Exergy and energy analysis of pyrolysis of pretreated single-use waste plastics

The kinetics of the pyrolysis of real-life mixed single-use waste plastics were assessed using experimental data from a lab-scale batch reactor by conducting a nonlinear least square curve fitting. The optimizing effect of waste plastics pretreatment on product yield, energy and exergy efficiency of the pyrolysis process was investigated. Process parameters such as energy recovery ratio, energy combustion ratio, and others were considered. The best-fitting kinetic model for mixed single-use plastics (raw and pretreated) was Avrami-Erofeev. Energy and exergy efficiencies obtained from pyrolyzing raw and pretreated single-use waste plastics were in the range of 17–42 % and 35–74 %, respectively. It was revealed that pyrolyzing pretreated feedstock compared to raw SUP increased the oil/wax yield from 62.61 ± 0.41 % to 79.38 ± 0.48 %. This work provides a reliable assessment of the potential of pyrolysis to efficiently convert mixed waste plastics to fuel. • Pretreating SUP via thermal extrusion improves the yield of oil/wax products. • The optimal temperature for pyrolysis of mixed SUP to enhance oil yield is 500 °C. • The exergy efficiency of SUP pyrolysis can improve to 74 % after feedstock pretreatment. • The activation energy for mixed SUP is 155–172 kJ/mol.