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Vacancy solution theory for binary adsorption equilibria in heterogeneous carbon
Author(s) -
Ding L. P.,
Bhatia S. K.
Publication year - 2002
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690480911
Subject(s) - adsorption , vacancy defect , microporous material , thermodynamics , activated carbon , chemistry , carbon fibers , binary number , materials science , organic chemistry , mathematics , crystallography , physics , arithmetic , composite number , composite material
A heterogeneous modified vacancy solution model of adsorption developed is evaluated. The new model considers the adsorption process through a mass‐action law and is thermodynamically consistent, while maintaining the simplicity in calculation of multicomponent adsorption equilibria, as in the original vacancy solution theory. It incorporates the adsorbent heterogeneity through a pore‐width‐related potential energy, represented by Steele's 10–4–3 potential expression. The experimental data of various hydrocarbons, CO 2 and SO 2 on four different activated carbons—Ajax, Norit, Nuxit, and BPL—at multiple temperatures over a wide range of pressures were studied by the heterogeneous modified VST model to obtain the isotherm parameters and micropore‐size distribution of carbons. The model successfully correlates the single‐component adsorption equilibrium data for all compounds studied on various carbons. The fitting results for the vacancy occupancy parameter are consistent with the pressure change on different carbons, and the effect of pore heterogeneity is important in adsorption at elevated pressure. It predicts binary adsorption equilibria better than the IAST scheme, reflecting the significance of molecular size nonideality.