A method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compound

Abstract

The invention discloses a method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compounds, belonging to the technical field of depolymerization and recovery of polymer materials. The method comprises: constructing a reaction system comprising bisphenol A polycarbonate, epoxy compounds, Lewis acids, bases and ionic liquids, placing the reaction system at a temperature of 70 to 150 DEG C for a reaction of ≥10 min under an air atmosphere, so as to obtain bisphenol A and cyclic carbonate; wherein the epoxy compounds comprise at least one of styrene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 1,2-epoxydodecane, n-butyl glycidyl ether, glycidyl phenyl ether, 2-toluene glycidyl ether and 3-(1-naphthyloxy)-1,2-propylene oxide; the base is an inorganic base or an organic base; the method has mild reaction conditions, high resource utilization efficiency, good operation safety and high chemical monomer yield, and has broad application prospects in the field of waste plastic treatment.

Description

Technical Field

[0001] The invention relates to the technical field of depolymerization and recovery of polymer materials, and in particular to a method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compounds. Background Art

[0002] From daily necessities to large industrial products, plastics are almost everywhere, bringing great convenience to modern life. With the increase in the use of plastic products, the issue of plastic product recycling has attracted widespread attention. Traditional plastic recycling technologies (such as landfill, incineration and mechanical recycling) cannot achieve effective and full utilization of carbon resources, and may also cause certain harm to the environment and human health. In contrast, plastic chemical recycling technology has higher resource utilization and environmental friendliness. In particular, some methods of solvent hydrolysis of waste plastics can realize the value-added transformation of waste plastics into basic chemical raw materials or other high value-added chemicals.

[0003] Polycarbonate can be divided into aliphatic polycarbonate and aromatic polycarbonate according to its structure. Currently, the industrial application is limited to bisphenol A polycarbonate, which has the advantages of good mechanical properties, optical properties, thermal properties and chemical resistance, and is mainly used in the fields of electronics, plates, films and automotive parts. Bisphenol A is an important structural unit in the industrial production of polycarbonate, and its purity is required to be high. The chemical solvent decomposition of waste polycarbonate plastics to centrally recycle bisphenol A (BPA) can not only reduce the demand for newly synthesized BPA, thereby reducing the consumption of fossil fuels, but also reduce the exposure of bisphenol A in waste polycarbonate plastics to the environment, leading to the continuous accumulation of its toxicity. At present, the main methods for regenerating BPA by polycarbonate solvent decomposition are alcoholysis, aminolysis and hydrolysis (such as Chinese patent documents with publication numbers CN118164826A, CN111484395A, CN108607604A, etc.). Among them, alcoholysis and aminolysis can achieve efficient regeneration of BPA while converting carbonate bonds into high value-added chemicals. The hydrolysis of polycarbonate (PC) uses water as a depolymerizing agent, which is more environmentally friendly than organic solvents such as alcohol and ammonia. However, hydrolysis faces the problem of greenhouse gas generation and harsh reaction conditions, which is the main reason restricting its widespread application, and this problem has not yet been effectively solved.

[0004] Cyclic carbonates are an important class of organic compounds, including propylene carbonate and ethylene carbonate. As multifunctional chemicals, they have broad application prospects in the production of lithium battery electrolytes, organic solvents, polymers and biomedicine. There are many methods for preparing cyclic carbonates, including transesterification, phosgene, urea alcoholysis, ethylene oxide and carbon dioxide addition, etc. For example, Chinese patent document No. CN112939924A discloses that cyclic carbonates are obtained by contacting alkylene oxide and carbon dioxide with a complex catalyst, wherein the chemical formula of the complex catalyst is as follows: (ZnX) · [Fe(CN)4·mL] · (ZnX2) n , L is a diamine ligand coordinated with metal Fe; Chinese patent document with publication number CN113996339A discloses a catalyst for preparing cyclic carbonate and a method for preparing cyclic carbonate, the invention uses epoxide and carbon dioxide to synthesize cyclic carbonate under a saccharin salt organic catalyst system, wherein the saccharin salt organic catalyst is prepared from saccharin and triethylenediamine. However, in the above method, the catalyst cannot be directly purchased, and the reaction conditions are also relatively harsh.

[0005] In the prior art, there is no report on the simultaneous upgrading of waste plastics into bisphenol A and cyclic carbonates, and as mentioned above, the current method conditions for synthesizing cyclic carbonates are relatively harsh. Therefore, it is necessary to study the method for upgrading waste polycarbonate into bisphenol A and cyclic carbonates. Summary of the invention

[0006] The invention provides a method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compound. The method has mild reaction conditions, readily available raw materials, high resource utilization efficiency, and good operation safety. Two chemical monomers, bisphenol A and cyclic carbonate, can be prepared simultaneously with high yield. The method of the invention has broad application prospects in the field of waste plastic treatment.

[0007] The specific technical solutions adopted are as follows:

[0008] A method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compound comprises the following steps:

[0009] A reaction system including bisphenol A polycarbonate, an epoxy compound, a Lewis acid, a base and an ionic liquid is constructed, and the reaction system is placed at a temperature of 70 to 150° C. for a reaction period of ≥10 min under an air atmosphere to obtain bisphenol A and a cyclic carbonate;

[0010] The epoxy compound includes at least one of styrene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 1,2-epoxydodecane, n-butyl glycidyl ether, glycidyl phenyl ether, 2-toluene glycidyl ether, and 3-(1-naphthyloxy)-1,2-propylene oxide;

[0011] The base is an inorganic base or an organic base;

[0012] The ionic liquid includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium acetate, and 1-butyl-3-methylimidazolium bromide.

[0013] The present invention constructs a reaction system including bisphenol A polycarbonate, an epoxy compound, a Lewis acid, a base and an ionic liquid. In the reaction system, the bisphenol A polycarbonate can be depolymerized to generate bisphenol A and carbon dioxide, and the carbon dioxide and the epoxy compound further undergo a cycloaddition reaction to generate cyclic carbonates such as styrene carbonate. On the one hand, the present invention realizes high-value recovery of the bisphenol A polycarbonate and fully utilizes the carbon resources therein. On the other hand, the cycloaddition reaction of carbon dioxide and the epoxy compound further drives the forward depolymerization of the bisphenol A polycarbonate, which is beneficial to the high-yield preparation of bisphenol A and cyclic carbonates.

[0014] Preferably, the Lewis acid is selected from at least one of zinc bromide, zinc chloride, zinc iodide, magnesium chloride, aluminum chloride, and ferric chloride; the Lewis acid can form a coordination bond with the oxygen atom in the epoxy compound to make the carbon atom in the epoxy compound more susceptible to attack by nucleophilic reagents.

[0015] Optionally, the inorganic base is selected from at least one of potassium carbonate, sodium carbonate, sodium hydroxide, and potassium hydroxide, and the organic base is selected from at least one of triethylamine and 1,8-diazabicyclo[5.4.0]undec-7-ene; during the conversion of polycarbonate PC, the imidazole salt ionic liquid is deprotonated under the action of the base to obtain nitrogen heterocyclic carbene, which plays an important role in the capture and conversion of carbon dioxide.

[0016] Preferably, the molar ratio of the bisphenol A polycarbonate to the epoxy compound is 1:0.5-3, and more preferably 1:1.5-2; under the above raw material ratio, it is beneficial to promote the full depolymerization of bisphenol A polycarbonate, avoid unnecessary increase in raw material costs, and take into account both reaction efficiency and economy.

[0017] Preferably, based on the molar number of bisphenol A polycarbonate as 100%, the amount (molar number) of the Lewis acid added is 1-10%, and the amount (molar number) of the base added is 1-10%; further preferably, the amount (molar number) of the Lewis acid added is 5-10%, and the amount (molar number) of the base added is 5-10%. The present invention limits the feeding amount of the Lewis acid and the base, which can effectively promote the reaction of the present invention and ensure the purity and selectivity of the product.

[0018] Preferably, the molar ratio of the bisphenol A polycarbonate to the ionic liquid is 1:1-3, and more preferably 1:2. The ionic liquid can interact with the carbonyl oxygen of the polycarbonate PC through electrostatic interaction, making the carbonyl carbon more susceptible to OH - It can also act as a strong nucleophile to attack the carbon atom in the epoxy compound to promote the ring opening of the epoxy compound, which is the rate-controlling step of the cycloaddition reaction.

[0019] Preferably, in order to take into account both reaction efficiency and product yield, the reaction system is placed at 70 to 150° C. under air atmosphere to carry out the reaction for 20 min to 8 h.

[0020] The invention also provides the application of the method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compound in the treatment of waste plastics.

[0021] Specifically, the waste plastic is waste made of bisphenol A polycarbonate, including waste CDs, waste buckets, waste films, waste bottles, waste plates, waste sheets, waste lamps, etc. The method of the present invention is applicable to various forms of bisphenol A polycarbonate waste samples, and the recovery rates of bisphenol A and cyclic carbonate can reach 99%, showing excellent efficiency and adaptability.

[0022] When upgrading and converting waste plastics, they need to be crushed into centimeter-sized flakes, particles or powders in advance to ensure their resource utilization effect, so as to obtain bisphenol A and cyclic carbonates in a targeted manner with high yield.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The method of the present invention has a simple process flow, high economic benefits, mild reaction conditions, and does not require an inert gas atmosphere or additional pressure. Cyclic carbonates such as bisphenol A and styrene carbonate can be prepared in high yield by reacting at a temperature of 70 to 150° C. for 1 to 5 hours, thereby achieving high-value recovery of waste polyester plastics.

[0025] (2) The substrate applicability of the method of the present invention is wide, not limited to styrene oxide, but also applicable to the upgrading of various epoxy compounds including 1,2-propylene oxide, 1,2-butylene oxide, 1,2-epoxydodecane, n-butyl glycidyl ether, glycidyl phenyl ether, 2-toluene glycidyl ether, and 3-(1-naphthyloxy)-1,2-propylene oxide. It has higher environmental friendliness, resource utilization efficiency and operational safety, and has high application value.

[0026] (3) The method of the present invention can achieve dual upgrading and conversion of bisphenol A polycarbonate, and can simultaneously obtain the reaction products bisphenol A and cyclic carbonate, and bisphenol A and cyclic carbonate are easy to separate. These two reaction products can be further used to synthesize functional chemicals as high-value-added chemical monomers; and compared with other methods for synthesizing cyclic carbonates, the reaction conditions of the present invention are simpler and milder, and the catalyst is easy to obtain. DETAILED DESCRIPTION

[0027] The present invention will be further illustrated below in conjunction with the examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples that do not specify specific conditions are usually performed under normal conditions or according to the conditions recommended by the manufacturer. The content that is not described in detail in this specification sheet belongs to the prior art known to professionals in the field. The experimental materials used in the following examples, if not otherwise specified, can be purchased by conventional biochemical reagent companies.

[0028] The reaction processes of the following examples and comparative examples were all carried out under normal pressure without applying additional pressure, and the polycarbonate PC powders used were all bisphenol A polycarbonate.

[0029] Example 1

[0030] 0.254 g CR purity PC powder (1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.0113 g zinc bromide (0.05 mmol), 0.0069 g potassium carbonate (0.05 mmol) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) were added to a glass tube, and the glass tube was placed on a heat-collecting constant temperature heating magnetic stirrer, stirring and heating were turned on, and the reaction system was heated to 100 ° C and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yield of bisphenol A in this example was 99.6%, and the yield of styrene carbonate was 99.0%.

[0031] The reaction route equation of the present invention is shown below:

[0032] ;

[0033] Specifically, the method for separating bisphenol A and styrene carbonate is as follows: after the reaction is completed, ethyl acetate and water are added to the reaction mixture for extraction, the organic phase is collected, and the organic phase is dried by a rotary evaporator. The product is separated by column chromatography, and the eluent is a mixture of ethyl acetate and petroleum ether.

[0034] Example 2

[0035] 0.254 g CR purity PC powder (1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.0113 g zinc bromide (0.05 mmol), 0.0069 g potassium carbonate (0.05 mmol) and 2 mmol of different ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium acetate) were added to different glass tubes respectively, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this example were 6.0%, 82.5%, 72.7%, 65.9% and 57.3%, respectively, and the yields of styrene carbonate were 14.0%, 50.0%, 69.0%, 63.6% and 47.8%, respectively.

[0036] Example 3

[0037] 0.254 g CR purity PC powder (1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.05 mmol of different Lewis acids (zinc chloride, zinc iodide, magnesium chloride, aluminum chloride, ferric chloride), 0.0069 g potassium carbonate (0.05 mmol) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes respectively. The glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this embodiment were 87.7%, 83.8%, 76.6%, 71.2% and 46.8%, respectively, and the yields of styrene carbonate were 75.5%, 72.7%, 53.1%, 57.0% and 56.5%, respectively.

[0038] Example 4

[0039] 0.254 g CR purity PC powder (1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.0113 g zinc bromide (0.05 mmol), 0.05 mmol of different bases (sodium carbonate, sodium hydroxide, potassium hydroxide, triethylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes respectively, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this embodiment were 96.8%, 84.6%, 84.0%, 79.7% and 95.8%, respectively, and the yields of styrene carbonate were 89.0%, 60.5%, 60.4%, 52.7% and 55.4%, respectively.

[0040] Example 5

[0041] Add CR purity PC powder (1 mmol), different moles of styrene oxide (the molar ratio of PC powder to styrene oxide is 2:1, 1.5:1, 1:1, 1:2, respectively), 0.0113 g zinc bromide (0.05 mmol), 0.0069 g potassium carbonate (0.05 mmol) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) to different glass tubes, place the glass tube on a heat-collecting constant temperature heating magnetic stirrer, start stirring and heating. The reaction system was heated to 100 ° C and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yields were determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this example were 32.2%, 46.0%, 72.1% and 99.3%, respectively, and the yields of styrene carbonate were 26.8%, 33.3%, 64.2% and 99.0%, respectively.

[0042] Example 6

[0043] 0.254 g of CR-purity PC powder (1 mmol), 0.1802 g of styrene oxide (1.5 mmol), different moles of zinc bromide (0.01 mmol, 0.03 mmol, 0.07 mmol, 0.10 mmol), corresponding different moles of potassium carbonate (0.01 mmol, 0.03 mmol, 0.07 mmol, 0.10 mmol) and 0.4382 g of 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yields were determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this embodiment were 69.5%, 72.9%, 99.8% and 99.8%, respectively, and the yields of styrene carbonate were 54.0%, 60.9%, 99.7% and 99.8%, respectively.

[0044] Example 7

[0045] 0.254 g CR purity PC powder (1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.0113 g zinc bromide (0.05 mmol), 0.0069 g potassium carbonate (0.05 mmol) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 70, 90, 110, 130, and 150 ° C, respectively, and reacted at this temperature for 4 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this example were 72.2%, 91.4%, 99.8%, 99.7% and 99.6%, respectively, and the yields of styrene carbonate were 71.6%, 90.1%, 99.7%, 99.7% and 99.6%, respectively.

[0046] Example 8

[0047] 0.254 g centimeter-scale PC waste crushed materials (buckets, CDs, waterproof wiring trays, transparent plates; all made of bisphenol A polycarbonate) (about 1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.0113 g zinc bromide (0.05 mmol), 0.0069 g potassium carbonate (0.05 mmol) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 5 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yields were determined by H NMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this example were 97.0%, 95.3%, 91.1%, and 94.2%, respectively, and the yields of styrene carbonate were 99.9%, 96.0%, 96.0%, and 99.6%, respectively.

[0048] Example 9

[0049] 0.254 g of CR-pure PC powder (1 mmol), different epoxy compounds (1,2-propylene oxide, 1,2-butylene oxide) (1.5 mmol), 0.0113 g of zinc bromide (0.05 mmol), 0.0069 g of potassium carbonate (0.05 mmol) and 0.4382 g of 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 2 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR, with trioxane as the internal standard. The results showed that the yields of bisphenol A in this embodiment were 99.4% and 99.1%, respectively, and the yields of cyclic carbonate were 97.9% and 98.7%, respectively. The corresponding structural formula of cyclic carbonate is shown below:

[0050] .

[0051] Example 10

[0052] 0.254 g of CR-purity PC powder (1 mmol), different epoxy compounds (1,2-epoxydodecane, n-butyl glycidyl ether, glycidyl phenyl ether, 2-toluene glycidyl ether, 3-(1-naphthyloxy)-1,2-epoxypropane) (1.5 mmol), 0.0225 g of zinc bromide (0.10 mmol), 0.0138 g of potassium carbonate (0.10 mmol) and 0.4382 g of 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, and stirring and heating were turned on. The reaction system was heated to 100 ° C and reacted at this temperature for 8 h. After the reaction was completed, the temperature was cooled to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by H NMR, with trioxane as the internal standard. The results showed that the yields of bisphenol A in this embodiment were 98.3%, 97.7%, 99.9%, 95.3%, and 96.5%, respectively, and the yields of cyclic carbonate were 99.5%, 91.3%, 90.8%, 94.3%, and 76.1%, respectively. The corresponding structural formula of cyclic carbonate is shown below:

[0053] .

[0054] Embodiment 11

[0055] 0.254 g CR purity PC powder (1 mmol), 0.1802 g styrene oxide (1.5 mmol), 0.0113 g zinc bromide (0.05 mmol), 0.0069 g potassium carbonate (0.05 mmol) and 0.4382 g 1-butyl-3-methylimidazolium bromide (2 mmol) were added to different glass tubes, and the glass tubes were placed on a heat-collecting constant temperature heating magnetic stirrer, stirring and heating were turned on, and the reaction system was heated to 100 ° C, and reacted at this temperature for 10 min, 20 min, 30 min, 60 min, 120 min, 180 min, and 300 min, respectively. After the reaction was completed, the temperature was lowered to room temperature to obtain a mixed solution, and the obtained mixed solution was passed through 1 The yield was determined by HNMR with trioxane as the internal standard. The results showed that the yields of bisphenol A in this example were 65.3%, 80.6%, 92.0%, 92.3%, 93.2%, 99.0% and 99.9%, respectively, and the yields of styrene carbonate were 74.5%, 81.8%, 89.3%, 95.3%, 98.1%, 99.0% and 99.9%, respectively.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that the ionic liquid 1-butyl-3-methylimidazolium bromide is not added, and the other reaction conditions and parameters are the same. After the reaction is completed, a mixed solution is obtained, and the obtained mixed solution is passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yield of bisphenol A in this comparative example was 0%, and the yield of styrene carbonate was 0%.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that Lewis acid zinc bromide is not added, and the other reaction conditions and parameters are the same. After the reaction is completed, a mixed solution is obtained, and the obtained mixed solution is passed through 1 The yield was determined by H NMR with trioxane as the internal standard. The results showed that the yield of bisphenol A in this comparative example was 74.7%, and the yield of styrene carbonate was 66.2%.

[0060] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compound, characterized in that: The following steps are involved: A reaction system comprising bisphenol A polycarbonate, an epoxy compound, a Lewis acid, a base and an ionic liquid is constructed, and the reaction system is placed at a temperature of 70 to 150° C. in an air atmosphere for 1 to 5 hours to obtain bisphenol A and a cyclic carbonate; the molar ratio of the bisphenol A polycarbonate to the epoxy compound is 1:0.5 to 3; the molar ratio of the bisphenol A polycarbonate to the ionic liquid is 1:1 to 3; The epoxy compound is at least one of styrene oxide, glycidyl phenyl ether, 2-toluene glycidyl ether, and 3-(1-naphthyloxy)-1,2-epoxypropane; The base is an inorganic base or an organic base; The ionic liquid is at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium acetate, and 1-butyl-3-methylimidazolium bromide.

2. The method for recovering bisphenol A and cyclic carbonate from polycarbonate coupled epoxy compounds according to claim 1, characterized in that: The Lewis acid is selected from at least one of zinc bromide, zinc chloride, zinc iodide, magnesium chloride, aluminum chloride and ferric chloride.

3. The method for recovering bisphenol A and cyclic carbonate from polycarbonate coupled epoxy compounds according to claim 1, characterized in that: The inorganic base is selected from at least one of potassium carbonate, sodium carbonate, sodium hydroxide and potassium hydroxide; the organic base is selected from at least one of triethylamine and 1,8-diazabicyclo[5.4.0]undec-7-ene.

4. The method for recovering bisphenol A and cyclic carbonate from polycarbonate coupled epoxy compounds according to claim 1, characterized in that: Based on 100% of the molar number of bisphenol A polycarbonate, the molar amount of the Lewis acid added is 1-10%, and the molar amount of the base added is 1-10%.

5. The method for recovering bisphenol A and cyclic carbonate from polycarbonate coupled epoxy compounds according to claim 1, characterized in that: The reaction time is 20 min to 8 h.

6. Use of the method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compounds according to any one of claims 1 to 5 in the treatment of waste plastics.

7. Application of the method for recovering bisphenol A and cyclic carbonate by coupling polycarbonate with epoxy compound according to claim 6 in waste plastic treatment, characterized in that: Waste plastics are waste materials made of bisphenol A polycarbonate. When upgrading and converting, waste plastics need to be broken into centimeter-sized flakes, granules or powders in advance.