Vol 59, No 5 (2025)

Modified lignosulfonates were studied as a basis for multifunctional sulfo-cationic catalysts applicable in chemical technology for basic organic and petrochemical synthesis. Using the example of the cyclotrimerization reaction of propanal, it was shown that high catalytic activity is due to the multifunctional nature of the catalyst. It has been established that the catalysts have high thermal stability and retain their activity in water-alcohol environments. In the reactions of isobutene hydration, tert-butyl alcohol dehydration, and alkyl tert-butyl ester synthesis, lignosulfonate systems demonstrate competitiveness compared to traditional sulfo-cations, combining high activity with increased stability. Based on the analysis of water distribution along the reactor height, a strategy for layer-by-layer loading of catalysts was proposed, which made it possible to increase alcohol conversion from 70 to 83% and reduce the load on the rectification system. To increase the service life of catalysts, a modernized technological scheme has been proposed, including a stage of preliminary purification of raw materials from transition metal ions.

This review examines current issues related to the replacement of natural rubber in rubber products. The first section of the review compares the structure and properties of natural rubber and synthetic isoprene rubber, highlighting the differences between them. The main reasons for the high cohesive strength of natural rubber are shown. The second section examines the main methods of replacing natural rubber in rubber compounds and provides an analysis of them, showing the advantages and disadvantages of each method. Based on the analysis, it was found that the most accessible and cost-effective way to replace natural rubber is to create a synthetic material that will make rubber compounds and rubbers similar in properties to natural rubber. An analysis was conducted of methods for increasing the cohesive strength of synthetic isoprene rubber, which will allow the creation of a material with properties similar to those of natural rubber, and the most effective and affordable method was determined – using a mixture of polymers. It has been shown that combining synthetic polyisoprene with polyethylene and other polymers improves the basic properties of elastomeric materials based on synthetic isoprene rubber to the properties of elastomeric materials based on natural rubber, in particular, the cohesive strength of the rubber compound, modulus, and fatigue characteristics of rubbers.

A theoretical analysis was performed of various options for organizing coupled extraction-re-extraction processes in a cascade of mixing-settling extractors: schemes in which the extractant phase passes through all stages of extraction, then through all stages of re-extraction, and schemes of the processes when the flow of this phase circulates between the stages of extraction and re-extraction in separate groups of cascade extractors (schemes of supported free liquid membranes). It has been established that supported free liquid membrane schemes provide a higher degree of extraction and better separation quality.

The review presents literature data on methods for synthesizing hexaf luoroethane, a gaseous fluorine carrier for silicon etching in the semiconductor industry – catalytic fluorination of fluorochlorocarbons with hydrogen fluoride; fluorination with fluorine, variable-valence metal fluorides, uranium hexafluoride, ethane, ethylene, fluoroethanes, fluoroethylenes, fluorochloroethanes, and fluorochloroethylenes; fluorination of carbon with fluorine; pyrolysis of perfluorocarbons; electrochemical methods. The advantages and disadvantages of these methods are presented. Methods for purifying hexafluoroethane from impurities formed during synthesis are also considered, including decantation, neutralization, rectification, adsorption, etc. Methods for studying the composition of hexafluoroethane are considered, including gas chromatography, spectral methods, and determination of gas moisture and acidity.

This review article describes modern methods for modeling the kinetics of high-temperature oxygen-free conversion of methane to acetylene. Published studies on both fundamental aspects of the reaction mechanism and applied methods of computer modeling are analyzed. Particular attention is paid to modern computational methods, such as numerical methods for solving systems of differential equations, quantum chemical methods, and machine learning methods. The influence of key process parameters on the yield of the target product and the selectivity of the reaction is considered. It is shown that the combination of traditional methods of chemical kinetics with modern computational technologies offers opportunities for optimizing laboratory and, in the future, industrial processes for obtaining acetylene from natural gas.