Synthesis of gasoline and jet fuel range cycloalkanes and aromatics from poly(ethylene terephthalate) waste

Abstract

For the first time, gasoline and jet fuel range C₇–C₈ cycloalkanes and aromatics were selectively synthesized by the alcoholysis of poly(ethylene terephthalate) (PET) waste, followed by solvent-free hydrogenation and hydrodeoxygenation (HDO). It was found that methanol is highly reactive for the alcoholysis of PET waste. In the absence of any catalyst, a high yield of dimethyl terephthalate (97.3%) was achieved under mild conditions (473 K, 3.5 h). Dimethyl terephthalate exists as a solid and can be automatically separated from methanol with a decrease in temperature. Subsequently, dimethyl terephthalate was liquefied to dimethyl cyclohexane-1,4-dicarboxylate by hydrogenation over noble metal catalysts. Among the investigated catalysts, Pt/C exhibited the highest activity. Finally, the dimethyl cyclohexane-1,4-dicarboxylate as obtained was further hydrodeoxygenated to C₇–C₈ cycloalkanes and aromatics that can be used as gasoline or additives to improve the densities (or volumetric heat value) and sealabilities of current bio-jet fuels. Bimetallic Ru–Cu/SiO₂ was found to be a promising HDO catalyst. According to the characterization results, the excellent HDO performance of Ru–Cu/SiO₂ can be explained by the formation of smaller Ru–Cu alloy particles during the catalyst preparation. In real applications, dimethyl cyclohexane-1,4-dicarboxylate can also be simultaneously hydrodeoxygenated with biomass derived oxygenates to produce jet fuel with a suitable content of cycloalkanes and aromatics.