Influences of processing techniques of the H 2O 2-precipitated pseudoboehmite on the structural and textural properties of γ-Al 2O 3

Abstract

Influences of three post-precipitation techniques, n-butanol azeotropic distillation, ethanol washing and water washing of the H 2O 2-precipitated pseudoboehmite (PB) from sodium aluminate (SA) solutions on the structural and textural properties of γ-Al 2O 3 upon calcination were comparatively studied. The first two processing techniques not only yield folded and swollen sheet-like pseudoboehmite and γ-Al 2O 3 nanofibres, but also increase their macro-mesopore volume and specific surface area significantly. The mechanisms for the formation of nanofibres and macro-mesopore volume induced by butoxy group or ethoxy group were also proposed. In contrast, n-butanol azeotropic distillation is more competitive for widening pores and preventing them from collapsing due to its larger n-butanol molecules, longer butoxy groups and the more complete replacement of residual water in the precipitate. The γ-Al 2O 3 from azeotropic distillation exhibits more excellent macro-mesostructure with high surface area (about 4.21 cm 3/g and 396.3 m 2/g) than those of the γ-Al 2O 3 from ethanol washing (about 2.23 cm 3/g and 222.0 m 2/g).