Electron spin resonance of vanadium pentoxide molybdenum trioxide catalysts

Abstract

X-ray, infrared, and electron spin resonance (ESR) studies were made on molybdenum trioxide catalysts doped with 0.25, 0.5, 2.0, 5.0, 10.0, and 20% by weight vanadium pentoxide. X-ray diagrams indicate the existence of two kinds of patterns for catalysts containing more than 2% V2O5. All the samples produced ESR signals, including pure V2O5. For low dopant concentrations the signals were well resolved, and the paramagnetic center was identified as the VO2+ ion in the unit structure VO2+5O2−. The resonance lines increased in width as the dopant concentration was increased to 10%, and only a single broad line existed for 20% V2O5 or pure V2O5.