SolvX: Solvothermal conversion of mixed waste plastics in supercritical toluene in presence of Pd/C catalyst

As the world's ability to cope with the fast-rising output of disposable plastic products is limited, plastic pollution has emerged as one of the most important environmental challenges. Catalytic solvothermal conversion (SolvX) could potentially utilize mixed waste plastics (MWPs) for sustainable fuels and chemical production. In this study, the effect of SolvX reaction time (1 - 5 h), Pd/C catalyst loading (0 - 10 wt%), and hydrogen loading (0-75 bar) on MWPs were investigated using supercritical toluene as solvent at temperature 350 degrees C. Four major waste plastics including low-density polyethylene (#4), polypropylene (#5), polystyrene (#6), and polyurethane (#7) were used as feedstock for this study. Along with SolvX conversion, the liquid products (crude oils) were characterized for elemental composition changes using ultimate analysis, boiling point distribution via ther-mogravimetric analysis, functional groups alteration using Fourier transform infrared spectroscopy, and product identification via gas chromatography-mass spectrometry. The results showed that the addition of catalyst and hydrogen have positive effects on the SolvX conversion. According to the elemental analysis, the SolvX crude oils' higher heating values (HHV) range from 32 to 38 MJ/Kg. The range of boiling points demonstrates that Pd/ C increases the formation of lighter hydrocarbons. Additionally, a proposed catalytic SolvX reaction mechanism shows that the aromaticity raised with the increment of residence time and Pd/C enhances hydrodenitrogenation and deoxygenation at higher hydrogen loading.