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

Abstract

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 MoO42- anions. The transformation into MoO42- 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.