CH4 Adsorption Research Articles

Properties and mechanisms of low concentration methane catalytic combustion in porous media supported with transition metal oxides

Low concentration methane (LCM) from coal mining is hardly utilized by combustion or oxidation due to its low concentration and fluctuation. Herein, a porous media catalytic combustion technology was presented to investigate the catalytic combustion properties of LCM in porous media by developing three porous media catalysts (Fe2O3/Al2O3, CuO/Al2O3 and Co3O4/Al2O3) supported with transition metal oxides (Fe2O3, CuO and Co3O4) as active components. While the catalytic combustion mechanism was proposed by density functional theory (DFT) calculations. The results indicated that Fe2O3/Al2O3 exhibited superior high-temperature catalytic activity and thermal stability, which was capable of broadening the limit equivalence ratio of CH4 stationary combustion to 0.46 with the CH4 conversion rate over 98 %. DFT calculations revealed that the Fe atoms on the (001) surface of Fe2O3 crystals were the active center during the catalytic process, causing the adsorption and dissociation of CH4 and O2 molecules. The lattice oxygen of Fe2O3 was engaged in the formation of CO and CO2 and the adsorbed oxygen from O2 molecules dissociation facilitated H2O generation, which heightened the conversion of CH4. This study provides a promising avenue for the high-efficiency and clean utilization of LCM.

Overcoming the kinetic and deactivation limitations of Ni catalyst by alloying it with Zn for the dry reforming of methane

Stimulated by the capacity of Zn to improve the adoption of CO2 and CH4, we doped a Ni-supported ZrO2 catalyst with Zn to enhance its performance and stability in the dry reforming of methane. We prepared a set of catalysts with different Ni:Zn:Zr proportions and conducted extensive ex situ and in situ characterizations to prove that a Ni–Zn alloy was formed at 750 °C under reductive conditions. Combining a tailored morphology of the alloy nanoparticles, strong metal–support (ZnO–ZrO2) interactions, and additional oxygen vacancies created by Zn inclusion resulted in an enhanced catalyst with 15% higher initial activity and higher stability for over 100 h on stream than Zn-free catalyst. Our experimental and modeling results demonstrated that the catalyst with adjusted Ni:Zn:Zr proportion improves the adsorption and reaction rates of CH4 and CO2 while extending its lifetime through enhanced coke precursor gasification compared to its Zn-free counterpart.

Molecular insights on influence of CO2 on CH4 adsorption and diffusion behaviour in coal under ultrasonic excitation

Decoupling the molecular structure from the pore structure is challenging under experimental conditions; this hinders the independent investigation of the effect of the changes in molecular structure on methane (CH4) transport. In this study, the molecular model of coal was reconstructed based on the test results of X-ray photoelectron spectroscopy (XPS) and 13C nuclear magnetic resonance (13C NMR). A grand canonical Monte Carlo (GCMC) based molecular dynamics (MD) simulation method was used to independently investigate the effect of CO2 on CH4 adsorption and diffusion behaviour in coal under changes in the molecular structure of coal after ultrasonic excitation. The experimental results show that, under ultrasonic excitation, the proportion of oxygen content in the coal increases and the oxygen-containing functional groups (carboxyl groups, ether bonds/hydroxyl groups) increase compared to the original coal. The simulation results show that the amount of CH4 adsorbed, the isosteric heat and the proportion of low-energy CH4 in the coal sample decrease after ultrasonic excitation for the same pore size. Furthermore, for the same pore size and CO2 partial pressure ratio, adsorption selectivity factor increases after ultrasonic treatment. Additionally, for the same pore size and the same CO2 partial pressure ratio, the interaction energy between CH4 and coal in the CH4–CO2–coal mixed system decreases and the density of high-energy CH4 increases after ultrasonic excitation; this leads to an increase in CH4 self-diffusion and transport diffusion coefficient. The presence of oxygen-containing functional groups causes a significant increase in the electrostatic potential difference between CO2 and coal as compared to that between CH4 and coal, which is the fundamental reason for the change in the effect of CO2 on the adsorption-diffusion behaviours of CH4. Our findings revealed the micro-mechanism of ultrasonic-assisted coalbed methane extraction and demonstrated the effectiveness of ultrasonic-CO2 collaborative technology.

Separation of C2H2/C2H4/C2H6 and C2H2/CO2 in a Nitrogen-Rich Copper-Based Microporous Metal-Organic Framework.

The purification of industrially valuable C2H2 and C2H4 from multicomponent mixtures represents a crucial process in the chemical industry. In this study, we present a copper-based metal-organic framework (L-py-Cu) built on a nitrogen-rich organic linker that is capable of separating C2H2/C2H4/C2H6 and C2H2/CO2 mixtures, therefore producing highly pure C2H4 and C2H2, respectively. L-py-Cu exhibits favorable adsorption of C2H2 and C2H6 over C2H4 and thus achieves one-step C2H4 purification from C2H2/C2H4/C2H6 ternary mixtures, as verified by multicomponent breakthrough measurements. In addition, it can also extract C2H2 from C2H2/CO2 binary mixtures.

A Microporous Zn(bdc)(ted)0.5 with Super High Ethane Uptake for Efficient Selective Adsorption and Separation of Light Hydrocarbons.

Separating light hydrocarbons (C2H6, C3H8, and C4H10) from CH4 is challenging but important for natural gas upgrading. A microporous metal-organic framework, Zn(bdc)(ted)0.5, based on terephthalic acid (bdc) and 1,4-diazabicyclo[2.2.2]octane (ted) ligands, is synthesized and characterized through various techniques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and porosity analysis. The adsorption isotherms of light hydrocarbons on the material are measured and the isosteric adsorption heats of CH4, C2H6, C3H8, and C4H10 are calculated. The prediction of C2-4/C1 adsorption selectivities is accomplished using ideal adsorbed solution theory (IAST). The results indicate that the material exhibits exceptional characteristics, including a Brunauer-Emmett-Teller (BET) surface area of 1904 m2/g and a pore volume of 0.73 cm3/g. Notably, the material demonstrates remarkable C2H6 adsorption capacities (4.9 mmol/g), while CH4 uptake remains minimal at 0.4 mmol/g at 298 K and 100 kPa. These findings surpass those of most reported MOFs, highlighting the material's outstanding performance. The isosteric adsorption heats of C2H6, C3H8, and C4H10 on the Zn(bdc)(ted)0.5 are higher than CH4, suggesting a stronger interaction between C2H6, C3H8, and C4H10 molecules and Zn(bdc)(ted)0.5. The molecular simulation reveals that Zn(bdc)(ted)0.5 prefers to adsorb hydrocarbon molecules with richer C-H bonds and larger polarizability, which results in a stronger dispersion force generated by an adsorbent-adsorbate induced polarization effect. Therefore, the selectivity of C4H10/CH4 is up to 180 at 100 kPa, C3H8/CH4 selectivity is 67, and the selectivity of C2H6/CH4 is 13, showing a great potential for separating C2-4 over methane.

A theoretical study on the separation of CO2/CH4 through MFI zeolite

The separation of carbon dioxide (CO2) and methane (CH4) is important in addressing global warming and energy shortages. Porous materials play a large role, of which MFI zeolite has received much attention. To better analyse mechanisms or guide experiments, the adsorption and diffusion properties of CO2 and CH4 in MFI zeolite have been studied by Monte Carlo and molecular dynamics simulations. Due to stronger interactions, the loading of pure CO2 is significantly higher than that of CH4. For mixtures (biogas or natural gas), CO2 dominates in competitive adsorption. Lower temperatures and higher pressures correspond to higher adsorption selectivity. In addition, the self-diffusion coefficients of guest molecules in MFI zeolite were also calculated. The diffusion performance of pure CH4 is superior to CO2 under the same conditions. And their self-diffusion coefficient increases with increasing temperature and decreasing load. For mixed components, CO2 greatly limits the diffusion of CH4.

Ag-doped Monolayer and Bilayer Graphene for the Gas Sensor and Purifier of Industrial Oils

Graphene sensors have high sensitivity and selectivity and are commonly used to detect and clean oilbreakdownresulting gas contaminants. Silver impurities on Graphene sheet vacancywere simulated for Methane interaction with vacant Graphene layers, with and without silver impurities, based on density functional theory with Quantum ESPRESSO.PBEexchange–correlation function withGGAfunction and vdW-DF corrections were used. Analyzing adsorption energies revealed theeffects of the additives on Graphene, andshowedGraphene with silver impuritieswasa good option. Analyzes of methane(CH4/MVG,CH4/BVG,CH4/MVG_Ag,andCH4/BVG_Ag)show that adsorption strengths of the structures were the relationship MVG_Ag > BVG > MVG > BVG_Ag. AddingAgimpurity to the foil greatly increases the CH4 adsorption strength of MVG_Ag and decreases the adsorption strength of BVG_Ag. Due to CH4′s symmetry, orientation relative to Graphene makes no difference as it interacts with carbon atoms from any side.

Simulation of the influences of different minerals contained in acidified coal on CH4 adsorption

To reveal the microscopic mechanism of CH4 adsorption by the main minerals in acidified coal, the depth of acid ion intrusion, the amount of CH4 adsorbed using isothermal adsorption experiments, and heat of adsorption were simulated by Grand Canonical Monte Carlo (GCMC) method for the composite molecular model composed of kaolinite, calcite, dolomite, and quartz with coal, respectively. The results show that the depth of acid ion intrusion directly affects the amount of methane adsorption. At pressures of 0–8 MPa, the F− intrusion depth directly affected the CH4 adsorption of the composite model of coal–kaolinite (quartz); the depths of Cl− and CH3COO− intrusion directly affected the methane adsorption of the composite model of coal–dolomite; the mixed acid containing Cl− and CH3COO− had the greatest effect on promoting methane adsorption. When acidifying the coal–calcite (quartz) compound structure, Cl− and CH3COO− increased the depth of F− intrusion, and the increase caused by CH3COO− was greater than that of Cl−. After acidification of the coal–calcite composite, the relationship between methane adsorption and heat of adsorption gradually changed from negative to positive with the increase of the hydrofluoric acid (HF) concentration; after acidification of composites of coal and other minerals, CH4 adsorption and heat of adsorption were positively correlated. The amount of CH4 adsorption after coal–kaolinite and coal–quartz acidification exceeded that of coal–calcite and coal–dolomite, mainly because the acidification of dolomite and calcite would generate CO2 to compete with CH4 for adsorption.

Successively separating C3H6 and C2H4 from C2H4/C2H6/C3H6/C3H8 mixture in tandem fixed beds involving two zeolites LTA well-regulated via low transition-metal doping

There is great interest in adsorptive separation of light olefins from alkanes with the same carbon number. However, previous investigations mainly focused on binary olefin/alkane mixtures or always produced mixed olefin from multiple components. Adsorptive separation of single-component olefins from mixtures containing multiple olefins is of practical importance but still a big challenge in industry. Present work provides an approach to the successive separation of C3H6 and C2H4 from a mixture of C2H4/C2H6/C3H6/C3H8 using tandem twin fixed beds filled with two well-regulated zeolites LTA. The adsorbents of Ni-5A and Ag/Cd-4A were post-synthesized via low transition-metal doping into zeolites LTA and employed to separate the C3H6 and C2H4 from the quaternary mixture. The Ni-5A attains a C3H6 uptake of 2.25 mmol/g and a C3H6/C2H4 Henry selectivity of 10.4, while the Ag/Cd-4A exhibits a C2H4 adsorption capacity of 3 mmol/g and a C2H4/C2H6 Henry selectivity of 1015.5. Furthermore, the molecule sieving of C2H4 is mainly determined by the micropore size of adsorbent, and the selective adsorption of C3H6 over C2H4 is largely attributed to the strong guest – host interactions with the metal sites. In addition, both the Ag/Cd-4A and Ni-5A adsorption beds can be well desorbed via CO2 purging. The DFT calculations reveal the molecular deformation of C2H4 and C3H6 during passing through the 8MR of Ag/Cd-4A and the competitive adsorption affinity of Ni-5A towards C3H6. The present process of tandem fixed beds coupled with well-regulated zeolite adsorbents provide an efficient strategy for the adsorptive separation of the mixtures of olefins and alkanes.

Carboxymethyl cellulose/polyvinyl alcohol composite aerogel supported beta molecular sieve for CH4 adsorption and storage

Biomass aerogel is attractive in various applications due to their renewable, biodegradable and eco-friendly advantages. Herein, a novel beta molecular sieve/carboxymethyl cellulose/polyvinyl alcohol composite aerogel (beta/CP) is prepared by direct mixing and directional freeze-drying as an efficient gas adsorbent with hierarchical porosity. The beta molecular sieve is uniformly dispersed in the three-dimensional skeleton of the aerogel. By adjusting the loading mass of the beta molecular sieve to constitute a reasonable porosity and pore size distribution, the synergistic effect between pore structures of different scales improves the adsorption performance. The experiment results of beta/CP-4 show that the CH4 adsorption capacity can reach 60.33 cm3/g at 298 K and 100 bar, which is almost the same as that of the pure beta molecular sieve (62.09 cm3/g). The strong interaction between the aerogel and it prevents the molecular sieve agglomeration, improves the pore utilization, and also reduces the cost of using molecular sieve adsorbent. The above results indicate that the composite has good potential for application in the field of CH4 storage.

Highly Efficient Solar-driven Dry Reforming of Methane on a Rh/LaNiO3 Catalyst through a Light-induced Metal-to-metal Charge Transfer Process.

As an energy-saving and green method, solar-driven dry reforming of methane (DRM) is expected to introduce new activation processes and prevent sintering and coking of the catalysts. However, it still lacks an efficient way to the coordinate regulation of activation of reactants and lattice oxygen migration. In this work, Rh/LaNiO3 is designed as a highly efficient photothermal catalyst for solar-driven DRM, which performs production rates of 452.3mmol h-1 gRh -1 for H2 and 527.6mmol h-1 gRh -1 for CO2 under a light intensity of 1.5W cm-2 , with an excellent stability. Moreover, a remarkable light-to-chemical energy efficiency (LTCEE) of 10.72% is achieved under a light intensity of 3.5W cm-2 . The characterizations of surface electronic and chemical properties and theoretical analysis demonstrate that strong adsorption for CH4 and CO2 , light-induced metal-to-metal charge transfer (MMCT) process and high oxygen mobility together bring Rh/LaNiO3 excellent performance for solar-driven DRM. This article is protected by copyright. All rights reserved.

Bioinspired microenvironment modulation of metal–organic framework-based catalysts for selective methane oxidation

Inspiration from natural enzymes enabling creationary catalyst design is appealing yet remains extremely challenging for selective methane (CH4) oxidation. This study presents the construction of a biomimetic catalyst platform for CH4 oxidation, which is constructed by incorporating Fe-porphyrin into a robust metal–organic framework, UiO-66, furnished with saturated monocarboxylic fatty acid bearing different long alkyl chains. The catalysts demonstrate the high efficiency in the CH4 to methanol (CH3OH) conversion at 50 °C. Moreover, the selectivity to CH3OH can be effectively regulated and promoted through a fine-tuned microenvironment by hydrophobic modification around the Fe-porphyrin. The long-chain fatty acids anchored on the Zr-oxo cluster of UiO-66 can not only tune the electronic state of the Fe sites to improve CH4 adsorption, but also restrict the amount of H2O2 around the Fe sites to reduce the overoxidation. This behavior resembles the microenvironment regulation in methane monooxygenase, resulting in high CH3OH selectivity.

Oxygen effect on the synthesis of vinyl acetate on Pd (100) and Pd/Au (100) surfaces: A periodic DFT study

Vinyl acetate is mainly produced by oxidative acetoxylation of ethylene over the Pd/Au bimetallic heterogeneous catalyst. This process requires the involvement of oxygen, but the role of oxygen has not been well studied. The oxygen effect on the synthesis of vinyl acetate is of considerable economic benefit, as the process conditions can be better optimized. In this study, the O2 adsorption and dissociation on the Pd (100) and Pd/Au (100) surfaces, the effect of the co-adsorbed O atom on the C2H4, CH3COOH and CH3COO adsorptions, and the reaction mechanism have been investigated using ab initio density functional theory (DFT) method. The calculated results suggest that the O adatoms are detrimental to the adsorption of C2H4 and CH3COO, but favorable for CH3COOH. For the reaction, the O adatoms reduce the energy barrier of CH3COOH dehydrogenation and VA formation, and increase the reaction enthalpy (more exothermic). This study provides further mechanistic insight into VA synthesis on the Pd-based catalysts.

High-capacity dynamic exclusion for highly efficient dilute C2H2 separation from CO2 and multicomponent mixture in robust ultramicroporous MOF by topology regulation

Acquiring high C2H2 adsorption capacity and effectively separating it from the most difficult-to-separate byproduct CO2 in a dilute state are crucial for obtaining high productivity/purity monomer for polymers. Here, we address this challenge through topology regulation of fluorinated ultramicroporous metal–organic framework, producing a new hydrolytically stable adsorbent, ZUL-500. Uncovered by X-ray diffraction and modeling, a more favorable spatial distribution of GeF62- anions for C2H2 recognition is realized in sql topological ZUL-500 compare to ZU-32 with the same anion and metal node but pcu topology, offering remarkably increased C2H2 affinity and amplified C2H2/CO2 affinity difference that affords a dynamic exclusion of CO2 but excellent C2H2 adsorption in fixed-bed separation even for industrial-related mixtures (up to 8 components). Excellent values were simultaneously obtained for C2H2 uptake capacity, C2H2/CO2 separation factor and C2H2 productivity, coupled with good mass transfer and recyclability, providing exceptional productivity (2.92 ∼ 3.48 mmol g−1) of high purity (≥99.6%) C2H2 from mixtures.

The Enhancement of CO2 and CH4 Capture on Activated Carbon with Different Degrees of Burn-Off and Surface Chemistry.

Activated carbon derived from longan seeds in our laboratory and commercial activated carbon are used to investigate the adsorption of methane (CH4) and carbon dioxide (CO2). The adsorption capacity for activated carbon from longan seeds is greater than commercial activated carbon due to the greater BET area and micropore volume. Increasing the degree of burn-off can enhance the adsorption of CO2 at 273 K from 4 mmol/g to 4.2 and 4.8 mmol/g at 1000 mbar without burn-off, to 19 and 26% with burn-off, respectively. This is because an increase in the degree of burn-off increases the surface chemistry or concentration of functional groups. In the investigation of the effect of the hydroxyl group on the adsorption of CO2 and CH4 at 273 K, it is found that the maximum adsorption capacity of CO2 at 5000 mbar is about 6.4 and 8 mmol/g for cases without and with hydroxyl groups contained on the carbon surfaces. The opposite behavior can be observed in the case of methane, this is due to the stronger electrostatic interaction between the hydroxyl group and carbon dioxide. The simulation results obtained from a Monte Carlo simulation method can be used to support the mechanism in this investigation. Iron oxide is added on carbon surfaces with different concentrations to reveal the effects of ferric compounds on the adsorption of CO2. Iron at a concentration of about 1% on the surface can improve the adsorption capacity. However, excessive amounts of iron led to a limited adsorption capacity. The simulation result shows similar findings to the experimental data. The findings of this study will contribute to the progress of gas separation technologies, paving the way for long-term solutions to climate change and greenhouse gas emissions.

Activation of Dinitrogen Promoted by Adsorption of C6H6 on Fe2VC- Cluster Anions.

The introduction of organic ligands is one of the effective strategies to improve the stability and reactivity of metal clusters. Herein, the enhanced reactivity of benzene-ligated cluster anions Fe2VC(C6H6)- with respect to naked Fe2VC- is identified. Structural characterization suggests that C6H6 is molecularly bound to the dual metal site in Fe2VC(C6H6)-. Mechanistic details reveal that the cleavage of N≡N is feasible in Fe2VC(C6H6)-/N2 but hindered by an overall positive barrier in the Fe2VC-/N2 system. Further analysis discloses that the ligated C6H6 regulates the compositions and energy levels of the active orbitals of the metal clusters. More importantly, C6H6 serves as an electron reservoir for the reduction of N2 to lower the crucial energy barrier of N≡N splitting. This work demonstrates that the flexibility of C6H6 in terms of withdrawing and donating electrons is crucial to regulating the electronic structures of the metal cluster and enhancing the reactivity.

Adsorption performance and gas sensing of the Ru atomic catalyst on GaN sheets to transformer oil dissolved gases

The Ru atomic catalyst-doped GaN (Ru-GaN) model was established by density functional theory (DFT), and the adsorption models of transformer oil dissolved gas (CO, H2, CH4, C2H2, C2H4 and C2H6) by a Ru-GaN monolayer were optimised. From the adsorption energy, differential charge density, electron state density, molecular orbital and desorption properties, the modification mechanism of Ru-GaN and the gas-sensitive response mechanism of Ru-GaN to CO, H2, CH4, C2H2, C2H4 and C2H6 were systematically studied. The introduction of metal Ru increases the defect state of GaN to provide the active site for the adsorption of gas molecules and reduces the adsorption barrier of GaN to gas molecules. The results show that Ru metal-doped GaN can adsorb CO, C2H2 and C2H4 by chemisorption, with Eads of −2.068 eV, −2.422 eV and −1.877 eV and Qt of −0.1696 e, −0.0671 e, −0.1222 e. In addition, charge redistribution leads to changes in the density of states, molecular orbitals and the conductivity of CO, C2H2 and C2H4 adsorption systems, indicating excellent gas sensitivity to the three gases. The desorption time further verified that Ru-GaN is an ideal CO and C2H2 gas scavenger and a recyclable material for C2H4 gas sensors.

Investigating the selective adsorption of CO2 by MIL-101(Cr)-NH2 and modeling the equilibrium data using a new three-parameter isotherm

Compared to MIL-101(Fe)-NH2, MIL-101(Cr)-NH2 has considerably higher adsorption of CO2. On the other hand, the adsorption of CH4 and N2 by MIL-101(Cr)-NH2 is lower than the adsorption of these gases by MIL-101(Fe)-NH2 leading to a higher selectivity of CO2 to CH4 and N2 for MIL-101(Cr)-NH2. The chemisorption mechanism is more influential in higher temperatures and pressure, which can be attributed to the performance of amines which can adsorb more CO2 at higher temperatures and pressure. The isosteric heat of CO2 adsorption on MIL-101(Cr)-NH2 was estimated equal to − 31 kJ mol-1.MIL-101(Cr)-NH2 was synthesized and characterized by the BET, XRD, FESEM, TGA, and DTA methods. The BET surface area of the synthesized MOF was achieved equal to 1768 m2 g-1. The adsorption capacity of pure CO2, CH4, and N2 was estimated using the volumetric method. A new three-parameter equation was presented to model the experimental adsorption data including both types I and II isotherm shapes. Using the Ideal Adsorbed Solution Theory (IAST), the selectivity of CO2 to CH4 at high pressure, and CO2 to N2 at lower pressures was estimated equal to 4.1 and 4.7, respectively. In addition to 25 °C, the adsorption tests were performed at 18 and 30 °C to estimate the adsorption heat of CO2 on MIL-101(Cr)-NH2 achieved equal to − 31 kJ mol-1. The adsorption isotherm of CO2 at 25 and 30 °C have been almost identical showing the role of the chemisorption mechanism of CO2 by the amine functional group, especially at higher temperatures and pressures. Furthermore, the resistance of synthesized MOF to water was investigated by putting it in contact with water for 24 h. The result showed that MIL-101(Cr)-NH2 can be classified as thermodynamically stable to water.

Fine-tuning channel structure and surface chemistry of stable bismuth-organic frameworks for efficient C2H4 purification through reversely trapping CO2 and C2H2

One-step C2H4 purification from ternary C2H4/C2H2/CO2 mixtures is of prime importance but challenging in chemical industries, owing to similar physicochemical properties of the three gases. Herein, we investigated the potential of ultramicroporous Bi-MOFs modified with –CHO, –COOH, –NO2, -F, -Cl, -Br, and -I for C2H4 purification. These MOFs featured good thermodynamic and thermal stability and exhibited precise regulation of channel sizes and surface structures/electronegativity. Their separation performances for CO2/C2H4, C2H2/C2H4, and CO2/C2H2 were theoretically investigated by grand canonical Monte Carlo, density functional theory, and transient breakthrough simulations. Results showed that introducing –CHO/–COOH/–NO2 enlarged the difference of adsorption uptakes between CO2, C2H2, and C2H4 favoring efficient separation of corresponding mixtures, in which Bi-MOF-CHO showed the highest selectivity for CO2/C2H4, C2H2/C2H4, and CO2/C2H2, with values of 58.6 (64.5), 11.8 (11.5), and 7.7 (21.5) under 50/50 (1/99) at ambient conditions. The enhanced separation performance is attributed to the synergism of pore size limitation, fine-tuned surface structure, and high surface electronegativity, resulting in special CO2 recognition, moderate enhancement for C2H2, but negligible influence on C2H4 adsorption. This work provides an effective strategy to design high-performance adsorbents for one-step C2H4 purification from ternary C2H4/C2H2/CO2 mixtures.

Robust Hydrogen-Bonded Organic Framework with Four-Fold Interpenetration for Adsorptive Separation of C2H6/C2H4 and Xe/Kr.

Hydrogen-bonded organic frameworks (HOFs) are an emerging class of porous materials that hold promise for the adsorptive separation of industrially relevant gas mixtures. However, developing HOFs with high thermal stability and resistance to water remains a daunting challenge. We report here a microporous HOF (HIAM-103) assembled from a hexacarboxylate linker (2,4,6-trimethylbenzene-1,3,5-triylisophthalic acid, H6TMBTI). The compound crystallizes in the trigonal crystal system, and its structure is a four-fold interpenetrated network. Upon thermal activation, the single crystals remain intact, allowing for precise determination of the activated structure. HIAM-103 exhibits remarkable thermal and hydrothermal stability. Its microporous channels demonstrate selective adsorption of C2H6 over C2H4 and Xe over Kr, and its separation capability toward mixed gases has been validated by column breakthrough experiments under dry and humid conditions. The preferential gas adsorption sites and separation mechanisms have been uncovered through DFT analysis, which suggests that the methyl group decorated 1D channels are the primary reason for the selective adsorption.