Catalytic Processing of Mixed Plastics Aiming for Industrial Reuse

The significant surge in global plastic waste has fundamentally shifted the traditional perceptions of plastic as a material. This shift can largely be attributed to established linear economy practices. While plastics offer numerous advantages, their postuse management has been grossly overlooked, resulting in ubiquitous plastic waste. In a circular economy framework for plastics, it is essential to methodically collect and recycle waste, rejuvenating the material for reuse. In this research, a model mixture of polymers, simulating household plastic waste, underwent thermochemical conversion to pyrolysis oil, priming it for the creation of new plastic products. Pyrolysis experiments utilized a bench-scale continuous fluidized bed reactor, employing various slags from the aluminum and steel industries as catalysts. All slags reduced the halogen content in the pyrolysis oil by 90 w/w% compared to the noncatalytic variant. Specifically, red mud further cracked the wax into lighter hydrocarbons, which is more suitable as a feed in the refinery. In parallel to the pyrolysis work, hydrotreatment experiments were conducted in a fixed bed reactor with the noncatalytic pyrolysis oil using 0.5 w/w% Pd/Al2O3 and 78 w/w% NiO/Al2O3 as catalysts to evaluate the halogen removal. Results indicated that the halogen content obtained by hydrotreatment was at the same level as that in the catalytic pyrolysis.