Novel Sol–Gel Synthesis of Acidic MgF2−x(OH)x Materials |
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| Authors: | Stefan Wuttke Dipl‐Chem Simona?M Coman Prof?Dr Gudrun Scholz Priv‐Doz Dr Holm Kirmse Dr Alexandré Vimont Dr Maro Daturi Prof?Dr Sven?L?M Schroeder Dr Erhard Kemnitz Prof?Dr |
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| Institution: | 1. Humboldt University Berlin, Institute of Chemistry, Brook‐Taylor‐Stra?e 2, 12489 Berlin (Germany), Fax: (+49)?30‐20937277;2. University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, Bdul Regina Elisabeta 4‐12, 030016 Bucharest (Romania);3. Humboldt University Berlin, Institute of Physics, Newton‐Str. 14, 12489 Berlin (Germany);4. Laboratoire Catalyse et Spectrochimie, UMR 6506, CNRS‐ENSICAEN‐Université de Caen, Boulevard du Maréchal Juin, 14050 Caen Cedex (France);5. School of Chemical Engineering and Analytical Science, The University of Manchester, Sackville Street, Manchester, M60 1QD (UK);6. School of Chemistry, The University of Manchester, Manchester, M13 9PL (UK) |
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| Abstract: | Novel magnesium fluorides have been prepared by a new fluorolytic sol–gel synthesis for fluoride materials based on aqueous HF. By changing the amount of water at constant stoichiometric amount of HF, it is possible to tune the surface acidity of the resulting partly hydroxylated magnesium fluorides. These materials possess medium‐strength Lewis acid sites and, by increasing the amount of water, Brønsted acid sites as well. Magnesium hydroxyl groups normally have a basic nature and only with this new synthetic route is it possible to create Brønsted acidic magnesium hydroxyl groups. XRD, MAS NMR, TEM, thermal analysis, and elemental analysis have been applied to study the structure, composition, and thermal behaviour of the bulk materials. XPS measurements, FTIR with probe molecules, and the determination of N2/Ar adsorption–desorption isotherms have been carried out to investigate the surface properties. Furthermore, activity data have indicated that the tuning of the acidic properties makes these materials versatile catalysts for different classes of reactions, such as the synthesis of (all‐rac)‐α]‐tocopherol through the condensation of 2,3,6‐trimethylhydroquinone (TMHQ) with isophytol (IP). |
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| Keywords: | heterogeneous catalysis Lewis acids magnesium fluoride sol– gel processes vitamins |
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