What question did this study set out to answer?

The study aims to identify scalable materials for efficient CO2 capture under low concentration and humid conditions.

March 18, 2026Open Access

Scalable metal–organic frameworks for efficient low concentration CO 2 capture under humid flue gas conditions

Key Points

The study aims to identify scalable materials for efficient CO2 capture under low concentration and humid conditions.
Investigation of CALF-20, a scalable metal-organic framework, for CO2 adsorption performance.
Comparison of CO2 capture capabilities under dynamic breakthrough conditions and static isotherm data.
Assessment of hydrophilicity impact on regenerability under realistic flue gas conditions.
CALF-20 achieved a high CO2 uptake of 1.49 mmol g-1 under 2.5% CO2 and 50% relative humidity.
It demonstrated complete regenerability at 80 °C without performance loss over multiple cycles.
Shown to outperform hydrophilic zeolites in terms of performance under humid conditions.

Abstract

The global energy supply still largely relies on fossil fuels, whose combustion releases significant amounts of carbon dioxide (CO2), the primary anthropogenic greenhouse gas linked to climate change. Adsorption on solid porous materials offers a promising alternative to conventional amine-based systems for CO2 capture from industrial flue gases. While various materials, including zeolites and metal-organic frameworks (MOFs), have been extensively studied for high-concentration CO2 streams, post-combustion capture at low concentrations (below 5% CO2) under realistic conditions with water vapor remains poorly explored. Material selection requires balancing CO2 adsorption capacity against water affinity, as strong hydrophilicity deteriorates regeneration efficiency. The challenge is to identify scalable, environmentally friendly materials that maintain high CO2 selectivity under realistic flue gas conditions containing both low CO2 concentrations and significant water vapor. Here, we show that CALF-20, a scalable MOF, exhibits superior CO2 adsorption selectivity and regenerability compared to other tested materials, both in dry and humid conditions. Under dynamic breakthrough conditions using 2.5% CO2 and 50% relative humidity, CALF-20 maintained a high CO2 uptake (1.49 mmol g-1) consistent with static isotherm data, and demonstrated complete regenerability at 80 °C without loss of performance over multiple cycles. These results directly contrast with hydrophilic zeolites, which, despite high raw CO2 capacities, are unsuitable under realistic, humid flue gas. Our results under industrially relevant post-combustion conditions demonstrate that low water affinity combined with moderate CO2 capacity outperforms high-capacity hydrophilic materials. This approach represents an effective pathway for CO2 capture under realistic conditions and provides valuable insights for the development of selective, robust, and scalable CO2 adsorbents. Such developments are expected to contribute significantly to reducing atmospheric CO2 emissions and addressing climate change mitigation targets in the coming years.

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