Dispersion and 3-picoline ammoxidation investigation of V2O5/α-Al2O3 catalysts

Abstract

The effect of changing the precursor on the dispersion and 3-picoline ammoxidation activity of various α-Al₂O₃ supported V₂O₅ catalysts has been investigated by the techniques of X-ray fluorescence, AES, SEM, EPR, XRD, oxygen chemisorption at 195 K and ammonia chemisorption at 423 K. The nature of the precursor plays an important role in obtaining a highly selective catalyst for 3-picoline ammoxidation to nicotinonitrile. Using maximum oxygen uptake at 195 K and also surface-specific AES and SEM vanadium(III) acetyl-acetonate derived catalysts were found to give a highly dispersed and highly selective catalyst series for nicotinonitrile production in the title reaction. From AES study the oxygen peak intensity, which also reflects the extent of oxidation of the surface, was found to decrease in the order vanadium(III) acetylacetonate > vanadyl oxalate > ammonia metavanadate. The same trend was also observed in their catalytic activity in 3-picoline ammoxidation. The acidity of various catalysts, measured by ammonia uptake, correlated with their selectivity to pyridine.