Production of Biofuel Additives from Glycerol Etherification Using Zirconia Supported Phosphotungstic Acid

Using etherification to convert glycerol into biofuel additives is an effective way to solve the current problem of excess glycerol. In this study, a series of environmentally friendly (x)HPW/ZrO 2 catalysts were synthesized for the etherification of glycerol and tert-butyl alcohol (TBA). The internal microstructure and acidity analysis of the synthesized samples were derived from BET, XRD, Raman spectroscopy, FTIR, SEM, NH 3 -TPD and Py-FTIR. The results revealed that the synthesized catalysts retained the complete Keggin structure of phosphotungstic acid (HPW) which supported on it. The (15)HPW/ZrO 2 catalyst with suitable structure and acidity had an excellent catalytic effect on the etherification reaction. Driven by the (15)HPW/ZrO 2 catalyst, the optimal reaction conditions were determined from parameters of reaction temperature, time, molar rate of glycerol and TBA, and catalyst dosage. 93.2% glycerol conversion and 42.5% selectivity of multi-substituted tert-butyl glycerol ethers (DTBG + TTBG) were obtained under optimal conditions. In addition, even after a total of four consecutive reactions, (15)HPW/ZrO 2 catalyst still demonstrated relatively good catalytic activity. Graphic Abstract