Effect of Microwave Irradiation on Catalytic Properties of Vanadium Oxide Nanoparticles Supported by Zirconia and Alumina in Heterogeneous Gas-Phase Oxidation of 3-Picoline to Nicotinic Acid
Direct heterogeneous catalytic oxidation of 3-picoline with air offers an efficient route to nicotinic acid synthesis. By using conventional energy for the reaction, vanadium pentoxide supported by TiO2 (anatase) was found to be the only effective catalytic system. The application of microwave energy creates a unique temperature profile in a catalyst particle allowing the use of a variety of supports (SiO2, Al2O3, and ZrO2) for the V2O5 active component. All compositions show improved kinetic features. A small excess of oxygen and water vapors in the reaction mixture are needed for the catalyst to have enough Brönsted acid sites in addition to the proper redox properties in order to have high activity and selectivity in the environmentally friendly process of nicotinic acid formation.