Degradation method of polyethylene glycol terephthalate
By using a ball milling method with polyoxometalate catalysts, PET is degraded into terephthalic acid and ethylene glycol, which solves the problem of high energy consumption in existing technologies and achieves efficient, low-energy, and green degradation. The catalyst can be recycled.
Patent Information
- Application Number
- CN202511497164.4
- 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
Existing PET recycling methods suffer from high energy consumption and demanding reaction conditions, making it difficult to achieve efficient, low-energy, and green degradation.
A polyoxometalate catalyst was mixed with polyethylene terephthalate and then ball-milled. Mechanical force was used to activate the chain and degrade it into terephthalic acid and ethylene glycol. The ball milling conditions were mild and did not require high temperature, high pressure or solvents.
It achieves a high degradation rate of polyethylene terephthalate (over 95%), a high yield of terephthalic acid (over 94%), and the catalyst can be recycled, making the degradation process green and environmentally friendly.
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Figure CN121107969A_ABST
Abstract
Description
TECHNICAL FIELD
[0002] The application belongs to the technical field of plastic waste treatment, and particularly relates to a degradation method of polyethylene terephthalate. BACKGROUND
[0003] Polyethylene terephthalate (PET) is a thermoplastic polyester plastic with excellent mechanical properties, chemical resistance and transparency, and is widely used in various fields. For example, in the packaging industry, due to its high mechanical strength, good gas barrier performance and recyclability, it is widely used in beverage bottles, food containers and fiber packaging materials; in the textile field, due to its wrinkle resistance, wear resistance and easy dyeing, it is often processed into polyester fibers and used in clothing, home textiles and industrial fabrics; in the electronics and automobile industries, due to its high dimensional stability and good insulation performance, it is used as an ideal material for capacitor films, insulating shells and lightweight structural components.
[0004] With the continuous growth of PET consumption, the environmental pressure brought by its waste is increasingly prominent, and the efficient recycling and degradation method of PET has become a key research direction in the field of plastic recycling. At present, the recycling methods of PET mainly include physical recycling and chemical degradation; physical recycling is mainly realized by melt regranulation, but multiple cycles will lead to a decrease in material performance; traditional chemical degradation mainly includes hydrolysis or alcoholysis, although PET can be degraded into terephthalic acid and ethylene glycol by hydrolysis or alcoholysis, but there are problems of harsh reaction conditions and high energy consumption in the recycling process. Therefore, developing an efficient, low-energy green degradation process to realize the high-value recycling of PET is a technical problem that needs to be solved urgently. SUMMARY
[0005] Therefore, the application provides a degradation method of polyethylene terephthalate, which can realize green and efficient degradation of polyethylene terephthalate with mild conditions and low energy consumption.
[0006] In order to solve the above technical problems, the application provides a degradation method of polyethylene terephthalate, which comprises the following steps: Mixing polyethylene terephthalate and a catalyst, and then ball milling to obtain terephthalic acid and ethylene glycol; The catalyst comprises a polyoxometalate.
[0007] Preferably, the polyoxometalate comprises one or more of phosphotungstic acid, phosphomolybdic acid, silicotungstic acid and silicomolybdic acid.
[0008] Preferably, the catalyst comprises catalyst particles, and the average particle size of the catalyst particles is 10-500 mesh.
[0009] Preferably, the polyethylene terephthalate includes polyethylene terephthalate powder, and the average particle size of the polyethylene terephthalate powder is 10-1000 mesh.
[0010] Preferably, the mass ratio of the polyethylene terephthalate and the catalyst is 1:0.2-3.
[0011] Preferably, the rotation speed of the ball mill is 200-1000 r / min, and the ball milling time is 4-36 h.
[0012] Preferably, the ball-to-material ratio of the ball mill is 50-500:1.
[0013] Preferably, the material of the ball mill tank and the grinding ball used in the ball mill includes stainless steel, zirconia or agate, respectively.
[0014] Preferably, after the ball milling, the system after the ball milling is further washed with water to obtain a mixed solution, and the mixed solution is subjected to solid-liquid separation to obtain a solid phase and a liquid phase. The liquid phase is a mixed solution of the catalyst and ethylene glycol, and the solid phase is terephthalic acid.
[0015] Preferably, after obtaining the liquid phase, the liquid phase is further dried to obtain a recovered catalyst, and the drying temperature is 40-90℃, and the drying time is 10-48 h.
[0016] The present application provides a degradation method of polyethylene terephthalate, including the following steps: mixing polyethylene terephthalate and a catalyst and then ball milling to obtain terephthalic acid and ethylene glycol; the catalyst includes a polyoxometalate. In the present application, the catalyst can directionally attack the ester group in the polyethylene terephthalate under the mechanical force activation of the ball mill, so that the chain is broken, and the polyethylene terephthalate is degraded into terephthalic acid and ethylene glycol. Compared with the existing chemical degradation method, the degradation method of polyethylene terephthalate provided in the present application does not require harsh reaction conditions such as high temperature and high pressure, nor any solvent, and has the advantages of high efficiency, low energy consumption, green environmental protection, etc., and the degradation product has high selectivity. The catalyst in the degradation method provided in the present application has high flexibility, and can be a polyoxometalate such as phosphotungstic acid, phosphomolybdic acid, silicotungstic acid and silicomolybdic acid; and the catalyst in the present application can be recycled. The degradation method provided in the present application has very high degradation rate and terephthalic acid yield; the degradation rate of the polyethylene terephthalate is more than 95%, and the yield of terephthalic acid is also more than 94%. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is the infrared spectrum of the filter cake in Example 1; Figure 2A columnar comparison chart of the degradation rates of PETs of Examples 1, 2 and 6 and Comparative Examples 1 and 3. DETAILED DESCRIPTION
[0018] The present application provides a polyethylene terephthalate degradation method, comprising the following steps: The polyethylene terephthalate and the catalyst are mixed and then ball-milled to obtain terephthalic acid and ethylene glycol.
[0019] As a specific embodiment of the present application, the polyethylene terephthalate can include polyethylene terephthalate powder, and the average particle size of the polyethylene terephthalate powder can be 10-1000 mesh, and can be specifically 50 mesh, 100 mesh, 200 mesh, 500 mesh or 800 mesh.
[0020] In the present application, the catalyst includes polyoxometalate; the polyoxometalate can include one or more of phosphotungstic acid, phosphomolybdic acid, silicotungstic acid and silicomolybdic acid, and can be specifically phosphotungstic acid, phosphomolybdic acid, silicotungstic acid or silicomolybdic acid; the catalyst can include catalyst particles, and the average particle size of the catalyst particles can be 10-500 mesh, and can be specifically 30 mesh, 50 mesh, 100 mesh, 200 mesh or 400 mesh.
[0021] As a specific embodiment of the present application, the mass ratio of the polyethylene terephthalate and the catalyst can be 1:0.2-3, and can be specifically 1:0.5, 1:1, 1:1.5, 1:2 or 1:2.5.
[0022] The mixing in the present application is not particularly limited as long as it can be uniformly mixed.
[0023] As a specific embodiment of the present application, the rotation speed of the ball-milling can be 200-1000 r / min, and can be specifically 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min or 900 r / min; the time of the ball-milling can be 4-36 h, and can be specifically 8 h, 10 h, 15 h, 18 h, 20 h, 25 h or 30 h; the ball-to-material ratio of the ball-milling can be 50-500:1, and can be specifically 100:1, 150:1, 200:1, 250:1, 300:1 or 400:1.
[0024] As a specific embodiment of the present application, the materials of the ball-milling tank and the grinding balls used in the ball-milling can respectively include stainless steel, zirconia or agate; the temperature of the ball-milling can be room temperature, and the temperature of the room temperature can be 20-35℃, and can also be 25-30℃; the atmosphere of the ball-milling can be air atmosphere.
[0025] As a specific embodiment of the present invention, the ball milling process may further include: rinsing the ball-milled system with water and collecting the mixture; performing solid-liquid separation on the mixture to obtain a solid phase and a liquid phase; the water may be deionized water; the solid-liquid separation may include filtration, and the present invention has no special requirements for the filtration, and conventional methods in the art can be used; the liquid phase is a mixed solution of catalyst and ethylene glycol, and the solid phase is terephthalic acid.
[0026] As a specific embodiment of the present invention, after obtaining the liquid phase, the method may further include: drying the liquid phase to obtain a recovered catalyst; the drying temperature may be 40~90℃, or 50~80℃, or even 60~75℃; the drying time may be 10~48h, or 15~40h, or even 24~30h.
[0027] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0028] Example 1 Polyethylene terephthalate powder with an average particle size of 100 mesh and phosphotungstic acid powder catalyst with an average particle size of 30 mesh were mixed at a mass ratio of 1:0.5 and then transferred to a zirconia ball mill jar for ball milling (speed 600 r / min, time 10 h, grinding ball material was zirconia, ball-to-material ratio was 100:1). After ball milling, the mixture was washed with deionized water and collected. The mixture was filtered, and the filtrate was catalyst and ethylene glycol solution, and the filter cake was terephthalic acid.
[0029] Example 2 Polyethylene terephthalate powder with an average particle size of 50 mesh and phosphotungstic acid powder catalyst with an average particle size of 30 mesh were mixed at a mass ratio of 1:1 and then transferred to a stainless steel ball mill jar for ball milling (rotation speed of 400 r / min, time of 18 h, grinding balls made of stainless steel, ball-to-material ratio of 200:1). After ball milling, the mixture was washed with deionized water and collected. The mixture was filtered, and the filtrate was catalyst and ethylene glycol solution, and the filter cake was terephthalic acid.
[0030] Example 3 Polyethylene terephthalate powder with an average particle size of 100 mesh and phosphomolybdic acid powder catalyst with an average particle size of 20 mesh were mixed at a mass ratio of 1:0.5 and then transferred to a zirconia ball mill jar for ball milling (speed 600 r / min, time 10 h, grinding ball material was zirconia, ball-to-material ratio was 100:1). After ball milling, the mixture was washed with deionized water and collected. The mixture was filtered, and the filtrate was catalyst and ethylene glycol solution, and the filter cake was terephthalic acid.
[0031] Example 4 Polyethylene terephthalate powder with an average particle size of 50 mesh and silicotungstic acid powder catalyst with an average particle size of 50 mesh were mixed at a mass ratio of 1:0.5 and then transferred to a stainless steel ball mill jar for ball milling (speed 600 r / min, time 10 h, grinding balls made of stainless steel, ball-to-material ratio 100:1). After ball milling, the mixture was washed with deionized water and collected. The mixture was filtered, and the filtrate was catalyst and ethylene glycol solution, and the filter cake was terephthalic acid.
[0032] Example 5 Polyethylene terephthalate powder with an average particle size of 50 mesh and molybdate silicosilicate powder catalyst with an average particle size of 50 mesh were mixed at a mass ratio of 1:0.5 and then transferred to a stainless steel ball mill jar for ball milling (speed 600 r / min, time 10 h, grinding balls made of stainless steel, ball-to-material ratio 100:1). After ball milling, the mixture was washed with deionized water and collected. The mixture was filtered, and the filtrate was catalyst and ethylene glycol solution, and the filter cake was terephthalic acid.
[0033] Example 6 The polyethylene terephthalate powder was degraded according to the method of Example 1, except that the mass ratio of polyethylene terephthalate to the catalyst phosphotungstic acid was 1:2.
[0034] Comparative Example 1 The polyethylene terephthalate powder was degraded according to the method in Example 1, except that no catalyst was added and the polyethylene terephthalate powder was simply ball-milled.
[0035] Comparative Example 2 The polyethylene terephthalate powder was degraded according to the method of Example 1, except that the phosphotungstic acid catalyst was replaced with tungstic acid.
[0036] Comparative Example 3 The polyethylene terephthalate powder was degraded according to the method of Example 1, except that the mass ratio of polyethylene terephthalate to the catalyst phosphotungstic acid was 1:0.1.
[0037] Comparative Example 4 The polyethylene terephthalate powder was degraded according to the method in Example 1, except that the ball milling time was 1 hour.
[0038] Comparative Example 5 The polyethylene terephthalate powder was degraded according to the method in Example 1, except that the ball milling speed was 100 r / min.
[0039] Infrared detection was performed on the filter cake in Example 1 to obtain an infrared spectrum, as shown below. Figure 1 As shown. By Figure 1 It can be seen that the main component of the filter cake in Example 1 is terephthalic acid, indicating that the degradation method provided by the present invention can effectively degrade polyethylene terephthalate into terephthalic acid.
[0040] The filter cakes from Examples 1-6 and Comparative Examples 1-5 were mixed with a 1 mol / L sodium hydroxide solution, filtered to remove a small amount of undegraded polyethylene terephthalate (PET) powder, dried, and weighed. The degradation rate was obtained by subtracting the mass of undegraded PET from the initial mass of PET to be degraded, and then dividing the result by the initial mass of PET to be degraded. Hydrochloric acid was added to the sodium hydroxide solution filtrate to precipitate terephthalic acid solids, which were then filtered, dried, and weighed. The yield was obtained by dividing the mass of the precipitate by the theoretical mass. The obtained degradation rates and yields are listed in Table 1.
[0041] Table 1. Degradation rate of PET and yield of terephthalic acid in Examples 1-6 and Comparative Examples 1-5
[0042] A bar chart comparing the degradation rates of PET in Examples 1, 2, and 6, and Comparative Examples 1 and 3, was plotted in Table 1. Figure 2 As shown.
[0043] Combining Table 1 and Figure 2 It can be seen that the degradation method provided by the present invention can efficiently degrade polyethylene terephthalate, with a degradation rate of over 95% and a yield of over 94% of terephthalic acid obtained from the degradation; and the mass ratio of polyethylene terephthalate powder to catalyst affects the degradation rate of PET.
[0044] Example 7 The filtrate from Example 1 was dried at 60°C for 24 hours to obtain recovered phosphotungstic acid catalyst powder, with a recovery rate of 80%. Polyethylene terephthalate powder with an average particle size of 50 mesh and recycled phosphotungstic acid catalyst powder were mixed at a mass ratio of 1:0.5 and then transferred to a stainless steel ball mill jar for ball milling (600 r / min, 10 h, stainless steel grinding balls, ball-to-material ratio of 100:1). After ball milling, the mixture was washed with deionized water and collected. The mixture was then filtered, and the filtrate contained the catalyst and ethylene glycol solution, while the filter cake contained terephthalic acid.
[0045] In this embodiment, the degradation rate of polyethylene terephthalate was 98.5%, and the yield of terephthalic acid was 91%.
[0046] The present invention can recover the catalyst through simple drying, and the recovered catalyst can be recycled and still maintain good catalytic performance.
[0047] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for degrading polyethylene terephthalate, characterized in that, Includes the following steps: Polyethylene terephthalate and catalyst were mixed and then ball-milled to obtain terephthalic acid and ethylene glycol. The catalyst comprises polyoxometalates.
2. The method for degrading polyethylene terephthalate according to claim 1, characterized in that, The polyoxometalates include one or more of phosphotungstic acid, phosphotomolybdic acid, silicotungstic acid, and silicotomolybdic acid.
3. The method for degrading polyethylene terephthalate according to claim 1 or 2, characterized in that, The catalyst comprises catalyst particles, the average particle size of which is 10-500 mesh.
4. The degradation method of polyethylene terephthalate according to claim 1, characterized in that, The polyethylene terephthalate comprises polyethylene terephthalate powder, wherein the average particle size of the polyethylene terephthalate powder is 10-1000 mesh.
5. The method for degrading polyethylene terephthalate according to claim 1, 2, or 4, characterized in that, The mass ratio of polyethylene terephthalate to catalyst is 1:0.2~3.
6. The method for degrading polyethylene terephthalate according to claim 1, characterized in that, The ball mill rotates at a speed of 200-1000 r / min, and the milling time is 4-36 h.
7. The method for degrading polyethylene terephthalate according to claim 1 or 6, characterized in that, The ball-to-material ratio of the ball mill is 50~500:
1.
8. The method for degrading polyethylene terephthalate according to claim 7, characterized in that, The materials used for the grinding jar and grinding balls in the ball mill include stainless steel, zirconium oxide, or agate, respectively.
9. The method for degrading polyethylene terephthalate according to claim 8, characterized in that, The process after ball milling further includes: rinsing the ball-milled system with water and collecting the mixture; and performing solid-liquid separation on the mixture to obtain a solid phase and a liquid phase. The liquid phase is a mixed solution of catalyst and ethylene glycol, and the solid phase is terephthalic acid.
10. The method for degrading polyethylene terephthalate according to claim 9, characterized in that, After obtaining the liquid phase, the process further includes: drying the liquid phase to obtain the recovered catalyst; the drying temperature is 40~90℃ and the time is 10~48h.