Recent advances in potassium-based adsorbents for CO2 capture and separation: a review

Anthropogenic CO2 emissions from fossil fuel combustion and industrial processes are considered as the major contributors to global warming and climate change. Deploying carbon capture, storage and utilization (CCUS) has been perceived as one important strategy to mitigate CO2 emission and to realize carbon neutrality. Dry potassium-based adsorbents with desirable attributes show promise for capturing CO2 from flue gas and other ultra-dilute gas stream. The past decade has witnessed rapid development in dry potassium-based CO2 adsorbents. This review summarizes the recent progress of potassium-based adsorbents in CO2 capture. A detailed and in-depth discussion concerning the carbonation pathways is presented. Strategies for carbonation enhancement are demonstrated from the perspective of the rational design of adsorbents and process optimizations. Kinetics modelling of the carbonation and regeneration behaviors of potassium-based adsorbents is then illustrated. Apart from flue gas cleaning, the potential applications of potassium-based adsorbents in other fields such as low-concentration CO2 removal from environmental control and life support systems (ECLSSs), direct air capture (DAC), and integrated CO2 capture and utilization (ICCU) have also been discussed. Finally, comments on the main challenges and future opportunities of the dry potassium-based adsorbents are provided.