Coproduction of Value-Added Lube Base Oil and Green Diesel from Natural Triglycerides via a Simple Two-Step Process

A versatile process for coproducing green diesel and value-added lube base oil from natural triglycerides (e.g., vegetable oil, waste cooking oil, and microalgal oil) was developed. The two-step reaction process comprises (i) thermal oligomerization of triglycerides via Diels–Alder and/or radical-mediated addition of the CC bonds within the fatty acid units and (ii) catalytic deoxygenation of the oligomerized triglycerides via hydro-upgrading. Different triglyceride sources, that is, palm oil, soybean oil, and linseed oil, were investigated as the starting feedstock. Thermal oligomerization of the triglycerides at 300 °C proceeded at the expense of the CC bonds within the unsaturated fatty acid units. Thus, the degree of triglyceride oligomerization was enhanced when the reactant triglycerides contained more unsaturated fatty acid units (palm oil < soybean oil < soybean + linseed oil < linseed oil). The oligomerized triglycerides were subsequently deoxygenated over a Pt-MoO x /TiO2 catalyst, which converted the oligomerized and monomeric fatty acid units into lube base oil (C30–C54) and green diesel (C15–C18) fractions, respectively. The produced lube base oils were completely saturated with very high viscosity indexes (>120) and a nondetectable sulfur content, which could meet the specifications of high-quality group III lube base oil.