A method of polyethylene terephthalate aminolysis
By reacting polyethylene terephthalate with ammonia under mild conditions to produce terephthalic acid and other products, the problem of the difficulty in decomposing waste polyester is solved, and the value-added utilization and efficient treatment of waste polyester are realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
AI Technical Summary
Waste polyester plastics are chemically stable and difficult to decompose naturally, leading to environmental pressure. Existing recycling methods are inefficient and cannot effectively add value to their use.
Under mild conditions, by mixing polyethylene terephthalate with ammonia and reacting it in an inactive atmosphere, products such as terephthalic acid, terephthalic acid monoamide, and terephthalamide are generated, thereby realizing the value-added utilization of polyester.
It realizes the value-added utilization of polyester, producing amide organic chemicals as a byproduct while producing terephthalic acid. It has economic potential and environmental friendliness, with high processing efficiency and low energy consumption.
Abstract
Description
Technical Field
[0001] This application relates to a method for ammonolysis of polyethylene terephthalate, belonging to the field of plastics processing. Background Technology
[0002] With the increasing prevalence of plastic products in daily life, the production of polyester plastics has also increased rapidly. How to handle the resulting waste polyester has gradually attracted attention. Although waste polyester does not directly pollute the environment, its high chemical stability means it cannot decompose naturally in a short time, putting significant pressure on the environment. To achieve sustainable development, recycling waste polyester has become a key research focus for researchers worldwide. Currently, waste polyester recycling methods mainly fall into two categories: physical recycling and chemical recycling. Based on different depolymerization pathways, chemical recycling methods can be further divided into hydrolysis, alcohol hydrolysis, ammonolysis, and other methods. Introducing active functional groups to add value to polyester and achieving value-added utilization of waste plastics is a key research focus at present. Summary of the Invention
[0003] To address the aforementioned problems, the purpose of this invention is to develop a method for ammonolysis of polyethylene terephthalate (PET), which degrades PET and introduces amide functional groups under mild conditions. This method is of great significance for treating environmental pollution and enhancing the value of waste plastics.
[0004] According to one aspect of this application, a method for ammonolysis of polyethylene terephthalate is provided, comprising the following steps:
[0005] The raw material containing polyethylene terephthalate was mixed with ammonia water and reacted in a closed container under an inert gas atmosphere to obtain a product containing terephthalic acid, terephthalic acid monoamide, and terephthalamide.
[0006] The polyethylene terephthalate is selected from at least one of commercial polyethylene terephthalate, polyethylene terephthalate after processing waste mineral water bottles, and polyethylene terephthalate after processing waste packaging bags.
[0007] The particle size of the polyethylene terephthalate is less than 1 mm.
[0008] The solid-liquid ratio of the polyethylene terephthalate to ammonia is 0.02–0.05 g / ml.
[0009] The inert gas atmosphere includes a nitrogen atmosphere and an inert gas atmosphere;
[0010] The pressure of the inactive gas atmosphere is 0–2 MPa.
[0011] The concentration of the ammonia solution is 10–30 wt%.
[0012] The reaction temperature is 100–200°C;
[0013] The reaction time is 1 to 24 hours.
[0014] The sealed container is a sealed high-pressure reactor, and the amount of polyethylene terephthalate processed in the sealed high-pressure reactor is 0.1 to 2.0 g.
[0015] The beneficial effects that this application can produce include:
[0016] This invention develops a method for the ammonolysis of polyethylene terephthalate (PET). Utilizing ammonia water as the ammonia source, nitrogen is introduced into the degradation products of PET, achieving value-added utilization of PET and providing a new approach for the value-added utilization of other plastic waste. This method enables the value-added utilization of waste plastics, producing terephthalic acid while simultaneously generating amide-based organic chemicals as byproducts. It has economic potential, is environmentally friendly, and has high processing efficiency. The ammonolysis method for waste PET provided by this invention has low energy consumption, providing important protection for the sustainable development of my country's environment and economy, and proposing a convenient route for the ammonolysis of PET. Detailed Implementation
[0017] The following details this application, but this application is not limited to these.
[0018] Unless otherwise specified, all raw materials used in this application were purchased through commercial channels.
[0019] The polyethylene terephthalate used in this application is selected from at least one of commercial polyethylene terephthalate, polyethylene terephthalate obtained from the treatment of waste mineral water bottles, and polyethylene terephthalate obtained from the treatment of waste packaging bags. Among them, the two types of polyethylene terephthalate obtained from waste packaging bags need to be washed and dried with deionized water before use.
[0020] After the reaction, the mixed solids of terephthalic acid, terephthalic acid monoamide, and terephthalamide were dissolved in dimethyl sulfoxide, and the liquid products were analyzed using a reversed C18 column of liquid chromatography.
[0021] Example 1
[0022] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 120 °C using electric heating while stirring magnetically at 1000 rpm, and react for 720 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen gas, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform high-performance liquid chromatography (HPLC) analysis.
[0023] The yields obtained were: terephthalamide (18.7 wt%), terephthalic acid monoamide (59.6 wt%), and terephthalic acid (21.6 wt%).
[0024] Example 2
[0025] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 120 °C using electric heating while stirring magnetically at 1000 rpm, and react for 120 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen gas, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform high-performance liquid chromatography (HPLC) analysis.
[0026] The yields obtained were: terephthalamide (6.5 wt%), terephthalic acid monoamide (8.8 wt%), and terephthalic acid (2.3 wt%).
[0027] Example 3
[0028] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 110 °C using electric heating while stirring magnetically at 1000 rpm, and react for 120 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen gas, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform high-performance liquid chromatography (HPLC) analysis.
[0029] The yields obtained were: terephthalamide (2.2 wt%), terephthalic acid monoamide (2.3 wt%), and terephthalic acid (0.5 wt%).
[0030] Example 4
[0031] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 150 °C using electric heating while stirring magnetically at 1000 rpm, and react for 120 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen gas, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform high-performance liquid chromatography (HPLC) analysis.
[0032] The yields obtained were: terephthalamide (16.7 wt%), terephthalic acid monoamide (36.2 wt%), and terephthalic acid (13.4 wt%).
[0033] Example 5
[0034] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 140 °C using electric heating while stirring magnetically at 1000 rpm, and react for 120 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform high-performance liquid chromatography (HPLC) analysis.
[0035] The yields obtained were: terephthalamide (16.5 wt%), terephthalic acid monoamide (28.7 wt%), and terephthalic acid (8.8 wt%).
[0036] Example 6
[0037] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 130 °C using electric heating while stirring magnetically at 1000 rpm, and react for 120 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform liquid chromatography analysis.
[0038] The yields obtained were: terephthalamide (11.9 wt%), terephthalic acid monoamide (18.9 wt%), and terephthalic acid (5.4 wt%).
[0039] Example 7
[0040] Weigh 1.0 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.5 MPa nitrogen. Heat to 393 °C using electric heating while stirring at 1000 rpm for 120 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 100 g of DMSO solvent, and perform liquid chromatography analysis.
[0041] The yields obtained were: terephthalamide (16.1 wt%), terephthalic acid monoamide (50.3 wt%), and terephthalic acid (18.6 wt%).
[0042] Example 8
[0043] Weigh 0.25 g of polyethylene terephthalate and 10 mL of ammonia water and add them to a 50 mL high-pressure reactor. Seal the reactor, purge the air inside with nitrogen, and finally fill with 0.1 MPa nitrogen. Heat to 120 °C using electric heating while stirring magnetically at 1000 rpm, and react for 720 min. After the reaction is complete, stop stirring, place the reactor in an ice-water bath to cool for 30 min, purge the nitrogen gas, and then open the reactor. Place the product in an 80 °C oven to remove the ammonia water, dissolve the dried solid in 40 g of DMSO solvent, and perform high-performance liquid chromatography (HPLC) analysis.
[0044] The yields obtained were: terephthalamide (18.6 wt%), terephthalic acid monoamide (59.3 wt%), and terephthalic acid (21.1 wt%).
[0045] The above description is merely one example of this application and does not constitute any limitation on this application. Although this application has been preferably disclosed above, it is not intended to limit this application. Any modifications or alterations made by those skilled in the art without departing from the scope of the technical solution disclosed above are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A method for ammonolysis of polyethylene terephthalate, characterized in that, Includes the following steps: The raw material containing polyethylene terephthalate was mixed with ammonia water and reacted in a closed container under an inert gas atmosphere to obtain a product containing terephthalic acid, terephthalic acid monoamide, and terephthalamide. The polyethylene terephthalate is selected from at least one of commercial polyethylene terephthalate, polyethylene terephthalate after processing waste mineral water bottles, and polyethylene terephthalate after processing waste packaging bags.
2. The method according to claim 1, characterized in that, The particle size of the polyethylene terephthalate is less than 1 mm.
3. The method according to claim 1, characterized in that, The solid-liquid ratio of the polyethylene terephthalate to ammonia is 0.02–0.05 g / ml.
4. The method according to claim 1, characterized in that, The inert gas atmosphere includes a nitrogen atmosphere and an inert gas atmosphere; The pressure of the inactive gas atmosphere is 0–2 MPa.
5. The method according to claim 1, characterized in that, The concentration of the ammonia solution is 10–30 wt%.
6. The method according to claim 1, characterized in that, The reaction temperature is 100–200°C; The reaction time is 1 to 24 hours.