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

Pyrolysis is a technology capable of harnessing energy from challenging-to-recycle plastics, thus mitigating the necessity for incineration or landfill disposal. To optimize the plastic pyrolysis process, reliable models for product yield prediction are imperative. This study endeavors to determine the suitability of lumped models, a widely used approach for modeling biomass and coal pyrolysis, in accurately estimating product yields in the context of plastic pyrolysis. To address this question, three lumped models with parallel and competitive reaction mechanisms were compared and fitted to experimental data collected across a broad temperature range. The aim is to identify which models can elucidate the most appropriate reaction pathway for the plastic pyrolysis process. The first model in this study assesses whether the commonly employed wood pyrolysis kinetic models can effectively fit the experimental data from plastic pyrolysis. Subsequently, the final two models introduce additional reactions into the pyrolysis process, prompting the authors to investigate the necessity of these supplementary reaction pathways for accurately predicting plastic pyrolysis outcomes. This investigation seeks to pinpoint the essential terms and discern which ones may be safely omitted from the models. The results of the study reveal that the model incorporating secondary tar reactions with gas, tar, and char is the most precise in predicting the products of plastic pyrolysis, surpassing all other combinations evaluated in this research.