Two-stage thermocatalytic conversion of waste XLPE to diesel-like fuel

Abstract

Cross-linked polyethylenes (XLPE) are not preferred in industrial pyrolysis applications and mechanical recovery methods due to great thermochemical resistance to heat and deformation. The studies on pyrolysis of XLPE up to 600°C on obtaining fuel have generally yielded high levels of wax and have not been of interest to the energy sector. In this study, two-stage pyrolysis of XLPE was carried out catalytically and also without catalyst (thermal, T- -pyr) under 500°C with heating rates of 5 and 10°C min-1. In the pyrolysis experiments, three different catalytic studies were performed by adding MCM- -41 + HZSM-5 catalyst mixture to the polymer phase only (PPC-pyr), by filling Cu(I)-MAS + HZSM-5 catalyst mixture to the gas outlet column only (GPC- -Pyr) and adding catalyst mixtures in both polymer phase and gas phase (MPC- -pyr). The highest diesel-like fuel (91.40 wt. %) was obtained in multiphase catalytic pyrolysis experiments at 460°C with a heating rate of 5°C min-1. The calorific value, kinematic viscosity, density, flash point and cetane number of the fuel were found as 45.97 MJ kg-1, 2.72 cSt, 832.5 kg m-3, 57 and 59°C, respectively. The results of the two-stage catalytic cracking and the heating rate profile will be a guide for industrial pyrolysis applications. The simple feasibility for industrial applications showed that it would be a very profitable investment.

Keywords

• cross-linked polyethylene
• thermal cracking
• heterogene catalysis
• zeolite