Sonocatalytic Biodiesel Transesterification to Produce a Lubricant

Abstract

The growth of the machinery and automotive industry drives interest toward the production of biolubricants due to their better lubricating properties and their low carbon footprint compared to petroleum-based lubricants. However, their traditional synthesis is long and energy-intensive. We intensified the production of biolubricants from canola oil methyl esters using ultrasound. NaOH catalyzed the transesterification of two polyalcohols (propylene and trimethylene glycols). We varied the ultrasound power, temperature, type of alcohol, and alcohol/ biodiesel molar ratio. Trimethylene glycol produced 90 ± 1.9% of biolubricant at 80 °C and 62 W with a molar ratio of 0.25. Calcium oxide supported on silica (CaO/SiO 2 ) also catalyzed the reaction under optimal conditions. The yield of the CaO/SiO 2 -catalyzed reaction was two times lower than that obtained with NaOH. We surveyed the loading of CaO over SiO 2 , the catalyst loading in the reactor, and its leaching and reusability. A mass percentage of 50% CaO to SiO 2 yielded 46 ± 3.2% lubricants at 3% by weight of the reactants' total mass. After three reaction cycles, the ultrasound did not alter the particle size (e.g., mean diameters of fresh and used catalysts were 31 and 32 μm, respectively), but it leached the active sites, which reduced the activity of the catalyst for successive uses.