Process optimization for continuous production of sustainable biodiesel from completely non-edible biomass, lignocellulosic hydrous ethanol and waste fatty acids

This work developed a continuous production process of sustainable biodiesel from completely non-edible biomass to replace first generation one from fossil derived methanol and edible oils. Hydrous bioethanol obtained from woody biomass (without the standard dehydration that requires a significant energy input) and waste fatty acids generated as by-products of edible oil refining were used as feedstocks. Esterification was performed using a porous cation-exchange resin in conjunction with ethanol having water levels of 0 to 15 wt%, in both batch and continuous systems. High fatty acid conversions of more than 90% were obtained in both systems by optimizing the reaction time, even with a water concentration in the ethanol as high as 15 wt%. Because the resin was found to maintain its catalytic activity over time, this technology is expected to assist in the development of future sustainable fuel systems.