A simple aqueous phase synthesis of high surface area aluminum fluoride and its bulk and surface structure

• Published in: Inorganica Chimica Acta Vol. 359; no. 15; pp. 4851 - 4854
• Main Authors: Kleist, Wolfgang, Haeßner, Carmen, Storcheva, Oksana, Köhler, Klaus
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2006
• Subjects: Aluminum fluoride synthesis; High surface area; Surface structure; Aluminum fluoride synthesis; High surface area; Surface structure
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2006.07.105

Al 2 O 3 + 6 HF ( aq ) → r . t . H 2 O 2 AlF 3 + 3 H 2 O The preparation of high surface area aluminum fluoride (60–120 m 2/g) from Al 2O 3 and aqueous HF solution is reported. Various characterization techniques, including X-ray powder diffraction, infrared and solid state NMR spectroscopy, and adsorption of paramagnetic probe molecules (vanadium complexes), were used to prove that both bulk and surface structure consist of AlF 3. No oxide or hydroxide species could be observed in significant amount. A simple novel synthesis route to aluminum fluoride, AlF 3, from aqueous phase is reported. Al 2O 3 is dissolved in aqueous hydrofluoric acid, HF, and re-precipitated as AlF 3 · 3H 2O. Thermal decomposition results in thermally stable AlF 3 with high specific surface areas between 120 and 60 m 2/g depending on treatment temperatures (up to 450 °C). Bulk and surface structures of the resulting amorphous and crystalline materials were characterized by X-ray powder diffraction, infrared and solid state NMR spectroscopy ( 27Al, MAS), nitrogen physisorption and adsorption of paramagnetic probe molecules (vanadium complexes).