Plastic Devolatilisation Kinetics During Isothermal High-Temperature Pyrolysis: Focus on Solid Products (Part I).

Area of Science:

• Chemical Engineering
• Materials Science
• Environmental Science

Background:

• Incineration is the primary method for plastic packaging waste in Europe.
• Mechanical recycling faces limitations, necessitating advanced waste treatment solutions.
• Sustainable thermochemical conversion offers a promising alternative.

Purpose of the Study:

• To investigate the thermochemical conversion of plastic waste via high-temperature flash pyrolysis.
• To analyze the kinetics and yields of the devolatilization stage.
• To explore the potential for producing carbon black precursors.

Main Methods:

• Flash pyrolysis of polypropylene, polystyrene, and mixed municipal plastic packaging.
• Experiments conducted in a pressurized wire mesh reactor.
• Varied temperature (600-1200 °C), residence time (0.5-10 s), and pressure (1-25 bar).

Main Results:

• Devolatilization completed within 5 seconds at 800-1200 °C.
• Volatile yield increased with temperature up to 2-5 seconds.
• Pressure was a kinetic limitation below 800 °C but not at higher temperatures.
• Pyrolytic carbon exhibited structural similarity to industrial carbon black.

Conclusions:

• High-temperature flash pyrolysis is effective for plastic waste conversion.
• Optimized conditions yield valuable volatile organic compounds for carbon black.
• Kinetic data supports the design of scaled-up pyrolysis reactors.