Pore-Regulation strategy of AlFum mediated by polyethyleneimine for CO2 capture

Polymer-mediated strategy enables AlFum with regulated pore structure. • Microporous domains are enhanced while the AlFum framework remains intact. • The optimized AlFum achieves a 25.5% higher CO 2 uptake at 0.15 bar. • Sorption heat of the materials remains far below typical amine-loaded sorbents. The compact crystallization and dense particle aggregation of aluminium fumarate (AlFum) may limit the effective utilization of its intrinsic microporous sorption domains for CO 2 capture. To address these limitations, a pore-structure regulation strategy is developed by employing polyethyleneimine as a transient polymeric modulator during the synthesis of AlFum. Unlike conventional amine-loading strategies that enhance CO 2 affinity through retained amine-rich phases but may sacrifice microporosity and increase sorption energetics, this approach is associated with dosage-dependent changes in particle assembly and textural pore development while preserving the intrinsic AlFum framework. The optimized AlFum(PEI-0.2) delivers the best CO 2 sorption performance among the series, with a 25.5% uptake enhancement at 0.15 bar. Despite the improved capacity, it maintains a moderate isosteric heat of 21–25 kJ mol −1 , consistent with predominantly physisorption-based and reversible CO 2 sorption. Delayed CO 2 breakthrough and increased dynamic CO 2 uptake under 15% CO 2 /85% N 2 demonstrate enhanced dynamic CO 2 retention for AlFum(PEI-0.2), while five consecutive breakthrough cycles at 30% RH retain 96.6% of the first-cycle uptake. GCMC simulations further identify the intrinsic micropores of ideal AlFum as preferential equilibrium CO 2 sorption domains. This strategy establishes a pore-structure design enabled by transient polymeric modulation, balancing intrinsic microporous domains with textural pore development and providing a promising route toward stable Al-based MOF adsorbents for CO 2 capture. Download: Download high-res image (213KB) Download: Download full-size image