What is Gasoline Polyethylene?

2026-04-28

The Traditional Production Methods of Gasoline Polyethylene

For waste polyethylene plastic with large amounts of polyolefin and difficult to convert, current conversion strategies mainly rely on high reaction temperatures (above 400 ℃), precious metal catalysts, and external hydrogen sources, thereby reducing the industrial potential of polyolefin chemical recovery. The low-cost and low-energy conversion of polyolefins has always been one of the challenges in the field of plastic conversion.

Gasoline Polyethylene New Strategy: Inspiration from Hydrocracking

Catalytic Conversion of Waste Polyethylene Plastics to Gasoline.The image is sourced from reference one

The scientific research team of the Institute of Chemistry of the Chinese Academy of Sciences successfully transformed polyethylene plastics into high-quality gasoline at low temperature (240°C) without a noble metal catalyst and hydrogen source. The gasoline yield exceeded 80%, and the selectivity reached 99%. The team used molecular sieves with layered self-supporting structures (LSP) for catalytic conversion of polyolefins. Due to the abundant mesoporous channels and external specific surface area of LSP molecular sieves, they can fully contact polyolefins and efficiently catalyze polymer chain breakage. It is worth noting that the layered structure makes LSP more abundant in Q2 and Q3 silicon species than conventional molecular sieves, and it also has stronger Lewis acid sites. The adsorbed pyridine molecules still cannot desorb at 450 ℃.

Through 31P NMR of organic phosphine probe molecule adsorption, researchers found that the super Lewis acid site of LSP molecular sieve is a unique framework triple coordinated aluminum (oFTAl) site. The presence of the oFTAl site can accelerate the H/D exchange between deuterated n-hexane and non deuterated isopentane, indicating that this site can accelerate the activation of polyolefin molecular chains, promote hydrogen transfer reactions, efficiently catalyze the aromatization of some polyolefins, and provide hydrogen for the generated olefins, thereby producing gasoline components mainly composed of alkanes under the condition of no external hydrogen source.

Finally, the researchers studied the complete pathway of polyethylene conversion through inelastic neutron scattering. Firstly, the Brønsted acid sites and OFTAL sites of LSP molecular sieve jointly activate the C-H bonds of polyethylene and generate carbocations. Then, polyethylene undergoes beta cracking and isomerization to produce short chain isomers, while another part of the polyethylene chain undergoes aromatization to produce hydrogen. Finally, the isomers are hydrogenated and converted into isomers through a hydrogen transfer reaction, forming gasoline products mainly composed of isomers.

Reference: Cen, Z., Han, X., Lin, L. et al. Upcycling of polyethylene to gasoline through a self-supplied hydrogen strategy in a layered self-pillared zeolite [J]. Nature Chemistry, 2024.

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