Molecular\nComposition of Impurities in Used Cooking\nOil and Their Effect on Hydrotreated Biofuel Quality

Biodiesel and biojet fuel production from hydrogenation\nof used\ncooking oil (UCO) is one of the essential measures to achieve global\nenergy transition and sustainable development. A systematic molecular\ncomposition characterization method of UCO feedstocks and their hydrotreated\nproducts has been established to trace the undesirable components\nduring the industrial hydrogenation process. The influences of soluble\nhydrocarbons and oxygen-containing impurities in UCOs on the hydroconversion\nof UCO into green diesel were researched by analyzing specific low-quality\nUCO feedstocks and products obtained from industrial production process.\nThe results revealed that some common bioactive constituents abundant\nin low-quality UCOs may be responsible for the unqualified properties\nof the hydrotreated oils. Steradienes and sterols can convert to high\nboiling point substances and decrease the yield of green diesel. Tocopherols\nare a potential source of abnormal monocyclic aromatic hydrocarbons\nin hydrotreated oils and affect the properties of fuel. This study\nproposed that some soluble hydrocarbons and oxygen-containing impurities\nin the industrial UCO feedstocks can also significantly affect the\nquality of biofuels, which has not been mentioned in previous works.\nThe detailed characterization of UCO feedstocks and their hydrotreated\nproducts offers valuable insights for quality control of feedstock\nand process optimization in biofuel production, contributing to conversion\nof low-quality UCO feedstocks to highly valuable biofuels.