Column Breakthrough Experiments Research Articles

Post-modified porous aromatic frameworks for carbon dioxide capture

A new method was developed for post-modification of porous aromatic framework-1 (PAF-1) with chloride and then amine groups confirmed by different characterizations such as nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). Compared to PAF-1, the amine-functionalized PAF-1 (PAF-1-NH2) exhibits a 50% improvement in carbon dioxide (CO2) adsorption capacity reaching 42 cm3·g-1 at room temperature and 1 bar, and the uptakes under CO2 concentration in air (4 kPa) and flue gas (150 kPa) also greatly increase. The column breakthrough experiments showed that PAF-1-NH2 can separate CO2 from a simulated flue gas of CO2/N2 (15:85, v/v) indicating its potential applications in post-combustion systems.

High-Pressure Molecular Sieving of High-Humidity C2H4/C2H6 Mixture by a Hydrophobic Flexible Metal-Organic Framework.

Molecular sieving is an ideal separation mechanism, but controlling pore size, restricting framework flexibility, and avoiding strong adsorption are all very challenging. Here, we report a flexible adsorbent showing molecular sieving at ambient temperature and high pressure, even under high humidity. While typical guest-induced transformations are observed, a high transition pressure of 16.6 atm is observed for C2H4 at 298 K because of very weak C2H4 adsorption (~16 kJ mol-1). Also, C2H6 is completely excluded below the pore-opening pressure of 7.7 atm, giving single-component selectivity of ca. 300. Quantitative high-pressure column breakthrough experiments using 1:1 C2H4/C2H6 mixture at 10 atm as input confirms molecular sieving with C2H4 adsorption of 0.73 mmol g-1 or 32 cm3(STP) cm-3 and negligible C2H6 adsorption of 0.001(2) mmol g-1, and the adsorbent can be completely regenerated by inert gas purging. Furthermore, it is highly hydrophobic with negligible water adsorption, and the C2H4/C2H6 separation performance is unaffected at high humidity.

Biochar from co-pyrolysis of biological sludge and woody waste followed by chemical and thermal activation: end-of-waste procedure for sludge management and biochar sorption efficiency for anionic and cationic dyes

Nine biochars were produced by co-pyrolysis of sawdust and biological sludge following the “design of experiment” approach. Two kinds of sludge (both deriving from the treatment of mixed industrial-municipal wastewater) and two types of woody waste were selected as categorical predicting variables, while contact time, pyrolysis temperature, and sludge percentage were used as quantitative variables. Biochars were analysed for their product characteristics and environmental compatibility based on the European Standards (EN 12915–1:2009) for materials intended for water treatment (i.e. ash content, water leachable polycyclic aromatic hydrocarbons (PAHs) and elements), as well as for specific surface area (SSA), using them as response variables of a multivariate partial least square multiple regression, whose results provided interesting insights on the relationships between pyrolysis conditions and biochar characteristics. Biochars produced with sludge and/or providing the highest SSA values (258–370 m2 g−1) were selected to undergo a sustainable chemical treatment using a by-product of the gasification of woody biomass, complying in all cases with European Standards and achieving therefore the end-of-waste status for sewage sludge. The biochar deriving from the highest percentage of sludge (30% by weight) and with the highest SSA (390 m2 g−1) was thermally activated achieving SSA of 460 m2 g−1 and then tested for the sorption of direct yellow 50 and methylene blue in ultrapure water and real wastewater, compared to a commercial activated carbon (AC). The biochar showed Langmuir sorption maxima (Qm) 2–9 times lower than AC, thus highlighting promising sorption performances. Qm for methylene blue in wastewater (28 mg‧g−1) was confirmed by column breakthrough experiments.

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.

Simple synthesis of acyl coupling conjugated microporous polymers monolithic material for synergistic capture of PM and CO2 in flue gas and process simulation

Adsorption and separation technologies based on physical adsorbents have the advantages of simple operation, low heat of adsorption and easy regeneration. They have received much attention for the capture of CO2 and PM from flue gases. However, the inherent “trade-off” between adsorption capacity and adsorption selectivity, as well as the high gas permeation resistance after powder processing and shaping, severely limit the prospects for industrial applications. Here, acyl functional groups were strategically introduced into polymer frameworks to successfully synthesize monolithic adsorbents (AC-CMPs) with a hierarchical pore structure for PM capture and CO2/N2 selective adsorption. The three-dimensional network structure composed of aligned hollow nanotubes effectively enhances the dispersion and mass transfer of gas flow per unit volume. Based on the porous media, multiphase flow model and discrete phase model, the gas flow process of PM trapped by AC-CMPs was simulated using Fluent. The simulation dynamically revealed the relationship between permeability resistance and filtration efficiency. The highly delocalized π-π conjugated porous skeleton linked by continuous covalent bonds endowed AC-CMPs with good stability, which prevented them from degrading in humid and high-temperature environments, thus keeping the adsorption capacity unchanged. The high polarity environment generated by the open oxygen atoms within the AC-CMPs framework, along with a high micro/mesopore ratio, enable it to achieve a CO2 adsorption capacity of 2.07 mmol/g at 273 K and 1 bar. Ideal adsorption solution theory calculations (IAST) and CO2/N2 column breakthrough experiments confirmed the excellent CO2 selectivity of AC-CMPs under realistic carbon capture conditions.

Architecture dependent transport behavior of iron (0) entrapped biodegradable polymeric particles for groundwater remediation

Polylactic acid based spherical particles with three architectural variations (Isotropic (P1), Semi porous (P2), and Janus (P3)) were employed to encapsulate zero valent iron nanoparticles (ZVINPs), and their performance was extensively evaluated in our previous studies. However, little was known about their transportability through saturated porous media of varying grain size kept under varying ionic strength. In this particular study, we aimed to investigate the architectural effect of polymeric particles (P1–P3) on their mobility through the sand column of varying grain size in presence of mono, di, and tri-valent ions of varying concentrations (25–200 mM (millimoles)). As per column breakthrough experiments (BTCs) using various types of sands, amphiphilic Janus type (P3) particles exhibited the maximum transportability among all the tested particles, irrespective of the nature of the sand. Owing to the narrower travel path, sands with lower porosity (31%) delayed the plateau by shifting it to a higher pore volume with a minimum retention of iron (C/Co: 0.94 for P3) in the column. The impact of mono (Na+, K+), di (Ca2+, Mg2+), and trivalent (Al3+) ions on their transportability was progressively increased from P3 to P1, especially at higher ionic concentrations (200 mM), with P3 being the most mobile particles (C/Co:0.54 for Al3+). Among all the ions, Al3+ exhibited maximum hindrance to their mobility through the sand column. This could be due to their strong charge screening effect coupled with cation bridging complex formation with moving particles. Experimental results obtained from BTCs were found to be well-fitted with a theoretical model based on advection-dispersion equation, showing minimum retention for P3 particles. Overall, it can be inferred that encapsulation of ZVINPs inside Janus particles (P3) with a right balance of amphiphilicity and highly negative surface charge would be required to achieve considerable transportability through sand aquifers to target contaminants in polluted groundwater existing under harsh conditions (high ionic concentrations).

Shaping of MIL-53-Al and MIL-101 MOF for CO2/CH4, CO2/N2 and CH4/N2 separation

Metal-organic frameworks (MOF) are promising materials for gas storage and separation. The formulation and shaping of MOFs in mechanically stable bead forms is an essential requirement for their practical application as an adsorbent for gas and liquid mixture separations. In this work, MIL-53-Al and MIL-101 MOF beads are synthesized using sodium alginate as a binder, and calcium chloride as a gelling agent. The synthesized MIL-53-Al and MIL-101 MOF beads are characterized by powder X-ray diffraction (PXRD), BET surface area, porosity analysis from N2 uptake data at 77 K, FTIR, TGA, and scanning electron microscopy (SEM). The isothermal equilibrium adsorption uptake of CH4 and N2 gases is measured up to 10 bar pressure while the CO2 equilibrium uptake is measured up to 1 bar at 298 and 313 K respectively. The isotherm data of all adsorbates are fitted in Dual Site Langmuir (DSL) isotherm equations. The adsorption selectivity for CH4/N2, CO2/CH4, and CO2/N2 binary systems are predicted using the Ideal Adsorbed Solution Theory (IAST) method. The dynamic column breakthrough experiments are carried out on MIL-53-Al beads for CH4/N2 (30:70 and 50:50 v/v), CO2/CH4 (45:55 v/v) and CO2/N2 (15: 85 v/v) feed mixtures. The IAST selectivity and breakthrough time obtained under the same superficial velocity, pressure, and temperature conditions follow the order CO2/N2 > CO2 /CH4 > CH4/N2. The MIL-53-Al beads show higher CH4/N2, CO2/CH4, and CO2/N2 selectivity for the targeted mixtures than MIL-101 beads.

Breakthrough analysis of the CO2/CH4 separation on electrospun carbon nanofibers

AbstractThe removal of the main impurity CO2 is a crucial step in biogas upgrading. In this work, the separation of CO2 from CH4 on electrospun polyacrylonitrile-based carbon nanofibers (CNFs) is investigated using breakthrough experiments. The CNFs are prepared at various carbonization temperatures ranging from 600 to 900 °C and feature a tailorable pore size that decreases at higher carbonization temperatures. The adsorption properties of the different CNFs are studied measuring pure component isotherms as well as column breakthrough experiments. Adsorption kinetics are discussed using a linear driving force approach to model the breakthrough experiment and obtain the adsorption rate constant. Moreover, different approaches to determine the selectivity of the competitive CO2/CH4 adsorption are applied and discussed in detail. The results clearly prove that a size exclusion effect governs the adsorption selectivity on the CNFs. While CH4 cannot adsorb in the pores of CNFs prepared at 800 °C or above, the smaller CO2 is only excluded from the pores of CNFs prepared at 900 °C. For CNFs carbonized in the range from 600 to 750 °C, values of the CO2/CH4 selectivity of 11–14 are obtained. On the CNFs prepared at 800 °C the CH4 adsorption is severely hindered, leading to a reduced adsorbed amount of CH4 and consequently to an improved CO2/CH4 selectivity of 40. Furthermore, owing to the shrinking pores, the adsorption rates of CH4 and CO2 decrease with higher carbonization temperature.

Linker-Guided Growth of Single-Crystal Covalent Organic Frameworks.

The core features of covalent organic frameworks (COFs) are crystallinity and porosity. However, the synthesis of single-crystal COFs with monomers of diverse reactivity and adjustment of their pore structures remain challenging. Here, we show that linkers that can react with a node to form single-crystal COFs can guide other linkers that form either COFs or amorphous polymers with the node to gain single-crystal COFs with mixed components, which are homogeneous on the unit cell scale with controlled ratios. With the linker-guided crystal growth method, we created nine types of single-crystal COFs with up to nine different components, which are more complex than any known crystal. The structure of the crystal adapted approximately to that of the main component, and its pore volume could be expanded up to 8.8%. Different components lead to complex and diverse pore structures and offer the possibilities to gain positive synergies, as exemplified by a bicomponent COF with 2200 and 733% SO2 uptake capacity of that of the two pure-component counterparts at 298 K and 0.002 bar. The selectivity for separation of SO2/CO2 ranges from 1230 to 4247 for flue gas based on ideal adsorbed solution theory, recording porous crystals. The bicomponent COF also exhibits a 1300% retention time of its pure-component counterparts for SO2 in a dynamic column breakthrough experiment for deep desulfurization.

Crystal Engineering of a New Hexafluorogermanate Pillared Hybrid Ultramicroporous Material Delivers Enhanced Acetylene Selectivity.

Hybrid ultramicroporous materials (HUMs), metal-organic platforms that incorporate inorganic pillars, are a promising class of porous solids. A key area of interest for such materials is gas separation, where HUMs have already established benchmark performances. Thanks to their ready compositional modularity, we report the design and synthesis of a new HUM, GEFSIX-21-Cu, incorporating the ligand pypz (4-(3,5-dimethyl-1H-pyrazol-4-yl)pyridine, 21) and GeF62- pillaring anions. GEFSIX-21-Cu delivers on two fronts: first, it displays an exceptionally high C2H2 adsorption capacity (≥5 mmol g-1) which is paired with low uptake of CO2 (<2 mmol g-1), and, second, a low enthalpy of adsorption for C2H2 (ca. 32 kJ mol-1). This combination is rarely seen in the C2H2 selective physisorbents reported thus far, and not observed in related isostructural HUMs featuring pypz and other pillaring anions. Dynamic column breakthrough experiments for 1:1 and 2:1 C2H2/CO2 mixtures revealed GEFSIX-21-Cu to selectively separate C2H2 from CO2, yielding ≥99.99% CO2 effluent purities. Temperature-programmed desorption experiments revealed full sorbent regeneration in <35 min at 60 °C, reinforcing HUMs as potentially technologically relevant materials for strategic gas separations.

Efficient purification of CH4 from ternary mixtures by a microporous heterometal-organic framework

Purification of methane (CH4) from multi-component mixtures containing acetylene (C2H2) and carbon dioxide (CO2) is a meaningful but challenging task. We herein reported a heterometal-organic framework, CuIn(ina)4, with microporous channels, which exhibits specific recognition of C2H2 and CO2 through suitable ultramicropores and surface environments. The results of experiments indicate that the title MOF shows high C2H2/CH4 selectivity (20.2) and CO2/CH4 selectivity (5.3). Column breakthrough experiments and theoretical calculations further demonstrate that CuIn(ina)4 can efficiently separate CH4 from ternary mixtures.

Leveraging Surface Chemistry and Pore Shape Engineering in a Metal‐Organic Framework for One‐Step Olefin Purification

AbstractPurifying olefin from ternary paraffin/olefin/alkyne mixtures through a one‐step adsorption process is extremely desirable. Herein, a stable zirconium(IV) metal‐organic framework with a customized pore surface composed of nonpolar phenyl and slightly polar thiophene rings is reported to access the adsorption preference of paraffin and alkyne over olefin. Noteworthily, this material displays a superior ability to discriminate C3 hydrocarbon molecules, which is principally more challenging compared with C2 ones and rarely documented. Computational studies disclose that its featured pore shape fits well with C3 gas molecules, enabling them to get close contact with the immobilized affinity sites. Leveraging surface chemistry and pore shape engineering synergistically gives rise to excellent C3 adsorption capacities (&gt;5 mmol g−1) and concurrently high C3H8/C3H6 (1.4) and C3H4/C3H6 (1.9) selectivities (at 298 K and 1 atm). Dynamic column breakthrough experiments demonstrate that one‐step purification of C2H4 and C3H6 can be simultaneously realized on this material.

Ultramicroporous Lonsdaleite Topology MOF with High Propane Uptake and Propane/Methane Selectivity for Propane Capture from Simulated Natural Gas.

Propane (C3H8) is a widely used fuel gas. Metal-organic framework (MOF) physisorbents that are C3H8 selective offer the potential to significantly reduce the energy footprint for capturing C3H8 from natural gas, where C3H8 is typically present as a minor component. Here we report the C3H8 recovery performance of a previously unreported lonsdaleite, lon, topology MOF, a chiral metal-organic material, [Ni(S-IEDC)(bipy)(SCN)]n, CMOM-7. CMOM-7 was prepared from three low-cost precursors: Ni(SCN)2, S-indoline-2-carboxylic acid (S-IDECH), and 4,4'-bipyridine (bipy), and its structure was determined by single crystal X-ray crystallography. Pure gas adsorption isotherms revealed that CMOM-7 exhibited high C3H8 uptake (2.71 mmol g-1) at 0.05 bar, an indication of a higher affinity for C3H8 than both C2H6 and CH4. Dynamic column breakthrough experiments afforded high purity C3H8 capture from a gas mixture comprising C3H8/C2H6/CH4 (v/v/v = 5/10/85). Despite the dilute C3H8 stream, CMOM-7 registered a high dynamic uptake of C3H8 and a breakthrough time difference between C3H8 and C2H6 of 79.5 min g-1, superior to those of previous MOF physisorbents studied under the same flow rate. Analysis of crystallographic data and Grand Canonical Monte Carlo simulations provides insight into the two C3H8 binding sites in CMOM-7, both of which are driven by C-H···π and hydrogen bonding interactions.

Flexible-robust interlayer space in a 2D metal–organic framework for light hydrocarbons separation

The separation of light hydrocarbons is industrially important and scientifically challenging due to their high similarity in physicochemical properties. Two-dimensional metal–organic frameworks (2D MOFs) assembled by weak supramolecular interactions are more likely to induce structural flexibility and exhibit guest-dependent gate-opening behavior than 3D MOFs, opening new horizons for LHs storage and separation. Here, a 2D MOF (Cu-APC, APC = 2-aminopyrimidine-5-carboxylic acid) with flexible-robust interlayer space was effectively used as an adsorbent to realize C2 and C3 hydrocarbons separation. Evidenced by gas adsorption isotherms and the ideal adsorbed solution theory (IAST) calculations, Cu-APC exhibits moderate C2H2/CO2 selectivity (2.87), high C2H6/C2H4 selectivity (2.27) and unique multistep adsorption behavior toward C3H4/C3H6 at ambient conditions. Moreover, theoretical calculations revealed that C-H···N, C=O···H-C, and C-H···π interactions are formed with C2H2, CO2, C2H4, and C2H6 in the suitable pockets within Cu-APC. The separation performances of Cu-APC for C2H2/CO2, C2H6/C2H4, and C3H4/C3H6 mixtures were also confirmed by column breakthrough experiments.

Spatial Distribution of Nitrogen Binding Sites in Metal‐Organic Frameworks for Selective Ethane Adsorption and One‐Step Ethylene Purification

AbstractThe one‐step purification of ethylene (C2H4) from mixtures containing ethane (C2H6) and acetylene (C2H2) is an industrially important yet challenging process. In this work, we present a site‐engineering strategy aimed at manipulating the spatial distribution of binding sites within a confined pore space. We realized successfully by incorporating nitrogen‐containing heterocycles, such as indole‐5‐carboxylic acid (Ind), benzimidazole‐5‐carboxylic acid (Bzz), and indazole‐5‐carboxylic acid (Izo), into the robust MOF‐808 platform via post‐synthetic modification. The resulting functionalized materials, namely MOF‐808‐Ind, MOF‐808‐Bzz, and MOF‐808‐Izo, demonstrated significantly improved selectivity for C2H2 and C2H6 over C2H4. MOF‐808‐Bzz with two uniformly distributed nitrogen binding sites gave the optimal geometry for selective ethane trapping through multiple strong C−H⋅⋅⋅N hydrogen bonds, leading to the highest C2H2/C2H4 and C2H6/C2H4 combined selectivities among known MOFs. Column breakthrough experiments validated its ability to purify C2H4 from ternary C2H2/C2H4/C2H6 mixtures in a single step.

Spatial Distribution of Nitrogen Binding Sites in Metal-Organic Frameworks for Selective Ethane Adsorption and One-Step Ethylene Purification.

The one-step purification of ethylene (C2 H4 ) from mixtures containing ethane (C2 H6 ) and acetylene (C2 H2 ) is an industrially important yet challenging process. In this work, we present a site-engineering strategy aimed at manipulating the spatial distribution of binding sites within a confined pore space. We realized successfully by incorporating nitrogen-containing heterocycles, such as indole-5-carboxylic acid (Ind), benzimidazole-5-carboxylic acid (Bzz), and indazole-5-carboxylic acid (Izo), into the robust MOF-808 platform via post-synthetic modification. The resulting functionalized materials, namely MOF-808-Ind, MOF-808-Bzz, and MOF-808-Izo, demonstrated significantly improved selectivity for C2 H2 and C2 H6 over C2 H4 . MOF-808-Bzz with two uniformly distributed nitrogen binding sites gave the optimal geometry for selective ethane trapping through multiple strong C-H⋅⋅⋅N hydrogen bonds, leading to the highest C2 H2 /C2 H4 and C2 H6 /C2 H4 combined selectivities among known MOFs. Column breakthrough experiments validated its ability to purify C2 H4 from ternary C2 H2 /C2 H4 /C2 H6 mixtures in a single step.

Ambient temperature NO2 removal by adsorption on robust DMOFs: Regulating water stability, acid stability, and NO2 capacity by methyl functionalization

Nitrogen dioxide (NO2) is a dominant contributor to air pollution and urgently needs to be abated. The catalysis-based deNOx technologies can efficiently remove NO2 at elevated temperatures but fail to effectively deal with ambient NO2 pollution. Selective adsorption by solid porous adsorbents, especially metal-organic frameworks (MOFs), emerges as a promising strategy for ambient NO2 removal. To overcome the biggest challenge in developing low-temperature NO2 adsorbents today – poor stability and thus the inferior cyclable capacity, especially in the presence of water vapor, here we investigated the functionalization of a series of DMOFs with nonpolar methyl (–CH3) groups to regulate their water stability and NO2 adsorption capacity. Among these isoreticular DMOFs, the tetramethyl (TM) functionalized one (Ni-TM DMOF) exhibited a two-fold and 60-times increase in NO2 adsorption capacity under dry (2.2 mmol/g) and wet (1.8 mmol/g) conditions, respectively, over its counterpart without the TM groups (Ni-BDC DMOF). Careful structural characterizations attributed the elevated NO2 adsorption performance of DMOFs to the improved hydrophobicity induced by methyl group decoration under the wet condition. The combination of column breakthrough experiment, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study, and density functional theory (DFT) calculations revealed the NO2 adsorption mechanism under both dry and wet conditions. This work affords not only promising adsorbents for ambient NO2 removal but also new knowledge to guide the design of porous MOFs as robust adsorbents for acid gases capture.

C2H2/CO2 Separation with a Chain‐Type Zn Pyrazolate MOF

AbstractA novel Zn dipyrazolate metal‐organic framework (MOF), Zn(azbpz) (azbpz2−=4,4′‐azobis(3,5‐dimethylpyrazolate), has been synthesized and structurally characterized using micro‐crystal electron diffraction. The framework contains chain‐type secondary building units comprised of tetrahedral Zn2+ ions bridged by pyrazolate groups, resulting in guest‐accessible channels lined with methyl and azo functional groups. CO2, C2H2, C2H4, C2H6, C3H6, and C3H8 gas adsorption isotherms were measured to investigate the potential of Zn(azbpz) as an adsorbent for selective separation of binary gas mixtures. The data reveal selective adsorption of acetylene over CO2, and column breakthrough experiments demonstrate good performance for C2H2/CO2 separation.

Reoxidation of Reduced Peat Organic Matter by Dissolved Oxygen: Combined Laboratory Column‐Breakthrough Experiments and In‐Field Push‐Pull Tests

AbstractElectron transfer to peat particulate organic matter (POM) as terminal electron acceptor (TEA) in anaerobic respiration has been hypothesized to lower methane emissions from peatlands by competitively suppressing methanogenesis and/or allowing for anaerobic oxidation of methane. We herein provide evidence for two critical aspects of this hypothesis: (a) peat POM is present in a reduced state in situ in the anoxic peat subsurface, and (b) reduced POM at the oxic‐anoxic interface in peat soils can be oxidized by dissolved oxygen (DO), restoring its TEA capacity. We reacted reduced POM from three ombrotrophic bogs in Sweden with DO in soil‐packed column‐breakthrough experiments (CBEs), mimicking oxidation reactions at the oxic‐anoxic interface. Breakthrough of DO was substantially retarded relative to the inert tracer bromide, consistent with DO reduction by POM. Control experiments confirmed abiotic DO reduction and excluded DO consumption through aerobic respiration. Modeling DO breakthrough revealed fast and slowly reacting POM moieties with reaction times spanning minutes to days. Complementary push‐pull tests (PPTs) in the anoxic subsurface of one bog confirmed results from laboratory CBEs: lower recoveries of injected DO compared with bromide supported DO reduction by reduced POM. Rates of reduction of injected DO decreased with increasing number of injections, consistent with continuous oxidation of reduced POM. Electron‐donating capacities of POM to DO in CBEs and PPTs were comparable at 40–130 μmol e−/g dry POM. Our results substantiate that POM is a regenerable TEA at oxic‐anoxic interfaces in peat soils and, thereby, may substantially lower CH4 emissions from peatlands.

Three Robust Isoreticular Metal-Organic Frameworks with High-Performance Selective CO2 Capture and Separation.

Based on the hard-soft acid base (HSAB) theory, three robust isoreticular metal-organic frameworks (MOFs) with nia topology were successfully synthesized by solvothermal reaction {[In3O(BHB)(H2O)3]NO3·3DMA (JLU-MOF110(In)), [Fe3O(BHB)(H2O)3]NO3 (JLU-MOF110(Fe)), and [Fe2NiO(BHB)(H2O)3] (JLU-MOF110(FeNi)) (DMA = N,N-dimethylacetamide, H6BHB = 4,4″-benzene-1,3,5-triyl-hexabenzoic acid)}. Both JLU-MOF110(In) and JLU-MOF110(Fe) are cationic frameworks, and their BET surface areas are 301 and 446 m2/g, respectively. By modification of the components of metal clusters, JLU-MOF110(FeNi) features a neutral framework, and the BET surface area is increased up to 808 m2/g. All three MOF materials exhibit high chemical and thermal stability. JLU-MOF110(In) remains stable for 24 h at pH values ranging from 1 to 11, while JLU-MOF110(Fe) and JLU-MOF110(FeNi) persist to be stable for 24 h at pH from 1 to 12. JLU-MOF110(In) exhibits thermal stability up to 350 °C, whereas JLU-MOF110(Fe) and JLU-MOF(FeNi) can be stable up to 300 °C. Thanks to the microporous cage-based structure and abundant open metal sites, JLU-MOF110(In), JLU-MOF110(Fe), and JLU-MOF110(FeNi) have excellent CO2 capture capacity (28.0, 51.5, and 99.6 cm3/g, respectively, under 298 K and 1 bar). Interestingly, the ideal adsorption solution theory results show that all three MOFs exhibit high separation selectivity toward CO2 over N2 (35.2, 43.2, and 43.2 for CO2/N2 = 0.15/0.85) and CO2 over CH4 (14.4, 11.5, and 10.1 for CO2/CH4 = 0.5/0.5) at 298 K and 1 bar. Thus, all three MOFs are potential candidates for CO2 capture and separation. Among them, JLU-MOF110(FeNi) displays the best separation potential, as revealed by dynamic column breakthrough experiments.