A facile solvent-deficient, one-pot synthesis of a thermally stable silica-doped alumina having a large pore volume and large bimodal pores has been developed. Silica doped alumina (BSDA) was synthesized by adding 5 wt% silica from TEOS to aluminum isoproxide (AIP) and 1:5 mole ratio AIP to water. The addition of silica greatly increased the stability of the gamma alumina phase to 1200�C while maintaining high surface area, large pore volume and large pore diameter. The silica doped alumina structure was studied by in situ-high temperature XRD (HTXRD) powder diffraction, surface analysis (BET), thermo-gravimetric analysis (TGA), solid-state nuclear magnetic resonance (NMR), and transmission electron microscopy (TEM). Results reveal that Si enters tetrahedral vacancies sites in the defect spinel structure of ?-alumina substantially increasing its thermal stability and preventing collapse of the porous structure at high temperatures. It is also evident from our data that alumina cations are not replaced by silica cations; thus, the postulated structure is very different from that previously reported.In addition, result show that 5% BSDA is in gamma phase at 1200oC and has a surface area of 160 m2/g, a pore volume of 1 cm3/g, and bimodal pore diameters of 22.5 and 52 nm at 1100 oC.

Facile one-pot synthesis of a thermally stable silica-doped alumina having a large pore volume and large bimodal pores

247th National Meeting (2014)

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