Halogenated salt catalyzed polyester plastic degradation method
By using halide salt catalysts in alcohol or amine solvents, combined with oil bath heating or microwave-assisted methods, the efficient degradation of polyester plastics into corresponding monomers under mild conditions was achieved, solving the problem of requiring auxiliary solvents or high-temperature conditions in existing technologies. This method features high yield and environmental friendliness.
Patent Information
- Application Number
- CN202511007501.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-22
- Publication Date
- 2025-11-07
AI Technical Summary
Existing technologies cannot achieve efficient degradation of polyester plastics into corresponding monomers under mild conditions in alcohol solvents, and existing methods require auxiliary solvents or high-temperature conditions.
Using halide salts as catalysts, selective degradation of polyester plastics is achieved in alcohol or amine solvents at 80–250°C via oil bath heating or microwave-assisted methods.
It achieves efficient degradation of polyester plastics into corresponding monomers under mild conditions, with high degradation yield, simple reaction system, environmental friendliness, and mild degradation conditions.
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Figure CN120904017A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the field of high polymer materials, and particularly relates to a degradation method of polyester plastics. BACKGROUND
[0002] Plastic products have become an indispensable basic material in modern society. According to research statistics, the current global plastic annual output has exceeded 500 million tons, and the historical cumulative output has exceeded 9 billion tons. However, only about 20% of the waste plastics can be recycled, and the rest mostly end up in landfills or natural ecosystems. With the continuous rise in plastic consumption, the pollution problem caused by it is continuing to intensify. Improper disposal of plastic waste not only causes serious environmental pollution, but also poses a potential threat to human health. Therefore, it is crucial to achieve efficient management and recycling of waste plastics. The current ways of plastic recycling and reuse are mainly: melt re-plasticization, mechanical recycling, energy utilization, and chemical degradation. Among them, the melt re-plasticization method is only suitable for the production of offcuts during the production of products, and is not suitable for the treatment of waste plastics in household garbage. The mechanical recycling method is relatively simple to operate, but the plastics need to be strictly classified before recycling, which will significantly increase the overall cost. In addition, during the recycling process, the plastic materials inevitably undergo mechanical stress, causing damage to their molecular structure and gradual degradation of their performance, affecting the recycling. The energy recycling method is to convert plastics into usable heat energy through incineration, but it will inevitably produce carbon dioxide and other waste. Chemical degradation not only can achieve the complete conversion of plastics into corresponding monomers or related high-value products, but also can avoid the emission of carbon dioxide.
[0003] Poly(bisphenol A carbonate) (PC) is an engineering plastic with rapidly growing production, excellent mechanical strength, thermal stability and durability, which is widely used in electronics and other industries. The alcoholysis and hydrolysis strategies have been developed for the chemical recycling of poly(bisphenol A carbonate). Compared with the hydrolysis strategy, PC alcoholysis can avoid the release of carbon dioxide and has attracted widespread attention. However, due to the poor solubility of polycarbonate (PC) in alcohol solvents and the relatively weak nucleophilicity of alcohol, the alcoholysis reaction usually needs to be carried out under harsh high temperature conditions (> 200℃). Therefore, the current method is to introduce auxiliary solvents such as N,N-dimethylformamide (DMF) to improve the solubility of polycarbonate (PC) in alcohol, and then promote its degradation (Progress in Polymer Science, 2024, 149, 101783). However, the introduction of auxiliary solvents increases the complexity of the reaction system and significantly increases the difficulty of product separation. In the system without auxiliary solvents, although some studies have achieved the degradation of poly(bisphenol A carbonate) in ethylene glycol using zinc acetate as a catalyst (Polymer Degradation and Stability, 2023, 207, 110210), this method still requires high temperature conditions of 180℃, which has high energy consumption and operation cost. In summary, it is still urgent to develop a new method that relies only on alcohol solvents and achieves efficient degradation of plastics to monomers under milder conditions. The present invention proposes an innovative strategy: under oil bath heating or microwave assistance, simple halide salt is used as a catalyst to efficiently degrade polycarbonate plastics to the corresponding monomers in a pure alcohol solvent system. SUMMARY
[0004] The purpose of the present invention is to provide a method for selectively degrading polyester plastics to corresponding monomers and derivatives using halide salt as a catalyst, which is simple in conditions and convenient to operate.
[0005] The present invention provides a halide salt catalyzed polyester plastic degradation method, which uses halide salt as a catalyst to degrade polycarbonate plastics in alcohol solvents or amine solvents to obtain corresponding polymer monomer molecules or their derivatives; the conditions are: under oil bath heating or microwave action, the reaction temperature is 80-250℃, and the closed reaction is 5 minutes-48 hours.
[0006] In the present invention, the halide salt is fluorinated salt, chlorinated salt, iodized salt or brominated salt. For example: sodium fluoride, sodium chloride, sodium bromide, sodium iodide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cesium chloride, rubidium chloride, magnesium chloride, calcium chloride, barium chloride, aluminum chloride, iron chloride, cobalt chloride, copper chloride, zinc chloride.
[0007] In the present application, the polyester plastics include one or more of poly(bisphenol A carbonate), polypropylene carbonate, poly(1,3-propanediol carbonate), polyvinyl alcohol carbonate, polytrimethylene carbonate, polybutylene carbonate, polypropylene carbonate glycol, polylactic acid, polyethylene terephthalate, polybutylene succinate.
[0008] In the present application, the alcohol solvent mainly includes primary alcohol and secondary alcohol, such as methanol, ethanol, propanol, butanol, isopropanol, benzyl alcohol, phenethyl alcohol, ethylene glycol, propylene glycol, and ethylene glycol monomethyl ether. The amine solvent includes primary amine and secondary amine, such as n-butylamine, benzylamine, isobutylamine, diethylamine, dibutylamine, and diisopropylamine. The amount of the amine solvent is 0.5 mL to 2 mL.
[0009] In the present application, the amount of the catalyst is 1 to 50 mol% (preferably 4 to 20 mol%, and more preferably 5 mol%) of the substrate. The calculation method of the amount of substance of the substrate is the total mass of the polymer divided by the molar mass of the repeating unit of the polymer.
[0010] In the present application, the oil bath heating is at a temperature of 80 to 200 ℃, preferably at a temperature of 130 to 150 ℃, and more preferably at a temperature of 150 ℃. The reaction time is 40 minutes to 30 hours, preferably 15 to 25 hours, and more preferably 24 hours.
[0011] In the present application, the microwave is at a power of 50 W, a reaction temperature of 100 to 250 ℃, preferably a temperature of 120 to 180 ℃, and more preferably a temperature of 150 ℃. The reaction time is 5 minutes to 48 hours, preferably 1 to 4 hours, and more preferably 4 hours.
[0012] In the present application, the polyester can be chemically degraded into monomers of the corresponding polymer in an alcohol solvent or an amine solvent under the action of oil bath heating or microwaves without an auxiliary solvent.
[0013] In the present application, the halogenated salt is used as the catalyst to achieve the high-selectivity degradation of the polyester plastics. The method has the characteristics of environmental friendliness, simple reaction system, and simple raw materials.
[0014] Compared with the existing technology, the present application has the following advantages:
[0015] (1) The present application realizes the selective degradation of the polyester plastics using a simple halogenated salt as the catalyst for the first time.
[0016] (2) The present application does not need an auxiliary solvent, and the degradation of the polyester plastics can be realized using only an alcohol solvent or an amine solvent. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum of the degradation product bisphenol A of poly(bisphenol A carbonate) in the examples. DETAILED DESCRIPTION
[0018] The application is further described by the following examples.
[0019] The materials involved in the examples can be obtained from commercial channels.
[0020] The method for detecting degradation products in the application is nuclear magnetic resonance hydrogen spectrum.
[0021] The method for calculating the yield of degradation products in the application is as follows:
[0022]
[0023] Example 1: Degradation of polybisphenol A carbonate with halide as catalyst (oil bath heating)
[0024]
[0025] In a 15 mL sealed tube, polybisphenol A carbonate (1 mmol), catalyst Cat. (0.2 mmol), and ethanol (EtOH, 2 mL) were sequentially added. The reaction tube was sealed and placed in an oil bath for reaction at 150°C for 24 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain a crude product, which was purified by column chromatography to obtain the product bisphenol A, and the product was dried under vacuum. Figure 1 The nuclear magnetic resonance hydrogen spectrum of the degradation product bisphenol A.
[0026] Cat. NaCl NaBr NaI LiCl KCl Yield 96％ 92％ 90％ 96％ 84％ Cat. MgCl2 CaCl2 ZnCl2 CsCl Yield 97％ 91％ 97％ 97％
[0027] The catalyst used in the following examples is sodium chloride.
[0028] Example 2: Degradation of polybutylene succinate with sodium chloride as catalyst (oil bath heating)
[0029]
[0030] In a 15 mL sealed tube, polybutylene succinate (1 mmol), sodium chloride (NaCl, 0.2 mmol), and anhydrous ethanol (2 mL) were sequentially added. The sealed tube was placed in an oil bath for reaction at 150°C for 24 h, and then cooled to room temperature. Trimethoxybenzene (0.3 mmol) was added as an internal standard, and after stirring uniformly, a sample was taken for detection by nuclear magnetic hydrogen spectrum, and the yield of diethyl succinate was calculated to be 82%.
[0031] Example 3: Degradation of polybisphenol A carbonate with methanol as solvent (oil bath heating)
[0032]
[0033] In a 15 mL sealed tube, polyethylene glycol (1 mmol), NaCI (0.2 mmol), anhydrous methanol (2 mL) were added in sequence. The sealed tube was closed and placed in an oil bath at 150 °C for 24 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain the product, polyethylene glycol, which was dried under vacuum. The yield was calculated to be 95% after weighing. Figure 1 The nuclear magnetic resonance hydrogen spectrum of the degradation product, polyethylene glycol, was obtained.
[0034] Example 4: Degradation of polylactic acid with sodium chloride as catalyst (oil bath heating)
[0035]
[0036] In a 15 mL sealed tube, polylactic acid (1 mmol), NaCI (0.2 mmol), anhydrous methanol (2 mL) were added in sequence. The sealed tube was closed and placed in an oil bath at 150 °C for 24 hours. After cooling to room temperature, mesitylene (0.3 mmol) was added as an internal standard, and the sample was stirred uniformly. The yield of methyl lactate was calculated to be 96% by nuclear magnetic resonance hydrogen spectrum.
[0037] Example 4: Degradation of polylactic acid with sodium chloride as catalyst (oil bath heating)
[0038]
[0039] In a 15 mL sealed tube, polylactic acid (1 mmol), NaCI (0.2 mmol), anhydrous methanol (2 mL) were added in sequence. The sealed tube was closed and placed in an oil bath at 150 °C for 24 hours. After cooling to room temperature, mesitylene (0.3 mmol) was added as an internal standard, and the sample was stirred uniformly. The yield of methyl lactate was calculated to be 96% by nuclear magnetic resonance hydrogen spectrum.
[0040] Example 5: Degradation of polyethylene glycol carbonate with benzylamine as solvent (oil bath heating)
[0041]
[0042] In a 15 mL sealed tube, polyethylene glycol (1 mmol), NaCI (0.2 mmol), anhydrous methanol (2 mL) were added in sequence. The sealed tube was closed and placed in an oil bath at 150 °C for 24 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain the product, polyethylene glycol, which was dried under vacuum. The yield was calculated to be 95% after weighing. Figure 1 The nuclear magnetic resonance hydrogen spectrum of the degradation product, polyethylene glycol, was obtained.
[0043] Example 6: Degradation of poly(bisphenol A carbonate) with benzylamine as solvent (oil bath heating)
[0044]
[0045] In a 15 mL sealed tube, poly(bisphenol A carbonate) (1 mmol), catalyst sodium chloride (0.2 mmol), and benzylamine (2 mL) were added in sequence. The reaction tube was sealed and placed in an oil bath at 150 °C for 12 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain the product bisphenol A. The product bisphenol A was dried under vacuum, and the yield was calculated to be 86% after weighing. Figure 1 The nuclear magnetic resonance hydrogen spectrum of the degradation product bisphenol A was determined.
[0046] Example 7: Degradation of poly(bisphenol A carbonate) with n-butylamine as solvent (microwave heating)
[0047]
[0048] In a 15 mL sealed tube, poly(bisphenol A carbonate) (1 mmol), catalyst sodium chloride (0.2 mmol), and n-butylamine (2 mL) were added in sequence. The reaction tube was sealed and placed in a microwave reactor with a power of 50 W and a temperature setting of 80 °C for 1 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain the product bisphenol A. The product bisphenol A was dried under vacuum, and the yield was calculated to be 92% after weighing. Figure 1 The nuclear magnetic resonance hydrogen spectrum of the degradation product bisphenol A was determined.
[0049] Example 8: Degradation of poly(bisphenol A carbonate) with ethanol as solvent (microwave heating)
[0050]
[0051] In a 15 mL sealed tube, poly(bisphenol A carbonate) (1 mmol), catalyst sodium chloride (0.2 mmol), and ethanol (2 mL) were added in sequence. The reaction tube was sealed and placed in a microwave reactor with a power of 50 W and a temperature setting of 160 °C for 4 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain the crude product, which was purified by column chromatography to obtain the product bisphenol A. The product bisphenol A was dried under vacuum, and the yield was calculated to be 76% after weighing. Figure 1 The nuclear magnetic resonance hydrogen spectrum of the degradation product bisphenol A was determined.
Claims
1. A method for the degradation of polyester plastics catalyzed by halogenated salts, characterized by, The polyester plastic is degraded in alcohol solvent or amine solvent with halide salt as catalyst to obtain corresponding polymer monomer molecule or its derivative; the reaction temperature is 80-250 DEG C under oil bath heating or microwave action, and the reaction time is 5 minutes-48 hours in a closed reaction.
2. The polyester plastic degradation method according to claim 1, wherein, The halide salt is fluorinated salt, chlorinated salt, iodized salt or brominated salt.
3. The polyester plastic degradation method according to claim 2, wherein, The halide salt is sodium fluoride, sodium chloride, sodium bromide, sodium iodide, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, cesium chloride, rubidium chloride, magnesium chloride, calcium chloride, barium chloride, aluminum chloride, iron chloride, cobalt chloride, copper chloride or zinc chloride.
4. The polyester plastic degradation method according to claim 2, wherein, The polyester plastic is polybisphenol A carbonate, polypropylene carbonate, poly-1,3-propanediol carbonate, polyvinyl alcohol carbonate, polytrimethylene carbonate, polybutylene carbonate, polypropylene carbonate glycol, polylactic acid, polyethylene terephthalate or polybutylene succinate.
5. The polyester plastic degradation method according to claim 2, wherein, The alcohol solvent is selected from methanol, ethanol, propanol, butanol, isopropanol, benzyl alcohol, phenethyl alcohol, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether; the amine solvent is selected from n-butylamine, benzylamine, isobutylamine, diethylamine, dibutylamine, diisopropylamine; the solvent is used in an amount of 0.5 mL-2 mL.
6. The polyester plastic degradation method according to claim 2, wherein, The catalyst is used in an amount of 1-50 mol% of the substrate, and the calculation method of the amount of substance of the substrate is the total mass of the polymer divided by the molar mass of the polymer repeating unit.
7. The polyester plastic degradation method according to claim 2, wherein, The oil bath heating is carried out at a reaction temperature of 80-200 DEG C for a reaction time of 40 minutes-30 hours.
8. The polyester plastic degradation method according to claim 2, wherein, The microwave assistance is carried out at a microwave power of 50 W, a reaction temperature of 100-250 DEG C and a reaction time of 5 minutes-4 hours.