Transesterification of methyl oleate for biolubricant production over K2CO3/activated carbon catalyst under conventional and microwave heating

Trimethylolpropane fatty acid triester (TFATE) as an environmentally friendly biolubricant is a promising alternative to mineral-based lubricants. However, the synthesis of TFATE by transesterification reaction has the issues of difficult catalyst recovery and slow reaction rate. In this work, K₂CO₃/activated carbon (AC) catalyst was prepared and used in the transesterification of methyl oleate (MO) with trimethylolpropane (TMP) for TFATE production. Reaction conditions including agitation speed, N₂ flow rate, catalyst amount, catalyst loading, MO to TMP molar ratio, and temperature were optimized, with the highest TFATE selectivity of 93.7% obtained. To further increase the reaction rate, microwave heating was employed to intensify the process. The kinetic study demonstrated that the rate constants of the three consecutive transesterification reactions for TFATE synthesis were enhanced by the microwave irradiation, which was mainly attributed to the “hot spot effect” of the microwave heating. Moreover, the K₂CO₃/AC catalyst was recycled and reused for five times, with no significant change in catalyst performance was observed.