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1.
Utilization of porous materials for gas capture and separation is a hot research topic. Removal of acetylene (C 2H 2) from ethylene (C 2H 4) is important in the oil refining and petrochemical industries, since C 2H 2 impurities deactivate the catalysts and terminate the polymerization of C 2H 4. Carbon dioxide (CO 2) emission from power plants contributes to global climate change and threatens the survival of life on this planet. Herein, 2D crystalline polyimide porous organic framework PAF-120, which was constructed by imidization of linear naphthalene-1,4,5,8-tetracarboxylic dianhydride and triangular 1,3,5-tris(4-aminophenyl)benzene, showed significant thermal and chemical stability. Low-pressure gas adsorption isotherms revealed that PAF-120 exhibits good selective adsorption of C 2H 2 over C 2H 4 and CO 2 over N 2. At 298 K and 1 bar, its C 2H 2 and CO 2 selectivities were predicted to be 4.1 and 68.7, respectively. More importantly, PAF-120 exhibits the highest selectivity for C 2H 2/C 2H 4 separation among porous organic frameworks. Thus PAF-120 could be a suitable candidate for selective separation of C 2H 2 over C 2H 4 and CO 2 over N 2. 相似文献
2.
Light hydrocarbon separation is considered one of the most industrially challenging and desired chemical separation processes and is highly essential in polymer and chemical industries. Among them, separating ethylene (C 2H 4) from C2 hydrocarbon mixtures such as ethane (C 2H 6), acetylene (C 2H 2), and other natural gas elements (CO 2, CH 4) is of paramount importance and poses significant difficulty. We demonstrate such separations using an Al-MOF synthesised earlier as a non-porous material, but herein endowed with hierarchical porosity created under microwave conditions in an equimolar water/ethanol solution. The material possessing a large surface area (793 m 2 g −1) exhibits an excellent uptake capacity for major industrial hydrocarbons in the order of C 2H 2 > C 2H 6 > CO 2 > C 2H 4 > CH 4 under ambient conditions. It shows an outstanding dynamic breakthrough separation of ethylene (C 2H 4) not only for a binary mixture (C 2H 6/C 2H 4) but also for a quaternary combination (C 2H 4/C 2H 6/C 2H 2/CO 2 and C 2H 4/C 2H 6/C 2H 2/CH 4) of varying concentrations. The detailed separation/purification mechanism was unveiled by gas adsorption isotherms, mixed-gas adsorption calculations, selectivity estimations, advanced computer simulations such as density functional theory (DFT), grand canonical Monte Carlo (GCMC) and ab initio molecular dynamics (AIMD), and stepwise multicomponent dynamic breakthrough experiments.Industrially important C 2H 4 purification from multi-component hydrocarbon mixtures. 相似文献
3.
Selective-adsorption separation is an energy-efficient technology for the capture of acetylene (C 2H 2) from carbon dioxide (CO 2) and ethylene (C 2H 4). However, it remains a critical challenge to effectively recognize C 2H 2 among CO 2 and C 2H 4, owing to their analogous molecule sizes and physical properties. Herein, we report a new microporous metal–organic framework (NUM-14) possessing a carefully tailored pore system containing moderate pore size and nitro-functionalized channel surface for efficient separation of C 2H 2 from CO 2 and C 2H 4. The activated NUM-14 (namely NUM-14a) exhibits sufficient pore space to acquire excellent C 2H 2 loading capacity (4.44 mmol g −1) under ambient conditions. In addition, it possesses dense nitro groups, acting as hydrogen bond acceptors, to selectively identify C 2H 2 molecules rather than CO 2 and C 2H 4. The breakthrough experiments demonstrate the good actual separation ability of NUM-14a for C 2H 2/CO 2 and C 2H 2/C 2H 4 mixtures. Furthermore, Grand Canonical Monte Carlo simulations indicate that the pore surface of the NUM-14a has a stronger affinity to preferentially bind C 2H 2 over CO 2 and C 2H 4 via stronger C-H···O hydrogen bond interactions. This article provides some insights into customizing pore systems with desirable pore sizes and modifying groups in terms of MOF materials toward the capture of C 2H 2 from CO 2 and C 2H 4 to promote the development of more MOF materials with excellent properties for gas adsorption and separation. 相似文献
4.
The NIIC-20 (NIIC stands for Nikolaev Institute of Inorganic Chemistry) is a family of five isostructural metal-organic frameworks (MOFs) based on dodecanuclear wheel-shaped carboxylate building blocks {Zn 12(RCOO) 12(glycol) 6} (glycol is deprotonated diatomic alcohol: ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol or glycerol), quantitatively crystallized from readily available starting chemicals. The crystal structures contain large mesoporous cages of 25 Å connected through {Zn 12} rings, of which inner diameter and chemical nature depend solely on the chosen glycol. The NIIC-20 compounds feature high surface area and rarely observed inversed adsorption affinity for saturated hydrocarbon (ethane) over the unsaturated ones (ethylene, acetylene). The corresponding IAST (Ideal Adsorbed Solution Theory) adsorption selectivity factors reach as much as 15.4 for C 2H 6/C 2H 4 and 10.9 for C 2H 6/C 2H 2 gas mixtures at ambient conditions, exceeding those for any other porous MOF reported so far. The remarkable combination of high adsorption uptakes and high adsorption selectivities makes the NIIC-20 series a new benchmark of porous materials designed for ethylene separation applications. 相似文献
5.
Activated carbon (AC) supported CuCl (CuCl/AC) for ethylene/ethane separation has been prepared with CuCl 2 as precursor by a solid-state dispersion method. The samples are characterized by inductively coupled plasma optical emission spectrometry, X-ray diffraction, N 2 adsorption/desorption and X-ray photoelectron spectroscopy, and investigated for ethylene (C 2H 4) and ethane (C 2H 6) adsorptions. The characterization results reveal that CuCl 2 supported on AC can be highly dispersed on the surfaces of AC support and completely converted to CuCl after activation at 543 K in N 2. The resultant adsorbent displays high ethylene adsorption capacity, high C 2H 4/C 2H 6 adsorption selectivity and excellent reversibility. The adsorption isotherms of ethylene and ethane on CuCl/AC at temperatures up to 333 K can be well fitted by the Sips models, and the corresponding isosteric heats of adsorption are calculated from the Clausius–Clapeyron equation. The value of isosteric heat of adsorption suggests that the interaction of ethylene with CuCl/AC is between physisorption and chemisorption. 相似文献
6.
Developing adsorptive separation processes based on C 2H 6-selective sorbents to replace energy-intensive cryogenic distillation is a promising alternative for C 2H 4 purification from C 2H 4/C 2H 6 mixtures, which however remains challenging. During our studies on two isostructural metal–organic frameworks ( Ni-MOF 1 and Ni-MOF 2 ), we found that Ni-MOF 2 exhibited significantly higher performance for C 2H 6/C 2H 4 separation than Ni-MOF-1 , as clearly established by gas sorption isotherms and breakthrough experiments. Density-Functional Theory (DFT) studies showed that the unblocked unique aromatic pore surfaces within Ni-MOF 2 induce more and stronger C−H⋅⋅⋅π with C 2H 6 over C 2H 4 while the suitable pore spaces enforce its high C 2H 6 uptake capacity, featuring Ni-MOF 2 as one of the best porous materials for this very important gas separation. It generates 12 L kg −1 of polymer-grade C 2H 4 product from equimolar C 2H 6/C 2H 4 mixtures at ambient conditions. 相似文献
7.
Storage and separation of small (C1–C3) hydrocarbons are of great significance as these are alternative energy resources and also can be used as raw materials for many industrially important materials. Selective capture of greenhouse gas, CO 2 from CH 4 is important to improve the quality of natural gas. Among the available porous materials, MOFs with permanent porosity are the most suitable to serve these purposes. Herein, a two‐fold entangled dynamic framework {[Zn 2(bdc) 2(bpNDI)]?4DMF} n with pore surface carved with polar functional groups and aromatic π clouds is exploited for selective capture of CO 2, C2, and C3 hydrocarbons at ambient condition. The framework shows stepwise CO 2 and C 2H 2 uptake at 195 K but type I profiles are observed at 298 K. The IAST selectivity of CO 2 over CH 4 is the highest (598 at 298 K) among the MOFs without open metal sites reported till date. It also shows high selectivity for C 2H 2, C 2H 4, C 2H 6, and C 3H 8 over CH 4 at 298 K. DFT calculations reveal that aromatic π surface and the polar imide (RNC=O) functional groups are the primary adsorption sites for adsorption. Furthermore, breakthrough column experiments showed CO 2/CH 4 C 2H 6/CH 4 and CO 2/N 2 separation capability at ambient condition. 相似文献
8.
Adsorptive separation is an energy-efficient alternative, but its advancement has been hindered by the challenge of industrially potential adsorbents development. Herein, a novel ultra-microporous metal-organic framework ZU-901 is designed that satisfies the basic criteria raised by ethylene/ethane (C 2H 4/C 2H 6) pressure swing adsorption (PSA). ZU-901 exhibits an “S” shaped C 2H 4 curve with high sorbent selection parameter (65) and could be mildly regenerated. Through green aqueous-phase synthesis, ZU-901 is easily scalable with 99 % yield, and it is stable in water, acid, basic solutions and cycling breakthrough experiments. Polymer-grade C 2H 4 (99.51 %) could be obtained via a simulating two-bed PSA process, and the corresponding energy consumption is only 1/10 of that of simulating cryogenic distillation. Our work has demonstrated the great potential of pore engineering in designing porous materials with desired adsorption and desorption behavior to implement an efficient PSA process. 相似文献
9.
Two C 2H 6-selective metal-organic framework (MOF) adsorbents with ultrahigh stability, high surface areas, and suitable pore size have been designed and synthesized for one-step separation of ethane/ethylene (C 2H 6/C 2H 4) under humid conditions to produce polymer-grade pure C 2H 4. Experimental results reveal that these two MOFs not only adsorb a high amount of C 2H 6 but also display good C 2H 6/C 2H 4 selectivity verified by fixed bed column breakthrough experiments. Most importantly, the good water stability and hydrophobic pore environments make these two MOFs capable of efficiently separating C 2H 6/C 2H 4 under humid conditions, exhibiting the benchmark performance among all reported adsorbents for separation of C 2H 6/C 2H 4 under humid conditions. Moreover, the affinity sites and their static adsorption energies were successfully revealed by single crystal data and computation studies. Adsorbents described in this work can be used to address major chemical industrial challenges. 相似文献
10.
Low-concentration ethane capture is crucial for environmental protection and natural gas purification. The ideal physisorbent with strong C 2H 6 interaction and large C 2H 6 uptake at low-concentration level has rarely been reported, due to the large p Ka value and small quadrupole moment of C 2H 6. Herein, we demonstrate the perfectly size matching between the ultramicropore (pore size of 4.6 Å) and ethane (kinetic diameter of 4.4 Å) in a nickel pyridine-4-carboxylate metal–organic framework (IISERP-MOF 2 ), which enables the record-breaking performance for low concentration C 2H 6 capture. IISERP-MOF 2 exhibits the large C 2H 6 adsorption enthalpy of 56.7 kJ/mol, and record-high C 2H 6 uptake at low pressure of 0.01–0.1 bar and 298 K (1.8 mmol/g at 0.01 bar). Molecule simulations and C 2H 6-loading crystal structure analysis revealed that the maximized interaction sites in IISERP-MOF 2 with ethane molecule originates the strong C 2H 6 adsorption. The dynamic breakthrough experiments for gas mixtures of C 2H 6/N 2(1/999, v/ v) and C 2H 6/CH 4 (5/95, v/ v) proved the excellent low-concentration C 2H 6 capture performance. 相似文献
11.
Endohedral adsorption properties of ethylene and ethane onto single-walled carbon nanotubes were investigated using a united
atom (2CLJQ) and a fully atomistic (AA-OPLS) force fields, by Grand Canonical Monte Carlo and Molecular Dynamics techniques.
Pure fluids were studied at room temperature, T=300 K, and in the pressure ranges 4×10 −4< p<47.1 bar (C 2H 4) and 4×10 −4< p<37.9 bar (C 2H 6). In the low pressure region, isotherms differ quantitatively depending on the intermolecular potential used, but show the
same qualitative features. Both potentials predict that ethane is preferentially adsorbed at low pressures, and the opposite
behavior was observed at high loadings. Isosteric heats of adsorption and estimates of low pressure Henry’s constants, confirmed
that ethane adsorption is the thermodynamically favored process at low pressures. Binary mixtures of C 2H 4/C 2H 6 were studied under several ( p, T) conditions and the corresponding selectivities towards ethane, S, were evaluated. Small values of S<4 were found in all cases studied. Nanotube geometry plays a minor role on the adsorption properties, which seem to be driven
at lower pressures primarily by the larger affinity of the alkane towards the carbon surface and at higher pressures by molecular
volume and packing effects. The fact that the selectivity towards ethane is similar to that found earlier on carbon slit pores
and larger diameter nanotubes points to the fact that the peculiar 1-D geometry of the nanotubes provides no particular incentive
for the adsorption of either species. 相似文献
12.
Dichlorosilane is a flammable and poisonous gas which is very toxic when inhaled. When handling this gas, extreme precautions must be taken to prevent exposure and so therefore there is need to develop a more sensitive and affordable sensor to detect and measure the concentration of gas in the environment in case of unintentional release of the gas into the air. Overtime, structured materials have been used in the adsorption of target gas. Herein, the detection of dichlorosilane (H 2SiCl 2) gas by transition metals (X = Cr, Fe, Ni, Ti, and Zn) anchored fullerene is studied using the density functional theory (DFT) computation at theωB97X-D/gen/6-311++G(d,p)/LanL2DZ level of theory. From the electronic properties, large energy gap signifies lower electrical conductivity and sensitivity. The result showed an increase in the energy gap on adsorption of the gas on nanocages except for N1 and T1 where the energy gap was lesser than that of the nanocages. Calculations shows among the five studied surfaces, C 23–Ti surface emerged with the highest adsorption energy value of ?2.231 eV and corresponding energy gap value of 5.200 eV. Also, the decreasing trend of adsorption energies: H 2Cl 2SiC 23Ti ( T1), (?2.231) > H 2SiCl 2C 23Ni ( N1), (?2.095) > H 2SiCl 2C 23Zn ( Z1) (?2.068) > H 2SiCl 2C 23Cr ( C1) (?1.796) > H 2SiCl 2C 23Fe ( F1) (?1.742) was observed. High negative value of adsorption energy, the lesser the recovery time. H 2Cl 2SiC 23Ti ( T1) complex with high negative value of adsorption energy has a lesser recovery time exhibits better sensing attributes. The C 23–Ti surface is relatively a better candidate in the adsorption and, hence, confirmed as suitable nanosensor material for the detection and adsorption of toxic dichlorosilane (H 2SiCl 2) gas molecule. 相似文献
13.
In this study, in order to consider the effect of the time of the nitric acid treatment on thermal, structural and gas adsorption properties, clinoptilolite was modified with 1.0 M acid solutions at 80 °C for 2, 4, 6, 12 and 24 h. Structural and thermal properties of natural and acid-treated clinoptilolites were investigated by powder X-ray diffraction, X-ray fluorescence, thermogravimetric analysis, differential thermal analysis and nitrogen adsorption methods. Methane (CH4) and ethylene (C2H4) are hazardous gases for human and plant health, respectively. Therefore, some measures should be taken to reduce emissions of methane and ethylene. CH4 and C2H4 adsorption capacities of clinoptilolite (CLN) from Turkey and that of acid-treated forms at 273 K up to 100 kPa were found between 0.556–0.683 and 0.470–1.295 mmol g?1, respectively. 相似文献
14.
The separation of C 2H 2 from C 2H 4 is one of the most challenging tasks due to the similarity of their physical properties. In addition, green synthetic protocol and adsorbent's stability are also the major concerns during the separation. Herein, under hydrothermal green synthesis conditions, an ultrastable ultramicroporous Zn-MOF was designed and synthesized with a high yield. The pore diameter of the Zn-MOF is 3.6 Å, which lies in between the diameters of C 2H 2 (3.3 Å) and C 2H 4 (4.2 Å) molecules, leading to an efficient separation of the C 2H 2/C 2H 4 mixtures by the sieving effect. The practical separation performance of C 2H 2/C 2H 4 was confirmed by the dynamic breakthrough experiments. Moreover, the high stability enables the adsorption capacity of the Zn-MOF to C 2H 2, which can be maintained under a wide range of pH (1–13). Molecular simulations were also performed to identify the different C 2H 2- and C 2H 4-binding sites in Zn-MOF. 相似文献
15.
Four 4,4′-bipyridine α,ω-dicarboxylate coordination polymers Cu(bpy)(C 5H 6O 4) ( 1), Zn(bpy)(C 5H 6O 4) ( 2), Zn(bpy)(C 6H 8O 4) ( 3) and Mn(bpy)(C 8H 12O 4) · H 2O ( 4) have been synthesized and structurally characterized by single crystal X-ray diffraction methods (bpy = 4,4-bipyridine, (C 5H 6O 4) 2− = glutarate anion, (C 6H 8O 4) 2− = adipate anion, (C 8H 12O 4) 2− = suberate anion). Their crystal structures are featured by dimeric metal units, which are co-bridged by 4,4′-bipyridine ligands and dicarboxylate anions such as glutarate, adipate and suberate anions to generate 2D layers with a (4,4) topology in 1, 2 and 4 as well as to form 3D frameworks in 3. Two 3D frameworks in 3 interpenetrate with each other to form a topology identical to the well-known Nb 6F 15 cluster compound. Over 5–300 K, the paramagnetic behavior of 4 follows the Curie–Weiss law χm( T − Θ) = 4.265(5) cm 3 mol −1 with the Weiss constant Θ = −6.3(2) K. Furthermore, the thermal behavior of 3 and 4 is also discussed. 相似文献
16.
Gas separation efficiency of covalent organic framework (COF) membrane can be greatly elevated through precise functionalization. A pair-functionalized COF membrane of 1,3,5-triformylphloroglucinol (TP) and isoquinoline-5,8-diamine (IQD) monomers in two and three nodes is designed and synthesized. TP-IQD is crystallized in a two-dimensional structure with a pore size of 6.5 Å and a surface area of 289 m 2 g −1. This COF possesses N−O paired groups which cooperatively interact with C 2H 2 instead of C 2H 4. TP-IQD nanosheets of ≈10 μm in width and ≈4 nm in thickness are prepared by mechanical exfoliation; they are further processed with 6FDA-ODA polymer into a hybrid membrane. High porosity and functionality pair of TP-IQD offer the membrane with significantly increased C 2H 2 permeability and C 2H 2/C 2H 4 selectivity which are 160 % and 430 % higher of pure 6FDA-ODA. The boosted performance demonstrates high efficiency of the pair-functionality strategy for the synthesis of separation-led COFs. 相似文献
17.
Adsorptive separation of acetylene (C 2H 2) from carbon dioxide (CO 2) is of great significance in petrochemical industry, but still remains as a daunting challenge by reason of their very similar molecular sizes/shapes and physical properties. Herein, we reported a new perchlorate-based hybrid ultramicroporous material ZJU-194 that features the unique flexible-robust network decorated with rich bare oxygen atoms. By integrating the refined pore space as well as specific binding sites, the activated ZJU-194 (ZJU-194a) enables a selective two-step gate-opening adsorption toward C 2H 2, but blocks off the further uptake of CO 2. It thus exhibits a very high C 2H 2/CO 2 selectivity (22.4) at ambient conditions, which is superior to most reported MOF materials. Its complete separation for 50/50 C 2H 2/CO 2 mixtures is further evidenced by the dynamic breakthrough experiments. 相似文献
18.
The separation of acetylene from ethylene is a crucial process in the petrochemical industry, because even traces of acetylene impurities can poison the catalysts of ethylene polymerization. Herein, we synthesize a new family of 3D porous aromatic frameworks (PAFs), non-functionalized PAF-28, carbene-functionalized PAF-28 (cPAF-28) and imidazolium-functionalized PAF-28 (iPAF-28), via Sonogashira coupling reactions. These PAFs show high porosity and good thermal stability. Both cPAF-28 and iPAF-28 are proved to be good candidates for C 2H 2 adsorption, demonstrated by C 2H 2/C 2H 4 selectivity of 12.2 and 15.4, and C 2H 2 capacity of 48 cm 3 g −1 and 57 cm 3 g −1, which are significantly higher than those of non-functionalized PAF-28 (1.8, 37 cm 3 g −1). Furthermore, the cPAF-28 and iPAF-28 display good breakthrough performance and remarkable recyclability for the separation of the C 2H 2/C 2H 4 gas mixture. In addition, the C 2H 2/C 2H 4 adsorption sites are revealed by DFT calculations. This work sheds a new light on gas molecular recognition by tailoring the pore chemistry of PAFs.A family of PAFs with 3D topology was developed through tailoring the pore structures. By anchoring carbene or imidazolium groups in PAF-28, the selectivity for separating acetylene from ethylene was greatly boosted from 1.8 to 15.4. 相似文献
19.
Force‐field based grand‐canonical Monte Carlo simulations are used to investigate the acetylene and carbon dioxide uptake capacity, as well as the C2H2/CO2 adsorption selectivity of three novel microporous materials: Magnesium formate, Cu3(btc)2, and cucurbit[6]uril. Because no comparable computational studies of acetylene adsorption have been reported so far, the study focuses on systems for which experimental data are available to permit a thorough validation of the simulation results. The results for magnesium formate are in excellent agreement with experiment. The simulation predicts a high selectivity for acetylene over CO2, which can be understood from a detailed analysis of the structural features that determine the affinity of Mg‐formate towards C2H2. For Cu3(btc)2, preliminary calculations reveal the necessity to include the interaction of the sorbate molecules with the unsaturated metal sites, which is done by means of a parameter adjustment based on ab‐initio calculations. In spite of the high C2H2 storage capacity, the C2H2/CO2 selectivity of this material is very modest. The simulation results for the porous organic crystal cucurbit[6]uril show that the adsorption characteristics that have been observed experimentally, particularly the very high isosteric heat of adsorption, cannot be understood when an ideal structure is assumed. It is postulated that structural imperfections play a key role in determining the C2H2 adsorption behavior of this material, and this proposition is supported by additional calculations. 相似文献
20.
An anionic multifunctional porous metal organic framework (MOF), [Cu 2THBA(H 2O) 2] · (C 3H 7NO) 12 · (H 2O) 10 ( 1 ) (H 4THBA = p‐terphenyl‐3,2′′,3′′,5,5′′,5′′′‐ hexcarboxylic acid) with NbO‐type topology was synthesized and characterized. Due to multiple functional sites and suitable pore size, the desolvated compound 1a exhibits high separation selectivity for C 2H 2/CO 2 of 30 and C 2H 2/CH 4 of 131 at 1 kPa at room temperature. Compound 1 can also efficiently and completely separate methylene blue (MB +) molecules of low concentrations from aqueous solution in 12 h. 相似文献
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