Current research on the synthesis of isonicotinic acid (INA) has focused on the development of catalysts by mixing transition metal oxides such as vanadium, titanium and zirconium in the desired molar ratio. These materials have good catalytic activity (CA) but have drawbacks, including low resistance to deactivation and limited ability to control reaction selectivity. In the present study, two- and three-component catalysts containing vanadium were successfully synthesized and their compositions and properties were studied. The experimental results showed that the efficiency of V-Ti-Mn-O catalyst was superior to V-Ti-O. Selectivity analysis showed that V-Ti-Mn-O was the most efficient catalyst, reaching a maximum value of 67.17% at 320 °C. Scanning electron microscope (SEM), Raman spectroscopy and X-ray diffraction (XRD) were used to characterize the catalysts. The corresponding experimental results showed that the superior performance of the V-Ti-Mn-O catalyst was attributed to both the smaller size of the catalyst particles and their more uniform distribution. In the oxidation of 4-methylpyridine (4-MP), the V-Ti-O catalyst showed lower CA and stability compared to the V-Ti-Mn-O catalyst, which can be attributed to its limited CA and potential deactivation at higher temperatures, probably due to excessive oxidation.

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.

This paper presents the results of an investigation into the catalytic activity and selectivity of rhodium-based catalysts supported on natural zeolite clinoptilolite from the Shankanai field (Kazakhstan) in the dehydrogenation of light alkanes from associated petroleum gas (APG). Three modifications of the catalyst have been studied: basic 1%Rh/HCpt, modified with tin 1%Rh/10%SnO/HCpt, and combined with additives of tin and potassium 1%Rh/10%SnO/5%K₂O/HCpt. It has been shown that the addition of tin contributes to increased thermal stability and a decreased coking rate, while the addition of potassium suppresses side reactions (cracking and isomerization), increasing the selectivity for olefins. The highest yield of olefins (~30%) is achieved with the 1%Rh/10%SnO/5%K₂O/HCpt catalyst in the presence of water vapor. Using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), improved distribution of active components and reduced catalyst deactivation have been confirmed. The obtained data demonstrate the potential of the developed systems for the efficient processing of APG and the selective synthesis of olefins.

The selective conversion of high-molecular-weight paraffins (C₂₀–C₄₀) into linear alpha-olefins is often hindered by severe diffusion limitations and secondary over-cracking. This study addresses these challenges by transforming low-value natural minerals into sophisticated catalytic systems. We present a “top-down” engineering strategy for designing hierarchical catalysts based on natural Kazakhstani clinoptilolite. The multi-stage modification involves synergistic demineralization and precision chelation (EDTA, sulfosalicylic acid) to generate a tailored mesoporous architecture. This framework serves as a host for the sub-nanometric immobilization of Keggin-type heteropolyacids (PW₁₂, PMo₁₂), ensuring optimal active-phase dispersion. The innovative dual-step modification successfully bypassed the “micropore barrier”, creating a high-surface-area hierarchical network that facilitates the transport of bulky paraffinic molecules. Precise localization of heteropolyacid clusters within the created mesopores resulted in the formation of superstrong Lewis acid sites, as confirmed via temperature-programmed ammonia desorption. These sites triggered a highly efficient monomolecular beta-scission mechanism, suppressing undesirable hydrogen transfer reactions. The resulting catalysts achieved a breakthrough in technical paraffin cracking, delivering a 70% liquid product yield with an unprecedented >50% selectivity toward the C₇–C₁₄ α-olefin fraction. This work demonstrates a sustainable pathway for upgrading natural zeolites into high-performance, green catalysts that rival expensive analogs in precision and efficiency.

The selective gas-phase oxidation of γ-picoline (γ-P) to isonicotinic acid (INA)—a key precursor for the anti-tuberculosis drug isoniazid—was investigated over a V–Mn oxide catalyst as a solvent-free, waste-minimizing alternative to conventional liquid-phase synthesis routes. XRD and Raman spectroscopy confirmed the formation of a stable manganese vanadate crystalline phase with a high concentration of terminal vanadyl groups (V=O), providing well-defined redox-active sites. Water vapour proved essential for sustainable process performance: at an optimal H₂O/substrate molar ratio of 98, γ-picoline conversion reached 94.8% with INA selectivity of 86.5%, eliminating the need for hazardous solvents or additives. NH₃-TPD and kinetic analysis revealed that water vapour acts as a competitive adsorbent at vanadium Lewis acid sites, accelerating target product desorption and suppressing deep oxidation to COx—directly reducing carbon waste. Long-term stability was assessed over 96 h of continuous operation: the 23.4% decline in specific surface area correlated with an equivalent reduction in total acidity, while pore diameter expansion from 2.07 to 3.25 nm mitigated diffusion limitations, partially compensating for deactivation. These findings establish the V–Mn oxide system as a promising green catalytic platform for upgrading petrochemical fractions into high-value pharmaceutical intermediates with reduced environmental impact.

Catalysts based on vanadium pentoxide modified by Ti, Sn, Zr and W oxides were tested in the oxidative ammonolysis of 4-methylpyridine. The role of the main process parameters such as temperature, the ratio of the initial components in the conversion of the methyl group to the nitrile one, and the optimal conditions for the oxidative ammonolysis of 4-methylpyridine were determined. It is determined that the V-Ti-Zr-O-catalyst and the sample containing 9% of tungsten oxide are superior in catalytic activity to the V-Ti-Zr-Sn-O contact. Conditions that ensure a high selectivity for the formation of 4-cyanopyridine were found. The highest yield of the target product (85-86%) was obtained on V-Ti-Zr-W-O at 270 °C, and the yield of 4-cyanopyridine was 87.5% at 310° C on the V-Ti-Zr-Sn-O catalyst. The phase composition and structural changes occurring in modified vanadium oxide catalysts have been studied. It is determined that mixed V-Ti-Zr-Sn-O and V-Ti-Zr-W-O catalysts contain ZrV2O7, the monoclinic modification of ZrO2 (baddeleyite), TiO2 (anatase), SnO2, WO3, and V2O5. In catalysts, it can exist in small amounts as a separate VO2 phase. The V-Ti-Zr-W-O catalyst showed the best catalytic properties. It has highactivity and selectivity towards 4-cyanopyridine.