Method for preparing 1, 3-propylene glycol based on copper complex catalysis

Abstract

The invention discloses a method for preparing 1, 3-propylene glycol based on catalysis of a copper complex, and relates to the technical field of catalytic hydrogenation of aldehyde. According to the method, the problems of high reaction temperature and poor selectivity in the prior art are solved, the reaction process is simple, the yield of 1, 3-propylene glycol is high, and the selectivity is good; a cheap copper catalyst phosphine ligand is used, so that the cost is relatively low; the reaction conditions are mild, the temperature and the pressure are relatively low, and the requirement on production equipment is not high; the reaction system is wide in application range; the 1, 3-propylene glycol is prepared by hydrogenation of the 3-hydroxypropionaldehyde, the method is milder and quicker, and the method is also suitable for hydrogenation reaction of other aldehyde substances.

Description

Technical Field

[0001] This invention relates to the technical field of catalytic hydrogenation of aldehydes, specifically a method for preparing 1,3-propanediol based on copper complex catalysis. Background Technology

[0002] 1,3-Propanediol is an important chemical raw material, mainly used as a plasticizer, detergent, and preservative, and also in the food, cosmetics, and pharmaceutical industries. 1,3-Propanediol is equally important in polymer materials; its polycondensation with terephthalic acid yields polypropylene terephthalate (PTT), which exhibits superior properties compared to the corresponding polyethylene terephthalate (PET) or polybutylene terephthalate (PBT).

[0003] The preparation methods of 1,3-propanediol are broadly classified into two categories: chemical methods and biological methods. Chemical methods include ethylene oxide hydroformylation-hydrogenation, one-step ethylene oxide process, acrolein hydration-hydrogenation, and vinyl acetate hydroformylation, while biological methods include microbial fermentation using glycerol, glucose, and cellulose as raw materials. The ethylene oxide hydroformylation-hydrogenation method was first used by Shell in the 1990s. A patent filed around the same time used a phosphine-ligand-complexed cobalt carbonyl as a catalyst, with calcium acetate as an auxiliary agent, to synthesize 3-hydroxypropane from ethylene oxide and syngas (US5210318, US5304691), followed by hydrogenation using a nickel-based catalyst to obtain 1,3-propanediol. However, the hydroformylation and hydrogenation process of ethylene oxide is technically challenging and requires significant equipment investment. Furthermore, the reaction pressure exceeds 15 MPa, placing higher demands on reactor design and structure. The one-step ethylene oxide process uses ethylene oxide as a raw material, undergoing hydroformylation and hydrogenation reactions with syngas under the action of a hydroformylation catalyst to directly generate 1,3-propanediol. This simplifies the reaction steps and avoids the possibility of byproducts generated during the separation and hydrogenation of the intermediate product 3-hydroxypropanal. However, the selectivity of 1,3-propanediol is low. In the acrolein hydration-hydrogenation process, acrolein is first hydrated to obtain 3-hydroxypropanal, followed by hydrogenation to obtain 1,3-propanediol. However, this process has poor conversion rate and selectivity. Using ion exchange resins to promote the reaction significantly improves the product yield, but the resins are expensive, have poor stability, and are prone to deactivation.

[0004] Besides chemical methods, with the development of green chemistry and biotechnology, the preparation of 1,3-propanediol by bio-fermentation has also been a field of great interest in the past decade. In this field, DuPont successfully prepared 1,3-propanediol using glucose as a raw material and genetically engineered bacteria as fermentation microorganisms. The advantages of bio-fermentation are low investment and mild conditions, but it is difficult to achieve large-scale operation. Although the fermentation steps are simple, separation and purification are challenging, especially for textile fibers which require high product purity, increasing costs. Therefore, this invention proposes a method for preparing 1,3-propanediol based on copper complex catalysis to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing 1,3-propanediol based on copper complex catalysis, so as to solve the problems mentioned in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: adding 3-hydroxypropanal, copper catalyst, phosphine ligand, inorganic base salt, and solvent to a reaction vessel, reacting, purifying, and distilling under reduced pressure to obtain 1,3-propanediol.

[0007] Furthermore, the 3-hydroxypropionaldehyde is obtained by reacting acrolein, hydroquinone, and water under the action of a silica-alumina solid acid catalyst, followed by purification and vacuum distillation.

[0008] Furthermore, the process conditions for the reaction are as follows: under a hydrogen atmosphere, the pressure is 0.1~4MPa, preferably 0.1~2MPa; the temperature is 15~80℃, preferably 30~50℃; and the time is 4~18h, preferably 8~14h.

[0009] Furthermore, the molar ratio of 3-hydroxypropionaldehyde to copper catalyst is 1:(0.005~0.2), preferably 1:(0.005~0.02).

[0010] Furthermore, the phosphine ligand is any one of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine), tris(3,5-xylyl)phosphine, 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, and 1,2-bis(diphenylphosphine)ethane.

[0011] Furthermore, the molar ratio of 3-hydroxypropionaldehyde to phosphine ligand is 1:(0.005~0.2), preferably 1:(0.005~0.02).

[0012] Furthermore, the inorganic alkali salt is either sodium carbonate or potassium carbonate.

[0013] Furthermore, the molar ratio of 3-hydroxypropionaldehyde to the inorganic base salt is 1:(0.01~0.5), preferably 1:(0.01~0.2).

[0014] Furthermore, the copper catalyst is either copper chloride or copper acetate.

[0015] Furthermore, the solvent is at least one selected from methanol, diethyl ether, ethyl acetate, ethanol, and isopropanol.

[0016] In the above technical solution, the present invention overcomes the problems of high reaction temperature and poor selectivity in the prior art. The reaction process of the present invention is simple and does not require high production equipment. The reaction system has a wide range of applications. The method of preparing 1,3-propanediol by hydrogenation of 3-hydroxypropanal is milder and faster. In addition, the method is also applicable to the hydrogenation reaction of other aldehydes, such as cyclohexaneformin and cinnamaldehyde.

[0017] Furthermore, the phosphine ligand can also be prepared by the following process: Step 1: Mix o-diphenylphosphine benzaldehyde with anhydrous sodium sulfate, add dichloromethane, stir, add 1,2-cyclohexanediamine dropwise, react at 40~50℃ for 4~6h, centrifuge, dry to obtain intermediate; Step 2: Add anhydrous ethanol and reducing agent to the intermediate, and reflux at 50-60°C for 8-10 hours under a nitrogen atmosphere. Adjust the pH to 7.5-8.5, centrifuge, and dry to obtain the phosphine ligand.

[0018] In the above technical solution, the present invention utilizes the addition reaction between the aldehyde group in o-diphenylphosphine benzaldehyde and the amino group in 1,2-cyclohexanediamine to obtain a diimine bisphosphine intermediate. Then, a reducing agent is used to reduce the carbon-nitrogen double bond to a carbon-nitrogen single bond to generate a more stable diamine bisphosphine ligand. Copper is used as the active metal, and nitrogen atoms are introduced. Compared with conventional phosphine ligands, the diamine bisphosphine ligand prepared by the present invention can stabilize the metal active center, improve the selectivity of the reaction, and form a more stable catalytic system by complexing with copper, thus ensuring the stability and reliability of the catalytic reaction and making the reaction conditions more mild.

[0019] Furthermore, the mass ratio of o-diphenylphosphine benzaldehyde, sodium sulfate, and 1,2-cyclohexanediamine is (1.5~2):3.5:(0.3~0.5).

[0020] Furthermore, the mass ratio of o-diphenylphosphine benzaldehyde to dichloromethane is 1:(8~10).

[0021] Furthermore, the mass ratio of reducing agent to intermediate is 1:(10~15).

[0022] Furthermore, the mass ratio of anhydrous ethanol to reducing agent is (40~50):1.5.

[0023] Furthermore, the reducing agent is any one of sodium borohydride, lithium aluminum hydride, or sodium triacetoxyborohydride.

[0024] Compared with the prior art, the beneficial effects of the present invention are: 1. The preparation process of this invention is simple, with high yield and good selectivity of 1,3-propanediol; it uses inexpensive copper catalyst and phosphine ligand as catalytic system, resulting in low cost; the reaction conditions are mild, with low temperature and pressure, and low requirements for production equipment; the reaction system has a wide range of applications; it uses 3-hydroxypropanal as the reaction raw material, resulting in high production efficiency, and the method is also applicable to the hydrogenation reaction of other aldehydes.

[0025] 2. This invention involves an addition reaction between the aldehyde group in o-diphenylphosphine benzaldehyde and the amino group in 1,2-cyclohexanediamine to obtain a diimine bisphosphine intermediate. A reducing agent is then used to reduce the carbon-nitrogen double bond to a carbon-nitrogen single bond, generating a more stable diamine bisphosphine ligand. Using copper as the active metal and introducing a nitrogen atom, compared to conventional phosphine ligands, the diamine bisphosphine ligand prepared by this invention can stabilize the metal active center, improve reaction selectivity, and form a more stable catalytic system by complexing with copper, ensuring the stability and reliability of the catalytic reaction, while also providing milder reaction conditions. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the following specific implementation: 3-Hydroxypropionaldehyde, CAS: 2134-29-4; 1,1'-Binaphthyl-2,2'-bisdiphenylphosphine, CAS: 98327-87-8; 4,5-Bis(diphenylphosphine)-9,9-dimethyloxanthracene, CAS:161265-03-8; Tris(3,5-dimethyl)phosphine, CAS: 69227-47-0; 1,2-Bis(diphenylphosphine)ethane, CAS: 1663-45-2; o-Diphenylphosphine benzaldehyde, CAS: 50777-76-9; 1,2-Cyclohexanediamine, CAS: 694-83-7. Example 1:

[0028] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.31 g of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine), 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 2.73 g of 1,3-propanediol. Example 2:

[0029] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 2.96 g of 1,3-propanediol. Example 3:

[0030] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.17 g of tris(3,5-xylyl)phosphine, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 2.98 g of 1,3-propanediol. Example 4:

[0031] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.2 g of 1,2-bis(diphenylphosphine)ethane, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 3.25 g of 1,3-propanediol. Example 5:

[0032] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.1 g of copper acetate, 0.2 g of 1,2-bis(diphenylphosphine)ethane, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 3.62 g of 1,3-propanediol. Example 6:

[0033] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.1 g of copper acetate, 0.2 g of 1,2-bis(diphenylphosphine)ethane, 0.26 g of sodium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 3.42 g of 1,3-propanediol. Example 7:

[0034] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.1 g of copper acetate, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 3.74 g of 1,3-propanediol. Example 8:

[0035] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.1 g of copper acetate, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 3.76 g of 1,3-propanediol. Example 9:

[0036] A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.1 g of copper acetate, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 50 °C for 6 h. After reaction, purification and vacuum distillation are performed to obtain 3.62 g of 1,3-propanediol.

[0037] Example 10: A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 3.70 g of 3-hydroxypropanal, 0.1 g of copper acetate, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 50 °C for 10 h. After reaction, purification and vacuum distillation are performed to obtain 3.76 g of 1,3-propanediol.

[0038] Example 11: A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 7.40 g of 3-hydroxypropanal, 0.2 g of copper acetate, 0.58 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.68 g of potassium carbonate, and 20 mL of isopropanol are added to a 100 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 50 °C for 10 h. After reaction, purification and vacuum distillation yield 7.56 g of 1,3-propanediol.

[0039] Example 12: A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 14.8 g of 3-hydroxypropanal, 0.2 g of copper acetate, 0.58 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.68 g of potassium carbonate, and 20 mL of isopropanol are added to a 100 mL autoclave. After the autoclave is assembled, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 50 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 14.96 g of 1,3-propanediol.

[0040] Example 13: A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 74 g of 3-hydroxypropanal, 2 g of copper acetate, 5.8 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 6.8 g of potassium carbonate, and 200 mL of isopropanol are added to a 500 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 50 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 74.7 g of 1,3-propanediol.

[0041] Example 14: A method for preparing 1,3-propanediol based on copper complex catalysis includes the following steps: 148 g of 3-hydroxypropanal, 2 g of copper acetate, 5.8 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 6.8 g of potassium carbonate, and 200 mL of isopropanol are added to a 500 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 2.0 MPa and a temperature of 50 °C for 16 h. After reaction, purification and vacuum distillation are performed to obtain 150.3 g of 1,3-propanediol.

[0042] Example 15: A method for preparing cyclohexylmethanol based on copper complex catalysis includes the following steps: 5.61 g of cyclohexylformaldehyde, 0.1 g of copper acetate, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 1.5 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 5.58 g of cyclohexylmethanol.

[0043] Example 16: A method for preparing cinnamyl alcohol based on copper complex catalysis includes the following steps: 6.61 g of cinnamaldehyde, 0.1 g of copper acetate, 0.29 g of 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, 0.34 g of potassium carbonate, and 10 mL of isopropanol are added to a 50 mL autoclave. After assembling the autoclave, nitrogen is purged three times, followed by hydrogen purging three times, and finally hydrogen is introduced. The reaction is carried out at a pressure of 0.8 MPa and a temperature of 40 °C for 12 h. After reaction, purification and vacuum distillation are performed to obtain 4.87 g of cinnamyl alcohol.

[0044] Example 17: This embodiment provides a method for preparing 1,3-propanediol based on copper complex catalysis, wherein the phosphine ligand is prepared by the following process: Step 1: Mix o-diphenylphosphine benzaldehyde with anhydrous sodium sulfate, add dichloromethane, stir, add 1,2-cyclohexanediamine dropwise, react at 40℃ for 4 hours, centrifuge, and dry to obtain the intermediate; the mass ratio of o-diphenylphosphine benzaldehyde, sodium sulfate, and 1,2-cyclohexanediamine is 1.5:3.5:0.3; the mass ratio of o-diphenylphosphine benzaldehyde to dichloromethane is 1:8; Step 2: Add anhydrous ethanol and sodium borohydride to the intermediate, reflux at 50°C for 8 hours under a nitrogen atmosphere, adjust the pH to 7.5, centrifuge, and dry to obtain the phosphine ligand; the mass ratio of reducing agent to intermediate is 1:10; the mass ratio of anhydrous ethanol to reducing agent is 40:1.5. 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.1 g of phosphine ligand, 0.34 g of potassium carbonate, and 10 mL of isopropanol were added to a 50 mL autoclave. After assembling the autoclave, nitrogen was purged three times, followed by hydrogen purging three times, and finally hydrogen was introduced. The reaction was carried out at a pressure of 1.1 MPa and a temperature of 30 °C for 12 h. After the reaction was completed, the product was purified and distilled under reduced pressure to obtain 3.77 g of 1,3-propanediol.

[0045] Example 18: This embodiment provides a method for preparing 1,3-propanediol based on copper complex catalysis, wherein the phosphine ligand is prepared by the following process: Step 1: Mix o-diphenylphosphine benzaldehyde with anhydrous sodium sulfate, add dichloromethane, stir, add 1,2-cyclohexanediamine dropwise, react at 45℃ for 5 hours, centrifuge, and dry to obtain the intermediate; the mass ratio of o-diphenylphosphine benzaldehyde, sodium sulfate, and 1,2-cyclohexanediamine is 1.5:3.5:0.4; the mass ratio of o-diphenylphosphine benzaldehyde to dichloromethane is 1:10. Step 2: Add anhydrous ethanol and sodium borohydride to the intermediate, reflux at 55°C for 9 hours under a nitrogen atmosphere, adjust the pH to 8.0, centrifuge, and dry to obtain the phosphine ligand; the mass ratio of reducing agent to intermediate is 1:12; the mass ratio of anhydrous ethanol to reducing agent is 45:1.5. 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.1 g of phosphine ligand, 0.34 g of potassium carbonate, and 10 mL of isopropanol were added to a 50 mL autoclave. After assembling the autoclave, nitrogen was purged three times, followed by hydrogen purging three times, and finally hydrogen was introduced. The reaction was carried out at a pressure of 1.3 MPa and a temperature of 40 °C for 12 h. After the reaction was completed, the product was purified and distilled under reduced pressure to obtain 3.78 g of 1,3-propanediol.

[0046] Example 19: This embodiment provides a method for preparing 1,3-propanediol based on copper complex catalysis, wherein the phosphine ligand is prepared by the following process: Step 1: Mix o-diphenylphosphine benzaldehyde with anhydrous sodium sulfate, add dichloromethane, stir, add 1,2-cyclohexanediamine dropwise, react at 50°C for 6 hours, centrifuge, and dry to obtain the intermediate; the mass ratio of o-diphenylphosphine benzaldehyde, sodium sulfate, and 1,2-cyclohexanediamine is 2:3.5:0.5; the mass ratio of o-diphenylphosphine benzaldehyde to dichloromethane is 1:10. Step 2: Add anhydrous ethanol and sodium borohydride to the intermediate, reflux at 50°C for 10 h under a nitrogen atmosphere, adjust the pH to 8.5, centrifuge, and dry to obtain the phosphine ligand; the mass ratio of reducing agent to intermediate is 1:15; the mass ratio of anhydrous ethanol to reducing agent is 50:1.5. 3.70 g of 3-hydroxypropanal, 0.07 g of copper chloride, 0.1 g of phosphine ligand, 0.34 g of potassium carbonate, and 10 mL of isopropanol were added to a 50 mL autoclave. After assembling the autoclave, nitrogen was purged three times, followed by hydrogen purging three times, and finally hydrogen was introduced. The reaction was carried out at a pressure of 1.2 MPa and a temperature of 40 °C for 12 h. After the reaction was completed, the product was purified and distilled under reduced pressure to obtain 3.75 g of 1,3-propanediol.

[0047] Comparative Example 1: This comparative example provides a method for the catalytic preparation of 1,3-propanediol, using copper oxide as a catalyst, with the remaining methods being the same as in Example 1.

[0048] Comparative Example 2: This comparative example provides a method for the catalytic preparation of 1,3-propanediol, using Raney nickel (model: Raney 6800) as a catalyst. The amount of Raney nickel added is 3.2% of the mass of 3-hydroxypropanal, and the rest of the method is the same as in Example 1.

[0049] experiment: Samples were prepared from the 1,3-propanediol obtained in Examples 1-14, 17-19 and Comparative Examples 1-2, and their properties were tested and the test results were recorded.

[0050] Purity test: The reaction products were analyzed using a gas chromatograph to test the purity and yield of 1,3-propanediol, and the data were recorded. Yield test: Weigh the actual mass of the reaction product and calculate the ratio to the theoretical mass, and record the yield.

[0051] Performance Comparison Table

[0052] Based on the data in the table above, the following conclusions can be clearly drawn: The 1,3-propanediol obtained in Examples 1-14 and 17-19 was compared with the 1,3-propanediol obtained in Comparative Examples 1-2. The detection results show that: A comparison of Examples 1-14 with Comparative Examples 1-2 shows that the method of preparing 1,3-propanediol in this invention has high purity and yield.

[0053] Examples 1-4 used different phosphine ligands, and the yield gradually increased from 72% to 86%, indicating that the ligand structure has a significant regulatory effect on catalytic activity. Among them, 1,2-bis(diphenylphosphine)ethane has a better effect, which can stabilize the copper active center and improve the reaction selectivity.

[0054] In Examples 5-14, the purity and yield of 1,3-propanediol were both 99.9% when copper acetate or copper chloride was combined with phosphine ligands, indicating that the method of the present invention has extremely high efficiency and selectivity under optimized conditions.

[0055] Examples 17-19 use bisamine bisphosphine ligands, which increase the yield and purity, further verifying the feasibility of the ligand synthesis process of the present invention. This ligand, by introducing nitrogen atoms, forms a more stable complex with copper, and the reaction pressure and temperature are lower, which improves the reliability and mildness of the catalytic system.

[0056] Examples 15-16 demonstrate that this method is applicable to the hydrogenation reaction of other aldehydes, with a yield of over 70%, proving that the catalytic system of this invention has broad applicability.

[0057] In summary, this invention, based on copper complex catalysis, effectively solves the problems of high reaction temperature and poor selectivity in the prior art by optimizing the catalyst, ligand, and reaction conditions. It achieves efficient and highly selective preparation of 1,3-propanediol, with low cost and mild conditions, and has significant industrial application value.

[0058] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing 1,3-propanediol based on copper complex catalysis, characterized in that: The process includes the following steps: adding 3-hydroxypropanal, a copper catalyst, a phosphine ligand, an inorganic base salt, and a solvent to a reaction vessel, reacting, purifying, and distilling under reduced pressure to obtain 1,3-propanediol.

2. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 1, characterized in that: The copper catalyst is either copper chloride or copper acetate; the phosphine ligand is any one of 1,1'-binaphthyl-2,2'-bis(diphenylphosphine), tris(3,5-xylyl)phosphine, 4,5-bis(diphenylphosphine)-9,9-dimethyloxanthracene, or 1,2-bis(diphenylphosphine)ethane; and the inorganic alkali salt is either sodium carbonate or potassium carbonate.

3. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 1, characterized in that: The molar ratio of 3-hydroxypropionaldehyde to copper catalyst is 1: (0.005~0.2).

4. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 1, characterized in that: The molar ratio of 3-hydroxypropionaldehyde to phosphine ligand is 1: (0.005~0.2).

5. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 1, characterized in that: The molar ratio of 3-hydroxypropanal to inorganic base salt is 1: (0.01~0.5).

6. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 1, characterized in that: The reaction process conditions are as follows: under a hydrogen atmosphere, pressure 0.1~4MPa, temperature 15~80℃, and time 4~18h.

7. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 2, characterized in that: The phosphine ligand can also be prepared by the following process: Step 1: Mix o-diphenylphosphine benzaldehyde with anhydrous sodium sulfate, add dichloromethane, stir, add 1,2-cyclohexanediamine dropwise, heat to react, centrifuge, and dry to obtain the intermediate; Step 2: Add anhydrous ethanol and reducing agent to the intermediate, reflux the reaction under a nitrogen atmosphere, adjust the pH to 7.5-8.5, centrifuge, and dry to obtain the phosphine ligand.

8. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 7, characterized in that: The mass ratio of o-diphenylphosphine benzaldehyde, sodium sulfate, and 1,2-cyclohexanediamine is (1.5~2):3.5:(0.3~0.5).

9. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 7, characterized in that: The mass ratio of reducing agent to intermediate is 1:(10~15).

10. The method for preparing 1,3-propanediol based on copper complex catalysis according to claim 7, characterized in that: The reducing agent is any one of sodium borohydride, lithium aluminum hydride, or sodium triacetoxyborohydride.

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