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1.
Herein, a 2-fold interpenetrated metal-organic framework (MOF) Zn-BPZ-TATB with accessible N/O active sites in nonpolar pore surfaces was reported for one-step C2H4 purification from C2H6 or C3H6 mixtures as well as recovery of C3H6 from C2H6/C3H6/C2H4 mixtures. The MOF exhibits the favorable C2H6 and C3H6 uptakes (>100 cm3 g−1 at 298 K under 100 kPa) as well as selective adsorption of C2H6 and C3H6 over C2H4. The C3H6- and C2H6-selective feature were investigated detailedly by experimental tests as well as sorption kinetic studyies. Molecular modelling revealed the multiple interactions between C3H6 or C2H6 molecules and methyl groups as well as triazine rings in pores. Zn-BPZ-TATB not only can directly generate 323.4 L kg−1 and 15.4 L kg−1 of high-purity (≥99.9 %) C2H4 from C3H6/C2H4 and C2H6/C2H4 mixtures, but also provide a large high-purity (≥99.5 %) C3H6 recovery capacity of 60.1 L kg−1 from C3H6/C2H4 mixtures. More importantly, the high-purity C3H6 (≥99.5 %) and C2H4 (≥99.9 %) with the productivities of 38.2 and 12.7 L kg−1 can be simultaneously obtained from C2H6/C3H6/C2H4 mixtures through a single adsorption/desorption cycle.  相似文献   

2.
《中国化学快报》2023,34(8):108039
Adsorptive separation of acetylene (C2H2) from carbon dioxide (CO2) 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 C2H2, but blocks off the further uptake of CO2. It thus exhibits a very high C2H2/CO2 selectivity (22.4) at ambient conditions, which is superior to most reported MOF materials. Its complete separation for 50/50 C2H2/CO2 mixtures is further evidenced by the dynamic breakthrough experiments.  相似文献   

3.
The separation of C2H2/CO2 is particularly challenging owing to their similarities in physical properties and molecular sizes. Reported here is a mixed metal–organic framework (M′MOF), [Fe(pyz)Ni(CN)4] ( FeNi-M′MOF , pyz=pyrazine), with multiple functional sites and compact one-dimensional channels of about 4.0 Å for C2H2/CO2 separation. This MOF shows not only a remarkable volumetric C2H2 uptake of 133 cm3 cm−3, but also an excellent C2H2/CO2 selectivity of 24 under ambient conditions, resulting in the second highest C2H2-capture amount of 4.54 mol L−1, thus outperforming most previous benchmark materials. The separation performance of this material is driven by π–π stacking and multiple intermolecular interactions between C2H2 molecules and the binding sites of FeNi-M′MOF . This material can be facilely synthesized at room temperature and is water stable, highlighting FeNi-M′MOF as a promising material for C2H2/CO2 separation.  相似文献   

4.
Kinetics for reactions of phenoxy radical, C6H5O, with itself and with O3 were examined at 298 K and low pressure (1 Torr) using discharge flow coupled with mass spectrometry (DF/MS). The rate constant for the phenoxy radical self‐reaction was determined to be k1 = (1.49 ± 0.53) × 10−11 cm3 molecule−1 s−1 defined by d[C6H5O]/dt=−2 k1[C6H5O]2. The rate constant for the C6H5O reaction with O3 was measured to be k2 = (2.86 ± 0.35) × 10−13 cm3 molecule−1 s−1, which may be a lower limit value. Because of much higher atmospheric abundance of ozone than that of both NO and phenoxy, the reaction of C6H5O with ozone may represent the principal fate of the phenoxy radical in the atmosphere. Products from reaction of C6H5O + C6H5O, NO, and NO2 were also investigated, and (C6H5O)2 (m/e = 186), C6H5O(NO) (m/e = 123), and C6H5O(NO2) (m/e = 139) adducts were observed as products for the reactions of C6H5O with itself, NO, and NO2, respectively. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 65–72, 1999  相似文献   

5.
Developing adsorptive separation processes based on C2H6-selective sorbents to replace energy-intensive cryogenic distillation is a promising alternative for C2H4 purification from C2H4/C2H6 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 C2H6/C2H4 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 C2H6 over C2H4 while the suitable pore spaces enforce its high C2H6 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 C2H4 product from equimolar C2H6/C2H4 mixtures at ambient conditions.  相似文献   

6.
From the mass-analysed ion kinetic energy spectra of labelled ions, kinetic energy releases and thermodynamic data, it is proved that protonated n-propylbenzene (1) isomerizes into protonated isopropyl benzene (2). It is also shown that the dissociation of the less energetic metastable ions of (2), leading to [iso-C3H7]+ and [C6H7]+ product ions, is preceded by H exchange. This H exchange involves two interconverting ion-neutral complexes [C6H6, iso-C3H7+] (2π) and [C6H7+, C3H6] (2α).  相似文献   

7.
The non-empirical generalized Kirkwood, Unsöld, and the single-Δ Unsöld methods (with double-zeta quality SCF wave-functions) are used to calculate isotropic dispersion (and induction) energy coefficients C2n, with n ? 5, for interactions involving ground state CH4, C2H6, C3H8, n-C4H10 and cyclo-C3H6. Results are also given for the related multipole polarizabilities αl, multipole sums S1/(0) and S1(?1) which are evaluated using sum rules, and the permanent multipole moments. for l = 1 (dipole) to l = 3 (octupole). Estimates of the reliability of the non-empirical methods, for the type of molecules considered, are obtained by a comparison with accurate literature values of α1S1(?1) and C6. This, and the asymptotic properties of the multipolar expansion of the dispersion energy, the use to discuss recommended representation for the isotropic long range interaction energies through R?10 where R is the intermolecular separation.  相似文献   

8.
Through integrative consideration of NICS, MO, MOC and NBO, we precisely investigated delocalization and bonding characters of C6, C6H6, B3N3 and B3N3H6 molecules. Firstly, we originally discovered and testified that C6 cluster was sp2 hybridization. Negative NICS values in 0 and 1 Å indicated that C6 had δ and Π aromaticity. Secondly, B3N3 with sp2 hybridization had obvious δ aromaticity. Finally, WBI values approved that there were delocalization in C6, C6H6 and B3N3 molecules, but B3N3H6 structure did not have delocalization with the WBI 1.0. Moreover, total WBI values of carbon, boron and nitrogen atoms were four, three and three, respectively. Namely, the electrons of B3N3H6 and B3N3 were localized in nitrogen atoms and they did not form delocalized bonding. In a word, bonding characters of carbon, boron and nitrogen atoms were dissimilar although the molecules composed of carbon, boron and nitrogen were regarded as isoelectronic structures.  相似文献   

9.
The kinetics of C6H5 reactions with C2H6 (1) and neo‐C5H12 (2) have been studied by the pulsed laser photolysis/mass spectrometric method using C6H5COCH3 as the phenyl precursor at temperatures between 565 and 1000 K. The rate constants were determined by kinetic modeling of the absolute yields of C6H6 at each temperature. Another major product, C6H5CH3, formed by the recombination of C6H5 and CH3, could also be quantitatively modeled using the known rate constant for the reaction. A weighted least‐squares analysis of the two sets of data gave k1 = 1011.32±0.05 exp[−(2236 ± 91)/T] cm3 mol−1 s−1 and k2 = 1011.37±0.03 exp[−(1925 ± 48)/T] cm3 mol−1 s−1 for the temperature range studied. The result of our sensitivity analysis clearly supports that the yields of C6H6 and C6H5CH3 depend primarily on the abstraction reactions and C6H5 + CH3, respectively. From the absolute rate constants for the two reactions we obtained the value for the H‐abstraction from a primary C‐H bond, k‐CH = 1010.40±0.06 exp(−1790 ± 102/T) cm3 mol−1 s−1. This result is utilized for analysis of other kinetic data measured for C6H5 reactions with alkanes in solution as well as in the gas phase. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 33: 64–69, 2001  相似文献   

10.
The separation of C2H2/CO2 is particularly challenging owing to their similarities in physical properties and molecular sizes. Reported here is a mixed metal–organic framework (M′MOF), [Fe(pyz)Ni(CN)4] ( FeNi‐M′MOF , pyz=pyrazine), with multiple functional sites and compact one‐dimensional channels of about 4.0 Å for C2H2/CO2 separation. This MOF shows not only a remarkable volumetric C2H2 uptake of 133 cm3 cm?3, but also an excellent C2H2/CO2 selectivity of 24 under ambient conditions, resulting in the second highest C2H2‐capture amount of 4.54 mol L?1, thus outperforming most previous benchmark materials. The separation performance of this material is driven by π–π stacking and multiple intermolecular interactions between C2H2 molecules and the binding sites of FeNi‐M′MOF . This material can be facilely synthesized at room temperature and is water stable, highlighting FeNi‐M′MOF as a promising material for C2H2/CO2 separation.  相似文献   

11.
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 m2 g−1. This COF possesses N−O paired groups which cooperatively interact with C2H2 instead of C2H4. 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 C2H2 permeability and C2H2/C2H4 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   

12.
Collisional activation spectra of [C8H8]+·, [C8H8]2+, [C6H6]+· and [C6H5]+ ions from fifteen different sources are reported. Decomposing [C8H8]+· ions of ten of these precursors isomerise to a mixture of mainly the cyclooctatetraene and, to a smaller extent, the styrene structure. Three additional structures are observed with [C8H8]+· ions from the remaining precursors. [C8H8]2+., [C8H8]+·, [C6H6]+· and [C6H5]+· ions mostly decompose from common structures although some exceptions are reported.  相似文献   

13.
Calculations of the C3H6 · LiH, C4H8 · M+, and C4H8 · MH systems and of C2H2 · MH complexes (M = Li or Na) were carried out by the unrestricted Hartree-Fock-Roothaan (UHF) method with partial optimization of the geometry using fixed geometric parameters of the C3H6 and C4H8 molecules. The standard 3-21G and 6-31G* basis sets were used. Unlike the C3H6 · LiH structure, the C4H8 · M+ and C4H8 · MH systems are typical complexes. It was found that the C4H8 · M+, C4H8 · MH, and C2H2 · MH complexes are similar in coordination of M+ ions and MH molecules by carbon atoms in spite of considerable differences in the interatomic distances (–1 A) between these atoms in the C4H8 and C2H2 molecules. The heats of formation (Q), which were calculated in the UHF/6-31G* approximation and using second- and fourth-order Möller-Plesset perturbation theory taking into account the electron correlation energy in the MP2/6-31G*. MP4(SDQ)/6-31G*, and MP4(SDTQ)/6-31G* approximations, satisfy the following relationships: Q(C2H3 · MH) < Q(C4H8 · MH) < Q(C4H8 · M+). It was observed that in going from Li to Na the corresponding values of Q tend to decrease.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 7, pp. 1636–1640, July, 1996.  相似文献   

14.
Acetylene (C2H2) removal from ethylene (C2H4) is a crucial step in the production of polymer-grade C2H4 but remains a daunting challenge because of the similar physicochemical properties of C2H2 and C2H4. Currently energy-intensive cryogenic distillation processes are used to separate the two gases industrially. A robust ultramicroporous metal–organic framework (MOF), Ni3(pzdc)2(7 Hade)2, is reported for efficient C2H2/C2H4 separation. The MOF comprises hydrogen-bonded linked one-dimensional (1D) chains, and features high-density open metal sites (2.7 nm−3) and electronegative oxygen and nitrogen sites arranged on the pore surface as cooperative binding sites. Theoretical calculations, in situ powder X-ray diffraction and Fourier-transform infrared spectroscopy revealed a synergistic adsorption mechanism. The MOF possesses S-shaped 1D pore channels that efficiently trap trace C2H2 at 0.01 bar with a high C2H2 uptake of 60.6 cm3 cm−3 and C2H2/C2H4 selectivity.  相似文献   

15.
The rate constants of the reactions of ethoxy (C2H5O), i‐propoxy (i‐C3H7O) and n‐propoxy (n‐C3H7O) radicals with O2 and NO have been measured as a function of temperature. Radicals have been generated by laser photolysis from the appropriate alkyl nitrite and have been detected by laser‐induced fluorescence. The following Arrhenius expressions have been determined: (R1) C2H5O + O2 → products k1 = (2.4 ± 0.9) × 10−14 exp(−2.7 ± 1.0 kJmol−1/RT) cm3 s−1 295K < T < 354K p = 100 Torr (R2) i‐C3H7O + O2 → products k2 = (1.6 ± 0.2) × 10−14 exp(−2.2 ± 0.2 kJmol−1/RT) cm3 s−1 288K < T < 364K p = 50–200 Torr (R3) n‐C3H7O + O2 → products k3 = (2.5 ± 0.5) × 10−14 exp(−2.0 ± 0.5 kJmol−1/RT) cm3 s−1 289K < T < 381K p = 30–100 Torr (R4) C2H5O + NO → products k4 = (2.0 ± 0.7) × 10−11 exp(0.6 ± 0.4 kJmol−1/RT) cm3 s−1 286K < T < 388K p = 30–500 Torr (R5) i‐C3H7O + NO → products k5 = (8.9 ± 0.2) × 10−12 exp(3.3 ± 0.5 kJmol−1/RT) cm3 s−1 286K < T < 389K p = 30–500 Torr (R6) n‐C3H7O + NO → products k6 = (1.2 ± 0.2) × 10−11 exp(2.9 ± 0.4 kJmol−1/RT) cm3s−1 289K < T < 380K p = 30–100 Torr All reactions have been found independent of total pressure between 30 and 500 Torr within the experimental error. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 860–866, 1999  相似文献   

16.
The chemical ionization mass spectra of five isomers of C3H6O (acetone, propionaldehyde, oxetane, propylene oxide and allyl alcohol) have been determined using a variety of reagent gases (H2, D2, N2/H2, CO2/H2 and CO/H2). The [C3H7O]+ ions produced by protonation of these isomers undergo very similar reactions to those reported for analogous [C3H7O]+ metastable ions; however, decomposing ions generated by chemical ionization appear to have somewhat higher internal energies. The results of 2H labelling studies (D2 reagent gas or labelled analogues of C3H6O) indicate that protonation occurs mainly on oxygen and are consistent with previous investigations of metastable oxonium ions. The protonated acetone ion is particularly stable, in agreement with the higher activation energies for fragmentation of this isomer than for other [C3H7O]+ structures. As the calculated heat of protonation of C3H6O is reduced by changing the reagent gas, so the extent to which fragmentation occurs decreases. This is discussed in the context of competition between fragmentation and collisional stabilization of the excited [C3H7O]+* ion. It is concluded that on average a large fraction (approaching 1) of the exothermicity of the protonation reaction resides in the [C3H7O]+* ions produced initially.  相似文献   

17.
Designing porous materials for C2H2 purification and safe storage is essential research for industrial utilization. We emphatically regulate the metal-alkyne interaction of PdII and PtII on C2H2 sorption and C2H2/CO2 separation in two isostructural NbO metal–organic frameworks (MOFs), Pd/Cu-PDA and Pt/Cu-PDA . The experimental investigations and systematic theoretical calculations reveal that PdII in Pd/Cu-PDA undergoes spontaneous chemical reaction with C2H2, leading to irreversible structural collapse and loss of C2H2/CO2 sorption and separation. Contrarily, PtII in Pt/Cu-PDA shows strong di-σ bond interaction with C2H2 to form specific π-complexation, contributing to high C2H2 capture (28.7 cm3 g−1 at 0.01 bar and 153 cm3 g−1 at 1 bar). The reusable Pt/Cu-PDA efficiently separates C2H2 from C2H2/CO2 mixtures with satisfying selectivity and C2H2 capacity (37 min g−1). This research provides valuable insight into designing high-performance MOFs for gas sorption and separation.  相似文献   

18.
Diammonium tricyanomelaminate dihydrate [NH4]2[C6N9H] · 2 H2O ( 1 ) and dimelaminium tricyanomelaminate melamine dihydrate [C3N6H7]2[C6N9H] · C3N6H6 · 2 H2O ( 2 ) were obtained by metathesis reactions from Na3[C6N9] in aqueous solution and characterized by single‐crystal X‐ray diffraction and 15N solid‐state NMR spectroscopy ( 1 ). Both salts contain mono‐protonated tricyanomelaminate (TCM) anions and crystallize as dihydrates. Considering charge balance requirements, the crystal structure of 1 (C2/c, a = 3181.8(6) pm, b = 360.01(7) pm, c = 2190.4(4) pm, β = 112.39(3)°, V = 2319.9(8) 106 · pm3) can best be described by assuming a random distribution of an ammonium ion – crystal water pair over two energetically similar sites. Apart from two melaminium cations, 2 (P21/c, a = 674.7(5) pm, b = 1123.6(5) pm, c = 3400.2(5) pm, β = 95.398(5), V = 2566(2) 106 · pm3) contains one neutral melamine per formula unit acting as an additional “solvent” molecule and yielding a donor‐acceptor type of π–stacking interaction.  相似文献   

19.
Photocatalytic water splitting to obtain hydrogen energy can transform low-density solar to high density, new and clean energy in a clean way, which is one of the ideal ways to solve the energy crisis and environmental pollution. In this paper, The CoxP/hollow porous C3N4 composite photocatalytic material was synthesized by simple methods. The photocatalytic hydrogen production rate of CoxP/hollow porous C3N4 reaches 1602 μmol g−1 h−1, which is 151 times of that of pure C3N4. The reasons for the high photocatalytic H2 evolution activity of CoxP/hollow porous C3N4 could be summarized as follows: (1) the hollow and porous structure of C3N4 shows higher light capture efficiency, larger specific surface area and more surface active sites. (2) metalloid CoxP loaded forms the Schottky contact with C3N4, which improves the photogenerated charges separation efficiency of C3N4, prolongs the photogenerated charges lifetime and improves the photocatalytic H2 evolution activity of C3N4. (3) The higher conductivity of metalloid CoxP and the lower overpotential of hydrogen production are other reasons for the higher activity of photocatalytic hydrogen production of CoxP/hollow porous C3N4. This work provides an important role for the design of efficient, stable, and efficient construction of photocatalysts for solar energy conversion.  相似文献   

20.
Adsorptive separation of C2H6 from C2H4 by adsorbents is an energy-efficient and promising method to boost the polymer grades C2H4 production. However, that C2H6 and C2H4 display very similar physical properties, making their separation extremely challenging. In this work, by regulating the pore environment in a family of chitosan-based carbon materials (C-CTS-1, C-CTS-2, C-CTS-4, and C-CTS-6)- we target ultrahigh C2H6 uptake and C2H6/C2H4 separation, which exceeds most benchmark carbon materials. Explicitly, the C2H6 uptake of C-CTS-2 (166 cm3/g at 100 kPa and 298 K) has the second-highest adsorption capacity among all the porous materials. In addition, C-CTS-2 gives C2H6/C2H4 selectivity of 1.75 toward a 1:15 mixture of C2H6/C2H4. Notably, the adsorption enthalpies for C2H6 in C-CTS-2 are low (21.3 kJ/mol), which will facilitate regeneration in mild conditions. Furthermore, C2H6/C2H4 separation performance was confirmed by binary breakthrough experiments. Under different ethane/ethylene ratios, C-CTS-X extracts a low ethane concentration from an ethane/ethylene mixture and produces high-purity C2H4 in one step. Spectroscopic measurement and diffraction analysis provide critical insight into the adsorption/separation mechanism. The nitrogen functional groups on the surface play a vital role in improving C2H6/C2H4 selectivity, and the adsorption capacities depend on the pore size and micropore volume. Moreover, these robust porous materials exhibit outstanding stability (up to 800 °C) and can be easily prepared on a large scale (kg) at a low cost (~$26 per kg), which is very significant for potential industrial applications.  相似文献   

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