Rezumat
Chromium pillared clays, in particular, have attracted the researchers attention after being tested as catalyst in a wide range of reactions, like catalytic conversion of hydrocarbons, ester formation and elimina- tion of water from alcohols. The chromium oligomers used for intercalation were prepared by addition of Na2CO3 to a chromium nitrate solution or chromium chlorite solution and the mixture is heated at 80°C for 36h.The pillaring clay is obtained by heating intercalated bentonite at 360°C under vacuum. Several Tech- niques, X-ray diffraction, N2 adsorption-desorption isotherms and chemical analysis have been used to char- acterize and to compare the properties of the materials synthesized. Our study consists in determination of the influence of the intercalated OH-Cr group on the structure of Tunisian bentonite. The results showed that the interlamellar distances of pillared bentonite ranged from 17 to 21Å. In addition, the synthesized clays exhibit increased BET surface areas and higher micro pore volumes compared with unmodified clay. On the other hand, the micro pore surface area, the micro pore volume and the d (001) spacing after pillar- ing increased with the amount of chromium retentions.