Effects of Coal Interaction with Supercritical CO₂: Physical Structure

Abstract

It is known that polar solvents swell coal, break hydrogen-bonds in the macromolecular structure, and enhance coal liquefaction efficiencies. The effects of drying, interaction with supercritical CO2 and degassing on the physical structure of coal have been studied using gas sorption technique and a scanning electron microscope (SEM). Both drying and interaction with supercritical CO2 drastically change the micropore and mesopore surface area, absolute volume, and volume distribution in both bituminous coal and lignite. Degassing removes debris in the pore space which allows for better analysis of the changes in the morphology that were induced by drying and exposure to supercritical CO2. SEM reveals that interaction of bituminous coal with supercritical CO2 results in an abundance of carbon structures similar to the maceral collinite.

Influence of CO2 Exposure on High-Pressure Methane and CO2 Adsorption on Various Rank Coals: Implications for CO2 Sequestration in Coal Seams

“…This conclusion is consistent with other investigations. Applying both adsorption and scanning electron microscopy (SEM) methods, Gathitu et al 58 found that CO 2 exposure cannot significantly change the micropore surface and volume of dry bituminous coal. Kutchko et al 59 also concluded that CO 2 exposure made no obvious change to the pore structure of Pittsburgh and Sewickly coal samples, according to fieldemission scanning electron microscopy (FE-SEM) analysis.…”

Migration of metamorphic CO2 into a coal seam: a natural analog study to assess the long‐term fate of CO2 in Coal Bed Carbon Capture, Utilization, and Storage Projects

“…Coal has a strong affinity for CO 2 , and interactions with supercritical CO 2 can drastically change the micropore and mesopore surface area, absolute volume, and volume distribution in both bituminous coal and lignite. After interaction with supercritical CO 2 , micropore surface area and volume is observed to grow (Gathitu et al 2009), but mesopore and macropore surface area and volume increase drastically (Liu et al 2010). In the Yaojie coalfield, supercritical CO 2 is likely to exist in the NO.…”

“…After interaction with supercritical CO 2 , micropore surface area and volume is observed to grow (Gathitu et al . ), but mesopore and macropore surface area and volume increase drastically (Liu et al . ).…”

Changes in Pore Structure of Coal Associated with Sc-CO2 Extraction during CO2-ECBM

“…During the process of CO 2 -ECBM, CO 2 is distributed into the coal seam through the coal cleat system and then stored within the coal matrix due to the stronger affinity between CO 2 and the coal substance [9][10][11]. Previous studies have also shown that there are various physical and geochemical interactions between CO 2 and coals, such as gas adsorption on the coal 2 of 11 internal surface [9][10][11][12][13][14], coal matrix swelling due to gas adsorption [15][16][17], and CO 2 reaction with minerals [18][19][20].…”