Biodiesel production from sunflower oil by tungsten oxide supported on zirconium doped MCM-41 silica

A series of zirconium doped MCM-41 silica supported WOx solid acid catalysts, with WO3 loading ranging from 5 to 25 wt%, has been prepared by impregnation with ammonium metatungstate. After activation at 700 °C, these catalysts are active in the transesterification of sunflower oil with methanol at 200 °C, with a biodiesel yield higher than 80% after 2.5 h of reaction. The maximum activity (82 wt% of FAME yield) is found for the catalyst with 15 wt% WO3 loading, which is able to simultaneously catalyze the esterification and transesterification of simulated used oils, with an acidity degree as high as 9.1%. Moreover, this catalytic activity is maintained in the presence of 5 wt% of water and after three cycles of reutilisation, without any treatment of the catalyst.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (159 K)Download as PowerPoint slideResearch highlights▶ Zirconium doped MCM-41 silica supported WOx solids are a new family of active acid catalysts for the methanolysis of sunflower oil. ▶ Their activity is maintained after three catalytic cycles. ▶ These acid catalysts simultaneously catalyze the esterification of fatty acids and the transesterification of triglycerides.