Catalytic activity of phenol oxidation over iron and cooper-exchanged pillared bentonite

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Abstract Al, mixed Al-Fe and Al-Cu pillared clays were prepared. The solids were characterized by X-ray diffraction (XRD), N2 adsorption and H2-TPR. The dispersion of the cold clay suspension, before the pillaring, increases the basal spacing and the specific surface area. CWPO of phenol under mild conditions (25 °C, 1 atm) was carried out without correction of pH. Mixed Al-Fe and Al-Cu pillared clays have comparable performances, although they showed some differences in the H2O2 decomposition kinetics. A total conversion of H2O2 is obtained without the complete phenol conversion over mixed Al-Fe pillared clays suggesting the presence of active species in these catalysts. In a slight excess of H2O2, the activity increased for all iron-based clays catalysts with the increase in Fe content. A total conversion of phenol is obtained after 15 h of reaction over Fe/MR-AlFe(10) and after extending the reaction time to 30 h in the presence of Fe/MR-Al. While MR-AlFe(10) only converted 57.12% under the same conditions. MR-AlFe(10) has the greater basal space (17.44 Å) and is more active for H2O2 decomposition than Fe/MR-Al, which certainly allowed greater accessibility of the reactant to the iron species. Iron exchanged and post-pillared clay with mixed (Al-Fe) solution containing 10% of iron expressed as molar percentage {Fe/MR-AlFe (10)} was the most efficient for this reaction combining good catalytic activity with high stability against iron leaching (0.02%). It showed a total phenol degradation, the highest H2O2 decomposition (85.7%) and more than 80% of TOC removal after 15 h of reaction.

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