The effect of glucose on the formation of the nanocrystalline transition alumina phases

Series of alumina powders were synthesized starting from sodium aluminate solution prepared from Bayer liquor. The neutralisation of sodium aluminate solution was performed with the use of sulphuric acid. The influence of glucose as a non-surfactant additive on the structure of alumina powders at moderate pH was investigated. The results show that the properties of the powders are influenced by the initial pH value of the solution, as well as the duration of the neutralisation step. High pHs lead to the formation of powders with heterogeneous structure with bayerite as a dominant phase, which during calcinations converts to eta-alumina with high surface area. Addition of glucose to the starting aluminate solution leads to the formation of nanocrystalline boehmite with estimated average crystallite size less than 3 nm and high surface area (above 300 m(2)/g). After calcinations, boehmite transforms to gamma-alumina. The results have shown that during the heat treatment, structural transformations proceeded simultaneously with the significant changes in the textural properties of the obtained mesoporous gamma- and eta-alumina powders. (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.