Synthesis of green diesel through hydrolysis and hydrodeoxygenation reaction from waste cooking oil using NiMo/Al₂O₃ catalyst

Green diesel is a second generation of biofuel that has a potential to answer the energy needs in Indonesia, also in the world. The reactions used to produce green diesel are hydrolysis and hydrodeoxygenation by using NiMo/Al₂O₃ catalyst. Hydrolysis will change the triglycerides in the raw material, which is waste cooking oil into free fatty acids (FFA) and then converted into green diesel through hydrodeoxygenation. Hydrolysis of waste cooking oil carried out at temperature of 200°C and pressure of 16 bar for 3 hours with water and oil volume ratio of 1:1. FFA product of hydrolysis is as much as 73.89%. For hydrodeoxygenation, variation in operating condition used are 375°C with pressure of 12 bar and 400°C with pressure of 15 bar. Characterizations of green diesel have shown that both of hydrodeoxygenation products have met the specifications of diesel, except the acid number with optimum operating condition at 400°C and pressure of 15 bar. These conditions with NiMo/Al₂O₃ activated led to dominant yield of 68.87% of diesel fraction, selectivity of 69.58%, and conversion of 82.15%.