High-Performance Selective CO₂ Capture on a Stable and Flexible Metal–Organic Framework via Discriminatory Gate-Opening Effect

Abstract

Selective CO 2 capture is of great significance for environmental protection and industrial demand. Here, we report a stable and flexible metal−organic framework (MOF) with excellent water/moisture stability, namely, ZnDatzBdc, that enables high-performance selective CO 2 capture from N 2 and CH 4 via a discriminatory gate-opening effect. ZnDatzBdc shows reversible structural transformation between the open-phase (OP) state and the close-phase (CP) state, owing to the synergistic effect of breakage/re-formation of intraframework hydrogen bonds and the rotation of the phenyl rings. Significantly, ZnDatzBdc exhibits S-shaped isotherms toward CO 2 , resulting in a large CO 2 theoretical working capacity of 94.9 cm 3 /cm 3 under typical pressure vacuum swing adsorption (PVSA) operations, which outperforms other flexible MOFs showing the CO 2 selective gate-opening effect except for the miosture-sensitive ELM-11. In addition, CO 2 uptake of ZnDatzBdc is well maintained upon multiple water/moisture exposure, indicating its excellent stability. Moreover, ZnDatzBdc establishes remarkable CO 2 selectivity with ultrahigh uptake ratios of CO 2 /N 2 (107 at 273 K and 129 at 298 K) and CO 2 /CH 4 (35 at 273 K and 44 at 298 K) at 100 kPa. The in situ gas sorption PXRD experiment verifies that the gate-opening effect takes place in the atmospheric environment of CO 2 but not for N 2 or CH 4 . Molecular simulation suggests the selective gate-opening of CO 2 comes from its strong electrostatic interactions with the amino groups. Furthermore, effective breakthrough performance and easy regeneration are further confirmed. Hence, combined with excellent separation performance and remarkable stability, ZnDatzBdc can serve as a potential industrial adsorbent for selective CO 2 capture.

Optimized Pore Nanospace through the Construction of a Cagelike Metal–Organic Framework for CO2/N2 Separation

“…The increasingly serious greenhouse effect has led to a series of ecosystem environmental issues, such as melting glaciers, extreme weather, etc., due to past emissions of CO 2 mainly arising from fossil fuel combustion. − Carbon capture and sequestration (CCS) has been a promising technology for reducing the emissions of CO 2 to the atmosphere, thereby accomplishing carbon-neutral. − Conventional industrial CO 2 removal from the postcombustion flue gas is typically achieved by aqueous amine solutions; however, it usually involves some other issues, like equipment corrosion, intensive energy consumption, solvent distillation, and water use. − Therefore, developing a new CCS technology with environmentally friendly and energy-efficient features is of great importance. − …”

Validating the Mechanism Underlying the Slacking of the Gate-Opening Behavior in Flexible Metal–Organic Frameworks Arising from the Application of External Force

“…Notably, this study does not claim the superiority of JG-MOF or other MOFs that show small expansions. This is because the structural deformability of flexible MOFs is also related to their unique intrinsic thermal management capabilities: flexible MOFs can deform their structures by absorbing the heat of adsorption, allowing their adsorption performances to be maintained at an elevated level even under non-isothermal conditions which can be found in pressure swing adsorption processes. − The impact is more noticeable in an MOF that demonstrates large structural deformation. Therefore, in some instances, it may be beneficial to permit some extent of slacking and prioritize the inherent thermal management capability.…”

A new honeycomb MOF for C2H4purification and C3H6enrichment by separating methanol to olefin products

“…14 Metal-organic frameworks (MOFs) are highly designable and tuneable because of organic-inorganic hybrid components. [15][16][17][18][19] This specically leads to the unique pore shape/size and surface functionality in MOFs 20 and promotes their varied applications. [21][22][23][24][25][26][27][28] Typically, in gas adsorption and separation elds, many MOFs thus far have focused on separating C 2 or C 3 hydrocarbons from methane (C 1 ), which showed excellent performance and revealed promising application prospects.…”