Activation of propane and butanes over niobium- and tantalum-based oxide catalysts

Niobium and tantalum are important elements for the activation of alkanes in the viewpoints of acidic property and the formation of unique mixed metal oxides. And the difference of the ability of alkane activation between niobium- and tantalum-based oxide catalysts is studied. Although hydrated niobium and tantalum oxides show strong acid property, only hydrated tantalum oxide is activated to a solid superacid by the treatment with sulfuric acid, and isomerizes n-butane to isobutane at room temperature. The sulfuric acid treated tantalum oxide activates P-Mo-V heteropolyacid compounds for the selective oxidation of isobutane to methacrolein (MAL) and methacrylic acid (MAA). The difference of ability of alkanes activation between niobium and tantalum is studied by using surface science technique. Mo-V-Nb-Te mixed metal oxide catalysts are active for the ammoxidation of propane to acrylonitrile (AN). However, Mo-V-Ta-Te mixed metal oxide is less active. The effect of catalyst preparation condition is studied. Mo-V-Nb-Te mixed metal oxide catalysts are also active for the oxidation of propane to acrylic acid (AA). (C) 2002 Elsevier Science B.V. All rights reserved.