Cezar Catrinescu

Catalytic wet peroxide oxidation of phenol over Fe-exchanged pillared beidellite

This study presents an evaluation of the catalytic performances of a Fe-exchanged Al-pillared synthetic beidellite for the wet hydrogen peroxide oxidation of phenolic aqueous wastes. The catalyst was prepared by a cation doping technique, its properties being determined by DRX, BET and chemical analysis techniques. All the tests were performed on a laboratory scale set-up. Important factors affecting catalyst activity and phenol removal efficiencies were studied, i.e. the effect of pH, temperature, catalyst concentration and the stability of the catalyst. The experimental results indicate that the use of this catalyst allows a total elimination of phenol and a significant removal of chemical oxygen demand, without significant leaching of Fe ions. Thus, considering the lowest Fe concentrations in solution after oxidation, at pH=5, 50 degrees C, and 180 min. COD removal efficiency of 87.9% was obtained. It was also observed that by using this catalyst, it is possible to extend the range of pH values for which Fenton-type oxidations can occur.

PORTO SANTO CLAYS AS ENVIRONMENTALLY FRIENDLY CATALYSTS FOR THE CONVERSION OF RENEWABLE TERPENE FEEDSTOCKS. LIMONENE AROMATIZATION TO P-CYMENE

A bentonite collected at Serra de Dentro, Porto Santo Island, Portugal was selected as the starting material for the preparation of ion-exchanged clay catalysts. The pristine clay was characterized in terms of chemical composition (XRF), structure (XRD an FTIR spectroscopy), textural properties (nitrogen adsorption), acidity (TG of cyclohexylamine saturated samples) and catalytic activity (limonene conversion). Results show that clays exchanged with acidic cations (Al, Ni) are very active in limonene conversion, but the selectivity for p-cymene is low ( 15 %). In contrast, over the Na-exchanged form, the reaction is slower but the selectivity to p-cymene is significantly increased (around 35 %). The inherent dehydrogenation activity of the SD clay could be considered responsible for this process.