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

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.