Molecular insights into supercritical water gasification process of polyoxymethylene plastics

Abstract

Effective plastic management is crucial in addressing the growing environmental challenges posed by plastic pollution. Among various plastics, polyoxymethylene (POM) stands out as a widely used engineering thermoplastic with significant applications in industries. Innovative recycling solutions are essential to mitigate its environmental impact. This study investigates the supercritical water gasification (SCWG) of POM plastics at a molecular level using reactive molecular dynamics simulations. The research aims to provide insights into the factors influencing the SCWG process. Key findings reveal that temperature significantly affects reaction mechanisms, while the primary syngas products include hydrogen, carbon monoxide, and carbon dioxide. A notable trend observed is the increase in activation energy as water content increases, highlighting the importance of optimizing hydration levels for efficient conversion. The calculated activation energies range from 106 to 135 kJ/mol, aligning well with experimental findings (160 kJ/mol). The study validates the computational approach by demonstrating excellent agreement between simulation results and experimental findings on the molar fraction of gas and activation energy, underscoring its reliability as a predictive tool for process design and optimization. Furthermore, the research contributes to sustainable waste management by offering strategies to enhance SCWG efficiency.