Implications of Defect Density and Polymer Interactions for CO2  Capture on Amine-Functionalized MIL-101(Cr)

ChemSusChem. 2024 Apr 16:e202400249. doi: 10.1002/cssc.202400249. Online ahead of print.ABSTRACTRising anthropogenic carbon emissions have dire environmental consequences, necessitating remediative approaches, which includes use of solid sorbents. Here, aminopolymers (poly(ethylenimine) (PEI) and poly(propylenimineimine) (PPI)) are supported within solid mesoporous MIL-101(Cr) to examine effects of support defect density on aminopolymer-MOF interactions for CO2 uptake and stability during uptake-regeneration cycles. Using simulated flue gas (10 % CO2 in He), MIL-101(Cr)-ρhigh (higher defect density) shows 33 % higher uptake capacity per gram adsorbent than MIL-101(Cr)-ρlow (lower defect density) at 308 K, consistent with increased availability of undercoordinated Cr adsorption sites at missing linker defects. Increasing aminopolymer weight loadings (10-50 wt.%) within MIL-101(Cr)-ρlow and MIL-101(Cr)-ρhigh increases amine efficiencies and CO2 uptake capacities relative to bare MOFs, though both incur CO2 diffusion limitations through confined, viscous polymer phases at higher (40-50 wt.%) loadings. Benchmarked against SBA-15, lower polymer packing densities (PPI > PEI), weaker and less abundant van der Waals interactions between aminopolymers and pore walls, and open framework topology increase amine efficiencies. Interactions between amines and Cr defect sites incur amine efficiency losses but grant higher thermal and oxidative stability during uptake-regeneration cyc...
Source: ChemSusChem - Category: Chemistry Authors: Source Type: research