Optimization of vanadium oxide catalyst for the oxidation of 3-methylpyridine into nicotinic acid

摘要

Upon modification of V2O5 with SnO2 or ZrO2, increase in the activity and selectivity of the vanadium-oxide catalyst in the vapor-phase oxidation of 3-methylpyridine into nicotinic acid were observed. It was shown that the promoting effects of SnO2 and ZrO2 were the result of increases under their influence of the proton affinity of the vanadyl oxygen and decreases in the enthalpy of deprotonation of the methyl group of the substrate, connected by a nitrogen atom with the Lewis acidic center (vanadium ion). The given characteristics were calculated by the density functional theory quantum-chemical method. Modification of binary V2O5–SnO2 and V2O5–ZrO2–catalysts by TiO2 addition resulted in a further increase in the nucleophility of the vanadyl oxygen and, as a consequence, an increase in the catalytic activity and selectivity for nicotinic acid formation.