MESOSTRUCTURED MIXED METAL Mo-V-Nb OXIDES FOR THE SELECTIVE OXIDATION OF LOWER ALKANES

摘要

Mesostructured Mo-V-Nb oxides were prepared under mild synthesis conditions employing cationic, anionic and alkylamine surfactants. Lamellar, and a mixture of hexagonal and lamellar mesostructures were synthesized for the first time for this system. The formation of these mesostructures was partially explained by charge matching considerations at the inorganic-organic interface. Incomplete condensation of the inorganic framework as well as the redox reactions taking place during template removal lead to poor thermal stability of these mesophases. Air-calcined samples showed the presence of dense phases proposed as catalytically active for propane ammoxidation to acrylonitrile. Catalytic studies of propane ammoxidation showed that mesostructured Mo-V-Nb oxides displayed conversions of ～66% and yields to acrylonitrile and acetonitrile of ～17% and ～32 %, respectively. The complete removal of template as well as the improvement in thermal stability of these novel transition metal oxide mesophases is expected to lead to further improvement in its catalytic performance for selective alkane oxidation.