Objectives. Applying the hydroperoxide method for the co-production of methyl ethyl ketone and phenol, the work studies the kinetic and other characteristics of the individual stages of the developed process to select the optimal conditions for producing the maximum yield of intermediate and target products.

Methods. The research relied on the main theoretical and methodological provisions for the synthesis of intermediate and target products of the cumene technology for the co-production of phenol and acetone. The obtained intermediate and target products were qualitatively and quantitatively analyzed according to modern physicochemical approaches. Gas–liquid chromatography was performed with a Chromatec-Crystal 5000.2 hardware and software complex. The infrared (IR) spectra of the synthesized compounds were recorded with a Spectrum RX-1 IR Fourier spectrometer. ¹H nuclear magnetic resonance (NMR) spectroscopy of substances was conducted using a Bruker DRX 400 NMR spectrometer. A quantitative determination of the content of sec-butylbenzene hydroperoxide was carried out using iodometric titration.

Results. The main stages of the developed method for the co-production of methyl ethyl ketone and phenol based on the hydroperoxide oxidation of sec-butylbenzene were investigated. sec-Butylbenzene was synthesized by alkylation of benzene with 1-butanol in the presence of concentrated sulfuric acid at a yield of about 82%. The hydrocarbon compound was subjected to aerobic liquid-phase oxidation catalyzed by N-hydroxyphthalimide to the corresponding hydroperoxide with a main substance content of 30–35 wt %, feedstock conversion of 34–37%, and selectivity of hydroperoxide formation above 95%. The kinetic and other characteristics were studied for the final stage of the developed method, comprising the acid decomposition of hydroperoxide to methyl ethyl ketone and phenol. Suitable conditions for obtaining target products with high yields were identified.

Conclusions. Methyl ethyl ketone and phenol of high purity with yields of 72 and 74%, respectively, were obtained by the hydroperoxide method. The structures of the synthesized substances were confirmed by IR and ¹H NMR spectroscopy.

Objectives. The work set out to develop catalysts based on nickel and copper obtained by active phase chemical reduction and investigate their activity including the influence of the type of supports on the course of alkylation of amines with primary or secondary alcohols in a plug-flow reactor with a fixed catalyst bed.

Methods. The reactions were carried out in a continuous mode on a fixed bed of an appropriate catalyst in a plug flow microcatalytic apparatus at 160–240°C. NaX zeolite, magnesium oxide, and γ-Al₂O₃ were used as supports. After preparing the catalysts by impregnation from an excess solution of metal salts, the active metal phase was reduced with a sodium tetrahydridoborate aqueous solution. The composition of the resulting products was analyzed by gas–liquid chromatography, while their structure was confirmed by gas chromatography-mass spectrometry. The alkylating agents were ethanol, 2-propanol, 1-butanol, 1-pentanol, benzyl alcohol, and 1-octanol; alkylated amines were 1-butylamine, 1-hexylamine, 1-octylamine, aniline, morpholine, piperidine, and hexamethyleneimine.

Results. The alkylation of amines with alcohols catalyzed by metal (nickel and copper) nanoparticles supported on NaX zeolite, magnesium oxide MgO, and γ-Al₂O₃ in a plug-flow reactor with a fixed catalyst bed at atmospheric hydrogen pressure and 160–240°C leads to the formation of predominantly mono-N-alkylated products with yields up to 99%.

Conclusions. Nickel (or nickel and copper) nanoparticles supported on various supports are effective catalysts for the synthesis of secondary or tertiary amines in the plug-flow reactor.

Objectives. The work set out to investigate the potential for developing an efficient cobalt catalyst for Fischer–Tropsch synthesis through low-temperature activation by reduction in hydrogen directly in the synthesis reactor. Such an approach could be used to enhance the overall economic viability of the process.

Methods. The reduction of a zeolite-containing catalyst with a heat-conducting system based on thermally expanded graphite in an aluminum oxide binder carrier was investigated within the temperature range of 300–400°C. The degree of reduction of the powdered catalyst (to remove diffusion restrictions) was determined by conducting temperature-programmed reduction subsequent to the reduction at the studied temperature. Autosorb-1C and STA 449 F1 (Netzsch, Germany) devices were used in this work. The identified activation mode was evaluated at a Fischer–Tropsch synthesis pilot plant at INFRA (Moscow, Russia).

Results. Activity and selectivity values of the catalyst reduced at 325°C are determined from chromatographic analysis of the products. Low-temperature (325°C) reduction is shown to provide better catalytic parameters due to the implementation of a larger number of highly dispersed cobalt-oxide structures fixed on the hydrated surface of the support, resulting in the appearance of Co^δ+ centers with increased activity and selectivity for the formation of C₅₊ hydrocarbons.

Conclusions. The described catalytic system demonstrates the potential advantages in carrying out reductive activation in hydrogen at 325°C as opposed to the conventional 400°C. This approach markedly enhances the economic viability of the entire process, particularly for small-scale installations, due to the reduced thermal stability of the steel material reactor.

Objectives. Elastomeric materials based on styrene–butadiene–styrene (SBS) triblock copolymers occupy approximately three-quarters of the global thermoplastic elastomer market; in the Russian elastomer market, their share exceeds 80%. Their primary applications include the production of shoe sole materials, anticorrosion coatings, waterproofing, and roofing mastics. The predominant form of degradation of such rubber products, which occurs in the presence of heat and oxygen, is known as thermal-oxidative aging. However, the creation of new functional materials based on modified styrene–butadiene block copolymers will enable the development of materials with enhanced resistance to thermal-oxidative degradation. Chlorinated paraffins, comprising a constituent mixture of polychlorinated n-alkanes, can be applied as halogen-containing modifiers for thermoplastic elastomers to enhance their strength and thermal properties. The aim of the present study is to create climate-resistant elastomeric composite materials based on modified SBS triblock copolymers and investigate the influence of a low molecular weight polychlorinated n-alkane modifier (chlorinated paraffin) on their thermaloxidative stability.

Methods. Composite materials based on the SBS triblock copolymers with various amounts of chlorinated paraffin were prepared using the solution blending method. Fourier-transform infrared spectroscopy (FTIR) was used to analyze the impact of the amount of added modifier on the kinetics of thermal-oxidative degradation. The molecular mobility of the elastomers following thermal-oxidation was studied using the paramagnetic probe method to determine the correlation time that characterizes the rotational mobility of the probe in the elastomer matrix. The strength characteristics of the modified elastomer were investigated using a universal testing machine. The kinetics of the thermal-oxidative process were studied using the manometric solid-phase oxidation method.

Results. The results show that oxidation of SBS thermoplastic elastomers occurs mainly in the butadiene blocks. The degradation of unmodified elastomers is caused by chemical bond breakage reactions in the macromolecules. However, due to the sensitivity of double bonds in the polybutadiene segment of SBS, this thermoplastic elastomer is susceptible to light, ozone, and heat.

Conclusions. The multifunctional effect of the halogen-containing modifier on the elastomer leads to increased thermal-oxidative stability of the SBS triblock copolymer thermoplastic elastomer.

Objectives. The work set out to synthesize Schiff base ligands containing a hydrazone moiety of (Z)-2-((E)-1-hydroxyethylidene)hydrazineylidene)-2-phenylacetic acid, as well as their praseodymium, samarium, europium, and gadolinium complexes, and to study their structure.

Methods. The structure of ligands was identified by infrared (IR), ultraviolet (UV), and nuclear magnetic resonance (NMR) spectroscopy. The structure of the complexes was confirmed by elemental analysis, IR and UV spectroscopy, and thermogravimetric analysis.

Results. The Schiff base ligands containing a hydrazone moiety of (Z)-2-((E)-1-hydroxyethylidene)hydrazineylidene)-2-phenylacetic acid, as well as their praseodymium, samarium, europium, and gadolinium complexes, were synthesized using the authors’ procedure.

Conclusions. NMR and IR spectroscopic data confirm that the Schiff base ligand is in the keto form. There are three absorption bands in the wavelength range of 205–306 nm in the UV spectrum of the ligand. A bathochromic shift is observed in the spectrum of all complexes. The molar ratio of ligand and metal in the complexes was 3 : 1.

Objectives. Thallium halides, in particular KRS-5 (TlBr–TlI), represent one of the most promising classes of optical crystals for applications in the mid- and far-infrared ranges. Nevertheless, the high-quality standards applied to materials used for such applications present considerable challenges in the manufacture of single thallium halide crystals. In particular, when failing to adhere to exacting growth conditions, the samples exhibit polycrystalline characteristics, rendering them unsuitable for utilization. Given the high cost of experiments carried out to ascertain the optimal conditions for growth, computer modeling may present a viable alternative. When taking such an approach to satisfy the specific requirements, it becomes possible to analyze key effects as standalone entities, thus avoiding unnecessary complications resulting from the introduction of a high number of simultaneous unknown variables. Thus, the aim of the present work is to simulate the growth conditions of KRS-5 crystal to ascertain the causes of polycrystallinity in the samples and identify the optimal parameters for obtaining single crystals.

Methods. In order to solve the problem, the finite element method was used. This method is employed for the calculation of temperature distribution, mechanical stresses, convective effects, the rate of spreading of the crystallization front, deformations due to thermal expansion, and other phenomena that arise during the process of crystal formation. The MATLAB package, which includes a module for solving partial differential equations, was used to simulate the crystal growth ampoule. The problem of temperature gradient was solved in axisymmetric approximation.

Results. A computer simulation was employed to calculate the temperature distribution within the material during the growth process. This was used to determine the position and shape of the crystallization front. It is established that polycrystalline samples develop as a consequence of the crystallization front assuming a flat configuration. The optimum temperature in the furnace was determined. The work demonstrated the successful growth of a KRS-5 crystal under the calculated conditions.

Conclusions. The calculations used to identify the underlying cause of polycrystallinity in the samples enabled a determination of the optimal parameters for single crystal growth. On the basis of the calculations, a growth experiment was conducted on the KRS-5 sample. The obtained sample met the requisite criteria for commercial utilization.

Objectives. To study the structure and properties of lithium ferrites obtained by preliminary solid-phase synthesis of samples based on Fe₂O₃-Li₂CO₃-Sm₂O₃ powder mixtures having various concentrations of samarium oxide (0, 4.7, and 14.7 wt %) at 900°C and their subsequent high-temperature sintering at 1150°C.

Methods. The structural and morphological characteristics of the synthesized and sintered samples were studied by X-ray powder diffraction analysis, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry.

Results. The preliminary synthesis gives a two-phase composite structure containing unsubstituted lithium ferrite Li_0.5Fe_2.5O₄ having a spinel structure and a perovskite-like SmFeO₃ phase. An increase in the Sm₂O₃ content from 4.7 to 14.7 wt % in the initial Fe₂O₃-Li₂CO₃-Sm₂O₃ mixture leads to an increase in the amount of the secondary SmFeO₃ phase in the synthesized samples from 4.9 to 18.2 wt %. The high Curie temperature values (631–632°C) and obtained values of the enthalpy of the a→b phase transitions in lithium ferrite indicate that the main product in all synthesized samples is the ordered a-Li_0.5Fe_2.5O₄ phase. Subsequent sintering at elevated temperatures leads to a decrease in the SmFeO₃ phase content to 3.8 and 16.5 wt % and to an increase in the content of the lithium ferrite phase. The sample not modified with samarium contains a significant amount of the disordered b-Li_0.5Fe_2.5O₄ phase, as confirmed by the reduced values of the Curie temperature and phase transition enthalpy. The density of such a sample is 4.4 g/cm³. The introduction of samarium ions leads to the preservation of the ordered a-Li_0.5Fe_2.5O₄ phase during sintering. The density of the sintered samples decreases to 4.3 and 4.1 g/cm³ with an increase in the concentration of samarium oxide introduced at the synthesis stage to 4.7 and 14.7 wt %, respectively.

Conclusions. The introduction of samarium oxide to low concentrations (up to 4.7 wt %) during ferrite synthesis leads to the formation of a two-phase composite structure during sintering, which mainly consists of an unsubstituted lithium ferrite phase having more regular polyhedral grains and a low content of the secondary perovskite-like phase. The formation of the secondary phase, whose properties differ from those of ferrite, along with the characteristics obtained for such samples, which include a slight decrease in density while maintaining a high Curie temperature corresponding to the main magnetic phase, make ferrites modified with low concentrations of rare earth elements promising for further study of their electromagnetic properties in the microwave range.

Objectives. To develop and subsequently verify the calculation block of the mass transfer process in the pervaporation membrane module based on a HybSi^® ceramic membrane using experimental data as a basis for the verification process.

Methods. The task was implemented using a mathematical simulation within the Aspen HYSYS application package, which is designed for modeling chemical engineering processes. The differential equations of the mathematical model were represented as a system of difference equations, which were then solved numerically with an adaptive area step. The membrane pervaporation module of area S during its modeling is divided into n intervals, based on ensuring within the ith interval the condition that the temperature change ΔТ is less than 1°C. A model was constructed to simulate the performance of the membrane module under isothermal and adiabatic operating conditions.

Results. The mathematical model of the pervaporation process employed in the developed computational membrane pervaporation module considers variations in the concentration and temperature of the feedstock flux along the surface of the HybSi^® membrane. The performance of the software module was evaluated by comparing the calculated results with the available experimental data for the dehydration of ethanol and isopropanol. The results demonstrated a high degree of agreement for three isotherms (60, 70, and 80°C) and two variations of pressure on the permeate side (5 and 20 mm Hg). Modeling of the operation of the membrane module with the area of 1 m² in adiabatic mode showed that the processes of alcohol dehydration on HybSi^® membranes are accompanied by significant thermal effects associated with heat consumption to provide evaporation through the membrane due to large transmembrane fluxes.

Conclusions. The comparative analysis of the results of modeling the HybSi^® membrane module in isothermal and adiabatic modes of operation demonstrated that the calculation of the membrane module without consideration of thermal effects results in significant errors. These include an overestimation of the permeate flow rate by up to 50% and an underestimation of the water concentration in the retentate by up to 1.3–1.8 times. It can be reasonably deduced that the omission of thermal effects in design calculations will result in a considerable underestimation of the requisite membrane module surface area.