Reactivity of layered vanadium pentoxide hydrate with ultrafine metal oxide, TiO2 and ZrO2, particles in an aqueous system

Abstract

The interactions between vanadium pentoxide hydrate (V2O5·nH2O) sol and colloid solutions of ultra fine titanium dioxide TiO2 and zirconium dioxide particles ZrO2 were studied. When mixed with an intrinsic V2O5·nnH2O sol, TiO2 particles in the mixed sol are sandwiched by V2O5·nH2O layer sheets to form intercalation compounds. An Interlayer distance of V2O5·nH2O was increased by this treatment and the surface area was also increased from 7.9 m2 g−1 for the V2O5·nH2O to ca. 50 m2 g−1. When the TiO2 sol was contacted with K-type V2O5·nH2O, microporous nature appeared in the sample and the surface area incrased up to ca. 100 m2 g−1. The porous structure was maintained up to 300°C, above which materials were separated into two phases, anhydrous V2O5 and anatase type TiO2. Ultrafine ZrO2 particles were intercalated stoichiometrically in both intrinsic and K-type V2O5·nH2O giving ZrO2-V2O5·nH2O for all the mixing ratios from ZrO2/V2O5 = 5 to 20. Physico-chemical properties were almost unvaried and the materials were nonporous. Their surface areas are around 50 m2 g−1 for the former and around 60 m2 g−1 for the latter. The layered structure was maintained up to 300°C above which the sample was crystallized into ZrV2O7. The reaction temperature is about 150°C lower than that the heated mixture of ZrO2 and V2O5 powders. The electron microscope observations of the prepared materials showed that the number of the stacked layers was decreased from more than 10 sheets for the sample before intercalation to about 2–4 sheets by exfoliation. This indicates that V2O5·nH2O is exfoliated by ion exchangeably reacting to ultrafine titanium oxide and zirconium oxide particles.