Abstract:

Liquid phase oxidation of 4-methylpyridine(4-MP) was carried out under mild reaction conditions over mesoporous Co-MCM-41 catalysts using aqueous hydrogen peroxide(30%) as oxidant and acetic acid as solvent without adding any initiator. The catalysts exhibited high substrate conversion and good product isonicotinic acid(4-PCA) selectivity. Recycling of the catalyst indicates that the catalyst can be used for a number of times without losing its activity significantly. The effects of solvent, reaction time, catalyst concentration, and reaction temperature on the catalyst performance were examined in order to optimize the conversion of 4-methylpyridine and the selectivity of isonicotinic acid. A 91.4% selectivity to isonicotinic acid was obtained at 96.5% conversion of 4-methylpyridine under the optimum reaction conditions:m(4-methyl pyridine)∶m(catalyst)=10∶1, V(4-methyl pyridine)∶V(acetic acid glacial)=1∶10, reaction temperature=363 K, reaction time=6 h. The reaction mechanism is proposed based on the results.

Key words: Co-MCM-41, catalytic oxidation, methyl pyridine, isonicotinic acid