| Abstract
| - We propose a new algorithm based on application of cluster analysis to group adsorbate molecules of ahighly dense adsorbed phase in the atomistic structural model of a disordered material into connected anddisconnected clusters, through which pore network connectivity of the material is identified. Our proposedalgorithm is then validated using a synthetic pore structure, as well as the reconstructed structure of a saccharosechar obtained in our recent work using hybrid reverse Monte Carlo simulation. The algorithm also identifieskinetically closed pores in the latter structural model that are not accessed by adsorbate molecules at lowtemperature, at which their kinetic energy cannot overcome potential barriers at the mouths of pores that canotherwise accommodate them. The results are validated by transition state theory calculations for N2 and Aradsorption, showing that N2 can equilibrate in narrow micropores at practical time scales at 300 K, but notat 77 K. Large differences between time scales for micropore entry and exit are predicted at low temperaturefor N2, the latter being larger by over 3 orders of magnitude, suggesting hysteresis. Similar behavior is predictedfor Ar in the same char at 87 K. The results explain several long standing issues such as the observed increaseof adsorption of nitrogen with an increase in temperature in coals, hysteresis phenomena in microporouscarbons, and underprediction of adsorption of supercritical gases using structural parameters extracted fromsubcritical adsorption of nitrogen.5 Finally, the determination of pore accessibility and connectivity in disorderedporous carbons using our proposed model enables one to obtain correct adsorbed quantities as well as self-diffusivities and transport diffusivities using conventional grand canonical Monte Carlo and molecular dynamicssimulations.
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