Wong S.L., Armenise S., Lee C.H., Wong K.Y., Tan H., Nyakuma B.B., Muñoz M., 2024, Inductively Heated Plastic Pyrolysis over H-ZSM5 Zeolite and Fluid Catalytic Cracking Catalyst, Chemical Engineering Transactions, 113, 91-96.
The shift from a linear to a circular economy is an important step in combating global plastic pollution. Pyrolysis is a vital component of the circular economy, transforming unrecyclable plastic waste into valuable resources. However, plastic pyrolysis is an endothermic process with technical challenges due to its high energy demand that could potentially reduce its economic viability. To address this challenge, this study investigates the inductively heated thermal and catalytic pyrolysis of virgin plastics like high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS) pellets and postconsumer plastic waste (PW) in a stainless-steel fixed bed reactor at 400-700°C. HZSM-5 zeolite and fluid catalytic cracking catalysts were employed as catalysts. All virgin plastics underwent complete plastic conversion, with PE and PP producing heavy hydrocarbons and PS generating high styrene yields through thermal pyrolysis. Catalytic pyrolysis over ZSM-5 catalyst notably increased gas yields for PE and PP due to enhanced cracking of pyrolysis intermediates. ZSM-5 significantly altered the liquid composition of PS pyrolysis by hydrogenating and isomerizing aliphatic chains on styrene molecules, despite having a minor impact on liquid yield. Despite the high char yield (25%) from PW, the permanent gases and gasoline exceeded virgin plastics due to the fluffy nature of PW samples, which enhanced transfer phenomena during pyrolysis. This study provides comprehensive mass balances for both thermal and catalytic pyrolysis of virgin and waste plastics, offering further insights into the role of pyrolysis in achieving a net-zero circular plastics economy.
