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. nH(2)O) sol and colloid solutions of ultra fine titanium dioxide TiO2 and zirconium dioxide particles ZrO2 were studied. When mixed with an intrinsic V2O5. nnH(2)O so l, TiO2 particles in the mixed sol are sandwiched by V2O5. nH(2)O layer she ets to form intercalation compounds. An Interlayer distance of V2O5. nH(2)O was increased by this treatment and the surface area was also increased fr om 7.9 m(2) g(-1) for the V2O5. nH(2)O to ca. 50 m(2) g(-1). When the TiO2 sol was contacted with K-type V2O5. nH(2)O, microporous nature appeared in the sample and the surface area incrased up to ca. 100 m(2) g(-1). The poro us structure was maintained up to 300 degreesC, 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. nH(2)O giving ZrO2-V2O5. nH(2)O for all the mixing ratios from ZrO2/V2O5 = 5 to 20. Physico-chemical properties were almost unvaried and t he materials were nonporous. Their surface areas are around 50 m(2) g(-1) f or the former and around 60 m(2) g(-1) for the latter. The layered structur e was maintained up to 300 degreesC above which the sample was crystallized into ZrV2O7. The reaction temperature is about 150 degreesC lower than tha t the heated mixture of ZrO2 and V2O5 powders. The electron microscope obse rvations of the prepared materials showed that the number of the stacked la yers was decreased from more than 10 sheets for the sample before intercala tion to about 2-4 sheets by exfoliation. This indicates that V2O5. nH(2)O i s exfoliated by ion exchangeably reacting to ultrafine titanium oxide and z irconium oxide particles. (C) 2001 Kluwer Academic Publishers.