(642f) Plastic Waste Upgrade to Olefins Via Microwave Pyrolysis over Mesoporous Solid Acids

Catalytic pyrolysis is a very promising chemical upcycling approach as it is feedstock agnostic. However, its high energy demand can lead to significant carbon dioxide production. While light olefins (C₂-C₄) have been produced, the selectivity to larger olefins (>C₄; valued at $ 1700 Mt^-1), chemical industry's building blocks for lubricants, surfactants, plasticizers, etc., is usually very low. Larger olefins are typically made from smaller ones and their direct production from plastic waste can fill in a significant market gap but this has seldomly been done so far. In this work, we demonstrate a single-pot, microwave (MW) - slurry catalytic reactor to selectively convert Low-density Polyethylene (LDPE) to medium-sized olefins in seconds at low reaction temperatures. The solid acid catalyst profoundly controls the selectivity to olefins. We systematically investigate the influence of catalyst acidity, nature of acid sites and porosity on the catalytic deconstruction of LDPE and provide insights onto depolymerization chemistry. We also demonstrate that the MW outperforms conventional heating (CH) pyrolysis by reducing coke and the slurry enables enhanced transport to increase effective rates and reduce reaction times. Technoeconomic analysis and life cycle assessment were performed to demonstrate the potential of the technology.