of 2-7.5 MPa.

6. The method according to claim 2, characterized in that In the step 4): The catalyst content in the separated catalyst solution is 1 to 30 wt%, preferably 10 to 20 wt%; and / or, The catalyst solution recycled to the first reaction unit is 50-99%, preferably 60-99%, of the total amount of the catalyst solution separated; and / or, The catalyst solution circulated to the second reaction unit is 1 to 50%, preferably 1 to 40%, of the total amount of the separated catalyst solution.

7. An apparatus for preparing acetoxypropionaldehyde from vinyl acetate, used for implementing the method for preparing acetoxypropionaldehyde from vinyl acetate as claimed in any one of claims 1 to 6.

8. The device according to claim 7, characterized in that The device comprises a first reaction unit, a second reaction unit, a first separation unit and a second separation unit, wherein a liquid phase component outlet pipeline of the first reaction unit is connected to a liquid phase material inlet of the second reaction unit, and a branch is arranged on the liquid phase component outlet pipeline of the first reaction unit and connected to the first reaction unit, a liquid phase component outlet pipeline of the second reaction unit is connected to a material inlet of the first separation unit, a liquid phase component outlet of the first separation unit is connected to a material inlet of the second separation unit, and a catalyst solution outlet of the second separation unit is arranged with a pipeline connected to the first reaction unit and the second reaction unit.

9. The device according to claim 8, characterized in that The first reaction unit is provided with a raw material inlet and a synthesis gas inlet; and / or, The first reaction unit is optionally provided with a hydrogen inlet; and / or, The first reaction unit is provided with a gas phase component outlet, which is connected to the first separation unit via a pipeline; and / or, The second reaction unit is provided with a gas phase component outlet, which is connected to the first separation unit via a pipeline; and / or, The first reaction unit is provided with a cooling system, preferably a cooling coil; and / or, The second reaction unit is provided with a synthesis gas inlet; and / or, The second reaction unit is optionally provided with a hydrogen inlet; and / or, The first separation unit is further provided with a non-condensable gas component discharge pipeline; and / or, The second separation unit is also provided with a crude product discharge pipeline.

10. Use of the method for preparing acetoxypropionaldehyde from vinyl acetate as claimed in any one of claims 1 to 6 or the device for preparing acetoxypropionaldehyde from vinyl acetate as claimed in any one of claims 7 to 9 in the preparation of acetoxypropionaldehyde.

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