Nanocrystalline Metal Oxide-Based Catalysts for Biodiesel Production from Soybean Oil

High surface area (HSA) nanocrystalline metal oxides including TiO2, MgO, and CaO were obtained from Nanoscale Materials, Inc and used to make supported oxide catalysts for the transesterification reaction of soybean oil with methanol to fatty acid methyl esters (FAMES) or biodiesel. In order to improve conversion to biodiesel for the HSA catalysts, M-Acetylacetonate (AcAc) was supported on the surface, where M = Na, K, Ca, Li, V, Cu, Fe, Zn, and Al. The AcAc was contacted with the HSA nanocrystalline metal oxides in an organic solvent in order to adsorb the AcAc onto the surface. The excess AcAc was washed and the resulting catalyst was heat-treated in air or under vacuum to decompose the AcAc. The catalysts were compared based on conversion at three temperatures; 25, 50, and 80°C. The best catalysts tested were CaO and alkali and alkaline AcAc supported on MgO and TiO2, which produced highly basic catalysts. The reaction appears to be structure sensitive over MgO since using larger MgO particle sizes resulted in higher conversions compared to HSA MgO on a per mass basis. The greatest challenge was increasing the reusability of the catalyst where, surprisingly, vacuum treated V-AcAc/TiO2 retained significant portions of its activity for use in multiple reactions.