Production of aromatic hydrocarbons by hydro-liquefaction of high-density polyethylene (HDPE) over Ni/HZSM-5

Abstract HDPE hydro-liquefaction to produce aromatics was studied by optimizing reaction parameters. Ni loading (0–20 wt%), reaction temperature (360–420 °C), catalyst to reactant ratio (0.02-0.08) and reaction time (0–4 h) were investigated using Ni/HZSM-5 catalyst. The maximum aromatic yield (28.9%) was obtained over 15 wt% Ni/HZSM-5 at 400 ℃ for 1 h and using catalyst to reactant ratio of 0.06. GC–MS analysis showed that mono-ring aromatics were enriched, with xylene having the highest selectivity (20.4–27.3%). The effects of parameters on product distribution were further studied. Both high Ni loading, high temperature and high catalyst to reactant ratio gave rise to the formation of other C10-C12 benzene. Xylene was easily formed at the reaction temperature of 380 °C and catalyst to reactant ratio of 0.04. The primary reaction competing with aromatic hydrocarbon production was the cracking of liquid hydrocarbons to produce gas. A possible reaction pathway was also proposed to clarify the overall hydro-liquefaction of HDPE for aromatic hydrocarbons.