CH4 Adsorption Research Articles

Hydroxyl-functionalized linker endows an ultra-microporous aluminum based metal–organic framework with electronegative site for enhancing ethane/ethylene separation

Efficient purification of ethylene (C2H4) from the cracking gas containing a small amount of ethane (C2H6) by selective adsorption of C2H6 is meaningful but remains challenging. Aluminum-based metal–organic frameworks (Al-MOFs) with ultra-microporous structure show preferential adsorption of C2H6 over C2H4, relying on the existence of multiple hydrogen bonding acceptors (e.g., AlO6 polyhedra) for C2H6 molecule in the confined pores. However, most Al-MOFs exhibit limited C2H6/C2H4 selectivity (<2), which lack other strong preferential binding sites for C2H6. Here we report that a hydroxyl functionalized Al-MOF (i.e., CAU-1-OH) exhibits notably improved C2H6/C2H4 selectivity (2.13) and C2H6 uptake (3.95 mmol g−1) at 298 K and 1 bar compared to its amino-functionalized counterpart, CAU-1-NH2. Prior to experiment, theoretical calculations were performed, revealing that O atom from hydroxyl group in CAU-1-OH acts as a fairly strong hydrogen bond acceptor due to its more negative charge than N atom in CAU-1-NH2. The in-situ infrared experiment further confirmed the formation of multiple hydrogen bonds (C–H⋅⋅⋅O) between CAU-1-OH and C2H6 molecules, which plays vital role for C2H6-selective capture. The actual potential for C2H4 purification was fully demonstrated by dynamic breakthrough experiments, in which CAU-1-OH displayed excellent separative performance from C2H6/C2H4 (1/15, v/v) mixture. Moreover, the structural stability and excellent recyclability suggested and the promise for cost-effective industrial application in C2H6/C2H4 separation.

Rational design of carbon materials with tailored pore structure for efficient separation of CH4/N2 mixture

The highly-efficient separation of CH4/N2 mixture on carbon materials is significantly hindered by the inherent trade-off that exists between CH4 adsorption capacity and CH4/N2 separation selectivity. Herein, we have constructed a type of novel carbon materials (PGC-x) with well-controlled ultramicropores ranging from 0.48 to 0.57 nm for CH4/N2 separation. The Zn-based salt template was in-situ confined into the polymer framework during the co-assembly of phloroglucinol and glyoxylic acid. The subsequent evaporation of Zn at high temperature gives rise to the adjustable ultramicropore structure, effectively devoid of mesopores and macropores. Benefiting from the optimal pore size of 0.50 nm, PGC-1 demonstrated high CH4 uptake of up to 1.50 mmol/g. Meanwhile, the CH4/N2 (15/85 and 85/15, v/v) separation selectivity of PGC-1 at 298 K and 1.0 bar reached 5.8 and 6.0, respectively. Dynamic breakthrough experiments proved that PGC-1 could be used as efficient adsorbent for capturing low or high concentration of CH4 from N2. This work offers a promising design principle for optimizing porous structure of carbon materials, with the aim of minimizing the selectivity-capacity trade-off that often arises in the separation of diverse gas pairs.

Supramolecular Entanglement in a Hydrogen‐Bonded Organic Framework Enables Flexible‐Robust Porosity for Highly Efficient Purification of Natural Gas

AbstractThe development of porous materials with flexible‐robust characteristics shows some unique advantages to target high performance for gas separation, but remains a daunting challenge to achieve so far. Herein, we report a carboxyl‐based hydrogen‐bonded organic framework (ZJU‐HOF‐8a) with flexible‐robust porosity for efficient purification of natural gas. ZJU‐HOF‐8a features a four‐fold interpenetrated structure with dia topology, wherein abundant supramolecular entanglements are formed between the adjacent subnetworks through weak intermolecular hydrogen bonds. This structural configuration could not only stabilize the whole framework to establish the permanent porosity, but also enable the framework to show some flexibility due to its weak intermolecular interactions (so‐called flexible‐robust framework). The flexible‐robust porosity of ZJU‐HOF‐8a was exclusively confirmed by gas sorption isotherms and single‐crystal X‐ray diffraction studies, showing that the flexible pore pockets can be opened by C3H8 and n‐C4H10 molecules rather by C2H6 and CH4. This leads to notably higher C3H8 and n‐C4H10 uptakes with enhanced selectivities than C2H6 over CH4 under ambient conditions, affording one of the highest n‐C4H10/CH4 selectivities. The gas‐loaded single‐crystal structures coupled with theoretical simulations reveal that the loading of n‐C4H10 can induce an obvious framework expansion along with pore pocket opening to improve n‐C4H10 uptake and selectivity, while not for C2H6 adsorption. This work suggests an effective strategy of designing flexible‐robust HOFs for improving gas separation properties.

Structural Characterisation of Zeolites Derived from Lithium Extraction: Insights into Channel- and Cage-Type Frameworks

This study investigates the structural and adsorption characteristics of channel- and cage-type zeolites obtained through lithium extraction. Through XRD, FT-IR spectroscopy, and adsorption isotherm analyses, distinct adsorption behaviours of CH4 and CO2 were observed in both zeolite types. Cage-type zeolites exhibited higher adsorption capacities attributed to their structural advantages, highlighting the importance of structural framework selection in determining adsorbent efficacy. The presence of structural defects and an amorphous phase influenced adsorption behaviours, while thermodynamic data underscored the role of adsorbate properties. Kinetics studies revealed the influence of the structural framework on CH4 adsorption and CO2 adsorption kinetics. Analysis of adsorbate–adsorbent interactions demonstrated robust interactions, particularly with LPM16-Y. These findings offer insights into the potential applications of zeolites in gas adsorption processes, emphasising the importance of structural properties and adsorbate characteristics in determining adsorption performance.

Topology Reconfiguration of Anion-Pillared Metal-Organic Framework from Flexibility to Rigidity for Enhanced Acetylene Separation.

Flexible metal-organic framework (MOF) adsorbents commonly encounter limitations in removing trace impurities below gate-opening threshold pressures. Topology reconfiguration can fundamentally eliminate intrinsic structural flexibility, yet remains a formidable challenge and is rarely achieved in practical applications. Herein, a solvent-mediated approach is presented to regulate the flexible CuSnF6-dpds-sql (dpds = 4,4''-dipyridyldisulfide) with sql topology into rigid CuSnF6-dpds-cds with cds topology. Notably, the cds topology is unprecedented and first obtained in anion-pillared MOF materials. As a result, rigid CuSnF6-dpds-cds exhibits enhanced C2H2 adsorption capacity of 48.61 cm3 g-1 at 0.01bar compared to flexible CuSnF6-dpds-sql (21.06 cm3 g-1). The topology transformation also facilitates the adsorption kinetics for C2H2, exhibiting a 6.5-fold enhanced diffusion time constant (D/r2) of 1.71 × 10-3 s-1 on CuSnF6-dpds-cds than that of CuSnF6-dpds-sql (2.64 × 10-4 s-1). Multiple computational simulations reveal the structural transformations and guest-host interactions in both adsorbents. Furthermore, dynamic breakthrough experiments demonstrate that high-purity C2H4 (>99.996%) effluent with a productivity of 93.9mmol g-1 can be directly collected from C2H2/C2H4 (1/99, v/v) gas-mixture in a single CuSnF6-dpds-cds column.

Molecular simulations of the effects of CO2 and N2 injection on CH4 adsorption, coal porosity and permeability

Molecular simulations of the effects of CO2 and N2 injection on CH4 adsorption, coal porosity and permeability

Conversion of the greenhouse gases CH4 and CO2 to CH3COOH using transition metal Clusters: Two birds with one stone

Density functional theoretical studies are performed to investigate the conversion of carbon dioxide and methane to acetic acid using group 10 transition metal clusters in their free and carbon-supported states. The adsorption of CH4 is more feasible than CO2 for most of the clusters and the reaction is initiated with the adsorption of CH4 over the catalysts. Energy barrier for the reaction is reduced significantly using the clusters compared to that in free state which is further reduced when coronene is used as a carbon support. Among various metal clusters, the barrier is found to be the lowest for Ni3.

Pd and Pd-B modified g-CN monolayer as innovative sensor and scavenger for CO, NO2, C2H2 and C2H4: A DFT study

The prompt detection of toxic gases like CO, NO2, C2H2, and C2H4 is crucial for both environmental preservation and industrial safety. In this work, we investigate the adsorption behavior and sensing performance of these four gases on both intrinsic g-CN and g-CN modified with single Pd atom and Pd-B pair, denoted as Pd-g-CN and Pd-B-g-CN, respectively, utilizing the first-principles calculations. The results indicate that the introduction of Pd atom and Pd-B pair significantly enhances the adsorption effect of g-CN monolayer toward these gases, with adsorption energies ranging from − 0.44 eV to − 1.43 eV. Furthermore, all adsorptions are identified as chemisorption, with the adsorption strength following the order of NO2 > CO > C2H4 > C2H2. Additionally, the adsorption of NO2, C2H2, and C2H4 induces notable changes in the work function of Pd-g-CN and Pd-B-g-CN, as well as approximately a 20-time increase in the bandgap of Pd-g-CN. Moreover, the Pd-g-CN and Pd-B-g-CN monolayers exhibit reasonable recovery times for C2H2 and C2H4, measured as 0.04 s and 6.40 μs at 298 K, respectively. Furthermore, NO2 can be rapidly desorbed from the Pd-B-g-CN surface at 398 K, with a short recovery time of 8.17 s. Therefore, the Pd-g-CN and Pd-B-g-CN monolayers can be regarded as potential gas-sensitive materials for the detection of C2H2 and C2H4 at room temperature, respectively. These research findings provide robust theoretical support for the design of novel gas sensors and efficient toxic gas adsorbents.

Regulation research on weak co-adsorption and nonsteady-state capture for C6H6/CO2 over carbon materials

With the intention of capturing both benzene (C6H6) and carbon dioxide (CO2) from indoor air, it is assuring of getting both C6H6 and CO2 simultaneously adsorbed over activated carbon materials. Thus, in this study, how adsorption of C6H6 and CO2 performs over single-wall carbon materials is minutely investigated via density function theory (DFT). Specifically speaking, direct electronic interaction between C6H6 and CO2, co-adsorption features and nonsteady-state capture processes of C6H6/CO2 over single-wall carbon nanotube (CNT) as well as regulation of CNTs towards more stable adsorption are main contents in this study. According to results, C6H6 and CO2 are weakly mutually attracted because of limited electrostatic attraction forces and hydrogen-bond effects, which are also the major reason for consequent weak co-adsorption state over pure CNT. In the meantime, owing to repulsive forces of π-orbital electrons from pure CNT to C6H6, both of C6H6 and CO2 could be only captured by pure CNT in nonsteady state. However, with phosphorus (P) and aluminum (Al) embedded as dopants, surficial electron distribution is altered to a large degree and local electron-enriched centers of modified CNTs are formed to enhance connection with C6H6/CO2, especially stronger electrostatic positron–electron attraction and faster capture speeds from free-state to adsorption-state at relatively high temperatures. Overall, this study provides plentiful information of utilizing single-wall carbon materials for fast indoor air purification in a passive way.

Optimized separation of C2H2 from binary mixtures of C2H2/CO2 and C2H2/C2H4 by coordinative copper(I) metal nodes modified from HKUST-1

Acetylene (C2H2), an industrially important gas, is produced by steam cracking of hydrocarbons and inevitably contains traces of ethylene (C2H4) and carbon dioxide (CO2) as impurities. Metal-organic frameworks (MOFs) and further post-modified MOFs are versatile and promising adsorbents for energy-efficient C2H2/C2H4 and C2H2/CO2 separation by selective adsorption of C2H2 compared to energy-consuming conventional methods. Herein, Cu(I) ion generated structures from post-synthetic modification of HKUST-1 are chosen as C2H2 selective sites over both C2H4 and CO2 gases. Protective Cu(I) ions were generated by post-coordinative reduction of Cu(II) nodes of a HKUST-1 using hydroquinone as a reducing agent to create robust C2H2 adsorptive sites. In the metal node reduced to Cu(I) by hydroquinone (HKUST-1-HQ), C2H2 selectivity was enhanced not only for C2H2/CO2 but also C2H2/C2H4 by the presence of the Cu(I) site, by virtue of the copper(I)-alkynyl chemistry. In a breakthrough test, separation of C2H2 and C2H4 did not occur at the coordinatively unsaturated site (HKUST-1), whereas separation capability appeared after monovalent copper was introduced. Enhanced C2H2/CO2 separation was also observed for HKUST-1-HQ. The adsorption behavior of C2H2 (triple bond), C2H4 (double bond), and CO2 (opposite quadruple moment) at the copper(II) open metal site and copper(I) site originating from the same structure respectively is studied to understand the C2H2 gas sorption. In HKUST-1-HQ, the study of four types of possible Cu structures (Nodes II, III, IV, and V) and adsorbates revealed that Node IV is a preferential site over the other three sites, and the CUS site (bare HKUST-1). DFT computational simulation successfully demonstrated that the Node IV type Cu(I) is a plausible adsorption site for C2H2. Overall, HKUST-1-HQ exhibits greater moisture stability, improved selectivity, and repeatability as C2H2 adsorbent.

First-principles study of CH2O, CH4, Cl2, HCN, and CNCl gas adsorption behavior by h-BN boron site modification

The potential application of metallic boron bit-doped hexagonal boron nitride monolayers (h-BN@M, M = Fe, Sn, Cu, Zn) as materials for the detection of hazardous gases (CH2O, CH4, Cl2, HCN, and CNCl) has been investigated based on the first nature principle. h-BN@Fe exhibits chemisorptive properties for the adsorption of HCN and CNCl and h-BN@Sn exhibits chemisorption and appropriate humidity resistance. The recovery time of HCN on the h-BN@Fe surface and CNCl on the h-BN@Sn surface was significantly shortened under the 392 K ultraviolet light attempt frequency. In the presence of an applied electric field, HCN and CNCl on the h-BN@Fe surface and CNCl on the h-BN@Sn surface showed adjustable recovery times. This suggests that it is possible to design gas sensing devices with good adsorption characteristics on metallic boron bit-doped hexagonal boron nitride monolayers. In the future, the performance of these materials for the detection of hazardous gases will be improved by changing their structure and composition.

Auxiliary ligand influence on interpenetration and C2H2/CO2 separation in NDI based isoreticular MOFs

Selective separation of C2H2 from CO2 mixtures promises a critical industrial process to produce high-purity C2H2 but challenging due to their similar physical properties and molecular sizes/shapes. Naphthalenediimide (NDI) ligand-based metal − organic frameworks (MOFs) exhibit potential in selective adsorption of C2H2 due to NDI’s high affinity to C2H2 molecules. Here, three iso-reticular NDI based MOFs (denoted as FJU-109, 110 and 111) are obtained by tuning interpenetration using auxiliary ligands of different lengths. Based on the actual column breakthrough experiments, FJU-111 can achieve separation C2H2/CO2 mixture, with a separation selective of 2.2. Calculation of the binding energy shows that C-H…O interactions between guest and O atom from NDI ligand play a dominant role in elective recognition of acetylene.

100% selective methane conversion to C1 products over Ni/CeO2 nanorods

Selective CH4 upgrading to C1 products and avoiding over oxidation remains a key challenge. Here, we develop a highly efficient Ni/CeO2 nanorods containing both uniformly dispersed Ni-single-site and NiOx/CeO2 heterojunction for 100 % selectively CH4 conversion to C1 products (CH3OH, HCHO, CH3OOH and HCOOH). Under optimized photocatalytic experimental conditions, a high C1 product yield of 5.6 mmol g-1h−1 was obtained with 100 % selectivity with presence of H2O2. Mechanism study showed that the Ni-single-site together with formed oxygen vacancy (Ov) facilitated CH4 adsorption and activation. The terminal O atom of adsorbed ·OOH can fill the Ov, with the remaining *OH initiating *CH3 dehydrogenation and forming *CH2OH, which further reacts with ·OH to generate the main product HCHO. During the whole photocatalytic process, the formed NiOx/CeO2 heterojunction promoted carrier separation and enhanced catalytic performance.

Ultrafine Pt Nanoparticles on Defective Tungsten Oxide for Photocatalytic Ethylene Synthesis.

The selective conversion of ethane (C2H6) to ethylene (C2H4) under mild conditions is highly wanted, yet very challenging. Herein, it is demonstrated that a Pt/WO3-x catalyst, constructed by supporting ultrafine Pt nanoparticles on the surface of oxygen-deficient tungsten oxide (WO3-x) nanoplates, is efficient and reusable for photocatalytic C2H6 dehydrogenation to produce C2H4 with high selectivity. Specifically, under pure light irradiation, the optimized Pt/WO3-x photocatalyst exhibits C2H4 and H2 yield rates of 291.8 and 373.4µmolg-1h-1, respectively, coupled with a small formation of CO (85.2µmolg-1h-1) and CH4 (19.0µmolg-1h-1), corresponding to a high C2H4 selectivity of 84.9%. Experimental and theoretical studies reveal that the vacancy-rich WO3-x catalyst enables broad optical harvesting to generate charge carriers by light for working the redox reactions. Meanwhile, the Pt cocatalyst reinforces adsorption of C2H6, desorption of key reaction species, and separation and migration of light-induced charges to promote the dehydrogenation reaction with high productivity and selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory calculation expose the key intermediates formed on the Pt/WO3-x catalyst during the reaction, which permits the construction of the possible C2H6dehydrogenation mechanism.

Biomass-derived sulfur-doped porous carbon for CO2 and CH4 selective adsorption

Series of sulfur-doped porous carbons were prepared by using glucose as carbon source and sodium dodecyl sulfate as sulfur source to synthesize sulfur-based carbon precursor and KOH as activator. Pore structure parameters and sulfur content of the prepared carbon materials could be facility regulated by controlling the ratio of KOH/sulfur-based carbon precursor and activation temperature, and their adsorptive separation properties towards CO2 and CH4 were investigated. Results showed that the higher the ultra-microporous volume and the S content of the prepared sulfur-doped porous carbon were, the larger the CO2 and the CH4 adsorption capacity were. The maximum adsorption capacity of CO2 (6.54 mmol/g, 273.15 K and 101 kPa, hereinafter) and CH4 (2.98 mmol/g), and the excellent selectivity of CO2/N2 (75.7) and CH4/N2 (22.8) were achieved by ACS-700-2 because of its higher ultra-microporous pore volume and the highest S content. Permeation experiment, cycle stability test and adsorption thermodynamics experiment show that the prepared S-doped porous carbon had good application potential in the separation and enrichment of CO2 in flue gas and CH4 in coalbed methane. In addition, the pore formation mechanism of sulfur-doped porous carbon was discussed.

Low-Hydrophilic HKUST-1/Polymer Extrudates for the PSA Separation of CO2/CH4.

HKUST-1 is an MOF adsorbent industrially produced in powder form and thus requires a post-shaping process for use as an adsorbent in fixed-bed separation processes. HKUST-1 is also sensitive to moisture, which degrades its crystalline structure. In this work, HKUST-1, in the form of crystalline powder, was extruded into pellets using a hydrophobic polymeric binder to improve its moisture stability. Thermoplastic polyurethane (TPU) was used for that purpose. The subsequent HKUST-1/TPU extrudate was then compared to HKUST-1/PLA extrudates synthesized with more hydrophilic polymer: polylactic acid (PLA), as the binder. The characterization of the composites was determined via XRD, TGA, SEM-EDS, and an N2 adsorption isotherm analysis. Meanwhile, the gas-separation performances of HKUST-1/TPU were investigated and compared with HKUST-1/PLA from measurements of CO2 and CH4 isotherms at three different temperatures, up to 10 bars. Lastly, the moisture stability of the composite materials was investigated via an aging analysis during storage under humid conditions. It is shown that HKUST-1's crystalline structure was preserved in the HKUST-1/TPU extrudates. The composites also exhibited good thermal stability under 523 K, whilst their textural properties were not significantly modified compared with the pristine HKUST-1. Furthermore, both extrudates exhibited larger CO2 and CH4 adsorption capacities in comparison to the pristine HKUST-1. After three months of storage under atmospheric humid conditions, CO2 adsorption capacities were reduced to only 10% for HKUST-1/TPU, whereas reductions of about 25% and 54% were observed for HKUST-1/PLA and the pristine HKUST-1, respectively. This study demonstrates the interest in shaping MOF powders by extrusion using a hydrophobic thermoplastic binder to operate adsorbents with enhanced moisture stability in gas-separation columns.

First-Principles Study of Adsorption of CH4 on a Fluorinated Model NiF2 Surface.

Electrochemical fluorination on nickel anodes, also known as the Simons' process, is an important fluorination method used on an industrial scale. Despite its success, the mechanism is still under debate. One of the proposed mechanisms involves higher valent nickel species formed on an anode acting as effective fluorinating agents. Here we report the first attempt to study fluorination by means of first principles investigation. We have identified a possible surface model from the simplest binary nickel fluoride (NiF2). A twice oxidized NiF2(F2) (001) surface exhibits higher valent nickel centers and a fluorination source that can be best characterized as an [F2]- like unit, readily available to aid fluorination. We have studied the adsorption of CH4 and the co-adsorption of CH4 and HF on this surface by means of periodic density functional theory. By the adsorption of CH4, we found two main outcomes on the surface. Unreactive physisorption of CH4 and dissociative chemisorption resulting in the formation of CH3F and HF. The co-adsorption with the HF gave rise to four main outcomes, namely the formation of CH3F, CH2F2, CH3 radical, and also physisorbed CH4.

Promoting effect and kinetic analysis of Fe-Co bimetallic doping on the LaMnO3 catalytic activity for methane combustion

To enhance the catalyst’s properties, a modified sol–gel method is developed in this study, and a unique perovskite catalyst, LaMnxFeyCo1-x-yO3, is successfully synthesized by doping Fe-Co into the lattice of LaMnO3. The catalytic activity of the synthesized catalysts is initially determined by applying them to methane oxidation. Then, the structural, chemical, and surface properties of these catalysts are systematically evaluated utilizing XRD, BET, O2-TPD, H2-TPR, SEM, and XPS analyses. The modified LaMn0.8Fe0.15Co0.05O3 is shown to exhibit excellent activity (T90 at 486.5 ℃) in methane catalytic combustion, comparable to several standard noble metal materials. Experimental findings indicate that such perovskite structures have a larger specific surface area, an elevated molar ratio of Mn4+, desirable low-temperature reducibility, and excellent oxygen mobility relative to the original LaMnO3. Meanwhile, more efficient electron transfer from Mn4+/Mn3+ redox cycles, as well as the emergence of oxygen defects, significantly contribute to the robust interaction between Fe-Co and LaMnO3. Further reaction kinetic analysis is conducted to determine changes in species components and identify possible catalytic pathways. Notably, Fe-Co co-doping leads to an improvement in the increase of lattice oxygen and CH4 adsorption. In addition, the MVK kinetic mechanism governs methane combustion over LaMn0.8Fe0.15Co0.05O3. This study provides new insights into enhancing energy conversion performance and efficient utilization of ventilation air methane (VAM) through the implementation of highly efficient perovskites.

A Highly Stable Microporous Calcium-Based MOF for C2H2/CO2 Separation with Low Regenerative Energy.

Most of the porous materials used for acetylene/carbon dioxide separation have the problems of poor stability and high energy requirements for regeneration, which significantly hinder their practical application in industries. Here, we report a novel calcium-based metal-organic framework (NKM-123) with excellent chemical stability against water, acids, and bases. Additionally, it has exceptional thermal stability, retaining its structural integrity at temperatures up to 300 °C. This material exhibits promising potential for separating C2H2 and CO2 gases. Furthermore, it demonstrates an adsorption heat of 29.3 kJ mol-1 for C2H2, which is lower than that observed in the majority of MOFs used for C2H2/CO2 separations. The preferential adsorption of C2H2 over that of CO2 is confirmed by dispersion-corrected density functional theory (DFT-D) calculations. In addition, the potential of industrial feasibility of NKM-123 for C2H2/CO2 separation is confirmed by transient breakthrough tests. The robust cycle performance and structural stability of NKM-123 during multiple breakthrough tests show great potential in the industrial separation of light hydrocarbons.

Optimizing Trace Acetylene Removal from Acetylene/Ethylene Mixture in a Flexible Metal-Organic Framework by Crystal Downsizing.

Improving the gas separation performance of metal-organic frameworks (MOFs) by crystal downsizing is an important but often overlooked issue. Here, we report three different-sized flexible ZUL-520 MOFs (according to the crystal size from large to small, the three samples are, respectively, named ZUL-520-0, ZUL-520-1, and ZUL-520-2) with the same chemical structure for optimizing trace acetylene (C2H2) removal from acetylene/ethylene (C2H2/C2H4) mixture. The three differently sized activated ZUL-520 (denoted as ZUL-520a) exhibited almost identical C2H2 uptake of 4.8 mmol/g at 100 kPa, while the C2H2 uptake at 1 kPa increased with a downsizing crystal. The C2H2 uptake of activated ZUL-520-2 (denoted as ZUL-520-2a) at 1 kPa was ∼55% higher than that of activated ZUL-520-0 (denoted as ZUL-520-0a). The adsorption isotherms and adsorption kinetics validated that gas adsorptive separation is governed not only by adsorption thermodynamics but also by adsorption kinetics. In addition, all three different-sized ZUL-520a MOFs showed high C2H2/C2H4 selectivity. Grand canonical Monte Carlo (GCMC) simulations and dispersion-corrected density functional theory (DFT-D) computations illustrated a plausible mechanism of C2H2 adsorption in MOFs. Importantly, breakthrough experiments demonstrated that ZUL-520a can effectively separate the C2H2/C2H4 (1/99, v/v) mixture and the C2H4 productivity obtained by ZUL-520-2a was much higher than that by ZUL-520-0a. Our work may provide an easy but powerful strategy for upgrading the performance of gas adsorptive separation in MOFs.