Robust Metal-organic Framework Research Articles

MOF/polymer hybrids through in situ free radical polymerization in metal-organic frameworks.

We use the free radical polymerization initiator 4,4'-azobis(cyanovaleric acid) coordinated to the open metal sites of metal-organic frameworks (MOFs) to give rise to highly uniform MOF/polymer hybrids. We demonstrate this strategy on two robust zirconium MOFs (NU-1000 and MOF-808), which are the most effective catalysts for degradation of chemical warfare nerve agents. The resulting hybrid materials maintain their hydrolytic catalytic activity and have substantially improved adhesion to polypropylene and activated carbon textile fibers, yielding highly robust MOF/polymer/textile hybrid systems. These composites are suitable for the green production of active protective clothing and filters capable of detoxifying organophosphorus warfare agents.

Assembly of an iron-based complex into a metal-organic framework: a space confinement strategy for isolation of mono-iron complexes to protect from dimerization.

Non-heme mononuclear iron complexes, especially when supported by tripodal tetradentate ligands, show promising C-H bond activation efficiency in catalytic reactions. Nevertheless, they intrinsically decay readily to their dinuclear form, and the dimerization process is inevitable in homogenous solution, which dramatically hinders their further application. Hence, we demonstrate that the mononuclear iron complex [(TPA)FeII-2L]2+ (L = labile ligands, mainly solvent molecules) was successfully encapsulated in a highly robust metal-organic framework UiO-66 via a two-step "ship-in-a-bottle" strategy. The nearly perfect size matching of the octahedral cages of the host UiO-66 provides ideal space confinement for the guest complex to protect from dimerization and dramatically increases the mono-nuclear complex stability compared to its un-confined state. The successful encapsulation of [(TPA)FeII-2L]2+ in UiO-66 was verified thoroughly by spectroscopy, microscopy, N2 adsorption, and electrochemistry characterization techniques. This work shows that encapsulating an unstable molecular complex in MOFs via a two-step "ship-in-a-bottle" strategy highlights opportunities for extending the heterogenization of homogeneous complexes.

Facile Synthesis of Robust Metal-Organic Framework (MOF-5) for Chromium (VI) Decontamination from Wastewater

Herein, for the first time, we investigate the adsorption performance of nanoZn benzenedicarboxylate metal-organic framework (nanoMOF-5) as an efficient adsorbent material for Cr (VI) decontamination from polluted water. The synthesized Zn MOF-5 was fully characterized via FT-IR, XRD, HRTEM, BET, and TGA techniques. Moreover, the prepared Zn MOF-5 revealed a prominent surface area of 1169.32 m2 g-1, demonstrating its ability to be utilized as a capable adsorbent material. The adsorption profile of Cr (VI) onto the fabricated Zn MOF-5 was performed against the various parameters such as contact time, dosage, and initial Cr (VI) concentration. The optimum dosage from the Zn MOF-5 for 81.03% adsorption of 25 ppm Cr (VI) was 0.5 g L-1 at pH=7 after 15 min. The Cr (VI) decontamination performance of the synthesized Zn MOF-5 recorded the maximum monolayer adsorption capacity of 91.22 mg/g. These data demonstrated that the synthesized nanoZn MOF-5 is a promising adsorbent material for the removal of Cr (VI) from wastewater. Keywords: Zinc Metal-Organic Framework (MOF-5), Cr (VI) Decontamination, Isotherm and Kinetics, Recyclability.

Unveiling Chemically Robust Bimetallic Squarate‐Based Metal–Organic Frameworks for Electrocatalytic Oxygen Evolution Reaction

AbstractHere, this work reports an innovative strategy for the synthesis of chemically robust metal–organic frameworks (MOFs), and applies them as catalysts for the electrocatalytic oxygen evolution reaction (OER). A bimetallic squarate‐based MOF (Sq‐MOF) with a zbr topology serves as an excellent platform for electrocatalytic OER owing to its open porous structure, high affinity toward water, and presence of catalytically active 1D metal hydroxide strips. By regulating the Ni2+ content in a bimetallic squarate MOF system, the electrochemical structural stability toward OER can be improved. The screening of various metal ratios demonstrates that Ni3Fe1 and Ni2Fe1 Sq‐zbr‐MOFs show the best performance for electrocatalytic OER in terms of catalytic activity and structural stability. Ni2Fe1 Sq‐zbr‐MOF shows a low overpotential of 230 mV (at 10 mA cm−2) and a small Tafel slope of 37.7 mV dec−1, with an excellent long‐term electrochemical stability for the OER. Remarkably, these overpotential values of Ni2Fe1 Sq‐zbr‐MOF are comparable with those of the best‐performing layered double hydroxide (LDH) systems and outperforms the commercially available noble‐metal‐based RuO2 catalyst for OER under identical operational conditions.

Reticular chemistry for the rational design of mechanically robust mesoporous merged-net metal-organic frameworks

Reticular chemistry for the rational design of mechanically robust mesoporous merged-net metal-organic frameworks

Fine Tuning the Pore Surface in Zirconium Metal–Organic Frameworks for Selective Ethane/Ethylene Separation

Ethylene is an important chemical feedstock for production of polymers and high-value organic chemicals, and yet its conventional purification process is plagued with high consumption of energy. Metal–organic frameworks (MOFs) provide a suitable adsorption platform for selective ethane/ethylene separation thanks to their structural diversity, tunable pore characteristics, designable pore sizes, and high pore volumes. Although there are empirical design rules like avoiding open metal sites and creating nonpolar pore surfaces for development of adsorptive MOFs, it is still challenging to design robust MOFs that can realize direct ethane-selective separation. Herein, we systematically designed and synthesized three Zr-MOFs based on the assembly of angular ligands and 12-connected Zr6 clusters that feature the pcu network structure. By changing the size and flexibility of the substituent on the angular ligand, we were able to prevent interpenetration and identified NPF-802, which exhibits good C2H6/C2H4 separation performance that is attributed to the bulky and inert tert-butyl groups of its carbazole ligand. This work provides insights for design of ligands of MOFs with suitable pore environments to address important and challenging gas separations.

Synthesis of Nitro Compounds from Nitrogen Dioxide Captured in a Metal-Organic Framework.

Increasing levels of air pollution are driving the need for the development of new processes that take “waste-to-chemicals”. Herein, we report the capture and conversion under ambient conditions of a major air pollutant, NO2, using a robust metal-organic framework (MOF) material, Zr-bptc (H4bptc = 3,3′,5,5′-biphenyltetracarboxylic acid), comprising {Zr6(μ3-O)4(μ3-OH)4(COO)12} clusters linked by 4-connected bptc4– ligands in an ftw topology. At 298 K, Zr-bptc shows exceptional stability and adsorption of NO2 at both low (4.9 mmol g–1 at 10 mbar) and high pressures (13.8 mmol g–1 at 1.0 bar), as measured by isotherm experiments. Dynamic breakthrough experiments have confirmed the selective retention of NO2 by Zr-bptc at low concentrations under both dry and wet conditions. The immobilized NO2 can be readily transformed into valuable nitro compounds relevant to construction, agrochemical, and pharmaceutical industries. In situ crystallographic and spectroscopic studies reveal strong binding interactions of NO2 to the {Zr6(μ3-O)4(μ3-OH)4(COO)12} cluster node. This study paves a circular pathway to enable the integration of nitrogen-based air pollutants into the production of fine chemicals.

A robust metal-organic framework nanofibrous membrane as filter for fast separation of cationic dyes from aqueous solution

• Bio-MOF-1@TPU NFM with robust mechanical properties was successfully fabricated. • Bio-MOF-1@TPU NFM can be used as a filter to separate cationic dye from aqueous solution. • Bio-MOF-1@TPU NFM exhibited fast filtration ability and stable reuse effect. • The separation process was based on the ion-exchange and monolayer adsorption mechanisms. A robust metal-organic framework (MOF) nanofibrous membrane (NFM) was successfully fabricated via electrospinning by employing thermoplastic polyurethane (TPU) as substrate and encapsulating anionic bio-MOF-1 into TPU nanofibers. Characterization with FT-IR, EDS and PXRD confirmed that the crystal structure of bio-MOF-1 maintained well in TPU nanofibers. Based on the ion-exchange mechanism, the as-prepared bio-MOF-1@TPU NFM can be used as a filter for efficient separation of cationic dyes from mixed dyes aqueous solution. Benefiting from the robust mechanical properties of TPU, the bio-MOF-1@TPU NFM can repeatedly withstand the suction filtration pressure without damage, resulting in a very fast dye separation process that completed within 70 s, and a very stable reuse effect that the removal efficiency of MB + was just 9.0 % less than that of the first filtration after five cycles of use. This work will be useful for the design of MOFs NFMs based on electrospinning applied to fast separating organic dyes from practical wastewater.

Ti-based robust MOFs in the combined photocatalytic degradation of emerging organic contaminants

Photocatalysis process is a promising technology for environmental remediation. In the continuous search of new heterogeneous photocatalysts, metal–organic frameworks (MOFs) have recently emerged as a new type of photoactive materials for water remediation. Particularly, titanium-based MOFs (Ti-MOFs) are considered one of the most appealing subclass of MOFs due to their promising optoelectronic and photocatalytic properties, high chemical stability, and unique structural features. However, considering the limited information of the reported studies, it is a hard task to determine if real-world water treatment is attainable using Ti-MOF photocatalysts. In this paper, via a screening with several Ti-MOFs, we originally selected and described the potential of a Ti-MOF in the photodegradation of a mixture of relevant Emerging Organic Contaminants (EOCs) in real water. Initially, two challenging drugs (i.e., the β-blocker atenolol (At) and the veterinary antibiotic sulfamethazine (SMT)) and four water stable and photoactive Ti-MOF structures have been rationally selected. From this initial screening, the mesoporous Ti-trimesate MIL-100(Ti) was chosen as the most promising photocatalyst, with higher At or SMT individual photodegradation (100% of At and SMT photodegradation in 2 and 4 h, respectively). Importantly, the safety of the formed by-products from the At and SMT photodegradation was confirmed. Finally, the At and SMT photodegradation capacity of MIL-100(Ti) was confirmed under realistic conditions, by using a mixture of contaminants in tap drinking water (100% of At and SMT photodegradation in 4 h), proven in addition its potential recyclability, which reinforces the potential of MIL-100(Ti) in water remediation.

Lewis acid-base integrated robust metal-organic framework and reconfigurable composite for solvent-free Biginelli condensation and tandem catalysis with size selectivity

Aiming at environmentally benign catalyses with less energy consumption, reduction in chemical usage and minimization of wastes, metal-organic frameworks (MOFs) combining basic functionality enriched pores and unsaturated metal centers (UMCs) is most promising. Alternatively, astute tuning of channel dimension in these materials can benefit much anticipated size-exclusive catalysis, whereas fabrication of flexible MOF-composite is imperative considering facile applicability over real-life platforms. The pillar-bilayered and hydrolytically robust MOF, built from tri-carboxylate ligand, linear linker and solvent-bound [Cd3(COO)6] secondary building unit exhibits N-functionality enriched porous channels and activation-driven generation of open metal sites. Benefiting from unique bifunctional character, the MOF acts as excellent solvent-free catalyst toward one-pot Biginelli reaction and deacetalization–Knoevenagel condensation under mild condition. Both the reactions transpire with broad substrate scope, high recyclability and superior activity to contemporary materials, wherein single-crystal X-ray diffraction is first time applied as product characterization tool. Judiciously designed control experiments validate individual catalytic routes, thereby substantiating the importance of contrasting pore-functionalities at the interface of structure–property synergism. To the best of three-component coupling and acid-base tandem catalysis, substrates with incompatible molecular dimension to that of the twofold interpenetration generated optimized pores exhibit insignificant conversion and demonstrate unprecedented pore-fitting-actuated size selectivity. In view of practically advanced and eco-friendly substrate design, reconfigurable MOF–cotton fiber composite is fabricated via in situ growth, which delivered excellent yields for both these reactions with comparable reusability to that of pristine framework, delineating a paradigm shift to smart, futuristic and green strategy in synergistic catalysis.

Tunable Confined Aliphatic Pore Environment in Robust Metal-Organic Frameworks for Efficient Separation of Gases with a Similar Structure.

The fine-tuning of the pore structure of metal-organic frameworks (MOFs) is of critical importance to developing energy-efficient processes for the challenging separation of structurally similar molecules. Herein, we demonstrate a strategy to realize a quasi-three-dimensional refinement of the pore structure that utilizes the tunability of ring size and number in polycycloalkane-dicarboxylate ligands. Two hydrolytically stable MOFs with a confined aliphatic pore environment, ZUL-C1 and ZUL-C2, were, for the first time, synthesized and applied in separating low-concentration C2-C3 hydrocarbons from natural gas and ultralow-concentration Xe from used nuclear fuel (UNF) off-gas. Validated by X-ray diffraction and modeling, an expansion of the polycycloalkane moiety enables sub-angstrom contraction in specific directions and forms a pore surface with more alkyl sites, which affords stronger trapping of guest molecules with relatively higher polarizability. The resultant material exhibits record C2H6/CH4 and C3H8/CH4 selectivities coupled with a benchmark low-pressure C2H6 capacity in alkane mixture separation and also a benchmark Xe capacity at extremely diluted feed concentration and record Kr productivity for the Xe/Kr (20:80, v/v) mixture in Xe/Kr separation.

Brønsted Acid-Functionalized Ionic Co(II) Framework: A Tailored Vessel for Electrocatalytic Oxygen Evolution and Size-Exclusive Optical Speciation of Biothiols.

Metal-organic frameworks (MOFs) not only combine globally demanded renewable energy generation and environmental remediation onto a single platform but also rationalize structure-performance synergies to devise smarter materials with remarkable performance. The robust and non-interpenetrated cationic MOF exemplifies a unique bifunctional scaffold for the efficient electrochemical oxygen evolution reaction (OER) and ultrasensitive monitoring of biohazards. The microporous framework containing Brønsted acid-functionalized [Co2(μ2-OH)(CO2)2] secondary building units (SBUs) exhibits remarkable OER performance in 1 M KOH, requiring 410 mV overpotential to obtain 10 mA cm-2 anodic current density, and a low Tafel slope of 55 mV/dec with 93.1% Faradaic efficiency. Apart from the high turnover frequency and electrochemically assessable surface area, steady OER performance over 500 cycles under potentiodynamic and potentiostatic conditions result in long-term catalyst durability. The highly emissive attribute from nitrogen-rich fluorescent struts benefits the MOF in recyclable and selective fluoro-detection of three biothiols (l-cysteine, homocysteine, and glutathione) in water with a fast response time. In addition to colorimetric monitoring in the solid and solution phases, control experiments validate size-exclusive biothiol speciation through molecular-dimension-mediated pore diffusion. The role of SBUs in the OER mechanism is detailed from density functional theory-derived free energy analysis, which also validates the importance of accessible N-sites in sensing via portraying framework-analyte supramolecular interactions.

Self‐Organized Small Molecules in Robust MOFs for High‐Performance Perovskite Solar Cells with Enhanced Degradation Activation Energy

AbstractA brand new strategy to improve the volatility and disordered arrangement of small organic molecule additives within doped perovskite solar cells through the construction of metal–organic frameworks (MOFs) is proposed. The Zn‐TTB, self‐assembling from Zn2+ and 1‐(triazol‐1‐ly)‐4‐tetrazol‐5‐ylmethyl)benzene (TTB), inherits and arranges triazole and tetrazole groups and forms a long‐chain structure surrounding metal nodes. The perovskite precursors grow along with the skeleton of Zn‐TTB and produce a macromolecular intermediate phase via the MOFs‐perovskite interconnection, subsequently forming superior perovskite films with enhanced stability with respect to molecular additives, as evidenced by in situ thermogravimetry‐Fourier transform infrared spectroscopy measurements. Thermal analyses suggest MOF‐doping increases degradation activation energies by up to >174.01 kJ mol–1 compared to the reference sample (162.45 kJ mol–1). Zn‐TTB‐modified devices exhibit promising efficiencies (up to 23.14%) and operational stability in unencapsulated state, even under constant solar light illumination.

High Gravimetric and Volumetric Ammonia Capacities in Robust Metal-Organic Frameworks Prepared via Double Postsynthetic Modification.

Ammonia is a promising energy vector that can store the high energy density of hydrogen. For this reason, numerous adsorbents have been investigated as ammonia storage materials, but ammonia adsorbents with a high gravimetric/volumetric ammonia capacity that can be simultaneously regenerated in an energy-efficient manner remain underdeveloped, which hampers their practical implementation. Herein, we report Ni_acryl_TMA (TMA = thiomallic acid), an acidic group-functionalized metal-organic framework prepared via successive postsynthetic modifications of mesoporous Ni2Cl2BTDD (BTDD = bis(1H-1,2,3,-triazolo [4,5-b],-[4',5'-i]) dibenzo[1,4]dioxin). By virtue of the densely located acid groups, Ni_acryl_TMA exhibited a top-tier gravimetric ammonia capacity of 23.5 mmol g-1 and the highest ammonia storage of 0.39 g cm-3 at 1 bar and 298 K. The structural integrity and ammonia storage capacity of Ni_acryl_TMA were maintained after ammonia adsorption-desorption tests over five cycles. Temperature-programmed desorption analysis revealed that the moderate strength of the interaction between the functional groups and ammonia significantly reduced the desorption temperature compared to that of the pristine framework with open metal sites. The structures of the postsynthetic modified analogues were elucidated based on Pawley/Rietveld refinement of the synchrotron powder X-ray diffraction patterns and van der Waals (vdW)-corrected density functional theory (DFT) calculations. Furthermore, the ammonia adsorption mechanism was investigated via in situ infrared and vdW-corrected DFT calculations, revealing an atypical guest-induced binding mode transformation of the integrated carboxylate. Dynamic breakthrough tests showed that Ni_acryl_TMA can selectively capture traces of ammonia under both dry and wet conditions (80% relative humidity). These results demonstrate that Ni_acryl_TMA is a superior ammonia storage/capture material.

One‐Step C2H4Purification from Ternary C2H6/C2H4/C2H2Mixtures by a Robust Metal–Organic Framework with Customized Pore Environment

AbstractOne‐step C2H4purification from ternary C2H6/C2H4/C2H2mixtures by a single adsorbent is of great industrial significance, but few adsorbents achieve this separation. Herein, we report a robust metal–organic framework (MOF) that possesses methyl‐decorated nonpolar pores and shows one‐step C2H4purification (purity >99.9 %) from binary C2H6/C2H4mixtures and ternary C2H6/C2H4/C2H2mixtures. The methyl groups in pores provide a suitable pore environment to simultaneously enhance the adsorption capacity for C2H2and C2H6compared to C2H4. Simulations revealed the multiple interactions between C2H6or C2H2molecules and the pore wall, while the interactions with C2H4molecules are weak and also unfavorable due to the repulsion from methyl groups in pores. The MOF displays high C2H6and C2H2uptakes and benchmark C2H6/C2H4selectivity (2.2), surpassing all of the reported MOFs for one‐step C2H4purification from ternary C2H6/C2H4/C2H2mixtures.

One-Step C2 H4 Purification from Ternary C2 H6 /C2 H4 /C2 H2 Mixtures by a Robust Metal-Organic Framework with Customized Pore Environment.

One-step C2 H4 purification from ternary C2 H6 /C2 H4 /C2 H2 mixtures by a single adsorbent is of great industrial significance, but few adsorbents achieve this separation. Herein, we report a robust metal-organic framework (MOF) that possesses methyl-decorated nonpolar pores and shows one-step C2 H4 purification (purity >99.9 %) from binary C2 H6 /C2 H4 mixtures and ternary C2 H6 /C2 H4 /C2 H2 mixtures. The methyl groups in pores provide a suitable pore environment to simultaneously enhance the adsorption capacity for C2 H2 and C2 H6 compared to C2 H4 . Simulations revealed the multiple interactions between C2 H6 or C2 H2 molecules and the pore wall, while the interactions with C2 H4 molecules are weak and also unfavorable due to the repulsion from methyl groups in pores. The MOF displays high C2 H6 and C2 H2 uptakes and benchmark C2 H6 /C2 H4 selectivity (2.2), surpassing all of the reported MOFs for one-step C2 H4 purification from ternary C2 H6 /C2 H4 /C2 H2 mixtures.

Separation of naphtha on a series of ultramicroporous MOFs: A comparative study with zeolites

Naphtha separation is of significant importance for refineries to make full use of oil and to reduce the cost of refining. In the recent years, scientists have devoted great efforts to developing novel porous materials such as metal-organic frameworks (MOFs) for the separation of naphtha. However, previous investigations have been limited to single-component or 3- to 5-component model systems. Separation of full range hydrocarbon mixture such as naphtha has rarely been explored. In this work, we carry out a comprehensive study on the separation of alkane isomers as well as full range naphtha mixture by a series of robust microporous MOFs, e.g., Zr-abtc, Al-bttotb, Co-fa, in comparison with representative zeolite materials, e.g., ZSM-5 and zeolite 5A. We find that Al-bttotb and Co-fa, which can separate monobranched and dibranched alkanes through complete molecular exclusion, show superior separation performance for naphtha mixtures. This work may shed light on strategies for developing adsorbents with optimal performance for naphtha separation and ultimately realizing the industrialization of MOF-based separation technologies.

Stable Bimetallic Metal–Organic Framework with Dual-Functional Pyrazolate-Carboxylate Ligand: Rational Construction and C2H2/CO2 Separation

With the guidance of the hard/soft acid/base principle, we adopt a strategy to construct a novel robust metal–organic framework (MOF) by using a dual-functional ligand to coordinate with different types of metal ions in a one-pot reaction through coordination self-selection. A bimetallic MOF, namely BUT-85 (BUT = Beijing University of Technology), has been successfully synthesized with a rationally designed pyrazolate-carboxylate ligand. Its robust [Ni2(OH)(H2O)2Pz3]n chain (Pz = pyrazolate) with bridging OH–/H2O and pyrazolate groups is reported for the first time. This material shows good chemical stability in water and aqueous solutions with a pH range from 3 to 13. In addition, BUT-85 exhibits preferential adsorption behavior of C2H2 over CO2. It is proposed to be attributed to the abundant exposed bridging OH–/H2O sites in [Ni2(OH)(H2O)2Pz3]n chains, which is supported by the results of molecular simulations. Column breakthrough experiments further confirm that this MOF can realize efficient C2H2/CO2 separation. This strategy can not only enrich the structural library of MOFs but also optimize their properties and functions for promoting applications.

A strongly hydrophobic ethane-selective metal-organic framework for efficient ethane/ethylene separation

The removal of ethane (C2H6) from ethylene (C2H4) is of great importance to afford polymer-grade C2H4 with purity greater than 99.95% as feedstock to produce polyethylene. Adsorptive separation with C2H6-selective metal-organic frameworks (MOFs) can directly produce high-purity C2H4, which has shown bright prospects for replacing the energy-intensive cryogenic distillation. Herein, we demonstrate a robust zirconium MOF possessing hydrophobic pores and oxygen-rich groups, namely MOF-841, can preferentially adsorb C2H6 over C2H4. Experimental adsorption isotherms and breakthrough show high separation performance for the gas mixture of C2H6 and C2H4 due to ultrahigh C2H6 uptake capacity (4.7 mmol/g) and distinctive C2H6/C2H4 uptake ratio (1.35) of MOF-841 at 298 K and 100 kPa. Computational studies reveal that aromatic rings and carboxylate oxygen atoms pointing towards the pore ascribed to trapping C2H6 through synergistic effects arising from multiple van der Waals interactions including C-H∙∙∙π and C-H···O, which are more potent than C2H4-framework interactions.

Tuning the Pore Environment of MOFs toward Efficient CH4/N2 Separation under Humid Conditions

Adsorption separation technology using adsorbents is promising as an alternative to the energy-demanding cryogenic distillation of natural gas (CH4/N2) separation. Although a few adsorbents, such as metal-organic frameworks (MOFs), with high performance for CH4/N2 separation, have been reported, it is still challenging to target the desired adsorbents for the actual CH4/N2 separation under humid conditions because the adsorption capacity and selectivity of the adsorbents might be mainly dampened by water vapor. Except for the high CH4 uptake and CH4/N2 selectivity, the adsorption material should simultaneously have excellent stability against moisture and relatively low-water absorption affinity. Here, we tuned the ligands and metal sites of reticular MOFs, Zn-benzene-1,4-dicarboxylic acid-1,4-diazabicyclo[2.2.2]octane (Zn-BDC-DABCO) (DMOF), affording a series of isostructural MOFs (DMOF-N, DMOF-A1, DMOF-A2, and DMOF-A3). Because of the finely engineered pore size and introduced aromatic rings in the functional DMOF, gas sorption results reveal that the materials show improved performance with a benchmark CH4 uptake of 37 cm3/g and a high CH4/N2 adsorption selectivity of 7.2 for DMOF-A2 at 298 K and 1.0 bar. Moisture stability experiments show that DMOF-A2 is a robust MOF with low water vapor capacity even at ∼40% relative humidity (RH) because of the presence of more hydrophobic aromatic rings. Breakthrough experiments verify the excellent CH4/N2 separation performances of DMOF-A2 under high humidity.