Hydrothermal Synthesis of Monoclinic CrVO4 Nanoparticles and Catalytic Ammoxidation of 2-chlorotoluene

Vanadium-chromium composite oxides have held much interest due to their distinctive catalytic properties, which depend on their morphology and crystal structure. During the hydrothermal synthesis, reducing agents play an important role in controlling the morphology and the crystal structure of vanadium-chromium oxides. In this work, nanocrystalline chromium vanadate (CrVO4) were prepared by a simple one-pot hydrothermal method based on the reaction between V2O5 and CrO3. Three different CrVO4 crystal structures, including orthorhombic CrVO4, monoclinic CrVO4, and mixed-phased-CrVO4 were obtained by using different reducing agents. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed that nanocrystalline monoclinic CrVO4 was obtained using tartaric acid as the reducing agent. Catalytic properties of nanostructured CrVO4 were investigated for the vapor phase ammoxidation of 2-chlorotoluene to 2-chlorobenzonitrile. The monoclinic CrVO4 nanostructures exhibited excellent catalytic performance due to the proper distribution of V-O-Cr bond. It was one of the most efficient binary catalysts for such vapor phase ammoxidation processes to the best of our knowledge, and may have great potential for the ammoxidation of halogen-substituted toluenes. [GRAPHICS]