A method for the high-value recycling of polycarbonate waste

Abstract

The present invention discloses a method for the high-value recycling and utilization of polycarbonate waste, belonging to the technical field of solid waste recycling and utilization, and comprising the following steps: constructing a reaction system by using pulverized bisphenol A polycarbonate waste, o-phenylenediamine compounds, and an ionic liquid catalyst, and placing the reaction system at a temperature of 100-150 °C in an air atmosphere for a reaction of ≥30 min to obtain products bisphenol A and benzimidazolone compounds; the method of the present invention realizes the simultaneous recovery of two monomers, bisphenol A and benzimidazolone compounds, and has high reaction efficiency in a one-step process. The reaction can be carried out under normal pressure and solvent-free conditions, and can make full use of the carbon resources in polycarbonate waste, and has broad application prospects in the recycling and utilization of waste plastics.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste recycling and utilization, and specifically relates to a method for the high-value recycling and utilization of polycarbonate waste materials. Background Art

[0002] Polycarbonate is an amorphous thermoplastic with excellent physical, chemical, and processing properties, such as high strength, impact resistance, chemical corrosion resistance, high transparency, etc., and occupies an important position in the engineering plastics market. Polycarbonate can be used to manufacture food and beverage containers, protective equipment, industrial safety baffles, insulating connectors, electrical appliance housings, etc., and has extensive applications in fields such as optical instruments, automotive industry, construction industry, electronic products, medical field, packaging industry, aerospace, etc. However, with the large-scale production and use of polycarbonate products, the problem of their disposal after being discarded has become increasingly urgent. If untreated polycarbonate waste materials directly enter the environment, they will pollute the soil and water bodies and affect the ecological environment. Therefore, it is necessary to develop high-value recycling and utilization strategies for polycarbonate waste materials to achieve resource reuse and reduce the risk of ecological environmental pollution.

[0003] Researchers have developed various strategies for the recycling and utilization of polycarbonate, such as hydrolysis process, alcoholysis process, glycolysis process, pyrolysis process, etc., to convert polycarbonate into high-value chemical monomers. For example, the published patent numbers CN111484395A and CN106748665A disclose the methanol alcoholysis method of polycarbonate. The corresponding method is green and mild, and the C-O bond is broken by attacking the carbonate bond (-O-C(=O)-O-) with methanol, ethanol, etc. to obtain the monomer bisphenol A. The published patent numbers CN117986094A and CN118791367A disclose the conversion of polycarbonate into monomers such as bisphenol A dimethyl ether using an alkylating agent (such as dimethyl carbonate) as the methyl source and the action of a specific catalyst. Usually, only a single chemical monomer is obtained in the above reactions, and the full and effective utilization of carbon resources is not achieved.

[0004] Benzimidazolone is a derivative of benzimidazole. Due to its unique structural feature - the combination of the benzimidazole ring system and the carbonyl group, this type of compound has high stability and a wide range of biological activities (such as antibacterial, anticancer, and anti-inflammatory effects), and is of great significance in medicinal chemistry. In addition to its pharmacological importance, benzimidazolone-based heterocyclic compounds also have good application prospects in fields such as materials science and catalysis. In the prior art, there is no report on the synthesis of benzimidazolone and its derivatives using waste polycarbonate. Summary of the Invention

[0005] The present invention provides a method for the high-value recycling and utilization of polycarbonate waste. By introducing o-phenylenediamine or its derivatives, the recycling of two monomers, namely bisphenol A and benzimidazolone compounds, is achieved. The reaction can be carried out under normal pressure and solvent-free conditions, and two chemical monomers can be prepared in one step reaction, enabling the full utilization of carbon resources in polycarbonate waste.

[0006] The specific technical solution adopted is as follows:

[0007] A method for the high-value recycling and utilization of polycarbonate waste, comprising the following steps:

[0008] Using crushed bisphenol A polycarbonate waste, o-phenylenediamine compounds, and an ionic liquid catalyst to construct a reaction system. Under an air atmosphere, the reaction system is placed at a temperature of 100-150 °C for a reaction of ≥30 min to obtain the products bisphenol A and benzimidazolone compounds;

[0009] The structural formula of the o-phenylenediamine compounds is as follows; where R 1 、R 2 are each independently selected from hydrogen, methyl, methoxy or halogen;

[0010] ;

[0011] The structural formula of the ionic liquid catalyst is:

[0012] 。

[0013] The present invention selects a specific ionic liquid catalyst to construct a reaction system containing bisphenol A polycarbonate waste, o-phenylenediamine compounds, and an ionic liquid catalyst. Without the addition of organic solvents, the full depolymerization of polycarbonate can be achieved under an air atmosphere and normal pressure, and benzimidazolone compounds can be prepared simultaneously, realizing the upgrading transformation of bisphenol A polycarbonate waste into two high-value chemical monomers in one step.

[0014] Preferably, the bisphenol A polycarbonate waste includes but is not limited to PC plates, sheets, pipes, films, etc. Of course, pure polycarbonate can also be used. The method of the present invention is applicable to the recycling and upgrading of various forms of bisphenol A polycarbonate waste, showing excellent efficiency and adaptability.

[0015] Preferably, the o-phenylenediamine compounds are at least one of the following compounds:

[0016] 。

[0017] By using different o-phenylenediamine compounds, different benzimidazoles or their derivatives can be obtained. The benzimidazolone compounds are at least one of the following compounds:

[0018] 。

[0019] Optionally, in the reaction system, water is further included, and the feeding amount ratio of water to the bisphenol A polycarbonate waste is 0.01 - 0.05 g:1 mmol. The method of the present invention can be successfully carried out under solvent-free conditions or in the presence of trace water.

[0020] Preferably, the molar ratio of the bisphenol A polycarbonate waste to the o-phenylenediamine compound is 1:1 - 5.

[0021] Preferably, the molar ratio of the bisphenol A polycarbonate waste to the ionic liquid catalyst is 1:0.06 - 0.50.

[0022] Most preferably, the molar ratio of the bisphenol A polycarbonate waste to the o-phenylenediamine compound is 1:1 - 3, and the molar ratio of the bisphenol A polycarbonate waste to the ionic liquid catalyst is 1:0.20 - 0.50. Under the above condition parameters, the product bisphenol A and benzimidazolone compounds can be prepared in high yield, which helps the ionic liquid catalyst to play a role and achieve full conversion of raw materials, and effectively utilize the carbon resources in the bisphenol A polycarbonate.

[0023] Preferably, the reaction conditions are a temperature of 110 - 130 °C and a time of 0.5 - 6 h.

[0024] The yield of bisphenol A obtained by the method for the high-value recycling of the polycarbonate waste is ≥56%, preferably ≥89%, and most preferably ≥99%; the yield of benzimidazolone compounds is ≥65%, preferably ≥75%, and most preferably ≥95%.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) By constructing a specific reaction system, the method for recycling polycarbonate waste developed by the present invention is carried out under an air atmosphere, normal pressure, and solvent-free (or in the presence of trace water) conditions. The reaction conditions are simple and mild, the reaction rate is relatively fast, the types of raw materials are few, the carbon resources in the bisphenol A polycarbonate can be fully utilized, turning waste into treasure, being green and environmentally friendly, realizing the double upgrading transformation of waste plastic resources, and simultaneously preparing two chemical monomers, bisphenol A and benzimidazolone compounds, in one step. Moreover, bisphenol A and benzimidazolone compounds are easy to separate, and these two reaction products can be further used for synthesizing functional chemical substances.

[0027] (2) The method of the present invention can realize further expansion of reaction products, not only limited to benzimidazolone, but also various benzimidazolone derivatives can be prepared. Description of the Drawings

[0028] Figure 1 It is the reaction roadmap for the high-value recycling of polycarbonate waste in Example 1.

[0029] Figure 2 It is the 1H NMR spectrum (deuterated chloroform) of the product bisphenol A.

[0030] Figure 3 It is the 1H NMR spectrum (deuterated chloroform) of the product benzimidazolone. Detailed implementation manners

[0031] To make the objectives, features, and advantages of the present invention more obvious and understandable, the following provides a detailed description through specific implementation manners. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined correspondingly without conflict.

[0032] For the operation methods without specific conditions indicated in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. The experimental materials used in the following examples can be obtained from conventional biochemical reagent companies without special instructions.

[0033] The reaction processes of the following examples and comparative examples are all carried out under atmospheric pressure conditions. Atmospheric pressure generally refers to 0.09 - 0.11 MPa, without applying additional pressure; the structural formula of the ionic liquid catalyst used is: , which can be synthesized according to the literature records; the polycarbonates are all bisphenol A type polycarbonates.

[0034] Comparative Example 1

[0035] Add 0.254 g of polycarbonate powder with a CR purity (1 mmol), 2 mmol of o-phenylenediamine, 0.4 mmol of 1,8-diazabicyclo[5.4.0]undec-7-ene, 0.02 g of water, and 2 mL of N N-methylpyrrolidone into a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller. After placing the pressure-resistant tube reactor, start stirring and heating. The reaction system is heated to 130 °C and reacted at this temperature for 4 hours. After the reaction is completed, cool it to room temperature, and the obtained mixed solution is the product. Take 50 μL of the obtained mixed solution, add 600 μL of deuterated DMSO, and measure the yield through a nuclear magnetic resonance spectrometer. The results show that the yield of bisphenol A is 99%, and the yield of benzimidazolone is 48%.

[0036] Comparative Example 2

[0037] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with a CR purity (1 mmol), 2 mmol of o-phenylenediamine, 0.4 mmol of ionic liquid catalyst, and 2 mL N of N-methylpyrrolidone were added. After placing the pressure-resistant tube reactor, stirring and heating were started. The reaction system was heated to 130 °C and reacted at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to room temperature, and the resulting mixed solution was the product. 50 μL of the resulting mixed solution was taken, and then 600 μL of deuterated DMSO was added, and the yield was measured by a nuclear magnetic resonance spectrometer. The results showed that the yield of bisphenol A was 99%, and the yield of benzimidazolone was 59%.

[0038] Example 1

[0039] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with a CR purity (1 mmol), 2 mmol of o-phenylenediamine, and 0.2 mmol of ionic liquid catalyst were added. After placing the pressure-resistant tube reactor, stirring and heating were started. The reaction system was heated to 130 °C and reacted at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to room temperature, and the resulting mixed solution was the product. Further, bisphenol A and benzimidazolone could be separated by a post-treatment method including column chromatography. 2 mL of dimethyl sulfoxide was added to the mixed solution, mixed evenly, 50 μL was taken, and then 600 μL of deuterated DMSO was added, and the yield was measured by a nuclear magnetic resonance spectrometer. The results showed that the yield of bisphenol A was 99%, and the yield of benzimidazolone was 95%.

[0040] The specific reaction route diagram is as Figure 1 shown. The nuclear magnetic resonance hydrogen spectrum diagram of the product bisphenol A is as Figure 2 shown. The nuclear magnetic resonance hydrogen spectrum diagram of the product benzimidazolone is as Figure 3 shown, indicating the successful progress of the method of the present invention.

[0041] Example 2

[0042] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with CR purity (1 mmol), 2 mmol of o-phenylenediamine, 0.4 mmol of ionic liquid catalyst, and different masses of water (0.05 g, 0.02 g, 0.01 g) were added respectively. After placing the pressure-resistant tube reactor properly, stirring and heating were started. The reaction system was heated to 130 °C and reacted at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to room temperature, and the resulting mixed solution was the product. 2 mL of dimethyl sulfoxide was added to the mixed solution, and after mixing evenly, 50 μL was taken, and then 600 μL of deuterated DMSO was added. The yield was determined by a nuclear magnetic resonance spectrometer. The results showed that the yields of bisphenol A were 99%, 99%, 99% respectively, and the yields of benzimidazolone were 99%, 90%, 91% respectively.

[0043] Example 3

[0044] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with CR purity (1 mmol), 2 mmol of o-phenylenediamine, and different molar amounts of ionic liquid catalyst (0.06 mmol, 0.12 mmol, 0.20 mmol, 0.30 mmol, 0.40 mmol, 0.50 mmol) were added. After placing the pressure-resistant tube reactor properly, stirring and heating were started. The reaction system was heated to 130 °C and reacted at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to room temperature, and the resulting mixed solution was the product. 2 mL of dimethyl sulfoxide was added to the mixed solution, and after mixing evenly, 50 μL was taken, and then 600 μL of deuterated DMSO was added. The yield was determined by a nuclear magnetic resonance spectrometer. The results showed that the yields of bisphenol A were 56%, 70%, 99%, 99%, 99%, 99% respectively, and the yields of benzimidazolone were 55%, 70%, 95%, 95%, 95%, 99% respectively.

[0045] Example 4

[0046] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with a CR purity (1 mmol), 2 mmol of o-phenylenediamine, and 0.2 mmol of an ionic liquid catalyst were added. After placing the pressure-resistant tube reactor, stirring and heating were started. The reaction system was heated to 130 °C and reacted at this temperature for 0.5, 1, 2, 2.5, 3, 4, 5, and 6 hours, respectively. After the reaction was completed, the temperature was lowered to room temperature, and the resulting mixed solution was the product. 2 mL of dimethyl sulfoxide was added to the mixed solution and mixed evenly. 50 μL was taken and then 600 μL of deuterated DMSO was added, and the yield was measured by a nuclear magnetic resonance spectrometer. The results showed that the yields of bisphenol A were 89%, 91%, 93%, 99%, 99%, 99%, 99%, and 99%, respectively, and the yields of benzimidazolone were 75%, 77%, 78%, 85%, 85%, 95%, 94%, and 94%, respectively.

[0047] Example 5

[0048] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with a CR purity (1 mmol), different molar amounts of o-phenylenediamine (1 mmol, 1.5 mmol, 2 mmol, 3 mmol), and 0.2 mmol of an ionic liquid catalyst were added. After placing the pressure-resistant tube reactor, stirring and heating were started. The reaction system was heated to 130 °C and reacted at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to room temperature, and the resulting mixed solution was the product. 50 μL of the resulting mixed solution was taken and then 600 μL of deuterated DMSO was added, and the yield was measured by a nuclear magnetic resonance spectrometer. The results showed that the yields of bisphenol A were 72%, 99%, 99%, and 99%, respectively, and the yields of benzimidazolone were 65%, 92%, 95%, and 96%, respectively.

[0049] Example 6

[0050] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, add 0.254 g of different polycarbonate wastes (sunshine board, PC lamp tube, transparent board, CD, waterproof junction box, water bucket) (about 1 mmol), 2 mmol of o-phenylenediamine, and 0.2 mmol of ionic liquid catalyst. After placing the pressure-resistant tube reactor properly, start stirring and heating. The reaction system is heated to 130 °C and reacted at this temperature for 4 hours. After the reaction is completed, cool down to room temperature, and the resulting mixed solution is the product. Add 2 mL of dimethyl sulfoxide to the mixed solution, mix well, take 50 µL, and then add 600 µL of deuterated DMSO. The yield is determined by a nuclear magnetic resonance spectrometer. The results show that the yields of bisphenol A are 98%, 99%, 93%, 99%, 98%, and 99% respectively, and the yields of benzimidazolone are 77%, 85%, 71%, 97%, 87%, and 99% respectively.

[0051] Example 7

[0052] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, add 0.254 g of polycarbonate powder with CR purity (1 mmol), 2 mmol of different o-phenylenediamine compounds ( ;; ; ; ), and 0.2 mmol of ionic liquid catalyst. After placing the pressure-resistant tube reactor properly, start stirring and heating. The reaction system is heated to 130 °C and reacted at this temperature for 4 hours. After the reaction is completed, cool down to room temperature, and the resulting mixed solution is the product. Add 2 mL of dimethyl sulfoxide to the mixed solution, mix well, take 50 µL, and then add 600 µL of deuterated DMSO. The yield is determined by a nuclear magnetic resonance spectrometer. The results show that the yields of bisphenol A are 99%, 99%, 99%, and 99% respectively, and the yields of benzimidazolone are 96%, 90%, 91%, and 92% respectively.

[0053] Example 8

[0054] In a pressure-resistant tube reactor equipped with an electromagnetic stirrer, a thermocouple, and a programmable temperature controller, 0.254 g of polycarbonate powder with CR purity (1 mmol), 2 mmol of o-phenylenediamine, and 0.2 mmol of ionic liquid catalyst were added. After placing the pressure-resistant tube reactor, stirring and heating were started. The reaction system was heated to 110 °C, 120 °C, 130 °C, 140 °C, and 150 °C respectively, and reacted at this temperature for 4 hours. After the reaction was completed, the temperature was lowered to room temperature, and the obtained mixed solution was the product. 2 mL of dimethyl sulfoxide was added to the mixed solution and mixed evenly. 50 μL of the mixed solution was taken, and then 600 μL of deuterated DMSO was added. The yield was measured by a nuclear magnetic resonance spectrometer. The results showed that the yields of bisphenol A were 95%, 96%, 99%, 89%, and 77% respectively, and the yields of benzimidazolone were 83%, 83%, 95%, 74%, and 68% respectively.

[0055] The above-described embodiments have described the technical solutions of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, supplements, or substitutions in a similar manner within the scope of the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for high-value recycling of polycarbonate waste, characterized in that: The following steps are involved: A reaction system is constructed by using crushed bisphenol A type polycarbonate waste, o-phenylenediamine compounds and ionic liquid catalysts, and the reaction system is placed at a temperature of 110 to 130° C. in an air atmosphere for 0.5 to 6 hours to obtain bisphenol A and benzimidazolone compounds; The molar ratio of bisphenol A type polycarbonate waste to o-phenylenediamine compounds is 1:1-3, and the molar ratio of bisphenol A type polycarbonate waste to ionic liquid catalyst is 1:0.20-0.50; The structural formula of the o-phenylenediamine compound is as follows; wherein R1 and R2 are each independently selected from hydrogen, methyl, methoxy or halogen; ； The structural formula of the ionic liquid catalyst is: 。 2. The high-value recycling method for polycarbonate waste according to claim 1, characterized in that: Bisphenol A polycarbonate waste includes plates, sheets, tubes or films.

3. The high-value recycling method for polycarbonate waste according to claim 1, characterized in that: The o-phenylenediamine compound is at least one of the following compounds: 。 4. The high-value recycling method for polycarbonate waste according to claim 3, characterized in that: The benzimidazolone compound is at least one of the following compounds: 。 5. The high-value recycling method for polycarbonate waste according to claim 1, characterized in that: The yield of bisphenol A is ≥56%, and the yield of benzimidazolone compounds is ≥65%.

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