Conversion of higher fatty acids or higher fatty acid esters to long-chain alkanes by acid added metal catalyst under mild hydrothermal conditions

Utilizing waste lipids to produce renewable diesel has received widespread attention, but the traditional preparation process is limited by rigorous reaction conditions or complex catalytic systems . This study reports a simple acid addition method to improve the conversion of higher fatty acids and/or higher fatty acid esters into long-chain alkanes under mild hydrothermal conditions over commercial Ru/C catalyst. The pretreatment of water-containing lipids, as well as the preparation process of complex catalysts are avoided, and the scope of applicable raw materials is expanded and the reaction system is simplified. This catalytic system is suitable for the conversion of most lipid materials into long-chain alkanes. Under the optimized conditions, stearic acid is converted completely with 97.85% selectivity of long-chain alkanes at 180 °C for 3 h. The catalytic system maintained excellent activity during the five repeated reactions.