caa a22 4500 463193423 CHVBK 20180406164915.0 cr unu---uuuuu 170326e20070101xx s 000 0 eng 10.1007/s10973-006-7898-2 doi (NATIONALLICENCE)springer-10.1007/s10973-006-7898-2 Influenceof aluminium precursor on physico-chemical properties of aluminium hydroxidesand oxides [Elektronische Daten] Part III. Al2(SO4)3·18H2O [Barbara Pacewska, Olga Kluk-Płoskońska, D. Szychowski] The process of hydrolysis of aqueous aluminium sulfate was carried on in ammonia medium at 100°C and for different time intervals (0, 20, 39 or 59 h). The products thus obtained were calcined at 550, 900 or 1200°C for 2 h with the aim to obtain aluminium oxides. The materials were studied with the following methods: thermal analysis, IR spectroscopy, X-ray diffraction, low-temperature nitrogen adsorption, adsorption-desorption of benzene vapours and scanning electron microscopy. Freshly precipitated material was an amorphous basic aluminium sulfate which after prolonged refluxing at elevated temperature in a mother liquor underwent a phase transformation into highly crystalline NH4Al13(SO4)2(OH)6 containing tridecameric unit Al13. It was accompanied by a decrease of specific surface area and the formation of a porous structure less accessible for benzene molecules. Regardless of the duration of the hydrolysis process, all products were characterised with poorly developed porous structure and hydrophilic character. Their calcination at the temperature up to 1200°C resulted in the formation of α-Al2O3 via transition forms of γ/η- and δ-Al2O3. The samples of aluminium oxides obtained after calcination at 550 and 900°C had higher values of specific surface area than starting materials due to processes of dehydroxylation and desulfurization. The process of calcination up to 900°C was reflected in developing of not only porous structure but also hydrophobic character of prepared materials. The S BET values calculated for the oxide samples obtained from aged products of hydrolysis at 1200°C were lower than for the analogous sample prepared without the ageing step. It was concluded that prolonged refluxing at elevated temperature of the products of hydrolysis of aluminium sulfate decreased thermal stability of final aluminium oxides. Springer-Verlag, 2006 metastable aluminium oxides nationallicence thermal decomposition nationallicence tridecameric Keggin structure nationallicence Pacewska Barbara Faculty of Building Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Łukasiewicza 17 St., 09-400, Płock, Poland aut Kluk-Płoskońska Olga Faculty of Building Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Łukasiewicza 17 St., 09-400, Płock, Poland aut Szychowski D. Faculty of Building Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Łukasiewicza 17 St., 09-400, Płock, Poland aut Journal of Thermal Analysis and Calorimetry Springer Netherlands 87/2(2007-01-01), 383-393 1388-6150 87:2<383 2007 87 10973 https://doi.org/10.1007/s10973-006-7898-2 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-006-7898-2 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pacewska Barbara Faculty of Building Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Łukasiewicza 17 St., 09-400, Płock, Poland aut NATIONALLICENCE 700 1- Kluk-Płoskońska Olga Faculty of Building Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Łukasiewicza 17 St., 09-400, Płock, Poland aut NATIONALLICENCE 700 1- Szychowski D. Faculty of Building Engineering, Mechanics and Petrochemistry, Institute of Chemistry, Warsaw University of Technology, Łukasiewicza 17 St., 09-400, Płock, Poland aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer Netherlands 87/2(2007-01-01), 383-393 1388-6150 87:2<383 2007 87 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence SWISSBIB 462029158 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer