AlCl3–Assisted Mechanochemical Transformation of Polyethylene into C7–C15 Liquid Hydrocarbons

Abstract

The transformation of polyethylene (PE) into recoverable liquid hydrocarbons under solvent-free conditions without external heating remains challenging. Here, we report an AlCl3-assisted mechanochemical approach that produces a liquid hydrocarbon fraction concentrated in the C7–C15 range. Under the selected conditions, the gravimetrically determined extent of PE degradation was approximately 97%, whereas the yield of CH2Cl2-soluble, GC-detectable hydrocarbons was approximately 62 wt % relative to the initial PE mass. These values describe different aspects of the process; the latter does not represent total product yield. The stainless-steel and ZrO2 milling assemblies gave different product distributions, with greater contributions from lower-carbon-number and olefin-associated products in the stainless-steel assembly and from higher-carbon-number and monoaromatic-assigned components in the ZrO2 assembly. GC–MS, GC × GC–TOFMS, and NMR identified olefinic, cyclic, and monoaromatic structures in the recovered fraction. Time-resolved analysis showed a shift from higher- to lower-carbon-number products during milling. SEC, trapping, rearrangement-probe, and model-substrate experiments are consistent with mechanically induced chain scission involving radical processes and AlCl3-assisted secondary transformation. The trapping and rearrangement results also provide indirect evidence compatible with transient electrophilic intermediates, although the elementary pathway and temporal sequence remain unresolved. This study demonstrates liquid-hydrocarbon formation from PE under Lewis-acid-assisted mechanochemical conditions.