Towards a lumped approach for solid plastic waste gasification: Polyethylene and polypropylene pyrolysis

Area of Science:

• Chemical Engineering
• Materials Science
• Thermodynamics

Background:

• Solid plastic waste (SPW) presents environmental challenges but offers potential resources for a circular economy.
• Thermochemical conversion technologies like pyrolysis are key to valorizing SPW into chemicals and fuels.
• Accurate kinetic modeling of polymer pyrolysis is essential for optimizing these processes.

Purpose of the Study:

• To develop a semi-detailed kinetic model for polyethylene (PE) and polypropylene (PP) pyrolysis.
• To enable consistent modeling of polymer mixtures by adapting the functional group approach.
• To provide a computationally efficient model for supporting the design of SPW thermochemical recycling.

Main Methods:

• A functional group approach was employed, distinguishing High Molecular Weight and Low Molecular Weight species.
• Validated lumping techniques were used to reduce computational cost.
• The model was validated against experimental data for mass loss and product distribution.

Main Results:

• A semi-detailed kinetic model was developed, comprising 74 species for PE and 126 species for PP.
• The model accurately predicts mass-loss and product distribution profiles.
• The approach demonstrates comparable accuracy to more complex detailed models.

Conclusions:

• The proposed kinetic model is a valuable tool for the thermochemical recycling of PE and PP.
• The functional group approach is extendable to other polymers and can be integrated into existing kinetic frameworks (e.g., CRECK).
• This work facilitates the understanding of mixture interactions and secondary reactions in plastic waste conversion.