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How is plastic chemically recycled?
The recycling methods of waste plastics mainly include physical methods and chemical methods. The physical method mainly refers to the mechanical recycling of waste plastics, which is the main method of recycling waste plastics at present. Chemical law: Chain breaking reactions and other oxidative degradation processes under the action of catalysts (chemical catalysts or biological enzyme catalysts) convert waste plastic polymers into small molecules. These small molecules can be recycled to make other polymeric materials as well as alternative chemical raw materials, providing pioneering solutions for repurposing waste plastics and contributing innovative sustainable materials to drive our plastics economic transformation.
Coperion supplied the University of Ghent in Belgium with an extrusion system for chemical recycling research and development tasks for mixed plastic waste. The main research areas of the Chemical Technology Laboratory (LCT) at Ghent University are chemical reaction engineering and chemical reaction kinetics.
Coperion has specially designed a laboratory system based on the ZSK 18 MEGAlab twin-screw extruder dedicated to the chemical recovery of post-consumer recycled (PCR) plastics with a throughput of 1-10 kg per hour. In addition to the extruder, it includes a feeder from Coperion K-Tron as well as a vacuum unit.
The Coperion ZSK twin screw extruder is part of a new plant for chemical recycling at Ghent University. It is connected to an eddy current reactor, and molten plastic can flow directly into the reactor as shown in the figure.
Coperion says its twin-screw extruder technology is particularly suitable for the chemical recycling of PCR plastics. After the PCR plastic (crushing or compaction) reaches the process section of the extruder, a large amount of mechanical energy is introduced into the PCR plastic in a short time due to the intensive dispersion and shearing of the twin screw. Within about 30 seconds, the plastic is highly homogenized to remove volatile components and melt temperatures up to 350°C. Under certain conditions, even the vacuum system of the extruder can completely remove residual moisture or trace chlorides from PVC.
Inside the reactor, the melt is further heated. The polymer undergoes pyrolysis in an oxygen-free environment up to 500 °C, splitting into shorter units. At the same time, due to the chain reaction initiated, the polymer is cracked into a hydrocarbon mixture. These mixtures are further converted into monomers, petrochemical feedstocks or syngas, which are then further processed by distillation into marketable products such as petroleum, heavy fuels or waxes.
In actual scenarios, chemical recovery often requires the addition of catalysts, and insufficient purity and cleanliness of raw materials will have different degrees of negative impact on the catalytic effect of catalysts. Through its own R&D and innovation, Ningbo Jianfeng New Materials Co., Ltd. can provide a series of high-quality waste plastics with high purity and low impurity content for chemical recycling, including but not limited to PET, PA, PP, PE, PS.
Note: Quoted from Research Progress on Chemical Recycling and Resource Utilization of Waste Plastics, Sun Xiaodong; AMI《PLASTICS RECYCLING WORLD》
Translation: Neo
