Том 53, № 2 (2019)

The thermal properties of the solid products of supercritical fluid extraction of coal from the Chadan deposit in benzene and the composition of bitumens separated in different temperature ranges (to 120, 120–200, 200–285, and 285–400°C) were studied. In contrast to the original coal, the thermal destruction of insoluble solid coal residue from extraction began at a higher temperature, and it was accompanied by a lower yield of volatiles. A comparative analysis of the characteristic parameters of the IR spectra and chromatograms showed changes in the composition of bitumen as a function of the extraction temperature: at low temperatures, oil components were extracted from coal, and the concentrations of tars and asphaltenes increased with temperature.

A quantum-chemical analysis of the solubility of the high-molecular-weight components of heavy oil containing aromatic and paraffin fragments and N, O, and S heteroatoms was carried out. The results of the calculation of the heats of formation ΔН₂₉₈ of model compounds and their complexes by the RMZ method calibrated using test molecules were obtained. It was shown that the dimers of macromolecules containing alkyl groups and heteroatoms are more stable and better solvated in heptane than in benzene. There is a linear relationship between the free energies of solvation of model compounds in benzene and heptane. According to the thermodynamic calculations of an equilibrium reaction composition, the formation of new complex structures between hydrogen donors and acceptors is possible.

Studies on the thermal destruction of a mixture of vacuum residue (tar) and primary coal tar (PCT) with and without Fe₃O₄ and β-FeOOH catalytic additives, which were performed using thermogravimetry and differential scanning calorimetry in an inert atmosphere at a heating rate of 10 K/min, are reported. Based on the results of thermogravimetric analysis and the kinetic parameters of the process, activation energies were calculated, and these activation energies can be used in the development of methods for the technological calculation of reactors and the selection of construction materials for their manufacture.

The effects of the synthesis time, the amount of alkali, and the amount of alkylating reagent on the concentration of bound carboxymethyl groups and the solubility of the resulting products in aqueous alkaline solutions was studied in the carboxymethylation of peat with sodium monochloroacetate in the presence of sodium hydroxide under mechanochemical treatment conditions.

The oxidation and pyrolysis of brown coal containing 5 wt % CuSO₄ as an initiating additive was studied. The experiment was performed by thermogravimetry at a heating rate of 2.5 K/min in an atmosphere of air and nitrogen. The process characteristics in the pyrolysis and oxidation mode were evaluated, and the activation energy of the process was determined by the Coats–Redfern method. It was established that the addition of the initiating agent CuSO₄ led to a significant decrease in the initial temperature of oxidation and pyrolysis processes to shift the reaction toward the low-temperature region. Maximum changes in the reaction initiation temperatures in the oxidation (ΔT_i) and (ΔT_d) pyrolysis modes were 35 and 50°С, respectively. It was established that the introduction of CuSO₄ led to a decrease in the activation energy of oxidation by 7.1 kJ/mol, and ΔE_a was 10 kJ/mol for the pyrolysis process. A decrease in the residence times of a sample within the limits of the sublimation of volatile substances was observed: Δt_i was 12 min for oxidation, and Δt_d was 18 min for pyrolysis. According to mass-spectrometric analysis data, the presence of SO₂ (peaks at 230 and 320°C) was detected in the oxidation and pyrolysis reaction products of modified samples; this was explained by the chemical interaction of copper sulfate with brown coal components.