Enhancing aromatics yield by zeolites in polypropylene hydrocracking to jet fuel over Ru1-ZrO2 without forming CH4

Abstract

Hydrocracking of polyolefin plastics into jet-fuel-range hydrocarbons presents a promising route for plastic upcycling. Here, we report a Ru1-ZrO2 + ZSM-5 catalyst that enables selective hydrocracking of polypropylene (PP) into aromatics-enriched jet-fuel-range hydrocarbons under mild conditions. Compared to Ru1–ZrO2 alone, the Ru1-ZrO2 + ZSM-5 catalyst increases PP conversion from 47% to 82%, liquid yield from 33% to 63%, and aromatics yield from 1 wt% to 13 wt%, with negligible low-value methane formation. A thorough study of Brønsted acid site (BAS) impact on the reaction, including employing model molecule, i.e., squalane, indicates that increasing the BAS density of ZSM-5 is more effective than simply adding more ZSM-5 in enhancing conversion and aromatics production, while neither approach promotes CH4 formation. This strategy of leveraging zeolites with high BAS density can be extended to other bifunctional catalysts to improve aromatic yields without sacrificing fuel quality.