Co-Adsorption and Pure-Component Isotherm Measurements on Direct Air Capture Adsorbents Using The Dvs Vacuum

Abstract

Temperature vacuum swing adsorption processes that employ amine-functionalised adsorbents are a promising technology to enable carbon dioxide removal directly from the atmosphere. These adsorbents capture carbon dioxide selectively over nitrogen from the air. They also capture significant amounts of water. The co-adsorption of carbon dioxide and water is still poorly understood due to the difficulty of measuring this effect. To date, water adsorption and co-adsorption measurements were time-consuming as breakthrough or equilibrium adsorption experiments were required for each point on an isotherm. Additionally, data required for the accurate modelling of the process includes pure-component water and carbon dioxide isotherms at a range of temperatures and co-adsorption isotherms at a range of temperatures and relative humidities. Attempting to model direct air capture (DAC) processes without this complete set of data might lead to a limited understanding of the process. As a result, process design may be sub-optimal, and the chosen operating conditions might be inefficient. Here we demonstrate how co-adsorption isotherms and purecomponent isotherms can be measured swiftly on an amine-functionalised adsorbent using the Dynamic Vapour Sorption (DVS) Vacuum instrument. We also show how the obtained data can be used to perform first-order kinetic analysis. In this study, Lewatit VP OC 1065® is chosen as an example of an amine-functionalised adsorbent, as it is believed to be similar to the sorbents used by some commercial DAC companies.