Method for continuously preparing 1, 2-propylene glycol and 1, 3-propylene glycol and application thereof

Abstract

The invention relates to a method for continuously preparing 1, 2-propylene glycol and 1, 3-propylene glycol and application of the method, and belongs to the field of preparation of propylene glycol. In a hydroformylation reaction unit, vinyl acetate, synthesis gas and a first catalyst are subjected to a contact reaction; cooling a part of the hydroformylation reaction product, returning to the hydroformylation reaction to control the reaction temperature, and carrying out pressure reduction on the other part of the reaction product to separate out crude acetoxypropionaldehyde; the crude acetoxypropionaldehyde and hydrogen are subjected to a contact reaction on a second catalyst, water is used as a solvent, the reaction product continues to be subjected to a contact reaction with a third catalyst solution, and 1, 2-propylene glycol, 1, 3-propylene glycol and acetic acid are obtained after separation treatment. The method is safer in raw materials, simple in process, easy to operate, diversified in product composition and high in market adaptability.

Description

Technical Field

[0001] The invention belongs to the technical field of propylene glycol preparation, and specifically relates to a method for continuously preparing 1,2-propylene glycol and 1,3-propylene glycol and an application thereof. Background Art

[0002] Polytrimethylene terephthalate (PTT) synthesized from 1,3-propylene glycol is a new polyester material that combines the high performance of polyethylene terephthalate (PET) and the easy processing of polybutylene terephthalate (PBT). The current mature industrial processes all have their own shortcomings. The raw material acrolein for the acrolein hydration hydrogenation process developed by Evonik (formerly Degussa) in Germany is highly toxic, flammable and explosive, difficult to store and transport, and difficult to obtain at a high price. The hydroformylation ethylene oxide (EO) process developed by Shell requires high-pressure equipment, high technical difficulty, complex catalytic system, harsh and unstable process, and difficult to control the reaction. The bio-enzyme catalysis method developed by Du Pont has low production efficiency and complex purification process. Therefore, the process of synthesizing propylene glycol and hydroxypropionic acid compounds with vinyl acetate hydroformylation as the key step has been widely studied in recent years, and the preparation technology of its catalyst has become increasingly mature. In this process, vinyl acetate is first hydroformylated to produce the intermediate product acetoxypropionaldehyde, which is then hydrogenated to produce acetoxypropanol, and then hydrolyzed to produce 1,3-propylene glycol and 1,2-propylene glycol, with acetic acid as a by-product.

[0003] Using vinyl acetate and synthesis gas as raw materials, a hydroformylation reaction is carried out under the action of a hydroformylation catalyst to obtain crude acetoxypropionaldehyde. Through a hydrogenation catalyst, hydrogen reacts with the acetoxypropionaldehyde therein to obtain acetoxypropanol, which is then hydrolyzed to obtain crude propylene glycol. Further refining obtains high-purity 1,2-propylene glycol and 1,3-propylene glycol products, and produces acetic acid as a by-product. This method has safer raw materials, simple processes, easy operation, diverse product compositions, and strong market adaptability. Summary of the invention

[0004] The invention provides a method for continuously preparing 1,2-propylene glycol and 1,3-propylene glycol by taking vinyl acetate as a raw material. The method has safer raw materials, simple process, easy operation, diverse product composition and strong market adaptability.

[0005] One of the purposes of the present invention is to provide a method for continuously preparing 1,2-propylene glycol and 1,3-propylene glycol, comprising: subjecting vinyl acetate and synthesis gas to a hydroformylation reaction under the action of a catalyst, and then subjecting them to a hydrogenation reaction and a hydrolysis reaction, and refining the products obtained after the hydrolysis to obtain 1,2-propylene glycol and 1,3-propylene glycol; wherein the solvent used in the hydroformylation reaction is an acyloxypropionaldehyde compound, and the solvent used in the hydrogenation reaction is water. According to the present invention, after the hydroformylation reaction, part of the hydroformylation liquid phase product is cooled and returned to the hydroformylation reaction; and the water obtained by separating the products after the hydrolysis reaction is returned to the hydrogenation reaction.

[0006] According to the present invention, the method specifically comprises the following steps:

[0007] (1) vinyl acetate and synthesis gas are contacted with a first catalyst solution C1 to carry out a hydroformylation reaction, a gaseous component obtained by the hydroformylation reaction is discharged, and a liquid component P1 obtained by the hydroformylation reaction is divided into two parts, one part of the liquid component P1-1 is cooled and returned to the hydroformylation reaction, and the remaining liquid component P1-2 is separated by reducing pressure to obtain a first catalyst and solvent S1 or a mixture thereof, and crude acetoxypropionaldehyde, wherein the first catalyst and solvent S1 or a mixture thereof are returned to the hydroformylation reaction;

[0008] (2) subjecting the crude acetoxypropanal, hydrogen and water to a hydrogenation reaction under the action of a second catalyst C2, discharging a gaseous component obtained after the hydrogenation reaction, and obtaining a liquid product containing acetoxypropanol;

[0009] (3) contacting the liquid product containing acetoxypropanol with the third catalyst solution C3 to carry out a hydrolysis reaction, and obtaining the third catalyst and solvent S2 or a mixture thereof, and a hydrolysis reaction product after separation, wherein the third catalyst and solvent S2 or a mixture thereof are recycled to the hydrolysis reaction;

[0010] (4) separating and treating the hydrolysis reaction product obtained in step (3) to obtain water, 1,2-propylene glycol, 1,3-propylene glycol and acetic acid, wherein the separated water is recycled to the hydrogenation reaction.

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

[0012] The first catalyst may be a hydroformylation catalyst commonly used in the art. For example, the first catalyst is selected from at least one of compounds containing metal rhodium and / or cobalt, and may be a compound and / or complex of rhodium and / or cobalt commonly used in the art. Preferably, the first catalyst is selected from at least one of octacarbonyl cobalt and L-coordinated tricarbonyl hydride rhodium (HRh(CO)3L);

[0013] The solvent S1 in the first catalyst solution C1 is an acyloxypropionaldehyde compound, preferably acetoxypropionaldehyde, such as 3-acetoxypropionaldehyde, or a mixture of 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde, wherein the mixture of 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde can be a crude product of a hydroformylation reaction; using the crude product of a hydroformylation reaction as a solvent can avoid the introduction of other substances, improve the separation efficiency of the product and the catalyst solution, and improve the recovery rate;

[0014] The content of the first catalyst in the first catalyst solution C1 can be adjusted within a wide range. For example, the content of the first catalyst in the first catalyst solution C1 is 1 to 23 wt %, preferably 10 to 23 wt %;

[0015] The amount of the first catalyst is within the commonly used amount range in the art and can be adjusted within a wide range. For example, the molar ratio of the vinyl acetate to the first catalyst solution C1 is (1-10):1, preferably (1-8):1, wherein the first catalyst solution C1 is calculated based on the total molar amount of the first catalyst and the solvent;

[0016] The synthesis gas may be any synthesis gas of various specifications commonly used in the art. For example, the synthesis gas contains hydrogen and carbon monoxide. Preferably, the molar ratio of hydrogen to carbon monoxide is (0.3-5):1, preferably (0.5-2):1;

[0017] The molar ratio of vinyl acetate to synthesis gas is 1:(1-21), preferably 1:(1-10).

[0018] According to a specific embodiment of the present invention, in step (1):

[0019] Hydrogen may be optionally introduced into the hydroformylation reaction; in a continuous industrial production process, hydrogen may be optionally introduced into the hydroformylation reaction according to the gas composition of the synthesis gas introduced, so as to adjust the molar ratio of hydrogen to carbon monoxide in the synthesis gas to be within the range of (0.3-5):1;

[0020] The hydroformylation reaction may be carried out using a reactor commonly used in the art. Preferably, the hydroformylation reaction may be carried out using at least one autoclave reactor. When multiple reactors are used, the reactors may be connected in series or in parallel.

[0021] The hydroformylation reaction can adopt the hydroformylation reaction conditions commonly used in the prior art. For example, the conditions of the hydroformylation reaction are: reaction temperature of 50 to 150° C., reaction pressure of 0.5 to 8 MPa, and reaction time of 30 to 180 min; preferably, the reaction temperature is 80 to 130° C., reaction pressure is 1 to 7 MPa, and reaction time is 30 to 120 min;

[0022] The proportion of the liquid phase returned to the hydroformylation reaction can be adjusted within a wide range. For example, the liquid phase product P1-1 returned to the hydroformylation reaction is 10 to 90%, preferably 10 to 50%, of the total amount of the liquid phase product P1 after the hydroformylation reaction. The temperature of the liquid phase product P1-1 after cooling is 20 to 100° C., preferably 40 to 100° C., and can be used as a coolant to control the temperature of the hydroformylation reaction.

[0023] The pressure reduction method of the liquid product P1-2 can be a commonly used pressure reduction method in the art, preferably a two-stage pressure reduction method, and the pressure of the liquid product P1-2 after pressure reduction is 0.5 to 2.5 MPa, preferably 0.5 to 2 MPa;

[0024] The separation operation after depressurization can adopt the separation operation process commonly used in the art. Preferably, the operation mode of separation of the liquid phase component P1-2 after depressurization is alternate depressurization and flash separation;

[0025] The first catalyst and the solvent S1 or a mixture thereof can be returned to the hydroformylation reaction in the form of a mixture comprising the first catalyst and the solvent, or the first catalyst and the solvent can be separated and then returned to the hydroformylation reaction separately. For example, an oxygen-containing gas (such as air) is introduced into the mixture comprising the first catalyst and the solvent, and the catalyst and the liquid phase are separated by centrifugation. The liquid phase is separated by separation or distillation and then circulated to the hydroformylation reaction as a solvent.

[0026] According to a specific embodiment of the present invention, in step (2):

[0027] The second catalyst C2 comprises a carrier and a supported metal active component. Preferably, the carrier is selected from at least one of alumina and carbon powder, and the metal active component is a component containing at least one of platinum, palladium, ruthenium, rhodium, lanthanum, rhenium and nickel.

[0028] The molar ratio of acetoxypropionaldehyde to hydrogen is 1:(1-20), preferably 1:(1-10), based on the acetoxypropionaldehyde in the crude acetoxypropionaldehyde;

[0029] In the hydrogenation reaction, the mass ratio of water to acetoxypropionaldehyde in the crude acetoxypropionaldehyde is 1:(1-5), preferably 1:(1-2);

[0030] The hydrogenation reaction can adopt the hydrogenation reactor equipment commonly used in the art. For example, the reactor of the hydrogenation reaction is a fixed bed reactor or a tank reactor. The reactor of the hydrogenation reaction can be one reactor or multiple reactors connected in series, parallel or in combination. When the reactor of the hydrogenation reaction is a fixed bed reactor, the second catalyst C2 is a catalyst with γ-alumina as a carrier and loaded with an active component containing at least one metal selected from platinum, palladium, ruthenium, rhodium, lanthanum, rhenium and nickel. The material space velocity of the fixed bed reactor is 0.05-15h -1 , preferably 0.05~10h -1 ; When the reactor for the hydrogenation reaction is a kettle reactor, the second catalyst C2 is a catalyst with γ-alumina or carbon powder as a carrier and loaded with an active component containing at least one metal of platinum, palladium, ruthenium, rhodium and nickel, or a Raney nickel catalyst composed of fine nickel-aluminum alloy grains with a porous structure; and / or, the molar amount of the second catalyst C2 is 0.5 to 10% of the molar amount of acetoxypropionaldehyde in the crude acetoxypropionaldehyde, and the acetoxypropionaldehyde includes 2-acetoxypropionaldehyde and 3-acetoxypropionaldehyde.

[0031] The hydrogenation reaction can adopt the hydrogenation reaction conditions disclosed in the art. For example, the conditions of the hydrogenation reaction are: reaction temperature of 60-110° C., reaction pressure of 2-10 MPa, and reaction time of 30-180 min; preferably, the conditions of the hydrogenation reaction are: reaction temperature of 60-100° C., reaction pressure of 2-8 MPa, and reaction time of 30-120 min.

[0032] According to a specific embodiment of the present invention, in step (3):

[0033] The third catalyst is selected from at least one of an acidic cation exchange resin and a chelated ion exchange resin, wherein the acidic cation exchange resin and the chelated ion exchange resin are not particularly limited, and can be an acidic cation exchange resin and a chelated ion exchange resin commonly used in the prior art, for example, a strongly acidic styrene cation exchange resin;

[0034] The solvent in the third catalyst solution C3 is a mixed solvent of water and an organic solvent; preferably, in the third catalyst solution C3, the organic solvent is selected from at least one of benzene and toluene; water accounts for 10 to 90 wt% of the total weight of the solvent; more preferably, in the third catalyst solution C3, the organic solvent is toluene, and water accounts for 30 to 70 wt% of the total weight of the solvent;

[0035] The mass ratio of the liquid phase product containing acetoxypropanol to the solvent in the third catalyst solution C3 is 1:(0.5-50), preferably 1:(0.5-30);

[0036] The amount of the third catalyst used can be the amount commonly used in the prior art, and can be adjusted within a wide range. For example, the mass ratio of acetoxypropanol in the liquid phase product to the third catalyst in the third catalyst solution C3 is 1:(0.005-0.2), preferably 1:(0.005-0.15);

[0037] The hydrolysis reaction may adopt the hydrolysis process conditions commonly used in the prior art, for example, the conditions of the hydrolysis reaction are: temperature of 50-120° C., pressure of 0-1 MPa, and reaction time of 5-120 min; preferably, the conditions of the hydrolysis reaction are: temperature of 50-100° C., pressure of 0.1-0.5 MPa, and reaction time of 5-30 min;

[0038] The separation method after the hydrolysis reaction can adopt the separation treatment process commonly used in the art, for example, the separation method is at least one of distillation separation, membrane separation, and phase separation, preferably phase separation.

[0039] According to a specific embodiment of the present invention, in step (4):

[0040] The separation treatment is distillation. The distillation method can adopt the distillation methods commonly used in the art, such as one or more combinations of atmospheric distillation, vacuum distillation, pressure swing distillation, azeotropic distillation, and extractive distillation. The distillation conditions can also adopt the distillation conditions commonly used in the art. Preferably, the operating conditions of the distillation are: pressure of 5 to 201 kPa, number of plates of 5 to 60, and reflux ratio of 0.1 to 20; more preferably, the operating conditions of the distillation are: pressure of 5 to 151 kPa, number of plates of 5 to 50, and reflux ratio of 0.1 to 10. Specifically, the hydrolysis reaction product is first separated in a primary separation tower, and a stream rich in water and acetic acid is obtained at the top of the tower, and a stream rich in propylene glycol is obtained at the bottom of the tower. After the propylene glycol-rich stream is sent to a propylene glycol tower for separation, a 1,2-propylene glycol product is obtained at the top of the tower, and a 1,3-propylene glycol product is obtained at the bottom of the tower; a stream rich in water and acetic acid is sent to an extractive distillation tower together with an extractant, and the water obtained at the top of the tower is circulated back to the hydrolysis reaction unit, the solvent-rich and acetic acid stream in the bottom of the tower is sent to an extractant recovery tower for further separation, the extractant obtained in the bottom of the tower is circulated back to the extractive distillation tower, and the acetic acid product is obtained at the top of the tower.

[0041] The second object of the present invention is to provide the above method for continuously preparing 1,2-propylene glycol and 1,3-propylene glycol, and its application in the preparation of 1,2-propylene glycol and 1,3-propylene glycol.

[0042] The method for preparing propylene glycol from vinyl acetate as a raw material of the present invention sequentially undergoes hydroformylation reaction, hydrogenation reaction, hydrolysis reaction and refining process, and can obtain high-purity 1,2-propylene glycol and 1,3-propylene glycol products, and produce acetic acid as a by-product. Water can be used as a solvent for the hydrolysis unit, separated from the refining unit, and returned to the hydrogenation unit for recycling as a solvent for the hydrogenation unit. While meeting the process requirements, water is recycled, the process is simplified, and the water treatment process is reduced. In the continuous preparation method provided by the present invention, the raw materials are safer, the process is simple, easy to operate, and the product composition is diverse, and the market adaptability is strong. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The present invention provides a process flow chart of the method for continuously preparing 1,2-propylene glycol and 1,3-propylene glycol.

[0044] Description of reference numerals:

[0045] 1-hydroformylation reaction unit; 2-gas-liquid separation unit; 3-hydrogenation reaction unit; 4-hydrolysis reaction unit; 5-refining unit; 6-synthesis gas; 7-vinyl acetate (including catalyst); 8-hydrogen; 9-third catalyst solution; 10-water; 11-non-condensable gas in the hydroformylation reaction product; 12-non-condensable gas in the hydrogenation reaction product; 13-circulation of the first catalyst solution and the solvent or a mixture thereof; 14-circulation of the hydroformylation reaction product P1-1; 15-1,2-propylene glycol; 16-1,3-propylene glycol; 17-acetic acid; 18-circulation of the third catalyst and the solvent or a mixture thereof; 19-water circulation. DETAILED DESCRIPTION

[0046] 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.

[0047] 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.

[0048] Example 1

[0049] The method provided in this embodiment is based on Figure 1 The process flow shown is carried out using the process operations in a continuous production process as a specific illustration.

[0050] Vinyl acetate 7, synthesis gas 6 and the first catalyst solution 13 (the solvent is 3-acetoxypropionaldehyde, and the amount of rhodium compound in the solution is 12.69% based on HRh(CO)3L) are fed into the hydroformylation reaction unit, wherein the introduction rate of vinyl acetate is 2829 kg / h, the introduction rate of the first catalyst solution is 783 kg / h, the feed molar ratio of synthesis gas to vinyl acetate in the reactor is maintained at about 1.90:1, the hydroformylation reaction temperature is 110°C, the reaction pressure is 6.0 MPa, the reaction time is 70 min, the proportion of the hydroformylation reaction product P1-1 recycled to the total extracted liquid phase is 0.23, and the reaction product P1-1 is cooled to 45°C and then circulated to the hydroformylation reaction unit.

[0051] The liquid phase P1-2 of the hydroformylation reaction product enters the gas-liquid separation unit 2, where it is reduced in pressure to 3.5 MPa and 1.0 MPa in turn through two-stage pressure reduction, and is separated by a separation tower with 23 plates, an operating pressure of 20 KPa, and a reflux ratio of 1. 3649.2 kg of crude acetoxypropionaldehyde product is produced from the top of the tower, and 870 kg of the first catalyst solution is separated from the bottom of the tower and recycled to the hydroformylation reaction unit 1, in which the catalyst content is 12.69%.

[0052] The crude acetoxypropionaldehyde product and hydrogen 8 are fed into the hydrogenation unit 3, and are contacted and reacted on the second catalyst Ni / γ-Al2O3 (nickel content 20% by mass) in the solvent formed by water 10 and water circulation 19. The reactor used for the hydrogenation reaction is a fixed bed reactor. The water supplementation rate is 530kg / h, the water circulation rate is 2000kg / h, the hydrogen rate is 75kg / h, the hydrogenation reaction temperature is 110°C, the reaction pressure is 6.5Mpa, and the reaction space velocity is 2h -1 , the hydrogenation product obtained is sent to the hydrolysis reaction unit 4.

[0053] The mixture of the hydrogenated product, the third catalyst and the solvent is circulated 18 and sent to the hydrolysis reaction unit for hydrolysis reaction. The circulation rate of the third catalyst solution is 2000kg / h, and it contains 400kg of the third catalyst strong acid styrene cation exchange resin. The hydrolysis reaction temperature is 80°C, the reaction pressure is 0.3MPa, and the reaction time is 15min. After the hydrolysis product is phase separated, the organic phase (containing the third catalyst) 18 is circulated back to the hydrolysis reaction unit, and the aqueous phase (containing the hydrolysis reaction product) 19 is sent to the refining unit 5.

[0054] The aqueous phase containing the hydrolysis reaction product obtained by the hydrolysis reaction unit 4 is sent to the refining unit 5 for separation. First, it is separated by the primary separation tower, with an operating pressure of 50kPa, a plate number of 20, and a reflux ratio of 2. A stream rich in water and acetic acid is obtained at the top of the tower, and a stream rich in propylene glycol is obtained in the bottom of the tower. The propylene glycol-rich stream is sent to the propylene glycol tower for separation, with an operating pressure of 50kPa, a plate number of 30, and a reflux ratio of 7. The 1,2-propylene glycol product is obtained at the top of the tower, and the 1,3-propylene glycol product is obtained in the bottom of the tower. The stream rich in water and acetic acid is sent to the extractive distillation tower together with the circulating extractant ε-caprolactam, with an operating pressure of 0.1MPa, a plate number of 40, a reflux ratio of 3, and water 19 is obtained at the top of the tower and circulated back to the hydrolysis reaction unit. The rich solvent and acetic acid stream in the bottom of the tower are sent to the extractant recovery tower, with an operating pressure of 50kPa, a plate number of 8, and a reflux ratio of 2.1. The extractant obtained in the bottom of the tower is circulated back to the extractive distillation tower, and the acetic acid product is obtained at the top of the tower. The refining unit produces 1120kg / h of 1,2-propylene glycol, 1085kg / h of 1,3-propylene glycol and 1742kg / h of acetic acid, with product quality purity exceeding 99.5%.

[0055] Example 2

[0056] The process of Example 1 was followed, except that:

[0057] Vinyl acetate 7, synthesis gas 6 and a first catalyst and solvent mixture 13 (the solvent is 3-acetoxypropionaldehyde, and the amount of rhodium compound in the solution is 14.29% based on HRh(CO)3L) are fed into a hydroformylation reaction unit, wherein the introduction rate of vinyl acetate is 2829 kg / h, the introduction rate of the first catalyst and solvent mixture is 720 kg / h, the feed molar ratio of synthesis gas to vinyl acetate in the reactor is maintained at approximately 1.93:1, the hydroformylation reaction temperature is 120°C, the reaction pressure is 6.5 MPa, and the proportion of the hydroformylation reaction product P1-1 circulation to the total produced liquid phase P1 is 0.20.

[0058] The liquid phase P1-2 of the hydroformylation reaction product enters the gas-liquid separation unit 2, where it is reduced in pressure to 3.5 MPa and 1.0 MPa in turn through two-stage pressure reduction, and is separated by a separation tower with 23 plates, an operating pressure of 20 KPa, and a reflux ratio of 1. 3649.3 kg of crude acetoxypropionaldehyde product is produced from the top of the tower, and 800 kg of the first catalyst solution is separated from the bottom of the tower and recycled to the hydroformylation reaction unit 1, in which the catalyst content is 14.29%.

[0059] The crude acetoxypropionaldehyde product and hydrogen 8 are fed to the hydrogenation unit 3, and are contacted and reacted on the second catalyst in the solvent formed by water 10 and water circulation 19. The reactor used for the hydrogenation reaction is a fixed bed reactor. The water supplement amount is 530 kg / h, the water circulation amount is 2000 kg / h, the hydrogen amount is 75 kg / h, the hydrogenation reaction temperature is 100°C, the reaction pressure is 5.5 MPa, the reaction time is 70 min, and the hydrogenation product is fed to the hydrolysis reaction unit 4.

[0060] The mixture of the hydrogenation product, the third catalyst and the solvent is circulated 18 and sent to the hydrolysis reaction unit for hydrolysis reaction. The circulation amount of the mixture of the third catalyst and the solvent is 4000kg / h, and the catalyst content is 600kg. The hydrolysis reaction temperature is 70°C and the reaction pressure is 0.2MPa. After the hydrolysis product is phase separated, an organic phase containing the third catalyst and an aqueous phase containing the hydrolysis reaction product are obtained. Among them, the organic phase (containing the third catalyst) 18 is circulated back to the hydrolysis reaction unit, and the aqueous phase (containing the hydrolysis reaction product) 19 is sent to the refining unit 5.

[0061] The water phase (containing the hydrolysis reaction product) 19 obtained by the hydrolysis reaction unit 4 is sent to the refining unit 5 for separation. First, it is separated by the primary separation tower, with an operating pressure of 50kPa, a plate number of 20, and a reflux ratio of 2. A stream rich in water and acetic acid is obtained at the top of the tower, and a stream rich in propylene glycol is obtained in the bottom of the tower. The propylene glycol-rich stream is sent to the propylene glycol tower for separation, with an operating pressure of 50kPa, a plate number of 30, and a reflux ratio of 7. The 1,2-propylene glycol product is obtained at the top of the tower, and the 1,3-propylene glycol product is obtained in the bottom of the tower. The stream rich in water and acetic acid is sent to the extractive distillation tower together with the circulating extractant, with an operating pressure of 0.1MPa, a plate number of 40, a reflux ratio of 3, and the water 19 obtained at the top of the tower is circulated back to the hydrolysis reaction unit. The rich solvent and acetic acid stream in the bottom of the tower are sent to the extractant recovery tower, with an operating pressure of 50kPa, a plate number of 8, and a reflux ratio of 2.1. The extractant obtained in the bottom of the tower is circulated back to the extractive distillation tower, and the acetic acid product is obtained at the top of the tower. The refining unit produces 1120kg / h of 1,2-propylene glycol, 1083kg / h of 1,3-propylene glycol and 1748kg / h of acetic acid, with product purity exceeding 99.5%.

[0062] Example 3

[0063] The process of Example 1 was followed, except that:

[0064] Vinyl acetate 7, synthesis gas 6 and a first catalyst and solvent mixture 13 (the solvent is 3-acetoxypropionaldehyde, and the amount of cobalt compounds in the solution is 10.08% in terms of cobalt octacarbonyl) are fed into a hydroformylation reaction unit, wherein the introduction rate of vinyl acetate is 3100 kg / h, the introduction rate of the first catalyst and solvent mixture is 720 kg / h, the feed molar ratio of synthesis gas to vinyl acetate in the reactor is maintained at about 1.86:1, the hydroformylation reaction temperature is 107°C, the reaction pressure is 6.5 MPa, and the proportion of the hydroformylation reaction product P1-1 recycled after cooling to the total produced liquid phase P1 is 0.45.

[0065] The liquid phase P1-2 of the hydroformylation reaction product enters the gas-liquid separation unit 2, and is successively reduced to 3.5MPa and 1.0MPa by two-stage pressure reduction in the gas-liquid separation unit 2. 150kg / h of air is introduced into the liquid phase after pressure reduction, and the catalyst and liquid phase are separated by centrifugation. The liquid phase is separated into a crude product of 4000.4kg / h by a separation tower, the separation tower has 23 plates, an operating pressure of 30Kpa, a reflux ratio of 1, and 719.3kg / h is produced from the bottom of the tower as a solvent cycle. The produced solvent is partially or completely returned to the first reaction unit 1 and the second reaction unit 2 as needed, which are 647kg / h and 72kg / h respectively, and the remaining part is discharged for recovery. The separated catalyst is partially or completely returned to the first reaction unit 1 and the second reaction unit 2 as needed, which are 72.56kg / h and 8.06kg / h respectively, and the remaining part is discharged for recovery.

[0066] The crude acetoxypropionaldehyde product and hydrogen 8 are sent to the hydrogenation unit 3, and are contacted and reacted on the second catalyst in the solvent formed by water 10 and water circulation 19. The reactor used for the hydrogenation reaction is a fixed bed reactor. The water supplement amount is 530 kg / h, the water circulation amount is 2000 kg / h, the hydrogen amount is 75 kg / h, the hydrogenation reaction temperature is 102°C, the reaction pressure is 5.5 MPa, the reaction time is 80 min, and the hydrogenation product is obtained and sent to the hydrolysis reaction unit 4.

[0067] The mixture of the hydrogenation product, the third catalyst and the solvent is circulated 18 and sent to the hydrolysis reaction unit for hydrolysis reaction. The circulation amount of the mixture of the third catalyst and the solvent is 4000kg / h, containing 650kg of the third catalyst, the hydrolysis reaction temperature is 65°C, and the reaction pressure is 0.2MPa. After the hydrolysis product is phase separated, an organic phase containing the third catalyst and an aqueous phase containing the hydrolysis reaction product are obtained, wherein the organic phase (containing the third catalyst) 18 is circulated back to the hydrolysis reaction unit, and the aqueous phase (containing the hydrolysis reaction product) 19 is sent to the refining unit 5.

[0068] The water phase (containing the hydrolysis reaction product) 19 obtained by the hydrolysis reaction unit 4 is sent to the refining unit 5 for separation. First, it is separated by the primary separation tower, with an operating pressure of 50kPa, a plate number of 20, and a reflux ratio of 2. A stream rich in water and acetic acid is obtained at the top of the tower, and a stream rich in propylene glycol is obtained in the bottom of the tower. The propylene glycol-rich stream is sent to the propylene glycol tower for separation, with an operating pressure of 50kPa, a plate number of 30, and a reflux ratio of 7. The 1,2-propylene glycol product is obtained at the top of the tower, and the 1,3-propylene glycol product is obtained in the bottom of the tower. The stream rich in water and acetic acid is sent to the extractive distillation tower together with the circulating extractant, with an operating pressure of 0.1MPa, a plate number of 40, a reflux ratio of 3, and the water 19 obtained at the top of the tower is circulated back to the hydrolysis reaction unit. The rich solvent and acetic acid stream in the bottom of the tower are sent to the extractant recovery tower, with an operating pressure of 50kPa, a plate number of 8, and a reflux ratio of 2.1. The extractant obtained in the bottom of the tower is circulated back to the extractive distillation tower, and the acetic acid product is obtained at the top of the tower. The refining unit produces 1230kg / h of 1,2-propylene glycol, 1190kg / h of 1,3-propylene glycol and 1911kg / h of acetic acid, with product purity exceeding 99.5%.

[0069] 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 continuously preparing 1,2-propylene glycol and 1,3-propylene glycol, comprising: Vinyl acetate and synthesis gas are subjected to a hydroformylation reaction under the action of a catalyst, and then subjected to a hydrogenation reaction and a hydrolysis reaction. The products obtained after the hydrolysis are refined to obtain 1,2-propylene glycol and 1,3-propylene glycol; wherein the solvent used in the hydroformylation reaction is an acyloxypropionaldehyde compound, and the solvent used in the hydrogenation reaction is water.

2. The method according to claim 1, characterized in that: After the hydroformylation reaction, part of the hydroformylation liquid product is cooled and then returned to the hydroformylation reaction; and / or, The water obtained by separating the products after the hydrolysis reaction is returned to the hydrogenation reaction.

3. The method according to claim 1 or 2, characterized in that: The method specifically comprises the following steps: (1) vinyl acetate and synthesis gas are contacted with a first catalyst solution C1 to carry out a hydroformylation reaction, a gaseous component obtained by the hydroformylation reaction is discharged, and a liquid component P1 obtained by the hydroformylation reaction is divided into two parts, one part of the liquid component P1-1 is cooled and returned to the hydroformylation reaction, and the remaining liquid component P1-2 is separated by reducing pressure to obtain a first catalyst and solvent S1 or a mixture thereof, and crude acetoxypropionaldehyde, wherein the first catalyst and solvent S1 or a mixture thereof are returned to the hydroformylation reaction; (2) subjecting the crude acetoxypropanal, hydrogen and water to a hydrogenation reaction under the action of a second catalyst C2, discharging a gaseous component obtained after the hydrogenation reaction, and obtaining a liquid product containing acetoxypropanol; (3) contacting the liquid product containing acetoxypropanol with the third catalyst solution C3 to carry out a hydrolysis reaction, and obtaining the third catalyst and solvent S2 or a mixture thereof, and a hydrolysis reaction product after separation, wherein the third catalyst and solvent S2 or a mixture thereof are recycled to the hydrolysis reaction; (4) separating and treating the hydrolysis reaction product obtained in step (3) to obtain water, 1,2-propylene glycol, 1,3-propylene glycol and acetic acid, wherein the separated water is recycled to the hydrogenation reaction.

4. The method according to claim 3, characterized in that In the step (1): The first catalyst is selected from at least one compound containing metal rhodium and / or cobalt, preferably at least one of octacarbonyl cobalt and L-coordinated tricarbonyl rhodium hydride; and / or, The solvent S1 in the first catalyst solution C1 is an acyloxypropionaldehyde compound, preferably acetoxypropionaldehyde; and / or, The content of the first catalyst in the first catalyst solution C1 is 1 to 23 wt%, preferably 10 to 23 wt%; and / or, The molar ratio of vinyl acetate to the first catalyst solution C1 is (1-10):1, preferably (1-8):1, wherein the first catalyst solution C1 is calculated based on the total molar amount of the first catalyst and the solvent; and / or, The synthesis gas contains hydrogen and carbon monoxide, preferably, the molar ratio of hydrogen to carbon monoxide is (0.3-5):1; and / or, The molar ratio of vinyl acetate to synthesis gas is 1:(1-21), preferably 1:(1-10).

5. The method according to claim 3, characterized in that: In the step (1): Optionally, hydrogen is introduced into the hydroformylation reaction; and / or, The hydroformylation reaction uses at least one autoclave reactor; and / or, The conditions of the hydroformylation reaction are: a reaction temperature of 50 to 150° C., and / or a reaction pressure of 0.5 to 8 MPa; preferably, a reaction temperature of 80 to 130° C., and / or a reaction pressure of 1 to 7 MPa; and / or, The liquid product P1-1 returned to the hydroformylation reaction is 10 to 90%, preferably 10 to 50%, of the total amount of the liquid product P1 after the hydroformylation reaction; and / or The temperature of the liquid product P1-1 after cooling is 20 to 100° C., preferably 40 to 100° C.; and / or, The pressure of the liquid product P1-2 after decompression is 0.5 to 2.5 MPa, preferably 0.5 to 2 MPa.

6. The method according to claim 3, characterized in that In the step (2): The second catalyst C2 comprises a carrier and a supported metal active component. Preferably, the carrier is selected from at least one of alumina and carbon powder, and the metal active component is a component containing at least one of platinum, palladium, ruthenium, rhodium, lanthanum, rhenium and nickel; and / or, The molar ratio of acetoxypropionaldehyde to hydrogen is 1:(1-20), preferably 1:(1-10), based on the acetoxypropionaldehyde in the crude acetoxypropionaldehyde; and / or In the hydrogenation reaction, the mass ratio of water to acetoxypropionaldehyde in the crude acetoxypropionaldehyde is 1:(1-5), preferably 1:(1-2); and / or, The reactor for the hydrogenation reaction is a fixed bed reactor or a tank reactor; and / or, The conditions for the hydrogenation reaction are: a reaction temperature of 60 to 110° C., and / or a reaction pressure of 2 to 10 MPa; preferably, the conditions for the hydrogenation reaction are: a reaction temperature of 60 to 100° C., and / or a reaction pressure of 2 to 8 MPa.

7. The method according to claim 6, characterized in that When the reactor for the hydrogenation reaction is a fixed bed reactor, the second catalyst C2 is a catalyst with γ-alumina as a carrier and loaded with an active component containing at least one metal selected from platinum, palladium, ruthenium, rhodium, lanthanum, rhenium and nickel; and / or the material space velocity of the fixed bed reactor is 0.05 to 15 h -1 , preferably 0.05~10h -1 ;or, When the reactor for the hydrogenation reaction is a kettle reactor, the second catalyst C2 is a catalyst with γ-alumina or carbon powder as a carrier and loaded with an active component containing at least one metal of platinum, palladium, ruthenium, rhodium and nickel, or a Raney nickel catalyst composed of fine nickel-aluminum alloy grains with a porous structure; and / or, the molar amount of the second catalyst C2 is 0.5 to 10% of the molar amount of acetoxypropionaldehyde in the crude acetoxypropionaldehyde, preferably 0.5 to 5%.

8. The method according to claim 3, characterized in that In the step (3): The third catalyst is selected from at least one of an acidic cation exchange resin and a chelated ion exchange resin; and / or, The solvent in the third catalyst solution C3 is a mixed solvent of water and an organic solvent; preferably, in the third catalyst solution C3, the organic solvent is selected from at least one of benzene and toluene; and / or, water accounts for 10 to 90 wt% of the total weight of the solvent; more preferably, in the third catalyst solution C3, the organic solvent is toluene, and / or, water accounts for 30 to 70 wt% of the total weight of the solvent; and / or, The mass ratio of the liquid phase product containing acetoxypropanol to the solvent in the third catalyst solution C3 is 1:(0.5-50), preferably 1:(0.5-30); and / or, The mass ratio of acetoxypropanol in the liquid phase product to the third catalyst in the third catalyst solution C3 is 1:(0.005-0.2), preferably 1:(0.005-0.15); and / or, The conditions of the hydrolysis reaction are: a temperature of 50 to 120° C., and / or a pressure of 0 to 1 MPa; preferably, the conditions of the hydrolysis reaction are: a temperature of 50 to 100° C., and / or a pressure of 0.1 to 0.5 MPa; and / or, The separation method is at least one of distillation separation, membrane separation, and phase separation, preferably phase separation.

9. The method according to claim 3, characterized in that: In the step (4): The separation treatment is distillation. Preferably, the operating conditions of the distillation are: pressure of 5 to 201 kPa, and / or, the number of plates is 5 to 60, and / or, the reflux ratio is 0.1 to 20; more preferably, the operating conditions of the distillation are: pressure of 5 to 151 kPa, and / or, the number of plates is 5 to 50, and / or, the reflux ratio is 0.1 to 10.

10. A method for continuously preparing 1,2-propylene glycol and 1,3-propylene glycol according to any one of claims 1 to 9, and use thereof in the preparation of 1,2-propylene glycol and 1,3-propylene glycol.

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