Biphasic catalytic upgrading of biodiesel produced from non-edible biomasses

The growing demand for edible oils for food and fuel has increased interest in non- edible oils like waste cooking oils (WCOs) for biodiesel production. However, biodiesel faces challenges, such as low oxidative stability and poor cold flow properties. These fuel properties are influenced by the composition of fatty acid methyl esters (FAMEs), particularly their degree of unsaturation. While compression ignition (CI) engines can accommodate up to 30% biodiesel blends with diesel without modification, higher biodiesel content requires engine upgrades. This study explores the upgrading of the WCO biodiesel sample via partial hydrogenation of its polyunsaturated FAMEs catalyzed by the in-situ synthesized water-soluble Ru/TPPTS. The methodology includes EN ISO standard methods and gas chromatography-mass spectrometry (GC-MS) analysis for WCO biodiesel sample characterization before and after upgrading. The results demonstrate that the Ru/TPPTS catalytic system effectively altered the composition of the biodiesel. Specifically, the catalytic system significantly reduced the percentage of unsaturated linoleic acid (C18:2) methyl ester while concurrently increasing the percentage of saturated stearic acid (C18:0) methyl ester. This compositional change led to an increase in the oxidative stability of the hydrogenated biodiesel sample. Nevertheless, further research is needed to meet the limit outlined by the EN ISO standard.