Synthesis and characterization of hydroxy-chromium pillared bentonite

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 elimination of water from alcohols. The chromium oligomers used for intercalation were prepared by addition of Na(2)CO(3) to a chromium nitrate solution or chromium chlorite solution and the mixture is heated at 80A degrees C for 36 h. The pillaring clay is obtained by heating intercalated bentonite at 360A degrees C under vacuum. Several Techniques, X-ray diffraction, N(2) adsorption-desorption isotherms and chemical analysis have been used to characterize 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 21 . 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 pillaring increased with the amount of chromium retentions.