A method for preparing micron carbon spheres from waste plastics
The preparation of microcarbon spheres by high-temperature pyrolysis and high-pressure carbonization treatment of waste plastics has been solved, and the cost and complexity of the preparation of high-quality carbon materials in the prior art has been achieved, and efficient and low-cost microcarbon sphere preparation is achieved.
Patent Information
- Application Number
- CN202410737134.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-07
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2044-06-07
AI Technical Summary
The prior art is difficult to efficiently use waste plastic to prepare high-quality carbon materials, and the traditional methods are costly and complex.
The waste plastic is treated by high-temperature pyrolysis and high-pressure carbonization, and first convert it into pyrolytic oil, and then prepare micron carbon balls under a sealed high-pressure environment to simplify the process and improve the purity.
It realizes efficient and low-cost preparation of high-purity microcarbon carbon balls, simplifies the process flow and reduces production costs.
Smart Images
Figure CN118343743B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of waste treatment, and relates to a method for the high-value utilization of waste plastics, in particular to a method for preparing micron-sized carbon spheres from waste plastics. Background Art
[0002] Plastics are widely used due to their low cost, convenience, and excellent performance. However, a large amount of waste plastics are generated and need to be treated urgently. Waste plastics are difficult to biodegrade and accumulate continuously in the natural environment or landfills, which not only causes waste of carbon resources but also leads to serious environmental pollution problems. Currently, the main plastic recycling methods include mechanical recycling, incineration, and pyrolysis. These traditional treatment methods cannot efficiently utilize the value of waste plastics.
[0003] Carbon materials have the advantages of good electrical conductivity, thermal conductivity, and strong structural plasticity, and are widely used in catalysis, energy storage, pollutant purification, etc. Plastics have a high carbon content and are ideal raw materials for preparing carbon materials. Preparing carbon materials such as carbon spheres, carbon nanotubes, and porous carbon from waste plastics is a current research hotspot. Currently, the main method for preparing carbon materials from waste plastics is chemical vapor deposition. However, the preparation of catalysts by chemical vapor deposition is complex, costly, and difficult to recycle. It is urgent to develop a method for preparing waste plastic-based carbon materials with a simple process and high economy. Summary of the Invention
[0004] The present invention aims to provide a method for preparing micron carbon spheres from waste plastics, which can solve the problems of poor structural properties and high impurity content of carbon materials prepared from waste plastics.
[0005] To achieve the above object, the technical solution of the present invention is as follows:
[0006] A method for preparing micron carbon spheres from waste plastics, comprising the following steps:
[0007] (1) Thermally decomposing waste plastics under an inert atmosphere at a high temperature to obtain pyrolysis oil;
[0008] (2) Carbonizing the pyrolysis oil at a high temperature under a closed and high-pressure environment to obtain micron carbon spheres.
[0009] Preferably, the waste plastics in step (1) are one or more of LDPE, HDPE, PP, PS, PET, or PVC.
[0010] Preferably, the inert atmosphere in step (1) is a nitrogen atmosphere, a helium atmosphere, or an argon atmosphere.
[0011] Preferably, the temperature of the high-temperature thermal decomposition in step (1) is 450-550 °C.
[0012] Preferably, step (1) further includes the step of recovering the pyrolysis gas and solid residues generated by high-temperature pyrolysis.
[0013] Preferably, when the waste plastics described in step (1) contain PVC, step (1) further includes a pre-dechlorination step before the high-temperature pyrolysis, and the pre-dechlorination is carried out at 300 °C for 30 min.
[0014] Preferably, step (2) is carried out in a closed high-pressure reactor.
[0015] Preferably, the high-pressure reactor is made of stainless steel, with a maximum working temperature of 800 °C and a pressure resistance of more than 10 MPa.
[0016] Preferably, the temperature of the high-temperature carbonization in step (2) is 600 - 700 °C, and the reaction time of the high-temperature carbonization is 0.5 - 1 hour.
[0017] Preferably, step (2) further includes the step of recovering the gas generated by high-temperature carbonization. In step (2), only solid and gas products are generated in the carbonization reaction. The solid is mainly spherical carbon materials with a size of 2 - 8 μm; when the waste plastics do not contain PET, the methane content in the gas product is > 95%, and when the waste plastics contain PET, CO and CO2 are generated.
[0018] Compared with the existing technologies, the present invention innovatively converts waste plastics into pyrolysis oil by chemical pyrolysis before carbonization, and uses the phase separation of solid, liquid and gas products to simply and conveniently remove solid impurities, thereby improving the purity of pyrolysis oil. Further, pyrolysis oil is used to prepare micron carbon spheres, improving the purity and quality of carbon materials. Compared with the previous recycling and treatment methods, this method does not require catalysts and solvents, has a simple process, low cost and high-value products. Description of the Drawings
[0019] Figure 1 It is a scanning electron microscope photograph of waste plastic-based carbon spheres in Example 1.
[0020] Figure 2 It is an XRD spectrum of waste plastic-based carbon spheres in Example 1.
[0021] Figure 3 It is a scanning electron microscope photograph of the solid phase product obtained in Comparative Example 2.
[0022] Figure 4 It is an XRD spectrum of the solid phase product obtained in Comparative Example 2. Detailed Description of the Invention
[0023] The present invention will be described in detail below in conjunction with specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. Example
[0024] The mixed waste plastics (containing 23.5% LDPE, 17.4% HDPE, 26.6% PP, 8.2% PS, 11.3% PET, 13.0% PVC) were crushed and then placed in a tubular furnace for high-temperature pyrolysis. The heating rate was controlled at 5 °C −1 , and the flow rate of the protective gas N2 was 50 mL / min −1 . After heating to 450 °C, it was kept warm for 0.5 h. The pyrolysis oil was collected using a cold trap. The pyrolysis oil was put into a high-pressure reactor for carbonization, and the heating rate was 5 °C −1 , heated to 700 °C and kept warm for 30 min. After cooling, the reactor was opened to collect the three-phase products. The yield of the gas-phase product was 45%, the solid-phase product was 55%, and no liquid-phase product was formed. The morphology of the solid-phase product is as Figure 1 shown, mainly monodisperse carbon spheres with a diameter of 2 - 8 μm and a carbon element content of 93.7%. The XRD pattern of the solid-phase product is as Figure 2 shown, only the diffraction peaks of graphite carbon appear, and no impurity diffraction peaks are present. The methane content in the gas-phase product is 91%, which can be used as fuel gas.
[0025] The mixed waste plastics were treated in the same way as in Example 1, except that the carbonization reaction did not use a high-pressure reactor, but a conventional tubular furnace, and the flow rate of the protective gas N2 was 50 mL / min −1 , and the heating rate was 5 °C −1 , heated to 700 °C and kept warm for 30 min. After the reaction, the pyrolysis oil was completely gasified, and no solid carbon material was formed.
[0026] The mixed waste plastics were treated in the same way as in Example 1, except that the high-temperature pyrolysis reaction was not carried out, and the mixed waste plastics were directly added to the high-pressure reactor for carbonization reaction. After the reaction, the three-phase products were collected. The yield of the gas-phase product was about 50%, and the rest was the solid-phase product. The morphology of the solid-phase product is as Figure 3 shown, mainly massive products, containing a small amount of carbon spheres. The XRD pattern of the solid-phase product is as Figure 4 shown, mainly the diffraction peaks of CaCO3, and almost no graphite carbon diffraction peaks can be seen. CaCO3 is a commonly used plastic filler and remains in the solid-phase product, making it difficult to separate.
Claims
1. A method for preparing micron carbon spheres from waste plastics, characterized in that, It includes the following steps: (1) High-temperature pyrolysis of waste plastics in an inert atmosphere to obtain pyrolysis oil, and recovering the pyrolysis gas and solid residues generated by the high-temperature pyrolysis; the temperature of the high-temperature pyrolysis is 450-550 °C; (2) High-temperature carbonization of the pyrolysis oil in a closed and high-pressure environment to obtain micron carbon spheres; the temperature of the high-temperature carbonization is 600-700 °C, and the reaction time of the high-temperature carbonization is 0.5-1 hour.
2. The method according to claim 1, wherein The waste plastics described in step (1) are one or more of LDPE, HDPE, PP, PS, PET or PVC.
3. The method according to claim 1, characterized in that, The inert atmosphere described in step (1) is a nitrogen atmosphere, a helium atmosphere or an argon atmosphere.
4. The method according to claim 1, characterized in that, When the waste plastics described in step (1) contain PVC, step (1) further includes a pre-dechlorination step before the high-temperature pyrolysis, and the pre-dechlorination is to react at 300 °C for 30 min.
5. The method according to claim 1, wherein Step (2) is carried out in a closed high-pressure reactor.
6. The method according to claim 5, wherein The high-pressure reactor is made of stainless steel, with a maximum working temperature above 800 °C and a pressure resistance above 10 MPa.
7. The method according to claim 1, characterized in that, Step (2) further includes a step of recovering the gas generated by the high-temperature carbonization.