Solid acid catalysts for interesterification of C8-triglyceride to one-pot FAEE derivatives and its additives

The widespread of circular and green economy trend is boosting the research towards sustainable production of biofuels like biodiesel. Homogeneous catalyzed transesterification of vegetable oils is to date the main used process to produce biodiesel albeit the drawbacks related to catalyst and glycerol separation from biodiesel. In order to avoid these drawbacks the triglycerids interesterification represents a good alternative in order to produce at the same time the FAEE (fatty acid ethyl esters) and triacetylglycerol (TAG) as additive. In the present work, we investigate different solid acid catalysts based on functionalized silica and titania supports on the interesterification of glyceryltrioctanoate as molecule model for the achievement of ethyl biodiesel already added with its additives. The catalytic performance of the synthesized materials was evaluated by using an excess of ethyl acetate with and without the presence of ethanol. The reaction was monitored by GC-MS analysis during 24h. Formation of monoacetyldiglicerides (MADG) and diacetylmonoglicerides (DAMG) was observed with all the catalysts. TAG was obtained only in the presence of ethanol, which actually, allowed the alcoholysis of triglycerides and, as consequence, the shift towards the formation of TAG. According to preliminary results, the best catalytic activity was achieved with SiO2 based materials, due to the synergistic effect of silanol and acid surface groups in promoting the ester hydrolysis. The surface and structural properties of the catalysts were investigated by means of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermo-gravimetrical analysis (TGA), N2 adsorption isotherms and acid capacity measurements performed on both fresh and spent materials.