Low temperature pyrolysis of waste cooking oil using marble waste for bio-jet fuel production

Limestone powder, a by-product of top-down marble processing, exhibited high thermal stability and functionality as catalysts for the low-temperature pyrolysis of waste cooking oil (WCO) into biofuel. The marble waste (MW) contains calcite, dolomite, and quartz composites (CaCO₃/MgCO₃/SiO₂) as non-uniform microcrystallites. Pyrolysis at 380 °C in 1 h increased the hydrocarbon composition of biofuel and reduced carboxylic acid. The biofuel composition contains 80 % hydrocarbon within the jet fuel C8-16 ranges. MW reduced the carboxylic acid concentration from 49 % in catalyst-free pyrolysis to less than 4 %. The optimum condition was obtained at 3 % MW, yielding 43.55 % linear hydrocarbon, 11.1 % cyclic hydrocarbon, and 1.02 % aromatic compounds that satisfied the bio-jet fuel classification. The incorporation of varying percentages of marble waste demonstrates a significant enhancement in the cyclic compounds, elevating the yield from ∼3 % in catalyst-free pyrolysis to an impressive ∼35 %. The hydrocarbon yield is higher when using 3%MW > 1%MW > 6%MW > 9%MW. Dolomite and calcite mixture in MW catalyzed triglyceride conversion to hydrocarbon by adsorbing carbonate in triglycerides to drive C–O bond dissociation. These studies provide a roadmap for the utilization of abundant resources locally available in Indonesia to sustain local energy demand.