Structure and reactivity of silica-supported zirconium sulfate for esterification of fatty acid under solvent-free condition Original Research Article

The structure and reactivity of silica-supported zirconium sulfate (ZS) with 10–50 wt% loading prepared by impregnation method are studied by using X-ray diffraction (XRD), surface area measurement, TG, FTIR-pyridine and XPS. It is found that most of ZS in samples is well dispersed on the support. However, at loading higher than 40 wt%, ZS exist as small agglomerate crystalline particles with an average size around 23.8–32.1 nm, calculated by XRD results. Based on various characterizations on various techniques, it may be concluded that ZS forms interaction with the silica support, which is responsible for the high dispersion and the enhanced acidity of these systems. The effects of different loading on the reactivity of silica-supported ZS is studied by using esterification of fatty acid under solvent-free conditions as a probe reaction, and the reactivity is found to be strongly loading related. The reaction also shows that the silica-supported ZS exhibits a higher activity than that of bulk ZS and conventional acid resins.