Conversion of polyethylene to monoaromatics via a tandem catalytic strategy.

The catalytic conversion of polyethylene (PE) waste into high-value aromatics, particularly benzene-toluene-xylene (BTX), remains a challenge in chemical recycling. We present a tandem two-stage fixed-bed system that efficiently converts PE into BTX without requiring noble-metal catalysts or external hydrogen acceptors. The process achieves an aromatics yield of 59.9%, including a BTX yield of 51.5%, which represents 86% of the total aromatics produced. In the first stage, PE undergoes near-complete catalytic cracking over a layered self-pillared zeolite (LSP-Z100). The second stage employs a dual-catalyst configuration where Ga/LSP-Z100 promotes aromatization of cracking intermediates, while Co/LSP-Z100 adsorbs small alkanes, catalyzes their dehydrogenation to olefins, and cleaves low-value polycyclic aromatic hydrocarbons to enhance BTX production. The catalyst maintains stable performance over five consecutive cycles and yields approximately 55% aromatics from real plastic waste. This tandem catalytic strategy offers a highly effective and sustainable route for the valorization of PE waste into high-value aromatic chemicals.