Waste-to-energy: Pyrolysis-gasification conversion of packaging waste from the both micro and macro perspectives

The increasing volume of packaging waste, a representative component of municipal solid waste, has raised considerable environmental concerns. The present study conducted a detailed investigation into kinetic and thermodynamic of pyrolysis-gasification for post-consumer beverage cartons (BCs). Subsequently, the conversion was simulated using reactive force field molecular dynamics (ReaxFF-MD) to outline a proposed conversion pathway. Techno-economic assessment (TEA) was then conducted to evaluate economic performance of BCs conversion at different scales. The BCs decomposition could be divided into four stages of <375, 375-500, 500-800 and 800-900 °C with mass loss of 51.3-60.6, 19.0-25.3, 4.9-12.3 and 2.5-4.7 wt.%, respectively. Fourier transform infrared spectrometry and mass spectrometry confirmed the evolution of olefins, alkynes, and diolefins. The mean activation energy was calculated to be 60.2 kJ mol^-1 within conversion of <0.60, which increased significantly to 205.9 kJ mol^-1 for greater conversions. Positive changes in enthalpy and Gibbs free energy confirmed the endothermic and non-spontaneous nature of the pyrolysis-gasification reaction. The products generated and reactions involved in ReaxFF-MD simulation corresponded with the mass spectrometry results, indicating that β-scission of radicals was the predominant pathway for olefin formation. TEA analysis revealed that larger plants (45000 tonnes/a) had greater revenue potential, profitability, and positive returns on investment.