Lewatit 1065 VP OC for direct air capture; an analysis of adsorption characteristics using dynamic column breakthrough

Direct air capture based on solid sorbents (S-DAC) is increasingly being recognized as an essential part of climate change mitigation strategies. This work investigates the adsorption characteristics for Lewatit 1065 OC VP which is considered a benchmark sorbent for S-DAC processes. A novel dynamic column breakthrough (DCB) instrument suited for DAC compositions is developed and described. Using both DCB experiments and volumetric measurements, we have identified a significant intra-batch variability in the CO 2 loading capacity. The observed difference in CO 2 capacity is found to depend entirely on the particle size from the manufacturer; thus, highlighting the importance of standardized sample selections when evaluating the properties of amine-functionalized materials. This ensures a solid database for process modeling and avoids misleading performance results of S-DAC processes. The mass transfer kinetics has been evaluated from both adsorption and desorption breakthrough experiments combined with modeling. The modeling effort includes a comparison between the commonly used linear driving force (LDF) model and a dual-site (DS) model to describe the CO 2 uptake. A significant dependence on macropore resistance is confirmed, though an additional transport resistance is required to fully describe the mass transfer kinetics. We hypothesize that the CO 2 -amine reaction is the key contributor to the added mass transfer resistance prompting the research on new amine-functionalized materials to focus on enhancing both the macropore resistance and reaction kinetics. • Novel instrument for dynamic column breakthrough at direct air capture compositions. • Intra-batch variability in CO 2 loading is confirmed for Lewatit 1065 VP OC. • Mass transfer kinetics depends on macropore resistance and reaction kinetics. • Dual-site model can describe adsorption and desorption rates.