# Synthesis and Investigation of Vanadium-Based Catalysts for the Oxidation of 4-Methylpyridine to Isonicotinic Acid

## TL;DR

This study explores vanadium-based catalysts for efficiently converting 4-methylpyridine into isonicotinic acid through selective oxidation.

## Contribution

The paper introduces a novel V-Ti-Cr catalyst that achieves high conversion and selectivity in the oxidation of 4-methylpyridine.

## Key findings

- The V-Ti-Cr catalyst achieves 86.88% conversion and 73.06% selectivity at 320 °C.
- Higher temperatures increase conversion but also promote undesired deep oxidation reactions.
- V-Ti shows moderate stable performance, while V-Cr is less efficient.

## Abstract

The study investigates the catalytic activity of vanadium-containing catalysts in the selective oxidation of 4-methylpyridine (4-MP) in the gas phase. V-Cr, V-Ti, and V-Ti-Cr catalysts were synthesised and studied. The phase composition and structural features of the catalysts were determined by X-ray diffraction (XRD) and Raman spectroscopy, and their thermal stability was investigated using thermogravimetric analysis (TGA/DTA). Textural characteristics were evaluated by low-temperature nitrogen adsorption–desorption (BET, BJH), surface morphology was studied using scanning electron microscopy (SEM), and the distribution of elements was investigated using energy-dispersive X-ray spectroscopy (EDX). The chemical composition of the catalysts was determined using inductively coupled plasma atomic emission spectrometry (ICP-OES) and catalytic activity was evaluated in the selective gas-phase oxidation reaction of 4-methylpyridine in the temperature range 280–380 °C. It was found that an increase in temperature is accompanied by an increase in the conversion of 4-methylpyridine, but at the same time, deep oxidation reactions intensify. The best result is achieved on the V-Ti-Cr catalyst, for which the conversion of 4-MP reaches 86.88% and the selectivity is 73.06% at 320 °C. However, V-Ti provides moderate stable performance, while V-Cr demonstrates relatively low efficiency. Thus, it can be concluded that the nature of the temperature dependence of 4-methylpyridine conversion reflects the different nature of the active centres and their stability.