(523d) Henry's Law Constants and Isosteric Heats of Adsorption for Multi-Wall Carbon Surfaces with Different Geometries

Henry's law constants and isosteric heats of adsorption are calculated for argon, nitrogen, methane, carbon dioxide, hydrogen, and helium adsorbed on multi-wall carbon surfaces for slit-shaped, cylindrical, and spherical geometries. The Henry's law constant is found to be sensitive to the pore width, surface mean curvature, and number of layers of wall. We examine the importance of multiple layer walls on the heat of adsorption. For argon adsorbed on multi-wall carbon surfaces, over 99% of the total maximum heat of adsorption is from the first seven layers. For slit-shaped carbon surfaces, heats of adsorption obtained from Steele's 10-4-3 potential are also included for comparison. Good agreement is found between our calculated results and experimental and simulation results in the literature. We also develop simple equations that can be used to convert Henry's law constants from an absolute volume basis to an accessible volume basis for single-wall geometries.