The Effects of CO2 Interaction with Coal
Favors, Ryan N. 1,2, and Goodman, Angela L. 3
1National Energy Technology Laboratory, U.S. Department of Energy, Pittsburgh, PA 15236
2Purdue University, Chemistry Department, West Lafayette, IN 47907
3National Energy Technology Laboratory, U.S Department of Energy, Pittsburgh, PA 15236
An important option for long-term storage of carbon dioxide (CO2), a greenhouse gas, is to capture it from power plant flue gas and sequester it in coal seams. Here, we report the nature and relative significance of CO2 interactions with coal, based on attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Experiments were carried out at temperatures ranging from 328 K to 383 K (55ºC to 110ºC) and CO2 pressures ranging from 0.35 MPa to 14 MPa. Data was obtained by observing the sorbed CO2 band on Argonne Premium coal samples around 2330 cm-1. Kinetic studies reveal that with repeated exposures, subsequent CO2-coal sorption is much faster than the initial uptake and the amount of CO2 sorbed increases, indicating that exposure of coals to CO2 under these conditions results in changes in the physical structure of the coal. The energy of adsorption for the Argonne Premium coal samples was estimated to be ~20-25 kJ/mol, using the Van’t Hoff equation. These values are consistent with physisorption and compares well with the literature values reported. In addition to kinetic studies, high pressure CO2 adsorption isotherms have been measured using ATR-FTIR. Adsorption isotherms are important to measure the CO2 storage capacity in coal seams.