Structural characterization and catalytic properties of aluminum borates–alumina catalysts

Abstract

A series of aluminum borate–alumina catalysts of different composition was prepared with the co-precipitation method. The structural and phase changes were studied by thermal analysis, X-ray diffraction (XRD) and FT-IR techniques. Thermal treatment of solid aluminum borates–alumina led to the formation of different phases namely, γ-Al2O3, α-Al2O3, 2Al2O3-B2O3 and 9 Al2O3-2B2O3, where the formation of the latter two phases was observed in the temperature range of 840–900°C. The surface acidities were determined using the spectrophotometric method. Cracking of ethylbenzene and dehydration (DHD) of isopropanol and ethanol were investigated on the calcined catalyst using the pulse microcatalytic technique. The boron contents and the calcination temperature are important factors in determining the structural properties and catalytic activities of these catalysts. The results also indicated that the surface acidities were found to increase with increasing boron contents of the samples and decreased with the calcination temperatures. Therefore, the catalytic activities of the investigated catalysts were found to be structurally sensitive.