Synthesis of T-Type low-viscosity hydrocarbon bio-lubricant from fatty acid methyl esters and coconut oil

Biomass-derived long-chain alkanes with highly symmetrical branches, which show comparable properties to traditional petrochemical-based poly-α-olefin (PAO), have great potential economic value for industrial application. In this work, we developed a new strategy to prepare T-type low-viscosity bio-lubricant base oil using inexpensive lipid-derived fatty acid methyl esters (FAMEs) as raw materials with a total carbon yield of around 67.3%. The fatty acid methyl ester compounds (R₁-COOCH₃) were converted to fatty alcohols using methanol as the solvent and hydrogen donor over the Cu/SiO₂ catalyst. Subsequently, fatty alcohol was further brominated to the Bromo-Grignard reagents (R₁-CH₂-MgBr). In the next step, a T-type synthetic bio-lubricant base oil (R₁-C(R₂)-R₁) was formed by the hydrodeoxygenation of symmetrical tertiary alcohol precursors over Pd/C, where symmetrical tertiary alcohol precursors were obtained via the nucleophilic addition of Bromo-Grignard reagents with fatty acid methyl ester (R₂-COOCH₃). The specific properties of the branched representative bio-lubricant C_{32 (12'10'10')} are comparable to those of the commercial lubricant PAO 3.6. This strategy offered a new promising route for synthesizing high-quality bio-lubricant base oil.