Electrosynthesis of Н<Subscript>2</Subscript>О<Subscript>2</Subscript> from О<Subscript>2</Subscript> in Gas Diffusion Electrodes Based on Black СН600

Furnace black СН600 was studied as a catalyst for electrosynthesis of Н₂О₂ from О₂ in a gas diffusion electrode in alkaline and acidic solutions. The texture properties of the starting black СН600 and gas diffusion electrodes (GDEs) based on it were determined by the low-temperature nitrogen adsorption (LTNA) method. The rate constants of Н₂О₂ decomposition on black and its mixtures with fluoroplast-4D in acidic and alkaline solutions of electrolyte were calculated. The process selectivity γ (the current fraction spent on the two-electron reduction of oxygen), kinetic parameters of oxygen reduction, and double-layer capacity of the СН600-based GDE were determined. Data on the kinetics of hydrogen peroxide accumulation during electrosynthesis from oxygen in СН600-based GDE in acidic and alkaline solutions were obtained.     

Graphitized carbon materials for electrosynthesis of Н<Subscript>2</Subscript>О<Subscript>2</Subscript> from О<Subscript>2</Subscript> in gas-diffusion electrodes

New graphitized carbon materials: technical carbon N220, С140, and СН85 (Omsktekhuglerod) were studied as catalysts of electrosynthesis of alkaline solutions of hydrogen peroxide from oxygen in gasdiffusion electrodes (GDEs). The kinetic parameters of oxygen reduction in alkaline solution and the capacity of gas-diffusion electrodes based on technical carbon N220, С140, and СН85 were determined. Data on the kinetics of hydrogen peroxide accumulation were obtained at different current densities. The fraction of current γ spent on the reduction of oxygen to hydrogen peroxide was determined. The rate constants of hydrogen peroxide decomposition under the given conditions were calculated.     

Comparative Study of the Efficiency of New Technical Carbons СН210 and С40 in Electrosynthesis of Н2О2 from О2 in Gas-Diffusion Electrodes on Their Basis

Russian Journal of Electrochemistry - The efficiency of new brands of technical carbon CH210 and C40 in the electrogeneration of Н2О2 from О2 in gas-diffusion electrodes (GDE) on...     

One-Pot Synthesis of N-Substituted Alkylaminocyclohexanols by the Addition of Electrophiles Formed <Emphasis Type=Italic>in situ</Emphasis> in the System Н<Subscript>2</Subscript>О<Subscript>2</Subscript> + HBr (HCl)

Highly selective one-pot synthesis of N-substituted aminocyclohexanols has been performed by hydroxyhalogenation of the corresponding cyclohexenes with electrophilic reagents formed in situ in the system Н₂О₂ + HHlg (Hlg = Cl, Br), with subsequent substitution of halogen atoms with amines. Some products were tested as antimicrobial additives to motor oils and cooling lubricants and showed high antibacterial and antifungal activity.     

Effect of Fe-zeolite on formation of N<Subscript>2</Subscript>O in selective reduction of NO by NH<Subscript>3</Subscript> over V<Subscript>2</Subscript>O<Subscript>5</Subscript>–WO<Subscript>3</Subscript>/TiO<Subscript>2</Subscript> catalyst

An approach for significantly suppressing N₂O formation in reduction of NO by NH₃ over V₂O₅–WO₃/TiO₂ (VWT) catalyst has been studied by coating different amounts of a Fe-exchanged zeolite (FeZ) onto the catalyst. FeZ-promoted VWT samples were characterized using N₂ sorption, X-ray diffraction (XRD) analysis, and NH₃ adsorption/desorption techniques to understand the primary role of FeZ in lowering N₂O production levels. At high temperatures (≥450 °C), VWT gave N₂O production with high concentrations, while N₂O formation was noticeably reduced when using FeZ-promoted catalysts, which also showed somewhat lower NO removal activities (<5 %) at all temperatures. N₂ sorption and XRD measurements revealed no perceptible physical or chemical alterations of each constituent, even in VWT catalysts after FeZ coating following high-temperature calcination. Adsorption of NH₃ on unpromoted and FeZ-promoted catalysts and subsequent desorption yielded very complicated spectra for N₂O that might primarily come from NH₃ oxidation, and the interaction between V–NO species at temperatures >580 °C. NO on neighboring sites seems to be produced via decomposition of N₂O generated at lower temperatures. The FeZ in the promoted VWT catalysts could be responsible for N₂O decomposition and N₂O reduction with unreacted NH₃ at temperatures >400 °C, thereby significantly lowering N₂O emission levels. This promotional effect bodes well for use in many industrial deNO _x applications.     

Effect of ZrO<Subscript>2</Subscript> on Catalyst Structure and Catalytic Sulfur-Resistant Methanation Performance of MoO<Subscript>3</Subscript>/ZrO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts

A series of MoO₃/ZrO₂–Al₂O₃ catalysts was prepared and investigated in the sulfur-resistant methanation aimed at production of synthetic natural gas. Different methods including impregnation, deposition precipitation, and co-precipitation were used for preparing ZrO₂–Al₂O₃ composite supports. These composite supports and their corresponding Mo-based catalysts were investigated in the sulfur-resistant methanation, and characterized by N₂ adsorption–desorption, XRD and H₂-TPR. The results indicated that adding ZrO₂ promoted MoO3dispersion and decreased the interaction between Mo species and support in the MoO₃/ZrO₂–Al₂O₃ catalysts. The co-precipitation method was favorable for obtaining smaller ZrO₂ particle size and improving textural properties of support, such as better MoO₃ dispersion and increased concentration of Mo⁶⁺ species in octahedral coordination to oxygen. It was found that the MoO₃/ZrO₂–Al₂O₃ catalyst with ZrO₂Al₂O₃ composite support prepared by co-precipitation method exhibited the best catalytic activity. The ZrO₂ content in the ZrO₂Al₂O₃ composite support was further optimized. The MoO₃/ZrO₂–Al₂O₃ with 15 wt % ZrO₂ loading exhibited the highest sulfur-resistant CO methanation activity, and excess ZrO₂ reduced the specific surface area and enhanced the interaction between Mo species and support. The N₂ adsorption-desorption results indicated that the presence of ZrO₂ in excessive amounts decreased the specific surface area since some amounts of ZrO₂ form aggregates on the surface of the support. The XRD and H₂-TPR results showed that with the increasing ZrO₂ content, ZrO₂ particle size increased. These led to the formation of coordinated tetrahedrally Mo⁶⁺(T) species and crystalline MoO₃, and this development was unfavorable for improving the sulfur-resistant methanation performance of MoO₃/ZrO₂–Al₂O₃ catalyst.     

Lanthanide-Organic Frameworks Based on {Ln<Subscript>4</Subscript>(μ<Subscript>3</Subscript>-OH)<Subscript>4</Subscript>(μ<Subscript>2</Subscript>-OH)<Subscript>2</Subscript>} Cluster Units

Abstract  

Three novel lanthanide-organic frameworks: [Ln₂(pyba)₃(μ₃-OH)₂(μ₂-OH)(H₂O)] _n (Ln = Er (1), Y (2), Dy (3) Hpyba = 4-pyridin-4-yl-benzoic acid) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Structure analysis shows that each {Ln₄(μ₃-OH)₄(μ₂-OH)₂} cluster units interconnect to form 1-D chains, which are further linked by π–π interactions to make a 3-D supramolecular network structure. Furthermore, the IR, PXRD and TGA of compounds 1–3 were also studied.     

Formation of solid solutions of multiferroics in the Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> system

The sequence of phases appearance during the formation of Bi_1–xNd_xFeO₃ solid solutions in powder oxides mixtures of bismuth, neodymium, and iron has been determined. It has been shown that the closeness of the reaction mixture composition to that of the individual compound (BiFeO₃ or NdFeO₃) is essential for the realization of the series of phase transformations yielding solid solutions of multiferroics Bi_1–xNd_xFeO₃ as the final product, due to the prevalence of various interphase contacts in the starting reaction zone.     

Thermal analysis study of LiFeO<Subscript>2</Subscript> formation from Li<Subscript>2</Subscript>CO<Subscript>3</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> mechanically activated reagents

Series of n-octadecane/expanded graphite composite phase-change materials (PCMs) with different mass ratio were prepared using n-octadecane as PCMs, expanded graphite as multi-porous supporting matrix through vacuum impregnation method. Microstructure, crystallization properties, energy storage behavior, thermal cycling property and intelligent temperature-control performance of the composite PCMs were investigated. Results show that the composite PCMs have a good energy storage property. The melting enthalpy and crystallization enthalpy can reach 164.85 and 176.51 J g^?1, respectively. Furthermore, the good thermal conductivity of expanded graphite reduces the super-cooling degree of n-octadecane and endows the composite PCMs with fast thermal response rate and excellent thermal cycling stability. As a result, the phase-change temperatures and phase-change enthalpy almost have no change after 50 thermal-cooling cycles. The test of intelligent temperature-control performance shows that the electronic radiator filled with the composite PCMs possesses a high intelligent temperature-control performance, and its temperature can sustain in the range of 22–27.5 °C for about 6120 s. These results indicate that the prepared composite PCMs possess good comprehensive property and can be widely used in energy storage and thermal management systems.     

The oxidative-dissolution behaviors of fission products in a Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O<Subscript>2</Subscript> solution

This study was carried out to investigate the characteristics of an oxidative-dissolution of fission products (FP) when uranium (U) is dissolved in a Na₂CO₃–H₂O₂ carbonate solution. Simulated FP-oxides which contained 12 components were added to the solution to examine their dissolution behaviors. It was found that H₂O₂ was an effective oxidant to minimize the dissolution of FP. For the 0.5 M Na₂CO₃–0.5 M H₂O₂ solution, such elements as Re, Te, Cs, and MoO₂ were dissolved with yields of 98 ± 2%, 98 ± 2%, 93 ± 2%, and 26 ± 3%, respectively, for 2 h. Among these components, Re, Te, and Cs were completely dissolved within 10–20 min without regard to the concentrations of Na₂CO₃, and H₂O₂ due to their high solubility in the carbonate solution with and without H₂O₂. However, MoO₂ was very slowly dissolved and its yield was 29 ± 3% for 4 h. The pH of the dissolved solution revealed the greatest influence on the dissolution yields of the FP, exhibiting the most effective pH condition in the range of 10–12 in order to create a considerable suppression of the co-dissolution of FP during the oxidative-dissolution of U.     

Effects of Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> on the crystallization and structure of CaO–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> glass ceramics

Radiation-induced degradation of the weakly and strongly 4-vinylpyridine basic ion exchange resins by gamma radiolysis was investigated in the presence of air and liquid water. This study is focused on evaluating the radiolytic gases (H₂, CO, CO₂ and CH₄) and liquid products (water-solute TOC and NH₄ ⁺). The weakly basic resin yielded lower amounts of H₂ and CO and higher amounts of CO₂ than those of the strongly basic resin. Moreover, the strong basic resin tended to yield greater amounts of NH₄ ⁺. Resins were characterized by the FTIR spectroscopy technique and the results showed that the resins structures are relatively stable.     

Oxidative leaching of uranium from SIMFUEL using Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O<Subscript>2</Subscript> solution

A feasibility and basic study to find a possibility to develop such a process for recovering U alone from spent fuel by using the methods of an oxidative leaching and a precipitation of U in high alkaline carbonate media was newly suggested with the characteristics of a highly enhanced proliferation-resistance and more environmental friendliness. This study has focused on the examination of an oxidative leaching of uranium from SIMFUEL powders contained 16 elements (U, Ce, Gd, La, Nd, Pr, Sm, Eu, Y, Mo, Pd, Ru, Zr, Ba, Sr, and Te) using a Na₂CO₃ solution with hydrogen peroxide. U₃O₈ was dissolved more rapidly than UO₂ in a carbonate solution. However, in the presence of H₂O₂, we can find out that the leaching rates of the reduced SIMFUEL powder are faster than the oxidized SIMFUEL powder. In carbonate solutions with hydrogen peroxide, uranium oxides were dissolved in the form of uranyl peroxo-carbonato complexes. UO₂(O₂) _x (CO₃) _y ^2−2x−2y , where x/y has 1/2, 2/1.     

Kinetics and mechanism of the low-temperature oxidation of carbon monoxide with oxygen on a PdCl<Subscript>2</Subscript>–CuCl<Subscript>2</Subscript>/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst

A systematic study of the kinetics of the low-temperature oxidation of carbon monoxide with oxygen on a PdCl₂–CuCl₂/γ-Al₂O₃ supported catalyst was carried out over a wide range of the partial pressures of oxygen, water, and CO in order to test hypotheses on the reaction mechanism. It was shown that, as the temperature was increased from 20 to 38°C, rate of formation of CO₂ decreased and the apparent activation energy was about–40 kJ/mol. The hypotheses of different degrees of complexity concerning the reaction mechanism were formulated based on physicochemical data and a Langmuir–Hinshelwood model. Mechanisms in which carbon dioxide is formed on the interaction of the surface Pd(I) and Pd(II) complexes that include carbon monoxide and water with the surface complex of Cu(I) that coordinates oxygen were recognized as the most probable.     

Synthesis and structure of the complex [Mo<Subscript>3</Subscript>(μ<Subscript>3</Subscript>-S)(μ<Subscript>2</Subscript>-S<Subscript>2</Subscript>)<Subscript>3</Subscript>(Et<Subscript>2</Subscript>NCS<Subscript>2</Subscript>)<Subscript>3</Subscript>]I

The structure of tri-μ₂-disulfido-μ₃-thiotris(diethyldithiocarbamato)-S,S′-triangle-trimolybdenum iodide [Mo₃(μ₃-S)(μ₂-S₂)₃(Et₂NCS₂)₃]I was determined. The compound was characterized by differential thermal analysis and IR, Raman, and X-ray electronic spectroscopy.     

Glass Formation in the Ternary System La<Subscript>2</Subscript>O<Subscript>3</Subscript>–As<Subscript>2</Subscript>S<Subscript>3</Subscript>–Er<Subscript>2</Subscript>O<Subscript>3</Subscript>

The boundaries of the glass formation region in the ternary system La₂O₃–As₂S₃–Er₂O₃ were found. Transparent glass of composition (La₂O₃)_0.03(As₂S₃)0.90(Er₂O₃)0.07 was studied by X-ray photoelectron and Raman spectroscopy. The intensities of the bands characterizing As–S, La–O, and Er–O bonds increased, and these bands were shifted toward higher energies. This was due to an increase in the covalence of these bonds and probably due to the formation of new bonds in the glasses. Samples in the glass formation region are resistant at 300 K to air, water, and organic solvents.     

Oxidation of Adamantane with H<Subscript>2</Subscript>O<Subscript>2</Subscript>–CF<Subscript>3</Subscript>COCF<Subscript>3</Subscript> · 1.5 H<Subscript>2</Subscript>O in the Presence of VO(acac)<Subscript>2</Subscript>

The system hydrogen peroxide–hexafluoroacetone sesquihydrate effectively oxidizes adamantane in the presence of VO(acac)₂ to afford 64% of adamantan-1-ol in tert-butyl alcohol or 76% of adamantan-2-one in a mixture of acetic acid with pyridine.     

Rearrangements and Tautomeric Transformations of Heterocyclic Compounds in Homogeneous Reaction Systems Furfural–Н<Subscript>2</Subscript>О<Subscript>2</Subscript>–Solvent

General information on the reactions of furfurals with hydrogen peroxide is given. We have discussed the Baeyer–Villiger rearrangement of furan 2-hydroxyhydroperoxides and tautomeric transformations with proton transfer of 2-hydroxyfuran and β-formylacrylic acid formed in a homogeneous reaction system furfural–Н₂О₂–solvent under the catalysis with the formed acids. The factors affecting these rearrangements and tautomeric transformations as well as their specificity in comparison with benzene type compounds, and the pathway of the reactions of furan aldehydes with Н₂О₂ in water have been analyzed. Ketoenol tautomerism of cyclic hemiacetal form of β-formylacrylic acid leading to its transformation into succinic anhydride has been described for the first time.     

Reciprocal system 3Tl<Subscript>2</Subscript>S + Sb<Subscript>2</Subscript>Se<Subscript>3</Subscript> ⇆ 3Tl<Subscript>2</Subscript>Se + Sb<Subscript>2</Subscript>S<Subscript>3</Subscript>

Phase equilibria in the reciprocal system 3Tl₂S + Sb₂Se₃ ? 3Tl₂Se + Sb₂S₃ are investigated by DTA, X-ray powder diffraction, and emf measurements. Some polythermal sections, the isothermal section of the phase diagram at 400K, and the liquidus-surface projection for this system are constructed. The types and coordinates of invariant and univariant equilibria are determined. It is shown that the system is non-diagonal. Broad regions of solid solutions are found on the basis of the binary compounds Tl₂S and Tl₂Se and along the boundary system Sb₂S₃-Sb₂Se₃ and the sections Tl₃SbS₃-Tl₃SbSe₃, TlSbS₂-TlSbSe₂, and TlSb₃S₅-TlSb₃Se₅ of the phase diagram.