Co-pyrolysis of polyolefin mixtures and oil palm fibre for the production of liquid fuel: kinetics and thermodynamic study

Studies on the co-pyrolysis of plastic waste and biomass to obtain sustainable liquid fuel, while reducing the amount of unwanted plastics and agricultural solid residues, have gained global attention recently. The purpose of this work was to investigate the thermal, kinetics, and thermodynamic events that occurred during the pyrolysis of binary polyolefin (PO) mixture, oil palm fibre (OPF), and their blends (ternary mixtures) at 5, 10, 15, and 20 degrees C/min using a thermogravimetric analyser (TGA). The pyrolysis and co-pyrolysis reactions at different heating rates were categorised into different reaction zones. The single reaction zone for the PO mixture started from 221 to 510 degrees C, while the first, second, and third reaction zones for OPF started from 30 to 132 degrees C, 223-315 degrees C, and 299-557 degrees C, respectively. The first, second, and third reaction zones for the co-pyrolysis of PO mixture with OPF started from 210 to 319 degrees C, 298-382 degrees C, and 375-525 degrees C, respectively. The enthalpy changes were in the range of 355-146 kJ/mol, 149-164 kJ/mol, and 164-261 kJ/mol for PO mixtures, OPF, and their blend, respectively, under a heating rate that ranged between 5 and 20 degrees C/min. The thermal analysis of these materials indicated that the activation energies needed to achieve the thermal degradation of PO mixture were higher than for the thermal degradation of the OPF. The heating rate of 10 degrees C/min was found to be suitable for the co-pyrolysis of the samples based on the low activation energy. The results further showed that the co-pyrolysis of polyolefin mixtures with biomass could significantly reduce the energy inputs of the process by drastically reducing the activation energy of the reaction.