Understanding the CO2 adsorption hysteresis under low pressure: An example from the Antrim Shale in the Michigan Basin: Preliminary observations

The NaCaA-85 zeolite sample which works as an efficient adsorbent for CO2 at RT and in low pressure range was found and its specificity is nicely explained by the model composed of CO2 pinned by two types of Ca2+ ions through far-IR and DFT studies.

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Supercritical CO2 Exposure-Induced Surface Property, Pore Structure, and Adsorption Capacity Alterations in Various Rank Coals

Energies ◽

10.3390/en12173294 ◽

2019 ◽

Vol 12 (17) ◽

pp. 3294 ◽

Cited By ~ 2

Author(s):

Zhenjian Liu ◽

Zhenyu Zhang ◽

Xiaoqian Liu ◽

Tengfei Wu ◽

Xidong Du

Keyword(s):

Coal Seam ◽

Pore Structure ◽

Adsorption Capacity ◽

Surface Property ◽

Supercritical Co2 ◽

Co2 Adsorption ◽

Low Pressure ◽

Coal Seam Gas ◽

Adsorption Sites ◽

Co2 Adsorption Capacity

Carbon dioxide (CO2) has been used to replace coal seam gas for recovery enhancement and carbon sequestration. To better understand the alternations of coal seam in response to CO2 sequestration, the properties of four different coals before and after supercritical CO2 (ScCO2) exposure at 40 °C and 16 MPa were analyzed with Fourier Transform infrared spectroscopy (FTIR), low-pressure nitrogen, and CO2 adsorption methods. Further, high-pressure CO2 adsorption isotherms were performed at 40 °C using a gravimetric method. The results indicate that the density of functional groups and mineral matters on coal surface decreased after ScCO2 exposure, especially for low-rank coal. With ScCO2 exposure, only minimal changes in pore shape were observed for various rank coals. However, the micropore specific surface area (SSA) and pore volume increased while the values for mesopore decreased as determined by low-pressure N2 and CO2 adsorption. The combined effects of surface property and pore structure alterations lead to a higher CO2 adsorption capacity at lower pressures but lower CO2 adsorption capacity at higher pressures. Langmuir model fitting shows a decreasing trend in monolayer capacity after ScCO2 exposure, indicating an elimination of the adsorption sites. The results provide new insights for the long-term safety for the evaluation of CO2-enhanced coal seam gas recovery.

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Pressureless and Low-Pressure Synthesis of Microporous Carbon Spheres Applied to CO2 Adsorption

Molecules ◽

10.3390/molecules25225328 ◽

2020 ◽

Vol 25 (22) ◽

pp. 5328

Author(s):

Iwona Pełech ◽

Daniel Sibera ◽

Piotr Staciwa ◽

Urszula Narkiewicz ◽

Robert Cormia

Keyword(s):

Co2 Adsorption ◽

Applied Pressure ◽

Low Pressure ◽

Spherical Particles ◽

Co2 Uptake ◽

Pressure Treatment ◽

Carbon Spheres ◽

Potassium Oxalate ◽

Uniform Size ◽

Pressure Synthesis

In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C.

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Adsorption Hysteresis in Open Slit-like Micropores

Molecules ◽

10.3390/molecules26165074 ◽

2021 ◽

Vol 26 (16) ◽

pp. 5074

Author(s):

Grygorii Dragan ◽

Volodymyr Kutarov ◽

Eva Schieferstein ◽

Alexander Iorgov

Keyword(s):

Fractal Dimension ◽

Adsorption Process ◽

Phase State ◽

Low Pressure ◽

Irreversible Processes ◽

Desorption Process ◽

Adsorption Of Water ◽

Adsorption Hysteresis ◽

Storage Technologies ◽

Open Slit

Adsorption hysteresis in the low-pressure range is only rarely described in the literature. To optimise, for example, heat storage technologies, a deeper understanding of the low-pressure hysteresis (LPH) process is necessary. Here, two thermodynamically based approaches are further developed for analysing the LPH within the framework of thermodynamically irreversible processes and fractal geometry. With both methods developed, it is possible to obtain the description of the adsorption and desorption branches with high accuracy. Within the framework of the two thermodynamic models of the hysteresis loop, generalised equations are obtained with the control parameter in the form of the degree of irreversibility. This is done by taking the adsorption of water on alumina as an example. It is shown that the fractal dimension of the adsorption process is larger than the fractal dimension of the desorption branch, meaning that the phase state of the adsorbate is more symmetric during the adsorption step than in the desorption process.

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