Datensatz

Zusammenfassung

The in situ microwave cavity perturbation technique was used to study the complex permittivity and conductivity of polycrystalline α-V₂O₅ in a tubular reactor under reactive high-temperature conditions with a TM₁₁₀ cavity resonating at 9.2 GHz. The sample was investigated at 400 °C in flowing air and air/n-butane mixtures while simultaneously measuring the total oxidation products CO and CO₂ by gas chromatography. The V₂O₅ powder was identified as an n-type semiconductor and the dynamic microwave conductivity correlated well with the near-infrared (NIR) absorption assigned to V3d¹ band gap states. Correlations between catalytic performance, real and imaginary parts of the permittivity, and NIR absorption allowed the differentiation between bulk and surface contributions to the charge transport in reactive atmospheres. The stability of the crystalline bulk phase was proven by in situ powder X-ray diffractometry for all applied testing conditions.