Date of Award
Open Access Dissertation
James A. Ritter
A new kinetically limited linear driving force (KLLDF) model, in terms of a modified extended Langmuir (EL) isotherm, was developed. This KLLDF model augments the equilibrium driving force in the linear driving force (LDF) model in such a way that the equilibrium loading of each component in the LDF model depends on the actual, kinetically limited, loading of the other components in a gas mixture, not their partial pressures. In contrast, the LDF model assumes the presence of a slower diffusing adsorbate in a gas mixture affects the equilibrium of a faster diffusing adsorbate in a pore structure via its gas phase partial pressure, even if this slower diffusing component has hardly entered the pore structure. This potentially erroneous assumption of the LDF model for severely diffusion-limited separations is corrected with the new KLLDF model. At equilibrium, the KLLDF model reduces to the LDF model, leading to the same EL isotherm predictions. The KLLDF model correlates well with binary gas mixture uptake experimental data in the literature for CO2-CH4 and O2-N2 on Takeda and Bergbau-Forschung carbon molecular sieves and N2-CH4 on titanium silicate Ba-ETS-4.
In addition, simulation results using our in-house Dynamic Adsorption Process Simulator (DAPS) show the KLLDF model provides a better quantitative fit of the experimental breakthrough data than the LDF model for all the experimental breakthrough runs involving ternary CO2-CH4-He and quaternary CO2-CH4-N2-He mixtures. Predictions of cyclic pressure swing adsorption (PSA) separations runs of binary 15 vol.% CO2 in CH4 mixtures further exposed the poor predictive capabilities of the LDF model while the KLLDF model gave excellent predictions of the experimental performance data. Because the new KLLDF model requires just one fitting parameter for each component in the gas mixture, i.e., the mass transfer coefficient just like the LDF model, it should be very useful in an adsorption process simulator.
Adegunju, S. A.(2023). Development and the Use of a New Kinetically Limited Linear Driving Force Model for Diffusion-Based Adsorptive Separations. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/7141
Available for download on Thursday, May 15, 2025