Thermal and morphological study of Al2O3 nanofibers derived from boehmite precursor

Abstract

The boehmite nanofibers were prepared by using NaAlO2 and Al2(SO4)3 as the starting materials without any surfactant. The phase transitions of the boehmite nanofibres against different temperature were studied and various phases were derived from well-crystallized boehmite nanofibers. All these phases had the same morphology even after high temperature calcination. In addition, the retention of specific surface area of the samples were very high because of the limited aggregation occurred in calcinations for each sample. For instance, the γ-Al2O3 obtained at 500 °C had the specific surface area (208.56 m2/g) with an average pore diameter of 6.0 nm. With the further increase of the calcination temperature, the nanofibers became shorter and coarsening, which resulted in the decrease of the specific surface area. It is worthwhile to notice that the BET surface areas (40.97 m2/g) and the pore volume (0.27 cm3/g) of the fibrous structures obtained after 1200 °C calcination are substantially higher than that of the non-fibrous alumina because of the morphology maintenance.