Coke and Chemistry最新文献

The organic mass of coal from different fields is studied by X-ray diffraction. On the X-ray diffraction patterns, the amorphous carbon structure of the coal mainly corresponds to broad intense peaks due to its disordered stacking, with narrow peaks corresponding to the mineral component. X-ray analysis permits not only diagnostics of any carbon component but also determination of the dynamics and mechanism of phase transformations in carbon systems under the action of physicochemical factors. The mineral component of the coal mainly consists of oxidized silicon. Calcium is present in the coal’s organic mass. Iron and aluminum appear partially as organomineral compounds in mineral inclusions. The goal of the research is to select the optimal coal for the production of specialized activated carbon additives that may be used in the thermal hydrocracking of heavy oil-refining residues. These additives must meet requirements on their mineral composition and chemical structure.

The action of nanosecond laser pulses (wavelength 532 nm, pulse length 14 ns, pulse repetition rate 6 Hz, energy density of laser radiation 0.2–0.6 J/cm²) in G and Zh coal pellets is investigated, in an argon atmosphere. The gaseous products of sample pyrolysis include H₂, CH₄, C₂H₂, CO, and CO₂. The content of the gaseous components is determined as a function of the laser energy density. In the range 0.2–0.4 J/cm², the volume of flammable gases formed (referred to the mass loss of the sample) increases; at higher energy densities, practically no change in volume is observed. The gross calorific value of the flammable gases increases linearly from ~8–10 to 19 MJ/m³ with increase in energy density of the laser radiation from 0.2 to 0.6 J/cm². A nanosecond pulse of energy density more than 0.4 J/cm² results in intense ablation of the pellets containing 0.005 wt % polyvinyl alcohol. The coal pellets that contain no binder break down under the action of a nanosecond laser pulse of energy density exceeding 0.2 J/cm².

A process is developed for the production of highly reactive water–coal fuel by oil granulation, vibrational and cavitational treatment of water–coal suspension, with the addition of a highly reactive component (methanol). The preparation of such water–coal fuel from Kuznetsk Basin coal of different ranks and with different ash content is studied experimentally. The possibility of obtaining a composite fuel using fuel oil and methyl alcohol is investigated. The method is refined and the parameters of deep coal enrichment by means of oil granulation are determined. Coal–oil granulates of ash content ≤5.5% are obtained, and the possibility of preparing highly reactive water–coal fuel on that basis by the proposed technological process is considered. The highly reactive water–coal fuel is prepared by wet crushing of coal in a vibrational mill, with treatment of the suspension obtained in a rotary–pulsational cavitation system. The structural, rheological, and thermophysical properties of the highly reactive water–coal fuel are investigated. The flash point of the fuel when methanol constitutes 51.3% of the liquid phase is 29°C; its freezing point is below –14.5°C.

Coal from the Kansk-Achinsk and South Ural basins and their extracts—humic acids, hymatomelanic acids, and bituminous resins—are studied by technical and elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and ¹³C NMR spectroscopy. The bitumen composition is investigated by chromatography and mass spectrometry. Data are presented for the phytostimulant activity of hymatomelanic acids and their mixtures with the saponifiable component of the extracted bituminous resin with respect to Aphrodite wheat seeds. Such activity is established for the samples, whether used individually or in combination. The phytoactivity index (PI) is found to be in the range 1.09–1.20.

The thermal stability of carbon sorbents modified by ammonium bromide is investigated. The sorbent is produced from D coal by alkaline activation at 800°C with 1 h holding, when the coal/KOH mass ratio is 1.0. This sorbent is microporous, with a high specific surface (1340 m²/g). The sorbent is modified by steeping with ammonium bromide solution of different concentrations (1, 2, and 4%). Such modification changes all the textural characteristics of the sorbent. The specific surface S_BET and total pore volume V_Σ decrease. Thermogravimetric analysis establishes the temperature limits on oxidative pyrolysis of the sorbent samples: the ignition temperature and complete combustion temperature. Taking account of the time parameters, the ignition and combustion indices are calculated. It is found that increase in concentration of the ammonium bromide solution is accompanied by increase in the ignition temperature T_ig of the samples and also the temperature T₁ at which mass loss begins. In addition, the ignition index D and combustion index S increase. The results show that modification of the sorbents with ammonium bromide raises the threshold of oxidative pyrolysis.

The development of coal flotation using a modifier is considered. The modifier considered is a petrochemical product: sodium μ-iso-nonylphenoxyethylene carbonate (Sinterol). Its molecules contain an anionic–cationic structure with the general formula: H₁₉C₉–C₆H₄–O(C₂H₄O)_nCOONa. In studying the influence of the modifier consumption on the effectiveness and selectivity of coal flotation, the collector employed is an oil-refining byproduct: Motoalkilat (MTA). The frothing agent is KOBS, which is the still residue from the production of butyl alcohol. The acetylene reagent DK-80 is also employed as a collector. By using DK-80 reagent and the modifier Sinterol in the flotation of coal with different mineral content, the physicochemical properties of the coal surface may be altered and the flotation process may be improved. This combination reduces the consumption of the main reagents and tends to increase the extraction of combustible mass in the concentrate and to reduce the losses of organic mass with the flotation wastes. In addition, the use of Sinterol diminishes the environmental impact of flotation.

Abstract—This article forms part of research on the selection of coal for the production of activated carbon to be used in the thermal hydrocracking of heavy tar residues. It is devoted to the use of electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy to determine the structural and molecular composition of Berezovsky and Kaichaksky-1 lignite and also D coal, in selecting the optimal coal for sorbent production. Comparison of the IR and NMR results indicates that the aliphatic side chains in the selected coal samples are shorter than those in other Siberian coal samples. Comparison of NMR and EPR data shows that, compared to Berezovsky lignite, Kaichaksky-1 lignite has a higher content of oxygen-bearing groups. Its paramagnetism is due to the presence of aroxyl radicals of semiquinone and phenoxyl type. EPR spectroscopy indicates that Kaichaksky-1 lignite has the highest content of paramagnetic complexes based on Fe³⁺. That may affect the quality of the sorbents produced.