The direct synthesis of a bio-lubricant by the oligomerization of methyllinoleate via castor oil

Lubricating oil is one of the important types of petrochemical products widely used in industry. However, traditional petroleum-based lubricants, which are associated with exhausting fossil resources, pose a great hazard to the environment owing to their non-degradability. Castor oil, as a type of vegetable oil, is a promising candidate to replace mineral oil to alleviate energy stress and protect the environment. Herein, we report a novel strategy for developing a non-noble metal catalyst for the oligomerization of methyllinoleate to directly produce bio-lubricant oil. The obtained dimers and higher oligomers of methyllinoleate were produced with a high conversion of 99.9% and a maximum yield of 70.8% using a molybdenum-containing silica-alumina catalyst under optimised conditions. The superior activity was attributed to the highly dispersed MoO3 nanoparticles on the surface of the silica-alumina support. The polymerization mechanism of the Mo-based catalyst for this eco-friendly oligomerization process was proposed and verified using density functional theory (DFT) calculations to provide a better understanding of the catalytic mechanism.