Degradation and recovery method of polyester material
By using copper chromite or chromium trioxide catalysts and methanol ball milling, the problem of high-temperature and high-energy-consumption degradation of aromatic polyester materials was solved, achieving efficient and low-energy degradation of polyester materials into dimethyl terephthalate.
Patent Information
- Application Number
- CN202511497008.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-20
- Publication Date
- 2025-12-12
AI Technical Summary
In existing technologies, the degradation process of aromatic polyester materials requires the participation of high-temperature catalysts and consumes a lot of energy, making it difficult to achieve efficient degradation.
Copper chromite or chromium trioxide was used as a catalyst, methanol was used as a hydrogen donor, and the mixture was mixed with polyester material and then ball-milled. The molecular chains were activated by mechanical force and degradation was promoted under mild conditions. Dimethyl terephthalate was then obtained by solid-liquid separation and purification.
It has achieved efficient degradation of polyester materials into dimethyl terephthalate under mild conditions. The degradation process is simple, energy-efficient, and yields over 88%.
Smart Images
Figure CN121107977A_ABST
Abstract
Description
TECHNICAL FIELD
[0002] The application belongs to the technical field of plastic waste treatment, and particularly relates to a degradation and recovery method of polyester materials. BACKGROUND
[0003] Plastics have brought countless conveniences to human's clothing, food, shelter and living, but due to their stable structure, they are difficult to be decomposed in the natural environment, thereby causing serious damage to the ecological environment. Therefore, developing an efficient high-value conversion method of waste plastics can not only effectively solve the problem of environmental pollution, but also reduce energy consumption and turn waste into treasure.
[0004] Polyesters are an important class of plastics, among which polyethylene terephthalate (PET) is the most common and is widely used in beverage bottles, food packaging films, fibers, electronic appliances and building materials, etc. Different types of polyester materials differ in degradability, with aliphatic being more easily degradable and aromatic polyester being relatively difficult to degrade. At present, alcoholysis reaction system is mainly used for degrading aromatic polyester materials, but the alcoholysis reaction process not only needs the participation of a catalyst, but also needs high temperature conditions of 200-300℃, and the degradation process consumes a large amount of energy. SUMMARY
[0005] Therefore, the application provides a degradation and recovery method of polyester materials, which is simple and easy to operate, has low energy consumption, and can efficiently degrade polyester materials into dimethyl terephthalate.
[0006] To solve the above technical problems, the application provides a degradation and recovery method of polyester materials, which comprises the following steps: The polyester material, the catalyst and the hydrogen donor are mixed and subjected to ball milling to obtain dimethyl terephthalate. The catalyst comprises copper chromite or chromium trioxide, and the hydrogen donor is methanol.
[0007] Preferably, the mass ratio of the polyester material to the hydrogen donor is 1:2-10.
[0008] Preferably, the mass ratio of the polyester material to the catalyst is 0.5-2:0.1-2.
[0009] Preferably, the polyester material comprises polyethylene terephthalate and / or polybutylene terephthalate. The average particle size of the polyester material is 50-150 μm.
[0010] Preferably, the rotation speed of the ball milling is 200-800 rpm, the ball milling time is 6-24 h, the ball milling temperature is room temperature, and the room temperature is 20-35℃.
[0011] Preferably, the material of the grinding ball and the ball mill tank in the ball milling process comprises agate, stainless steel or zirconium oxide, respectively.
[0012] Preferably, the mass ratio of the grinding ball and the polyester material in the ball milling process is 50-150:1-2.
[0013] Preferably, the ball milling process further comprises: after the ball milling process, mixing the ball-milling system with a solvent to perform solid-liquid separation, to obtain a solid phase and a liquid phase, respectively; and purifying the liquid phase to obtain the dimethyl terephthalate.
[0014] Preferably, the solid phase comprises a catalyst, and the solvent comprises ethanol and / or dichloromethane.
[0015] Preferably, the purification method comprises silica gel column chromatography or recrystallization.
[0016] The present application provides a degradation and recycling method of a polyester material, comprising the following steps: mixing a polyester material, a catalyst and a hydrogen donor to perform ball milling, to obtain dimethyl terephthalate; the catalyst comprises copper chromite or chromium trioxide; and the hydrogen donor is methanol. In the present application, copper chromite or chromium trioxide is used as a catalyst, and methanol is used as a hydrogen donor. Under the mechanical force of ball milling, the molecular chain can be activated, the molecular chain can be broken, and the reactants can be mixed strongly. The good catalytic performance of the catalyst can reduce the activation energy of the reaction, so as to promote the efficient degradation of the polyester material under mild conditions. The degradation and recycling method provided by the present application does not need additional heating, and has the advantages of simple process, low energy consumption, high selectivity of the polyester material to be degraded into dimethyl terephthalate, high efficiency and economy. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 The actual picture of the dimethyl terephthalate obtained by degradation in Example 1; Figure 2 The 1H NMR spectrum of the dimethyl terephthalate obtained by degradation in Example 1. DETAILED DESCRIPTION
[0018] The present application provides a degradation and recycling method of a polyester material, comprising the following steps: Mixing a polyester material, a catalyst and a hydrogen donor to perform ball milling, to obtain dimethyl terephthalate (DMT).
[0019] The catalyst comprises copper chromite (2CuO·Cr2O3) or chromium trioxide (Cr2O3), and the hydrogen donor is methanol.
[0020] As a specific embodiment of the present application, the polyester material can comprise polyethylene terephthalate (PET) and / or polybutylene terephthalate (PBT), and can specifically be polyethylene terephthalate or polybutylene terephthalate; the polyester material can be in the form of a powder, and the average particle size of the polyester material can be 50-150 μm, and can specifically be 50 μm, 150 μm or 500 μm.
[0021] In the present application, the catalyst comprises copper chromite (2CuO·Cr2O3) or chromium trioxide (Cr2O3); the mass ratio of the polyester material to the catalyst can be 0.5-2:0.1-2, and can also be 1:0.8-2, and can specifically be 1:0.8, 1:1 or 1:1.5.
[0022] In the present application, the hydrogen donor is methanol; the mass ratio of the polyester material to the hydrogen donor can be 1:2-10, and can specifically be 1:4, 1:6, 1:8 or 1:9.
[0023] As a specific embodiment of the present application, the mixing can comprise the following steps: first mixing the polyester material and the catalyst to obtain a first mixture; second mixing the first mixture and the hydrogen donor. The present application does not have any special limitation on the manner of the first mixing and the second mixing, and any conventional manner in the art can be used.
[0024] As a specific embodiment of the present application, the rotation speed of the ball mill can be 200-800 rpm, and can specifically be 200 rpm, 400 rpm, 600 rpm or 800 rpm; the ball milling time can be 6-24 h, and can specifically be 6 h, 12 h, 18 h or 24 h; the material of the grinding balls used in the ball mill can comprise agate, stainless steel or zirconium oxide; the mass ratio of the grinding balls to the polyester material can be 50-150:1-2, and can specifically be 90:1, 100:1, 110:1, 130:1 or 150:1; the material of the ball mill jar used in the ball mill can comprise agate, stainless steel or zirconium oxide, and the material of the ball mill jar can be the same as that of the grinding balls.
[0025] As a specific embodiment of the present application, the temperature of the ball mill can be room temperature, and the room temperature can be 20-35℃, and can also be 25-30℃; the ball milling can be carried out in an air atmosphere.
[0026] In the present application, when the polyester material is polyethylene terephthalate, the equation of the degradation reaction is shown in formula a; when the polyester material is polybutylene terephthalate, the equation of the degradation reaction is shown in formula b: Formula a; Formula b.
[0027] In the present application, the ball milling can grind the polyester material, and under the mechanical force of the ball milling, the polyester molecular chain can be activated and broken, and the reactants can be strongly mixed, the good catalytic performance of the catalyst can reduce the activation energy of the reaction, thereby promoting the efficient degradation of the polyester material under mild conditions.
[0028] As a specific embodiment of the present application, the ball-milled system can be mixed with a solvent after ball milling, and then solid-liquid separation is performed to obtain a solid phase and a liquid phase; the liquid phase is purified to obtain the dimethyl terephthalate.
[0029] As a specific embodiment of the present application, the mixing of the ball-milled system and the solvent can be performed by flushing the ball-milled system with the solvent to collect a mixed liquid; the solvent can include ethanol and / or dichloromethane, and can specifically be ethanol or dichloromethane.
[0030] As a specific embodiment of the present application, the solid-liquid separation can be filtration; the present application does not have special requirements for the filtration, and a conventional method in the art can be used.
[0031] As a specific embodiment of the present application, the solid phase can include a catalyst. In the present application, the solid phase obtained after drying can be dried to obtain a recovered catalyst; the drying can be vacuum drying, the temperature of the vacuum drying can be 30-40℃, and can specifically be 35℃; the time of the vacuum drying can be 10-14h, and can specifically be 12h. The present application does not have special requirements for the vacuum degree of the vacuum drying, as long as it is a vacuum condition.
[0032] As a specific embodiment of the present application, the purification method can include silica gel column chromatography or recrystallization; the particle size of the silica gel in the silica gel column used in the silica gel column chromatography can be 200-300 mesh; the mobile phase in the silica gel column chromatography can be dichloromethane. As a specific embodiment of the present application, the solvent used in the recrystallization can be ethanol.
[0033] As a specific embodiment of the present application, the purification can further include drying the solid obtained by the purification to obtain the dimethyl terephthalate; the drying can be vacuum drying, the temperature of the vacuum drying can be 30-40℃, and can specifically be 35℃; the time of the vacuum drying can be 10-14h, and can specifically be 12h. The present application does not have special requirements for the vacuum degree of the vacuum drying, as long as it is a vacuum condition.
[0034] In the present application, the dimethyl terephthalate obtained by degradation is a white crystal.
[0035] The polyester material degradation and recovery method provided by the application realizes direct conversion of polyester material to dimethyl terephthalate by one-step method, and the degradation and recovery method is mild, green and efficient; the degradation method provided by the application has a dimethyl terephthalate yield of more than 88%.
[0036] In order to further illustrate the application, the technical solutions provided by the application are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the application.
[0037] Example 1 PET powder with an average particle size of 50 μm and a catalyst copper chromite were mixed according to a mass ratio of 1:0.8, then added to methanol according to a mass ratio of PET powder to methanol of 1:8, uniformly mixed, and then transferred to a ball mill tank made of stainless steel, and ball milling was performed at room temperature (25℃) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 90:1, the rotating speed was 800 rpm, and the time was 24 h); the ball mill tank was washed with dichloromethane, and a mixed solution was collected; the collected mixed solution was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 93.2%.
[0038] The dimethyl terephthalate obtained in Example 1 was a white crystalline solid, and the actual object diagram is shown in Figure 1 The dimethyl terephthalate obtained by grinding and degradation in Example 1 was subjected to nuclear magnetic testing, and a 1H NMR spectrum (CDCl3) was obtained, as shown in Figure 2 It can be seen from Figure 2 that the chemical shift value δ8.10 ppm corresponds to the hydrogen atoms on the benzene ring, the chemical shift value δ3.94 ppm corresponds to the hydrogen atoms on the methyl ester group, and the integral area ratio is 1:1.43, indicating that the degradation product is dimethyl terephthalate.
[0039] Example 2 PBT powder with an average particle size of 150 μm and a catalyst copper chromite were mixed according to a mass ratio of 1:1.5, then added to methanol according to a mass ratio of PBT powder to methanol of 1:8, uniformly mixed, and then transferred to a ball mill tank made of stainless steel, and ball milling was performed at room temperature (25℃) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PBT powder was 150:1, the rotating speed was 800 rpm, and the time was 24 h); the ball mill tank was washed with dichloromethane, and a mixed solution was collected; the collected mixed solution was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 90.4%.
[0040] Example 3 PET powder with an average particle size of 50 μm and catalyst chromium trioxide were mixed in a mass ratio of 1:1, and then added to methanol in a mass ratio of 1:4 of PET powder to methanol, mixed uniformly, and then transferred to a stainless steel ball mill tank. Ball milling was performed at room temperature (25°C) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 110:1, the rotation speed was 800 rpm, and the time was 24 h). The ball mill tank was rinsed with dichloromethane, and a mixed solution was collected. The collected mixed solution was subjected to silica gel column chromatography (the silica gel particle size was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 88.7%.
[0041] Comparative Example 1 PET was subjected to ball milling degradation according to the method of Example 1, except that no catalyst was added. The specific steps were as follows: PET powder with an average particle size of 50 μm and methanol were mixed in a mass ratio of 1:8, and then transferred to a stainless steel ball mill tank. Ball milling was performed at room temperature (25°C) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 90:1, the rotation speed was 800 rpm, and the time was 24 h). The ball mill tank was rinsed with dichloromethane, and a mixed solution was collected. The collected mixed solution was subjected to silica gel column chromatography (the silica gel particle size was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 31.1%.
[0042] Comparative Example 2 PET powder with an average particle size of 50 μm and methanol were mixed in a mass ratio of 1:70, and then transferred to a stainless steel ball mill tank. Ball milling was performed at room temperature (25°C) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 200:1, the rotation speed was 600 rpm, and the time was 6 h). The ball mill tank was rinsed with dichloromethane, and a mixed solution was collected. The collected mixed solution was subjected to silica gel column chromatography (the silica gel particle size was 200-300 mesh, and the mobile phase was dichloromethane), and no dimethyl terephthalate was obtained, with a yield of 0.
[0043] Comparative Example 3 PET was subjected to ball milling degradation according to the method of Example 1, except that copper oxide was used as the catalyst, and the mass ratio of PET to copper oxide was 1:1. The specific steps were as follows: PET powder with an average particle size of 50 μm and catalyst copper oxide were mixed in a mass ratio of 1:1, and then added to methanol in a mass ratio of 1:8 of PET powder to methanol, mixed uniformly, and then transferred to a ball mill tank made of stainless steel. Ball milling was performed at room temperature (25°C) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 90:1, the rotation speed was 800 rpm, and the time was 24 h). The ball mill tank was rinsed with dichloromethane, and a mixed solution was collected. The collected mixed solution was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 5.5%.
[0044] Comparative Example 4 PET was subjected to ball milling degradation according to the method of Comparative Example 3, except that aluminum oxide was used as the catalyst. The specific steps were as follows: PET powder with an average particle size of 50 μm and catalyst aluminum oxide were mixed in a mass ratio of 1:1, and then added to methanol in a mass ratio of 1:8 of PET powder to methanol, mixed uniformly, and then transferred to a ball mill tank made of stainless steel. Ball milling was performed at room temperature (25°C) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 90:1, the rotation speed was 800 rpm, and the time was 24 h). The ball mill tank was rinsed with dichloromethane, and a mixed solution was collected. The collected mixed solution was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 27.6%.
[0045] Comparative Example 5 (influence of the type of hydrogen donor) PET powder with an average particle size of 50 μm and catalyst copper chromite were mixed in a mass ratio of 1:1, and then added to isopropanol in a mass ratio of 1:8 of PET powder to isopropanol, mixed uniformly, and then transferred to a ball mill tank made of stainless steel. Ball milling was performed at room temperature (25°C) and in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PET powder was 150:1, the rotation speed was 800 rpm, and the time was 24 h). The ball mill tank was rinsed with dichloromethane, and a mixed solution was collected. The collected mixed solution was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane), and dimethyl terephthalate was obtained, with a yield of 2.3%.
[0046] Comparative Example 6 PBT was subjected to ball milling degradation according to the method of Example 2, except that no catalyst was added. The specific steps were as follows: PBT powder with an average particle size of 150 μm and methanol were mixed in a mass ratio of 1:8 and then transferred into a stainless steel ball mill tank. Ball milling was performed in an air atmosphere (the material of the grinding ball was stainless steel, the mass ratio of the grinding ball to the PBT powder was 110:1, the rotation speed was 800 rpm, and the time was 24 h). The ball mill tank was washed with dichloromethane to collect the product after ball milling. The washed mixture was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane) to obtain dimethyl terephthalate, and the yield was 13.6%.
[0047] Comparative Example 7 (influence of ball milling) 1 g of PET powder with an average size of 150 μm, 1 g of copper chromite catalyst, and 8 equivalents of methanol were added to a single-neck glass reaction flask, and magnetically stirred at room temperature for 24 h at a stirring speed of 500 rpm. The magnetically stirred system was washed with dichloromethane to collect the product. The collected mixture was subjected to silica gel column chromatography (the particle size of the silica gel was 200-300 mesh, and the mobile phase was dichloromethane), and no dimethyl terephthalate was obtained, and the yield was 0.
[0048] The degradation products obtained in Examples 2-3 were subjected to 1 H NMR testing, and the results were consistent with those of Example 1; the degradation products obtained in Comparative Examples 1 and 3-6 were subjected to 1 H NMR testing, and the results showed that the degradation products contained dimethyl terephthalate.
[0049] The dimethyl terephthalate obtained in Examples 1-3 and Comparative Examples 1-7 was weighed, and the yield of dimethyl terephthalate was calculated using the following formula: Yield (%) = (m 对苯二甲酸二甲酯 ÷ m PET ) × (M PET ÷ M 对苯二甲酸二甲酯 ) × 100% 对苯二甲酸二甲酯 PET PET 对苯二甲酸二甲酯 wherein m 对苯二甲酸二甲酯 is the mass of the obtained dimethyl terephthalate, m PET is the amount of PET fed, M PET = 192.2 g / mol, and M 对苯二甲酸二甲酯是 = 194.2 g / mol. When the polyester material is PBT, the above formula is also used, only M PET is replaced by M PBT , wherein M PBT = 220.2 g / mol.
[0050] The yield of the degradation products of Examples 1-3 and Comparative Examples 1-7 was calculated according to the above formula, and the results are shown in Table 1.
[0051] Table 1: Yield of degradation products of Examples 1-3 and Comparative Examples 1-7
[0052] As can be seen from the test results of the examples, the method provided by the present application can realize degradation of the polyester material, and has a higher yield of dimethyl terephthalate; the yield of dimethyl terephthalate obtained by the calculation method is an absolute yield, and the degradation method provided by the present application can obtain dimethyl terephthalate with a higher absolute yield, which indicates that the polyester material has a higher degradation rate.
[0053] Although the above examples have made a detailed description of the present application, it is only a part of the examples of the present application, but not all the examples, and people can also obtain other examples according to the present examples without creativity, which all belong to the protection scope of the present application.
Claims
1. A method for the degradation recycling of a polyester material, characterized in that, The method comprises the following steps: The polyester material, the catalyst and the hydrogen donor are mixed and then ball-milled to obtain dimethyl terephthalate; The catalyst comprises copper chromite or chromium trioxide; and the hydrogen donor is methanol.
2. The method of claim 1, wherein the polyester material is a polyethylene terephthalate (PET) material. The mass ratio of the polyester material to the hydrogen donor is 1:2-10.
3. The method of claim 1, wherein the polyester material is a polyethylene terephthalate (PET) material. The mass ratio of the polyester material to the catalyst is 0.5-2:0.1-2.
4. The method according to any one of claims 1 to 3, wherein the polyester material is a polyester resin. The polyester material comprises polyethylene terephthalate and / or polybutylene terephthalate. The average particle size of the polyester material is 50-150 μm.
5. The method of claim 1, wherein the polyester material is a polyethylene terephthalate (PET) material. The rotation speed of the ball-milling is 200-800 rpm, the ball-milling time is 6-24 h, the ball-milling temperature is room temperature, and the room temperature is 20-35 ℃.
6. The method of claim 1, wherein the polyester material is a polyethylene terephthalate (PET) material. The materials of the grinding balls and the ball-milling tank are respectively agate, stainless steel or zirconium oxide.
7. The method of claim 6, wherein the polyester material is a polyethylene terephthalate (PET) material. The mass ratio of the grinding balls to the polyester material is 50-150:1-2.
8. The method of claim 1, wherein the polyester material is a polyethylene terephthalate (PET) material. After the ball-milling, the system after the ball-milling and a solvent are mixed, and then solid-liquid separation is performed to obtain a solid phase and a liquid phase; the liquid phase is purified to obtain the dimethyl terephthalate.
9. The method of claim 8, wherein the polyester material is a polyethylene terephthalate (PET) material. The solid phase comprises the catalyst, and the solvent comprises ethanol and / or dichloromethane.
10. The method according to claim 8 or 9, wherein the polyester material is a polyester resin. The purification mode comprises silica gel column chromatography or recrystallization.