Investigations Of V2O5—Based LPG sensors

Abstract

Sensor characteristics of V2O5 dispersed on oxide supports such as Al2O3, TiO2 and ZrO2 with respect to various gases and vapours including liquefied petroleum gas (LPG) have been investigated. Of all the systems studied, 20 mol% V2O5 dispersed on ZrO2 shows the highest sensitivity for LPG, the log sensitivity-log concentration (in ppm) plots being linear up to 1000 ppm or more. The sensitivity is not affected by humidity or recycling. Addition of P2O5 to V2O5 however destroys the sensitivity. Considering all aspects, 20 mol% V2O5/ZrO2 is Suggested for use as a practical LPG sensor. ESR spectroscopy indicates the formation of V4+ species on exposure of V2O5/ZrO2 or TiO2 to LPG. In-situ high-temperature x-ray diffraction measurements show the formation of an unusual monoclinic form of VO2 on exposure to LPG at 625 K which gets oxidized back to V2O5 on exposure to air.