Acid-base properties of MgCuAl mixed oxides
Résumé
MgCuAl layered double hydroxides (LDHs) with a hydrotalcite like structure containing different proportions of Mg2+ and Cu2+ cations have been prepared. Thermogravimetry and X-ray diffraction data indicated that the transformation of LDH into mixed oxides is effective after calcination at 723 K, irrespective of the composition. The acid-base properties of these mixed oxides have been investigated using adsorption microcalorimetry and X-ray photoelectron spectroscopy with NH3 (for acidity) and SO2 (for basicity) as probe molecules. Their catalytic behaviour for the conversion of cyclohexanol has been tested. The acid-base properties and the selectivity of catalysts has been related to their composition.
Mots clés
Basicity
adsorption
Acidity
Calcination
Calorimetry
Microcalorimetry
MgCuAl mixed oxides
Magnesium copper aluminide
Magnesium compounds
Phase transitions
Oxides
Catalysis
Catalyst selectivity
Composition effects
Crystal structure
Cyclohexanol
Cyclohexanol conversion
layered double hydroxides
Thermogravimetric analysis
XPS
X ray diffraction analysis
X ray photoelectron spectroscopy