首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Diffusion and solubility coefficients have been determined for the CO2?, CH4?, C2H4?, and C3H8-polyethylene systems at temperatures of 5, 20, and 35°C and at gas pressures up to 40 atm. Diffusion coefficients were obtained from rates of gas absorption in polyethylene rods under isothermal-isobaric conditions by means of a new diffusivity apparatus. The concentration dependence of the diffusion coefficients was represented satisfactorily by Fujita's free-volume model, modified for semicrystalline polymers, while the solubility of all the penetrants in polyethylene was within the limit of Henry's law. Semiempirical correlations were found for the free-volume parameters in terms of physicochemical properties of the penetrant gases and the penetrant-polymer systems. These correlations, if confirmed, should permit the prediction of diffusion and permeability coefficients of other gases and of gas mixtures in polyethylene as functions of pressure and temperature.  相似文献   

2.
Permeability coefficients have been measured for CO2, CH4, C2H4, and C3H8 in polyethylene membranes at temperatures of 5, 20, and 35°C and at applied gas pressures of up to 30 atm. The temperature and pressure dependence of the permeability coefficients was represented satisfactorily by an extension of Fujita's free-volume model of diffusion of small molecules in polymers. The results of the present steady-state permeability measurements provide further support for the conclusion reached from previous unsteady-state diffusivity measurements that Fujita's model is applicable to the transport of small molecules, such as CO2, CH4, C2H4, and C3H8, in polyethylene. It was previously thought that this model is applicable only to the transport of larger molecules, such as of organic vapors, in polymers.  相似文献   

3.
Sorption of carbon dioxide, ethylene, and nitrous oxide in poly(methyl methacrylate) (PMMA) at 35°C has been characterized for each gas as a pure component and for mixtures of carbon dioxide/ethylene and carbon dioxide/nitrous oxide. Pressures up to 20 atm were examined. Pure-component sorption isotherms are concave to the pressure axis for each of the gases. This behavior is accurately described by the dual-mode sorption model. Using only the purecomponent dual-mode parameters and the generalization of the model for gas mixtures, one can predict the total concentration of gas sorbed in the polymer to within an average deviation of ±2.01% for the CO2/C2H4/PMMA system and ±0.98% for the CO2/N2O/PMMA system. In both systems, for each component of the mixture, sorption levels were lower than corresponding pure-component sorption levels at pressures equal to the partial pressure of the respective components in the mixture. Depression of the sorbed concentration in mixture situations appears to be a general feature of the above systems and can be substantial in some situations. For the CO2/C2H4/PMMA system, use of pure-component sorption data to estimate the total sorbed concentration in the mixture would be in error by as much as 40% if one failed to account for competition phenomena responsible for depression in mixed-gas situations. Mixture pressures as high as 20 atm were studied for both systems and in the CO2/N2O/PMMA system sorbed concentrations reach 33.90 [cm3(STP)/cm3 polymer] without any significant deviation from model predictions.  相似文献   

4.
The complex η55-(CO)3Mn(C5H4-C5H4)(CO)2Fe-η15-C5H4Mn(CO)3 was synthesized by the reaction of η5-Cp(CO)2Fe-η15-C5H4Mn(CO)3 with BunLi (THF, ?78 °C) and then with anhydrous CuCl2. The complex μ-(C≡C)[C5H4(CO)2Fe-η15-C5H4Mn(CO)3]2 was prepared by the reaction of η5-IC5H4(CO)2Fe-η15-C5H4Mn(CO)3 with Me3SnC≡CSnMe3 (2:1) in the presence of Pd(MeCN)2Cl2.  相似文献   

5.
The reactons of (CO2)2+ and (CO)2+ with various additives have been investigated using the NBS high-pressure photoionization mass spectrometer at total pressures of 0.4–1.0 torr of either CO2 or CO. The additives include CH4, CD4, C2H2, O2, H2O, 15,14N2O, and CO in both CO2 and 13CO2. Second- and third-order rate coefficients based on an ambipolar diffusion model are reported for 25 separate reaction pairs at 295°K, as well as sequential cationic reaction mechanisms. An approximate value of 225 ± 3 kcal/mol (941 ± 13 kJ/mol) was derived for ΔHf (CO)2+ based on the kinetics observed in various CO-additive mixtures. Some projections regarding the utility of the data under other conditions are also included.  相似文献   

6.
The reaction of Cp2MCl2 complexes (M=Ti and Zr) with 2 equiv. of (OC)3Mn(η15-C5H4)Fe(CO)25-C5H4COONa) results in the formation of the pentanuclear complexes (OC)3Mn(η15-C5H4)Fe(CO)25-C5H4CO2)]2M(η5-C5H5)2, which are characterized by IR and1H NMR spectroscopy and cyclic voltammetry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1055–1058, May, 1997.  相似文献   

7.
The molar excess enthalpies measured for binary mixtures of 2-, 3-, 4-picoline +n-alkane (C6H14-C10H22) at 298.15 K have been compared with the Prigogine-Flory-Patterson theory and the Extended Real Associated Solution model estimations.
Zusammenfassung Die bei 298.15 K gemessenen molaren Zusatzenthalpien binärer Mischungen aus 2-,3-,4-Picolin und einemn-Alkan (C6H14-C10H22) wurden mit den nach der Prigonine-Flory-Patterson-Theorie und den nach dem erweiterten Modell real assoziierter Lösungen (ERAS) berechneten Weiten verglichen.
  相似文献   

8.
Permeability coefficients for Ar, SF6, CF4, and C2H2F2 (1,1-difluoroethylene) in polyethylene membranes were determined from steady-state permeation rates at temperatures from 5 to 50°C, and at applied gas pressures of up to 15 atm. The temperature and pressure dependence of the permeability coefficients was represented satisfactorily by an extension of Fujita's free volume model of diffusion of small molecules in polymers. The parameters required by this model were determined from independent absorption (diffusivity) measurements with the above gases in polyethylene rods. The present work confirms the results of previous studies with CO2, CH4 C2H4 and C3H8 in polyethylene.  相似文献   

9.
Reactions of the Cycloheptatrienyl Complexes [η7-C7H7W(CO)3]BF4 and η7-C7H7Mo(CO)2Br with Neutral Ligands and the Electrochemical Reduction of the Wolfram Complex Compounds of the type [η7-C7H7M(CO)2L][BF4] (L = P(C6H5)3, As(C6H5)3, Sb(C6H5)3 for M = W and L = N2H4 for M = Mo) were synthesized and characterisized. The iodide η7-C7H7W(CO)2I reacts with the diphosphine ((C6H5)2PCH2)2 to give the trihapto complex η3-C7H7 W(CO)2I((C6H5)2PCH2)2. In the case of η7-C7H7Mo(CO)2 Br reaction with hydrazine leads to the substitution product [η7-C7H7 Mo(CO)2N2H4], which can be stabilized by large anions. The binuclear complex [C7H7W(CO)3]2 has been synthesized electrochemically.  相似文献   

10.
Rate constants for the reactions of atomic oxygen (O3P) with C2H3F, C2H3Cl, C2H3Br, 1,1-C2H2F2, and 1,2-C2H2F2 have been measured at 307°K using a discharge-flow system coupled to a mass spectrometer. The rate constants for these reactions are (in units of 1011 cm3 mole?1 s?1) 2.63 ± 0.38, 5.22 ± 0.24, 4.90 ± 0.34, 2.19 ± 0.18, and 2.70 ± 0.34, respectively. For some of these reactions, the product carbonyl halides were identified.  相似文献   

11.
A highly water and thermally stable metal-organic framework (MOF) Zn2(Pydc)(Ata)2 (1, H2Pydc = 3,5-pyridinedicarboxylic acid; HAta = 3-amino-1,2,4-triazole) was synthesized on a large scale using inexpensive commercially available ligands for efficient separation of C2H2 from CH4 and CO2. Compound 1 could take up 47.2 mL/g of C2H2 under ambient conditions but only 33.0 mL/g of CO2 and 19.1 mL/g of CH4. The calculated ideal absorbed solution theory (IAST) selectivities for equimolar C2H2/CO2 and C2H2/CH4 were 5.1 and 21.5, respectively, comparable to those many popular MOFs. The Qst values for C2H2, CO2, and CH4 at a near-zero loading in 1 were 43.1, 32.1, and 22.5 kJ mol−1, respectively. The practical separation performance for C2H2/CO2 mixtures was further confirmed by column breakthrough experiments.  相似文献   

12.
Heterobimetallic Phosphanido-bridged Dinuclear Complexes - Syntheses of cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6-iPr3C6H2)}2M(CO)4] (R?Me, M?Cr, Mo; R?H, M?Mo) The zirconocene bisphosphanido complexes [(η-C5H4R)2Zr{PH(2,4,6-iPr3C6H2)}2] (R?Me, H) react with [(NBD)M(CO)4] (NBD?norbornadiene, M?Cr, Mo) to give only one diastereomer of the phosphanido-bridged heterobimetallic dinuclear complexes cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6-iPr3C6H2)}2M(CO)4] [R?Me, M?Cr ( 1 ), Mo ( 2 ); R?H, M?Mo ( 3 )]. However, no reaction was observed between [(η-C5H5)2Zr{PH(2,4,6-tBu3 C6H2)}2] and [Pt(PPh3)4]. 1—3 were characterised spectroscopically. For 1—3 , the presence of the racemic isomer was shown by NMR spectroscopy. No reaction was observed at room temperature for 3 and CS2, (NO)BF4, Me3NO or PH(2,4,6-Me3C6H2)2. With Et2AlH or PhC?CH decomposition of 3 was observed.  相似文献   

13.
Triorganoantimony and Triorganobismuth Derivatives of 2-Pyridinecarboxylic Acid and 2-Pyridylacetic Acid. Crystal and Molecular Structures of (C6H5)3Sb(O2C-2-C5H4N)2 and (CH3)3Sb(O2CCH2-2-C5H4N)2 Triorganoantimony and triorganobismuth dicarboxylates R3M(O2C-2-C5H4N)2 (M = Sb, R = CH3, C6H5, 4-CH3OC6H4; M = Bi, R = C6H5, 4-CH3C6H4) and (CH3)3Sb(O2CCH2-2-C5H4N)2 have been prepared from (CH3)3Sb(OH)2, R3SbO (R = C6H5, 4-CH3OC6H4), or R3BiCO3 (R = C6H5, 4-CH3C6H4) and the appropriate heterocyclic carboxylic acid. Vibrational spectroscopic data indicate a trigonal bipyramidal environment of M the O(? C)-atoms of the carboxylate ligands being in the apical and three C atoms (of R) in the equatorial positions; in addition coordinative interaction occurs in the 2-pyridinecarboxylates between M and O(?C) of one and N of the other carboxylate ligand and in (CH3)3)Sb(O2CCH2-2-C5H4N)2 between Sb and O(?C) of both carboxylate ligands. (C6H5)3Sb(O2C-2-C5H4N)2/(CH3)3Sb(O2CCH2-2-C5H4N)2 crystallize monoclinic [space group P21/c/P21/n; a = 892.6(9)/1043.4(6), b = 1326.9(6)/3166.2(18), c = 2233.1(9)/1147.5(7) pm, β = 99.74(8)°/97.67(5)° Z = 4/8; d(calc.) = 1.522/1.553 × Mg m?3; Vcell = 2606.7 × 106/3757.0 × 106pm3, structure determination from 3798/4965 independent reflexions (F ≥ 4.0 σ(F))/(I ≥ 1.96 σ(I), R(unweighted) = 0.024/0.036]. Sb is bonding to three C6H5/CH3 groups in the equatorial plane [mean distances Sb? C: 212.2(3)/208.7(6) pm] and two carboxylate ligands via O in the apical positions [Sb? O distances: 218.5(2), 209.9(2)/212.1(3), 213.2(3) pm]. In (C6H5)3Sb(O2C-2-C5H4N)2 there is a short Sb? O(?C) and a short Sb? N contact [Sb? O: 272.1(2), Sb? N: 260.2(2) pm] and distoritions of the equatorial angles [C? Sb? C: 99.2(1)°, 158.2(1)°, 102.0(1).] and of the axial angle [O? Sb? O: 169.9(1)°], and in (CH3)3Sb(O2CCH2-2-C5H4N)2, which contains two different molecules in the asym-metric unit, there are two Sb? O(?C) contacts [Sb? O, mean: 302.2(4), and 310.7(4)pm, respectively] and distortions of the equatorial angles [C? Sb? C: 114.5(2)°, 132.4(3)° 113.1(2)°, and 123.9(3)° 115.5(2)°, 120.6(3)°, respectively] and of the axial angles [O? Sb? O: 174,9(1)°, 177.9(1)°, respectively].  相似文献   

14.
A series of arylantimony ferrocenecarboxylates with the formula (C5H5FeC5H4CO2)nSbAr(5?n) (n = 1, 2; Ar = C6H5, 4‐CH3C6H4, 3‐CH3C6H4, 2‐CH3C6H4, 4‐ClC6H4, 4‐FC6H4) were synthesized and characterized by elemental analysis, IR, 1H NMR and mass spectra. The crystal structures of (C5H5FeC5H4CO2)2Sb(4‐CH3C6H4)3 and C5H5FeC5H4CO2SbPh4 were determined by X‐ray diffraction. Four human neoplastic cell lines (HL‐60, Bel‐7402, KB and Hela) were used to screen these compounds. The results indicate that these compounds at 10 µM show certain in vitro antitumor activities. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

15.
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   

16.
《Fluid Phase Equilibria》1999,163(2):165-173
Monte Carlo simulation has been applied to calculate the pVT relationship of CO2+butane (n-C4H10 and i-C4H10) systems at 310.93 K and up to 9.5 MPa. CO2 is treated as a single-site molecule and butanes are treated as four-site molecules. The Lennard–Jones (12–6) potential is used as the site–site potentials and the combining rules proposed by Jorgensen et al. [W.L. Jorgensen, J.D. Madura, C.J. Swenson, J. Am. Chem. Soc. 106 (1984) 6638.] are adopted for unlike site pairs. The calculated results of the pVT relationship show good agreement with the experimental data [T. Tsuji, S. Honda, T. Hiaki, M. Hongo, J. Supercrit. Fluids 13 (1998) 15.] by introducing an intersite interaction parameter between unlike molecules. Furthermore, the radial distribution functions and the number of CO2 and butanes around butanes are calculated as a fundamental information on the microscopic structures. It is found that the radial distribution functions and the number of CO2 and n-C4H10 around n-C4H10 are different from those of CO2 and i-C4H10 around i-C4H10.  相似文献   

17.
Zusammenfassung Die vorliegende Arbeit beschreibt ein neues Verfahren zur gas-chromatographischen Simultananalyse von N2, O2, CO, CO2, N2O, SO2, CH4, C2H4 und C2H6 im Konzentrations-bereich von 10% bis 10 ppm ohne Voranreicherung. Die temperaturprogrammierte Trennung der Einzelkomponenten erfolgt nach Vorsäulensplitting auf zwei parallel geschalteten Säulen. Zur Emittlung der Retentionszeiten und der Peakflächen werden zwei voneinander unabhängige Ultraschalldetektoren verwendet, deren Analogsignale nach Digitalisierung in einem Mikrocomputer verarbeitet werden. Instrumentierung und chromatographische Einzelheiten werden beschrieben und diskutiert.
Simultaneous gas chromatographic determination of N2, O2, CO, CO2, N2O, SO2, CH4, C2H4 and C2H6 at the ppm-level. Part I
Summary A new procedure for the simultaneous determination of N2, O2, CO, CO2, N2O, SO2, CH4, C2H4 and C2H6 by gas chromatography is described. Concentrations from 10% down to 10 ppm can be determined without preconcentration. After a pre-column splitting the individual compounds of the sample are separated by a uniform temperature program on two different columns in parallel. Detection of the effluents is achieved by two individual ultrasonic detectors, the data from which are processed in a micro-computer. Instrumentation and gas chromatographic details are described and discussed.
  相似文献   

18.
Steady-state permeation rates for pure CO2 and CH4 and their binary mixtures through homogeneous dense cellulose triacetate membranes have been measured at three temperatures between 20 and 40°C and pressures up to 2.8 MPa. The pressure dependence of the mean permeability coefficient for CO2 can be described by the total immobilization model in conjunction with a modified free-volume model. No appreciable pressure dependence of the permeability coefficient for CH4 is observed, while the permeability coefficients for CH4 in binary mixture of CO2 and CH4 depend on applied gas pressure. The pressure dependences of the mean permeability coefficients for the components in the binary mixture are discussed in terms of the above mobility model. Membrane plasticization induced by CO2 affects permeation by both gases.  相似文献   

19.
A reinvestigation of the reaction between C2(CO2Me)2 and RuH(PPh3)2(η-C5H5) and some related complexes is reported. Initial cis addition is followed by conversion into the trans isomer. In the case of the bis-(PPh3) complex, isomerisation is followed by chelation of the ester CO group with concomitant displacement of one PPh3ligand. The resulting chelate complex reacts with CO or CNBut to give the (Z)-RuC(CO2Me)CH(CO2Me) complexes; the (E)-isomer of the carbonyl complex is obtained by addition of C2(CO2Me)2to RuH(CO)(PPh3)(η-C5H5). The 1Hand 13C NMR spectra are not a reliable guide to assignment of the stereochemistry of the vinyl group. Other products isolated from the initial reaction are the bis-insertion product Ru{C(CO2Me)C(CO2Me)C(CO2Me)CH(CO2Me)} -(PPh3)(η-C5H5) and the 1/2 PPh3/C2(CO2Me)2 adduct. The molecular structures of Ru{(Z)-C(CO2Me)CH(CO2Me)}(CO)(PPh3(η-C5H5) · 0.5EtOH, Ru{(E)-C(C2Me)CH(CO2Me)}(dppe)(η-C5H5) and Ru{C(CO2Me)C(CO2Me)C(CO2-Me)CH(CO2Me)}(PPh3)(η-C5H5) have been determined. The cis isomer is monoclinic, space group P21,with a 9.328(8), b 17.385(10), c 10.356(7) Å, β 101.78(3)° and Z = 2; 2107 data with I ≥ 2.5σ(I) were refined to R = 0.076 Rw = 0.085. The trans isomer is triclinic, space group P1, with a 10.404(7) b 11.221(6), c 13.230(9) Å, α 92.67(5), β 110.56(5), γ 106.21(5)° and Z = 2; 2520 data with I ≥ 2.5σ(I) were refined to R = 0.055 Rw = 0.068. The butadienyl complex is monoclinic, space group P21/a, with a 19.655(8), b 8.674(4), c 21.060(5) Å, β 116.22(3)° and Z = 4; 2724 data with I ≥ 2.5σ(I) were refined to R = 0.042, Rw = 0.047.  相似文献   

20.
The reaction of O(3P) with 1-C4H8 was examined in the presence of CO which scavenges HO radicals to produce CO2. From the CO2 quantum yield, an upper limit to the efficiency of HO production in the reaction of O(3P) with 1-C4H8 was found to be 0.02 at both 298° and 473°K.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号