Methanolysis of sunflower oil catalyzed by acidic Ta2O5 supported on SBA-15

Tantalum penta-ethoxide has been used as precursor for the preparation, after calcination at 575 °C, of a series of catalysts based on tantalum oxy-hydrate supported on SBA-15 silica. The Ta2O5 loading ranges between 5 and 25 wt%, and all of them exhibit acid properties, as determined by NH3-TPD. These catalysts have been assayed in the methanolysis of sunflower oil at 200 °C, being the catalyst with a 15 wt% of Ta2O5 the most active, giving 92.5% of biodiesel yield with solely 6.7% of catalyst with respect to the oil weight. Moreover, no leaching of tantalum was detected in the liquid medium, and these catalysts are able to simultaneously produce the esterification of free fatty acids (FFAs) and the transesterification of triglycerides, even in the presence of 9% of FFAs. The catalytic activity is well maintained in the presence of 5 wt% of water and after three cycles without any treatment.

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► Acid solids were prepared by impregnation of a SBA-15 silica with Ta2O5.
► The catalysts are active in the methanolysis of sunflower oil at 200 °C.
► No leaching of tantalum is detected and catalysts can be reutilized.
► These acid catalysts catalyze the FFAs esterification of and oil transesterification.