Preliminary results on the properties of pillared clays by mixed AlCu solutions

Three crude bentonites samples from USA (W), Tunisia (H) and Algeria (MR) have been used in order to prepare Cu-exchanged and new mixed AlCu pillared clays by three methods (i) a classical ‘dilute suspension and solution’ method by adding the nitrate pillaring solution to a 2% clay suspension, (ii) a ‘powder in solution’ method where the clay powder is dispersed in the pillaring solution and (iii) a ‘concentrated slurry’ method in which a dialysis bag containing clay-water slurry (33% w/w) is placed in the pillaring solution. These three methods are called D, P and CS respectively. Pillaring reactions was performed at 40°C with a OH/(Al + Cu) molar ratio (R) equal to 2 and at Cu/(Al + Cu) ratio of 0, 5 and 10%, respectively. Chemical analysis, X-ray diffraction, N2 BET surface area and cation exchange capacity measurements were carried out to characterize the pillared materials. The results show that after calcination at 300°C, the three pillaring methods lead to a d001 peak at about 1.8 urn which subsists after one year ageing, and which remains at 1.6 nm even at 800°C for some samples. Catalytic tests in oxidation reaction of phenol by H2O2 in diluted aqueous solution performed at room temperature show an interesting activity of the Cu-clays.