Preparation of Phase-Pure M1 MoVTeNb Oxide Catalysts by Hydrothermal Synthesis—Influence of Reaction Parameters on Structure and Morphology

摘要: This work presents a detailed investigation of the preparation MoVTeNbO x catalysts by hydrothermal synthesis. Phase-pure synthesis M1 has been achieved applying metals in molar ratio Mo/V/Te/Nb = 1/0.25/0.23/0.12. Raman, UV/Vis spectroscopy, and SEM/EDX analysis show that elements are inhomogeneously distributed initial suspension is formed after mixing metal salts an aqueous medium. Iso- heteropoly anions molybdenum, free telluric acid as well supra-molecular polyoxometalate clusters observed solution, whereas all have found precipitate. Complete rearrangement molecular building blocks under conditions essential for formation phase-pure materials. Optimized with respect to temperature time result precursor consisting nano-structured characterized extended periodic organization [001] direction fairly homogeneous distribution elements. Residual ammonium containing species phase mixtures during subsequent crystallization heat treatment inert gas. exhibits distinct degree flexibility chemical composition becomes obvious incorporating Nb not exclusively into pentagonal bi-pyramidal units, but also octahedral coordinated positions shown EXAFS. Anisotropic growth needle-like crystals final performed at 873–923 K atmosphere disclosing potential method control catalytic properties catalysts.