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·nH₂O 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 m²g^-1for the V₂O₅·nH₂O to ca. 50 m²g^-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 m²g^-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 m²g^-1 for the former and around 60 m²g^-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.