Home Journals Articles Updates About
CN
image
收藏切换
Single-Molecule Traps in Covalent Organic Frameworks for Selective Capture of C2H2 from C2H4-Rich Gas Mixtures
收藏切换
PDF
Yilun Zhou1, Yinghui Xie1, Xiaolu Liu1, Mengjie Hao1, Zhongshan Chen1, Hui Yang1, *, Geoffrey I. N. Waterhouse2, Shengqian Ma3, *, Xiangke Wang1, *
Research. Vol 7 Article ID 0458
Less
收藏切换
Research. Vol 7 Article ID 0458
• Research Article •
Single-Molecule Traps in Covalent Organic Frameworks for Selective Capture of C2H2 from C2H4-Rich Gas Mixtures
Full
Yilun Zhou1, Yinghui Xie1, Xiaolu Liu1, Mengjie Hao1, Zhongshan Chen1, Hui Yang1, *, Geoffrey I. N. Waterhouse2, Shengqian Ma3, *, Xiangke Wang1, *
Affiliations
  • 1College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, P.R. China.
  • 2MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical Sciences, The University of Auckland, Auckland 1142, New Zealand.
  • 3Department of Chemistry, University of North Texas, Denton, TX 76201, USA.
Published: 2024-08-26 doi: 10.34133/research.0458
Outline
收藏切换

Removing trace amounts of acetylene (C2H2) from ethylene (C2H4)-rich gas mixtures is vital for the supply of high-purity C2H4 to the chemical industry and plastics sector. However, selective removal of C2H2 is challenging due to the similar physical and chemical properties of C2H2 and C2H4. Here, we report a “single-molecule trap” strategy that utilizes electrostatic interactions between the one-dimensional (1D) channel of a covalent organic framework (denoted as COF-1) and C2H2 molecules to massively enhance the adsorption selectivity toward C2H2 over C2H4. C2H2 molecules are immobilized via interactions with the O atom of C=O groups, the N atom of C≡N groups, and the H atom of phenyl groups in 1D channels of COF-1. Due to its exceptionally high affinity for C2H2, COF-1 delivered a remarkable C2H2 uptake of 7.97 cm3/g at 298 K and 0.01 bar, surpassing all reported COFs and many other state-of-the-art adsorbents under similar conditions. Further, COF-1 demonstrated outstanding performance for the separation of C2H2 and C2H4 in breakthrough experiments under dynamic conditions. COF-1 adsorbed C2H2 at a capacity of 0.17 cm3/g at 2,000 s/g when exposed to 0.5 ml/min C2H4-rich gas mixture (99% C2H4) at 298 K, directly producing high-purity C2H4 gas at a rate of 3.95 cm3/g. Computational simulations showed that the strong affinity between C2H2 and the single-molecule traps of COF-1 were responsible for the excellent separation performance. COF-1 is also robust, providing a promising new strategy for the efficient removal of trace amounts of C2H2 in practical C2H4 purification.

Yilun Zhou, Yinghui Xie, Xiaolu Liu, Mengjie Hao, Zhongshan Chen, Hui Yang, Geoffrey I. N. Waterhouse, Shengqian Ma, Xiangke Wang. Single-Molecule Traps in Covalent Organic Frameworks for Selective Capture of C2H2 from C2H4-Rich Gas Mixtures[J]. Research, 2024 , 7 (8) : 0458 . DOI: 10.34133/research.0458
Full Text
Less
Introduction
Less
Ethylene (C2H4) is the most important product in the petrochemical industry, finding widespread use in the manufacture of organic chemicals and polymers [1,2]. However, industrial C2H4 production processes, such as alkane dehydrogenation and naphtha cracking, typically create trace amounts of acetylene (C2H2) as a by-product [1]. Removal of C2H2 from C2H4 feedstocks is of enormous economic and practical importance, since trace C2H2 can adversely impact polymerizations and synthetic applications that require high-purity C2H4 [3,4]. Cryogenic distillation (also known as low-temperature rectification) is a widely used commercial separation process involving liquefying gas mixtures at very low temperatures (183 to 258 K with 7 to 28 bar) and then selectively distilling a specific gas component at its boiling point [5]. This method is frequently applied to separate C2H2 and C2H4, but is expensive and energy intensive. To avoid such high-energy consumption and operating costs, physical adsorption methods using porous solid adsorbent have been widely explored in recent years. Porous materials such as zeolites [6,7], carbons [8,9], and MXenes [10,11] have all been studied as adsorbents to remove C2H2 from C2H4-rich gas mixtures, but their separation processes are generally unsatisfactory due to poor selectivity and a low adsorption capacity. Metal-organic frameworks (MOFs) demonstrate promise in C2H2/C2H4 separations, but suffer stability issues [12–19].
Recently, covalent organic frameworks (COFs) have garnered a great deal of attention for hydrocarbon separations, such as CO2/CH4 [20–26], C2H4/C2H6 [27–32], and C2H4/C3H6 [33], due to their diverse structures, high specific surface areas, programmable pore characteristics, high stability, and other features [34]. Taking advantages of the COF framework's differing affinity for C2H2 and C2H4, COFs have been designed to separate C2H2 from C2H4 [35–41]. However, few studies relating to the dynamic removal of trace amounts of C2H2 from C2H4-rich gas mixtures have been reported [2]. Jiang and co-workers [41] described a robust porous aromatic framework (PAF-110), which exhibited a moderate C2H2 selectivity of 3.9 at 298 K and 1 bar. Next, Wang and co-workers [29] utilized a modulator-assisted strategy to control the interlayer stacking in an imide-linked 2D COF. As-synthesized ABC stacking COF led to a 60% increase in volumetric C2H2 uptake compared with the AA stacking. Subsequently, an olefin-linked COF was synthesized, with a pore size and chemical environment suitable for trapping C2H2 preferentially over C2H4 [42]. These pioneering works take advantage of the pore size, pore dimensions, and location of electron-donating atoms (such as N and O) to selectively coordinate C2H2, thus achieving good separation of C2H2 and C2H4. However, many other factors affect the separation efficiency of C2H2 and C2H4, with the specific nature of the interactions between the guest gas molecules and host adsorption sites in COFs being poorly understood at a molecular level, warranting further exploration. Furthermore, achieving a high separation efficiency at low pressures is typically challenging for COFs. Therefore, it is of great importance to discover COF-based adsorbents capable of separating C2H2 and C2H4 under practical conditions, especially at low C2H2 pressures.
The distribution of electron clouds in C2H2 gives the molecule positive–negative–positive electronegativity and high rotational symmetry along its molecular axis (Fig. 1A and Table S1). The same rotational symmetry does not exist in the C2H4 molecule. As such, the charge distribution along the C–H bonds in C2H4 is not as extreme as in C2H2 (Fig. 1B and Table S1). We believe that suitable adsorption sites can strengthen the separate effect [43]. Based on the differences in electropositivity at the hydrogen atoms in each molecule, we designed and synthesized a robust COF (denoted as COF-1) for the selective separation of C2H2 and C2H4. Owing to the action of C=O, C≡N, and C–H (from the phenyl ring) in the framework, which acted synergistically to form single-molecule traps for C2H2, COF-1 exhibited a record-high static C2H2 adsorption capacity (7.97 cm3/g) at 298 K at ultralow pressures (0.01 bar), outperforming all previously reported COF adsorbents. Dynamic breakthrough experiments showed that COF-1 takes up 0.17 cm3/g of C2H2 at 2,000 s/g in a C2H2/C2H4 = 1:99 (v/v) gas mixture at 298 K. This enables the direct production of 3.95 cm3/g (0.27 ml/min/g) high-purity C2H4 gas under 0.5 ml/min inlet C2H4-rich gas mixture (99% C2H4) at 298 K and 1 bar, comparable to other state-of-the-art adsorbents. Molecular simulations based on the grand canonical Monte Carlo (GCMC), together with first-principles density functional theory (DFT) calculations, revealed that lone pairs of sp hybridized nitrogen atoms in C≡N groups and lone pairs of sp2 hybridized oxygen atoms in C=O groups in the COF-1 framework exhibited negative potentials, while the H atoms in phenyl ring in the framework exhibited positive potentials, with the resulting negative(δ−)–positive(δ+)–negative(δ−) charge distribution being perfect for trapping positive(δ+)–negative(δ−)–positive(δ+) charged C2H2 (Fig. 1C and D). In contrast, C2H4 exhibited a relatively low affinity for the single-molecule traps in COF-1, as expected owing to the differing structure, size, and charge arrangement in C2H4 (Fig. 1C and D). The structure–property relationships developed in this work allowed us to pinpoint the factors influencing binding affinity of COF-1 toward each gas molecule and ultimately explain the C2H2/C2H4 separation performance, guiding the future design of COF-based adsorbents with multiple cooperative functionalities for selective gas separations.
Results and Discussion
Less
COF synthesis and characterization
We proposed that “single-molecule traps” could be used to remove trace amounts of C2H2 in C2H2/C2H4 gas mixtures. For this purpose, we first synthesized COF-1 by reacting 1,3,5-triformylphloroglucinol (Tp) and 2,5-diaminobenzonitrile (Db) in a mixture of mesitylene/1,4-dioxane/acetic acid at 120 °C for 72 h. The Fourier transform infrared (FT-IR) spectrum of COF-1 showed the disappearance of the -CHO groups of Tp at 1,644 cm−1 and -NH2 groups of Db signal at 3,348 cm−1, indicating the successful Schiff-base condensation between Tp and Db (Fig. 2A) [44,45]. No C=N signals were observed, but an intense C=O···H stretch around 1,587 cm−1 appeared due to imine groups transformed to β-ketamine moieties in COF-1. The COF-1 product also showed an absorption peak at 2,225 cm−1 due to C≡N stretching of cyano groups on the aromatic rings of the Db linker (Fig. 2A) [46]. The cyano groups were thus retained with the formation of COF-1. The thermogravimetric analysis (TGA) demonstrated that COF-1 displayed ~10% weight loss up to approximately 400 °C under a N2 atmosphere, suggesting good thermostability (Fig. S1). The crystalline structure of COF-1 was further experimentally and theoretically determined by powder x-ray diffraction (PXRD), small-angle X-ray scattering (SAXS), and theoretical simulations. The experimental PXRD pattern (SAXS used for zero-shift correction) showed diffraction peaks at 2θ angle around 4.4°, 7.9°, 8.9°, and 26.8°, which could be assigned to the (100), (110), (200), and (001) planes, respectively (Fig. 2B). Pawley refinements were performed on the experimental PXRD data to yield unit cell parameters of a = b = 23.29 Å, c = 3.49 Å, α = β = 90°, γ = 120° (residuals Rp = 3.24% and Rwp = 4.19%) for COF-1 (Table S2). The eclipsed stacking (AA) mode was constructed with the unit cell parameter described above to generate a simulated diffraction pattern for comparison with the experimental data. The experimental and simulated data matched well, showing a 3.5-Å layer spacing (Fig. 2C). The hexagonal pore diameter is around ~1.8 nm (Fig. 2C).
N2 sorption isotherms were measured at 77 K for COF-1 to investigate its porosity (Fig. 2D and Fig. S2). The adsorption–desorption isotherms showed type I/IV curves, which suggested microporous structures. The Brunauer–Emmett–Teller (BET) surface area and total pore volume of COF-1 were determined to be 997 m2/g and 0.71 cm3/g, respectively. The pore size analysis revealed that the average pore diameter is ~1.89 nm, well in line with the predicted pore diameter for AA stacking geometries of the framework (Fig. 2E). The scanning electron microscopy (SEM) image of COF-1 showed a flower-like morphology composed of nanorods (Fig. 2F). The transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images confirmed the flower-like morphology, with lattice fringe spacings of 1.96 nm (corresponding to 100 lattice plane) consistent with the porous structures measured by PXRD analysis (Fig. S3).
To validate the utility of using the O atom of C=O, N atom of C≡N, and H atom of phenyl rings to create “single-molecule traps” for separation of C2H2/C2H4, we also synthesized structural analogs (COF-2 and COF-3) for comparison. The synthesis and characterization data for COF-2 and COF-3 are provided in Fig. 2G to J and the Supplementary Materials (Tables S3 and S4 and Figs. S4 to S6). Briefly, COF-2 was synthesized using the same general protocol as COF-1 by condensation of Tp with p-phenylenediamine (Pa). COF-3 was synthesized by condensation of Pa and 1,3,5-benzenetricarboxaldehyde (TFB) via similar synthetic routes. Compared to COF-1, COF-2 lacks the C≡N groups in the one-dimensional (1D) channels of the framework, while COF-3 was deficient in both C=O and C≡N groups in the 1D channels (Fig. 2H and J).
C2H2 and C2H4 sorption performance
We first performed the single-component C2H2 and C2H4 sorption measurements on COF-1, COF-2, and COF-3 at 298 and 273 K to evaluate their adsorption performance (Figs. 7 to S10). The C2H2 adsorption capacities of COF-1, COF-2, and COF-3 were 110.01, 68.49, and 36.89 cm3/g at 298 K and 1 bar, respectively (Fig. 3A). The uptake capacity of COF-1 at 298 K and 1 bar is notably higher than that of other benchmark adsorbents such as NKCOF-11-ABC (68 cm3/g) [29], PAF-110 (49.95 cm3/g) [41], PAF-120 (50.85 cm3/g) [39], Na@COF-ECUT-1 (89.7 cm3/g) [38], TpPa-NO2 (63.73 cm3/g) [35], TP-ND (53 cm3/g) [36], and USTB-25-3D (57.7 cm3/g) [47]. Next, the adsorption performance of the COFs at ultralow pressures of C2H2 was investigated. The C2H2 uptake capacities (298 K) of COF-1 at ultralow pressure (0.01 bar) and low pressure (0.1 bar) were 7.97 and 38.23 cm3/g, respectively, implying a strong affinity between single-molecule traps and C2H2 (Fig. 3B and C and Table S5) [29,41,42]. To the best of our knowledge, such high uptakes at such ultralow pressure have not been reported in other COF adsorbents. Moreover, these numbers even exceed some reported state-of-the-art MOFs under similar conditions (Fig. 3D and Table S6) [15,48–56]. COF-2 and COF-3 showed much lower C2H2 adsorption capacities under similar pressures. Moreover, the uptake of C2H4 at 298 K and 1 bar for COF-1, COF-2, and COF-3 were 42.7, 35.4, and 24.5 cm3/g (Fig. 3A). The adsorption capacities of COF-1 for C2H4 at 298 K at 0.01 and 0.1 bar were 1.56 and 10.71 cm3/g, respectively, which were all much lower than the adsorption capacities for C2H2 under the same temperature and pressure conditions (Fig. 3C). Taken together, the performance of COF-1 and COF-2 shows that the introduction of C≡N groups in the 1D channels significantly improved the C2H2 adsorption capacity, while the C2H4 uptake barely changed. When both C=O and C≡N are absent (i.e., COF-3), C2H2 and C2H4 were adsorbed in almost the same amount. Clearly, the synergistic action of C=O and C≡N groups in the 1D channels of COF-1 created “single-molecule traps” with fast adsorption and high selectivity for C2H2.
Motivated by the high uptake and preferential binding of C2H2 by COF-1, the adsorption selectivity was estimated on the basis of ideal adsorbed solution theory (IAST) using a C2H2/C2H4 (1:99, v/v) gas mixture at 298 K. The predicted C2H2/C2H4 (1:99, v/v) selectivity of COF-1 was 2.6 at 298 K (Fig. 3E). COF-2 and COF-3 not possessing single-molecule traps had lower predicted IAST selectivities, particularly COF-3, which was lacking in suitable functional groups for binding C2H2. This explains why COFs devoid of suitable functional modifications have difficulty separating C2H2 and C2H4 (i.e., molecules with similar physical and chemical structures). The coverage-dependent isosteric heat of adsorption (Qst) calculated using the Clausius–Clapeyron equation was used to evaluate the affinities of each COF toward C2H2 and C2H4 (Fig. 3F and Figs. S11 to S16) [57,58]. COF-1 exhibited a Qst of 35.95 kJ/mol at near-zero loading for C2H2, while the Qst value was 25.68 kJ/mol for C2H4. The data indicate a preferred affinity toward C2H2 over C2H4 (Fig. 3F). Moreover, the Qst curve of C2H2 showed a decrease with increasing C2H2 uptake, suggesting that adsorption sites with higher interaction energy were first occupied before sites with lower energy. COF-2 showed similar Qst values for both gases and flat curves, suggesting poor adsorption selectivity. The gradually increasing Qst curves for C2H2 adsorption by COF-3 were attributed to attractive interactions between the adsorbed molecules, indicating that the molecule–framework interactions were weaker than the molecule–molecule interactions. The steeper rising curve for C2H4 showed that almost all adsorption behavior in COF-3 came from interactions between C2H4 molecules instead of the C2H4–COF interactions that we expected. The respective Qst values for the different COFs were obviously related to the functional groups in the 1D channels, with C≡N and C=O groups in COF-1 greatly enhancing the C2H2 adsorption affinity, which was also reflected in single-component adsorption isotherms and IAST results. On the basis of these results, the “single-molecule traps” in COF-1 offered well-fitting adsorption sites for C2H2, which acted to enhance the host–guest interactions between the framework and C2H2 molecules. COF-1 displayed a high C2H2 uptake and a moderate C2H2 Qst value, the latter indicating that a low energy input would be required to recover the adsorbed C2H2 (Fig. 3G and Table S8) [15,17,18,29,35,36,38,39,41,59]. These results identified COF-1 as a very promising candidate for C2H2/C2H4 separations, including the capture of trace amounts of C2H2.
C2H2/C2H4 breakthrough tests
We next carried out breakthrough experiments under dynamic conditions to examine the practical C2H2/C2H4 separation performance of COF-1. Initially, 0.45 g of COF-1 was packed into a fixed adsorbent bed, and breakthrough experiments were conducted at room temperature (298 K) using a C2H2/C2H4 (1:99, v/v) gas mixture with a flow rate of 0.5 ml/min. As shown in Fig. 3H, C2H4 first eluted through the column at 800 s/g, while C2H2 did not reach saturation until 2,000 s/g. The dynamic adsorption capacity values of COF-1 for C2H2 were calculated to be 0.26 cm3/g, allowing 3.95 cm3/g (average delivery of 0.27 ml/min/g) of high-purity C2H4 gas under 0.5 ml/min inlet C2H4-rich gas mixture (99% C2H4) at 298 K and 1 bar. These results revealed that COF-1 could efficiently bind C2H2 molecules to yield pure C2H4 under dynamic conditions. Next, further breakthrough experiments were performed using 1:1 (v/v, 1.0 ml/min) C2H2/C2H4 mixtures (Fig. S17). Under these conditions, C2H4 breakthrough occurred first at 250 s/g, followed by C2H2 at 2,430 s/g. The calculated selectivity is ~3, thus maintaining a preferential adsorption of C2H2 over C2H4. Additionally, cycling dynamic breakthrough experiments using C2H2/C2H4 (1:99, v/v) and a flow rate of 0.5 ml/min were conducted to assess the recyclability of COF-1. The breakthrough time was almost unchanged after four continuous cycles, indicating that COF-1 can be easily regenerated and recycled without any significant loss in separation performance (Fig. 3I). Simultaneously, the crystallinity of COF-1 was retained under various treatments for 24 h (Fig. S18). PXRD results further revealed that the crystallinity of COF-1 was retained after the breakthrough experiments, suggesting good stability and long-term durability (Fig. S19). The data verified the robustness of COF-1 as a selective adsorbent for C2H2.
Mechanism study
GCMC simulations, molecular dynamics (MD) simulations, and DFT calculations were performed to gain deeper insights into the mechanism of selective adsorption of C2H2 over C2H4 in COF-1. The single-component adsorption simulation by COF-1 at 298 K and 1 bar showed that C2H2 molecules were mainly adsorbed at site I (black ellipse in Fig. 4A) in the 1D channels (between the N atom of C≡N and O atom of C=O), which represented the best-fitting configuration for the single-molecule traps (Fig. 4A). Adsorption site II (green ellipse in Fig. 4A) in COF-1 contained N, O, and H atoms but showed a weaker binding affinity toward C2H2 (Fig. 4A). In contrast, the weaker density distribution for C2H4 in both site I and site II further demonstrated that COF-1 displayed a stronger adsorption affinity toward C2H2 than C2H4 when compared at the same density distribution scale (Fig. 4B). COF-2 and COF-3 showed negligible difference in C2H2 and C2H4 adsorption at the same scale (Figs. S20 and S21). It can therefore be concluded that the presence of both C≡N or C=O groups in the 1D channels of COF-1 acts synergistically to selectively capture C2H2.
Subsequently, GCMC calculations were used to predict the molecule distribution during the dynamic separation of C2H2/C2H4 (1:99, v/v) at 298 K and 1 bar (Fig. 4C). C2H2 molecules occupied the main adsorption sites in COF-1 even when the C2H2 content was only 1 vol.% (red color parts), suggesting a strong binding affinity toward C2H2. Meanwhile, the C2H4 molecules were distributed elsewhere (blue color parts). These binary gas adsorption simulations supported the idea that COF-1 showed an extraordinary C2H2 affinity compared to C2H4 at ultralow pressures, in perfect accord with the experimental results. The proper layer distance in COF-1 together with C=O, C≡N, and C–H (phenyl) groups in the 1D channels afforded effective single-molecule traps for C2H2. Radial distribution function (RDF) analysis verified a strong affinity between the target atoms in COF-1 for C2H2 molecules, evidenced by a number of g(r) peaks. As shown in Fig. 4D and E, the g(r) peak intensity of C2H2 was obviously higher than that of C2H4, further supporting the strong affinity between the single-molecule traps in COF-1 and C2H2.
DFT calculations were next conducted on different interaction models. The layer distance of COF-1 is ~3.5 Å, which was slightly larger than the molecule size of C2H2 (5.5 Å × 3.3 Å × 3.3 Å). The model shows that C2H2 was preferentially located in the single-molecule trap (site I) with a microenvironment of negative(δ−)–positive(δ+)–negative(δ−) charge distribution formed by the O atom of C=O, N atom of C≡N, and H atom of a phenyl ring. C2H2 molecules displayed positive(δ+)–negative(δ−)–positive(δ+) electronegativity and highly rotational symmetry. Specifically, O atoms and N atoms possessing a negative charge distribution (δ−) interacted with the H atom of C2H2 (δ+) from two directions, with an H atom of the phenyl ring possessing positive charge distribution (δ+) interacting with the π electrons (δ−) of C2H2 (Fig. 4F). Each C2H2 molecule is bonded by two nitrogen atoms from C≡N···H (2.96 Å), two O atoms from C=O···H (2.69 Å to 2.73 Å), and H atoms through C–H···π (2.85 Å to 2.86 Å) in site I (Fig. 4G). The molecule size of C2H4 (4.8 Å × 4.1 Å × 3.2 Å) is slightly larger than that of C2H2, which impedes adsorption in the 1D channels due to the steric effects (Fig. 4H). Moreover, the charge distribution in C2H4 is not well matched to COF-1 like it was for C2H2, leading to specific directional interactions that impede adsorption (Fig. S22). Site II in COF-1, having two N atoms and two O atoms on the same side of the adsorbing gas molecules, displayed weaker binding affinity toward both C2H2 and C2H4 (Figs. S23 and 24). Taken together, the strong host–guest interactions of COF-1 with C2H2 are in accord with experimental observations. Although site II of COF-1 was not ideal for capture of C2H2, it still favored C2H2 over C2H4 and thus helped to remove more C2H2. COF-2 and COF-3 showed little difference in their binding affinities for C2H2 and C2H4 due to the deficiency of C2H2-specific adsorption sites (Figs. S25 to 28). The calculated static binding energy of site I in COF-1 for C2H2 is −24.9 kJ/mol, compared with −6.9 kJ/mol for C2H4 at the same site (Fig. 4I). The calculated binding energies for C2H2/COF-2, C2H4/COF-2, C2H2/COF-3, and C2H4/COF-3 are −12.6, −5.3, −3.9, and −1.5 kJ/mol, respectively. These results further explain why COF-2 and COF-3 delivered inferior C2H2 adsorption capacities and poor selectivity for C2H2/C2H4 separations compared to COF-1.
Conclusion
Less
In summary, COF-1 is one of the best adsorbents developed to date for C2H4, capable of selectively adsorbing trace amounts of C2H2 under ambient conditions. The single-molecule traps in COF-1 are complementary to C2H2 in size and electrostatic potentials, allowing noncovalent interactions to trap guest C2H2 molecules. C2H4 molecules do not bind efficiently to the single-molecule traps in COF-1. Therefore, COF-1 offers a very high affinity for C2H2 at ultralow pressures, favoring the capture of C2H2 in binary C2H2/C2H4 gas mixtures. Our findings are relevant to the practical challenges of purifying C2H4 and industrial feedstocks, revealing an obvious structure–separation performance relationship along with mechanistic understanding at the molecular level. This work shows that the synergistic action of specific functional groups in the 1D channels of COFs can be harnessed to remove trace amounts of C2H2 from industrial C2H4-rich gas mixtures, thus delivering high-purity industrial C2H4 for various applications.
Materials and Methods
Less
Materials and measurements
The reagents and solvents used in this study were sourced from commercial suppliers and used without further purification. Tp, TFB, and Pa were purchased from Jilin Chinese Academy of Sciences–Yanshen Technology Co. Ltd. Db was purchased from Bide Pharmatech Co. Ltd. Mesitylene, 1,4-dioxane, and acetic acid were purchased from Shanghai Macklin Biochemical Technology Co. Ltd. Ultrapure water was obtained from a Millipore system (18.25 MΩ·cm). FT-IR spectra were collected on a SHIMADZU IRTracer-100. TGA analyses were carried out on a NETZSCH STA 2500 instrument and Rigaku TG/DTA 8122. PXRD patterns were recorded on a Cu Kα source Rigaku SmartLab SE X-ray diffractometer. SAXS data were collected on a Rigaku SmartLab SE for a zero-shift correction. SEM images were recorded on a TESCAN MIRA4 SEM. TEM and HRTEM images were recorded on a FEI Talos F200x TEM. BET surface areas were determined from N2 adsorption/desorption isotherms collected at 77 K on a Micromeritics ASAP 2020 plus. Pore size distributions were obtained from the adsorption isotherms using a Barrett–Joyner–Halenda (BJH) method. Adsorption isotherms for C2H2 and C2H4 were collected at 273 and 298 K on a Micromeritics ASAP 2020 plus. A temperature-programmed water bath was used to maintain temperatures of 273 and 298 K during the adsorption experiments. Breakthrough experiments utilized a C2H2/C2H4 (1:99, v/v) gas mixture, with gases being monitored by gas chromatography (SHIMADZU Nexis GC-2030 equipped with a thermal conductivity detector). For breakthrough experiments using a C2H2/C2H4 (50:50, v/v) gas mixture, gases were monitored using a BeiShiDe Multi-component Adsorption Breakthrough Curve Analyzer (BSD-MAB).
Syntheses
Tp (16.8 mg) and Db (16.0 mg) were dissolved in a 0.5-ml mesitylene/0.5-ml 1,4-dioxane mixed solvent solution with 0.1 ml of acetic acid (6 M) in a 5-ml glass tube. After sonication for 30 min, the mixture was frozen in a liquid nitrogen bath. Next, glass tube was flame sealed with a gas torch. Sealed tube was heated at 120 °C for 3 d, and the solid product was collected by filtration. The as-synthesized powder was washed with tetrahydrofuran and methanol. Finally, the product was dried under vacuum at 40 °C. The obtained dark red powder is denoted herein as COF-1.
Tp (16.8 mg) and Pa (13.0 mg) were dissolved in a 0.5-ml mesitylene/0.5-ml 1,4-dioxane mixed solvent solution with 0.1 ml of acetic acid (6 M) in a 5-ml glass tube. After sonication for 30 min, the mixture was frozen in a liquid nitrogen bath. Next, glass tube was flame sealed with a gas torch. Sealed tube was heated at 120 °C for 3 d, and the solid product was collected by filtration. The as-synthesized powder was washed with tetrahydrofuran and methanol. Finally, the product was dried under vacuum at 40 °C. The obtained light red powder is denoted herein as COF-2.
TFB (13.0 mg) and Pa (13.0 mg) were dissolved in a 0.67-ml mesitylene/0.33-ml 1,4-dioxane mixed solvent solution with 0.2 ml of acetic acid (6 M) in a 5-ml glass tube. After sonication for 30 min, the mixture was frozen in a liquid nitrogen bath. Next, glass tube was flame sealed with a gas torch. Sealed tube was heated at 120 °C for 3 d, and the solid product was collected by filtration. The as-synthesized powder was washed with tetrahydrofuran and methanol. Finally, the product was dried under vacuum at 40 °C. The obtained pale yellow powder is denoted herein as COF-3.
Fitting of adsorption isotherms for pure C2H2 and C2H4
Unary adsorption isotherms for C2H2 and C2H4 on COF-1, COF-2, and COF-3 were measured at 273 and 298 K, and then fitted using a dual-site Langmuir model.
q=qsat,AbAP1tA1+bAP1tA+qsat,BbBP1tB1+bBP1tB
where P is the pressure (in Pa) of the bulk gas at equilibrium with the adsorbed phase, q is the adsorbed amount per mass of adsorbent, qsat, A and qsat, B are the saturation capacities, bA and bB are the affinity coefficients, and 1/tA and 1/tB represent the deviations from the ideal homogeneous surface. The fitting parameters were displayed in Tables S8 to S10.
bA=bA0eEART,bB=bB0eEBRT
EA and EB are the energy parameters associated. bA and bB are both temperature-dependent.
Isosteric heat of adsorption
The binding energies of C2H2 and C2H4 were estimated using the isosteric heat of adsorption. Qst is defined as
Qst=RT2dlnPdT
The calculations are based on the use of the Clausius–Clapeyron equation, where 𝑃 is the pressure (in Pa), T is the temperature (in K), and R is the gas constant.
IAST calculations of adsorption selectivity
The adsorption selectivity of C2H2/C2H4 (1:99, v/v) was established using the ideal adsorption solution theory (IAST). Adsorption selectivity is defined as follows:
Sabs=xA/xByA/yB
where xA and xB are the equilibrium adsorption capacity, and yA and yB are the molar fractions of components A and B in the gas phase.
Breakthrough experiments
C2H2/C2H4 = 1:99, v/v:
In a typical experiment, 450 mg of adsorbent (in the column Ø 6 mm × 400 mm) was first activated at 353 K overnight under a He flow (10 ml/min). The column containing the adsorbent was then cooled to 298 K, whereupon a C2H2/C2H4 mixture (1:99, v/v) was introduced at a flow rate of 0.5 or 1.0 ml/min, with the gas flow rate controlled using a mass flow controller. The outlet gas from the column was continuously monitored using gas chromatography (Nexis GC-2030, SHIMADZU). To evaluate the reusability of the adsorbent, the adsorbent was regenerated in situ by heating for 12 h at 353 K under a He flow (10 ml/min), with the reusability test continued over 4 cycles.
C2H2/C2H4 = 50:50, v/v:
The adsorbent (388 mg) (in the column Ø 6 mm × 400 mm) was activated at 423 K for 120 min under a He flow (20 ml/min). The column containing the adsorbent was then cooled to 298 K, whereupon a C2H2/C2H4 gas mixture (50:50, v/v) was introduced at a flow rate of 1.0 ml/min.
Calculation of dynamic adsorption capacity
The amount of gas adsorbed i (qi) was calculated from the breakthrough curves using the following equation:
qi=CiVm×∫0t1−FF0dt
where qi is the equilibrium adsorption capacity of gas i (cm3/g); Ci is the feed gas concentration; V is the volumetric feed flow rate (ml/min); t is the adsorption time (s); F0 and F are the inlet and outlet gas molar flow rates, respectively; and m is the mass of the adsorbent (g).
DFT calculations
First-principles DFT calculations were performed with the Dmol3 module of Materials Studio [60,61]. DFT calculations were performed to provide the optimized structures and energies for the interaction of C2H2 and C2H4 with the frameworks of the COFs. Perdew–Burke–Ernzerhof (PBE) exchange-correlation functionals under the generalized gradient approximation (GGA) with the double-ξ numerical polarization (DPN) basis set were used within the Dmol3 program package in MS software [62]. Since the whole unit cell of each COF was too large, smaller primitive cells were used in the calculations. The tolerances of energy, gradient, and displacement convergence were 1.0 × 10−5 hartree, 2 × 10−3 hartree/Å, and 5 × 10−3 Å, respectively. The dispersion correction (DFT) was incorporated into calculations of the single-point energy, where the energy cutoff was 400.0 eV and the self-consistent field (SCF) tolerance was 1.0 × 10−6 eV/atom. The binding energies (ΔEbind) for the adsorbed structures consisting of a primitive cell with C2H2 and C2H4 were calculated by ΔEbind = Egas + ECOF − Ecomplex, where Ecomplex, Egas, and ECOF are the total energies of complex of gas with COFs, C2H2 and C2H4 gases, and the COFs at the optimized geometries, respectively.
GCMC simulations
GCMC simulations were carried out to model the adsorption of C2H2 and C2H4 on COF-1, COF-2, and COF-3 using the sorption module at 298 K and 101.0 kPa (fugacity). A single-unit cell was used. The simulation box was kept rigid, and periodic boundary conditions were applied in all three dimensions. Metropolis method and the COMPASS force field were used. A total of 1 × 106 equilibration steps and 1 × 107 production steps were set. The Lennard–Jones and electrostatic interactions were combined to describe gas–gas and gas–framework interactions, respectively. The cutoff of 12.5 Å was employed for Lennard–Jones interaction, and electrostatic interaction was described by Ewald summation.
MD simulations
MD simulations were performed to analyze the diffusion behavior between gases and COFs, with the simulations being carried out using the BIOVIA Materials Studio software package. The energy and geometry of the total systems of adsorbates and adsorbents obtained from GCMC calculation were optimized using the Forcite module. The universal force field (UFF) was applied for all optimizations [63]. Ewald and atom-based integration methods were applied for modeling and calculation of the electrostatic and van der Waals energy potentials at constant temperatures. In order to reach the equilibrium state, canonical ensemble (NVT) was initially applied for 500 ps on the systems. Micro-canonical ensemble (NVE) was applied on systems for 5 ps to reach equilibrium. (N, V, T, and E represent atomic number, volume, temperature, and energy, respectively.)
The RDFs g(r) representing the density distribution of characteristic atoms of adsorbate molecules around a given atom within the adsorbent framework were calculated using the following equation [64]:
gr=1ρ0nrV≈1ρ0nr4πr2δr
where ρ0 and n(r) are the number of characteristic atoms of one unit volume and of the spherical shell of radius r to r + δr, respectively. V ≈ 4πr2δr is the volume of the spherical shell of the thickness δr at a distance r from the given atom. The RDFs were obtained by the Forcite module with a cutoff of 12.5 Å and an interval δr of 0.02 Å.
Funding
Less
  • National Natural Science Foundation of China (22006036)
  • National Natural Science Foundation of China (U2167218)
  • National Natural Science Foundation of China (22341602)
  • National Natural Science Foundation of China (U2341289)
  • Robert A. Welch Foundation(B-0027)
References
Less
1.
Steiner H. Introduction to petroleum chemicals: Based on lectures given at the Manchester college of science and technology. New York: Elsevier; 2015.
2.
Wang Z, Zhang S, Chen Y, Zhang Z, Ma S. Covalent organic frameworks for separation applications. Chem Soc Rev. 2020;49(3):708–735.
3.
Farrell BL, Igenegbai VO, Linic S. A viewpoint on direct methane conversion to ethane and ethylene using oxidative coupling on solid catalysts. ACS Catal. 2016;6(7):4340–4346.
4.
Moeini N, Teimoury H, Salimi M, Bahri-Laleh N, Joshaghani M, Duran J, Poater A, Posada-Pérez S. Influence of the reaction conditions on the Ziegler-Natta catalyzed ethylene polymerization: Kinetics and properties of the resulting polymers. Polymer. 2024;293:126640.
5.
Wang Y, Peh SB, Zhao D. Alternatives to cryogenic distillation: Advanced porous materials in adsorptive light olefin/paraffin separations. Small. 2019;15(25):1900058.
6.
Chen L, Sun M, Wang Z, Yang W, Xie Z, Su B. Hierarchically structured zeolites: From design to application. Chem Rev. 2020;120(20):11194–11294.
7.
Kosinov N, Gascon J, Kapteijn F, Hensen EJM. Recent developments in zeolite membranes for gas separation. J Membr Sci. 2016;499:65–79.
8.
Hamyali H, Nosratinia F, Rashidi A, Ardjmand M. Anthracite coal-derived activated carbon as an effectiveness adsorbent for superior gas adsorption and CO2 / N2 and CO2 / CH4 selectivity: Experimental and DFT study. J Environ Chem Eng. 2022;10(9):107007.
9.
Gopalan J, Abdul Raman AA, Buthiyappan A. Green adsorbent for CO2 adsorption: MgO impregnated palm kernel shell-based activated carbon. Int J Environ Sci Technol. 2024;21(8):6773–6788.
10.
Ding L, Wei Y, Li L, Zhang T, Wang H, Xue J, Ding L, Wang S, Caro J, Gogotsi Y. Mxene molecular sieving membranes for highly efficient gas separation. Nat Commun. 2018;9(1):155.
11.
Petukhov DI, Kan AS, Chumakov AP, Konovalov OV, Valeev RG, Eliseev AA. Mxene-based gas separation membranes with sorption type selectivity. J Membr Sci. 2021;621:118994.
12.
Zhang Y, Hu J, Krishna R, Wang L, Yang L, Cui X, Duttwyler S, Xing H. Rational design of microporous MOFs with anionic boron cluster functionality and cooperative dihydrogen binding sites for highly selective capture of acetylene. Angew Chem Int Ed. 2020;59(40):17664–17669.
13.
Pei J, Shao K, Wang J, Wen H, Yang Y, Cui Y, Krishna R, Li B, Qian G. A chemically stable Hofmann-type metal-organic framework with sandwich-like binding sites for benchmark acetylene capture. Adv Mater. 2020;32(24):1908275.
14.
Gu X, Wu E, Wang J, Wen H, Chen B, Li B, Qian G. Programmed fluorine binding engineering in anion-pillared metal-organic framework for record trace acetylene capture from ethylene. Sci Adv. 2023;9(31):eadh0135.
15.
Zhang Y, Sun W, Luan B, Li J, Luo D, Jiang Y, Wang L, Chen B. Topological design of unprecedented metal-organic frameworks featuring multiple anion functionalities and hierarchical porosity for benchmark acetylene separation. Angew Chem Int Ed. 2023;62(37): Article e202309925.
16.
Dong Q, Zhang X, Liu S, Lin R, Guo Y, Ma Y, Yonezu A, Krishna R, Liu G, Duan J, et al. Tuning gate-opening of a flexible metal-organic framework for ternary gas sieving separation. Angew Chem Int Ed. 2020;59(50):22756–22762.
17.
Cui X, Chen K, Xing H, Yang Q, Krishna R, Bao Z, Wu H, Zhou W, Dong X, Han Y, et al. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene. Science. 2016;353(6295):141–144.
18.
Hu T, Wang H, Li B, Krishna R, Wu H, Zhou W, Zhao Y, Han Y, Wang X, Zhu W, et al. Microporous metal-organic framework with dual functionalities for highly efficient removal of acetylene from ethylene/acetylene mixtures. Nat Commun. 2015;6(1):7328.
19.
Zhang L, Xiao T, Zeng X, You J, He Z, Chen CX, Wang Q, Nafady A, Al-Enizi AM, Ma S. Isoreticular contraction of cage-like metal-organic frameworks with optimized pore space for enhanced C2H2/CO2 and C2H2/C2H4 separations. J Am Chem Soc. 2024;146(11):7341–7351.
20.
Bugel S, Hahnel M, Kunde T, de Sousa Amadeu N, Sun Y, Spiess A, Beglau THY, Schmidt BM, Janiak C. Synthesis and characterization of a crystalline imine-based covalent organic framework with triazine node and biphenyl linker and its fluorinated derivate for CO2/CH4 separation. Materials (Basel). 2022;15(8):2807.
21.
Chen L, Gong C, Wang X, Dai F, Huang M, Wu X, Lu CZ, Peng Y. Substoichiometric 3D covalent organic frameworks based on hexagonal linkers. J Am Chem Soc. 2021;143(27):10243–10249.
22.
Jiang H, Zhang J, Huang T, Xue J, Ren Y, Guo Z, Wang H, Yang L, Yin Y, Jiang Z, et al. Mixed-matrix membranes with covalent triazine framework fillers in polymers of intrinsic microporosity for CO2 separations. Ind Eng Chem Res. 2019;59:5296–5306.
23.
Fan H, Mundstock A, Gu J, Meng H, Caro J. An azine-linked covalent organic framework ACOF-1 membrane for highly selective CO2/CH4 separation. J Mater Chem A. 2018;6(35):16849–16853.
24.
Huang S, Hu Y, Tan L, Wan S, Yazdi S, Jin Y, Zhang W. Highly C2/C1-selective covalent organic frameworks substituted with azo groups. ACS Appl Mater Interfaces. 2020;12(46):51517–51522.
25.
Guo Z, Wu H, Chen Y, Zhu S, Jiang H, Song S, Ren Y, Wang Y, Liang X, He G, et al. Missing-linker defects in covalent organic framework membranes for efficient CO2 separation. Angew Chem Int Ed. 2022;61(41): Article e202210466.
26.
Li Z, Feng X, Zou Y, Zhang Y, Xia H, Liu X, Mu Y. A 2D azine-linked covalent organic framework for gas storage applications. Chem Commun. 2014;50(89):13825–13828.
27.
Jin F, Lin E, Wang T, Geng S, Wang T, Liu W, Xiong F, Wang Z, Chen Y, Cheng P, et al. Bottom-up synthesis of 8-connected three-dimensional covalent organic frameworks for highly efficient ethylene/ethane separation. J Am Chem Soc. 2022;144(12):5643–5652.
28.
Cao X, Zhang Z, He Y, Xue W, Huang H, Zhong C. Machine-learning-aided computational study of covalent organic frameworks for reversed C2H6/C2H4 separation. Ind Eng Chem Res. 2022;61(30):11116–11123.
29.
Wang Z, Zhang Y, Wang T, Lin E, Wang T, Chen Y, Cheng P, Zhang Z. Modulating the interlayer stacking of covalent organic frameworks for efficient acetylene separation. Small. 2023;19(32):2303684.
30.
Liu L, Hu Y, Huang S, Jin Y, Cui J, Gong W, Zhang W. A pillar[5]arene-based covalent organic framework with pre-encoded selective host-guest recognition. Chem Sci. 2021;12(3):13316–13320.
31.
Zhang P, Zou X, Song J, Tian Y, Zhu Y, Yu G, Yuan Y, Zhu G. Anion substitution in porous aromatic frameworks: Boosting molecular permeability and selectivity for membrane acetylene separation. Adv Mater. 2020;32(30): Article e1907449.
32.
Xie Y, Wang W, Zhang Z, Li J, Gui B, Sun J, Yuan D, Wang C. Fine-tuning the pore environment of ultramicroporous three-dimensional covalent organic frameworks for efficient one-step ethylene purification. Nat Commun. 2024;15:3008.
33.
Han X, Gong K, Huang X, Yang J, Feng X, Xie J, Wang B. Syntheses of covalent organic frameworks via a one-pot Suzuki coupling and Schiff's base reaction for C2H4/C3H6 separation. Angew Chem Int Ed. 2022;61(25): Article e202202912.
34.
Sun Y, Zhao G, Fu Y, Yang Y, Zhang C, An Q, Guo H. Understanding a single-Li-ion COF conductor for being dendrite free in a Li-organic battery. Research. 2022;2022(2):9798582.
35.
Xiong XH, Zhang L, Wang W, Zhu NX, Qin LZ, Huang HF, Meng LL, Xiong YY, Barboiu M, Fenske D, et al. Nitro-decorated microporous covalent organic framework (TpPa-NO2) for selective separation of C2H4 from a C2H2/C2H4/CO2 mixture and CO2 capture. ACS Appl Mater Interfaces. 2022;14(28):32105–32111.
36.
Li J, Cheng Z, Wang Z, Dong J, Jiang H, Wang W, Zou X, Zhu G. Ultramicroporous covalent organic framework nanosheets with functionality pair for membrane C2H2/C2H4 separation. Angew Chem Int Ed. 2023;62(10): Article e202216675.
37.
Suo X, Cui X, Yang L, Xu N, Huang Y, He Y, Dai S, Xing H. Synthesis of ionic ultramicroporous polymers for selective separation of acetylene from ethylene. Adv Mater. 2020;32(29):1907601.
38.
Tao Y, Krishna R, Yang L, Fan Y, Wang L, Gao Z, Xiong J, Sun L, Luo F. Enhancing C2H2/C2H4 separation by incorporating low-content sodium in covalent organic frameworks. Inorg Chem Front. 2019;6(10):2921–2926.
39.
Jiang L, Wang P, Li M, Zhang P, Li J, Liu J, Ma Y, Ren H, Zhu G. Construction of a stable crystalline polyimide porous organic framework for C2H2/C2H4 and CO2/N2 separation. Chem Eur J. 2019;25(38):9045–9051.
40.
Lu Y, He J, Chen Y, Wang H, Zhao Y, Han Y, Ding Y. Effective acetylene/ethylene separation at ambient conditions by a pigment-based covalent-triazine framework. Macromol Rapid Commun. 2018;39(2):1700468.
41.
Jiang L, Tian Y, Sun T, Zhu Y, Ren H, Zou X, Ma Y, Meihaus KR, Long J, Zhu G. A crystalline polyimide porous organic framework for selective adsorption of acetylene over ethylene. J Am Chem Soc. 2018;140(46):15724–15730.
42.
Wang Z, Zhang Y, Lin E, Geng S, Wang M, Liu J, Chen Y, Cheng P, Zhang Z. Kilogram-scale fabrication of a robust olefin-linked covalent organic framework for separating ethylene from a ternary C2 hydrocarbon mixture. J Am Chem Soc. 2023;145:21483–21490.
43.
Wang Y, Zhang X, Ba Y, Li T, Hao G, Lu A. Recent advances in carbon-based adsorbents for adsorptive separation of light hydrocarbons. Research. 2022;2022(10-11):9780864.
44.
Kandambeth S, Mallick A, Lukose B, Mane MV, Heine T, Banerjee R. Construction of crystalline 2D covalent organic frameworks with remarkable chemical (acid/base) stability via a combined reversible and irreversible route. J Am Chem Soc. 2012;134(48):19524–19527.
45.
Yang H, Hao M, Xie Y, Liu X, Liu Y, Chen Z, Wang X, Waterhouse GIN, Ma S. Tuning local charge distribution in multicomponent covalent organic frameworks for dramatically enhanced photocatalytic uranium extraction. Angew Chem Int Ed. 2023;62(30): Article e202303129.
46.
Hao M, Chen Z, Liu X, Liu X, Zhang J, Yang H, Waterhouse GIN, Wang X, Ma S. Converging cooperative functions into the nanospace of covalent organic frameworks for efficient uranium extraction from seawater. CCS Chem. 2022;4(7):2294–2307.
47.
Yu B, Geng S, Ding X, Zhou X, Jin Y, Wang H, Wang X, Zheng T, Zhang Z, Jiang J. Construction of single-crystal 3D covalent organic framework with three crossing sets of 2D sheets entanglement. Chem. 2024;10(7):2170–2179.
48.
Pal A, Chand Pal S, Cui H, Lin R, Singha D, Kumar Rana M, Chen B, Das MC. A microporous water stable MOF for consistent and selective C2H2/C2H4 separation. Sep Purif Technol. 2023;320(7600):124208.
49.
Liu Y, Xiong H, Chen J, Chen S, Zhou Z, Zeng Z, Deng S, Wang J. One-step ethylene separation from ternary C2 hydrocarbon mixture with a robust zirconium metal-organic framework. Chin J Chem Eng. 2023;59:9–15.
50.
Li Y, Wang G, Xu F, Yin Q, Zhao D, Qi J, Sui Y, Hou L, Wang Y. A robust indium-organic framework with open tubular channels for efficient separation of acetylene. Nano Res. 2023;17(4):3139–3146.
51.
Yang S, Ramirez-Cuesta AJ, Newby R, Garcia-Sakai V, Manuel P, Callear SK, Campbell SI, Tang CC, Schröder M. Supramolecular binding and separation of hydrocarbons within a functionalized porous metal-organic framework. Nat Chem. 2015;7:121–129.
52.
Zhang Y, Deng X, Li X, Liu X, Zhang P, Chen L, Yan Z, Wang J, Deng S. A stable metal-organic framework with oxygen site for efficiently trapping acetylene from acetylene-containing mixtures. Sep Purif Technol. 2023;316(3-4):123751.
53.
Xiang F, Zhang H, Yang Y, Li L, Que Z, Chen L, Yuan Z, Chen S, Yao Z, Fu J, et al. Tetranuclear CuII cluster as the ten node building unit for the construction of a metal-organic framework for efficient C2H2/CO2 separation. Angew Chem Int Ed. 2023;62(13): Article e202300638.
54.
Wang Z, Su R, Wang G, Shi W, Hou L. Methyl-functionalized Zn-MOF for selective adsorption and separation of acetylene. J Environ Chem Eng. 2023;11(5):110488.
55.
Ye Y, Xian S, Cui H, Tan K, Gong L, Liang B, Pham T, Pandey H, Krishna R, Lan P, et al. Metal-organic framework based hydrogen-bonding nanotrap for efficient acetylene storage and separation. J Am Chem Soc. 2022;144(4):1681–1689.
56.
Yang L, Yan L, Wang Y, Liu Z, He J, Fu Q, Liu D, Gu X, Dai P, Li L, et al. Adsorption site selective occupation strategy within a metal-organic framework for highly efficient sieving acetylene from carbon dioxide. Angew Chem Int Ed. 2021;60(9):4570–4574.
57.
Myers AL, Prausnitz JM. Thermodynamics of mixed-gas adsorption. AICHE J. 1965;11:121–127.
58.
Wang Z, Li Y, Wang Z, Zhou L. Factors influencing the methane adsorption capacity of coal and adsorption heat variations. Energy Fuel. 2023;37(17):13080–13092.
59.
Xiang S, Zhang Z, Zhao C, Hong K, Zhao X, Ding D, Xie M, Wu C, Das MC, Gill R, et al. Rationally tuned micropores within enantiopure metal-organic frameworks for highly selective separation of acetylene and ethylene. Nat Commun. 2011;2(11):204.
60.
Accelrys I. Materials studio. San Diego: Accelrys Software Inc; 2010.
61.
Fischer M, Hoffmann F, Fröba M. New microporous materials for acetylene storage and C2H2/CO2 separation: Insights from molecular simulations. ChemPhysChem. 2010;11(10):2220–2229.
62.
Perdew JP, Burke K, Ernzerhof M. Generalized gradient approximation made simple. Phys Rev Lett. 1996;77(18):3865.
63.
Rappé AK, Casewit CJ, Colwell K, Goddard WA III, Skiff WM. UFF, a full periodic table force field for molecular mechanics and molecular dynamics simulations. J Am Chem Soc. 1992;114(25):10024–10035.
64.
Leach AR. Molecular modelling: Principles and applications. Harlow (England): Pearson Education; 2001.
Appendix
Less
Year 2024 volume 7 Issue 8
PDF
179
104
Cite this Article
BibTeX
Article Info
doi: 10.34133/research.0458
  • Receive Date：2024-06-06
  • Online Date：2025-07-24
  • Published：2024-08-26
Article Data
Affiliations
History
  • Received：2024-06-06
  • Accepted：2024-07-29
Funding
National Natural Science Foundation of China (22006036)
National Natural Science Foundation of China (U2167218)
National Natural Science Foundation of China (22341602)
National Natural Science Foundation of China (U2341289)
Robert A. Welch Foundation(B-0027)
Affiliations
    1College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, P.R. China.
    2MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Chemical Sciences, The University of Auckland, Auckland 1142, New Zealand.
    3Department of Chemistry, University of North Texas, Denton, TX 76201, USA.

Corresponding:

* Address correspondence to: (H.Y.); (S.M.); (X.W.)
References
Share
https://castjournals.cast.org.cn/joweb/research/EN/10.34133/research.0458
Share to
QR

Scan QR to access full text

Cite this article
BibTeX
Citations
表12种不同金属材料的力学参数
科
Family		 属数
Number of
genus		 种数
Number of
species		 占总种数比例
Percentage of
total species (%)		 属
Genus		 种数
Number of
species		 占总种数比例
Percentage of total
species (%)
鹅膏菌科Amanitaceae 2 11 5.26 鹅膏菌属 Amanita 10 4.78
小菇科 Mycenaceae 2 12 5.74 丝盖伞属 Inocybe 5 2.39
多孔菌科 Polyporaceae 8 14 6.70 蜡蘑属 Laccaria 5 2.39
红菇科 Russulaceae 3 23 11.00 小皮伞属 Marasmius 6 2.87
小菇属 Mycena 11 5.26
光柄菇属 Pluteus 5 2.39
红菇属 Russula 17 8.13
栓菌属 Trametes 5 2.39
关闭全屏
  • BibTeX
  • EndNote
  • RefWorks
  • TxT
Links
Articles
Latest Articles
Most Read
Collections
Updates
Events
News
Multimedia
About
About Us
Contact
No. 86 Xueyuan South Road, Haidian District, Beijing
100081
010-62199257
qkjq@cast.org.cn

Copyright © 2025 China Association for Science and Technology. All rights reserved. For all open access content, the relevant licensing terms apply.
Sponsored by the Office of the Leading Group for Cybersecurity and Informatization of CAST, and supported by Science and Technology Review Publishing House