卷 66, 编号 2 (2025)

Highly porous SiO₂ supports with the MCM-41 structure were synthesized by template method. Pt–Ga catalysts for propane dehydrogenation were obtained using the impregnation method. The structure of the synthesized samples was studied by low-temperature nitrogen adsorption and X-ray phase analysis (XRD), and the properties of catalyst reduction were studied by temperature-programmed reduction in hydrogen (TPR-H₂). The catalytic properties were studied in the reaction of propane dehydrogenation, and the influence of hydrogen in the composition of the reaction mixture was studied. It has been shown that the addition of hydrogen into the reaction mixture leads to an increase in the stability and activity of platinum catalysts.

The article is devoted to the experimental and theoretical study of complex oscillations during ethylene oxidation on the nickel foil. Mathematical model was based on the 14-stage mechanism of reaction including the stages of oxidation and reduction of the Ni catalyst. An essential condition for the occurrence of an oscillatory behavior of the system was the adsorption of C₂H₄ and CO from the mobile pre-adsorption state. It was shown that for real values of the parameters, the mathematical model can describe both regular and irregular oscillations, as well as the “mixed-mode” oscillations observed in the experiment. For the first time oscillations with different properties and distinct mechanisms of their occurrence were detected in the same model. It was demonstrated that oscillations occurred as a result of a strong dependence of the reaction rate on the concentration of active sites both due to a variation in the concentration of the surface oxide or the surface carbon.

This article presents studies on the catalytic, peroxidase-like properties of silver nanoparticles (Ag NPs) immobilized in polymethacrylate matrix (PMM). Ag NPs were prepared by thermal reduction of silver cations pre-immobilized in PMM. The morphology of the nanocomposite was studied using scanning electron microscopy, and the average size of the synthesized individual spherical nanoparticles was 18 ± 5 nm. It was demonstrated that silver nanoparticles immobilized in a polymethacrylate matrix (PMM-Ag⁰) exhibit pronounced peroxidase-like activity in the oxidation reaction of the chromogenic substrate – indigocarmine in the presence of H₂O₂. The Michaelis–Menten model was used to assess the kinetic parameters of the reaction. The values of Michaelis constant (K_m) observed for indigocarmine and H₂O₂ (0.1 mM and 1.0 mM, respectively) show strong affinity of the substrates to silver nanoparticles in PMM.

The X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR) spectroscopy were used to study the features of anchoring of the [Ir₂(COD)₂Cl₂] complex on the surface of modified silica gel L–SiO₂ (where L is NC₅H₅–CH₂–CH₂–, N(CH₃)₂–CH₂–CH₂–CH₂–, NH₂–C₃H₆–) depending on the nature of the linker and the conditions of preparation of the systems. The catalytic activity was tested in reactions of gas-phase selective hydrogenation of propylene with parahydrogen (p-H₂). According to the XPS data, a single-site iridium catalyst is prepared in all cases. Analysis of the XPS spectra indicates the possibility of anchoring the complex through one of the Ir atoms while preserving the dimer. It was shown that at different durations of interaction of the iridium complex solution with modified NH₂–C₃H₆– silica gel approximately the same amount of the complex is anchored, but the nature of the complex coordination changes. For the sample obtained by long-term interaction of the complex solution with the modified support (24 h), a high increase in the NMR signal was observed at 60°C, while in the case of the sample prepared by short-term interaction (1 h), the signal increased with a rise in temperature to 80°C.