Ideal Adsorption Solution Research Articles

Sustainable Metallocavitand for Flue Gas-Selective Sorption: A Multiscale Study

We have used density functional theory, Grand canonical Monte Carlo (GCMC), and ideal adsorption solution theory (IAST) to understand the selective adsorption of flue within the cavity of porous metallocavitand pillarplex (PPX) molecule. Energies associated with the guest@PPX complex formation depict the effectiveness of encapsulation of guest within PPX. PPX is noted to have high selectivity toward the adsorption of Br2, HBr, CS2, H2S, and NO2 over their respective congeners. The strength of bonding and nature of the interaction is deciphered via quantum theory of atoms in molecule, noncovalent interaction, and energy decomposition analysis scheme. The molecules containing acidic hydrogen, viz., H2O, H2S, HF, HCl, and HBr, make hydrogen bonding with the −N atom of the pyrazole ring, and F2 and Cl2 make partially covalent bonding interaction with the −Au atom of PPX. The interaction is mostly of the van der Waals type, except in F2, Cl2, NO, and HF, in which the cumulative contribution of orbital, electro...

A heterometallic metal-organic framework based on multi-nuclear clusters exhibiting high stability and selective gas adsorption.

The design and synthesis of porous heterometallic metal-organic frameworks (MOFs) with high thermal and chemical stability is a challenging task at present. In this work, by the heterometallic cooperative crystallization (HCC) approach, an original heterometallic MOF based on a tetra-carboxylic ligand has been solvothermally synthesized [In6O3Tb3O(CBDA)3]·18DMF·3H2O (In/Tb-CBDA) [CBDA = 5,5'-(carbonylbis(azanediyl))-diisophthalic acid, DMF = N,N-dimethylformamide]. The framework of In/Tb-CBDA is cooperatively assembled from the rarely reported tetra-nuclear In4O2(COO)4 and tri-nuclear Tb3O(COO)6 clusters, and an organic ligand. Topological analysis indicates that In/Tb-CBDA exhibits a new (4,4,6)-connected topology with the Schläfli symbol (4·63·82)6(43·69·83)2(62·84)3. Noteworthy, forming multi-nuclear metal clusters prompts the framework to maintain high stability under the conditions of heating to 150 °C, exposure to air, and soaking in acidic and basic aqueous solutions for 12 h. After desolvation, In/Tb-CBDA shows permanent porosity proved by N2 adsorption isotherms. In addition, theoretical ideal adsorption solution theory (IAST) calculation indicates that In/Tb-CBDA displayed high selective adsorption of CO2/CH4, C2H6/CH4 and C3H8/CH4 at room temperature. This work shows a striking example of a porous heterometallic MOF material with high thermal and chemical stability, which exhibits high-efficiency selective gas adsorption behaviour.

Removal of Microcystin-LR from spiked natural and synthetic waters by anion exchange

Cyanobacterial blooms are becoming a serious challenge across the globe due to changing climate and rainfall patterns as a consequence of human activities. In the present study, the fundamental interactions involved during the removal of Microcystin-LR (MCLR), one of the most commonly occurring cyanobacterial toxins, were investigated by employing strongly basic anion exchange (IX) resins. Several factors including the stoichiometric coefficients, competitive fractions and solute affinities were determined under various concentrations of inorganic ions and natural organic matter. The results indicated that suphates were the most competitive fractions with high affinity (α (affinity coefficient) values ~ 9) followed by nitrates (α ~ 4.7) and NOM fractions (α ~ 4.5, p < 0.05). The Equivalent Background Concentration Mode (EBC), that arises from the Ideal Adsorption Solution Theory (IAST), indicated a competitive fraction of ~2 μeq/L NOM, which approximates to <10% of the initial NOM concentrations, indicating a small fraction of the NOM resulting in the competitive effect. Further, studies with natural surface waters indicated that the MCLR uptake could be modeled using the IAST-EBC model and the IX resin could simultaneously removal of >90% of NOM, inorganic ions and MCLR at resin dosages of 3.6 meq/L or higher.

Single and Binary Mixture Adsorption Behaviors of C6–C8 Hydrocarbons on Silica–Alumina Gel

To ensure the technical use of natural gas, heavy hydrocarbons and other components must be separated. Therefore, in this work the adsorption of C6–C8 hydrocarbons n-hexane, n-heptane, n-octane, benzene, toluene, and cyclohexane on a commercial silica–alumina gel (Sorbead H) was investigated in experiments and dynamic simulations. Single and binary mixture equilibrium isotherms were determined from cumulative breakthrough curve experiments on a fixed bed adsorber at 25–75 °C and 1.3 bar (abs) in the trace range up to approximately 5000 ppmmol. The adsorption behavior is interpreted on the basis of the molecular structure of the adsorptive, the surface chemistry, and the pore structure of the adsorbents. Binary mixture isotherms were calculated using the theory of the ideal adsorbed solution (IAST). The results were in good agreement with experimental data. The adsorption dynamics was investigated by breakthrough curve experiments and simulated dynamically using an isothermal model based on mass balances a...

Controlled Construction of Cu(I) Sites within Confined Spaces via Host-Guest Redox: Highly Efficient Adsorbents for Selective CO Adsorption.

Here, we designed a double-solvent/host-guest redox combined strategy to construct Cu+ sites in metal-organic frameworks (MOFs) for the first time. As a proof of concept, a representative MOF MIL-100(Fe) with tunable valence states of cations was employed as the host. The combined strategy realizes selective introduction of Cu2+ precursors to the interior pores of MIL-100(Fe), remarkably minimizing the aggregation of Cu2+ and subsequently formed Cu+ species. Owing to the proper reducibility of in situ formed Fe2+ in the frameworks, controlled conversation of Cu2+ to Cu+ with ∼100% yield is achieved in the absence of any additional reducing agents. These characteristics make the obtained materials Cu+-modified MIL-100(Fe) highly active in selective CO adsorption. The CO adsorption capacity is up to 3.75 mmol·g-1 at 298 K and 1 bar, which is superior to all other Cu+-containing adsorbents reported so far such as CuCl/activated carbon (2.5 mmol·g-1), CuCl/γ-Al2O3 (1.0 mmol·g-1), and CuCl/SBA-15 (0.50 mmol·g-1). The same adsorbent also exhibits quite high selectivity of CO over N2, and the ideal adsorption solution theory selectivity reaches 424. The outstanding CO adsorption performance make the present adsorbents great potential in separation of CO from various mixtures.

CO2 Capture &amp;amp; Separation in Microporous Materials: A Comparison Between Porous Carbon and Flexible MOFs

The stereotype of flexible MOFs(Amino-MIL-53) and carbonized porous carbon prepared from renewable resources is successfully synthesized for CO2 reduction application. The textural properties of these microporous materials are investigated, and their CO2 storage capacity and separation performance are evaluated. Owing to the combined effects of CO2-Amino interaction and its flexibility, a CO2 uptake of 2.5 mmol g−1 is observed in Amino-MIL-53 at 20 bar 298 K. In contrast, CH4 uptake in Amino-MIL-53 is very low up to 20 bar, implying potential sorbent for CO2/CH4 separation. Carbonized samples contain a small quantity of metal residues(K, Ca, Mg, S), resulting in naturally doped porous carbon. Due to the trace metal, even higher CO2 uptake of 4.7 mmol g−1 is also observed at 20 bar 298 K. Furthermore, the CH4 storage capacity is 2.9 mmol g−1 at 298 K and 20 bar. To evaluate the CO2 separation performance, the selectivity based on ideal adsorption solution theory for CO2/CH4 binary mixtures on the presented porous materials is investigated.

Strategic Design and Functionalization of an Amine-Decorated Luminescent Metal Organic Framework for Selective Gas/Vapor Sorption and Nanomolar Sensing of 2,4,6-Trinitrophenol in Water.

On the basis of the strategic design of a triazine-based dicarboxylate ligand with two primary amino groups and one secondary amino group, an amine-functionalized autofluorescent and polar three-dimensional metal organic framework (MOF) {[Cd(ATAIA)]·4H2O} n (1), where H2ATAIA = 5-((4,6-diamino-1,3,5-triazin-2-yl)amino)isophthalic acid, has been synthesized under two different solvothermal conditions and structurally characterized. Single-crystal X-ray analysis reveals that 1 crystallizes in the orthorhombic polar space group Fdd2, where each ATAIA ligand acts as a linear linker to connect four Cd(II) centers, resulting in the formation of a three-dimensional framework with a repeat of a double helical metal chain. It has been further characterized by elemental analysis, UV-vis and Fourier transform infrared spectroscopy, and thermogravimetric analysis. Its bulk phase purity and stability in aqueous acid and base solutions are confirmed by powder X-ray diffraction. Both field emission scanning electron microscopy and high resolution transmission electron microscopy images of 1 reflect the formation of microflowers by self-assembly of nanopetals. With the dehydrated framework of 1, sorption studies of different gases (N2, H2, and CO2) as well as polar and nonpolar solvents, such as water, benzene (Bz), and cyclohexane (Cy), have been performed. The CO2 sorption isotherm depicts type I isotherm at 298 and 273 K and type IV isotherm at 195 K. Furthermore, with an uptake of 129.2 cm3 g-1 (25.62 wt %) at 195 K, sorption of CO2 is selective over N2 (77 K) and H2 (77 K) because of the strong adsorbate-adsorbent interaction as clearly evident from an isosteric heat of adsorption ( Qst) at zero coverage of 37.5 kJ mol-1, which is exceptionally higher than that of other functionalized MOFs. Using the ideal adsorption solution theory calculation for a CO2/N2 (15:85) mixture, selectivity values are found to be 54.08 (298 K) and 46.96 (273 K) at 100 kPa. For a major application, activated 1 has been utilized for selective and ultrafast detection of 2,4,6-trinitrophenol (TNP) in water with a limit of 0.94 nM (0.2 ppb), which supersedes any previous reported value. Excellent recyclability and stability of 1 for sensing experiments have been established. Time-resolved fluorescence studies and density functional theory calculations have been used to establish its mechanism of action. Furthermore, a prototype experiment for the real-time sensing of TNP in the vapor phase by fluorescence microscopy provides an easy colorimetric monitoring.

Hydrogen separation by adsorption: Experiments and modelling of H2-N2-CO2 and H2-CH4-CO2 mixtures adsorption on CuBTC and MOF-5

In this paper, we present the adsorption data of two ternary mixtures (H2-N2-CO2 and H2-CH4-CO2) on MOF-5 and CuBTC, obtained via a recirculating volumetric method. The measurements were performed along constant composition and constant pressure domains. The constant pressure data outlines the existence of one-component azeotrope-like crossovers in the adsorbed phase diagrams. Such azeotropic behaviours are related to the deviation between selectivities in the ternary and the equivalent binary mixtures. Furthermore, the capabilities of three models, Extended Langmuir, Extended Toth and Ideal Adsorption Solution Theory (IAST), to predict the ternary mixture adsorption from pure-component data are discussed.

Zeolites for CO2-CO-O2 Separation to Obtain CO2-Neutral Fuels.

Carbon dioxide release has become an important global issue due to the significant and continuous rise in atmospheric CO2 concentrations and the depletion of carbon-based energy resources. Plasmolysis is a very energy-efficient process for reintroducing CO2 into energy and chemical cycles by converting CO2 into CO and O2 utilizing renewable electricity. The bottleneck of the process is that CO remains mixed with O2 and residual CO2. Therefore, efficient gas separation and recuperation are essential for obtaining pure CO, which, via water gas shift and Fischer-Tropsch reactions, can lead to the production of CO2-neutral fuels. The idea behind this work is to provide a separation mechanism based on zeolites to optimize the separation of carbon dioxide, carbon monoxide, and oxygen under mild operational conditions. To achieve this goal, we performed a thorough screening of available zeolites based on topology and adsorptive properties using molecular simulation and ideal adsorption solution theory. FAU, BRE, and MTW are identified as suitable topologies for these separation processes. FAU can be used for the separation of carbon dioxide from carbon monoxide and oxygen and BRE or MTW for the separation of carbon monoxide from oxygen. These results are reinforced by pressure swing adsorption simulations at room temperature combining adsorption columns with pure silica FAU zeolite and zeolite BRE at a Si/Al ratio of 3. These zeolites have the added advantage of being commercially available.

Pyrrolic N-enriched carbon fabricated from dopamine-melamine via fast mechanochemical copolymerization for highly selective separation of CO2 from CO2/N2

A pyrrolic N-enriched microporous carbon composite was synthesized using mechanochemical strategy via copolymerized melamine/dopamine (PDA/MA) within ultra-short reaction time (30 min) for CO2 capture from gaseous mixture of CO2/N2. Dopamine doping efficiently restrained the sublimation of melamine during calcination, which leaded to higher yield (>70 wt%) in comparison with pure C3N4. The synthesized carbon composite possessed ultra-microporous structure (5.3–5.6 Å) and abundant (pyrrolic N of 13.1 wt%) CO2-philic sites. Results showed that PDA0.3/MA0.7-2 exhibited high CO2 capacity of 16.0 wt% (3.64 mmol/g) at 298 K and 20.3 wt% (4.6 mmol/g) at 273 K and 1.0 bar pressure. The isosteric heat of adsorption (Qst) was 37.4 kJ/mol, indicating a strong interaction of the composite with CO2 molecules. Ideal adsorption solution theory demonstrated that PDA0.3/MA0.7-2 possessed a super high CO2 selectivity (108) in CO2/N2 (10:90) mixture at 273 K. High CO2 capacity and selectivity, green and fast fabrication strategy and cost effective raw materials make the proposed novel PDA/MA carbons as promising candidates for CO2 capture from post-combustion flue gases.

Controllable synthesis of bifunctional porous carbon for efficient gas-mixture separation and high-performance supercapacitor

It is notably challenging to fabricate controllable heteroatom-doped porous carbons for both highly effective mixed-gas separation and supercapacitor electrodes. In this work, novel algae-derived nitrogen-containing porous carbons were prepared as bifunctional materials. The pore structure of obtained carbons could be easily tailored by altering activation temperature or porogen/biomass ratio. The as-prepared porous carbon has a very high specific surface area of 1538.7 m2 g−1 and a large pore volume of 0.99 cm3 g−1 with a high N content of 2.77 wt%. As a solid-state adsorbent, the algae-derived carbon has an excellent CO2 adsorption capacity of 5.7 and 3.9 mmol g−1 at 273 and 298 K, respectively. The extraordinarily high CO2/N2, CO2/CH4, and CH4/N2 selectivity are demonstrated by the ideal adsorption solution theory (IAST) calculation and dynamic adsorption breakthrough experiments. As an electroactive material, the porous carbon exhibits outstanding capacitive performance in 6 M KOH aqueous electrolyte, with the specific capacitance of 287.7 and 190.0 F g−1 at 0.2 A g−1 in a three- and two-electrode system, respectively. Furthermore, the obtained carbon shows outstanding rate capability of 79.3% at 10 A g−1 and unprecedented cycling stability with 98% capacitance retention at 10 A g−1 after 8000 cycles as coin cell. This report introduces a biomass-derived and low-cost pathway to design porous carbon materials for efficient solid adsorbents and supercapacitive electrode materials.

Electrochemical synthesis, characterization and application of a microstructure Cu3(BTC)2 metal organic framework for CO2 and CH4 separation

The electrochemical route is a promising and environmentally friendly technique for fabrication of metal organic frameworks (MOFs) due to mild synthesis condition, short time for crystal growth and ease of scale up. A microstructure Cu3(BTC)2 MOF was synthesized through electrochemical path and successfully employed for CO2 and CH4 adsorption. Characterization and structural investigation of the MOF was carried out by XRD, FE-SEM, TGA, FTIR and BET analyses. The highest amount of carbon dioxide and methane sorption was 26.89 and 6.63 wt%, respectively, at 298 K. The heat of adsorption for CO2 decreased monotonically, while an opposite trend was observed for CH4. The results also revealed that the selectivity of the developed MOF towards CO2 over CH4 enhanced with increase of pressure and composition of carbon dioxide component as predicted by the ideal adsorption solution theory (IAST). The regeneration of as-synthesized MOF was also studied in six consecutive cycles and no considerable reduction in CO2 adsorption capacity was observed.

Modelling equilibrium adsorption of single, binary, and ternary combinations of Cu, Pb, and Zn onto granular activated carbon.

Elevated concentrations of heavy metals in water can be toxic to humans, animals, and aquatic organisms. A study was conducted on the removal of Cu, Pb, and Zn by a commonly used water treatment adsorbent, granular activated carbon (GAC), from three single, three binary (Cu-Pb, Cu-Zn, Pb-Zn), and one ternary (Cu-Pb-Zn) combination of metals. It also investigated seven mathematical models on their suitability to predict the metals adsorption capacities. Adsorption of Cu, Pb, and Zn increased with pH with an abrupt increase in adsorption at around pH 5.5, 4.5, and 6.0, respectively. At all pHs tested (2.5-7.0), the adsorption capacity followed the order Pb > Cu > Zn. The Langmuir and Sips models fitted better than the Freundlich model to the data in the single-metal system at pH 5. The Langmuir maximum adsorption capacities of Pb, Cu, and Zn (mmol/g) obtained from the model's fits were 0.142, 0.094, and 0.058, respectively. The adsorption capacities (mmol/g) for these metals at 0.01mmol/L equilibrium liquid concentration were 0.130, 0.085, and 0.040, respectively. Ideal Adsorbed Solution (IAS)-Langmuir and IAS-Sips models fitted well to the binary and ternary metals adsorption data, whereas the Extended Langmuir and Extended Sips models' fits to the data were poor. The selectivity of adsorption followed the same order as the metals' capacities and affinities of adsorption in the single-metal systems.

Hybrid Postsynthetic Functionalization of Tetraethylenepentamine onto MIL-101(Cr) for Separation of CO2from CH4

To remove CO2 from CH4, tetraethylenepentamine was grafted onto coordinatively unsaturated centers of MIL-101(Cr) by postsynthetic functionalization: wet impregnation at 298 K, followed by grafting, drying, and washing. Compared to MIL-101(Cr), TEPA–MIL-101(Cr) showed 54% higher CO2 adsorption at 1 bar and 98% reduction of CH4 adsorption at 60 bar. The ideal adsorption solution theory (IAST) selectivity of CO2/CH4 for a binary gas mixture of 2% CO2 + 98% CH4 at 298 K and 60 bar predicted by the Toth equation was found to be 11 and 598 for ungrafted and grafted MIL-101(Cr), respectively. Single column breakthrough tests were performed for upgrading the 2% CO2 + 98% CH4 mixture to liquefied quality of natural gas (CO2 < 50 ppm) under various operating conditions including different temperatures and total amount of purge gas at the fixed pressure of 60 bar and temperature of 298 K. At the feed flow rate of 1000 sccm, the TEPA–MIL-101(Cr) extrudates obtained 0.89 mmol/g CO2 adsorption capacity and nearly 83% ...

Experimental benchmark data of CH4, CO2 and N2 binary and ternary mixtures adsorption on MOF-5

Abstract We present benchmark adsorption data of CH4, CO2 and N2 binary and ternary mixtures on MOF-5 at 297 K and pressures up to 1500 kPa obtained via the isotope exchange technique (IET) and a predictive volumetric method. The ternary mixtures data are organized in two different domains: constant composition and constant pressure planes. The constant composition data show quasi-constant selectivity in the entire pressure range. The constant pressure data showed the existence of azeotrope-like crossover for CH4 along the N2 and CO2 paths. However, these crossovers do not correspond to a reversal in the adsorbent’s affinity for CH4. The obtained experimental data is in accord with ideal adsorption solution theory (IAST).

Pyridine-Functionalized and Metallized Meso-Macroporous Polymers for Highly Selective Capture and Catalytic Conversion of CO2 into Cyclic Carbonates

Pyridinic nitrogen functionalized porous organic polymers (PDVB-VP-x, where x represents the volume ratio of VP/DVB) with hierarchical meso-macroporosity were template-free synthesized from solvothermal cross-linking of 4-vinylpyridine with divinylbenzene. PDVB-VP-x can be used as effective supports for metalation with Co2+ and Zn2+, giving metal@PDVB-VP-x composites. CO2 and N2 adsorption tests demonstrate that metal@PDVB-VP-x have competitive capacities for CO2 at low relative pressure of 0.15 bar (0.58–0.89 and 0.51–0.76 mmol g–1 at 0 and 25 °C) and extraordinary Ideal Adsorption Solution Theory (IAST) selectivities for CO2/N2 (84.5–96.7 at 0 °C and 130.5–163.5 at 25 °C). The metal@PDVB-VP-x composites also exhibit impressive activities in catalyzing conversion of CO2 from dilute sources (15% balanced in N2) into cyclic carbonates under ambient condition. Interestingly, the metal@PDVB-VP-x composites have excellent water-tolerant property, endowing them with potentially important applications in select...

Thermodynamics and kinetics of CH4/CO2 binary mixture separation by metal-organic frameworks from isotope exchange and adsorption break-through

We combine the isotope exchange technique (IET) with the conventional Sieverts method, microcalorimetry, breakthrough experiments and multi-scale modelling to comprehensively and quantitatively investigate the thermodynamics and kinetics of equimolar CH4/CO2 mixture separation in metal organic frameworks. The prototypical MOF-5 is selected for this work as it allows benchmarking our binary mixture results with the pure gas data widely reported in the literature. For the first time, an experimental binary gas adsorption isotherm of CH4/CO2 on MOF-5 is reported and compared with the respective pure gas isotherms. The equilibrium thermodynamic selectivity from the IET experiments for the equimolar CH4/CO2 separation is found to be 8.3 while a much lower value of 2.83 is obtained from the ideal adsorption solution theory (IAST). The large standard deviation of the model selectivities and the significant deviation of averaged model selectivity from the experimental one clearly reinforces the necessity to determine the selectivity reliably using experiments. The kinetic selectivity for the binary mixture separation determined by combining the results of IET with the linear driving force (LDF) model is 0.73. The co-adsorption heats and excess uptake of both gases in mixtures are lower than those of pure gases; we observe that the intrinsically weaker sorption of CH4 on MOF-5 is further weakened by the presence of strongly interacting CO2. Thermodynamic and kinetic selectivities and the co-adsorption heats quantitatively suggests that CH4/CO2 separation is driven by the equilibrium thermodynamic factors with no significant contribution from kinetic factors.

Adsorption and desorption dynamics of CF4 on activated carbon beds: Validity of the linear driving force approximation for pressure-changing steps

Adsorption and desorption dynamics of CF4 on an activated carbon bed were studied experimentally and theoretically, focusing on pressure-changing steps. The theoretical model used the ideal adsorbed solution (IAS) theory and the linear driving force (LDF) approximation as equilibrium and mass transfer models, respectively. Adsorption breakthrough curves of raw CF4 gas (500, 1,000, and 1,500 ppm) were well predicted by the theoretical model and the diffusion time constant for CF4 was found to be 3.3×10−3 s−1 from breakthrough curve fitting. Changes in the CF4 concentration during depressurization could be easily predicted using the above mathematical model when the half-cycle time (θ c ) was above 0.1. However, significant discrepancies were observed between the predicted CF4 concentrations and the experimental data when θ c was 0.1. Nakao and Suzuki also reported that proportional constant of LDF approximation (=KD e /R p 2) needs to be modified when θ c is less than 0.1.

Pillar-Layered Metal-Organic Framework with Sieving Effect and Pore Space Partition for Effective Separation of Mixed Gas C2H2/C2H4.

The removal of acetylene from the industrial feed gas to purify the ethylene is an important and challenging issue. The adsorption-based separation is a more environmentally friendly and cost-effective method compared to the current removal approaches such as partial hydrogenation and solvent extraction, while facing the challenge of developing materials with high C2H2/C2H4 selectivity and C2H2 capacity. Herein, by expanding mixed-metal organic frameworks (M'MOFs) structure with high C2H2/C2H4 selectivity, we report a pillar-layered MOF, {[Cd5(MPCZ)2(BDC)3(NO3)2(H2O)4]·G}n (MECS-5), which not only inherits the sieving effects of M'MOF series but also develops its own characteristic-the 2D layer with expanding space and the plane pore-partition group to "cover" it. MECS-5 shows higher ideal adsorption solution theory C2H2/C2H4 selectivity than the most reported MOFs, especially more than 5 times higher than MOF-74 series while displaying great enhancement in the C2H2 capacity, more than 2 times higher compared to the M'MOF. The column breakthrough experiment further proves the possibility of MECS-5a for real industrial ethylene purification.

Recovery of Multicomponent Shale Gas from Single Nanopores

The adsorption of multicomponent gas mixtures in shale formations and their recovery are of great interest to the shale gas industry. Here we report molecular dynamics simulations of the adsorption of methane/ethane mixtures in 2 and 4 nm-wide nanopores and their recovery from these nanopores. Surface adsorption contributes significantly to the storage of methane and ethane inside the pores, and ethane is enriched inside the nanopores in equilibrium with bulk methane–ethane mixtures. The enrichment of ethane is enhanced as the pore is narrowed but is weakened as the pressure increases due to entropic effects. These effects are captured by the ideal adsorbed solution (IAS) theory, but the theory overestimates the adsorption of both gases. Upon opening the mouth of the nanopores to gas baths with lower pressure, both gases enter the bath. The production rates of both gases show only weak deviation from the square root scaling law before the gas diffusion front reaches the dead end of the pores. The ratio of...