Oxidation of Dodecane on Vanadium-Molybdenum Catalysts

The catalytic oxidation of dodecane with air oxygen on individual and mixed vanadium-molybdenum (1 -x)V2O5 center dot xMoO(3) oxide is studied over a temperature range of 250 to 400 degrees C. It is shown that oxidation of dodecane to organic acids at 250 degrees C produces undecylic acid C11H26COOH and carbon oxides, as products of the subsequent oxidation of formic acid. The most effective catalyst is a mixed oxide containing 75 mol % MoO3 and 25 mol % V2O5. At 275-300 degrees C, this catalyst provides the maximum yield of acids and a relatively low fraction of complete-oxidation products. Above 250 degrees C, a mixture of acids and carbon oxides is formed, the yield of which increases with the temperature up to 300 degrees C. As the temperature is increased still further, the yield of acids decreases due to their subsequent oxidation. The catalytic oxidation is accompanied by changes in the phase composition, morphology, and degree of crystallinity of the mixed-oxide catalysts. A possible mechanism of the catalytic process is considered.