scholarly journals Contribution of Ash Content Related to Methane Adsorption Behaviors of Bituminous Coals

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yanyan Feng ◽  
Wen Yang ◽  
Wei Chu
Keyword(s):  
Adsorption Capacity ◽  
Coalbed Methane ◽  
Textural Properties ◽  
Isosteric Heat ◽  
Micropore Volume ◽  
Ash Content ◽  
Heat Of Adsorption ◽  
Methane Adsorption ◽  
Adsorbed Phase ◽  
Adsorption Processes

Methane adsorption isotherms on coals with varying ash contents were investigated. The textural properties were characterized by N2adsorption/desorption isotherm at 77 K, and methane adsorption characteristics were measured at pressures up to 4.0 MPa at 298 K, 313 K, and 328 K, respectively. The Dubinin-Astakhov model and the Polanyi potential theory were employed to fit the experimental data. As a result, ash content correlated strongly to methane adsorption capacity. Over the ash range studied, 9.35% to 21.24%, the average increase in methane adsorption capacity was 0.021 mmol/g for each 1.0% rise in ash content. With the increasing ash content range of 21.24%~43.47%, a reduction in the maximum adsorption capacities of coals was observed. In addition, there was a positive correlation between the saturated adsorption capacity and the specific surface area and micropore volume of samples. Further, this study presented the heat of adsorption, the isosteric heat of adsorption, and the adsorbed phase specific heat capacity for methane adsorption on various coals. Employing the proposed thermodynamic approaches, the thermodynamic maps of the adsorption processes of coalbed methane were conducive to the understanding of the coal and gas simultaneous extraction.

scholarly journals Changes in Pore Structure of Coal Caused by CS2 Treatment and Its Methane Adsorption Response

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Run Chen ◽  
Yong Qin ◽  
Pengfei Zhang ◽  
Youyang Wang
Keyword(s):  
Pore Structure ◽  
Adsorption Capacity ◽  
Gas Adsorption ◽  
Recovery Process ◽  
Micropore Volume ◽  
Methane Adsorption ◽  
Coal Bed ◽  
Methane Recovery ◽  
Before And After ◽  
Key Issues

The pore structure and gas adsorption are two key issues that affect the coal bed methane recovery process significantly. To change pore structure and gas adsorption, 5 coals with different ranks were treated by CS2 for 3 h using a Soxhlet extractor under ultrasonic oscillation conditions; the evolutions of pore structure and methane adsorption were examined using a high-pressure mercury intrusion porosimeter (MIP) with an AutoPore IV 9310 series mercury instrument. The results show that the cumulative pore volume and specific surface area (SSA) were increased after CS2 treatment, and the incremental micropore volume and SSA were increased and decreased before and after Ro,max=1.3%, respectively; the incremental big pore (greater than 10 nm in diameter) volumes were increased and SSA was decreased for all coals, and pore connectivity was improved. Methane adsorption capacity on coal before and after Ro,max=1.3% also was increased and decreased, respectively. There is a positive correlation between the changes in the micropore SSA and the Langmuir volume. It confirms that the changes in pore structure and methane adsorption capacity due to CS2 treatment are controlled by the rank, and the change in methane adsorption is impacted by the change of micropore SSA and suggests that the changes in pore structure are better for gas migration; the alteration in methane adsorption capacity is worse and better for methane recovery before and after Ro,max=1.3%. A conceptual mechanism of pore structure is proposed to explain methane adsorption capacity on CS2 treated coal around the Ro,max=1.3%.

scholarly journals CO2 and CH4 Adsorption Behavior of Biomass-Based Activated Carbons

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3136 ◽  
Author(s):  
Deneb Peredo-Mancilla ◽  
Imen Ghouma ◽  
Cecile Hort ◽  
Camelia Matei Ghimbeu ◽  
Mejdi Jeguirim ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Activated Carbon ◽  
Adsorption Capacity ◽  
Gas Adsorption ◽  
Activated Carbons ◽  
Chemical Activation ◽  
Textural Properties ◽  
Micropore Volume ◽  
Activation Method ◽  
Physical Activation

The aim of the present work is to study the effect of different activation methods for the production of a biomass-based activated carbon on the CO 2 and CH 4 adsorption. The influence of the activation method on the adsorption uptake was studied using three activated carbons obtained by different activation methods (H 3 PO 4 chemical activation and H 2 O and CO 2 physical activation) of olive stones. Methane and carbon dioxide pure gas adsorption experiments were carried out at two working temperatures (303.15 and 323.15 K). The influence of the activation method on the adsorption uptake was studied in terms of both textural properties and surface chemistry. For the three adsorbents, the CO 2 adsorption was more important than that of CH 4 . The chemically-activated carbon presented a higher specific surface area and micropore volume, which led to a higher adsorption capacity of both CO 2 and CH 4 . For methane adsorption, the presence of mesopores facilitated the diffusion of the gas molecules into the micropores. In the case of carbon dioxide adsorption, the presence of more oxygen groups on the water vapor-activated carbon enhanced its adsorption capacity.

Surface Modification of Activated Carbon and its Effects on Methane Adsorption

2013 ◽  
Vol 395-396 ◽  
pp. 605-609
Author(s):  
Shi Xiong Hao ◽  
Zu Xiao Yu ◽  
Xing Yong Liu
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Micropore Volume ◽  
Methane Adsorption ◽  
Surface Oxygen Groups ◽  
Two Samples ◽  
Boehm Titration ◽  
Adsorption Data ◽  
Oxygen Groups ◽  
Oxygen Surface

In this work, one activated carbon (AC) was modified with H2O2, (NH4)2S2O8saturated solution and H2SO4/(NH4)2S2O8mixture respectively. The oxygen groups on ACs surface were characterized by Boehm titration. The textures of the ACs were investigated by N2adsorption at 77 K. The influence of surface oxygen groups on methane adsorption on ACs has been studied. The results of Boehm titration showed that the concentration of acidic oxygen functional groups on the AC surface increased after modification. N2adsorption data showed that the specific surface areaSBETand the micropore volumeVmicof AC were changed lightly after modification. It was observed that there was, in general, a positive correlation between the methane saturated adsorption capacity and theSBETof ACs while a negative correlation between methane saturated adsorption capacity and the total surface acidic groups. The methane saturated adsorption capacity was determined by the ACs surface chemistry when the microporosity parameters of two samples were similar. AC with a higher amount of oxygen surface groups, and consequently with a less hydrophobic character, had lower methane adsorption capacity.

scholarly journals Application of a Modified Low-Field NMR Method on Methane Adsorption of Medium-Rank Coals

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xiaozhen Chen ◽  
Taotao Yan ◽  
Fangui Zeng ◽  
Yanjun Meng ◽  
Jinhua Liu
Keyword(s):  
Adsorption Capacity ◽  
Coalbed Methane ◽  
Gas Adsorption ◽  
Vitrinite Reflectance ◽  
Methane Adsorption ◽  
Coal Rank ◽  
Nmr Method ◽  
Low Field ◽  
Low Field Nmr ◽  
The Absolute

Methane adsorption capacity is an important parameter for coalbed methane (CBM) exploitation and development. Traditional examination methods are mostly time-consuming and could not detect the dynamic processes of adsorption. In this study, a modified low-field nuclear magnetic resonance (NMR) method that compensates for these shortcomings was used to quantitatively examine the methane adsorption capacity of seven medium-rank coals. Based on the typical T 2 amplitudes obtained from low-field NMR measurement, the volume of adsorbed methane was calculated. The results indicate that the Langmuir volume of seven samples is in a range of 18.9–31.85 m3/t which increases as the coal rank increases. The pore size in range 1-10 nm is the main contributor for gas adsorption in these medium-rank coal samples. Comparing the adsorption isotherms of these coal samples from the modified low-field NMR method and volumetric method, the absolute deviations between these two methods are less than 1.03 m3/t while the relative deviations fall within 4.76%. The absolute deviations and relative deviations decrease as vitrinite reflectance ( R o ) increases from 1.08% to 1.80%. These results show that the modified low-field NMR method is credible to measure the methane adsorption capacity and the precision of this method may be influenced by coal rank.

scholarly journals Coalbed methane adsorption capacity related to maceral compositions

2019 ◽  
Vol 38 (1) ◽  
pp. 79-91 ◽  
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.

scholarly journals Methane adsorption characteristics and its influencing factors of the medium-to-high rank coals in the Anyang-Hebi coalfield, northern China

2018 ◽  
Vol 37 (1) ◽  
pp. 60-82 ◽  
Author(s):  
Sheng Zhao ◽  
Longyi Shao ◽  
Haihai Hou ◽  
Yue Tang ◽  
Zhen Li ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Influencing Factors ◽  
Coalbed Methane ◽  
Vitrinite Reflectance ◽  
Negative Relationship ◽  
Methane Adsorption ◽  
High Rank ◽  
Gas Content ◽  
Coal Rank ◽  
Adsorption Characteristics

The variation of coal rank in the Anyang-Hebi (Anhe) coalfield has the phenomenon of anti-Hilt law, which makes the coalfield distinctive for coalbed methane exploration research. The methane adsorption characteristics and influencing factors of the medium-to-high rank coal samples of the Shanxi Formation in this coalfield were analyzed. The results indicate that the Langmuir volume ( VL) of coals in the shallow western part of the Anhe coalfield is generally higher than that in the deep eastern part. The coal rank and the coal macerals are the dominant factors that influence the methane adsorption capacity of coals in this anti-Hilt law area. The methane adsorption capacity, represented by VL, first increases and then decreases with the coal rank, and the highest VL value corresponds to the maximum vitrinite reflectance of ∼2.1%. The adsorption capacity has a positive correlation with the vitrinite and the moisture content, a negative relationship with the inertinite content. In general, the adsorption capacity of coal samples shows a “V-shaped” change with the ash yield, and the lowest VL value corresponds to the ash yield of ∼9%. A prediction model of the gas content of the Anhe coalfield was proposed based on changes of the methane adsorption capacity and principal component analysis. Areas with a critical depth ranging from 400 m to 700 m are suggested to be methane enrichment regions for coalbed methane exploration in the Anhe coalfield.

scholarly journals Molecular Simulation of Hydrogen Storage in Ion-Exchanged X Zeolites

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Xiaoming Du
Keyword(s):  
Adsorption Capacity ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Adsorption Sites ◽  
Hydrogen Molecules ◽  
Adsorption Temperature ◽  
X Zeolites ◽  
Cation Type ◽  
Simulated Distribution

Grand Canonical Monte Carlo (GCMC) method was employed to simulate the adsorption properties of molecular hydrogen on ion-exchanged X zeolites at 100–293 K and pressures up to 10 MPa in this paper. The effect of cation type, temperature, and pressure on hydrogen adsorption capacity, heat of adsorption, adsorption sites, and adsorption potential energy of ion-exchanged X zeolites was analyzed. The results indicate that the hydrogen adsorption capacity increases with the decrease in temperatures and the increase in pressures and decreases in the order ofKX<LiX<CaX. The isosteric heat of adsorption for all the three zeolites decreases appreciably with the increase in hydrogen adsorption capacity. The hydrogen adsorption sites in the three zeolites were determined by the simulated distribution of hydrogen adsorption energy and the factors that influence their variations were discussed. Adsorption temperature has an important effect on the distribution of hydrogen molecules in zeolite pores.

The Isosteric Heat of Adsorption of Sr2+, Ce3+, Sm3+, Gd3+, Th4+ and UO22+ Ions on Activated Charcoal

1994 ◽  
Vol 11 (4) ◽  
pp. 201-208 ◽  
Author(s):  
Riaz Qadeer ◽  
Javed Hanif
Keyword(s):  
Activation Energy ◽  
Activated Charcoal ◽  
Physical Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Clapeyron Equation ◽  
Temperature Changes ◽  
Isosteric Heat Of Adsorption ◽  
Adsorption Processes ◽  
Increasing Temperature

The values of the isosteric heat of adsorption (qst) of Sr2+, Ce3+, Sm3+, Gd3+, Th4+ and UO22+ ions on activated charcoal have been calculated at different surface coverages and temperatures by applying the Clausius–Clapeyron equation. The variation of qst with surface coverage indicates the heterogeneous nature with varying activities of the activated charcoal surface. The behaviour of qst values with temperature suggests that two types of adsorption processes occur simultaneously; one with a small activation energy and the other with a large activation energy. A large increase in the qst values indicates that increasing temperature changes the physical adsorption process to chemisorption.

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