New ways of preparation of high-surface area granulated alumina supports

The paper describes the properties of hydroxoaluminocarbonates (dawsonite NH4Al(OH)2CO3, scarbroite Al5(OH)13(CO3)·5H2O) and their application as additives in alumina synthesis. Comparing scarbroite and dawsonite, it was found that the size of the coherent scattering region of scarbroite (25.0–40.0 nm) was higher than that of dawsonite (11.0–22.0 nm). According to FTIR spectra, scarbroite calcined at 550 °C has higher amount of residual surface CO32–groups than calcined dawsonite. The presence of CO2 in calcined scarbroite was confirmed with IR-Fourier analysis of gas decomposition products. The Al2O3 samples prepared by calcination of hydroxoaluminocarbonates at 550 °C contained X-ray amorphous phase. The Al2O3 sample obtained from scarbroite contained a small amount of γ-Al2O3. By addition of dawsonite/scarbroite to pseudoboehmite for granulated aluminum oxide, it was possible to significantly increase the specific surface area from 223 to 243–298 m2/g, pore volume from 0.48 to 0.62–0.81 cm3/g and water capacity from 0.49 to 0.9–1.2 cm3/g.