Coking-Resistant Polyethylene Upcycling Modulated by Zeolite Micropore Diffusion

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Plastic waste, particularly polyethylene, poses a significant global environmental challenge.
• Current plastic recycling methods often require high temperatures and are energy-intensive.
• Efficient conversion of polyethylene into valuable chemicals is crucial for sustainable waste management.

Purpose of the Study:

• To develop a low-temperature catalytic process for converting polyethylene into light olefins.
• To investigate the role of ZSM-5 zeolite nanosheets in enhancing polyethylene depolymerization.
• To demonstrate a coking-resistant and industrially viable method for plastic waste upcycling.

Main Methods:

• Polyethylene was catalytically cracked at 280 °C using ZSM-5 zeolite nanosheets in a hydrogen atmosphere.
• The reaction mechanism involving melting, diffusion, and cracking on zeolite surfaces and within micropores was analyzed.
• The efficiency of the process was tested on both model polyethylene and polyethylene-rich plastic wastes.

Main Results:

• Up to 74.6% yield of light hydrocarbons (C1-C7) was achieved, with 83.9% being valuable C3-C6 olefins.
• Minimal coke formation was observed due to enhanced intermediate diffusion and hydrogen participation.
• The process demonstrated high efficiency for various polyethylene-rich plastic wastes.

Conclusions:

• ZSM-5 zeolite nanosheets enable efficient, low-temperature polyethylene conversion into olefins with suppressed coke formation.
• The catalytic system offers a coking-resistant and viable pathway for upcycling plastic waste into valuable chemicals.
• This approach provides an industrially and economically feasible solution for addressing plastic pollution.