Pillared titanates: Titanium oxide of high surface area and porosity

Abstract

Pillaring layered titanates with robust polyoxometallic oligomers is a route to prepare microporous titanium oxide. In addition to using the organic intercalated compounds as precursors, the pillaring reaction on this layered metal oxide with a high charge density was facilitated by using layered titanate of low crystallinity and small particle size, which was achieved by hydrolyzing TiCl 4 in strong alkaline solution. The resultant compound had a formula close to that of layered trititanate, NaHTi 3O 7·2H 2O. Both aluminium Keggin ions, formulated as [Al 13O 4(OH) 24(H 2O) 12] 7+, and hydroxyzirconium tetramer cations, formulated as [Zr 4(OH) 8(H 2O) 16] 8+, were introduced into the interlayers of this layered titanate. The layered structure was retained up to 600°C for the alumina-pillared derivative, but only to 500°C for the zirconia-pillared derivative. The pillared samples had BET surface areas ⩾ 150 m 2/g and contained both micro- and mesopores. Many of the physicochemical properties of the compounds before and after pillaring were compared. Most of the characteristic properties of TiO 2 were retained on the pillared derivatives.