Kinetic and mechanism of Tarfaya (Morocco) oil shale and LDPE mixture pyrolysis

A kinetic study of the pyrolysis of oil shale mixed with LDPE was carried out by thermogravimetric analysis (TGA). Different runs were performed at heating rates between 2 and 50 K min−1. The results obtained from this comprehensive investigation indicated that they are three main degradation steps and the increase in the heating rate caused a lateral shift in the thermograms. The difference of weight loss (Δw) between experimental and theoretical, calculated as algebraic sums of the mixture for different heating rates of 2, 10, 20 and 50 K min−1, is about 8–11% at 670–840 K. These experimental results indicate a significant synergistic effect during pyrolysis of oil shale mixed with LDPE. Kissinger–Akahira–Sunose method, Friedman's method, Flynn–Wall–Ozawa method and Coats–Redfern have been used to determine the activation energies of materials degradation. The analyses of the processes mechanism of materials by Criado et al. method and Coats–Redfern method showed: the most probable model for the pyrolysis process of oil shale kerogen agrees with diffusion model (D4 mechanism); and the thermal degradation process of LDPE goes to a mechanism involving “Contracting cylinder” model (R2 mechanism), whereas the mixture degrades following a kinetic model of D4.