Aromatics production via PET pyrolysis enhanced by LDPE hydrogen transfer over MGS catalyst: Experimental and theoretical calculations

Hydrodeoxygenation of waste polyethylene terephthalate (PET) presents a promising avenue for aromatic production; however, achieving complete deoxygenation alongside high aromatic relative peak area abundance remains a significant challenge. Herein, we demonstrate a novel one-pot coupled pyrolysis process for waste PET and LDPE using a Mesoporous Granular Stacked Zeolite Catalyst (MGS), achieving a greater than 99% aromatic relative peak area abundance in product oil. Comprehensive experiments and characterization reveal that this outstanding catalytic performance stems from the MGS catalyst's exceptionally large specific surface area, abundant mesoporosity, and superior hydrogen transfer capability. Mechanistic investigations employing Density Functional Theory (DFT) elucidate the hydrogen transfer pathway: under the influence of oxygen and aluminium sites within the MGS framework, LDPE undergoes dehydrogenation and cyclization, while activated hydrogen species drive the catalytic pyrolysis of PET. Remarkably, the catalyst exhibits exceptional stability over multiple recycling cycles. This work establishes a promising and sustainable strategy for the chemical recycling of PET and LDPE and provides fundamental mechanistic insights for designing advanced catalysts for hydrogen transfer reactions.