Synthesis, characterization, and properties of pillared layered metal oxides and phosphates

Layered materials are a unique as well as versatile class of compounds which by themselves can act as catalytic supports and ion exchange materials. They are two-dimensional compounds with their layers typically held together by either-ionic or van der Waals interactions. It is the weak cohesive interactions between the individual layers which allows for the unique chemistry of these materials: i.e. their ability to incorporate guest molecules or clusters into their interlayer regions. Once intercalated or exchanged in-between the layers of the host compound, certain types of guest molecules can convert the two-dimensional structure to a three-dimensional structure with new properties.; In the following, three types of layered materials will be investigated: phyllosilicates, titanates, and zirconium bismonohydrogen phosphate (ZrP). Synthesis methods to pillar these compounds using inorganic polyatomic clusters, which are used to create porous materials that can be used as either catalyst or ion exchanges, will be investigated as well as the characterization of these new compounds. Also under study will be new ways at further functionalizing the final pillared products to enhance existing characteristics or create new ones.; In the case of aluminum pillared montmorillonite, thermally stable Bronsted acid sites can be incorporated onto the aluminum oxide pillars by the reaction of the pillared compound with solutions containing phosphate. This is evidenced by MAS-NMR and IR studies of pyridine adsorbed onto the phosphated material. The thermal stability of these incorporated phosphate groups is quite similar to the phosphate groups found in silica pillared zirconium phosphate which was also examined. However, the montmorillonite and ZrP materials differ not only in the type of pillaring species but also in pillar density which is a function of layer charge. Ideas of how layer charge will affect the distribution of pillars in a material was examined using a series of layer titanium oxides which possess increasing layer charge while maintaining similar structural properties. The results of this study will be presented. Finally, it will be shown that the ion exchange properties of a layered titanate can be controlled by slight alterations in the synthesis procedure.