Solid Fuel Chemistry最新文献

Supported iron catalysts based on a carbon-containing material, biochar obtained by the hydrothermal carbonization of biopolymers (cellulose and lignin), were studied. The catalytic systems showed high activity in the Fischer–Tropsch synthesis. A composition of C₅₊ liquid products, uncharacteristic for iron-containing catalysts, characterized by high isoalkane content (up to 55%) was recorded. This fact was discussed in the context of the theory of bifunctional centers proposed by A.L. Lapidus with coworkers. It was suggested that the active centers of the test catalysts can be considered bifunctional (a carbide phase and an oxide phase). A correlation between the Fischer–Tropsch synthesis data on the test catalysts and the data obtained by Lapidus and coworkers on cobalt-containing catalysts was shown.

The sorption properties of high-moor peat and products of its sequential disassembly were studied and the binding of Cs-137 by the test materials was evaluated. According to the results of low-temperature nitrogen adsorption, the specific surface area of pores in the test materials varied in a range from 1.48 to 5.96 m²/g, and the total pore volume varied from 0.002 to 0.009 cm³/g. The limiting adsorption of Cs-137 on the test high-moor peat ranged from 1 to 51 Bq/g, which significantly exceeded the background values of Cs‑137 activity determined in the peat deposit and indicated a high sorption capacity of high-moor peatlands with respect to anthropogenic radionuclides. For peat derivatives obtained by the sequential disassembly method, the values of limiting sorption ranged from 2 to 61 Bq/g in the test range of pH. It was revealed that the pH of the medium and the nature of a sorbent are the key factors determining the efficiency of Cs-137 sorption. It was established that the values of the limiting sorption of Cs-137 for peat and products based on it increased with pH

The characteristics of thermal decomposition and combustion processes on the heating of fine particles (100–200 μm) of Chernogorsky coal, larch wood, and mixtures based on them, including the concentrations of the main components of flue gases (CO, CO₂, NO_x, and H₂S + SO₂), were determined using modern techniques, analytical instrumentation, and experimental equipment. The biomass contents of the fuel mixtures based on coal were 10, 20, and 30 wt %. The temperatures at which the ignition of the coke residue occurred and the combustion process was completed were established using the thermogravimetric analysis of individual solid fuels and their mixtures. Larch sawdust was more reactive than Chernogorsky coal due to the lowest temperature at which the carbon residue was ignited; therefore, the addition of even 10% biomass to coal had a positive effect on the reactivity of the mixture. Under conditions of fuel heating in a flow of air at temperatures of 500–800°C, the ignition delay times were determined using a hardware–software complex for high-speed video recording of fast processes. Based on the results of the experimental studies, it was found that the ignition delay times of the test fuels in a flow of heated air varied in a range from 0.02 to 0.22 s, and the addition of 10–30 wt % biomass to coal shortened the ignition delay times of fuel mixtures by up to 50%. The analysis of flue gases upon the combustion of solid fuels made it possible to establish the concentrations of the main anthropogenic emissions; the use of biomass as an additive to coal reduced the emissions of carbon dioxide, nitrogen oxides, and sulfur compounds (H₂S + SO₂) by 2.2–13.5, 6.2–28.9, and 18.2–33.3%, respectively.

Composite materials based on amino-containing humic acids with the introduction of carbon nanotubes, capable of molecular recognition and selective binding of a target metal, were obtained using molecular imprinting, and their composition and physicochemical properties were studied.

The possibility of obtaining carbon sorbents from a fine fraction of medium-temperature coke for the removal of phenols from industrial water and wastewater was demonstrated. This excludes the carbonization of coal material as one of the economically costly stages. The resulting samples were tested for the ability to absorb phenol. The phenol content of water after purification with K12 and ShK sorbents decreased from 251.00 to 0.0572 and 0.737 mg/L, respectively.

The dependence of the temperature of minimum electrical resistivity on the size of the mosaic blocks of artificial graphite of GMZ grade based on isotropic coke was calculated. A chain model of the electrical connection of lamellar structural elements (graphite flakes) was used. Compliance of the calculated results with Mason’s empirical formula was shown. Two cases were considered: the case of independence of the dimensions of mosaic blocks and the anisometry of the lamellar structural elements and the case when the dimensions of the mosaic blocks were proportional to the anisometry of the lamellar structural elements.

The results of experimental studies on the selection of modifying additives to binders for the water resistance of fuel briquettes from anthracite culm and coal sludge, which are available in the Rostov oblast, are presented. A comparative study of the influence of modifying additives on the water resistance of manufactured fuel briquettes was carried out. The technical analysis of an experimental batch of fuel briquettes was reported. The mechanism of formation of the structure and properties of fuel briquettes containing various additives was considered.

The colloid-chemical properties of humic acids (HAs) were studied depending on the mechanochemical modification of their structure. An increase in the amount of acidic ionogenic groups and hydrophilic fragments in the composition of modified HAs facilitated a decrease in the excess energy of surface molecules. In an alkaline solution, two types of colloids characterized by a decrease in the energy of adsorption and the constant of adsorption equilibrium were formed as the concentration of HAs was increased.

Humic substances (HSs) extracted from brown coal, peat, and other sources are considered as an efficient and affordable sorbent used to trap and bind heavy metal ions, which are hazardous to the environment. This paper provides an overview of modern works on this subject matter. Typical structural characteristics and properties of HSs and methods for their extraction from brown coal, peat, swamp waters, and other media are described, and quantitative results of a wide range of experiments on the sorption of metal ions by HSs are presented. Significant fluctuations in the measured sorption capacity of HSs in different experiments probably arise not so much due to variations in the elemental composition and structure of HSs extracted from different sources, but they are associated with experimental conditions, such as the acidity (pH) of solution, ionic strength, concentration of metal ions, and concentration of HSs in the solution. In terms of the order of magnitude, the maximum sorption capacity of HSs is comparable to the total concentration of surface carboxyl and hydroxyl groups, and it amounts to several millimoles of metal ions per gram of HSs.

Proximate and ultimate analysis and ¹³C NMR and IR spectroscopy were used to characterize the samples of brown coal from the Tyulgan deposit of the South Ural basin (TBC), the naturally oxidized form of brown coal from the Tisulsky deposit of the Kansk-Achinsk basin (TBCO), and fulvic acids obtained from it. The component composition of bitumen was studied using gas chromatography–mass spectrometry (GC–MS) analysis. Data of a study on the phytostimulating activity of fulvic acids and their mixtures with the saponifiable component of the resin of extraction bitumens in relation to wheat seeds of the Iren variety were presented. It was shown that the use of the saponifiable component of bitumen resins contributed to an increase in the phytostimulating activity.