Catalytic wet peroxide oxidation (CWPO) of phenol over mixed (Al-Cu)-pillared clays

New mixed (Al-Cu)-pillared clays are prepared from a crude bentonite sample (H) (Tunisia deposit) by two discrete procedures: (a) a classical 'D' method by which Al or (Al, Cu) nitrate solutions, hydrolyzed with NaOH, are added to a 2% clay suspension and (b) a 'P' method where the clay powder is directly dispersed in the pillaring solution. Intercalation reactions are performed at 40 degrees C, with an OH/(Al, Cu) molar ratio equal to 1.5 or 2 and an initial atomic percentage of copper (100 Cu/Al+Cu) of 0, 5 or 10%. Chemical analyses, XRD spectra and surface properties show that clays are intercalated after calcination at 300 degrees C from both preparation procedures. There is increase of the Al content, door and of the BET surface area, the copper content remains quite low whatever the conditions of preparation. Nevertheless, it seems that the copper content resulting from the 'P' method is higher. During phenol oxidation with hydrogen peroxide (CWPO reaction), the copper content and the procedure of preparation significantly influence the catalytic activity. Moreover, the very low copper solubilization proves that copper is certainly associated with alumina at the surface of the catalyst in mixed species intercalated or/and dispersed on the clay surface. (C) 1998 Elsevier Science B.V.