Influence of OH/metal ratio on the stability of alfe-pilc catalyst for wet peroxide oxidation of phenol

Abstract

AlFe-pillared clay catalyst with OH/metal = 4; 5 mmol metal/g clay and Al: Fe = 5:5 swells intensively in phenol-water solution and has no measurable catalytic activity in phenol removal from water solutions, on contrast to the similar catalyst with OH/metal = 2. The different behavior of two samples can be explained first of all by differences in iron ion distribution in catalysts as a consequence of applied pillaring solutions prepared at different OH/metal ratios. In the sample with OH/metal = 2 iron ions are uniformly distributed on the AlFe-pillars, while in the sample with OH/metal = 4 iron ions appear not only on the pillars but also as a bulk FeO.Fe2O3-form. The results obtained by FTIR, SEM, TPR and Mössbauer spectroscopy reveal the differences in acid-base properties, morphology and iron ion distribution in the samples. © Akadémiai Kiadó, Budapest. All rights reserved.