A. M. Gyul’maliev

Thermodynamic and quantum chemical study of the transformations and operation mechanism of molybdenum catalysts under hydrogenation conditions

Structural transformations and the mechanism of the operation of molybdenum-containing catalysts under hydrogenation conditions have been studied by chemical thermodynamics and quantum chemistry methods, as well as the role of sulfur compounds in this process. It has been shown that molybdenum disulfide, an effective hydrogenation catalyst, is produced via the reaction of molybdenum oxide with hydrogen sulfide, not elemental sulfur. It has been concluded that the introduction of elemental sulfur (which is subsequently converted into hydrogen sulfide) or an organic sulfur compound into the reaction system, on one hand, facilitates the transformation of molybdenum oxides into MoS2 and, on the other hand, yields the effective reagent H2S, which takes part in the disproportionation reactions involving hydrogen transfer.

Hydroconversion of polyethylene and tire rubber in a mixture with heavy oil residues

The results of studies on the processing of solid polymer wastes in a mixture with the heavy petroleum residues by hydroconversion with the use of the precursors of nanosized catalysts are given. It was found that the results of their TGA, kinetic parameters (weight losses, the temperature of a maximum rate of decomposition, and the rate constant of decomposition), and data on hydroconversion under the same conditions (the yields of gas, liquid products, and solid residue) are essentially different because of differences in the structural characteristics of polyethylene, tire rubber, and tar. The positive influence of linear polymers on their joint processing with tar was noted.

The formation of nanosized molybdenum oxide particles in a hydrocarbon medium

This work is concerned with the preparation of nanosized particles of molybdenum oxides from an “inverted” emulsion of an aqueous ammonium paramolybdate solution in a pentadecane medium and in the presence of surfactants. The characteristics of disperse-phase particles and the factors, such as the metal concentration, the treatment temperature, and the water and surfactant contents, that affect these characteristics are analyzed.

Calculation of the enthalpy of formation of coal organic matter

The enthalpy of formation for the organic matter of coals in the coal rank series was calculated from the heat of the complete combustion reaction. Three variants were considered in which the experimental heating values Qidaf and the values found from the correlation equation or calculated using the Mendeleev formula were taken as the heat of the complete combustion of coals.

Classification of fossil fuels according to structural-chemical characteristics

On the basis of a set of linear equations that relate the amount of major elements nE (E = C, H, O, N, S) in the organic matter of fossil fuels to structural characteristics, such as the number of cycles R, the number of atoms nE, the number of mutual chemical bonds, the degree of unsaturation of the structure δ, and the extent of its reduction B, a structural-chemical classification of fossil coals that is closely related to the parameters of the industrial-genetic classification (GOST 25543-88) is proposed. Structural-chemical classification diagrams are constructed for power-generating coals of Russia; coking coals; and coals designed for nonfuel purposes including the manufacture of adsorbents, synthetic liquid fuel, ion exchangers, thermal graphite, and carbon-graphite materials.

Thermodynamic and quantum-chemical study of the oxidative dehydrogenation of ethane to ethylene

The equilibrium product composition for the reaction of ethane dehydrogenation to ethylene with various quantities of oxygen fed to the reaction medium has been calculated using methods of chemical thermodynamics. Quantum-chemical calculation of the energy of interaction of ethane with molybdenum dioxide, used as an example, has shown that the absolute energy minimum in the energy profile of the potential energy surface along the ethane dehydrogenation reaction coordinate corresponds to the complex MoO2⋯H2⋯C2H4.

Thermodynamic evaluation of the compounds of gold, silver, and other trace elements formed upon the combustion of brown coal

The thermodynamically most probable main compounds of Ag, Au, Ge, Se, Sr, U, and ash-forming elements formed upon the combustion of brown coal, which was close in the composition of organic and mineral matter to coal from the Nazarovskoe deposit of the Kansk-Achinsk Basin, were determined. According to the experimental data, silver (in the form of AgO(g)) and gold (in the form of Au(g)) quantitatively passed into a gas phase at temperatures higher than 200 and 1179°C, respectively; selenium passed into a gas phase in the form of SeO2(g) at t = 800–1000°C and in the form of SeO2(g) and SeO(g) at t ≥ 1000°C. The SeO(g): SeO2(g) ratio increased with temperature. Germanium formed gaseous GeO(g) and GeO2 at t ≥ 1000°C, and the amount of the former dramatically increased with temperature.

Average structural model of humic acids of peat origin

Based on the data of the elemental, IR-spectroscopic, quantitative functional, and cryoscopic analyses of humic acids isolated from the peats of Tver oblast, an average structural model of these acids is proposed; it reflects the main special features of the chemical structure of the test substances.

Use of the structure parameter for predicting the properties of high-molecular-mass organic compounds

The structure parameter “degree of unsaturation,” which is defined for a structural unit composed of hundred carbon atoms, is proposed for the assessment of characteristics of high-molecular-mass organic compounds. The introduction of the structure parameter has been substantiated. For the natural bitumen and fractions of its hydrogenation products used as an example, it has been shown that the density is linearly related to the number of bonds and the average molecular mass correlates with the parameter of unsaturation in the structural unit. The proposed structure parameter can be used for tentative classification of high-molecular-mass hydrocarbons and their processing products.

Catalytic hydrogenation of Oi-Karagai coal

The hydrogenation of Oi-Karagai lignite (Kazakhstan) is investigated, with a view to its use in the production of motor fuel and other valuable chemical products. The hydrogenation catalysts considered are Turgai bauxite, bentonite, red mud, and wastes from titanomagnesium production. The best results are obtained with bauxite containing 24.2 wt % Fe2O3; in particular, the yield of liquid products is the greatest. By modification of this catalyst with 1.5 wt % elementary sulfur and increase in the pressure from 2.8 to 5.2 MPa, the total yield of liquid products may be increased from 52.2 to 60.3 wt %. On the basis of the experimental results, by nonlinear regression, the dependence of the yield of liquid products on the content of elementary sulfur and the pressure is determined. The dependence on the sulfur content is extremal; the dependence on the pressure is linear. Preliminary radiation treatment of the coal with the optimal dose—150 kGy—is found to increase the yield of liquid products from 52.2 to 62.2 wt %. The yield of the most valuable fraction (the kerosene-gasoline fraction) increases by 6–10 wt % here. The functional dependence of the yield of liquid products on the radiation dose and the concentration of free radicals is extremal. Preliminary mechanical activation of the coal does not lead to dispersion, but free radicals are formed. The optimal time for preliminary mechanical activation—20 min—permits increase in the yield of liquid products from 52.2 to 60.5 wt %. By nonlinear regression, we obtain the functional dependence of the yield of liquid products on the duration of preliminary mechanical activation and the concentration of free radicals. In both cases, the dependence is extremal.