Process Analysis of PMMA Dental Waste Depolymerization in Semi-Batch Reactors

This study examines the chemical recycling of polymethylmethacrylate (PMMA) dental waste via pyrolysis in a semi-batch fixed-bed reactor, aiming to convert it into the valuable monomer methyl methacrylate (MMA). Experiments were conducted in a 2L reactor at temperatures of 425 °C, 450 °C, and 475 °C to understand the effects of heating rate and temperature on product yield and composition. Results show that at 425 °C, MMA was the primary liquid component, with minimal by-products, suggesting that lower temperatures enhance monomer recovery. Higher temperatures, however, increased gas yields and reduced MMA yield due to intensified thermal cracking. The study also highlights that char formation and non-condensable gases increase with reactor scale, indicating that heat transfer limitations can influence MMA purity and yield. These findings emphasize that for effective MMA recovery, lower temperatures and controlled heating rates are optimal, especially in larger reactors where heat transfer issues are more prominent. This research contributes to scaling up PMMA recycling processes, supporting industrial applications to achieve efficient monomer recovery from waste.