(162b) NET Adsorption for Multicomponent GAS Equilibrium

The net adsorption thermodynamic framework was recently introduced as an alternative to excess and absolute adsorption (Gumma and Talu, Langmuir 2010, 26(22), 17013-17023).  It is a fundamentally different thermodynamic description of adsorption since the placement of Gibbs dividing surface, necessary for any treatment of adsorption, is different than the known/used alternatives.  Net adsorption is a natural choice for microporous solids.  It removes any ambiguity in theory and simulations of adsorption and circumvents all questionable measurements/quantities in experiments.

     Initial development of net adsorption was prompted by the interest in adsorptive gas storage and by the need to unambiguously compare experiments to molecular simulation results.  Previously, our research group and others have shown that: 1) non-adsorbing helium assumption commonly used to place the Gibbs dividing surface in experiments does not hold (e.g. Gumma and Talu, Adsorption J. 2003, 9, 17-28), and 2) molecular simulation results can only be compared to excess data by performing more simulations with helium (e.g. Talu and Myers, AIChE J. 2001, 47(5), 1160-1168).  As such, previous work has concentrated on pure component adsorption equilibrium and dynamics with net adsorption.

     This contribution involves extension of net adsorption framework to gas mixtures.  Equilibrium formulations will be presented, net and excess adsorption will be compared with a set of experimental data, and implications of net framework on column dynamics for adsorption processes will be discussed.