SYNTHESIS AND CHARACTERIZATION OF PILLARED BUSERITE

Synthetic Na-buserite, a layered manganese oxide formulated as Na4Mn14O26.xH2O, was pillared with polyoxo cations of aluminum known widely as Keggin ions, [Al13O4(OH)24(H2O)12]7+, with a diameter of 8.6 angstrom. The synthetic Na-buserite was first expanded with n-hexylammonium cations to produce hexylammonium ion-expanded buserite. This process expands the buserite interlayer free spacing from 1.94 to 12.94 angstrom, thus allowing subsequent ion-exchange reaction with Keggin ions to proceed. The presence of pillars between the interlayers of the buserite structure was confirmed by X-ray diffraction, thermogravimetric analysis, and surface area measurements. N2 adsorption-desorption studies showed that the Keggin ion-pillared buserites are microporous in nature. Particular interest was focused on the studies of the thermal stability of the various materials in different gaseous environment. By complementary studies between X-ray diffraction and thermogravimetric analysis, the intermediates and the final products of these reactions can be identified.