Analysis of multicomponent adsorption kinetics on activated carbon

• Published in: AIChE journal Vol. 49; no. 4; pp. 883 - 895
• Main Authors: Ding, L. P., Bhatia, S. K.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.04.2003; Wiley Subscription Services; American Institute of Chemical Engineers
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-gas interface; Surface physical chemistry; Gas mixture; Hydrocarbon; Multicomponent mixture; Organic adsorbate; Coadsorption; Adsorption isotherm; Theoretical study; Inorganic adsorbent; Experimental study; Modeling; Ethane; Mass transfer; Gas solid adsorption; Activated carbon; Gas solid desorption; Gas solid interface; Kinetics; Mathematical model; Propane
• ISSN: 0001-1541; 1547-5905
• DOI: 10.1002/aic.690490408

An integrated mathematical model for the kinetics of multicomponent adsorption on microporous carbon was developed. Transport in this bidisperse solid is represented by balance equations in the macropore and micropore phases, in which gas‐phase diffusion dominates the mass transfer in the macropores, with the phenomenological diffusivities represented by the generalized Maxwell–Stefan (GMS) formulation. Viscous flow also contributes to the macropore fluxes and is included in the MS expressions. Diffusion of the adsorbed phase controls the mass transfer in the micropore phase, which is also described in a similar way by the MS method. The adsorption isotherms are represented by a new heterogeneous modified vacancy solution theory formulation of adsorption, which has proved to be a robust method for adsorption on activated carbons. The model is applied to the coadsorption and codesorption of C2H6 and C3H8 on Ajax and Norit carbon, as well as the displacement on Ajax carbon. The effect of the viscous flow in the macropore phase is not significant for the cases studied. The model accurately predicts the overshoot behavior and rollup of C2H6 during coadsorption. The prediction for the heavier compound C3H8 is always satisfactory, though at higher C3H8 mole fraction, the overshoot extent of C2H6 is overpredicted, possibly due to neglect of heat effects.