Al–Fe pillared clays: Synthesis, characterization and catalytic wet air oxidation activity

Mixed (Al–Fe) pillared clays with different Fe/(Al+Fe) molar ratios were synthesized by exchanging the interlayer charge compensating cations of clay by polyoxocations containing iron and aluminum. The obtained materials were characterized by powder XRD and nitrogen physisorption. Potentiometric titration was applied to study the surface properties of the solids; a description of the acidity is given in terms of a pKa distribution of surface species. Al–Fe pillared clays are efficient catalysts for gallic acid wet air oxidation at mild conditions (363 K and 5 bar air pressure).