Applicability of Adsorbents in Direct Air Capture (DAC): Recent Progress and Future Perspectives

Carbon capture, utilization, and storage (CCUS) has been considered as an approach to mitigate CO2 emissions to achieve a net-zero target as indicated in the Paris Climate Agreement. Nevertheless, over 50% of global CO2 emissions stem from distributed sources; the incorporation of negative emission technologies (NETs) is required. Direct air capture (DAC) is recognized as one of the feasible NETs offering flexibility in installation location. This review primarily focuses on the utilization of solid sorbents, which demonstrate lower energy consumption and higher CO2/N2 selectivity compared to alternative methods (cryogenic distillation and amine scrubbing). It provides a comprehensive analysis of the performance of nonporous and nanoporous adsorbents relevant to DAC applications. Among these, amine-appended adsorbents are the key for the DAC process due to the strong affinity between CO2 and amine at low partial pressure, as highlighted in the literature. Last but not least, the future direction and the practical feasibility of the sorbent-based DAC process will be discussed to allow more effective analysis of adsorbent performance, especially in the context of the repetitive adsorption/desorption cycling process.