Effects of sequence stratigraphy on coal characteristics and CH4 adsorption capacity of the low-rank coal in Santanghu Basin, China

The mineral characteristics (occurrence, type, and content) of low-rank coal and their influence on coalbed methane (CBM) reservoirs are investigated at the micro- and nanoscales. Six coal samples of three representative coalmines were used to demonstrate the uniform tectonization from the Zhundong coalfield, NW China. Based on optical microscopy and scanning electron microscopyenergy dispersive spectrum (SEM-EDS) analysis, the mineral composition and occurrence characteristics were discussed. The micro- and nanoscale reservoir characteristics in low-rank coal (pore size distribution and adsorption capability) were studied by diverse methods, including lowtemperature N2 adsorption/desorption, mercury intrusion porosimetry and CH4 isotherm adsorption analysis. The coal reservoir nuclear magnetic T2 spectra of porosity and movable fluid were obtained by combining low-field nuclear magnetic resonance (NMR) analysis, which has an advantage of determining pore fluid technology. The mineral content is highly variable (4˜16 vol.%) in the Xi Heishan prospecting area of the Qitai region. Kaolinite, goyazite, ankerite and anorthosite were microscopically observed to be filling in coal pores and microfractures, and the minerals are given priority to silicate minerals. There is a greater content of mesopores (100–1000 nm) and transition pores (10–100 nm), and they are well connected. The micropores (0–10 nm) are dominated by parallel plate, closed or wedge-shaped pores. Furthermore, the microfractures are mainly observed for types B (width ≥ 5 μm and length≤ 10 mm) and D (width<5 μm and length<300 μm). The results show that microfractures B and C (width< 5 μm and length ≥ 300 μm) are better connected, but the orientation and connectivity of type D are worse. The Langmuir volume and mesopore content decreased with increasing mineral content, which shows that the low-rank coal minerals filled some adsorption space; the reduced CBM adsorption capacity and cellular pore and intergranular pore filled with minerals affect the mesopore content. Therefore, mineral characterization significantly influences methane adsorption capacity and pore structure.

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Hydrogen Adsorption Capacity Reduction of Activated Carbon Produced from Indonesia Low Rank Coal by Pelletizing

Sains Malaysiana ◽

10.17576/jsm-2015-4405-15 ◽

2015 ◽

Vol 44 (5) ◽

pp. 747-752

Author(s):

Sri Harjanto ◽

Latifa N. Noviana ◽

Mia Diniati ◽

Stefanno W. Yunior ◽

Nasaruddin .

Keyword(s):

Activated Carbon ◽

Adsorption Capacity ◽

Hydrogen Adsorption ◽

Low Rank ◽

Low Rank Coal ◽

Capacity Reduction

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Coalbed methane adsorption capacity related to maceral compositions

Energy Exploration & Exploitation ◽

10.1177/0144598719870325 ◽

2019 ◽

Vol 38 (1) ◽

pp. 79-91 ◽

Cited By ~ 1

Author(s):

Langtao Liu ◽

Chao Jin ◽

Lei Li ◽

Chenyang Xu ◽

Pengfei Sun ◽

...

Keyword(s):

Adsorption Capacity ◽

Coalbed Methane ◽

Functional Group ◽

Methane Adsorption ◽

Low Rank ◽

Low Rank Coal ◽

Great Role ◽

Adsorption Volume ◽

Isothermal Adsorption ◽

Enhanced Adsorption

Maceral compositions take a great role in coalbed methane adsorption. Two controversial viewpoints coexist on the effect of maceral compositions to coalbed methane adsorption. One is vitrinite has better adsorption capacity than inertinite and the other is inertinite has enhanced adsorption capacity than vitrinite. In order to clarify this issue, a series of coal samples were collected and highly purified vitrinite and inertinite concentrates were gained by heavy-fluid flotation and centrifugal separation. Isothermal adsorption experiments of methane were performed to these concentrates with equilibrium moisture and their ultimate adsorption volume were obtained finally. The results show that the adsorption capacity of vitrinite is weaker and the capacity of inertinite is stronger for low-rank coal. For high-rank coal, the adsorption capacity of vitrinite is stronger and the capacity of inertinite is weaker. Along with the increase of coal rank, the adsorption capacity of vitrinite rises gradually and the adsorption capacity of inertinite declines little by little. This result shows that the adsorption capacity of coal to methane not only relates to contents of vitrinite and inertinite, but also relates to metamorphic grade of the coal, because with the increase of metamorphism of coal, molecular structure, functional group and pore characteristic of vitrinite and inertinite change gradually, which results in tremendous changes in the adsorption capacity of coal.

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Enrichment of Indonesian Low Rank Coal's Surface Oxygen Compounds (SOCs) Using Hydrogen Peroxide and its Adsorptive Properties

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.896.159 ◽

2014 ◽

Vol 896 ◽

pp. 159-162 ◽

Cited By ~ 3

Author(s):

Galuh Yuliani ◽

Imas Noviyana ◽

Agus Setiabudi

Keyword(s):

Hydrogen Peroxide ◽

Adsorption Capacity ◽

Surface Area ◽

Oxidation Process ◽

Low Rank ◽

Cationic Dye ◽

Surface Oxygen ◽

Low Rank Coal ◽

Batch Tests ◽

Adsorption Capacities

Cheap and highly abundant low rank coal from Banten, West Java, Indonesia, was utilized as an adsorbent for a cationic dye. The previous reports show that raw low rank coal has low adsorption capacity when compared to activated carbon. It is also indicated that the coals surface oxygen compounds played a major role in the adsorption mechanism. This research aimed to enrich the oxygen compounds on the coals surface by a straightforward oxidation process using hydrogen peroxide and to investigate the adsorption capacities of raw and treated coals using cationic dye solutions. The oxidation process was conducted by adding the raw coal in hydrogen peroxide solutions having concentrations of 5%, 10%, and 20%, followed by stirring for 10 minutes to 60 minutes. After a serial of washing processes and air-drying, the adsorption capacities of the treated coals for a cationic dye were investigated using batch tests. The batch tests were conducted by adding 0.1 to 0.3 g of coals to 50 mL of methylene blue solutions followed by stirring the solutions for 5 hours. The experimental data were plotted using Langmuir adsorption isotherm model. The adsorption capacity of a treated coal when plotted using Langmuir isotherm was found to be 103 mg/g, significantly higher than that of the raw coal, which was only 52 mg/g. The FTIR spectra showed new absorption of carboxylates at 1700 cm-1 indicating increases in the oxygen containing groups, whilst the surface area measurement indicated an increase in surface area from 0.097 m2/g to 0.232 m2/g. It is concluded that the treatment using hydrogen peroxide solution has significantly improved the surface oxygen compounds of the low rank coal, increased its surface area and also its adsorption capacity for a cationic dye.

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INVESTIGATING A LINK BETWEEN LOW-RANK COAL BEARING CARRIZO-WILCOX AQUIFER WATER AND KIDNEY DISEASE IN EAST TEXAS

10.1130/abs/2018am-324830 ◽

2018 ◽

Author(s):

Jayeeta Chakraborty ◽

◽

Robert B. Finkelman ◽

William H. Orem ◽

Matthew S. Varonka ◽

...

Keyword(s):

Kidney Disease ◽

Low Rank ◽

East Texas ◽

Low Rank Coal

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Microfacies and depositional environment of Tertiary Tanjung Enim low rank coal, South Sumatra Basin, Indonesia

International Journal of Coal Geology ◽

10.1016/j.coal.2004.07.004 ◽

2005 ◽

Vol 61 (3-4) ◽

pp. 197-221 ◽

Cited By ~ 56

Author(s):

Hendra Amijaya ◽

Ralf Littke

Keyword(s):

Depositional Environment ◽

Low Rank ◽

Low Rank Coal

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Surface Chemical Heterogeneity of Low Rank Coal Characterized by Micro-FTIR and Its Correlation with Hydrophobicity

Minerals ◽

10.3390/min11030239 ◽

2021 ◽

Vol 11 (3) ◽

pp. 239

Author(s):

Wei Wang ◽

Long Liang ◽

Yaoli Peng ◽

Maria Holuszko

Keyword(s):

Surface Chemistry ◽

Functional Group ◽

Group Composition ◽

Contact Angles ◽

Low Rank ◽

Surface Chemical ◽

Carbonyl Groups ◽

Low Rank Coal ◽

Different Types ◽

Aliphatic Carbon

Micro-Fourier transform infrared (micro-FTIR) spectroscopy was used to correlate the surface chemistry of low rank coal with hydrophobicity. Six square areas without mineral impurities on low rank coal surfaces were selected as testing areas. A specially-designed methodology was applied to conduct micro-FTIR measurements and contact angle tests on the same testing area. A series of semi-quantitative functional group ratios derived from micro-FTIR spectra were correlated with contact angles, and the determination coefficients of linear regression were calculated and compared in order to identify the structure of the functional group ratios. Finally, two semi-quantitative ratios composed of aliphatic carbon hydrogen, aromatic carbon hydrogen and two different types of carbonyl groups were proposed as indicators of low rank coal hydrophobicity. This work provided a rapid way to predict low rank coal hydrophobicity through its functional group composition and helped us understand the hydrophobicity heterogeneity of low rank coal from the perspective of its surface chemistry.

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