Mechanistic Mass-Transfer Modeling for the Adsorption of Water Vapor By Molecular Sieves

Accurate modeling of adsorption kinetics is key to reactor design for engineered separation processes. Simple empirical models, such as the shrinking core or linear driving force model, are often adopted to describe adsorption kinetics for these processes. However, use of these empirical models introduces error to the macroscopic transport models for the overall system and can utterly fail to describe desorption. Additionally, these simple models occasionally involve many parameters that may vary with temperature, pressure, or other factors. These problems emphasize the need for a more fundamental way of modeling adsorption mass transfer processes at the microscopic level. Here, we will present an easy-to-use mass and energy transfer modeling framework. This framework is built using a high-resolution, conservative finite difference scheme and comes with built-in linear and non-linear solvers for extended flexibility. We will discuss briefly how this framework operates and then demonstrate the capabilities with real world problems. Our focus will be on accurate modeling of the mass-transfer mechanisms that govern the adsorption and desorption of water vapor in commercial adsorbents. This particular work will be applied to the separation and recovery of radioisotopic gases, such as tritium vapor (HTO), produced through the reprocessing of used nuclear fuel.