Simultaneous Estimation of Gas Adsorption Equilibria and Kinetics of Individual Shaped Adsorbents

Abstract

Shaped adsorbents (e.g., pellets, extrudates) are typically employed in several gas separation and sensing applications. The performance of these adsorbents is dictated by two key factors, their adsorption equilibrium capacity and kinetics. Often, adsorption equilibrium and textural properties are reported for materials. Adsorption kinetics are seldom presented due to the challenges associated with measuring them. The overarching goal of this work is to develop an approach to characterize the adsorption properties of individual shaped adsorbents with less than 100 mg of material. To this aim, we have developed an experimental dynamic sorption setup and complemented it with mathematical models, to describe the mass transport in the system. We embed these models into a derivative-free optimizer to predict model parameters for adsorption equilibrium and kinetics. We evaluate and independently validate the performance of our approach on three adsorbents that exhibit differences in their chemistry, synthesis, formulation, and textural properties. Further, we test the robustness of our mathematical framework using a digital twin. We show that the framework can rapidly (i.e., in a few hours) and quantitatively characterize adsorption properties at a milligram scale, making it suitable for the screening of novel porous materials.

Measurement of Physicochemical Properties and CO2, N2, Ar, O2, and H2O Unary Adsorption Isotherms of Purolite A110 and Lewatit VP OC 1065 for Application in Direct Air Capture

“…Temperature-dependent Toth (td-Toth), chemi-physisorption (CP), and virial isotherm model fits for the CO 2 adsorption data, single-site Langmuir (SSL) isotherm model fits for the N 2 data, and Guggenheim−Anderson−de Boer (GAB) isotherm model fits for the H 2 O adsorption data were performed using the procedure described in our previous works. 42,43 This procedure was carried out with MATLAB R2020a (The Mathworks Inc.) using the in-house software package isothermFittingTool. 44 The isosteric heats of adsorption for CO 2 , N 2 , and H 2 O were calculated by using the van't Hoff equation for specified loading (n) and corresponding pressure (P) values.…”

Marrying Materials and Processes: A Unified Optimization for Adsorption Processes

“…Second, we assume the mass transfer between the solid and the gas phases to be defined by the linear driving force model and existing only in the macropores of the functionalized adsorbent. We acknowledge that not all the materials have the same kinetic behavior and it is a laborious task to accurately characterize the kinetic behavior for a large number of materials typically reported in material screening studies. , However, to facilitate the achievement of the primary goal of this study, i.e., to propose and validate an integrated material–process screening approach, we assume the mass transfer among all the materials to be macropore controlled. Third, we use Darcy’s law to describe the pressure drop in the column along its axial direction.…”

Marrying Materials and Processes: A Unified Optimization for Adsorption Processes

“…Second, we assume the mass transfer between the solid and the gas phase to be defined by the linear driving force model and existing only in the macropores of the functionalized adsorbent. We acknowledge that not all the materials have the same kinetic behaviour and it is a laborious task to accurately characterize the kinetic behaviour for a large number of materials typically reported in material screening studies [49,50].…”