PILLARED CLAYS PREPARED FROM THE REACTION OF CHROMIUM ACETATE WITH MONTMORILLONITE

Refluxing chromium (III) acetate with a Na+-montmorillonite suspension gives rise to the intercalation of linear Cr(III) polyhydroxo-acetate oligomers. Thermally stable chromia pillared montmorillonite materials are obtained upon calcination under ammonia up to 625-degrees-C, and basal expansions up to 6 angstrom are maintained. The porous materials retain high surface areas (366-464 m2 g-1), a micropore volume of 0.1 cm3 g-1 and narrow pore size distributions centered between 7.5 and 12 angstrom. The most thermally stable materials in air were those prepared under ammonia at 625-degrees-C, containing NH4+ as the exchangeable ion.