High-Pressure Separation of CH4/CO2 Using Activated Carbon

Authors: Carlos A. Grande, Richard Blom, Andreas Möller, Jens Möllmer
Journal: Chemical Engineering Science 89 (2013) 10–20, DOI:10.1016/j.ces.2012.11.024

Abstract:
Activated carbon was evaluated as selective adsorbent for separation of CO₂ from CO₂/CH₄ mixtures with special focus on high pressure applications. Binary adsorption equilibrium measurements and binary breakthrough curves with mixtures of 10 and 20% CO₂ balanced with CH₄ were carried out at three different pressures: 500, 2500 and 5000 kPa. A 1D mathematical model including mass, energy and momentum transport was used to describe the curves using a non-ideal gas behavior equation. CO₂ is more selectively adsorbed than CH₄ in the activated carbon used in this study. The binary adsorption capacity obtained from binary breakthrough curves could only be well described by the Sips model. In all breakthrough curves, a small effect of the film mass transfer could be observed, particularly at higher pressures where this effect is more pronounced. The significant adsorption of CH₄ may limit the application of this adsorbent for natural gas upgrading.