Cleavage Alkylation Coupling with Versatile Amide-Based Eutectic Catalytic Systems

This study introduces amide-based eutectic solvents (ESs) as a versatile and high-efficiency catalytic system for converting polyolefin waste into liquid alkanes in coupled cracking-alkylation. Owing to the rich variety of molecular active species (i.e., [AlCl₃(Acetamide)n] and AlCl₃) and ionic active species (i.e., [Al₂Cl₇]⁻ and [AlCl₂(Acetamide)n]⁺) present in the catalytic system, carbocation intermediates can be stably generated, thereby facilitating hydride transfer and cleaving polyethylene C-C bonds during the cracking cycle. For the first time, we establish a direct and quantitative correlation between Al species diversity and carbocation concentration, validated by Et₃SiH chemical trapping combined with multinuclear NMR and operando IR spectroscopy. We demonstrate tunable selectivity to either light gasoline (C₄-C₁₀) or aviation kerosene (C₇-C₁₈) with isopentane or isopentene as alkylation reactants. Time-resolved product analysis together with isotopic labeling clearly confirms that aviation kerosene-range hydrocarbons (C₇-C₁₈) are primarily derived from polyethylene fragments and chain-extended by iC₅⁼ alkylation. Ab initio molecular dynamics simulations reveal that cooperative dissociation of diverse Al species sustains a stable tert-butyl and chloromethyl carbocations population, rationalizing the superior catalytic efficiency of Acetamide-1.5AlCl₃. These advances provide both mechanistic clarity and a broadly applicable strategy for selective production of gasoline- and kerosene-range hydrocarbons from plastic waste, offering new opportunities for premium-grade fuel generation.