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 s ample (H) (Tunisia deposit) by two discrete procedures: (a) a classica l 'D' method by which Al or (Al, Cu) nitrate solutions, hydrolyzed wit h NaOH, are added to a 2% clay suspension and (b) a 'P' method where t he clay powder is directly dispersed in the pillaring solution. Interc alation reactions are performed at 40 degrees C, with an OH/(Al, Cu) m olar ratio equal to 1.5 or 2 and an initial atomic percentage of coppe r (100 Cu/Al+Cu) of 0, 5 or 10%. Chemical analyses, XRD spectra and su rface 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 r emains quite low whatever the conditions of preparation. Nevertheless, it seems that the copper content resulting from the 'P' method is hig her. During phenol oxidation with hydrogen peroxide (CWPO reaction), t he copper content and the procedure of preparation significantly influ ence the catalytic activity. Moreover, the very low copper solubilizat ion proves that copper is certainly associated with alumina at the sur face of the catalyst in mixed species intercalated or/and dispersed on the clay surface. (C) 1998 Elsevier Science B.V.