A method for catalytic degradation of polycarbonate using a phosphazene base system
By using a phosphazene alkaline catalyst to catalytically degrade polycarbonate to produce bisphenol A and substituted diphenyl carbonate, the problem of metal catalyst pollution is solved, and efficient green chemical recycling is achieved with high product yield.
Patent Information
- Application Number
- CN202311010618.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-11
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2043-08-11
AI Technical Summary
Existing chemical recycling methods for waste polycarbonate typically use metal catalysts, which lead to contamination of polymer monomers, and lack green and pollution-free degradation methods.
A phosphazene base system was used as a catalyst, with tert-butyl-substituted phosphazene base and substituted phenol as reaction reagents. Polycarbonate was catalytically degraded at high temperature and atmospheric pressure to produce bisphenol A and substituted diphenyl carbonate. The products were neutralized and fractionated using a Sigma acidic molecular sieve column during the post-treatment process.
It achieves green chemical recycling without the participation of metal catalysts, reduces pollution to polymer monomers, achieves product yield of over 90%, and simplifies post-processing steps.
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Abstract
Description
Technical Field
[0001] This invention relates to a method for the catalytic degradation of polycarbonate using a phosphazene alkaline system, belonging to the field of organic material chemical recycling technology. Background Technology
[0002] Polycarbonate (PC) is a thermoplastic engineering plastic with excellent comprehensive properties, including good mechanical, optical, thermal and flame retardant properties. It is widely used in many fields such as automotive parts, consumer electronics, electronic engineering, home appliances, light-emitting diodes, building materials, and durable consumer goods.
[0003] Polycarbonate is also a durable thermoplastic engineering material. From a recycling perspective, "durable" corresponds to reusability, "thermoplastic" corresponds to easy recycling, and "engineering" corresponds to high-value recycling, which aligns with the circular economy and the recycling of plastics. However, existing methods for chemically recycling waste polycarbonate typically use metal catalysts to catalyze the degradation of polycarbonate, which pollutes the original polymer monomers. There is an urgent need for a green, pollution-free, and metal-free degradation method for the chemical recycling of polycarbonate. Summary of the Invention
[0004] This invention addresses the common practice in existing chemical recycling of waste polycarbonate by using metal catalysts to catalyze its degradation. It provides a method for catalytically degrading polycarbonate using an organophosphorus alkali system. Specifically, it utilizes organophosphorus alkalis to achieve the chemical recycling of waste polycarbonate. No metal catalyst is added during the reaction, which helps reduce metal contamination of the polymer monomers, reduces post-processing steps, and achieves green chemical recycling.
[0005] The technical solution of the present invention:
[0006] One of the objectives of this invention is to provide a method for catalytic degradation of polycarbonate using a phosphazene base system. This method involves using a tert-butyl-substituted phosphazene base as a catalyst and substituted phenol as a reaction reagent under high temperature and normal pressure conditions to catalytically degrade polycarbonate, thereby obtaining a depolymerization solution containing bisphenol A and substituted diphenyl carbonate.
[0007] Further specifying, the tert-butyl substituted phosphazene base is one or more of the following structural formulas;
[0008]
[0009] Further specified, the amount of catalyst used is 1 to 5 wt% of polycarbonate.
[0010] Further, the degradation temperature is specified as 100–200℃, and the time is specified as 5–10 hours.
[0011] Further specifying, the substituted phenol is one or a mixture of phenol, o-cresol, and p-cresol.
[0012] Further specified, the molar ratio of the substituted phenol to the polycarbonate repeating unit is (2-10):1.
[0013] Further specifying the post-treatment method for the depolymerization solution, the depolymerization solution is neutralized by passing it through a Sigma acidic molecular sieve column, and then the excess substituted phenol, substituted diphenyl carbonate and bisphenol A are separated by fractional distillation.
[0014] Further specified, the fractionation temperature is above 230℃.
[0015] Further specified, the yield of bisphenol A is above 90%.
[0016] Further specified, the yield of the product replacing diphenyl carbonate is over 90%.
[0017] The advantages of this invention compared to the prior art are as follows:
[0018] This invention uses tert-butyl-substituted phosphazene base as a catalyst and substituted phenol as a reaction reagent. Under the catalysis of the phosphazene base catalyst, phenol attacks the polycarbonate molecular chain and undergoes depolymerization to obtain the products bisphenol A and substituted diphenyl carbonate. No metal catalyst is added during the reaction, which helps to reduce metal pollution to the polymer monomers, reduce post-processing steps, achieve green chemical recycling, and the product yield is over 90%. Detailed Implementation
[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.
[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.
[0023] The polycarbonate (PC) pellets used in the following examples were purchased from Sigma-Aldrich and have a molecular weight of 21 kg / mol and a molecular weight distribution of 1.25.
[0024] Example 1
[0025]
[0026] A. Depolymerization: The purchased PC granules were heated at 150°C and standard atmospheric pressure with t-BuP1 as a catalyst, the amount of which was 3.3 wt% of the PC granules. Four equivalents of phenol were added, and the reaction time was 8 hours, causing the PC molecular chains to break down and depolymerize, resulting in a depolymerization solution containing the degradation products bisphenol A and diphenyl carbonate.
[0027] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0028] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 240℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 95%, and the yield of diphenyl carbonate was 96.3%.
[0029] Example 2
[0030]
[0031] A. Depolymerization: The purchased PC granules are heated at 140°C and standard atmospheric pressure with t-BuP2 as a catalyst, the amount of which is 3 wt% of the PC granules. Four equivalents of phenol are added, and the reaction time is 8 hours, causing the PC molecular chains to break down and depolymerize, obtaining a depolymerization solution containing the degradation products bisphenol A and diphenyl carbonate.
[0032] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0033] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 240℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 96%, and the yield of diphenyl carbonate was 95.8%.
[0034] Example 3
[0035]
[0036] A. Depolymerization: The purchased PC granules were subjected to depolymerization at 140°C and standard atmospheric pressure, using t-BuP4 as a catalyst at a mass fraction of 2 wt% of the PC granules. Four equivalents of phenol were added, and the reaction was carried out for 8 hours to break down the PC molecular chains and obtain the degradation products bisphenol A and diphenyl carbonate.
[0037] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0038] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 250℃. Excess phenol and product bisphenol A were distilled off. Finally, the yield of bisphenol A was 99%, and the yield of diphenyl carbonate was 99.3%.
[0039] Example 4
[0040]
[0041] A. Depolymerization: The purchased PC granules were subjected to depolymerization at 140°C and standard atmospheric pressure, using t-BuP2 and t-BuP4 as composite catalysts (the mass ratio of P2 to P4 was 1:1), with the catalyst amount being 4 wt% of the PC granules. Two equivalents of phenol were added, and the reaction time was 8 hours, causing the PC molecular chains to break down and depolymerize, yielding a depolymerization solution containing the degradation products bisphenol A and diphenyl carbonate.
[0042] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0043] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 250℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 96%, and the yield of diphenyl carbonate was 95.8%.
[0044] Example 5
[0045]
[0046] A. Depolymerization: The purchased PC granules were heated at 140°C and standard atmospheric pressure with t-BuP1 as a catalyst, the amount of which was 1.5 wt% of the PC granules. Four equivalents of o-phenol were added, and the reaction time was 10 h, which caused the PC molecular chains to break down and depolymerize, obtaining a depolymerization solution containing the degradation products bisphenol A and di-o-toluene carbonate.
[0047] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0048] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 97%, and the yield of di-o-toluene carbonate was 95.2%.
[0049] Example 6
[0050]
[0051] A. Depolymerization: The purchased PC granules are heated at 200°C and standard atmospheric pressure, using t-BuP2 as a catalyst at a mass fraction of 5 wt% of the PC granules. Four equivalents of o-phenol are added, and the reaction time is 5 hours, causing the PC molecular chains to break down and depolymerize, resulting in a depolymerization solution containing the degradation products bisphenol A and di-o-toluene carbonate.
[0052] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0053] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 90.2%, and the yield of di-o-toluene carbonate was 91.3%.
[0054] Example 7
[0055]
[0056] A. Depolymerization: The purchased PC granules are heated at 180°C and standard atmospheric pressure with t-BuP4 as a catalyst, the amount of catalyst added being 2 wt% of the PC granules. Six equivalents of o-phenol are added, and the reaction time is 5 hours, causing the PC molecular chains to break down and depolymerize, obtaining a depolymerization solution containing the degradation products bisphenol A and di-o-toluene carbonate.
[0057] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0058] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 90.2%, and the yield of di-o-toluene carbonate was 91.3%.
[0059] Example 8
[0060]
[0061] A. Depolymerization: The purchased PC granules were subjected to depolymerization at 150°C and standard atmospheric pressure, using t-BuP2 and t-BuP4 as catalysts (the ratio of composite catalyst P1:P4 was 1:3), with the catalyst amount being 4 wt% of the PC granules. Four equivalents of o-phenol were added, and the reaction time was 7 hours, causing the PC molecular chains to break down and depolymerize, yielding a depolymerization solution containing the degradation products bisphenol A and di-o-toluene carbonate.
[0062] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0063] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 98.2%, and the yield of di-o-toluene carbonate was 98%.
[0064] Example 9
[0065]
[0066] A. Depolymerization: The purchased PC granules were heated at 160°C and standard atmospheric pressure with t-BuP1 as a catalyst, the amount of which was 2 wt% of the PC granules. Four equivalents of p-cresol were added, and the reaction time was 8 hours, causing the PC molecular chains to break down and depolymerize, yielding a depolymerization solution containing the degradation products bisphenol A and di-p-toluene carbonate.
[0067] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0068] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 250℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 96%, and the yield of di-p-toluene carbonate was 93%.
[0069] Example 10
[0070]
[0071] A. Depolymerization: The purchased PC granules were heated at 170°C and standard atmospheric pressure, using t-BuP2 as a catalyst at a mass fraction of 3 wt% of the PC granules. Four equivalents of p-cresol were added, and the reaction time was 7 hours, causing the PC molecular chains to break down and depolymerize, yielding a depolymerization solution containing the degradation products bisphenol A and di-p-toluene carbonate.
[0072] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0073] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 96.2%, and the yield of di-p-toluene carbonate was 96.2%.
[0074] Example 11
[0075]
[0076] A. Depolymerization: The purchased PC granules are heated at 190°C and standard atmospheric pressure with t-BuP4 as a catalyst, the amount of catalyst added being 2 wt% of the PC granules. Six equivalents of p-cresol are added, and the reaction time is 5 hours, causing the PC molecular chains to break down and depolymerize, yielding a depolymerization solution containing the degradation products bisphenol A and di-p-toluene carbonate.
[0077] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0078] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 98%, and the yield of di-o-toluene carbonate was 93.6%.
[0079] Example 12
[0080]
[0081] A. Depolymerization: The purchased PC granules were subjected to depolymerization at 150°C and standard atmospheric pressure, using t-BuP2 and t-BuP1 as catalysts (the mass ratio of the composite catalyst P1:P4 was 2:3), with the catalyst amount being 5 wt% of the PC granules. Four equivalents of p-cresol were added, and the reaction time was 8 hours, causing the PC molecular chains to break down and depolymerize, yielding a depolymerization solution containing the degradation products bisphenol A and di-p-toluene carbonate.
[0082] B. Neutralization: The depolymerized solution is neutralized by acid-base reaction by passing the solution through a Sigma acidic molecular sieve column to neutralize the alkaline catalyst in the solution.
[0083] C. Separation: The filtered solution was placed in a distillation column and the temperature was set to 260℃. Excess phenol and product bisphenol A were distilled off. The final yield of bisphenol A was 92.2%, and the yield of di-p-toluene carbonate was 94%.
[0084] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.
Claims
1. A method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system, characterized in that, Under high temperature and normal pressure conditions of 100 ~ 200℃, tert-butyl substituted phosphazene base is used as a catalyst and substituted phenol is used as a reaction reagent to catalytically degrade polycarbonate and obtain a depolymerization solution containing bisphenol A and substituted diphenyl carbonate. The molar ratio of the added substituted phenol to the polycarbonate repeating unit is (2 ~ 10):1; The tert-butyl-substituted phosphazene base is one or more of the following structural formulas; ； The catalyst dosage is 1 to 5 times the amount of polycarbonate. wt %.
2. The method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system according to claim 1, characterized in that, The degradation time is 5 to 10 hours.
3. The method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system according to claim 1, characterized in that, The substituted phenol is one or a mixture of phenol, o-cresol, and p-cresol.
4. The method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system according to claim 1, characterized in that, After the depolymerization solution was neutralized by passing it through a Sigma acidic molecular sieve column, excess substituted phenols, substituted diphenyl carbonates, and bisphenol A were separated by fractional distillation.
5. The method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system according to claim 4, characterized in that, The fractionation temperature is above 230℃.
6. The method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system according to claim 1, characterized in that, The yield of bisphenol A was over 90%.
7. The method for catalytic degradation of polycarbonate using a phosphazene-based alkaline system according to claim 1, characterized in that, The yield of the product that replaces diphenyl carbonate is over 90%.