Amine-functionalized Metal Organic Framework Research Articles

Adsorption of CO2 by Amine-Functionalized Metal–Organic Frameworks Using GCMC and ReaxFF-Based Metadynamics Simulations

Adsorption of CO₂ by Amine-Functionalized Metal–Organic Frameworks Using GCMC and ReaxFF-Based Metadynamics Simulations

Mixed matrix membranes (MMMs) with amine-functionalized ZIF-L for enhanced CO2 separation performance

Amine-functionalized Metal-Organic Frameworks (MOFs) stand out as highly promising materials in membrane separation technology. Nevertheless, the incorporation of amine-functionalized additives may lead to uncontrollable alterations in MOF morphology. Two intact blade-like MOFs (PEI (Polyethylenimine)-ZIF-L and PAMAM (Polyamidoamine)-ZIF-L) were successfully synthesized by controlling the conditions and then introduced into Pebax 2533 to fabricate Mixed Matrix Membranes (MMMs). Hydrogen bonding and other interactions with Pebax can be formed by PEI-ZIF-L and PAMAM-ZIF-L to enhance interfacial compatibility. Simultaneously, a reversible reaction with CO2 molecules can be undergone by the amine groups, resulting in facilitated transport in MMMs. The CO2 separation performance of the MMMs is enhanced by this process, with the facilitation being more pronounced under humid conditions. Under humid conditions, the CO2 permeabilities of Pebax-PEI-ZIF-L (2 wt%) and Pebax-PAMAM-ZIF-L (2 wt%) MMMs were 639.4 Barrer and 702.7 Barrer, respectively, while the CO2/N2 selectivities were 26.68 and 24.35, respectively. Both permeability and selectivity exhibited a significant increase of 200% and 130%, respectively, compared to pure Pebax. Furthermore, the MMMs demonstrated excellent long-term stability during 72 h of continuous operation in a humid environment, showcasing significant potential for industrial applications, particularly in humid flue gas carbon capture.

Light-Switchable N-Alkylation Using Amine-Functionalized MOF

Catalytic N-alkylation is a frequently employed method to synthesize secondary amines and imines, yet selectivity control remains as a challenge that normally requires specialized catalysts under harsh reaction conditions. Here we propose a light-switchable N-alkylation of amines with aromatic halides for selective synthesis of secondary amines and imines, using an amine-functionalized metal-organic framework (MIL-125-NH2) under mild conditions. The MIL-125-NH2 catalyst possesses Lewis acidic sites, which catalyze direct dehalogenative condensation of bromides with primary amines to produce secondary amines in the dark. Upon irradiation, the MIL-125-NH2 reduces molecular oxygen to create oxygen radicals, converting bromides into the corresponding aldehydes to yield imines via a dehydrative coupling with amines. With appropriate acidity, rapid oxygen reduction kinetics, and optimized adsorption of aromatic bromides and generated water, the system catalyzes the conversion of a wide range of substrates, thus featuring it a promising method for applications.

Capturing carbon dioxide from air by using amine-functionalized metal-organic frameworks

Capturing carbon dioxide from air by using amine-functionalized metal-organic frameworks

Solid-State Phosphine Ligand Engineering via Postsynthetic Modification of Amine-Functionalized Metal–Organic Frameworks

Solid-State Phosphine Ligand Engineering via Postsynthetic Modification of Amine-Functionalized Metal–Organic Frameworks

Engineered (NH2)-MIL-125(Ti)/copolymer@MnFe2O4 nanocomposite for synergistic eradication of cancer cells via DOX/pCRISPR delivery

The present study proposed an innovative nanocomposite aimed at enhancing gene and drug delivery for cancer treatment. The nanocomposite was composed of amine-functionalized metal–organic frameworks, (NH2)-MIL-125(Ti), conjugated to poly(aniline-co-para-phenylenediamine), and coated on manganese ferrite nanoparticles that were utilized to co-deliver the chemotherapy drug doxorubicin (DOX) and plasmid CRISPR (pCRISPR) to cancer cells. The investigation focused on whether surface modification with amine groups could improve cellular uptake and transfection efficiency. In addition, the study also utilized an engineered cell-imprinted substrate to mimic the cellular environment and enhance the delivery and expression of edited genes. The results demonstrated the proposed nanocarriers successfully co-delivered DOX and pCRISPR, indicating their potential for combination cancer therapy. Specific highlights include (1) reliable platform for multi-drug delivery based on the (NH2)-MIL-125(Ti)/poly(aniline-co-para-phenylenediamine)/MnFe2O4 nanocomposite structure; (2) hemocompatibility analysis revealed less than 1% hemolysis, pointing to biosafety; (3) amine surface modification enhanced cellular uptake up to 38.3% in A549 cells, improving transfection; (4) the cell-imprinted substrate enhanced therapeutic efficacy by promoting delivery and expression in a physiologically relevant microenvironment. Overall, this study makes significant contributions to gene delivery and expression for cancer therapy. The engineered nanocomposite, amine surface modification, and cell-mimetic substrate employ innovative strategies to augment the efficacy of combination gene and drug therapy against cancer.Graphical

Metal-organic frameworks' latent potential as High-Efficiency osmotic power generators in Thin-Film nanocomposite membranes

This study investigates enhanced osmotic power generation by incorporating metal–organic framework (MOF) nanorods into the thin-film nanocomposite (TFN) membranes for pressure retarded osmosis (PRO) applications. The spotlight is on an innovative membrane, NH2-Ce-BTC-500, which is fabricated utilizing amine-functionalized MOFs (NH2-Ce-BTC), showcasing the synergistic effects of structure and chemistry in optimizing membrane properties for power generation. The NH2-Ce-BTC-500 membrane exhibits a remarkable increase in hydrophilicity, setting a new power density benchmark of 6.9 W/m2. NH2-Ce-BTC-500 outperforms Ce-BTC-500 and pristine TFC membranes by 15 % and 109.1 %, demonstrating the superior performance of amine-functionalized membranes. Furthermore, through physical and chemical characterizations, it is revealed that the MOF-based membranes exhibit increased surface roughness and porosity, indicating the formation of additional water pathways. This enhancement leads to a substantial increase in the water flux, reaching 31.0 LMH in PRO mode, which is a 106 % improvement compared to pristine TFC membranes. This remarkable increase in water flux directly translates to enhanced power generation capacity. In essence, the NH2-Ce-BTC-500 membrane exhibits promising advancements in PRO performance, offering the potential to lower downstream energy consumption and increase power generation efficiency. This research opens up a new paradigm for developing next-generation osmotic power generation. This renewable and energy-efficient solution can address the global energy crisis by leveraging the potential of MOF nanorods in TFN membranes.

Efficient adsorption removal of 2,4-dichlorophenoxyacetic acid using amine-functionalized metal–organic frameworks (MOFs): Performance and mechanisms

2,4-dichlorophenoxyacetic acid (2,4-D) is a widely used herbicide and plant growth regulator worldwide; however, its overdose and improper use would cause severe eco-toxicological effects on aquatic life, plants, and human life. This work synthesized high-quality MIL-101(Cr)-NH2 nanoparticles via a one-pot hydrothermal reaction and used it in pioneer as an amine-functionalized mesoporous metal–organic frameworks (MOFs) adsorbent for 2,4-D removal. The adsorption kinetics results confirmed that MIL-101(Cr)-NH2 obeys the pseud-second-order kinetic model, and the isotherm results imply that it shows multilayer adsorption following the Freundlich model. Compared to state-of-the-art benchmark MOF adsorbent UiO-66-NH2, MIL-101(Cr)-NH2 achieved a superior 2,4-D adsorption capacity of 348.5 mg/g at pH = 7 with a nearly 50 % increase in adsorption removal rate under ambient conditions. Spectroscopy analysis and density functional theory (DFT) calculations revealed that the distinct large pore size, high surface area and porosity of MIL-101(Cr)-NH2 are the essential physical factors for enhancing the diffusion ability of 2,4-D in the framework. Meanwhile, the electrostatic interactions of the metal clusters and aminated benzene ring with the dissociated 2,4-D anion are the dictated binding forces during adsorption. This mechanism was further validated by the adsorption behaviors of other contaminants over the two MOF adsorbents. Furthermore, the MIL-101(Cr)-NH2 nanoparticles can be chemically anchored onto chitosan to form MIL-101(Cr)-NH2/Chitosan foams with feasible recovery ability and it was found that the MIL-101(Cr)-NH2/Chitosan (1/3) foam showed a comparable 2,4-D removal rate to UiO-66-NH2 (52.2 % vs. 57.7 %). This study reported a high-performance aminated MOF adsorbent for 2,4-D removal and the revealed adsorption mechanisms offer an excellent platform for rational design of advanced adsorbents for acidic contaminants adsorption.

Thermally-activated gelatin–chitosan–MOF hybrid aerogels for efficient removal of ibuprofen and naproxen

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most frequently used drugs and have been frequently detected in aquatic environments. This paper demonstrates a thermally-activated gelatin–chitosan and amine-functionalized metal–organic framework (UiO-66–NH2) aerogel (CGC–MOF), which was successfully synthesized for the efficient removal of ibuprofen (IBP) and naproxen (NPX). Various characterization tools were used to systematically analyze the microstructure and physicochemical properties of the synthesized aerogel. In addition, the effect of key reaction parameters as well as batch and continuous-flow fixed-bed column experiments were carried out to elucidate the adsorption process. Several functional groups in the biopolymer network, combined with excellent MOF properties, synergistically couple to form an adsorbent with great performance. The mesoporous aerogel activated at 200 °C (CGC–MOF200) exhibited a high specific surface area (819.6 m2/g) that is valuable in providing abundant adsorption active sites that facilitate the efficient adsorption of IBP and NPX. CGC–MOF200 exhibited an excellent removal of IBP and NPX, accounting to 99.28 % and 96.39 %, respectively. The adsorption process followed the pseudo-second-order kinetics and the Freundlich isotherm models, suggesting heterogeneous and chemisorption adsorption processes. Overall, this work provides new and valuable insights into the development of a promising biopolymer–MOF composite aerogel for environmental remediation.

Application of a manganese dioxide/amine-functionalized metal-organic framework nanocomposite as a bifunctional adsorbent-catalyst for the room-temperature removal of gaseous aromatic hydrocarbons

A high surface area (883 m2·g−1) nanocomposite composed of an amine-functionalized metal–organic framework (NH2-UiO-66 (U6N)) and manganese dioxide (MnO2@U6N) was prepared as bifunctional adsorbent-catalyst for the purification of multiple aromatic volatile organic compounds (VOCs) such as benzene (B), toluene (T), m-xylene (X), and styrene (S), i.e., BTXS. The performance of MnO2@U6N was assessed for BTXS removal both as single- and multi-component systems at room temperature (RT (20 °C)) under dark conditions. MnO2@U6N exhibited superior catalytic-adsorption activity for the RT removal of BTXS. The removal performance of MnO2@U6N against BTXS was then assessed across varying levels of flow rate, VOC concentration, adsorbent/catalyst mass, and relative humidity. To better understand the catalytic-adsorption activity, two types of non-linear kinetic models (pseudo-first-order and pseudo-second-order) were utilized to simulate the experimentally obtained data. In-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) analysis was also conducted to interpret the removal mechanism of BTXS. Their adsorption capacity (mg·g−1) values are estimated to increase in the order of B (21.1) < T (66.0) < X (79.1) < S (129.7). It is suggested that the adsorbed aromatic VOC molecules on the surface of MnO2@U6N should react with active oxygen species (lattice and adsorbed oxygen) to yield the environmentally benigh end products (i.e., carbon dioxide and water) along with various intermediates (e.g., alkoxides, aldehydes, phenolates, carboxylates, and anhydrides). Accordingly, the VOC removal potential of MnO2@U6N has been validated through the synergistic combination between adsorption (primary process) and catalysis (subordinate process) at RT.

Isotherm modeling and techno-economic analysis of a TSA moving bed process using a tetraamine-appended MOF for NGCC applications

Tetraamine-appended metal-organic frameworks (MOF) are a new family of amine-functionalized MOF materials that show potential for CO2 capture from flue gas conditions relevant to natural gas combined cycle (NGCC) power plants. This work presents isotherm modeling of the tetraamine-appended MOF Mg2(dobpdc)(3-4-3)(dobpdc4−=4,4′-dioxidobiphenyl-3,3′dicarboxylate;3-4-3=N,N′bis(3-aminopropyl)-1,4-diaminobutane), process modeling, scale up, and a techno-economic optimization of a moving bed Temperature Swing Adsorption (TSA) process for carbon capture using this sorbent. This MOF exhibits a unique two-step CO2 adsorption profile in three different pressure ranges. Thus, arctangent-based logistic functions and, quadratic and Langmuir models were employed to represent such isotherm behavior. The results of the isotherm model show good fitting vs the experimental data with an RMSE of 0.41. To model the carbon capture process, the isotherm model was embedded into a moving bed contactor model, and this was used to simulate a TSA CO2 capture cycle and evaluate cost-optimal designs considering flue gas from a -650 MWe NGCC power plant. The capital cost model consists of CAPEX correlations for reactors, compressors, ducting, etc., while the operating costs include steam, water, chemicals, and electricity (following NETL's quality guidelines for energy systems studies). A techno-economic optimization of the capture system was performed by using NETL's Framework for the Optimization and Quantification of Uncertainty and Surrogates tool (FOQUS). Results suggest that a moving bed carbon capture system with tetraamine-appended MOF can be competitive compared to conventional MEA solvent-based capture processes for NGCC plants, when a heat recovery efficiency of at least 40% is achieved, and MOF materials can be produced at a cost below -$9/kg.

A Novel Method for Monitoring N-Nitrosamines Impurities Using NH2-MIL-101(Fe) Mediated Dispersive Micro-Solid Phase Extraction Coupled with LC-MS/MS in Biopharmaceuticals

A highly efficient and convenient method for the simultaneous determination of 12 N-nitrosamines (NAs) has been developed using an amine-functionalized metal-organic framework (NH2-MIL-101(Fe)) as sorbent for dispersive micro-solid phase extraction (D-μSPE) coupled with LC-MS/MS in biopharmaceuticals. The experimental variables involved in the extraction process (i.e., amount of the sorbent, extraction time, desorption time, ionic strength, desorption solvent and volume) were optimized to achieve the best extraction efficiency of the target analytes. Under the optimum conditions, the method was successfully validated, showing good linearity in the range of 0.5–3.0 μg/L with determination coefficients (R2) higher than 0.990, repeatability (RSD ≤ 10.0%, spiked level at 2.0 μg/L) and precision (RSD ≤ 8.2%). The limit of detection (LOD) and limit of quantitation (LOQ) were in the range of 0.005–0.025 μg/L and 0.010–0.250 μg/L, respectively. Satisfactory recoveries ranging from 82.4 to 116.8% were obtained by spiking standards at three different concentrations (0.5 μg/L, 2.0 μg/L and 3.0 μg/L). Other validation parameters, including specificity, stability, and robustness, met the validation criteria. More importantly, the plausible adsorption mechanism on NH2-MIL-101(Fe) was proposed by Fourier-transform infrared (FTIR) spectra technique. Finally, this method was successfully applied to detect trace nitrosamines in biopharmaceuticals.

Temperature-vacuum swing adsorption for direct air capture by using low-grade heat

Direct air capture (DAC) is a promising carbon mitigation technology and will likely be part of extensive carbon removal portfolio. Adsorptive DAC is an appropriate option for carbon capture to utilize low-grade heat because of its desirable regeneration temperature and adaptability to be integrated with renewables. Building indoor environment with CO2 concentrations above 1000 ppm provides another suitable scenario for DAC. Herein, DAC using temperature-vacuum swing adsorption (TVSA) is presented and analyzed by integrating various low-grade heat sources in buildings. An amine-functionalized metal organic framework is selected for process simulation, and the performance is compared with those using other sorbents. It indicates that amine-functionalized material has advantages in CO2 productivity and purity. A techno-economic analysis is carried out to explore the benefit of the proposed DAC in buildings. The results show that regeneration by heat pumps at 373 K is the most competitive solution and has 176.7 $·tCO2−1 of the levelized cost of DAC (LCOD). Compared with conventional energy supply, solutions with low-grade heat utilization in buildings could achieve lower carbon intensity and increase by 5.2–25.0% in net LCOD. These results will provide practical guidelines for DAC application with lower energy penalties and costs.

Reduction of energy consumption in post-combustion carbon capture process via amine-functionalized metal-organic frameworks

In this study, CO2 capture performance of ethylenediamine-functionalized Mg-MOF-74 (EDMOF-74) suspended in 30 wt% monoethanolamine (MEA) aqueous solution is analyzed. A CO2 absorption experiment was performed in a bubble column reactor based on EDMOF-74 concentrations of 0.005, 0.01, 0.05, and 0.1 wt% for different ethylenediamine loadings. It shows that EDMOF-74/30 wt% MEA mixtures improve CO2 absorption performance by a maximum of 7.18 % as compared with the base fluid. Subsequent experiment based on large-volume feed gas reveals a less volatile CO2 absorption rate. By adding EDMOF-74 to the 30 wt% MEA aqueous solution in a cyclic CO2 absorption experiment to evaluate its industrial application, an increase in durability is indicated, which implies a reduction in energy consumption during CO2 regeneration. A feasibility study on the reduction of CO2 regeneration energy was investigated in terms of the results of cyclic experiment and the facility status of Boryeong power plant. The CO2 regeneration energy can be reduced by 13.64 %, which corresponds to a decrease of 484,233 MWht/year for 1 unit of the Boryeong power plant. The abovementioned approach is expected to compensate for the disadvantages of MEA in the industrial CO2 capture process, i.e., low CO2 capacity and high CO2 regeneration energy input.

Solvent-free mechanochemical multicomponent preparation of 4H-pyrans catalyzed by Cu2(NH2-BDC)2(DABCO) metal-organic framework

4H-pyrans have been prepared through a mechanochemical multicomponent reaction (MCR) of different aldehydes, malononitrile, and various 1,3-dicarbonyl compounds, catalyzed by an amine-functionalized metal-organic framework (MOF) Cu2(NH2-BDC)2(DABCO) as a heterogeneous catalyst with good to excellent yields.

Study on the Performance of Cellulose Triacetate Hollow Fiber Mixed Matrix Membrane Incorporated with Amine-Functionalized NH2-MIL-125(Ti) for CO2 and CH4 Separation

The increase in the global population has caused an increment in energy demand, and therefore, energy production has to be maximized through various means including the burning of natural gas. However, the purification of natural gas has caused CO2 levels to increase. Hollow fiber membranes offer advantages over other carbon capture technologies mainly due to their large surface-to-volume ratio, smaller footprint, and higher energy efficiency. In this work, hollow fiber mixed matrix membranes (HFMMMs) were fabricated by utilizing cellulose triacetate (CTA) as the polymer and amine-functionalized metal-organic framework (NH2-MIL-125(Ti)) as the filler for CO2 and CH4 gas permeation. CTA and NH2-MIL-125(Ti) are known for exhibiting a high affinity towards CO2. In addition, the utilization of these components as membrane materials for CO2 and CH4 gas permeation is hardly found in the literature. In this work, NH2-MIL-125(Ti)/CTA HFMMMs were spun by varying the air gap ranging from 1 cm to 7 cm. The filler dispersion, crystallinity, and functional groups of the fabricated HFMMMs were examined using EDX mapping, SEM, XRD, and FTIR. From the gas permeation testing, it was found that the NH2-MIL-125(Ti)/CTA HFMMM spun at an air gap of 1 cm demonstrated a CO2/CH4 ideal gas selectivity of 6.87 and a CO2 permeability of 26.46 GPU.

MIL-88B(Fe)-NH2: an amine-functionalized metal-organic framework for application in a sensitive electrochemical sensor for Cd2+, Pb2+, and Cu2+ ion detection.

We propose here an electrochemical platform for multi-heavy metal ion detection in water based on MIL-88B(Fe)-NH2, an amine-functioned metal-organic framework (MOF) for modifying the surface of a glassy carbon electrode (GCE). Herein, MIL-88B(Fe)-NH2 with abundant functionalized amine groups can play the role of capture sites for the enrichment of metal ions before electrochemical oxidation sensing. MIL-88B(Fe)-NH2 was synthesized under optimized conditions through a solvothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. MIL-88B(Fe)-NH2 was then drop-casted on GCE to electrochemically determine the Cd2+, Pb2+ and Cu2+ ion concentrations by differential pulse voltammetry (DPV). The electrochemical sensor exhibits excellent electrochemical performance toward Cd2+, Pb2+ and Cu2+ ions in the large linear ranges of 0.025-1.000 μM, 0.3-10.0 μM and 0.6-10.0 μM with limits of detection that are 2.0 × 10-10 M, 1.92 × 10-7 M and 3.81 × 10-7 M, respectively. The fabricated sensor also shows high reliability and good selectivity. This MIL-88B(Fe)-NH2 application strategy is promising for the evaluation of various heavy metal ions in water.

A Cluster Based Cooperative Kinetic Model for CO2 Adsorption on Amine Functionalized Metal–Organic Frameworks

A new model for the adsorption kinetics of CO2 on amine functionalized metal–organic frameworks Mg2 (dobpdc) and Mn2 (dobpdc) is proposed. The equilibrium adsorption is evaluated using the cooperative lattice theory of Kundu et al. The lattice theory provides a microscopic interpretation of adsorption behavior on the basis of the state of adsorbed CO2: singly adsorbed, chain ends, and chain interiors. On this basis, the proposed kinetic model accounts for the kinetics of singly adsorbed CO2, as well as the kinetics of adsorption into chains. These two kinetic paths have separate yet coupled rate laws. This allows for the accurate description of complex kinetic phenomena observed in low partial pressure CO2 breakthrough curves on mmen-Mg2 (dobpdc). In addition to good numerical agreement with measured data, the approach developed in this work provides a needed microscopic interpretation of measured kinetic data in these systems. This microscopic picture may allow for more targeted material design and a pathway to include additional factors such as the effect of humidity on CO2 adsorption and kinetics.

High-Selective CO2 Capture in Amine-Decorated Al-MOFs.

Amine-functionalized metal-organic framework (MOF) material is a promising CO2 captor in the post-combustion capture process owing to its large CO2 working capacity as well as high CO2 selectivity and easy regeneration. In this study, an ethylenediamine (ED)-decorated Al-based MOFs (named ED@MOF-520) with a high specific area and permanent porosity are prepared and evaluated to study the adsorption and separation of CO2 from N2. The results show that ED@MOF-520 adsorbent displays a superior CO2 capture performance with a CO2/N2 separation factor of 50 at 273 K, 185% times increase in the CO2/N2 separation efficiency in comparison with blank MOF-520. Furthermore, ED@MOF-520 exhibits a moderate-strength interaction with 29 kJ mol-1 adsorption heat for CO2 uptake, which not only meets the requirement of CO2 adsorption but also has good cycle stability. This work provides a promising adsorbent with a high CO2/N2 separation factor to deal with carbon peak and carbon neutrality.

Enhancement of Propadiene/Propylene Separation Performance of Metal-Organic Frameworks by an Amine-Functionalized Strategy.

Here, a hexanuclear Co6(μ3-OH)6 cluster-based metal-organic framework (MOF), [Co6(μ3-OH)6(BTB)2(bpy)3]n (JXNU-15) (bpy = 4,4'-bipyridine), with the 1,3,5-tri(4-carboxyphenyl)benzene (BTB3-) ligand was synthesized for the challenging propadiene/propylene separation. The combination of a large pore volume and a suitable pore environment boosts the significantly high propadiene (C3H4) uptake (311 cm3 g-1 at 298 K and 100 kPa) for JXNU-15. An amine-functionalized MOF of JXNU-15(NH2) was further obtained with the 1,3,5-tri(4-carboxyphenyl)benzene analogue of 3,3″-diamino-5'-(3-amino-4-carboxyphenyl)-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic ligand. The comparative studies of propadiene/propylene(C3H4/C3H6) separation performance between isostructural JXNU-15 and JXNU-15(NH2) are provided. JXNU-15(NH2) exhibits an impressive C3H4 capacity at low pressures with 69.1 cm3 g-1 at 10 kPa, which is twice that of JXNU-15 under the same conditions. Moreover, the separation selectivity of JXNU-15(NH2) is 1.3-fold higher as compared to JXNU-15. JXNU-15(NH2) with enhanced C3H4/C3H6 separation performance was elegantly illustrated by gas separation experiments and theoretical simulations. This work presents an amine-functionalized strategy for the enhancement of the C3H4/C3H6 separation performance of MOF.