Spatiotemporal Modeling and Parametric Estimation of Isothermal CO₂ Adsorption Columns

This paper focuses on the development of a rigorous model for isothermal CO₂ adsorption columns which describes the spatiotemporal dynamics of CO₂ concentrations in the bulk and solid bed by a set of partial and location-varying ordinary differential equations. By considering both dispersion and convection phenomena, the model provides the spatiotemporal behavior of the adsorption rate and circumvents the unphysical simplifying assumptions of linear driving force and uniform adsorption rates through the column length invoked in previous modeling efforts. The proposed model is then employed to compute physical quantities originating from material conservation laws such as the adsorption rate constant and CO₂ adsorption capacity from a set of experimental data without using empirical parameter assumptions invoked in previous research. The spatiotemporal dynamics of CO₂ adsorption in an aminosilica packed bed are successfully predicted by the proposed model. The adsorption rate constant and capacity of the bed are then identified using a set of experimental CO₂ concentration measurements at the adsorption column outlet by solving a dynamic optimization problem using a shooting method formulation. Finally, the adsorption enthalpy is computed by employing the heat of adsorption data to validate the estimated parameters of the system.