In-Situ Penetrant Transport in Thin Coal Sections

Olivares, J. M.; Peppas, Nicholas A.

doi:10.1080/00986449508936298

Cited by 4 publications

(2 citation statements)

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“…There is also the inevitable mixture of the two diffusion mechanisms called anomalous diffusion. All three diffusion mechanisms, Fickian, case II, and anomalous diffusion have been observed as organic molecules diffuse into coals, swelling them. − …”

Section: Introductionmentioning

confidence: 99%

“…All three diffusion mechanisms, Fickian, case II, and anomalous diffusion have been observed as organic molecules diffuse into coals, swelling them. [11][12][13] Coals are glassy solids, and the temperature at which they become rubbery (T g ) lies above their decomposition temperature. [15][16][17] When swollen by a dissolved molecule, T g decreases, coal properties change, and the coal may undergo a structural rearrangement.…”

Section: Introductionmentioning

confidence: 99%

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Argonne Coal Structure Rearrangement Caused by Sorption of CO₂

2006

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The exposure of powdered unconfined coals to CO 2 results in changes in the coals' physical structures. The presence of water changes the behavior of the coals on exposure to CO 2 . The sorption of CO 2 on seven Argonne premium coals was measured by using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy as a function of time at constant CO 2 pressure (∼0.62 MPa) and temperature (55 °C). The depth sampled is at least 1 µm, and this ensures that both the bulk and surface of the sample were interrogated. Concentrations of CO 2 in the top 1-7 µm of the coal were measured by using the peak area of the CO 2 ATR-FTIR band near 2333 cm -1 . Diffusion rates were measured by using the time dependence of the area of the 2333 cm -1 band. Surface adsorption is effectively instantaneous. The coals were either extensiVely or briefly dried. The coals were exposed to CO 2 , evacuated, and then exposed to CO 2 a second time. For the extensively dried coals, removal of the CO 2 under vacuum was much faster than CO 2 sorption, indicating a coal structure change caused by CO 2 sorption. The diffusion rate of the CO 2 into the coal was much faster for the second exposure, confirming that the coal underwent a physical structure rearrangement. Structure rearrangement was observed for all seven extensively dried coals and for the Pittsburgh No. 8 briefly dried coal. The presence of residual moisture in the briefly dried coal samples appeared to inhibit or block CO 2 uptake as equilibrium was reached within minutes. The second exposure of the briefly dried coals universally resulted in greater CO 2 uptake that was again instantaneous on our experimental time scale.

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Section: Introductionmentioning

confidence: 99%