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1.
《Fluid Phase Equilibria》1999,165(2):157-168
A simple method is developed to estimate mixture critical temperatures (Tc), pressures (Pc), and densities (ρc) as a function of overall composition (X) from near critical region experimental coexistence data. This three-step method is applied to four mixtures, CO2–C3H8, CO2–nC4H10, C2H6–C3H8, and C3H8–nC4H10. Isothermal liquid–vapor coexistence data, which includes temperature, vapor pressure, coexisting densities (ρℓ and ρv), and coexisting compositions for the more volatile component (x1v and x1ℓ) are used. In the first step, the difference of the saturated liquid and vapor densities (ρℓ−ρv) is fitted to an empirical function in ((Pc−P)/Pc) to obtain Pc. Then P/Pc and ((ρℓ+ρv)/2ρc) are simultaneously fitted to functions of a polynomial in (X1−(x1v+x1ℓ)/2) yielding estimates of ρc and X1. Finally, the discrete estimated critical data points are fitted with an equation to provide a continuous representation of the critical lines. The method is successfully tested for the mixtures, CO2–C3H8 and CO2–nC4H10, for which there is a reasonable amount of isothermal data. The procedure is then applied to the mixtures, C2H6–C3H8 and C3H8–nC4H10, for which there are sparse data. For all four mixtures, the critical temperature line, Tc vs. X1, matches literature values within ±0.5%. The critical pressure line, Pc vs. X1, and critical density line, ρc vs. X1, match literature values, in general, within ±2%. 相似文献
2.
The title compound (C4N2H12)2Zr(C2O4)4·H2O 1 was synthesized by the reaction of ZrOCl2·8H2O, H2C2O4·2H2O and piperazinium in aqueous solution. Single-crystal X-ray analysis has revealed that compound 1 (C16H26N4O17Zr, Mr = 637.63) crystallizes in the monoclinic system, space group P21/c with a = 9.0425(3), b = 13.3844(3), c = 19.1191(5)A, β = 98.365(1)o, V = 2289.34(11) A3, Z = 4, Dc = 1.850 g/cm3, F(000) = 1304, μ = 0.577 mm-1, the final R = 0.0240 and wR = 0.0628 for 4386 observed reflections with I > 2σ(I). X-ray crystal-structure analysis suggests that compound 1 consists of [Zr(C2O4)4]4- anion and two protonated piperazinium cations. The anions are linked through hydrogen bonds of piperazinium. FT-IR and Raman spectra clearly show the existence of oxalate groups in the crystal lattice. 相似文献
3.
《Solid State Sciences》2001,3(5):623-632
Zr(PO4)2·N2C2H10 or MIL-43 and Ti2(PO4)2(HPO4)2·N2C2H10 or MIL-44 were prepared hydrothermally (20 or 4 days, 473 or 453 K, respectively, autogenous pressure) in the presence of ethylenediamine. Their structures have been determined by single-crystal X-ray diffraction. MIL-43 crystallises in the monoclinic space group P21 (No. 4) with a=11.0722(1), b=10.6631(1), c=16.4642(2) Å, β=95.991(1)° and V=1933.21(3) Å3 (final agreement factors R1(F)=0.0466, wR2(F2)=0.1096). Due to the very poor quality of the crystal, only an approached structure of MIL-44 is given; it crystallises in the triclinic space group P1 (No. 1) with a=5.0845(4), b=6.3097(5), c=12.6111(9) Å, α=77.454(1), β=78.926(2), γ=89.986(1)° and V=387.21(5) Å3. Both solids are two-dimensional and are the ion-exchanged equivalents of the layered solids αZrP and γTiP. Inorganic sheets of MIL-43 are built up from pseudo-hexagonal arrays of ZrO6 octahedra surrounded by PO4 tetrahedra pointing their terminal oxygen alternatively up and down at the interlayer space. Layers of MIL-44 are made of double (TiOP) chains built from TiO6 octahedra and PO4 tetrahedra on which HPO4 groups are grafted pointing towards the interlayer space. In both cases, diprotonated organic templates, located between the layers, interact with terminal phosphate groups and ensure via hydrogen bonds the stability of the structures. 相似文献
4.
《Radiation Physics and Chemistry》1999,53(1):37-46
The mechanism and kinetics of energy transfer from Xe(6s[3/2]1) resonance state (E=8.44 eV) to selected hydrocarbon molecules have been investigated by XeCl(B–X) (λmax=308 nm) fluorescence intensity measurements at stationary conditions in Xe–CCl4–M systems. Steady-state analysis of the fluorescence intensity dependence on the xenon and M pressure at constant CCl4 concentration shows that these process occur in the two- and three-body reactions: Xe(6s[3/2]10)+M→products, Xe(6s[3/2]10+M+Xe→products. The two- and three-body rate constants for these reactions have been found (see Table 1Table 1. Experimental parameters of Eq. (8)found by least square method in Xe–CCl4–C2H2 and Xe–CCl4–C2H4 systems for chosen xenon pressures in the range 25–150 Torr. Linear correlation coefficients (R) are also shown
P(Xe) (Torr) | C2H4 | C2H2 | ||||
---|---|---|---|---|---|---|
Empty Cell | a | b×1016 cm3/molec. | R | a | b×1016 cm3/molec. | R |
25 | 0.92 | 3.26 | 0.98 | 1.00 | 2.78 | 0.95 |
40 | 0.86 | 3.29 | 0.97 | 1.00 | 2.91 | 0.98 |
50 | 0.87 | 3.33 | 0.97 | 0.99 | 3.05 | 0.98 |
60 | 0.85 | 3.33 | 0.97 | 1.02 | 2.99 | 0.98 |
75 | 0.86 | 3.39 | 0.97 | 1.03 | 2.95 | 0.98 |
90 | 0.92 | 3.30 | 0.97 | 1.03 | 2.85 | 0.98 |
100 | 0.92 | 3.21 | 0.98 | 1.0 | 2.77 | 0.98 |
110 | 0.88 | 3.19 | 0.96 | 1.02 | 2.71 | 0.99 |
125 | 0.86 | 3.12 | 0.95 | — | — | — |
140 | 0.92 | 2.90 | 0.95 | — | — | — |
150 | 0.95 | 2.77 | 0.94 | — | — | — |