Comparative study on properties of waste tyre pyrolysis oil and its distillates obtained by molecular distillation

Pyrolysis offers significant advantages for the resourceful recycling of waste tyre (WT), while molecular distillation can efficiently separate and non-destructively collect the resulting pyrolysis oil for high-value utilisation of different oil fractions. Herein, WT was pyrolysed at various temperatures (350 °C, 400 °C, 450 °C and 500 °C) to obtain the desired pyrolysis products. The optimal pyrolysis temperature of 400 °C was selected based on the analysis of WT pyrolysis at temperatures ranging from 350 °C to 500 °C. Subsequently, molecular distillation experiments were conducted on the waste tyre pyrolysis oil (WTPO) obtained at 400 °C. The distillation process was carried out at varying temperatures (100 °C, 115 °C, 130 °C, 145 °C and 160 °C) to separate the WTPO into light oil (LO) and heavy oil (HO), including LO 130 °C (LO obtained at 130 °C) and HO 130 °C (HO obtained at 130 °C). The characteristics of the pyrolysis products and WTPO fractions were investigated, with a focus on the effect of temperature on the yield and composition distribution of the pyrolysis products as well as the distribution pattern of WTPO fractions. The maximum pyrolysis oil output was obtained at 400 °C (58.23 wt%), with a high proportion of alkane (9.42 %) and aromatics (75.07 %). LO 130 °C contained more olefins (16.55 %) and ketones (7.37 %) than HO 130 °C , whereas HO 130 °C had more alkanes (5.65 %) and aromatic hydrocarbons (61.99 %). The findings of this study suggest the effectiveness of using molecular distillation to separate WTPO fractions. • Waste tyre pyrolysis oil (WTPO) was separated into light oil (LO) and heavy oil (HO) by molecular distillation. • The vacuum degree is low (120 Pa) and the fractionation temperature is wide (100–160 °C) in the process of molecular distillation. • Each LO showed obviously higher olefins and ketones containing, while the corresponding HO higher alkanes and aromatic hydrocarbons containing. • Higher molecular distillation temperatures conduce to further separate WTPO fractions.