The effect of Fe/Cu ratio in the synthesis of mixed Fe,Cu,Al-clays used as catalysts in phenol peroxide oxidation

Mixed Fe,Cu,Al-clays (Fe,Cu,Al-MM) were prepared from Ca-montmorillonite (Mukhortala, Buryatia) at OH/(Fe + Cu + Al) 2.4 and Al/(Fe + Cu) 10/1. Effect of Fe/Cu ratio of Fe,Cu,Al-containing pillaring solution on structural properties of Fe,Cu,Al-MM was examined. Characterization studies were performed by use of XRD, FTIR, DR-UV–vis and N2-adsorption/desorption analysis. The increase in copper loading leads to the decrease in total surface area, micropore volume and interlay distance of Fe,Cu,Al-MMs. It was found that the decrease in Fe/Cu ratio is favourable for the formation of oligomeric iron species. The relationships between preparation conditions, iron state, catalytic activity and stability to leaching were revealed in wet phenol oxidation with H2O2. The introduction of copper ions results in catalytic reaction acceleration that was interpreted in terms of the increase of radical generation rate.