Exploring the adsorption and diffusion characteristics of tectonic coal at different mass ratios based on the specific surface Gibbs function

2020 ◽  
Vol 376 ◽  
pp. 604-611 ◽  
Author(s):  
Pengxiang Zhao ◽  
Hui Liu ◽  
Shugang Li ◽  
Chun-Hsing Ho ◽  
Lei Qin ◽  
...  
Keyword(s):  
Specific Surface ◽  
Gibbs Function ◽  
Diffusion Characteristics ◽  
Mass Ratios ◽  
Tectonic Coal ◽  
And Diffusion

scholarly journals Experimental and Simulation Studies on Adsorption and Diffusion Characteristics of Coalbed Methane

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3445 ◽  
Author(s):  
Donghyeon Kim ◽  
Youngjin Seo ◽  
Juhyun Kim ◽  
Jeongmin Han ◽  
Youngsoo Lee
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Coalbed Methane ◽  
Equilibrium Time ◽  
Diffusion Characteristics ◽  
Adsorbed Methane ◽  
Cbm Production ◽  
Lump Coal ◽  
And Diffusion

Coalbed methane (CBM) content is generally estimated using the isotherm theory between pressure and adsorbed amounts of methane. It usually determines the maximum content of adsorbed methane or storage capacity. However, CBM content obtained via laboratory experiment is not consistent with that in the in-situ state because samples are usually ground, which changes the specific surface area. In this study, the effect of the specific surface area relative to CBM content was investigated, and diffusion coefficients were estimated using equilibrium time analysis. The differences in adsorbed content with sample particle size allowed the determination of a specific surface area where gases can adsorb. Also, there was an equilibrium time difference between fine and lump coal, because more time is needed for the gas to diffuse through the coal matrix and adsorb onto the surface in lump coal. Based on this, we constructed a laboratory-scale simulation model, which matched with experimental results. Consequently, the diffusion coefficient, which is usually calculated through canister testing, can be easily obtained. These results stress that lump coal experiments and associated simulations are necessary for more reliable CBM production analysis.

Organic Heterojunctions for Photovoltaic Applications: C60 Growth on Pentacene

2010 ◽  
Vol 1263 ◽  
Author(s):  
Rebecca Ann Cantrell ◽  
Paulette Clancy
Keyword(s):  
Atomic Scale ◽  
Short Axis ◽  
Energy Functions ◽  
Potential Energy Functions ◽  
The North ◽  
Diffusion Characteristics ◽  
Static Energy ◽  
Semi Empirical ◽  
Organic Heterojunctions ◽  
And Diffusion

AbstractUsing atomic-scale Molecular Dynamics (MD) and energy minimization techniques in conjunction with semi-empirical MM3 potential energy functions, we consider the adsorption of a C60 molecule on a series of hypothetical pentacene structures that vary only in the tilt of the angle that the short axis of the pentacene molecules makes with the underlying surface (the long axis lying essentially flat, as on a metal substrate). Important relationships were discovered between the angle adopted by the short axis of pentacene on the surface, φ1, and the adsorption and diffusion characteristics of C60. Static energy calculations show that there is a transition of the deepest energy minima from between the pentacene rows at low values of φ1 to within the rows at high values of φ1, where φ1 is the angle the pentacene short axis makes with the surface. MD confirms this trend by the predominant residence locations at the extreme φ1 values. Furthermore, MD results suggest that the C60 traverses the pentacene surface in the east-west direction for lower φ1 values (φ1 ≤ 40°) and in the north-south direction for higher φ1 values (φ1 ≥ 70°). Taking both static and dynamic results together, the most favorable tilt angles for mono-directional nanowire growth should occur between 70° and 80° off-normal.

scholarly journals Experimental Investigation of the Adsorption Characteristics of Mixed Coal and Variations of Specific Surface Areas before and after CH4 Adsorption

2019 ◽  
Vol 9 (3) ◽  
pp. 524 ◽  
Author(s):  
Pengxiang Zhao ◽  
Hui Liu ◽  
Shugang Li ◽  
Haifei Lin ◽  
Yongyong Jia ◽  
...  
Keyword(s):  
Specific Surface ◽  
Laboratory Tests ◽  
Gas Adsorption ◽  
Longwall Face ◽  
Adsorption Volume ◽  
Adsorption Characteristics ◽  
Surface Areas ◽  
Before And After ◽  
Tectonic Coal ◽  
Specific Surface Areas

Tectonic coal is a kind of soft coal that is generated during tectonic movement. Gas outbursts usually occur in seams containing both virgin coal and tectonic coal. To reveal the adsorption characteristics of this type of coal seam (containing both virgin coal and tectonic coal), both tectonic coal and virgin coal were collected from the same longwall face and a series of laboratory tests were conducted, including coal sorption tests and pore specific surface measurements. Both the tectonic coal and virgin coal were crushed into coal powder (0.18–0.25 mm) for the coal sorption tests. In these laboratory tests, different mass ratios between tectonic coal and virgin coal were tested. We found that with the increase of the percentage of tectonic coal, the adsorption volume showed a rising trend, reached its maximum value, and then decreased. The specific surface areas of the mixed coal samples had the same evolution trends as those of the adsorption volume. From the laboratory tests, we found that when the mass ratio of virgin coal to tectonic coal was 1:1, both the adsorption volume and the specific surface areas reached their maximum values. Due to the percentage variation of the tectonic coal in the panel with the advancement of the longwall face, when the tectonic coal accounted for 50% of the total coal, the gas content would rise. Thus, proper measures should be adopted for outburst hazards control. The mathematical model between the change of specific surface area and the stress and strain of pore expansion before and after gas adsorption was established, and the relationship between the change of pore structure and gas emission before and after gas adsorption was obtained. It provides a theoretical basis for further research on coal and gas outburst mechanisms.

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