Russian Journal of Applied Chemistry最新文献

Published data on hydrodesulfurization and hydrodenitrogenation of model petroleum compounds in the presence of molybdenum and tungsten phosphides are analyzed. The majority of papers in which these catalysts are compared to traditional sulfide catalysts demonstrate higher activity of the phosphide catalysts. The influence exerted on the activity of phosphide catalysts in these processes by the feed composition (presence of sulfur- and nitrogen-containing compounds), catalyst synthesis conditions and active phase content, reaction conditions, and promoter is described. When performing the synthesis at high temperatures or using large amounts of the active phase deposited onto an Al-containing support, the catalyst activity can decrease owing to the formation of AlPO₄. The promotion of molybdenum and tungsten phosphides with nickel or cobalt enhances the catalyst activity. The major cause of phosphide deactivation is the presence of nitrogen-containing compounds in the feed, whereas the presence of sulfur-containing compounds, on the contrary, in most cases leads to an increase in the catalyst activity owing to the formation of the phosphosulfide phase.

The corrosion of 10Cr18Ni10Ti and 10Cr17Ni13Mo2Ti austenitic constructional steels in 5% hydrochloric acid containing an inhibitor based on aqueous extracts of aspen (ABE), spruce (SBE), and pine (PBE) bark was studied by gravimetric and electrochemical methods. Such solutions are used for washing and chemical cleaning of cooking and heat-exchange equipment. The influence of temperature and composition of inhibitors on the process was examined. New data on the kinetics of the acid corrosion of the steels were obtained and analyzed. At equal concentration of 1 g L^–1, the inhibiting effect of water-extractable substances (WESs) of wood bark on the acid corrosion of steels increases in the order PBE < SBE < ABE. The inhibiting effect also increases with an increase in the WES concentration to 3.8 g L^–1 and in the temperature from 20 to 50°С, on mixing extracts of different kinds of bark, and to a still greater extent on introducing a synergistic agent, hexamethylenetetramine or potassium iodide, into the extracts.

The structure and physicochemical properties of glycoluril were studied to evaluate the possibility of using it as a filler additive to polymer composite materials to stimulate their biodegradation. The mean particle size of glycoluril was determined (5–10 μm). Glycoluril was found to be stable at temperatures below 270°C. Its particles efficiently reflect visible light. Glycoluril particles and their aggregates have high specific surface area. High parameters of glycoluril bioassimilation with a mold fungus culture determine the potential of this compound for use in biodegradable polymer compound formulations.

A V₂O₅-based composite positive electrode for a lithium-ion battery was optimized through the selection of a polymer binder. The electrochemical characteristics of a V₂O₅-based composite material for the positive electrode with the addition of a polymer binder: polyvinylidene fluoride, polyacrylic acid, polyacrylonitrile, carboxymethylcellulose, and sodium alginate, were determined. Electrodes made from V₂O₅-based composite materials with the addition of polyacrylic acid as a binder are characterized by consistently high capacity (290 mAh g^–1) charged at a normalized current of 0.1 C [current C (mA) is sufficient to fully charge the electrode of a weight m (g) for a time t = 1 h], and at anode/cathode cycling they retain capacity of about 98% after 60 charge/discharge cycles.

Commercial processes for conversion of carbon-containing gases to syngas and hydrogen are considered. The techno-economic characteristics of the main hydrocarbon gas conversion processes (steam methane reforming, partial oxidation, autothermal reforming) used by world’s leading chemical and petrochemical companies and implemented on the commercial or semicommercial scale are presented. The characteristics of these processes are analyzed. The processes of steam conversion, autothermal reforming, and partial oxidation of methane have specific predominant application fields depending on the feed composition and requirements to the composition of the syngas obtained. The steam conversion can ensure the maximal H₂/CO molar ratio in the syngas obtained, and the processes of autothermal reforming and partial oxidation of methane do not require external heat supply to the reactor and are simple in implementation. Analysis of the syngas market shows that the main drivers of its progress can be the need for alternative resources and the stable demand of the chemical industry.

The kinetics of low-temperature (10–50°C) oxidation of CO in the presence of a homogeneous catalytic system consisting of Pt halide complexes and phosphomolybdic heteropolyacid doped with vanadium(V) atoms was studied. A heteropolyacid solution, used as an example, with a low content of catalytically active vanadium atoms (Н₇РМо₈V₄O₄₀), the optimal process conditions (CO concentration, content of Pt and halide ions, pH) were determined, a kinetic equation was derived, and a mechanism was proposed. It was shown that the introduction of catalytic amounts of palladium salt makes it possible to eliminate the induction period of the CO oxidation reaction, as well as to increase the stability of the catalytic system. Significant activity and stability of the combined system Pt + Pd + Н₁₀Р₃Мо₁₈V₇O₈₄ was demonstrated.

Copolymers of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride with acrylic, methacrylic, crotonic and vinylacetic acids were synthesized by radical copolymerization in the presence of a radical initiator azobiisobutyronitrile. Composite materials containing silver nanoparticles ranging in size from 7 to 43.5 nm, depending on the nature of the polymer matrix, were fabricated according to the borohydride method. The structure of the nanocomposites was analyzed by UV, IR, NMR spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. The synthesized nanocomposites have antimicrobial activity and are promising for the creation of new drugs.

Ag(0)–ZnFeOH 0D–2D nanocomposite can be prepared by successive ionic layer deposition (SILD) on the titanium surface. The nanocomposite consists of 10–20 nm silver nanoparticles located on the surface of ZnFeOH 2D nanocrystals of the ultrathin nanosheet morphology. The morphology, composition, and crystal structure of the compound synthesized were studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. As shown by the method of diffusion into agar, the nanocomposite, compared to the initial nanocomponents, exhibits increased antibacterial activity and prolonged action toward Staphylococcus aureus and Escherichia coli bacterial strains.

The electrochemical properties of an electrode material based on a high-capacity silicon/reduced graphene oxide composite are studied. It was determined that the optimal potentials for reversible insertion/extraction of lithium are in the range of 50–2000 mV. The discharge capacity is 980 mAh g^–1 at the charge rate 0.3 C and discharge rate 1.0 C. The addition of vinylene carbonate to the electrolyte solution leads to the stabilization of the solid electrolyte layer on the electrode surface. The discharge capacity is 866 mAh g^–1 at the 170th charge/discharge cycle.