Adsorption of pure carbon dioxide and methane on dry coal from the Sulcis Coal Province (SW Sardinia, Italy)

Enhanced coalbed methane recovery (ECBM) increases the recovery of the methane present in a coal seam by injecting CO2 at high pressure. It is attractive from two perspectives, the valuable methane recovered and the storage of the greenhouse gas CO2 for geological times. In the framework of a feasibility study for the Sulcis Coal Province in Italy, the adsorption of pure CO2 and CH4 on dry coal has been measured at 45 and 60 degrees C, using a magnetic suspension balance with in situ density measurement. The results show that the CO2 adsorption isotherms on coal are similar to those for other standard adsorbents such as silica gel and activated carbon. From the excess adsorption isotherms, the absolute adsorption is calculated using the assumption of constant volume of the adsorbed phase. As expected, CO2 get adsorbed more than CH4 in all cases. ne Sulcis coal can uptake CO2 at the reservoir conditions in an amount of about 10% of its mass. (c) 2006 American Institute of Chemical Engineers Environ Prog, 25: 355-364, 2006.