(576e) Progress Towards to a Circular Plastic Economy: Intrinsic Kinetics of Polypropylene Pyrolysis Via Pulse-Heated Analysis of Solid Reactions (PHASR)

Polymeric materials have become ubiquitous in modern life, as evidence by the rapid and continual growth in global plastic production. Consequently, billions of tons of plastic waste have been produced which are insufficiently managed under the current linear plastic economy wherein the majority of plastic waste has been discarded in landfills or the environment. A material of principal importance is polypropylene, one of the most widely produced thermoplastic materials, accounting for approximately 20% of global polymer production. Under a circular plastic economy, end-of-life plastics are instead recycled in a closed loop, fully regenerating the original polymers. To realize a circular plastic economy, new recycling techniques must be developed. Pyrolysis, the thermal degradation of a material in an inert atmosphere, has high potential as a driving technology for a circular plastic economy. Quantification of the intrinsic kinetics of plastic pyrolysis is an ongoing a challenge, owing to the complexity of the pyrolysis mechanisms and limitations of standard analytical methods.

In this work, the novel ‘pulse-heated analysis of solid reactions’ (PHASR) reactor system has been utilized to study polypropylene pyrolysis. The PHASR reactor, originally developed for cellulose pyrolysis and redesigned for polyolefin pyrolysis, is uniquely capable of operating absent transport limitations, secondary reactions, or kinetic measurement limitations to measure intrinsic kinetics on the millisecond scale at temperatures up to 700 °C. [1] The abilities of the PHASR reactor to pyrolyze polypropylene under isothermal, kinetically limited conditions are demonstrated in this work and yield vs. reaction time data and intrinsic lumped kinetics are presented. [2] In addition, visual analysis of polypropylene pyrolysis was performed using a Visual PHASR experimental system, which allows for direct observation of pyrolysis reactions via high speed photography. Visualization results reveal reaction phenomena and are compared to experimental results. [2] The data from the PHASR reactor systems provides new insights that will help to enable the design and development of more efficient industrial pyrolysis reactors and ultimately a circular plastic economy.

References:

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

[2] In Preparation, 2022.