Suppressing Hydrogen Transfer and Aromatization Reactions Enables Efficient Photothermal Recycling of Polyethylene into Platform Olefins.

Miao, Yingxuan; Qian, Xi; Wang, Jinhu; Kang, Lei; Jiang, Chaoran; Lin, Zheshuai; Wu, Li-Zhu; Zhao, Yunxuan et al. · Adv Mater · 2026

basic_science · Level V

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Abstract

The recycling of polyethylene (PE) into highly selective platform olefins holds great promise as a potential closed-loop recycling route that minimizes dependence on the petrochemical industries, whereas the selectivity of olefins is mainly limited by two side reactions: hydrogen transfer and aromatization. Herein, we present a photothermal recycling pathway that effectively converts various types of PE into highly selective olefins using ZnCrO<sub>x</sub>/HZSM-5 composite catalyst, with efficaciously suppressing both side reactions. The inclusion of ZnCrO<sub>x</sub> modifies catalyst acidity to inhibit the hydrogen transfer reaction, while jointly establishing an intra-catalyst spatial temperature gradient through distinct photothermal responses between ZnCrO<sub>x</sub> and HZSM-5 whereby the endothermic aromatization can be suppressed. This strategy achieves an impressive selectivity of 75.4% for C<sub>2</sub>-C<sub>5</sub> hydrocarbons, with 84.7% of them being C<sub>2</sub>-C<sub>5</sub> olefins, in the photothermal recycling of low-density PE (LDPE) under atmospheric pressure using Xe lamp irradiation. Further, the demonstrated universality across various PE feedstocks (e.g., high-density PE and commercial LDPE bags) and concentrated sunlight operation highlights a solar-powered plastic-to-olefin platform with industrial viability.