H2 Capacity Research Articles

Catalysts for Liquid Organic Hydrogen Carriers (LOHCs): Efficient Storage and Transport for Renewable Energy.

Restructuring the current energy industry towards sustainability requires transitioning from carbon based to renewable energy sources, reducing CO2 emissions. Hydrogen, is considered a significant clean energy carrier. However, it faces challenges in transportation and storage due to its high reactivity, flammability, and low density under ambient conditions. Liquid organic hydrogen carriers offer a solution for storing hydrogen because they allow for the economical and practical storage of organic compounds in regular vessels through hydrogenation and dehydrogenation. This review evaluates several hydrogen technologies aimed at addressing the challenges associated with hydrogen transportation and its economic viablity. The discussion delves into exploring the catalysts and their activity in the context of catalysts' development. This review highlights the pivotal role of various catalyst materials in enhancing the hydrogenation and dehydrogenation activities of multiple LOHC systems, including benzene/cyclohexane, toluene/methylcyclohexane (MCH), N-ethylcarbazole (NEC)/dodecahydro-N-ethylcarbazole (H12-NEC), and dibenzyltoluene (DBT)/perhydrodibenzyltoluene (H18-DBT). By exploring the catalytic properties of noble metals, transition metals, and multimetallic catalysts, the review provides valuable insights into their design and optimization. Also, the discussion revolved around the implementation of a hydrogen economy on a global scale, with a particular focus on the plans pertaining to Saudi Arabia and the GCC (Gulf Cooperation Council) countries. The review lays out the challenges this technology will face, including the need to increase its H2 capacity, reduce energy consumption by providing solutions, and guarantee the thermal stability of the materials.

Spatial Confinement of Lithium Borohydride in Bimetallic CoNi-Doped Hollow Carbon Frameworks for Stable Hydrogen Storage.

While lithium borohydride is one of the most promising hydrogen storage materials due to its ultrahigh hydrogen storage density, high thermodynamic stability, kinetic barriers, and poor reversibility, it is far from being used in practical applications. Herein, we prepare a cubic hollow carbon dodecahedron uniformly modified with a bimetallic CoNi alloy (CoNi/NC) for preserving the stable catalytic effect of CoNi alloys toward reversible hydrogen storage. It is theoretically confirmed that bimetallic CoNi alloys effectively weaken the B-H bonds of LiBH4 by extending their average length to 1.33, 0.09 and 0.04 Å longer than that of LiBH4 and LiBH4 under metallic Co, respectively. More importantly, the alloying of Co with Ni avoids the reattachment of H from LiBH4 to the Co surface, which prevents LiBH4 from dehydrogenation for the formation of H2 on the Co surface, thus resulting in an ultralow hydrogen desorption energy of 0.1, 1.85 and 0.52 eV lower than that of LiBH4 and LiBH4 under metallic Co. Therefore, the onset and peak hydrogen desorption temperatures decrease to 130 and 355 °C, respectively, 170 and 97 °C lower than that of bulk LiBH4. More importantly, a reversible H2 capacity of 9.4 wt % is achieved even after 10 cycles.

Rational Design of 7‐Azaindole‐Based Robust Microporous Hydrogen‐Bonded Organic Framework for Gas Sorption

7‐Azaindole has been integrated as building block with complementary N‐H···N hydrogen bonding sites for the synthesis of a tetrahedral molecular tecton, namely tetra(α‐carbolin‐6‐yl)methane, TACM. The self‐assembly of this molecule results in a 3D hydrogen‐bonded organic framework (HOF). This supramolecular structure constitutes a crystalline microporous material with an extraordinary thermal and chemical robustness. Single crystal X‐ray diffraction reveals how the five‐fold catenation of diamonoid systems, stabilized by hydrogen bonds and π‐π interactions, form an interpenetrated network with monodimensional channels. The structural features of the crystalline material are also observed by transmission electron microscopy (TEM). Additionally, the microporosity of the activated TACM‐HOF is characterized by gas sorption (N2, CO2, CH4 and H2) experiments performed at different pressures. A selective adsorption is observed for CO2 uptake and TACM‐HOF also presents a good adsorption capacity for H2 among supramolecular organic frameworks.

Rational Design of 7-Azaindole-Based Robust Microporous Hydrogen-Bonded Organic Framework for Gas Sorption.

7-Azaindole has been integrated as building block with complementary N-H⋅⋅⋅N hydrogen bonding sites for the synthesis of a tetrahedral molecular tecton, namely tetra(α-carbolin-6-yl)methane, TACM. The self-assembly of this molecule results in a 3D hydrogen-bonded organic framework (HOF). This supramolecular structure constitutes a crystalline microporous material with an extraordinary thermal and chemical robustness. Single crystal X-ray diffraction reveals how the five-fold catenation of diamonoid systems, stabilized by hydrogen bonds and π-π interactions, form an interpenetrated network with monodimensional channels. The structural features of the crystalline material are also observed by transmission electron microscopy (TEM). Additionally, the microporosity of the activated TACM-HOF is characterized by gas sorption (N2, CO2, CH4 and H2) experiments performed at different pressures. A selective adsorption is observed for CO2 uptake and TACM-HOF also presents a good adsorption capacity for H2 among supramolecular organic frameworks.

Uncovering optimal carbon and boron nitride nanotube geometries for methane and hydrogen release

We screened 1651 carbon and boron nitride (BN) nanotubes to investigate methane release at 298 K and hydrogen release at 77 K through grand canonical ensemble Monte Carlo (GCMC) simulations. The effects of nanotube radius, density, and van der Waals spacing on the release quantities of these gases were explored. Our research shows that CH4 release in C(40,40) and BN(40,40) nanotubes reaches a high of 0.15 g/g, below the DOE's 0.5 g/g target. Similarly, the best nanotubes for volumetric release, C(21,9) and BN(18,18), peak at 175 cm³/cm³, below the DOE target of 330 cm³/cm³. This suggests that internal adsorption within isolated nanotubes is insufficient to meet DOE targets, highlighting the need for optimization of inter-tube van der Waals spacing. For H2, C(40,39) and BN(40,40) nanotubes are optimal for weight release, achieving up to 12.19% at a pressure of 8 MPa. This surpasses the 2025 DOE benchmark of 5.5 wt%. Meanwhile, C(28,7) and BN(24,24) nanotubes are most suitable for volumetric release. The C(28,7) nanotube, recommended for H2 storage, reaches a volumetric release quantity close to the DOE target of 0.04 kg/L at a van der Waals spacing of 1 nm. At pressures exceeding 2 MPa, the weight adsorption outside nanotubes accounts for 40–55% of the total, underscoring the pivotal role of extra-tube adsorption in gas storage capacity for both CH4 and H2. The results provide a foundation for the design of nanotube-based materials for efficient gas storage and release, with implications for clean energy applications.

Strong Swelling and Symmetrization in Siliceous Zeolites due to Hydrogen Insertion at High Pressure.

Hydrogen and helium saturate the 1D pore systems of the high-silica (Si/Al>30) zeolites Theta-One (TON), and Mobile-Twelve (MTW) at high pressure based on x-ray diffraction, Raman spectroscopy and Monte Carlo simulations. In TON, a strong 22 % volume increase occurs above 5 GPa with a transition from the collapsed P21 to a symmetrical, swelled Cmc21 form linked to an increase in H2 content from 12 H2/unit cell in the pores to 35 H2/unit cell in the pores and in the framework of the material. No transition and continuous collapse of TON is observed in helium indicating that the mechanism of H2 insertion is distinct from other fluids. The insertion of hydrogen in the larger pores of MTW results in a strong 11 % volume increase at 4.3 GPa with partial symmetrization followed by a second volume increase of 4.5 % at 7.5 GPa, corresponding to increases in hydrogen content from 43 to 67 and then to 93 H2/unit cell. Flexible 1D siliceous zeolites have a very high H2 capacity (1.5 and 1.7 H2/SiO2 unit for TON and MTW, respectively) due to H2 insertion in the pores and the framework, in contrast to other atoms and molecules, thereby providing a mechanism for strong swelling.

Strong Swelling and Symmetrization in Siliceous Zeolites due to Hydrogen Insertion at High Pressure

AbstractHydrogen and helium saturate the 1D pore systems of the high‐silica (Si/Al>30) zeolites Theta‐One (TON), and Mobile‐Twelve (MTW) at high pressure based on x‐ray diffraction, Raman spectroscopy and Monte Carlo simulations. In TON, a strong 22 % volume increase occurs above 5 GPa with a transition from the collapsed P21 to a symmetrical, swelled Cmc21 form linked to an increase in H2 content from 12 H2/unit cell in the pores to 35 H2/unit cell in the pores and in the framework of the material. No transition and continuous collapse of TON is observed in helium indicating that the mechanism of H2 insertion is distinct from other fluids. The insertion of hydrogen in the larger pores of MTW results in a strong 11 % volume increase at 4.3 GPa with partial symmetrization followed by a second volume increase of 4.5 % at 7.5 GPa, corresponding to increases in hydrogen content from 43 to 67 and then to 93 H2/unit cell. Flexible 1D siliceous zeolites have a very high H2 capacity (1.5 and 1.7 H2/SiO2 unit for TON and MTW, respectively) due to H2 insertion in the pores and the framework, in contrast to other atoms and molecules, thereby providing a mechanism for strong swelling.

Evaluation of parameters impacting grey H2 storage in coalbed methane formations

Injecting grey hydrogen into coalbed methane formations has the potential to transform coal into a geologically temporary “H2-Battery” and a permanent “CO2-sink”. This study aims to thoroughly evaluate crucial parameters-sorption, diffusion, and matrix swelling/shrinkage-that impact grey hydrogen injection in CH4-enriched coalbed formations. In terms of sorption capacity, CO2 exhibits the highest, followed by CH4 and then H2. Sorption data affirmed that anthracite coal has a certain degree of adsorption capacity for H2, with H2 demonstrating superior diffusive gas deliverability as indicated by its diffusion coefficient, which is approximately six times higher than that of CO2. These characteristic position coal as a promising candidate for temporary H2 storage and cleaning, optimizing injectivity and depletion efficiency. Interestingly, H2 adsorption induced matrix shrinkage in coal, in contrast to other strong sorption gases such as CH4 and CO2, which resulted in matrix swellings. Matrix deformations induced by H2–CO2 mixture (grey hydrogen) injection were conducted and quantified to evaluate grey hydrogen injection in future field trials. The results reveal that the majority of directional strains indicated that when the partial pressure of CO2 in the H2–CO2 mixture is equivalent to pure CO2 pressure, the latter case induces elevated swelling strains. This finding implicitly supports the hypothesis that H2–CO2 mixture injection causes less matrix swelling than pure CO2 injection at equivalent CO2 pressure. This work provides essential parameters to illustrate an enhanced synergism among hydrogen storage, carbon sequestration, and enhance coalbed methane recovery through grey hydrogen injection in coal formations.

Space confinement effect of carbon nanotube-alumina strip support on the Cu-Co catalysts for CO2 methanation

The present work reported the space confinement effect of carbon nanotube-alumina strip (CAS) support on the Cu-Co bimetallic catalyst or the single Cu, Co catalysts for the CO2 methanation. CAS, made by extrusion of nanotubes and Al-based sol and high temperature calcination, was a macroscopic support with sufficient mesopores and hydrophobic property. Cu-Co/CAS catalysts exhibited high catalytic activity for methanation of CO2 (H2/CO2=3:1), where CO2 conversion was 49.62% and CH4 selectivity was 95.98% at temperature as low as 250 ℃ and 1.5 MPa, and showed advantage significantly over those with the supports of individual nanotube or pure Alumina support. The comparison suggested the hydrophobicity of carbon nanotubes can effectively remove water from the metal active sites, enhancing the equilibrium of reverse water gas shift and CO methanation reactions, as compared to alumina support. Additionally, CAS support had a spatial confinement effect that increased the contact time of CO2 or intermediates with the active sites, compared with individual nanotube support. XPS and Raman spectroscopy validated the presence of oxygen vacancies of CAS, promoting the CO2 methanation. H2-TPR results, in combination with DFT calculations, confirmed that the CAS supports enabled the Cu-Co active phase by changing their electronic structures, to possess a strong adsorption activation capacity for H2 at low temperatures with high performance for CO2 methanation.

Constructing Single-Atom Active Sites Embedded in Hexagonal Boron Nitride for Adsorption and Sensing of Lithium Battery Thermal Runaway Gases.

The utilization and selectivity of single atoms have garnered significant attention among researchers. However, they are easy to agglomerate because of their high surface energy. To overcome this challenge, it is crucial to seek suitable carriers to anchor single metal atoms to achieve optimal performance. In this work, the structures of transition metal single atoms embedded in hexagonal boron nitride (MB2N2, M = Fe, Co, Ni, Cu, Zn) are constructed and used for the adsorption and sensing of lithium battery thermal runaway gases (H2, CO, CO2, CH4) through the DFT method. The adsorption behavior of MB2N2 was evaluated through the adsorption energy, sensitivity, and recovery time. The calculation results indicate that CoB2N2 exhibits strong adsorption capacity for both H2 and CO. The sensitivity of FeB2N2 toward CO is as high as 3.232 × 1016. Subsequently, the adsorption mechanism was studied through TDOS and PDOS, and the results showed that hybridization between orbitals enhanced the gas adsorption performance. This study presents novel approaches for designing single-atom carriers and developing MB2N2 sensors for detecting lithium battery thermal runaway gases.

Electrification and hydrogenation on a PV-battery-hydrogen energy flexible community for carbon–neutral transformation with transient aging and collaboration operation

Considering the distinct differences in intrinsic characteristics (e.g., energy efficiency, power density, and response time), the synergy operation of combined hydrogen (H2) and battery systems within the source-grid-load-storage framework offers a promising solution to stabilize intermittent renewable energy supply, mitigate grid power fluctuations, and enhance system independence. However, the idling power of the H2 system (fuel cell and electrolyzer) poses significant limitations on H2 charging/discharging from intermittent renewable power sources, thereby affecting overall system performance. However, the current literature provides little progress on how to effectively self-consume onsite renewable energy and supply the electricity demand with high energy/power density in a fast response. To address these challenges, this study proposes and applies the H2-battery compensation operation in the hybrid H2-battery energy storage system to mitigate the adverse effects of idling power during low-carbon transformations. Additionally, transient degradation models for the battery and fuel cell (FC) are integrated into the system to dynamically quantify real-time aging, thereby avoiding performance overestimation. Moreover, the study also includes a comparative analysis of the pre-estimation on the H2 tank pressure level, and a parametrical analysis of the HV number and battery capacity. Results show that, compared to the isolated H2 energy storage system, the H2-battery synergy operation reduces the grid demand shortage coverage ratio from 91.01% to 57.8%. Furthermore, the proposed H2-battery compensation operation effectively overcomes the limitations of idling power during power charging/discharging of the H2 system, resulting in an increase of H2 demand shortage coverage ratio from 8.9% to 17.29%, and the decrease in battery degradation ratio from 1.73% to 1.65%. Afterward, a novel indicator, degradation cost per kWh energy, is proposed to quantify the techno-economic performance of the combined battery and H2 system. According to the results, the techno-economic feasibility is dependent on the proportion of battery and H2 capacities, with the FC ranging from 0.49 to 1.15 CNY/kWh and the battery ranging from 0.82 to 0.91 CNY/kWh. The research results provide valuable frontier guidelines for the design and operation of multi-energy systems, as well as innovative energy-sharing strategies, to achieve sustainable and carbon–neutral transformation.

K-guided selective regulation mechanism for CO2 hydrogenation over Ni/CeO2 catalyst

Regulating the selectivity between CO and CH4 during CO2 hydrogenation is a challenging research topic. Previous research has indicated that potassium (K) modification can adjust the product selectivity by regulating the adsorption strength of formate/CO* intermediates. Going beyond the regulation mechanism described above, this study proposes a K-guided selectivity control method based on the regulation of key intermediates HCO*/H3CO* for Ni catalysts supported on reducible carrier CeO2. By incorporating K, the CO selectivity of CO2 hydrogenation shifts from around 25.4% for Ni/CeO2 to approximately 93.8% for Ni/CeO2-K. This can be attributed to K modification causes electron aggregation in the bonding regions of HCO* and H3CO* intermediates, thus enhancing their adsorption strength. Consequently, the reaction pathway from HCO*/H3CO* to CH4 is limited, favoring the decomposition of formates to CO products. Moreover, the addition of K leads to a moderate decrease in CO2 conversion from 55.2% to 48.6%, which still surpasses values reported in most other studies. This reduction is associated with a decline in reducible Ni species and oxygen vacancy concentration in Ni/CeO2-K. As a result, the adsorption capacity for CO2 and H2 reduces, ultimately reducing CO2 hydrogenation activity.

Prediction of hydrogen storage in metal-organic frameworks: A neural network based approach

Gas capture, sensing, and storage systems are all within the capabilities of metal–organic frameworks (MOFs). It is common practise to choose the MOF with the best adsorption property from a large database before running an adsorption calculation. High-throughput computational research is sometimes hampered by the expense of computing thermodynamic values, slowing the progress of MOFs for separations and storage applications. When trying to predict material properties, machine learning has recently emerged as a possible alternative to more conventional methods like experiments and simulations. The H2 capacities of 918,734 MOFs drawn from 19 databases were recently predicted using ML by Ahmed and Siegel (2021). Several ML methods were utilized, and the extremely randomised tree (ERT) model emerged as the most accurate predictor of hydrogen delivery capacity in terms of both gravimetric and volumetric quantities. Interestingly we have used deep learning model (Feed-forward neural network) as well as ERT model for the prediction of H2 deliverable capacities of a huge number of MOFs developed from the previous studies and got till date best results for predictions. To verify our model’s efficacy, we also performed Grand Canonical Monte Carlo (GCMC) simulations. We show our method by forecasting the hydrogen storage capacity of MOFs during a temperature and pressure swing from 100bar/77K to 5bar/160K.

Ethanolammonium chloride-glycerol deep eutectic solvents for efficient and reversible absorption of NH3 through multiple hydrogen-bond interaction

Efficiently separating NH3 from the exit gas of NH3 synthesis tower has significant economic and environmental benefits, such as improving the NH3 conversion rate and reducing pollution emission. In this study, a series of EtOHACl + Gly deep eutectic solvents (DESs) with numerous hydrogen-bond sites were synthesized. The findings suggest that the use of EtOHACl + Gly DESs can result in both exceptional NH3 absorption capacities and superior selectivities. EtOHACl + Gly (1:2) has the NH3 capacities of up to 12.39 mol/kg at 298.2 K and 105.5 kPa, while its N2 and H2 capacities are negligible. Additionally, the absorbed NH3 can be easily released by heating and reducing pressure, and the NH3 capacities remain stable after undergoing six cycles. The study also examined the interaction mechanism of EtOHACl + Gly DESs for the NH3 separation, utilizing spectral characterizations, quantum chemistry calculations and molecular dynamics simulations.

Topological Design of Unprecedented Metal-Organic Frameworks Featuring Multiple Anion Functionalities and Hierarchical Porosity for Benchmark Acetylene Separation.

Separation of acetylene (C2 H2 ) from carbon dioxide (CO2 ) or ethylene (C2 H4 ) is industrially important but still challenging so far. Herein, we developed two novel robust metal organic frameworks AlFSIX-Cu-TPBDA (ZNU-8) with znv topology and SIFSIX-Cu-TPBDA (ZNU-9) with wly topology for efficient capture of C2 H2 from CO2 and C2 H4 . Both ZNU-8 and ZNU-9 feature multiple anion functionalities and hierarchical porosity. Notably, ZNU-9 with more anionic binding sites and three distinct cages displays both an extremely large C2 H2 capacity (7.94 mmol/g) and a high C2 H2 /CO2 (10.3) or C2 H2 /C2 H4 (11.6) selectivity. The calculated capacity of C2 H2 per anion (4.94 mol/mol at 1 bar) is the highest among all the anion pillared metal organic frameworks. Theoretical calculation indicated that the strong cooperative hydrogen bonds exist between acetylene and the pillared SiF6 2- anions in the confined cavity, which is further confirmed by in situ IR spectra. The practical separation performance was explicitly demonstrated by dynamic breakthrough experiments with equimolar C2 H2 /CO2 mixtures and 1/99 C2 H2 /C2 H4 mixtures under various conditions with excellent recyclability and benchmark productivity of pure C2 H2 (5.13 mmol/g) or C2 H4 (48.57 mmol/g).

In situ formed MgTi2O4 from MgO improving the cycling stability of MgH2

Magnesium hydride (MgH2) is a potential candidate for hydrogen storage due to its high gravimetric and volumetric hydrogen capacities. However, high operating temperature and reversible H2 capacity attenuation inhibit its commercial application. To overcome these issues, we synthesized an N ion-doped Na2TiO3 (denoted as N-NaTiO) catalyst by reducing TiO2 with NaNH2. Experimental results show that the addition of 5 wt% N-NaTiO can lower the dehydrogenation peak temperature of MgH2 from 328 to 239 °C, and 6.0 wt% H2 is quickly released in ca. 4 min at 300 °C. In particular, the modified MgH2 exhibits a high reversible hydrogen capacity of 6.7 wt% which is equal to a retention of 94.4% after 250 cycles. Reaction mechanism investigations reveal that hydrogen insertion and removal during the ab/desorption processes are consistent with the reversible change of titanium valence states in the catalyst. In addition, it is observed that there is an irreversible evolution of MgO to MgTi2O4 at the interface between the catalyst and MgH2 during the cycling process, which is linked to the improvement of the ab/desorption kinetics and cycle stability.

Modulating the Interlayer Stacking of Covalent Organic Frameworks for Efficient Acetylene Separation.

Controllable modulation of the stacking modes of 2D (two-dimensional) materials can significantly influence their properties and functionalities but remains a formidable synthetic challenge. Here, an effective strategy is proposed to control the layer stacking of imide-linked 2D covalent organic frameworks (COFs) by altering the synthetic methods. Specifically, a modulator-assisted method can afford a COF with rare ABC stacking without the need for any additives, while solvothermal synthesis leads to AA stacking. The variation of interlayer stacking significantly influences their chemical and physical properties, including morphology, porosity, and gas adsorption performance. The resultant COF with ABC stacking shows much higher C2 H2 capacity and selectivity over CO2 and C2 H4 than the COF with AA stacking, which is not demonstrated in the COF field yet. Furthermore, the outstanding practical separation ability of ABC stacking COF is confirmed by breakthrough experiments of C2 H2 /CO2 (50/50, v/v) and C2 H2 /C2 H4 (1/99, v/v), which can selectively remove C2 H2 with good recyclability. This work provides a new direction to produce COFs with controllable interlayer stacking modes.

CO2, CH4, and H2 Adsorption Performance of the Metal–Organic Framework HKUST-1 by Modified Synthesis Strategies

High-pressure adsorption of CO2, H2, and CH4 has several applications, including CO2 capture, methane, and hydrogen storage. The performance ultimately depends on the adsorbent design. Herein, we report a comparative assessment of a Cu-metal–organic framework (MOF) (HKUST-1) by conventional hydrothermal synthesis and its modified analogues, HKUST-N with NH4OH and HKUST-Ca with Ca(NO3)2, for CO2, CH4, and H2 adsorption. The materials showed high CO2 (12 mol/Kg), CH4 (2.5–4 mol/Kg), and H2 (0.4–0.8 mol/Kg) capacities at 50 bar. Owing to different synthesis strategies, the differences in surface area, pore size distribution, morphology, and the presence of calcium species in HKUST-Ca considerably impacted CH4 and H2 adsorption, leading to considerable differences in selectivities for various gas mixtures. This work establishes a clear correlation of subtle modifications in synthesis strategies of the MOF HKUST-1 on its morphological characteristics and CO2, CH4, and H2 adsorption performance.

Overcoming the Trade-Off between C2 H2 Sorption and Separation Performance by Regulating Metal-Alkyne Chemical Interaction in Metal-Organic Frameworks.

Designing porous materials for C2 H2 purification and safe storage is essential research for industrial utilization. We emphatically regulate the metal-alkyne interaction of PdII and PtII on C2 H2 sorption and C2 H2 /CO2 separation in two isostructural NbO metal-organic frameworks (MOFs), Pd/Cu-PDA and Pt/Cu-PDA. The experimental investigations and systematic theoretical calculations reveal that PdII in Pd/Cu-PDA undergoes spontaneous chemical reaction with C2 H2 , leading to irreversible structural collapse and loss of C2 H2 /CO2 sorption and separation. Contrarily, PtII in Pt/Cu-PDA shows strong di-σ bond interaction with C2 H2 to form specific π-complexation, contributing to high C2 H2 capture (28.7 cm3 g-1 at 0.01 bar and 153 cm3 g-1 at 1 bar). The reusable Pt/Cu-PDA efficiently separates C2 H2 from C2 H2 /CO2 mixtures with satisfying selectivity and C2 H2 capacity (37 min g-1 ). This research provides valuable insight into designing high-performance MOFs for gas sorption and separation.

Concurrent Enhancement of Acetylene Uptake Capacity and Selectivity by Progressive Core Expansion and Extra-Framework Anions in Pore-Space-Partitioned Metal-Organic Frameworks.

A multi-stage core-expansion method is proposed here as one component of the integrative binding-site/extender/core-expansion (BEC) strategy. The conceptual deconstruction of the partitioning ligand into three editable parts draws our focus onto progressive core expansion and allows the optimization of both acetylene uptake and selectivity. The effectiveness of this strategy is shown through a family of eight cationic pore-partitioned materials containing three different partitioning ligands and various counter anions. The optimized structure, Co3 -cpt-tph-Cl (Hcpt=4-(p-carboxyphenyl)-1,2,4-triazole, H-tph=(2,5,8-tri-(4-pyridyl)-1,3,4,6,7,9-hexaazaphenalene) with the largest surface area and highest C2 H2 uptake capacity (200 cm3 /g at 298 K), also exhibits (desirably) the lowest CO2 uptake and hence the highest C2 H2 /CO2 selectivity. The successful boost in both C2 H2 capacity and IAST selectivity allows Co3 -cpt-tph-Cl to rank among the best crystalline porous materials, ionic MOFs in particular, for C2 H2 uptake and C2 H2 /CO2 experimental breakthrough separation.