Vol 53, No 3 (2019)

The main characteristics of grade 1B brown coal from the Khandinskoe deposit were determined. These are low-sulfur coals. The bitumen content varies from 1.5 to 17.5%, and the average wax content of bitumen is 61.8%. The concentration of humic acids is 40–70%. The yields of extracts, waxes, and tars from the test coals were determined using various extractants and their characteristics were given. Coal from the Khandinskoe deposit can be a promising raw material for the production of lignite wax, coal–alkali reagents, and humic acid preparations.

The biological activity of humic preparations in the form of sodium and potassium humates was investigated depending on the structural group parameters of humic acids (HAs): the degree of aromaticity (f_a), a hydrophilic–hydrophobic parameter (f_hh), and a parameter reflecting the ratio between aromatic and aliphatic fragments in the organic matter of HAs (f_ar/al). Native and modified HAs isolated from peat and brown coals of Russia and Mongolia, the composition of which was characterized using proximate and ultimate analysis and ¹³С NMR (CP MAS) spectroscopy, were used as preparations. It was established that modification by destructive alkylation and the subsequent bitumen removal changed the structural-group composition of HAs, increased the degree of aromaticity, and led to an increase in their biological activity.

A method was proposed for optimizing the process of oil shale pyrolysis with the addition of a cleaning unit. With the use of this method, the degree of removal of H₂S and CO₂ from pyrolysis gas was almost 100%, which makes it possible to use the resulting gas as fuel.

The influence of the composition of the mixtures of petroleum (fuel oil) and vegetable raw materials on the yield and composition of products formed upon the pyrolysis of the mixtures was investigated. Data on the pyrolytic transformations of the mixtures in a temperature range of 140–700°C are given. It was established experimentally that the yield of solid pyrolysis products decreases and the yield of gas and tar increases with the fuel oil content of the mixture. The yield of pyrolysis products also depends on the concentration of emulsified water in the mixtures.

It was established experimentally that the trace elements that are present in brown coal samples in low and ultra-low concentrations are concentrated in the finest fraction of the samples whose particle size is smaller than 1 μm (in a submicron fraction), which was separated using special nanotechnological techniques. A comparative analysis of the concentrations of chemical elements in the gross samples of coal and in the submicron fractions showed the special features of the distribution of trace elements in a coal matrix and prospects for the extraction of potentially valuable elements from coals.

Quantum chemistry methods were used to calculate the energy parameters of an elementary unit and a cellulose macromolecule dimer (cellobiose), and structure simulation was performed and the energy of interaction between the fragments of native cellulose macromolecules was calculated. It was established that the trans conformation of cellobiose is more stable than the cis conformation by 6.7 kcal/mol. Differences in the calculated and real (according to literature data) IR spectra of cellulose were related to the presence of intramolecular and intermolecular hydrogen bonds in the native structure. It was shown that the interaction of individual fragments of cellulose macromolecules from eight monomer units is due to the manifestation of intramolecular hydrogen bonds. It was found that the energies of intermolecular interactions ∆Е essentially depend on the terminal groups X in the cellulose macromolecule fragments, and they are –26, 49, and ‒32 kcal/mol for X = –H, –COOH, and –COH, respectively. The structure of the interacting fragments of cellulose macromolecules can be regulated by replacing the hydrogen atoms of hydroxyl or terminal groups of the macromolecules with functional groups that do not form intramolecular hydrogen bonds and impede self-organization into fibrillar structures. It was shown that compounds with a high electron affinity or a negative energy of the lower vacant molecular orbital are the best reagents for complexation reactions with cellulose.