Sol-gel synthesis and properties of nanoscopic aluminum fluoride
Aluminum fluoride (HS-AlF3) prepared via sol-gel synthesis route under non-aqueous conditions exhibits high surface area and an extremely strong Lewis acidity, comparable with some of the strongest known Lewis acids such as SbF5 and ACF. The basis of its unusual properties is the sol-gel fluorination of aluminum alkoxide with anhydrous HF in organic solvents yielding first an amorphous catalytically inactive precursor with high surface area, which can be dried and eventually post-fluorinated to get HS-AlF3. In this thesis, all steps of the synthesis route were thoroughly investigated. The results of these investigations together with detailed analysis of the obtained materials are reported and discussed. HS-AlF3 supported on Al2O3 with different HS-AlF3 loadings was prepared by wet impregnation method. The properties of the HS-AlF3/Al2O3 samples as Lewis acid catalyst were evaluated for CHClF2 dismutation and CBrF2CBrFCF3 isomerization. The preparation of AlFyOx via sol-gel method is also reported. AlFyOx prepared is amorphous and have high surface are up to 240 m2/g.
School:Humboldt-Universität zu Berlin
Source Type:Master's Thesis
Keywords:Lewis-Acidität katalysierter Halogenaustausch Sol-gel synthesis nano-alumnium fluoride Lewis acidity catalyzed halogen exchange nano-aluminum oxide
Date of Publication:10/02/2007