Interlayer functionalization of phyllosilicates.

Tetraalkylammonium cation intercalation into smectites was found to be a useful tool for the study of many aspects of smectite chemistry, including the determination of their internal surface areas and the identification of the mineral composition of Alberta oil sands bitumen. The adsorption of aromatic molecules to these organoclays has given useful insights about the nature of the interlamellar pore systems of these compounds. The grafting of organic moieties to the interlayer surface of montmorillonite was achieved by the reaction of the acidified clay with 3-chloropropyltrimethoxysilane. Nucleophilic substitution of the Cl for chelating functionalities (SH and SCH$\sb2$CH$\sb2$SH) has resulted in highly effective heavy metal adsorbents, particularly for Pb and Hg. The adsorbents could be easily regenerated by leaching out the metal with HCl. Similar materials were prepared using the layered silicates magadiite and kenyaite, but were found to be ineffective for the removal of metal ions from solution because of the congestion of the interlamellar region of these minerals by the organic functionalities which has prevented the access of the metal ions to the chelating sites. Alcohols and diols were found to condense onto the the interlamellar silanols of H-magadiite and H-kenyaite upon thermal treatment. The techniques used to characterize these compounds provided strong evidence of the formation of Si-O-C linkages between the mineral template and the organic groups. The nanocomposites thus formed were found to be stable to well beyond 400$\sp\circ$C, but did not show appreciable microporosity. The grafting interlamellar region of these silicates, whose crystal structures are still unknown. The preparation of clay-based catalysts for nitric oxide decomposition was attempted by the cointercalation of organic and metal cations into montmorillonite and by the doping of Al-pillared montmorillite by metal ions. The resulting compounds were found to promote the ortho nitrosylation of phenol in the presence of NO gas, but only in very low yield (3%). Static variable temperature studies have failed to show any catalytic decomposition of nitric oxide in the presence of these materials