Theory and simulation of mixed gas adsorption in activated carbons

摘要

Amorphous materials are typically characterised using nitrogen adsorption isotherms at 77K to obtain pore size distributions. However higher temperatures and different adsorbates could also be used. We have measured the adsorption isotherm of nitrogen at room temperature and 77K on the typical high surface area amorphous activated carbon AX21. We analyse these isotherms using density functional theory to obtain pore size distributions and explore whether they vary with temperature and compare with results obtained~5 for carbon dioxide and methane. We find, for example, that the pore structures predicted for AX21 at 77K and 293K are quite different. The room temperature pore size distribution showing a unimodal micropore peak not seen at 77K. The room temperature pore size distribution is used to predict the selectivity of AX21 for methane over nitrogen at 293K between 0 and 1 bar.