Microwave-Catalyzed Selective Upcycling of Single-Use Polyethylene Films to Light Olefins
2025 AIChE Annual Meeting
Microwave-Catalyzed Selective Upcycling of Single-Use Polyethylene Films to Light Olefins
There has been a global increase in the production of single-use polyethylene (PE) films, accompanied by a disproportionate rise in the management of the plastic waste and pollution it generates. The conventional and widely used method of mechanical recycling of PE is inefficient, with many drawbacks, from polymer degradation to the limited reuse potential of recycled products. Other recycling techniques, such as thermochemical methods like pyrolysis, require high amounts of energy and yield low-value product materials. This study employs a new strategy to upcycle low-density polyethylene (LDPE) films using a microwave-assisted catalytic approach. This approach allows for the selective upcycling of PE films into valuable light olefins such as ethene, propene, and butene. The catalyst that was used throughout the experiment was a ruthenium-supported iron oxide (Ru/Fe2O3). This catalyst was found to have high microwave absorption and catalytic activity. It rapidly heated the PE catalyst mixture, performing with a uniform temperature distribution, which assisted with reactions between the polymer and catalyst. The localized heating increased energy efficiency, accelerated reaction kinetics, and promoted selective C-C bond cleavage, significantly increasing light olefin yields and minimizing byproducts like char and heavy hydrocarbons.
Experimental conditions were optimized by controlling parameters such as temperature ramping rate, reaction temperature (generally maintained at 400°C), inert gas flow rate, catalyst to polymer ratios, and polymer particle size. Characterization techniques such as thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area measurements, X-ray diffraction (XRD), and temperature-programmed desorption (TPD) confirmed catalyst stability and activity throughout the process. The microwave-catalyst system was found to have 12% higher selectivity rates and conversion rates compared to the conventional thermal recycling methods. This highlights the potential for microwave catalyst upcycling as a more energy-efficient recycling method with the added benefit of plastic waste valorization through the generation of olefins. This approach addresses the environmental challenges posed by plastic waste accumulation and also contributes to a circular economy of plastic by converting low-value plastics into high-demand chemical feedstocks.
