Ideal Adsorption Solution Research Articles

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.

Hydrocarbons (C8–C12) separation in porous metallocavitand M-PPX (M = Cu, Ag, Au): From computational insight

High throughput computational approach has been employed to investigate the adsorption and separation of C8–C12 hydrocarbons (HCs) on a tube-shaped metallocavitand, pillarplex (PPX). The Cu (I), Ag (I), and Au (I) seamed PPX and their HC complexes has been examined using density functional theory (DFT), proclaiming Cu-PPX has a higher binding affinity with the HCs whereas Ag-PPX is lower. The thermodynamic properties reveal the host–guest complex is stable at ambient condition. Noncovalent interaction (NCI) analysis shows the interaction of guests within the cavity of PPX is mainly attributed by Van der Waals type. The energy decomposition analysis (EDA) enunciates the percentage contribution of dispersion interaction (ΔEdisp) is 59–62%, the electrostatic (ΔEelct) and orbital (ΔEorb) terms have a moderate contribution towards the total binding energy. The Grand canonical Monte Carlo (GCMC) simulation manifests the Cu-PPX and Au-PPX are the ideal hosts with the optimum capacity to store HCs at ambient conditions. The octane uptake is 18.01, 17.50, and 25.31 cm3STP/g in Cu, Ag and Au-PPX and the uptake reduces upon increasing the HC chain length. The isosteric heat of adsorption (Qst) is corroborated with the computed DFT data at ambient setup. The ideal adsorption solution theory (IAST) claims the C8 selectivity in Cu, Ag and Au-PPX is optimum at 298 K and the increasing temperature from 298 K to 323 K, the selectivity of the C9 and C12 in Cu-PPX and Au-PPX, respectively is remarkable after the complete separation of C8. Hence Cu-PPX and Au-PPX is the potential candidate for industrial use to separate the heavy HCs.

Two metal-organic frameworks based on tetracarboxylic ligand exhibiting high performance for gas adsorption and separation

Developing porous materials for purification of acetylene is of great significance, but remains challenging. Currently, the use of metal-organic frameworks (MOFs) for gas adsorption separation has received substantial research interest. Herein, based on the tetracarboxylic acid ligand H4TPTA ([1,1':3′,1″-terphenyl]-4,4′,4″,6′-tetracarboxylic acid), two MOFs (ErTPTA and CdTPTA) constructed by trinuclear cluster secondly building units (SBUs) have been successfully synthesized. They are three dimensional (3D) framework with 1D rhomboid channels, demonstrating a (4,8)-connected scu network. A series of gas adsorption tests were performed and the both compounds exhibited outstanding gas selective adsorption performance. Accordingly, the ideal adsorption solution theory (IAST) is used to simulate the adsorption selectivity, the selectivity of CdTPTA for CO2/CH4 is 11.85 (0.5:0.5) and 17.02 (0.05:0.95), and for C2H2/CH4 is 11.81 (0.5:0.5); the selectivity of ErTPTA for C2H2/CO2 is 4.45 (0.5:0.5).

RUPTURA: simulation code for breakthrough, ideal adsorption solution theory computations, and fitting of isotherm models

ABSTRACT We present the RUPTURA code (https://github.com/iraspa/ruptura) as a free and open-source software package (MIT license) for (1) the simulation of gas adsorption breakthrough curves, (2) mixture prediction using methods like the Ideal Adsorption Solution Theory (IAST), segregated-IAST and explicit isotherm models, and (3) fitting of isotherm models on computed or measured adsorption isotherm data. The combination with the RASPA software enables computation of breakthrough curves directly from adsorption simulations in the grand-canonical ensemble. RUPTURA and RASPA have similar input styles. IAST is implemented near machine precision but we also provide several explicit mixture prediction methods that are non-iterative and potentially faster than IAST. The code supports a wide variety of isotherm models like Langmuir, Anti-Langmuir, BET, Henry, Freundlich, Sips, Langmuir-Freundlich, Redlich-Peterson, Toth, Unilan, O'Brian & Myers, Asymptotic Temkin, and Bingel & Walton. The isotherm model parameters can easily be obtained by the fitting module. Breakthrough plots and animations of the column properties are automatically generated. In addition to highlighting the code, we also review all the developed techniques from literature for mixture prediction, breakthrough simulations, and isotherm model fitting, and provide a tutorial discussing the workflows.

Mechanochemical synthesized amino-functionalized ultramicroporous ZIF based mixed-matrix membranes for CO2 separation

Mixed-matrix membranes (MMMs) have arisen as an energy-saving and efficient candidate for CO2 separation that can mitigate the greenhouse effect. However, challenges still remain in achieving good filler-polymer compatibility and high separation performance. Herein, a mechanochemistry method is proposed to synthesize an amine-functionalized ultramicroporous ZIF-62 (ZIF-UC-6) with good CO2 affinity. Amino functional groups and open metal sites are introduced into ZIF-UC-6, which significantly improve its CO2 adsorption capacity of ZIF-62. According to the ideal adsorption solution theory (IAST) calculation, the CO2/CH4 and CO2/N2 selectivity of ZIF-UC-6 is ∼80 and ∼140, respectively. Besides, when ZIF-UC-6 is incorporated into Pebax, hydrogen bonds can form between filler and polymer, which can increase the interfacial compatibility in the MMMs. The optimized membrane possesses a CO2 permeability of ∼560 barrer, together with high CO2/CH4 and CO2/N2 selectivity of 41.8 and 86.2, surpassing the corresponding upper bounds. Moreover, the prepared MMMs have good pressure resistance and long-term stability. This work demonstrates an effective route for developing MMMs with good interfacial compatibility and high CO2 separation performance for potential industrial applications.

Ultra‐microporous MAF stu‐1 modified by ammonia for efficient CO2 capture

AbstractA series of ultra‐microporous rod‐shaped three‐dimensional metal organic frameworks MAF stu‐1 modified with different amounts of ammonia water were synthesized by solvothermal method using chelated nitrogen‐containing ligands, which was applied to CO2 capture and exhibited excellent adsorption performance and CO2/N2 (15:85, v/v) separation efficiency. MAF stu‐1‐C regulated by .13 mol NH3 had small pore size of 4.9 Å and uncoordinated imidazole nitrogen sites in the channel, which were beneficial to improving CO2 adsorption capacity and selectivity. The maximal CO2 adsorption capacity of MAF stu‐1‐C was 110 cm3/g, exhibiting excellent CO2 capture ability and cycle stability. The ideal adsorption solution theory (IAST) model was used to calculate the adsorption and separation ratio of CO2 to N2. The CO2 to N2 selectivity of the modified adsorbent was more than 100. Furthermore, the adsorption heat of MAF stu‐1‐C for CO2 was calculated to be about 35 kJ/mol by virial equation fitting method, indicating that the modified adsorbent also had remarkable regeneration performance.

Microporous carbon coated zeolite particles for efficient carbon capture from wet flue gas

Carbon capture plays an important role in reducing CO2 emissions, and selective adsorption of CO2 is attracting more and more attention. Consider the fact that the actual flue gas always contains the water molecule which is preferentially adsorbed onto the pore surface of adsorbent, resulting in a significant reduction of CO2 capacity and selectivity. In this contribution, we design and prepare a series of microporous carbon coated commercial zeolite 13X particles (13X@MPC) by pyrolysis of polyvinylidene fluoride (PVDF) where the uniform microporous layer is coated on the surface of zeolite 13X beads. After coated with microporous carbon layer, zeolite 13X turns into hydrophobic from hydrophillic. An optimized sample (13X@MPC(25,550)) displays a high CO2 uptake (76.2 cm3 g−1) similar to 13X (80.5 cm3 g−1) and a low H2O uptake (157.1 cm3 g−1) half to 13X (315.2 cm3 g−1). The ideal CO2/N2 selectivity is predicted as 215 by using the ideal adsorption solution theory. The breakthrough separation experiment further verifies the excellent carbon capture ability of 13X@MPC(25,550) from wet flue gas, where the CO2 capacity (26.5 cm3 g−1) and CO2/N2 selectivity (56.2) are greatly improved to zeolite 13X (6.8 cm3 g−1 and 12.5) under the same condition. The results of this paper can be extended to other water-containing gas separation, such as air separation, natural gas purification, etc.

One-pot synthesis of self S-doped porous carbon for efficient CO2 adsorption

Considering the rising environmental and efficiency concerns, the development of porous carbon via a surface decoration approach has received great attention for selectively adsorb CO2 from the flue gas. Herein, self-S-doped porous carbon was prepared from petroleum coke with high sulfur content (PHS) utilizing KOH as an activating agent. The effect of the activating temperatures and the KOH/PHS mass ratio on the physical feature and CO2 uptake performance of the as-synthesis porous carbons was fully examined. The optimal sample (PHS-650-3) presents the specific BET surface area and total pore volume of 1278 m2/g and 0.56 cm3/g, respectively. The PHS-650-3 sample displayed the maximum CO2 adsorption capacity of 4.18 and 5.57 mmol g−1 at 25 and 0 °C and 1 bar thanks to its enhanced textural characteristics and high amount of sulfur functionality on the surface. Last but not least, the as-synthesized S-doped porous carbon shows ideal adsorption solution theory (IAST) CO2/N2 selectivity of 21, fast adsorption kinetics, suitable heat of adsorption value and stable uptake capacity upon consecutive adsorption cycles, claiming its readily potential CO2 adsorption applications.

Al‐based Isoreticular Metal‐Organic Frameworks with MIL‐53 Topology as Effective Adsorbents in Methane Purification

AbstractIn the present investigation, an isoreticular series of Al‐based metal‐organic frameworks (MOFs) with MIL‐53 topology namely, MIL‐53(Al)‐FA, MIL‐53(Al)‐BDC, MIL‐53(Al)‐NDC and MIL‐53(Al)‐BPDC formed by organic linkers with different molecular size and correlated porosity were examined for their adsorption capacity for C3H8, C3H6, C2H4, and CH4, and C3H8/CH4, C3H6/CH4, C2H4/CH4 separation selectivity. C3H8 and C3H6 adsorption is found to be sensitive to van der Waals forces and increases with increasing micropore volume of the MOFs. Ideal Adsorption Solution Theory (IAST) has been applied to estimate binary C3H8/CH4, C3H6/CH4 (C3/C1), and C2H4/CH4 (C2/C1) selectivity. The MOFs investigated have shown high C3/C1 selectivity with MIL‐53(Al)‐FA exhibiting exceptional C3H8/CH4 and C3H6/CH4 selectivity of 330 and 246, respectively, for the 5 : 95 (v/v) mixtures. MIL‐53(Al)‐FA also exhibited the highest C2/C1 selectivity among them. The high affinity of MIL‐53 Al‐based MOFs for C3 and C2 hydrocarbons over C1 make them suitable as adsorbents for methane purification.

Design and Screening of Metal-Organic Frameworks for Ethane/Ethylene Separation.

Separation of ethane and ethylene is considered to be industrially important for various chemical processes, but their similarities make the process expensive. In this study, we integrated computational screening with machine learning to find optimal metal-organic frameworks (MOFs) with high ethane/ethylene selectivity. Using our algorithm, a hypothetical MOF structure with an ideal adsorption solution theory selectivity of 3.6 at 298 K and 1 bar was discovered. Furthermore, structural analysis was implemented, and the full adsorption isotherm of some of the top structures was obtained.

Sulfonated Phenol–Formaldehyde Resins for Highly Efficient, Selective, and Reversible Adsorption of NH3

Currently available liquid absorbents and porous adsorbents for capturing NH3 are often unfavorable in terms of possessing high stability and reusability. Herein, three novel sulfonated phenol–formaldehyde (SPF) resins with almost non-porosity were prepared through a facile polymerization of various phenol sulfonates with formaldehyde and applied to the adsorption of NH3. It is demonstrated that the SPF–Na resin displayed excellent reversibility and good stability for efficient NH3 adsorption (12.87 mmol·g–1) and superior ideal adsorption solution theory selectivities for 3% NH3/97% N2 (5076) and 3% NH3/97% H2 (2619) at 298.2 K and 1.0 bar even in 20 adsorption–desorption cycles, whereas common PF resin only achieved a very low capacity of 1.9 mmol·g–1. Column breakthrough results further confirmed that the SPF–Na resin showed good performance in selective adsorption of 3% NH3 in the mixture of NH3/N2/H2. Nonporous SPF resins with high stability, desired capacity, and outstanding reversibility are perceived as promising solid adsorbents for effectively capturing NH3 in the ammonia industry.

Adsorption separation of O2/N2 by Li-RHO zeolite with high oxygen selectivity

Zeolites traditionally used for air separation are generally N2 selective adsorbents. However, separation of air by adsorption of lesser amounts of O2 is more desirable. In this study, RHO zeolite was successfully synthesized by the hydrothermal method, and a high oxygen selective adsorbent was developed by introducing Li+ with different exchange degrees into the RHO zeolite framework by ion exchange. The equilibrium isotherms for the adsorption of Li-RHO zeolites with different ion exchange degrees on the pure components O2 and N2 were measured and fitted with the Langmuir model equation. The adsorption results showed that the cation sites and ion exchange degree played a decisive role in adjusting the window pore size of RHO zeolites. A comparison of the adsorption equilibrium selectivity reveals that Li-RHO zeolite achieved thermodynamic O2 selective adsorption. In addition, the ideal adsorption solution theory model (IAST) in this study predicts the highest O2/N2 separation performance parameters of Li-RHO zeolite for N2 (79%)/O2 (21%) binary mixtures. Meanwhile, Li-RHO was simulated simultaneously with industrial nitrogen production adsorbents such as 4A and CMS in an Aspen Adsorption two-tower PSA process. The highest product recovery was achieved for Li-RHO at an approximate purity of 92%. Therefore, Li-RHO may be a viable alternative to 4A and CMS in the PSA process, providing new clues for developing O2-selective adsorbents for air separation.

Competition adsorption of CO2/CH4 in shale: Implications for CO2 sequestration with enhanced gas recovery

The competitive adsorption of CO2/CH4 mixtures in shale is a prerequisite for optimizing the process of CO2 sequestration in shale with enhanced gas recovery (CO2-ESGR). In this study, pure and binary adsorption of CH4 and CO2 in shale was measured at pressures up to 13 MPa and the temperature of 323.15 K using volumetric method. Pure and binary adsorption showed that CO2 is preferentially adsorbed in shale, and the adsorption amount of binary CO2/CH4 increased with the increase of CO2 composition. The selectivity factor of CO2 over CH4 (SCO2/CH4) in all the tested samples is greater than 1 and closely related to the pressure and CO2/CH4 concentration, as well as the CO2 phase state. SCO2/CH4 generally decreased with the increase of pressure in the case of 50%CH4 + 50%CO2, while first decreased and then increased with the increase of pressure in the cases of 25%CH4 + 75%CO2 and 75%CH4 + 25%CO2 for most of the tested shale samples. The SCO2/CH4 for most of tested shale samples in the case of 50%CH4 + 50%CO2 is the largest, and the SCO2/CH4 in the case of 75%CH4 + 25%CO2 is greater than that in the case of 25%CH4 + 75%CO2, indicating that the SCO2/CH4 initially increased then decreased with the increase of CO2 fraction. Thus, the CO2 is suggested to be injected when the reservoir pressure reduced to a certain level, and the injection pressure, rate and amount of CO2 should be optimized, to obtain an optimal SCO2/CH4 to improve the efficiency of CO2-ESGR and maximize the CO2 storage capacity. Furthermore, the binary CO2 and CH4 adsorption data were predicted using various models. The Ideal Adsorption Solution Theory (IAST) model fitted the experimental adsorption data the best, followed by the Extended Langmuir (E-L) and Loading Ratio Correlation (LRC). The results provide a firm basis for optimizing the CO2 injection strategies and estimating CO2 storage potential for CO2-ESGR operation.

Developing ordered mesoporous silica superacids for high-precision adsorption and separation of ammonia

NH3 reversible adsorption and separation show great significance during its production and utilization, traditional adsorbents show either complex synthetic procedures or unsatisfied separation precision. We report here a class of sulfonic group functionalized and ordered mesoporous silica superacids (OMS-SO3H-xs) via enhanced host–guest assembly between copolymer templates and silica precursors without additional solvent. The OMS-SO3H-xs have large surface areas (463.7–910.5 m2/g), abundant micropores tandem well-ordered mesopores, high concentration of –SO3H (2.5 mmol/g) with extremely-high acid strength. Consequently, the OMS-SO3H-xs exhibit ultra-high precision for NH3 reversible adsorption and separation, giving high NH3 capacity (9.0 & 7.6 mmol/g at 25 & 50 °C and 1.0 bar) with extraordinary NH3/N2 (0.1/0.9) Ideal Adsorption Solution Theory (IAST) selectivities (1200 & 2235). The room temperature saturated breakthrough NH3 capacities of OMS-SO3H-xs were up to 3.38 mmol/g (3.0v%NH3/24.75v%N2/72.25v%H2), which can be well-maintained after 8th cycling without attenuation. The above features found in the OMS-SO3H-xs were resulted from their high density of –SO3H superacid sites those were homogeneously anchored into the ordered mesoporosity, which not only enhances their interaction with NH3, but also achieves the controllable NH3 interaction and transportation inside the mesochannels.

An ethynyl-modified interpenetrated metal-organic framework for highly efficient selective gas adsorption.

An ethynyl-modified interpenetrated MOF material with lvt topology, [Cu2(BTEB)(NMF)2]·NMF·8H2O (compound 1, H4BTEB = 4,4',4'',4'''-(benzene-1,2,4,5-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid, NMF = N-Methylformamide), was successfully synthesized by using an alkynyl-functionalized H4BTEB organic ligand under solvothermal conditions. Structural analysis shows that compound 1, consisting of a tetradentate carboxylic acid ligand and classical [Cu2(CO2)4] paddle-wheel structure building units, has a rare 4-connected lvt topology with dual interpenetrating structure, which can improve the framework stability, as well as the gas adsorption capacity and selectivity due to the restricted pore channel. According to the study of gas adsorption performance, compound 1 with a larger surface area, boasts a superior adsorption capacity for small gas molecules. Also, ideal adsorption solution theory (IAST) computational simulation shows that compound 1 has good gas adsorption selectivity for C3H8/CH4, indicating its potential application in gas separation.

Characteristics of in situ synthesized activated carbon and metal‐organic framework composites for CH4/N2 gas mixture separation

AbstractIn this study, activated carbon and metal‐organic framework composites were synthesized by in situ hydrothermal method, and the surface morphology, physicochemical structure and adsorption performance of the materials were tested. Moreover, the competitive adsorption characteristics of CH4/N2 gas mixture on the materials MIL‐101, DFAC‐MIL‐101 and NMAC‐MIL‐101 were predicted based on the ideal adsorption solution theory (IAST). Results show that the rod‐like fibers formed after doping with activated carbon did not affect the crystal structure of the metal‐organic framework material but caused the unevenness and passivation of the crystal surface, and the crystal size of MIL‐101 was significantly decreased due to which the micropores of the composite material were more developed, while the mesopores and macropores were decreased accordingly. Meanwhile, the micropore size of MIL‐101 and Ac‐MIL‐101 composite materials were mainly distributed around 0.9, 1.2 and 1.7 nm. The adsorption isotherms of these three materials for CH4 and N2 had typical type I characteristics, and the adsorption selectivity S for binary CH4/N2 gas mixture is greater than 2. Doping activated carbon could properly control the structure of MIL‐101 crystals and improved the selectivity effectively, which provides a certain guiding significance for the structure regulation and application of MIL‐101 metal‐organic framework materials. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

Design of N-doped carbon materials using self-template strategy for high-performance supercapacitor electrodes and CO2 capture

Hierarchical N-doped porous carbons were synthesized using a self-templated and solvent-free assembly approach via directly heating green polyaspartic acid potassium. The samples prepared under different calcining temperatures were characterized, which exhibited the structural features of high pore volume (0.88–1.75 cm 3 /g) and large specific surface area (1592–3133 m 2 /g). Subsequently, these samples were applied for selective CO 2 capture and supercapacitor electrodes. The N-PCM-900 prepared at 900 °C afforded superb electrochemical performance, including extremely large specific capacitance (346 F/g at 1 A/g), high-rate capability (charge-discharge profiles at 20 A/g), and excellent cycle stability (96.86 % retention after 1000 cycles) in KOH electrolyte (6 M). Moreover, N-PCM-900 simultaneously provided high CO 2 adsorption ability (4.63 mmol/g) at 273 K, and high ideal adsorption solution theoretical value (25) for capturing CO 2 /N 2 at 298 K. The multifunctional porous carbon presented herein exhibited great potential for electrochemical energy storage and gas adsorption/separation. • A self-templated and solvent-free assembly approach was developed for the synthesis of hierarchical N-doped porous carbon. • The samples exhibited the structural features of high pore volume (1.75 m 3 g) and large specific surface area (3133 m 2 g). • High specific capacitance (161 F/g) and stability (99.4 % after 1000 cycles) are obtained. • Excellent CO 2 adsorption capacity (4.21 mmol/g) at 273 K and IAST selectivity (25) are gave.

Thiophene-based conjugated ultra-micropore rigid polymers for selective xenon capture

Radioactive isotopes of krypton (Kr) and xenon (Xe) are produced from the fission reaction of nuclear reactors. The separation of Xe/Kr from the nuclear off-gas is important for the spent fuel reprocessing. Compared with the industrial method of cryogenic distillation, physical adsorption is a simple and energy-saving method for Xe/Kr separation. Here, three rigid conjugated micropore polymers, including thiophene containing CMP-PY-BTP, TBTP and fluorine-containing CMP-PY-TFB, were prepared in high yield through direct CH arylation reaction, and their structure–function relationship with Xe/Kr separation was described. CMP-PY-TFB, BTP, and TBTP all possessed rigid micropores with Brunauer-Emmett-Teller specific surface areas of 786.25, 141.64 and 488.30 m2/g, respectively. Among three polymers, CMP-PY-TBTP exhibited the highest Xe/Kr selectivity (11.9 for ideal adsorption solution theory selectivity and 9.3 for Henry selectivity), owing to the combined effect of stronger polarization of its thiophene structural unit and micropore confinement (5.4 Å). The density functional theory (DFT) calculation revealed that Xe was more strongly adsorbed in thiophene-containing units than that of fluorine-containing unit which verified the stronger interaction caused by thiophene group’s polarization. Though having weaker polarization to Xe, fluorine-containing CMP-PY-TFB exhibited the highest Xe uptake of 43.59 cm3 g−1 due to its largest specific surface area (786.25 m2/g).

Exploring the Potential of Metal-Organic Frameworks for the Separation of Blends of Fluorinated Gases with High Global Warming Potential.

The research on porous materials for the selective capture of fluorinated gases (F-gases) is key to reduce their emissions. Here, the adsorption of difluoromethane (R-32), pentafluoroethane (R-125), and 1,1,1,2-tetrafluoroethane (R-134a) is studied in four metal-organic frameworks (MOFs: Cu-benzene-1,3,5-tricarboxylate, zeolitic imidazolate framework-8, MOF-177, and MIL-53(Al)) and in one zeolite (ZSM-5) with the aim to develop technologies for the efficient capture and separation of high global warming potential blends containing these gases. Single-component sorption equilibria of the pure gases are measured at three temperatures (283.15, 303.15, and 323.15K) by gravimetry and correlated using the Tóth and Virial adsorption models, and selectivities toward R-410A and R-407F are determined by ideal adsorption solution theory. While at lower pressures, R-125 and R-134a are preferentially adsorbed in all materials, at higher pressures there is no selectivity, or it is shifted toward the adsorption R-32. Furthermore, at high pressures, MOF-177 shows the highest adsorption capacity for the three F-gases. The results presented here show that the utilization of MOFs, as tailored made materials, is promising for the development of new approaches for the selective capture of F-gases and for the separation of blends of these gases, which are used in commercial refrigeration.

One-Pot Synthesis of N-Rich Porous Carbon for Efficient CO2 Adsorption Performance.

N-enriched porous carbons have played an important part in CO2 adsorption application thanks to their abundant porosity, high stability and tailorable surface properties while still suffering from a non-efficient and high-cost synthesis method. Herein, a series of N-doped porous carbons were prepared by a facile one-pot KOH activating strategy from commercial urea formaldehyde resin (UF). The textural properties and nitrogen content of the N-doped carbons were carefully controlled by the activating temperature and KOH/UF mass ratios. As-prepared N-doped carbons show 3D block-shaped morphology, the BET surface area of up to 980 m2/g together with a pore volume of 0.52 cm3/g and N content of 23.51 wt%. The optimal adsorbent (UFK-600-0.2) presents a high CO2 uptake capacity of 4.03 mmol/g at 0 °C and 1 bar. Moreover, as-prepared N-doped carbon adsorbents show moderate isosteric heat of adsorption (43–53 kJ/mol), acceptable ideal adsorption solution theory (IAST) selectivity of 35 and outstanding recycling performance. It has been pointed out that while the CO2 uptake was mostly dependent on the textural feature, the N content of carbon also plays a critical role to define the CO2 adsorption performance. The present study delivers favorable N-doped carbon for CO2 uptake and provides a promising strategy for the design and synthesis of the carbon adsorbents.