Method for degrading bio-based furan polyester by gamma rays

Abstract

The invention relates to the field of degradation and recovery of new polyester materials, in particular to a method for degrading bio-based furan polyester by gamma rays, which comprises the following steps: step 1, preparation of bio-based furan polyester waste particles, step 2, degradation of bio-based furan polyester molecular chains, and step 3, purification and separation of alcoholysis products. According to the method, ozone molecules are excited by utilizing the high-energy radiation characteristic of gamma rays, so that the ozone molecules are changed from a stable state to an excited state, extremely strong oxidation capacity is generated, and bio-based furan polyester macromolecular chains are degraded. According to the method, the polyester waste is subjected to two-stage degradation, so that macromolecular chains are gradually decomposed into oligomers, and finally monomers are generated. The method is simple, efficient and pollution-free.

Description

Technical Field

[0001] The invention relates to the field of degradation and recovery of new polyester materials, in particular to a method for degrading bio-based furan polyester by using gamma rays. Background Art

[0002] Bio-based furan polyesters are made from esterification-polycondensation of 2,5-furandicarboxylic acid (2,5-FDCA) and diols. Its monomer 2,5-furandicarboxylic acid (2,5-FDCA) is the only compound with an aromatic ring among the 12 bio-based platform compounds and is considered to be the most likely aromatic bio-based monomer to replace terephthalic acid (PTA). Therefore, the research on bio-based furan polyesters has gradually increased, and there are mature market products. However, due to the high cost of its monomer 2,5-furandicarboxylic acid (2,5-FDCA) and the difficulty in controlling the color and molecular weight during the synthesis process, a large amount of finished products are wasted. Recycling, degradation and reuse of its waste has both economic value and social significance.

[0003] There are a large number of patents for the degradation of petroleum-based polyesters in the existing technology, which are mainly divided into chemical methods and biological methods. The chemical method mainly generates oligomers or monomers through chemical reactions of ethylene glycol, methanol, water, etc. under high temperature, high pressure and catalyst conditions to achieve the purpose of reuse; the biological method mainly degrades the polyester macromolecular chain through the fermentation degradation of enzyme preparations to obtain related oligomers and monomers.

[0004] For example: Patent CN 115103874 A relates to a chemical recycling method, which can produce packaging materials and / or textile materials using colorless bis(hydroxyethyl) terephthalate (BHET) obtained from packaging waste containing polyester and / or textiles produced from up to 50% polyester and including up to 50 ppm of colorants or fillers. The specific method is: monoethylene glycol (MEG) and textiles and / or polyester-based packaging waste made of at least 50% polyester materials in a ratio of 2:1-7:1 are transferred to a depolymerization reactor, preferably zinc acetate or sodium hydroxide is added to the reactor as a catalyst, and reacted at a temperature of 180-270°C for 5 hours. At the end of the depolymerization process, a mixture of bis(hydroxyethyl) terephthalate (BHET), monoethylene glycol (MEG) and a colorant is obtained, and then bis(hydroxyethyl) terephthalate (BHET) is obtained after filtration-centrifuge separation-activated carbon adsorption-centrifuge separation. The method has a cumbersome recovery process, high production cost, and fails to obtain the required monomer, which greatly limits the scope of recovery and utilization.

[0005] For example, patent CN 103074386 A involves a biological recovery method, which uses enzyme catalysis in ionic liquid to recover aliphatic polyester and its repolymerization. The recovery method includes: adding aliphatic polyester powder, ionic liquid, and distilled water into a conical flask and performing ultrasonic treatment; then adding lipase to react at a constant temperature for 4-48 hours; filtering, recovering the enzyme, adding chloroform, toluene, tetrahydrofuran, ethanol, acetone or water to the filtrate to extract the degradation product, then standing and stratifying, separating the liquids to obtain a degradation product solution, and recovering the ionic liquid; the degradation product solution is distilled under reduced pressure to obtain a light yellow liquid, which is the degradation product. This method requires the use of a large amount of organic solvents, which seriously pollutes the environment and does not conform to the industry development trend of green environmental protection.

[0006] There are relatively few studies on the chemical and biological methods of recycling and degrading bio-based furan polyesters, and no related patents have been reported. Summary of the invention

[0007] In order to solve the above technical deficiencies, the present invention provides a method for degrading bio-based furan polyester by using gamma rays, and the degradation process is environmentally friendly and highly efficient.

[0008] The present invention discloses a method for degrading bio-based furan polyester by using gamma rays, comprising the following steps:

[0009] Step 1: Preparation of bio-based furan polyester waste pellets,

[0010] 1.1, send the bio-based furan polyester waste into a pulverizer for pulverization, and obtain waste particles after filtering through a filter screen with a filter screen accuracy of 500-1000μm;

[0011] Step 2: Degradation of bio-based furan polyester molecular chains,

[0012] 2.1, soaking the bio-based furan polyester waste particles in an ethylene glycol solution at 70-200° C. for ultrasonic swelling, the ultrasonic frequency is 20-80 kHz, the weight ratio of the waste particles to ethylene glycol is 1:10-100, and the swelling time is 10-100 min;

[0013] 2.2, the swollen bio-based furan polyester waste particles are filtered through a filter screen and then sent into a closed space filled with ozone. The filter screen has an accuracy of 500-1000 μm and an ozone concentration of 0.02-20 ppm. The particles are irradiated with gamma rays at a temperature of 100-190°C, with an irradiation dose of 1-20 Gy, and the reaction is terminated after irradiation for 1-10 minutes;

[0014] 2.3, feeding the bio-based furan polyester waste particles after the reaction into an alcoholysis reactor, mixing with ethylene glycol, and then filling the alcoholysis reactor with ozone gas, the mass ratio of the waste particles to the ethylene glycol is 1:0.5-10, the ozone content in the alcoholysis solution is 0.1-10ppm, and the mixed solution is subjected to alcoholysis reaction at 140-180°C for 30-80min to obtain a mixture containing monomers and oligomers;

[0015] Step 3: purification and separation of alcoholysis products,

[0016] 3.1, feeding the mixture containing monomers and oligomers into a separation kettle, adding a crystallizing agent, the amount of the crystallizing agent being 0.1-10% of the mass of the mixture, and the crystallizing agent forming a colloid with the monomers in the mixture;

[0017] 3.2, sending the mixture after adding the crystallization agent in 3.1 into a centrifuge, and rotating and separating at 60-100° C., the centrifuge speed is 3000-5000 rpm, and the mixture is separated into layers after centrifugation;

[0018] 3.3, the layered mixture is subjected to secondary filtration, the primary filtration accuracy is 300-500μm, and the secondary filtration accuracy is 100-300μm;

[0019] 3.4, the precipitate after secondary filtration is a colloid, which is dissolved in water at 10-50°C, with a weight ratio of colloid to water of 1:50-100. After being fully dissolved, it is sent to a filter with a filter precision of 50-100 μm. The filtered precipitate is dried to obtain a monomer powder; the filtered aqueous solution is evaporated and purified at 100-110°C to obtain a crystallizing agent;

[0020] 3.5, send the solution after secondary filtration in 3.3 to a reboiler for evaporation and purification, the reboiler temperature is 200-230°C, and ethylene glycol is obtained after steam cooling.

[0021] In step 2.1, the temperature of ethylene glycol is 80-120°C.

[0022] In step 2.2, the energy source for generating gamma rays is one or more of iron 55, cobalt 57, cobalt 60, selenium 75, cesium 137, thulium 170, iridium 192, plutonium 238, and americium 241.

[0023] The crystallization agent is one of N,N-dimethylformamide and N,N-dimethylacetamide or a mixed solution of the two in any proportion.

[0024] The method of using gamma rays to degrade bio-based furan polyester obtained by the present invention has the advantages of high efficiency, environmental protection and low cost. The high-energy gamma rays used in the degradation process react with ozone without any residue and without generating pollutants. The monomers obtained by deep degradation can be reused in subsequent reactions, thus greatly saving production costs.

[0025] The present invention provides a new method for degrading bio-based furan polyester, which uses high-energy gamma rays to depolymerize polyester molecular chains in the presence of ozone, a strong oxidant, and has the characteristics of high efficiency and no pollution. After subsequent treatment, 2,5-furandicarboxylic acid (2,5-FDCA) and diol monomers can be obtained, which greatly solves the problem that bio-based furan polyester is difficult to recycle and reuse at low cost and in a green manner. DETAILED DESCRIPTION

[0026] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation method, structure, characteristics and effects of the present invention are described in detail below in combination with the preferred embodiments.

[0027] Embodiment 1:

[0028] The present invention discloses a method for degrading bio-based furan polyester by using gamma rays, comprising the following steps:

[0029] Step 1, preparation of bio-based furan polyester waste particles,

[0030] 1.1, the bio-based furan polyester waste is sent to a pulverizer for pulverization, and the waste particles are obtained after filtering through a filter screen, and the filter screen accuracy is 1000μm;

[0031] Step 2, degradation of bio-based furan polyester molecular chains,

[0032] 2.1, the bio-based furan polyester waste particles were immersed in an ethylene glycol solution at 120°C for ultrasonic swelling, the ultrasonic frequency was 80kHz, the weight ratio of the waste particles to ethylene glycol was 1:100, and the swelling time was 100min;

[0033] 2.2, the swollen bio-based furan polyester waste particles are filtered through a filter screen and then sent into a closed space filled with ozone. The filter screen has an accuracy of 1000 μm and an ozone concentration of 20 ppm. The particles are irradiated with gamma rays at a temperature of 190°C, with an irradiation dose of 20 Gy and irradiation for 10 minutes to terminate the reaction. The energy source for generating gamma rays is iron 55;

[0034] 2.3, sending the bio-based furan polyester waste particles after the reaction into an alcoholysis reactor, mixing with ethylene glycol, and then filling the alcoholysis reactor with ozone gas, the mass ratio of the waste particles to ethylene glycol is 1:10, the ozone content in the alcoholysis solution is 10ppm, and the mixed solution is subjected to alcoholysis reaction at 180°C for 80min to obtain a mixture containing monomers and oligomers;

[0035] Step 3, purification and separation of alcoholysis products,

[0036] 3.1, feeding the mixture containing monomers and oligomers in 2.3 into a separation kettle, adding N,N-dimethylformamide, the amount of N,N-dimethylformamide is 10% of the mass of the mixture, and N,N-dimethylformamide forms a colloid with the monomers in the mixture;

[0037] 3.2, the mixture containing colloid in 3.1 is sent to a centrifuge for rotational separation at 100°C and a centrifuge speed of 5000 rpm. After centrifugation for 10 minutes, the mixture is separated into layers;

[0038] 3.3, the layered solution is subjected to secondary filtration, the primary filtration accuracy is 500μm, and the secondary filtration accuracy is 300μm;

[0039] 3.4, the precipitate after secondary filtration is a colloid, which is dissolved in water at 50°C, with the ratio of colloid to water being 1:100. After being fully dissolved, it is sent to a filter with a precision of 100μm. The filtered precipitate is dried to obtain monomer powder; the filtered aqueous solution is evaporated and purified at 110°C to obtain N,N-dimethylformamide again;

[0040] 3.5. Send the solution after secondary filtration in 3.3 to a reboiler for evaporation and purification. The reboiler temperature is 230°C. Ethylene glycol is obtained after steam cooling.

[0041] Embodiment 2:

[0042] The present invention discloses a method for degrading bio-based furan polyester by using gamma rays, comprising the following steps:

[0043] Step 1, preparation of bio-based furan polyester waste particles,

[0044] 1.1, the bio-based furan polyester waste is sent to a pulverizer for pulverization, and the waste particles are obtained after filtering through a filter screen with a filter screen accuracy of 800 μm;

[0045] Step 2, Degradation of Bio-based Furan Polyester Molecular Chains

[0046] 2.1, the bio-based furan polyester waste particles were immersed in an ethylene glycol solution at 110°C for ultrasonic swelling, the ultrasonic frequency was 80kHz, the weight ratio of the waste particles to ethylene glycol was 1:80, and the swelling time was 80min;

[0047] 2.2, the swollen bio-based furan polyester waste particles are filtered through a filter screen and then sent into a closed space filled with ozone. The filter screen has an accuracy of 800 μm and an ozone concentration of 15 ppm. The particles are irradiated with gamma rays at a temperature of 150°C and an irradiation dose of 15 Gy. The reaction is terminated after 8 minutes of irradiation. The energy source for generating gamma rays is cobalt 60.

[0048] 2.3, sending the bio-based furan polyester waste particles after the reaction into an alcoholysis reactor, mixing with ethylene glycol, and then filling the alcoholysis reactor with ozone gas, the mass ratio of the waste particles to the ethylene glycol is 1:5, the ozone content in the alcoholysis solution is 8ppm, and the mixed solution is subjected to alcoholysis reaction at 170°C for 70min to obtain a mixture containing monomers and oligomers;

[0049] Step 3, purification and separation of alcoholysis products,

[0050] 3.1, feeding the mixture containing monomers and oligomers in 2.3 into a separation kettle, adding N,N-dimethylacetamide, the amount of N,N-dimethylacetamide is 5% of the mass of the mixture, and N,N-dimethylacetamide forms a colloid with the monomers in the mixture;

[0051] 3.2, the mixture containing colloid in 3.1 is sent to a centrifuge for rotational separation at 90°C and a centrifuge speed of 4000 rpm. After centrifugation for 9 minutes, the mixture is separated into layers;

[0052] 3.3, the layered solution is subjected to secondary filtration, the primary filtration accuracy is 450μm, and the secondary filtration accuracy is 280μm;

[0053] 3.4, the precipitate after secondary filtration is a colloid, which is dissolved in water at 40°C, with the ratio of colloid to water being 1:80. After being fully dissolved, it is sent to a filter with a precision of 90μm. The filtered precipitate is dried to obtain monomer powder; the filtered aqueous solution is evaporated and purified at 106°C to obtain N,N-dimethylacetamide again;

[0054] 3.5. Send the solution after secondary filtration in 3.3 to a reboiler for evaporation and purification. The reboiler temperature is 225°C. Ethylene glycol is obtained after steam cooling.

[0055] Embodiment 3:

[0056] The present invention discloses a method for degrading bio-based furan polyester by using gamma rays, comprising the following steps:

[0057] Step 1, preparation of bio-based furan polyester waste particles,

[0058] 1.1, the bio-based furan polyester waste is sent to a pulverizer for pulverization, and the waste particles are obtained after filtering through a filter screen with a filter screen accuracy of 600 μm;

[0059] Step 2, degradation of bio-based furan polyester molecular chains,

[0060] 2.1, the bio-based furan polyester waste particles were immersed in a 100°C ethylene glycol solution for ultrasonic swelling, the ultrasonic frequency was 60kHz, the weight ratio of the waste particles to ethylene glycol was 1:50, and the swelling time was 50min;

[0061] 2.2, the swollen bio-based furan polyester waste particles are filtered through a filter screen and then sent into a closed space filled with ozone. The filter screen has an accuracy of 600 μm and an ozone concentration of 10 ppm. The particles are irradiated with gamma rays at a temperature of 130°C and an irradiation dose of 12 Gy. The reaction is terminated after 5 minutes of irradiation. The energy source for generating gamma rays is iridium 192.

[0062] 2.3, sending the bio-based furan polyester waste particles after the reaction into an alcoholysis reactor, mixing with ethylene glycol, and then filling the alcoholysis reactor with ozone gas, the mass ratio of the waste particles to the ethylene glycol is 1:2, the ozone content in the alcoholysis solution is 5ppm, and the mixed solution is subjected to alcoholysis reaction at 170°C for 50min to obtain a mixture containing monomers and oligomers;

[0063] Step 3, purification and separation of alcoholysis products,

[0064] 3.1, the mixture is sent into a separation kettle, and a mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide is added, the amount of the mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide is 2% of the mass of the mixture, and N,N-dimethylformamide and N,N-dimethylacetamide form a colloid with the monomers in the mixture;

[0065] 3.2, the mixture containing colloid in 3.1 is sent to a centrifuge for rotational separation at 80°C and a centrifuge speed of 3000 rpm. After centrifugation for 6 minutes, the mixture is separated into layers;

[0066] 3.3, the layered solution is subjected to secondary filtration, the primary filtration accuracy is 400μm, and the secondary filtration accuracy is 240μm;

[0067] 3.4, the precipitate after secondary filtration is a colloid, which is soluble in water at 35°C, with a colloid to water ratio of 1:70. After being fully dissolved, it is sent to a filter with a filter precision of 70μm. The filtered precipitate is dried to obtain a monomer powder; the filtered aqueous solution is evaporated and purified at 103°C to obtain a mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide;

[0068] 3.5, send the solution after secondary filtration in 3.3 to a reboiler for evaporation and purification. The reboiler temperature is 220°C. Ethylene glycol is obtained after steam cooling.

[0069] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simplified modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for degrading bio-based furan polyester using gamma rays, characterized in that it comprises the following steps: Step 1: Preparation of bio-based furan polyester waste pellets, 1.1, send the bio-based furan polyester waste into a pulverizer for pulverization, and obtain waste particles after filtering through a filter screen with a filter screen accuracy of 500-1000μm; Step 2: Degradation of bio-based furan polyester molecular chains, 2.1, soaking the bio-based furan polyester waste particles in an ethylene glycol solution at 70-200° C. for ultrasonic swelling, the ultrasonic frequency is 20-80 kHz, the weight ratio of the waste particles to ethylene glycol is 1:10-100, and the swelling time is 10-100 min; 2.2, the swollen bio-based furan polyester waste particles are filtered through a filter screen and then sent into a closed space filled with ozone. The filter screen has an accuracy of 500-1000 μm and an ozone concentration of 0.02-20 ppm. The particles are irradiated with gamma rays at a temperature of 100-190°C, with an irradiation dose of 1-20 Gy, and the reaction is terminated after irradiation for 1-10 minutes; 2.3, feeding the bio-based furan polyester waste particles after the reaction into an alcoholysis reactor, mixing with ethylene glycol, and then filling the alcoholysis reactor with ozone gas, the mass ratio of the waste particles to the ethylene glycol is 1:0.5-10, the ozone content in the alcoholysis solution is 0.1-10ppm, and the mixed solution is subjected to alcoholysis reaction at 140-180°C for 30-80min to obtain a mixture containing monomers and oligomers; Step 3: purification and separation of alcoholysis products, 3.1, feeding the mixture containing monomers and oligomers into a separation kettle, adding a crystallizing agent, the amount of the crystallizing agent being 0.1-10% of the mass of the mixture, and the crystallizing agent forming a colloid with the monomers in the mixture; 3.2, the mixture after adding the crystallization agent in 3.1 is sent to a centrifuge for rotational separation at 60-100° C., the centrifuge speed is 3000-5000 rpm, and the mixture is separated into layers after centrifugation; 3.3, the layered mixture is subjected to secondary filtration, the primary filtration accuracy is 300-500μm, and the secondary filtration accuracy is 100-300μm; 3.4, the precipitate after secondary filtration is a colloid, which is dissolved in water at 10-50°C, with a weight ratio of colloid to water of 1:50-100. After being fully dissolved, it is sent to a filter with a filter precision of 50-100 μm. The filtered precipitate is dried to obtain a monomer powder; the filtered aqueous solution is evaporated and purified at 100-110°C to obtain a crystallizing agent; 3.5, send the solution after secondary filtration in 3.3 to a reboiler for evaporation and purification, the reboiler temperature is 200-230°C, and ethylene glycol is obtained after steam cooling.

2. The method for degrading bio-based furan polyester using gamma rays according to claim 1, characterized in that: in step 2.1, the temperature of ethylene glycol is 80-120°C.

3. The method for degrading bio-based furan polyester using gamma rays according to claim 1, characterized in that: In step 2.2, the energy source for generating gamma rays is one or more of iron 55, cobalt 57, cobalt 60, selenium 75, cesium 137, thulium 170, iridium 192, plutonium 238, and americium 241.

4. The method for degrading bio-based furan polyester using gamma rays according to claim 1, characterized in that: The crystallization agent is one of N,N-dimethylformamide and N,N-dimethylacetamide or a mixed solution of the two in any proportion.