scholarly journals Molecular simulation of gases competitive adsorption in lignite and analysis of original CO desorption

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jing Zhang ◽  
Jiren Wang ◽  
Chunhua Zhang ◽  
Zongxiang Li ◽  
Jinchao Zhu ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Molecular Simulation ◽  
Competitive Adsorption ◽  
Air Leakage ◽  
Adsorption Characteristics ◽  
Adsorption Sites ◽  
Simulation Based ◽  
Lignite Coal ◽  
Model C ◽  
Grand Canonical

AbstractTo study the adsorption characteristics of CO, CO2, N2, O2, and their binary-components in lignite coal, reveal the influence of CO2 or N2 injection and air leakage on the desorption of CO in goafs, a lignite model (C206H206N2O44) was established, and the supercell structure was optimized under temperatures of 288.15–318.15 K for molecular simulation. Based on molecular dynamics, the Grand Canonical Monte Carlo method was used to simulate the adsorption characteristics and the Langmuir equation was used to fit the adsorption isotherms of gases. The results show that for single-components, the order of adsorption capacity is CO2 > CO > O2 > N2. For binary-components, the competitive adsorption capacities of CO2 and CO are approximate. In the low-pressure zone, the competitive adsorption capacity of CO2 is stronger than that of CO, and the CO is stronger than N2 or O2. From the simulation, it can be seen that CO2, N2 or O2 will occupy adsorption sites, causing CO desorption. Therefore, to prevent the desorption of the original CO in the goaf, it is not suitable to use CO2 or N2 injection for fire prevention, and the air leakage at the working faces need to be controlled.

scholarly journals Research on adsorption characteristics of H2S, CH4, N2 in coal based on Monte Carlo method

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiren Wang ◽  
Cong Ding ◽  
Dameng Gao ◽  
Hongpeng Liu
Keyword(s):  
Monte Carlo ◽  
Adsorption Capacity ◽  
Adsorption Process ◽  
Water Molecules ◽  
Structure Model ◽  
Grand Canonical Monte Carlo ◽  
Adsorption Characteristics ◽  
Adsorption Sites ◽  
Influence Of Temperature On ◽  
Grand Canonical

AbstractIn order to study the adsorption characteristics of H2S, CH4 and N2 by coal under different conditions, the new macromolecular structure model of Dongqu No. 2 was constructed, and the grand canonical Monte Carlo (GCMC) method was used to simulate the adsorption process of three types of gases in coal. The dependence of adsorption capacity of coal on its temperature, pressure and moisture content was analyzed. The results show that with the increase of pressure and temperature, adsorption isotherms of all the three gases follow Langmuir model. For pressure greater than 2 MPa, the influence of temperature on adsorption capacity was greater than that of pressure. With rise in temperature, the decrease in rate of H2S adsorption was least and drops in the heat of adsorption of H2S most. This indicates that the adsorption of H2S on coal is more stable than those of CH4 and N2. As the water content of coal increased, its adsorption capacity for the present three gases decreased linearly, and the capacity for H2S (1.77 mmol/g) changed the most. The reduction of free volume linearly and preferential occupation of adsorption sites by water molecules are the main reasons for the highest change in the adsorbed amount of H2S gas.

scholarly journals Numerical Simulation of Adsorption of Organic Inhibitors on C-S-H Gel

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 742
Author(s):  
Zijian Song ◽  
Huanchun Cai ◽  
Qingyang Liu ◽  
Xing Liu ◽  
Qi Pu ◽  
...  
Keyword(s):  
Competitive Adsorption ◽  
Cement Hydration ◽  
Grand Canonical Monte Carlo ◽  
Binding Ability ◽  
Liquid Environment ◽  
Adsorption Characteristics ◽  
Organic Inhibitors ◽  
Gcmc Simulations ◽  
Molecule Dynamics ◽  
Grand Canonical

Corrosion inhibitors are one of the most effective anticorrosion techniques in reinforced concrete structures. Molecule dynamics (MD) was usually utilized to simulate the interaction between the inhibitor molecules and the surface of Fe to evaluate the inhibition effect, ignoring the influence of cement hydration products. In this paper, the adsorption characteristics of five types of common alkanol-amine inhibitors on C-S-H gel in the alkaline liquid environment were simulated via the MD and the grand canonical Monte Carlo (GCMC) methods. It is found that, in the MD system, the liquid phase environment had a certain impact on the adsorption configuration of compounds. According to the analysis of the energy, the binding ability of MEA on the surface of the C-S-H gel was the strongest. In the GCMC system, the adsorption of MEA was the largest at the same temperature. Furthermore, for the competitive adsorption in the GCMC system, the adsorption characteristics of the inhibitors on the C-S-H gel were to follow the order: MEA>DEA>TEA>NDE>DETA. Both MD and GCMC simulations confirmed that the C-S-H gel would adsorb the organic inhibitors to a different extent, which might have a considerable influence on the organic inhibitors to exert their inhibition effects.

Molecular simulation of CH4/CO2/H2O competitive adsorption on low rank coal vitrinite

2017 ◽  
Vol 19 (27) ◽  
pp. 17773-17788 ◽  
Author(s):  
Song Yu ◽  
Jiang Bo ◽  
Li Wu
Keyword(s):  
Monte Carlo ◽  
Density Function ◽  
Molecular Simulation ◽  
Competitive Adsorption ◽  
Function Theory ◽  
Density Function Theory ◽  
Low Rank ◽  
Grand Canonical Monte Carlo ◽  
Low Rank Coal ◽  
Grand Canonical

The competitive adsorptions of CH4/CO2/H2O on coal vitrinite (DV-8, C214H180O24N2) were computed based on density function theory (DFT) and grand canonical Monte Carlo (GCMC).

scholarly journals Adsorption of Reactive Brilliant Blue XBR onto Polymeric Adsorbents from Single- and Binary-Solute Solutions

2005 ◽  
Vol 23 (3) ◽  
pp. 235-244 ◽  
Author(s):  
Lu Zhaoyang ◽  
Long Chao ◽  
Li Aimin ◽  
Jiang Zhenmao ◽  
Liu Wei ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Competitive Adsorption ◽  
Brilliant Blue ◽  
Adsorption Selectivity ◽  
Polymeric Adsorbent ◽  
Ionic Polymer ◽  
Adsorption Sites ◽  
Adsorption Capacities ◽  
Direct Competition ◽  
Polymer Adsorbent

A non-ionic polymer adsorbent (NPA) and its aminated polymeric adsorbent (APA) were prepared and characterized towards adsorption from aqueous solution. Two adsorbates, Reactive Brilliant Blue XBR and 2,4-diaminobenzene sulphonic acid (ABSA), were chosen as adsorbates for competitive adsorption from single-solute solution and binary-solute systems onto the two adsorbents prepared. The results showed that APA, the polymer obtained after amination, exhibited a higher adsorption capacity than NPA towards XBR from the single-solute solution. However, in binary-solute solution adsorption, the presence of ABSA reduced the adsorption capacity towards XBR due to direct competition between XBR and ABSA for the same adsorption sites. This resulted in similar adsorption capacities towards XBR for NPA and APA. Moreover, the adsorption selectivity coefficients obtained for XBR onto ABSA in simultaneous adsorption tests suggested that NPA exhibited more favourable adsorption properties towards the adsorption of XBR from binary-solute systems than APA.

CH4 and CO2 Adsorption Mechanism in Kaolinite Slit Nanopores as Studied by the Grand Canonical Monte Carlo Method

2021 ◽  
Vol 21 (1) ◽  
pp. 108-119
Author(s):  
Chenxi Xu ◽  
Haitao Xue ◽  
Qi Dong ◽  
Shuangfang Lu ◽  
Guohui Chen ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Adsorption Capacity ◽  
Quadrupole Moment ◽  
Shale Gas ◽  
Adsorption Mechanism ◽  
Gas Adsorption ◽  
Van Der Waals Forces ◽  
Grand Canonical Monte Carlo ◽  
Adsorption Sites ◽  
Grand Canonical

To confirm the rules and transformation conditions of shale gas adsorption and establish a model for evaluating the adsorption capacity of shale gas quantitatively, it is necessary to reveal the shale gas adsorption mechanism. The adsorption mechanism of CH4 and CO2 in Kaolinite slit nanopores has been studied under the simulated conditions of 90 °C and 30 or 50 MPa by the grand canonical Monte Carlo (GCMC) method. The results indicate that CH4 is controlled only by the Van der Waals forces on the mineral surface because CH4 is nonpolar, while CO2 is controlled by both Van der Waals forces and Coulomb forces due to a certain electric quadrupole moment, which makes the adsorption capacity of CO2 on kaolinite greater than that of CH4. Due to the overlapping adsorption potential on the kaolinite surface of micropores (1 nm), the peak of the density profile is higher in the micropores than the peak in the mesopores (4 nm), resulting in the filling effect in the micropores. On the surface of the silicon-oxygen octahedron, the adsorption site for CH4 and CO2 is in the center of the silicone hexagon-ring, and CO2 with a quadrupole moment shifts near the polar oxygen atoms. In contrast, the adsorption sites of CH4 are relatively dispersed on the surface of the aluminum-oxygen octahedron with a hydroxyl group, while the adsorption sites of CO2 are concentrated in the location of the aggregated oxygen atoms. When CH4 and CO2 coexist, CO2 tends to be adsorbed prior to CH4. With the proportion of CO2 increasing, the competitive adsorption effect is gradually aggravated, which suggests the rationality of injecting CO2 to improve the recovery efficiency of shale gas. These findings can provide theoretical support for shale gas exploration and development.

Competitive adsorption of organic solvents using modified and unmodified calcium bentonite clay mineral

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Organic Solvents ◽  
Competitive Adsorption ◽  
Correlation Factor ◽  
Isotherm Model ◽  
Isotherm Models ◽  
High Concentration ◽  
Dual Purpose ◽  
Calcium Bentonite

Dodecyltrimethylammonium bromide (DTAB)–modified and unmodified calcium bentonite were both used for the competitive adsorption of aromatics (xylene, ethylbenzene and toluene) and petroleum products (gasoline, dual purpose kerosene and diesel) from their aqueous solution. Infrared spectroscopy (IR) and expansion tests (adsorption capacity and Foster swelling) measurement were performed in order to evaluate the performance of the adsorbents. The Foster swelling index and adsorption capacity of the DTAB modified calcium bentonite in the organic solvents follow the trend: xylene > ethylbenzene > toluene > gasoline > dual purpose kerosene (DPK) > diesel > water. However, the adsorption capacity of the adsorbent in diesel outweighed the adsorption capacity in DPK at high concentration of DTAB indicating that diesel has higher affinity for high DTAB concentration than DPK. The percentage removal of the solvent is directly proportional to the concentration of DTAB used in modifying the bentonite as well as the contact time between the adsorbent and the solvent, hence modified calcium bentonite adsorbed a higher percentage of organic solvents than the unmodified calcium bentonite. The adsorption characteristics of both adsorbents improved remarkably after proper agitation of the organic solvents, the unmodified calcium bentonite however adsorbed more water than the modified bentonite. Data obtained from adsorption isotherm models confirms that Freundlich adsorption isotherm model was favored more than Langmuir adsorption isotherm model with the correlation factor (R2) of the former tending more towards unity. The adsorption of ethylbenzene using DTAB modified and unmodified calcium bentonites follow a pseudo second order kinetics mechanism, suggesting that the rate determining step of adsorption involves both the adsorbent and the organic solvent.

scholarly journals Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

2021 ◽  
Author(s):  
Shangbin Chen ◽  
Chu Zhang ◽  
Xueyuan Li ◽  
Yingkun Zhang ◽  
Xiaoqi Wang
Keyword(s):  
Organic Matter ◽  
Pore Size ◽  
Adsorption Capacity ◽  
Thermal Evolution ◽  
Methane Adsorption ◽  
Storage Site ◽  
Pressure Sensitivity ◽  
Adsorption Characteristics ◽  
Shale Reservoirs ◽  
Organic Pores

AbstractIn shale reservoirs, the organic pores with various structures formed during the thermal evolution of organic matter are the main storage site for adsorbed methane. However, in the process of thermal evolution, the adsorption characteristics of methane in multi type and multi-scale organic matter pores have not been sufficiently studied. In this study, the molecular simulation method was used to study the adsorption characteristics of methane based on the geological conditions of Longmaxi Formation shale reservoir in Sichuan Basin, China. The results show that the characteristics of pore structure will affect the methane adsorption characteristics. The adsorption capacity of slit-pores for methane is much higher than that of cylindrical pores. The groove space inside the pore will change the density distribution of methane molecules in the pore, greatly improve the adsorption capacity of the pore, and increase the pressure sensitivity of the adsorption process. Although the variation of methane adsorption characteristics of different shapes is not consistent with pore size, all pores have the strongest methane adsorption capacity when the pore size is about 2 nm. In addition, the changes of temperature and pressure during the thermal evolution are also important factors to control the methane adsorption characteristics. The pore adsorption capacity first increases and then decreases with the increase of pressure, and increases with the increase of temperature. In the early stage of thermal evolution, pore adsorption capacity is strong and pressure sensitivity is weak; while in the late stage, it is on the contrary.

scholarly journals Adsorption Characteristics and Controlling Factors of CH4 on Coal-Measure Shale, Hedong Coalfield

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 63
Author(s):  
Weidong Xie ◽  
Meng Wang ◽  
Hongyue Duan
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Mineral Composition ◽  
Shale Gas ◽  
Total Content ◽  
Coal Measure ◽  
Gas Reservoirs ◽  
Quartz Content ◽  
Adsorption Characteristics ◽  
Adsorbed Gas

Adsorbed gas is one of the crucial occurrences in shale gas reservoirs; thus, it is of great significance to ascertain the adsorption capacity of shale and the adsorption characteristics of CH4. In this investigation, the Taiyuan–Shanxi Formations’ coal-measure shale gas reservoir of the Carboniferous–Permian era in the Hedong Coalfield was treated as the research target. Our results exhibit that the shale samples were characterized by a high total organic carbon (TOC) and over to high-over maturity, with an average TOC of 2.45% and average Ro of 2.59%. The mineral composition was dominated by clay (62% on average) and quartz (22.45% on average), and clay was mainly composed of kaolinite and illite. The Langmuir model showed a perfect fitting degree to the experimental data: VL was in the range of 0.01 cm3/g to 0.77 cm3/g and PL was in the range of 0.23–8.58 MPa. In addition, the fitting degree depicted a linear negative correlation versus TOC, while mineral composition did not exhibit a significant effect on the fitting degree, which was caused by the complex pore structure of organic matter, and the applicability of the monolayer adsorption theory was lower than that of CH4 adsorption on the mineral’s pore surface. An apparent linear positive correlation of VL versus the TOC value was recorded; furthermore, the normalized VL increased with the growth of the total content of clay mineral (TCCM), decreased with the growth of the total content of brittle mineral (TCBM), while there was no obvious correlation of normalized VL versus kaolinite, illite and quartz content. The huge amount of micropores and complex internal structure led to organic matter possessing a strong adsorption capacity for CH4, and clay minerals also promoted adsorption due to the development of interlayer pores and intergranular pores.

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