(154g) Waste Plastics Valorization through Pyrolysis Processes: A System Analysis Framework

Plastic waste disposal has caused significant environmental problems. Chemical recycling is a promising solution to complement mechanical recycling, with fast pyrolysis being an effective method to handle hard-to-recycle plastics while producing valuable products such as oil, waxes, and aromatics. This study focuses on designing and simulating an open-loop recycling process for waste polypropylene (PP) through fast pyrolysis to evaluate its economic and environmental performances.

The reactor was designed to operate at 510 ℃, optimizing the production of paraffin waxes and suppressing the formation of liquid petroleum gas (LPG) and aromatics. The subsequent produced waxes were further cracked using a fluid catalytic cracking (FCC) reactor in a second fluidized bed reactor, followed by three distillation columns to separate product streams and produce 99% purity gasoline and diesel. Techno-economic analysis and life-cycle assessment were conducted to evaluate the economic feasibility and environmental implications of the proposed technology, and sensitivity analysis on important process parameters was performed to obtain the optimum plant design conditions.

The results indicated that the conversion of waste PP into liquid fuels using fast pyrolysis is a sustainable and economically feasible approach that can help reduce plastic waste pollution, oil usage, and carbon dioxide emissions, achieving circular economy objectives. In conclusion, this study demonstrates the potential of fast pyrolysis as a sustainable approach to complement mechanical recycling and facilitate the transition towards a circular economy for plastic waste.