Abstract
The oxidation state and local geometry of tellurium in MoVTeNbO catalysts used in the ammoxidation or oxidation of propane were characterized by X-ray absorption, Mössbauer, and X-ray photoelectron (XPS) spectroscopies. The results obtained by Mössbauer, and XPS spectroscopies showed that the catalysts contained Te (IV) in the bulk and mainly Te (VI) at the surface. X-ray absorption fine structure (EXAFS) measurements allowed to determine that the tellurite entities corresponded to TeO 4E trigonal bipyramid in the hexagonal phase and to TeO 3E somewhat distorted trigonal pyramid in the orthorombic one. The completely determined environment appeared to correspond in both phases to crystallographic sites in hexagonal channels. These results allowed to determine the stoichiometries of the two phases which are TeM 3O 10 for the hexagonal phase and Te 2M 20O 57 for the orthorombic phase (M=Mo, V, Nb). 125Te Mössbauer isomer shift and pre-peak surface of the X-ray absorption spectra of the Te L III-edge have been correlated and contributions of the Te(5s) and Te(2p 3/2) to the structure have been analyzed.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
