Solid Fuel Chemistry最新文献

The article presents the results of a study of asphaltenes isolated from the liquid products of initiated cracking of two tar samples at 500°C in the presence of a calcium acetate additive. Characteristic changes in the composition of cracking products depending on the amount of the additive were shown. It was established that the formation of solid condensation products depended not only on the initial concentration of asphaltenes but also on their structure. Changes in the structural-group parameters of asphaltenes in the course of the initiated cracking of tars were studied. A distinctive feature of tar cracking in the presence of calcium acetate was that the additive promoted both the destruction of structural blocks and a significant decrease in their number in the composition of asphaltene molecules. In addition, the averaged asphaltene molecules became more compact due to the destruction of aliphatic substituents and naphthenic rings, and the fraction of condensed aromatic structures in their composition increased significantly.

In order to better understand the microstructure characteristics of soft and hard coal and its influence on gas adsorption capacity, three groups of soft and hard coal samples with different maturities were collected for measurements from Ordos Basin. CH₄ isothermal adsorption experiments were performed to analyze the gas adsorption characteristics. Pore distribution and oxygen-containing groups of these soft and hard coals were detected by low-pressure N₂ adsorption and Fourier Transform Infrared Spectroscopy (FTIR), respectively. For the collected FTIR spectrum, the peak-fitting method is used to semi-quantitatively study the distribution of oxygen-containing groups. Comparison of microstructure characteristics and methane adsorption capacity has also been made between soft and hard coal samples. The results showed that soft coals has smaller pore diameter and the micropore and mesopore surface area is 43.2–75.1 and 12.2–41.1% greater than that of corresponding hard coal, respectively, but the macropore surface area is 18.9–66.7% less than that of hard coals. The aromaticity of hard bituminous coals is smaller than that of the corresponding soft coals, while the peak areas of carbonyl and hydroxyl groups are obviously larger than that of the corresponding soft bituminous coals. However, the distribution of oxygen-containing groups in soft and hard anthracite exhibits the opposite trend. Tectonic deformation contributes to the decline of oxygen-containing groups and can enhance the maturity and pore surface area of bituminous coals, exhibiting superior methane adsorption property compared with hard bituminous coals. Though soft anthracite has developed micropore/mesopore structures, its lower maturity and higher content of oxygen-containing groups lead to the decline of gas adsorption capacity. Gas adsorption behaviors of coal are closely related to the complex microstructures, and the combined effects of physical structures and chemical groups should be taken into account.

The kinetics of adsorption of 3,5,6-trichloro-4-aminopicric acid (picloram) on mesoporous activated carbon Sibunit was studied. The mass of the adsorbent for effective extraction of picloram from an aqueous solution was determined by carrying out adsorption with different ratios of the adsorbent mass to the volume of the adsorbate solutions of different concentrations. It was found that time is also an important parameter for effective adsorption.

Enhancing the performance of PEMFCs significantly depends on the efficient diffusion of gases and the transport of water molecules. In this study, we utilized the high porosity and electrical conductivity of carbon fiber to promote the autonomous growth of lotus leaf graphene along the carbon fiber substrate. This innovation enables the creation of a gas cathode microporous layer for aspirated PEMFCs, which demonstrates high structural stability, minimal mass transfer resistance, and cost-effectiveness. Efficient gas diffusion and water transport are critical, as inadequate management of these factors can negatively impact battery lifespan and stability. The PEMFC cell with Gra/CC-60 exhibits a maximum current density of 1480 mA/cm², outperforming other samples. Additionally, the peak power density reaches 398.9 mW/cm² at 0.43 V. Remarkably, after 12 hours of operation at high current density, the PEMFC cell shows only a 7.94% drop in current density. This research paves the way for the development of microporous layers for fuel cells, sensors, and catalytic modules, while also introducing a novel approach to the selection and design of carbon materials.

To investigate the influence of water content on coal combustion characteristics, bituminous coal was collected as the research target from the Wusitai Coal Mine. The combustion characteristic parameters of coal samples with various water contents were measured by cone calorimeter, and the combustion efficiency of coal samples was analyzed. The spontaneous combustion characteristics of samples are significantly affected by moisture within coal. As the rise of moisture content, the ignition time of bituminous coal is firstly reduced and then it is enhanced. The coal sample with moisture content of 10.36% has the fastest ignition. The total smoke discharge, the peak heat release rate and the flue gas generation rate of bituminous coal samples are firstly decreased, then increased and finally reduced with the increase of water content. In the later stage of combustion, the CO generation rate is the smallest for the bituminous sample with water content of 6.59%, while it is the largest for the sample with 18.78% content of moisture. Large moisture content makes the coal sample incomplete combustion, which can improve the CO production rate. The combustion efficiency of bituminous coal can be improved by the appropriate moisture content. It was found that the total CO generation rate, smoke release rate and the ignition time are effectively reduced, after setting the moisture content of 6.59–10.36% of the coal. As a result, both the combustion efficiency and heat release rate are improved.

In order to effectively prevent and control the gas disaster during the mining of deep coal rock bodies and improve the extraction efficiency, this paper carries out the research on the coal microstructure, gas seepage and the characteristic parameters of the coal rock bodies by means of scanning electron microscopy and low-temperature liquid nitrogen adsorption test, and adopts a combination of numerical simulation and on-site engineering validation to study the stress distribution around the surrounding rock after excavation, the range of fracture zone and plastic zone generated by the coal rock around the drill hole to optimise the design parameters of gas extraction in the mining area, by using FLAC 3D and COMSOL Multiphysics. The stress distribution around the surrounding rock after excavation, and the range of fracture and plasticity zones generated in the coal rock around the drill holes, in order to optimise the design parameters of gas extraction in the mine. The study shows that: with the increasing of lateral pressure coefficient, the stress concentration phenomenon in the roadway evolves into vertical symmetrical distribution, the working face of the test mine coal seam crushing area ranges from 0 to 5m, the coal seam plastic area ranges from 12 to 16 m, the stress concentration area ranges from 8 to 24 m, and the original stress area is after 24 m, and the depth of drilling hole reaches the peak of the stress at 16 m, and the drill cuttings method is adopted on the site to verify the simulation results, and then it is decided to determine the reasonable sealing depth of 2#coal seam in the test mine. After verifying the simulation results by drilling chip volume method on site, it is determined that the reasonable sealing depth of the test mine 2# seam is 16 m.

Gas adsorption capacity of coals is one of basic characteristics of coal. Oxygen adsorbed by coal leads to spontaneous combustion. The adsorption capacities of coal samples from the Karadon Region of Zonguldak were determined for nitrogen, methane and carbon dioxide gases. Gas contents and gas adsorption capacities for Karadon coals were correlated.

China is endowed with abundant coal reserves, yet it remains heavily reliant on oil and natural gas imports. Pyrolysis of coal into gas and oil products presents a promising solution to address China’s energy security concerns. Co-pyrolysis of coal and plastic can enhance the production of liquid and gas products. Thermogravimetric experiments were conducted to explore the effects of mixing ratio, coal type (bituminous and anthracite), and plastic type (polystyrene PS and polyethylene PE) on the co-pyrolysis of coal and plastic. The results showed that the interaction during the co-pyrolysis of coal and plastic occurred mainly in the temperature interval of plastic weight loss and contributed to the increase of pyrolytic conversion. Compared to theoretical calculations, conversion rates of coal/plastic blenders co-pyrolysis can be improved mostly at blending ratios of 50% PS and 75% PE, achieving increases of 7.9–8.9% and 4.2–7.2% for PS/coal and PE/coal at 800°C respectively. The synergistic effect of coal type on co-pyrolysis is influenced by both the blending ratio and the plastic type used. So does plastic type. Finally, the kinetic analysis of co-pyrolysis was carried out. It is found different weight loss stage of co-pyrolysis processes can be expressed by first order reaction.

This article presents the results of studies on the noble metal contents of the Paleozoic dictyonema shales of the Baltic sedimentary basin. On the territory of the studied Kaibolovo–Gostilitsy prospecting area, high, up to potentially industrial, concentrations of noble platinum group metals (PGMs), comparable with the concentrations in sedimentary ore types taken into account by the State Balance of Mineral Reserves of the Russian Federation, have been confirmed with a large factual material (more than 600 shale samples). Increased gold and silver contents have also been noted. Palladium predominated in the composition of platinum group metals. The article presents the identified features of the PGM distribution over the area and in the section of the shale-bearing sedimentary strata. Precious metals in the dictyonema shales of the Baltic basin are distributed in the shales in the following forms: in terrigenous scattered finely dispersed native minerals (forms), in impurities in sulfide minerals (mainly in pyrite), and in species localized in the organic matter (Ag and partly Au). The conditions of formation of precious metal mineralization in the dictyonema shales have been reconstructed. The source of precious metals were rocks of the provenance area—the Baltic Shield—and seawater of the ancient sedimentation area, a supplier of a number of rare metals deposited on the geochemical reducing barrier of the dictyonema shales. Increased and stable concentrations of precious metals in combination with large-scale (billions of tons) geological resources of the dictyonema shales indicated the possible presence of a large unconventional mineral resource base of precious metals in the Baltic region of Russia.

Briquetting is a crucial component of clean coal technology. Pulverized coal from Naomao Lake coal mine in Hami area was selected as experimental sample to investigate the effects of binder and moisture content on briquette quality. The results show that binders can enhance relax density, compressive strength, hydrophobicity and durability. And, binder type has a significant impact on energy consumption during briquetting process. For cement and clay, as addition ratio increases, briquetting energy consumption also increases. For bentonite and sodium humate, addition ratio has a small impact on briquetting energy consumption. In addition, compressive strength, hydrophobicity and durability of briquettes gradually increase with the enhancement of moisture content. Moisture can provide effective lubrication during moulding process, reducing friction between raw materials and between raw materials and mold. Afterward, by using the PCA method, a new comprehensive evaluation index was established to investigate the influence of binder type and binder ratio on the quality characteristics of pulverized coal briquetting. The results show that comprehensive evaluation index of briquettes gradually increases with the enhancement of binder ratio, and the briquette containing 15% sodium humate has the highest comprehensive evaluation index, which confirms the reliability of the proposed evaluation method for briquette quality.