Abstract
Catalytic pyrolysis of waste plastics using iron-based metal-acid catalysts is a promising waste-to-energy technology to deliver clean renewable fuels. While these catalysts show valid catalytic activity during pyrolysis, their ability to guide tandem reactions over metal and acid sites remains uncertain. In this study, we employ the Fe2O3/USY catalysts to recycle polyethylene (PE) into liquid fuels, and demonstrate the tandem catalysis of the Fe2O3/USY catalysts during PE depolymerization. The highest fuel oil yield obtained was 78.1 % after Fe2O3/USY catalysis (5 % Fe loading, Si/Al ratio = 80). The resulting oil predominantly falls within the gasoline range, with a carbon number distribution rich in C5–C9 range. The oil composition comprises 71.3 % olefins and 16.7 % paraffins, mostly isomeric, while few aromatics were obtained. Comparative experiments confirm that PE depolymerization over the metal and acid sites of Fe2O3/USY catalysts involves an olefin-intermediate tandem pathway: the Fe2O3 enhances olefin-intermediate generation through its dehydrogenation activity, while the USY allows these olefin-intermediates to undergo further cleavage over the acid sites. Although the Fe2O3 loading on USY enhances PE cracking by facilitating olefin-intermediate generation in tandem catalysis, the reduced acidity inhibits PE cracking. Therefore, when aiming for oil production via PE pyrolysis, the delicate balance between reduced acidity and increased dehydrogenation activity after Fe2O3 loading must be taken into account.
Published Version
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