Potential effect of carbon dioxide injection on the functional groups of medium volatile bituminous coals analysed using in-situ diffuse reflectance Fourier-transform infrared spectroscopy

Li, Jianxin; Pan, Jienan; Wang, Xianglong; Wang, Kai; Nie, Songlin; Gao, Di

doi:10.1016/j.coal.2022.104169

Cited by 21 publications

(7 citation statements)

References 74 publications

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“…These findings suggest that changes in confining pressure have a greater impact on the mechanical properties of CO 2 -treated coal samples. Experimental studies have confirmed that CO 2 adsorption in the coal mass reduces its strength by reorganizing the coal structure from an initially strained state to a more relaxed state with lower surface tension [8,15,34]. This weakened coal mass is more vulnerable to changes in the confining pressure environment, resulting in a greater increase in deviatoric stress as confining pressure rises.…”

Section: Modelling Results and Discussionmentioning

confidence: 92%

A Laboratory-Scale Numerical Investigation of the Effect of Confinement Conditions on the Mechanical Responses of Coal under Various Saturation Conditions

Wang,

Ding

et al. 2023

Processes

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Deep coal seams are generally preferred for CO2 sequestration, during which the saturation fluids and high-stress condition involved can significantly alter the mechanical attributes of coal. To understand the effect of stress conditions on the mechanical properties of coal during CO2 sequestration, a finite element model was developed and subsequently validated using experimental data. The results indicate that coal strength increases from 10.35% for a 5 MPa CO2-saturated sample to 114.54% for an 8 MPa CO2 + water-saturated sample as the confining pressure rises from 0 to 30 MPa, due to reduced porosity. However, this effect diminishes with higher confining pressures as dilation decreases. The critical confining pressure determined in this study is approximately 20 MPa, at which all samples exhibit similar failure strength (around 48.50 MPa). Moreover, the strengthening effect caused by applied stress is especially pronounced in CO2-saturated samples, particularly in those saturated with super-critical CO2 and CO2 + water. This suggests that the reduction in coal strength resulting from the adsorption of saturation fluids can be counterbalanced by the strength gain resulting from applied stress. The aforementioned results highlight the effectiveness of injecting high-pressure super-critical CO2 into deep coal seams for carbon sequestration purposes.

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Section: Modelling Results and Discussionmentioning

confidence: 92%

A Laboratory-Scale Numerical Investigation of the Effect of Confinement Conditions on the Mechanical Responses of Coal under Various Saturation Conditions

Wang,

Ding

et al. 2023

Processes

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“…An in-depth study of the mechanism of carbon dioxide softening coal is helpful to promote the clean and efficient use of coal resources, promote sustainable energy development, and reduce the adverse impact on the environment and climate. After injecting CO 2 into coal, the coal undergoes both physical and chemical transformations . The following will provide a detailed elaboration and discussion.…”

Section: Resultsmentioning

confidence: 99%

“…After injecting CO 2 into coal, the coal undergoes both physical and chemical transformations. 38 The following will provide a detailed elaboration and discussion.…”

Section: Resultsmentioning

confidence: 99%

Effect of CO₂–H₂O Interaction with High-Rank Coal on Mechanical Properties and Acoustic Emission Characteristics under Confining Pressure

Yi,

Pan,

Wang

et al. 2024

ACS Omega

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The adsorption of CO2 by coal leads to changes in its mechanical properties, particularly when considering supercritical CO2 and water with supercritical CO2 adsorption. This is strongly linked to the efficiency of CO2-enhanced coalbed methane (CO2-ECBM) extraction and the safety of CO2 geological storage. This study focuses on 3# coal from the Datong Mine in Gaoping City, Shanxi Province. The high-rank coal’s mechanical properties, including the triaxial compressive strength and elastic modulus, were examined under the combined effects of CO2 injection pressure, CO2 injection time, and moisture content. The triaxial compressive strength and elastic modulus of the coal showed a decrease following CO2 injection. Increasing the CO2 injection pressure, prolonging the CO2 injection time, and increasing the moisture content were favorable for coal softening. In particular, the triaxial compressive strength and elastic modulus of the coal sample after 144 h of water and supercritical CO2 softening decreased by 67.67 and 64.15%, respectively. Injecting CO2 into coal changed its failure mode. The dry raw coal sample exhibited a brittle shear failure mode, while the coal samples showed transitional shear failure after injecting 6 MPa CO2 and 8 MPa CO2 and ductile nondilatant barreling failure after injecting water and 8 MPa CO2 (with a moisture content of 3.02%). Moreover, the cumulative acoustic emission energy of the coal samples followed a similar trend to the decrease in mechanical properties under different conditions. The physical and chemical interactions among coal, CO2, and water caused the softening of coal; these included the generation of the swelling stress, the dissolution of minerals by carbonate solutions, the reduction in surface energy of coal owing to CO2 adsorption, and the extraction and plasticization reactions of organic matter in coal. The research results are of great significance for further understanding CO2-ECBM and CO2 geological sequestration.

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“…These results are consistent with the FT-IR data. The categories of oxygen-containing functional groups on the surface of activated carbon can exhibit the adsorption selectivity to gas molecules with different polarities. , Although N 2 , CH 4 , and CO 2 are nonpolar molecules, both the C–H bonds in CH 4 and the CO bonds in CO 2 are polar, and the polarizability of CH 4 or CO 2 is greater than that of N 2 . Hence, the oxygen-containing functional groups on the surface of activated carbon are more likely to interact with CH 4 and CO 2 with higher polarizability.…”

Section: Resultsmentioning

confidence: 99%

Adsorption Equilibrium and Diffusion of CH₄, CO₂, and N₂ in Coal-Based Activated Carbon

et al. 2023

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Coal-based activated carbon is an ideal adsorbent for concentrating CH4 from coalbed methane and recovering CO2 from industrial waste gas. In order to upgrade the environmentally protective preparation technology of coal-based activated carbons and clarify the adsorption equilibrium and diffusion rules of CH4, CO2, and N2 in these materials, we prepared granular activated carbon (GAC) via air oxidation, carbonization, and physical activation using anthracite as the raw material. Also, we measured the adsorption isotherms and adsorption kinetic data of GAC by the gravimetric method and characterized its surface chemical properties. According to the results, GAC had abundant micropore structures with a pore size mainly in the range of 5.0–10.0 Å, and its surface was covered with plentiful oxygen-containing functional groups. The specific pore structure and surface chemical properties could effectively improve the separation and purification effects of GAC on CH4 and CO2. In the temperature range of 278–318 K, the equilibrium separation of CH4/N2 by GAC with a coefficient between 3 and 4 could be achieved. Also, the CO2/CH4 separation coefficient decreased with the increase in temperature but remained around 3. The bivariate Langmuir equation could describe the adsorption behaviors of GAC on CH4/N2, CO2/N2, and CH4/CO2. With the increase in the concentrations of CH4 and CO2 in the gas phase, the difference between the adsorption capacity of CH4 or CO2 and that of N2 became greater. The change of the gas ratio did not affect the characteristics of preferential adsorption of CH4 and CO2. At different temperatures (278, 298, and 318 K), the diffusion coefficients of CH4, N2, and CO2 at various pressure points showed predominately a small variation without an obvious trend. These results demonstrated that the separation of CH4/N2, CO2/N2, and CH4/CO2 by the activated carbon could only rely on the equilibrium separation effect rather than the kinetic effect.

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Potential effect of carbon dioxide injection on the functional groups of medium volatile bituminous coals analysed using in-situ diffuse reflectance Fourier-transform infrared spectroscopy

Cited by 21 publications

References 74 publications

A Laboratory-Scale Numerical Investigation of the Effect of Confinement Conditions on the Mechanical Responses of Coal under Various Saturation Conditions

A Laboratory-Scale Numerical Investigation of the Effect of Confinement Conditions on the Mechanical Responses of Coal under Various Saturation Conditions

Effect of CO₂–H₂O Interaction with High-Rank Coal on Mechanical Properties and Acoustic Emission Characteristics under Confining Pressure

Adsorption Equilibrium and Diffusion of CH₄, CO₂, and N₂ in Coal-Based Activated Carbon

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Potential effect of carbon dioxide injection on the functional groups of medium volatile bituminous coals analysed using in-situ diffuse reflectance Fourier-transform infrared spectroscopy

Cited by 21 publications

References 74 publications

A Laboratory-Scale Numerical Investigation of the Effect of Confinement Conditions on the Mechanical Responses of Coal under Various Saturation Conditions

A Laboratory-Scale Numerical Investigation of the Effect of Confinement Conditions on the Mechanical Responses of Coal under Various Saturation Conditions

Effect of CO2–H2O Interaction with High-Rank Coal on Mechanical Properties and Acoustic Emission Characteristics under Confining Pressure

Adsorption Equilibrium and Diffusion of CH4, CO2, and N2 in Coal-Based Activated Carbon

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Effect of CO₂–H₂O Interaction with High-Rank Coal on Mechanical Properties and Acoustic Emission Characteristics under Confining Pressure

Adsorption Equilibrium and Diffusion of CH₄, CO₂, and N₂ in Coal-Based Activated Carbon