Boosting CO2 separation from flue gas through two-dimensional interface engineering of MOFs promoters via hydrate-based method

Hydrate-based technology offers an environmentally friendly and energy-efficient route for CO 2 capture from flue gas, but its practical application is hindered by slow kinetics, high compression energy demand and limited separation efficiency. To address these challenges, this study introduces three-dimensional (3D) nanoporous metal-organic frameworks (MOFs) as kinetic promoters for enhanced CO 2 capture from the simulated flue gas (20% CO 2 /80% N 2 ). Particularly, we functionalize 3D MIL-100(Fe) with 2D boron nitride oxide (BNO) to construct a BNO/MIL-100(Fe) 2D/3D hybrid architecture featuring substantially enhanced specific surface area and optimized pore characteristics. Compared to unmodified MIL-100(Fe), 2D Ni/Fe layered double hydroxide (Ni/Fe-LDH), graphitic carbon nitride (g-C 3 N 4 ) and one-dimensional (1D) multi-walled carbon nanotubes (MWCNTs), the BNO/MIL-100(Fe) hybrid exhibits superior kinetic promotion performance, owing to the specific surface area as high as 1001.81 m 2 /g and tailored porosity that facilitate efficient CO 2 mass transfer and provide abundant nucleation sites, thereby accelerating hydrate formation. Consequently, the induction time is shortened by approximately 51% compared with pure tetrahydrofuran in the control group and the overall CO 2 hydrate growth is significantly accelerated. Under a low operating pressure of 2.5 MPa and at 275 K, BNO/MIL-100(Fe) achieves a CO 2 storage capacity of 3.99 mmol CO 2 /mol H 2 O and a high separation efficiency of 82.57%, substantially outperforming most reported hydrate-based promoters. This work highlights the strong potential of MOF-based kinetic promoters and provides new insights into the design of advanced materials that integrate 2D modifiers with 3D nanoporous frameworks for efficient CO 2 separation.