Synthesis and Monitoring of MoVSbNbO Oxidation Catalysts Using V K and Sb L1-Edge Xanes Spectroscopy

Pure M1 phase of MoVSbNbO catalysts have been prepared using the slurry method with two heat treatments in air around 300 degrees C and under N-2 at 600 degrees C followed by a final selective dissolution of the M2 phase formed concomitantly. The evolution of the oxidation state of antimony during the various steps of the preparation has been studied using V K and Sb L-1-edge Xanes spectroscopy. The results showed that the mean valence state of these elements changed several times and in a significant way during the various steps. These results along with those obtained using other characterization techniques allowed to identify several key parameters whose influence on the composition of the final catalyst and on its catalytic properties in propane oxidation to acrylic acid are discussed.