Multi-component fitting XAFS analysis of molybdate species during catalyst preparation by the molten salt method

The goal of the present study was to elucidate the formation mechanisms of highly dispersed catalysts by the molten salt method. For this purpose, multi-component fitting Mo K-edge EXAFS analysis was applied to the structure of molybdate catalysts prepared in KNO₃ and NaNO₃. The analysis revealed that MoO₃ dissolved in molten salts was at first transformed into polymolybdate anions and finally into MoO₄^2- anions. The transformation into MoO₄^2- anions took place at a lower temperature when NaNO3 was used as molten salt than KNO₃. In contrast, polymolybdate anions were stable even at higher temperature when ZrO₂ was added as a support of molybdate.