Method for purifying crude polycarbonate diol containing titanate catalyst

Abstract

The invention is suitable for the technical field of organic synthesis, and provides a method for purifying crude polycarbonate diol containing a titanate catalyst, which comprises the following steps: selecting dichloromethane, trichloromethane, tetrahydrofuran or ethyl acetate solvent, and dissolving the crude product according to the mass ratio of crude product PCDL to organic solvent to pure water of 1: (1-10): (1-10) under the condition of jacket hot water heating. Carrying out pressure filtration through high-purity nitrogen, separating filtrate from filter residues, standing and layering the filtrate, and respectively collecting an organic phase and a water phase; and secondly, transferring the organic phase to a concentration kettle, adjusting the temperature and the vacuum degree, recovering and recycling the organic solvent, and finally obtaining a qualified polycarbonate diol product. According to the method, the residual titanate catalyst in the polycarbonate diol product is effectively removed through an innovative purification process, and the production of the high-purity product is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and in particular relates to a method for purifying crude polycarbonate diol containing a titanate catalyst. Background Art

[0002] Polycarbonate diol (PCDL), a key polymer material, is widely used in the production of high-performance materials such as polycarbonate (PC). Its synthesis primarily involves two methods: a one-step process and a two-step process. In the one-step process, PCDL is synthesized by directly reacting a carbonate compound with a low-molecular-weight diol. In the two-step process, a low-molecular-weight PCDL is first prepared, and its molecular weight is subsequently increased through a polycondensation reaction to obtain the final product. Titanate catalysts are commonly used to catalyze these reactions, particularly in the preparation of PCDL from dimethyl carbonate and 1,6-hexanediol.

[0003] However, current technologies using titanate catalysts face a challenge: a small amount of catalyst residue remains in the resulting PCDL product. This unpurified PCDL can lead to further polycondensation in subsequent applications, especially during heating and melting, affecting the molecular weight and distribution of the PCDL and adversely impacting the performance of downstream products. Therefore, effectively removing residual catalyst from PCDL products is a pressing issue. Optimizing this process is crucial for improving PCDL product quality and expanding its applications. Summary of the Invention

[0004] The object of the present invention is to provide a method for purifying crude polycarbonate diol containing a titanate catalyst, aiming to solve the problems mentioned in the above background technology.

[0005] The present invention is achieved by a method for purifying a crude polycarbonate diol containing a titanate catalyst, comprising the following steps: Step 1: Select dichloromethane (DCM), chloroform, tetrahydrofuran (THF) or ethyl acetate as an organic solvent, and fully stir and dissolve the crude polycarbonate diol in a dissolution kettle at a mass ratio of crude polycarbonate diol: organic solvent: pure water = 1:1-10:1-10 under jacket hot water heating conditions; then, pass the mixed solution through a filter by pressurizing with high-purity nitrogen gas, collect the filtrate into a filtrate tank, and collect the filter residue into a dedicated storage tank; after the filtrate is allowed to stand and separate, the separated organic phase and aqueous phase enter their respective storage tanks; Step 2: The polycarbonate diol solution transferred from the organic phase storage tank enters a concentration kettle. By controlling the temperature and vacuum degree of the concentration kettle, the dichloromethane, chloroform, tetrahydrofuran or ethyl acetate organic solvent is condensed and recovered, and returned to the dissolution kettle for reuse. Finally, the qualified polycarbonate diol product remaining in the concentration kettle is stored in a polycarbonate diol product tank.

[0006] According to a further technical solution, in step 1, the jacket is heated to a temperature of 25-39°C with hot water.

[0007] A further technical solution is that in step one, the dissolving kettle is pressurized by high-purity nitrogen gas so that the pressure inside the dissolving kettle is maintained at 0.5 MPa.

[0008] According to a further technical solution, in step one, the filter residue mainly comprises titanium dioxide.

[0009] According to a further technical solution, in step 1, the separated water phase is returned to the polycarbonate diol dissolving kettle through a water phase reflux pump for recycling.

[0010] According to a further technical solution, in step 1, the organic solvent evaporated from the concentration kettle enters the crude product tank through the concentration kettle cooler, and then returns to the polycarbonate diol dissolution kettle through the organic phase reflux pump for recycling.

[0011] A further technical solution is that in step 2, the temperature of the concentration kettle is controlled to be 39-100° C. and the vacuum degree is controlled to be 3-30 KPa.

[0012] The present invention provides a method for purifying crude polycarbonate diol containing a titanate catalyst, which has the following beneficial effects: The present invention utilizes a titanate catalyst to catalyze the reaction of carbonate compounds with low-molecular-weight diols to prepare polycarbonate diols. Residual titanate catalysts in the product are effectively removed through an innovative purification process, resulting in high-purity polycarbonate diols. This process not only recycles solvents and water, reducing environmental pollution and resource waste, but also achieves efficient purification from laboratory to industrial scale by optimizing the amounts of organic solvents and pure water and adjusting reaction parameters. This significantly improves product quality and production efficiency, while also increasing the commercial value of byproducts. This process has broad application prospects and high industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a flow chart for purifying crude polycarbonate diol containing a titanate catalyst provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0015] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0016] like Figure 1 As shown, the process flow chart includes a polycarbonate diol crude product tank, a polycarbonate diol dissolving kettle, organic solvent storage tanks such as dichloromethane / chloroform / tetrahydrofuran / ethyl acetate, a pure water storage tank, a dissolving kettle filter, a filtrate tank, a titanium dioxide storage tank, an organic phase storage tank, an aqueous phase storage tank, a concentration kettle, a concentration kettle condenser, a vacuum pump unit, a dichloromethane / chloroform / tetrahydrofuran / ethyl acetate and other organic solvent crude product tanks, an organic phase reflux pump, an aqueous phase reflux pump, a PCDL product tank, etc.

[0017] Example 1

[0018] One embodiment of the present invention provides a method for purifying crude polycarbonate diol containing a titanate catalyst. The method uses a mass ratio of crude PCDL:DCM:pure water = 1:1:1. The catalyst is then removed by dissolution, pressure filtration, stratification, and concentration to obtain pure catalyst-free PCDL. The specific steps are as follows: 1) Crude product dissolution: Under heating conditions of jacket hot water (temperature 25°C), the materials are added into a dissolution kettle according to the mass ratio of crude PCDL:DCM:pure water = 1:1:1, and are fully stirred and dissolved to obtain a mixed solution containing titanium dioxide solid.

[0019] 2) Crude Product Filtration and Separation: High-purity nitrogen is introduced into the dissolution kettle to maintain the pressure at 0.5 MPa. The dissolution kettle discharge valve and the filter feed valve are opened to allow the mixed solution to pass through the filter. Titanium dioxide solids remain in the filter and are then collected in a titanium dioxide storage tank. The filtrate is stored in a filtrate tank. The filtrate in the filtrate tank is allowed to stand for 12 hours to obtain separate organic and aqueous phases.

[0020] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, use a pump to pump the material into the concentration kettle, and then turn on the vacuum unit to evacuate the vacuum kettle to maintain the pressure of the concentration kettle at 3 kPa; gradually heat the concentration kettle with low-pressure steam to evaporate the DCM in the material. The final temperature of the concentration kettle is maintained at 39°C. Continue the concentration reaction for 5 hours to obtain a high-purity PCDL product.

[0021] 4) Solvent Recovery: The aqueous phase in the filtrate tank enters the aqueous phase storage tank and is then pumped back to the dissolution kettle via the aqueous phase reflux pump, achieving aqueous phase recycling. The DMC solvent evaporated from the concentration kettle enters the crude DMC tank via the concentration kettle cooler and is then pumped back to the dissolution kettle via the organic phase reflux pump, achieving DMC solvent recycling.

[0022] Example 2

[0023] The difference from Example 1 is that: The mass ratio of crude PCDL:DCM:pure water is 1:10:10; the temperature of the jacket hot water heating is 39°C; the temperature of the concentration kettle is controlled at 100°C and the vacuum degree is 30KPa.

[0024] Example 3

[0025] The difference from Example 1 is that: The mass ratio of crude PCDL:DCM:pure water is 1:5:2; the temperature of the jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 80°C and the vacuum degree is 10KPa.

[0026] Example 4

[0027] One embodiment of the present invention provides a method for purifying crude polycarbonate diol containing a titanate catalyst. The method uses a mass ratio of crude PCDL:THF:pure water = 1:1:1. The catalyst is then removed by dissolution, pressure filtration, stratification, and concentration to obtain pure catalyst-free PCDL. The specific steps are as follows: 1) Crude product dissolution: Under heating conditions with jacketed hot water (temperature 25°C), the crude PCDL:THF:pure water = 1:1:1 mass ratio is added to a dissolution kettle and the mixture is stirred and dissolved to obtain a mixed solution containing titanium dioxide solid.

[0028] 2) Crude Product Filtration and Separation: High-purity nitrogen is introduced into the dissolution kettle to maintain the pressure at 0.5 MPa. The dissolution kettle discharge valve and the filter feed valve are opened to allow the mixed solution to pass through the filter. Titanium dioxide solids remain in the filter and are then collected in a titanium dioxide storage tank. The filtrate is stored in a filtrate tank. The filtrate in the filtrate tank is allowed to stand for 12 hours to obtain separate organic and aqueous phases.

[0029] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, use a pump to pump the material into the concentration kettle, and then turn on the vacuum unit to evacuate the vacuum kettle to maintain the pressure of the concentration kettle at 3 kPa; gradually heat the concentration kettle with low-pressure steam to evaporate the THF in the material. The final temperature of the concentration kettle is maintained at 39°C. Continue the concentration reaction for 5 hours to obtain a high-purity PCDL product.

[0030] 4) Solvent Recovery: The aqueous phase in the filtrate tank enters the aqueous phase storage tank and is then pumped back to the dissolution kettle via the aqueous phase reflux pump, achieving aqueous phase recycling. The THF solvent evaporated from the concentration kettle passes through the concentration kettle cooler and enters the crude THF tank. The organic phase reflux pump then pumps the THF back to the dissolution kettle, achieving THF solvent recycling.

[0031] Example 5

[0032] The difference from Example 4 is that: The mass ratio of crude PCDL:THF:pure water was 1:10:10; the temperature of the jacket hot water heating was 39° C.; the temperature of the concentration kettle was controlled at 100° C. and the vacuum degree was 30 KPa.

[0033] Example 6

[0034] The difference from Example 4 is that: The mass ratio of crude PCDL:THF:pure water is 1:7:2; the temperature of the jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 90°C and the vacuum degree is 10KPa.

[0035] Example 7

[0036] One embodiment of the present invention provides a method for purifying crude polycarbonate diol containing a titanate catalyst. The method uses a mass ratio of crude PCDL: ethyl acetate: pure water = 1:1:1. The catalyst is then removed by dissolution, pressure filtration, stratification, and concentration to obtain pure catalyst-free PCDL. The specific steps are as follows: 1) Crude product dissolution: Under jacket hot water (temperature 25°C), the crude PCDL: ethyl acetate: pure water = 1:1:1 mass ratio was added to a dissolution kettle and thoroughly stirred and dissolved to obtain a mixed solution containing titanium dioxide solid.

[0037] 2) Crude Product Filtration and Separation: High-purity nitrogen is introduced into the dissolution kettle to maintain the pressure at 0.5 MPa. The dissolution kettle discharge valve and the filter feed valve are opened to allow the mixed solution to pass through the filter. Titanium dioxide solids remain in the filter and are then collected in a titanium dioxide storage tank. The filtrate is stored in a filtrate tank. The filtrate in the filtrate tank is allowed to stand for 12 hours to obtain separate organic and aqueous phases.

[0038] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, use a pump to pump the material into the concentration kettle, and then turn on the vacuum unit to evacuate the vacuum kettle to maintain the pressure of the concentration kettle at 3 kPa; gradually heat the concentration kettle with low-pressure steam to evaporate the ethyl acetate in the material. The final temperature of the concentration kettle is maintained at 39°C. Continue the concentration reaction for 5 hours to obtain a high-purity PCDL product.

[0039] 4) Solvent Recovery: The aqueous phase in the filtrate tank enters the aqueous phase storage tank and is then pumped back to the dissolution kettle via the aqueous phase reflux pump, achieving aqueous phase recycling. The ethyl acetate solvent evaporated from the concentration kettle enters the crude ethyl acetate tank via the concentration kettle cooler and is then pumped back to the dissolution kettle via the organic phase reflux pump, achieving solvent ethyl acetate recycling.

[0040] Example 8

[0041] The difference from Example 7 is that: The mass ratio of crude PCDL: ethyl acetate: pure water is 1:10:10; the temperature of the jacket hot water heating is 39°C; the temperature of the concentration kettle is controlled at 100°C and the vacuum degree is 30KPa.

[0042] Example 9

[0043] The difference from Example 7 is that: The mass ratio of crude PCDL: ethyl acetate: pure water is 1:9:2; the temperature of the jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 80°C and the vacuum degree is 10KPa.

[0044] Example 10

[0045] One embodiment of the present invention provides a method for purifying crude polycarbonate diol containing a titanate catalyst. The method uses a mass ratio of crude PCDL: chloroform: pure water = 1:1:1. The catalyst is then removed by dissolution, pressure filtration, stratification, and concentration to obtain pure catalyst-free PCDL. The specific steps are as follows: 1) Crude product dissolution: Under heating conditions with jacketed hot water (temperature 25°C), the crude PCDL: chloroform: pure water = 1:1:1 mass ratio is added to a dissolution kettle and the mixture is stirred and dissolved to obtain a mixed solution containing titanium dioxide solid.

[0046] 2) Crude Product Filtration and Separation: High-purity nitrogen is introduced into the dissolution kettle to maintain the pressure at 0.5 MPa. The dissolution kettle discharge valve and the filter feed valve are opened to allow the mixed solution to pass through the filter. Titanium dioxide solids remain in the filter and are then collected in a titanium dioxide storage tank. The filtrate is stored in a filtrate tank. The filtrate in the filtrate tank is allowed to stand for 12 hours to obtain separate organic and aqueous phases.

[0047] 3) Concentration and purification: Open the organic phase discharge valve of the filtrate tank and the feed valve of the organic phase storage tank, and the organic phase enters the organic phase storage tank for storage; open the discharge valve of the organic phase storage tank and the feed valve of the concentration kettle, use a pump to pump the material into the concentration kettle, and then turn on the vacuum unit to evacuate the vacuum to maintain the pressure of the concentration kettle at 3 kPa; gradually heat the concentration kettle with low-pressure steam to evaporate the chloroform in the material. The final temperature of the concentration kettle is maintained at 39°C. Continue the concentration reaction for 5 hours to obtain a high-purity PCDL product.

[0048] 4) Solvent Recovery: The aqueous phase in the filtrate tank enters the aqueous phase storage tank and is then pumped back to the dissolution kettle via the aqueous phase reflux pump, achieving aqueous phase recycling. The chloroform solvent evaporated from the concentration kettle enters the crude chloroform tank via the concentration kettle cooler and is then pumped back to the dissolution kettle via the organic phase reflux pump, achieving solvent chloroform recycling.

[0049] Example 11

[0050] The difference from Example 10 is that: The mass ratio of crude PCDL: chloroform: pure water is 1:10:10; the temperature of the jacket hot water heating is 39°C; the temperature of the concentration kettle is controlled at 100°C and the vacuum degree is 30KPa.

[0051] Example 12

[0052] The difference from Example 10 is that: The mass ratio of crude PCDL: chloroform: pure water is 1:6:2; the temperature of the jacket hot water heating is 31°C; the temperature of the concentration kettle is controlled at 80°C and the vacuum degree is 10KPa.

[0053] The above embodiment of the present invention provides a method for purifying crude polycarbonate diol containing a titanate catalyst, the main advantages of which are: 1) By using crude PCDL with an organic solvent (such as DCM, THF, chloroform, or ethyl acetate) and pure water in a mass ratio of 1:1-10:1-10, the catalyst is effectively removed through dissolution, pressure filtration, static stratification, and concentration, yielding pure, catalyst-free PCDL. This method not only enables solvent and water recycling, simplifies the operational process, reduces environmental pollution and resource waste, but also promotes the purification and application of polycarbonate diols in industrial production.

[0054] 2) The residue collected from the dissolving kettle filter is primarily composed of solid titanium dioxide, formed by the reaction of a titanate catalyst with water. When sufficient quantities accumulate, this titanium dioxide can be sold as a product, generating additional revenue for the company.

[0055] 3) By optimizing the amounts of organic solvents such as DCM, THF, chloroform, and ethyl acetate, as well as pure water, and adjusting parameters such as the temperature and pressure of the dissolution vessel, the temperature of the concentration vessel, and the reaction time, large-scale production and purification of polycarbonate diol was achieved. This overcomes the limitation of existing technologies, which are only applicable to small-scale laboratory production, and significantly improves purification efficiency and yield.

[0056] 4) This invention has broad application prospects across multiple fields, including organic chemical synthesis, catalyst development, and polymer materials. Compared to existing technologies, it provides a more versatile method applicable to the production and purification of various types of polycarbonate diols, significantly enhancing its practical value.

[0057] 5) The technology of this invention can be applied not only to small-scale laboratory production and purification, but also to large-scale industrial production. Its flexibility allows it to be adjusted to meet the requirements of different production scales, with higher industrial application value and superiority over existing technologies.

[0058] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for purifying a crude polycarbonate diol containing a titanate catalyst, characterized in that: The following steps are involved: Step 1, select dichloromethane, chloroform, tetrahydrofuran or ethyl acetate as an organic solvent, and fully stir and dissolve the crude polycarbonate diol in a dissolving kettle at a mass ratio of crude polycarbonate diol: organic solvent: pure water = 1:1-10:1-10 under jacket hot water heating conditions; then, pass the mixed solution through a filter by means of high-purity nitrogen pressurization, collect the filtrate in a filtrate tank, and collect the filter residue in a dedicated storage tank; after the filtrate is allowed to stand and decompose, the separated organic phase and aqueous phase enter respective storage tanks; Step 2: The polycarbonate diol solution transferred from the organic phase storage tank enters the concentration kettle, and the dichloromethane, chloroform, tetrahydrofuran or ethyl acetate organic solvent is condensed and recovered by controlling the temperature and vacuum degree of the concentration kettle, and returned to the dissolution kettle for reuse; finally, the qualified polycarbonate diol product remaining in the concentration kettle enters the polycarbonate diol product tank for storage.

2. The method for purifying crude polycarbonate diol containing titanate catalyst according to claim 1, characterized in that: In step 1, the jacket is heated with hot water at a temperature of 25-39°C.

3. The method for purifying crude polycarbonate diol containing titanate catalyst according to claim 2, characterized in that: In step 1, the dissolving kettle is pressurized by high-purity nitrogen gas so that the pressure in the dissolving kettle is maintained at 0.5 MPa.

4. The method for purifying crude polycarbonate diol containing titanate catalyst according to claim 3, characterized in that: In step one, the filter residue mainly comprises titanium dioxide.

5. The method for purifying crude polycarbonate diol containing titanate catalyst according to claim 4, characterized in that: In step 1, the separated water phase is returned to the polycarbonate diol dissolving kettle through a water phase reflux pump for recycling.

6. The method for purifying crude polycarbonate diol containing titanate catalyst according to claim 5, characterized in that: In step 1, the organic solvent evaporated from the concentration kettle enters the crude product tank through the concentration kettle cooler, and then returns to the polycarbonate diol dissolution kettle through the organic phase reflux pump for recycling.

7. The method for purifying crude polycarbonate diol containing titanate catalyst according to any one of claims 1 to 6, characterized in that: In step 2, the temperature of the concentration kettle is controlled to be 39-100° C. and the vacuum degree is controlled to be 3-30 KPa.

Images