Key Engineering Materials Vol. 685

Abstract: The processing of the light fraction formed during the separation of amines for components by rectification is investigated. The light fraction which is an aqueous solution with about 1% of ethylenediamine and 2% of ammonia is treated in an electrolyzer with ion-exchange membranes. It is shown that a concentrated product containing about 118 g/l of ethylenediamine, about 106 g/l of ammonia and purified water can be obtained in this case. The concentrated product can be used at the initial stage of amines production.

Abstract: Influence of silver chloride synthesis conditions on its heat of sublimation after ultra-violet irradiation was explored. It was determined that silver chloride synthesized in excess of silver ions after irradiation was characterized by heat of sublimation about 6813 J/g, which meant that the original value increased in ~ 1.8 times. At the same time silver chloride synthesized in excess of chloride ions was characterized by decrease in value of heat of sublimation by ~ 2 times. Growth of heat of sublimation of silver chloride with excess of silver ions is connected with energy expenditure on sublimation due to decrease in proportion of surface which is not covered with silver. Reduction of heat of sublimation of silver chloride with excess of chloride ions is explained by absence of silver solid surface film and catalytic effect of silver klasters formed during the process of irradiation.

Abstract: The technique of platinum (IV) determination in mineral raw materials with the application of stripping voltammetry has been proposed. The authors determined the registration conditions in the determination of the analytical signal Pt (IV): the composition of background electrolyte, the electrolysis potential. The graphite electrode impregnated with polyethylene was used as a working electrode. The use of stripping voltammetry applied to the assessment of the platinum content in geological objects was demonstrated.

Abstract: The paper presents results of scanning electron microscope (SEM) investigations, differential thermal and elemental analyses, and infrared (IR) spectroscopy of micron powders obtained by thermal decomposition of cupric and nickel oxalates before and after their blending with oil. The oil treatment modifies the powder compositions, heteroorganic compounds extracted from oil are observed on their surface. The analysis shows that materials based on copper and nickel micron powders can be used for the prepurification of crude hydrocarbons from heteroatomic compounds.

Abstract: In spite of selectivity of platinum and rhenium stripping voltammetry analysis techniques, it is very difficult to identify them in the presence of other metals. This manuscript reports on the stripping voltammetric determination of platinum and rhenium in the presence of other metals. The effect of accompanying elements on the electrochemical oxidation processes of platinum and rhenium has been described. It has been shown that it is possible voltammetric determination of platinum and rhenium after removal of interfering matrix components of mineral raw materials at the stage of sample preparation.

Abstract: Copper (II), nickel (II) and vanadyl complexes of 1,2-bis (3,5-dimethylpyrazol-1-yl)-1,2-ethanediol were prepared by the reaction of transition metal salts (chloride, acetate, sulfate) with the ligand in ethanol solution. The composition of the complexes was confirmed by elemental analysis and molar conductivity measurements. The coordination modes of the ligand and counter-ions were established from IR spectra and DFT calculations.

Abstract: The calculation data of equilibrium concentrations for calcium ions in ammonium medium have been reported in the paper. The "P2S2R3KA" program was used. It was shown the equilibrium concentrations for calcium ions decrease from 84.16 to 1.0 mg/dm³ in the model solution. The reactant diffusion rate was determined.

Abstract: In the paper we study a method of increasing the yield of dehydrogenation products of methylbutenes by virtue of intermediate removal of the hydrogen formed during the dehydrogenation and partial compensation of heat losses. In the example of dehydrogenation of methylbutenes into the isoprene, the oxidation of hydrogen on the platinum catalyst [charged inside the layer of ferric potassium catalyst] for the dehydrogenation of olefins is considered.

Abstract: The results of experimental investigations of combustion of the powder mixture of titanium, carbon, and ferrous oxide (III) are shown in this paper. Iron reduction by carbon is an endothermic reaction and proceeds in combustion wave of SHS due to the heat of high-exothermic reaction of TiC formation. It was found that it is impossible to initiate the combustion process with (Fe₂O₃+C) content of 50 wt. % or more of the initial charge composition. With not very high content of (Fe₂O₃+C), only Fe and TiC are found in the reaction products. When approaching its content to 50 wt. %, also С and FeO impurity phases are detected. The SHS product is a cake of separate granules of Fe-TiC with the granule size of 100-500 μm.

Abstract: Using the method of combustion synthesis, a series of porous cermet materials from nickel and oxides (such as NiO, MgO, Al₂O₃, ZrO₂, and rare-earth oxides) was synthesized. They investigated in terms of their application as catalysts of the reaction of oxidative coupling of methane into synthesis gas. It is found out that the composites containing about 50% (NiO + Ni) and a small amount (up to 5%) of Ce, La, Nd, and Pr-oxides at the temperature 830^оС ensure the conversion efficiency of methane within 92 ÷ 95% and the H₂/CO ratio 2.0 ÷ 2.1 in the reaction products. The data obtained suggest that the materials manufactured can be effectively used in the systems of syngas manufacturing (for the Fischer – Tropsch process) and in the production of hydrogen from natural gas.