High-efficient production of biofuels using spent fluid catalytic cracking (FCC) catalysts and high acid value waste cooking oils

The conversion of high acid value (AV) waste cooking oils (WCOs) into biofuels was studied using the cracking process over spent fluid catalytic cracking (SFCC) catalysts. The processing of WCO was carried out in a fluid catalytic cracking lab-scale unit with temperatures ranging from 450 to 520 °C. From 480 °C, whatever the spent catalysts, WCOs with AV in range of 6–22 mgKOH/g can be converted to liquid fuels with the near zero AV (AV < 0.5 mgKOH/g). The yields of diesel, gasoline, LPG are in range of 25–29 wt%, 40–42 wt% and 14–18 wt%, respectively, while the coke formation is limited at 5–6 wt%. The increase of temperature to 520 °C enhances the conversion of diesel to gasoline and LPG. The presence of ZSM-5 in SFCC catalyst leads to an increase in propylene and LPG yields. Otherwise, higher rare earth content could limit the zeolite destruction, resulting in a better catalytic cracking activity. This study reports a remarkable approach that encourages the simultaneous utilization of multiple hazardous substances, SFCC catalysts and WCOs, as low-cost raw materials for biofuel production. Finally, after biofuel production, the SFCC catalysts can also be reused to produce high purity of a concentrate of La and Ce. • Spent FCC catalysts were used to convert waste cooking oils (WCOs) to fuels. • From 480 °C, WCOs can be cracked to near zero AV liquid fuels. • Product yields: 25–29 wt% of diesel, 40–42 wt% of gasoline, 40–42 wt% of LPG. • SFCC catalysts with higher RE content resulted in higher cracking activity. • High purity of La and Ce can be recoverd from SFCC catalysts after used.