(532x) Advances in Plastic Recycling: Intrinsic Kinetics of Polypropylene Pyrolysis from Pulse-Heated Analysis of Solid Reactions (PHASR)

Global plastic production has undergone rapid growth in recent years, owing to the continual increase in demand for polymeric materials in modern life. The demand for and production of plastics has resulted in the generation of billions of tons of plastic waste, most of which has been discarded in landfills or the environment. To address this growing plastic waste challenge, new recycling techniques must be developed to enable a circular plastic economy wherein end-of-life plastics are recycled in a closed loop, regenerating the original polymers with complete fidelity. Pyrolysis, the thermal degradation of a material in an inert atmosphere, is a promising technique for establishing a circular plastic economy. To develop efficient industrial pyrolysis reactors, the intrinsic kinetics of plastic pyrolysis must be quantified. This remains an ongoing challenge, due to the complex nature of pyrolysis mechanisms and limitations of standard analytical techniques.

To meet this need, the novel ‘pulse-heated analysis of solid reactions’ (PHASR) reactor system, originally developed for cellulose pyrolysis, has been redesigned for polyolefin pyrolysis and utilized to study polypropylene pyrolysis. The PHASR reactor is uniquely able to operate absent transport limitations, secondary reactions, or kinetic measurement limitations to measure intrinsic kinetics on the millisecond scale at temperatures up to 700 °C. [1] In this work, we demonstrate the capability of the PHASR reactor to pyrolyze polypropylene under isothermal, kinetically limited conditions, presenting yield vs. reaction time data and intrinsic lumped kinetics. [2] A second Visual PHASR system was developed, which enables the direct observation of pyrolysis experiments via high speed photography. [1] Visual analysis of polypropylene pyrolysis reveals reaction phenomena and results are compared to experimental data. [2] Insights into polypropylene pyrolysis from the PHASR reactor systems will help to promote a circular plastic economy.

References:

[1] ChemSusChem, 2021, 14 (19), 4214-4227.

[2] In Preparation, 2022.