Valorization of food waste impurities by catalytic co-pyrolysis for production of pyrolysis oil with high energy potential

Abstract

The emerging impurities (plastic, chopsticks, eggshell and bones) in food waste (FW) due to inefficient source separation have hindered the sustainable treatment and valorization of FW. This study evaluated pyrolysis for converting FW with and without different impurities to produce pyrolysis oil (py-oil). The optimal yield of total condensable vapor (py-liquid) of 37.52 wt% from pure FW was achieved at 400 °C, 20 °C/min and 20 min. Different FW impurities demonstrated varieties of relative content of hydrocarbon (35.53 wt% − 58.03 wt%). The introduction of polypropylene, eggshells and bones improved the organic fraction of py-liquid from 6.5 wt% to 10.7 wt%. Polypropylene enhanced the selectivity of hydrocarbons, while other impurities reduced the hydrocarbon selectivity. Adding treated eggshells and activated biochar as catalysts significantly increased aromatic and aliphatic hydrocarbon production with higher heating values (HHV) ranging from 36 MJ/kg - 44.44 MJ/kg. The C-H and C-O ratio of py-oil indicated that py-oil has the potential to be processed and utilized like conventional liquid fuel.