A Study of Parallel and Competitive Reaction Schemes in Kinetic Modeling of Plastic Pyrolysis

Area of Science:

• Chemical Engineering
• Materials Science
• Environmental Science

Background:

• Pyrolysis offers an alternative to landfilling and incineration for challenging plastics.
• Accurate product yield prediction is crucial for optimizing plastic pyrolysis.
• Lumped models are common for biomass and coal pyrolysis but their plastic pyrolysis applicability is less understood.

Purpose of the Study:

• To evaluate the suitability of lumped models for plastic pyrolysis product yield prediction.
• To compare three lumped models with varying reaction mechanisms.
• To identify the most accurate kinetic model for plastic pyrolysis.

Main Methods:

• Fitted three lumped kinetic models with parallel and competitive reaction mechanisms to experimental data.
• Compared model performance across a wide temperature range.
• Assessed the necessity of secondary reactions for accurate yield prediction.

Main Results:

• The model incorporating secondary tar reactions with gas, tar, and char provided the most precise product yield predictions.
• This comprehensive model outperformed simpler kinetic models derived from wood pyrolysis.
• The study identified essential kinetic terms and those that could be omitted.

Conclusions:

• Lumped models are suitable for plastic pyrolysis, but require specific reaction pathways.
• Including secondary tar reactions significantly enhances prediction accuracy.
• The validated model provides a reliable tool for optimizing plastic pyrolysis processes.