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1.
The sound velocities of aqueous NaCl, Na2SO4, MgCl2, and MgSO4 solutions were measured from 25 to 95°C in 10o intervals from dilute to saturated solutions. The results were combined with our earlier data and fitted to functions of molality and temperature to within ±0.4 m-sec–1. The adiabatic compressibilities S were calculated from sound speeds and used to calculate the adiabatic apparent molal compressibilities . Isothermal compressibilities and isothermal apparent molal compressibilities were calculated from S using literature values for the expansibilities and heat capacities. The values of were extrapolated to infinite dilution using the Debye-Huckel limiting law to determine partial molal compressibilities. The apparent molal compressibilities were fitted to Pitzer's equations. The Pitzer parameters for the concentration dependence of were determined as a function of temperature. Correlations of and V at various temperatures were found for the electrolytes.  相似文献   

2.
Triterpene glycosides from Pulsatilla chinensis   总被引:1,自引:0,他引:1  
Four triterpene glycosides were isolated from the roots of Pulsatilla chinensis (Bunge) Regel (Ranunculaceae). Two new glycosides, chinensiosides A (1a) and B (2), were identified as 3-O-[-L-rhamnopyranosyl-(12)--L-arabinopyranosyl]-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid and 3-O-{-L-rhamnopyranosyl-(12)-[-D-glucopyranosyl-(14)]--L-arabinopyranosyl}-28-O-[-L-rhamnopyranosyl-(14)--D-glucopyranosyl-(16)--D-glucopyranosyl]-3,23-dihydroxylup-20(29)-en-28-oic acid. The other two glycosides were identified as previously known hederasaponin C (3) from Hedera helix and glycoside III (4) from Pulsatilla cernua.  相似文献   

3.
Molecular isotope exchange of CO with14CO for Rh6(CO)16/Sn(II)–SiO2, Rh6(CO)16/Al2O3, Rh(I)(CO)2/Al2O3, Rh4(CO)12/Al2O3 carbonyl complexes of rhodium has been studied. Estimates of the activation energies and a mechanism of the CO exchange are suggested.
, (Rh6(CO)16/Sn(II)–SiO2, Rh6(CO)16/Al2O3, RhI(CO)2/Al2O3, Rh4(CO)12/Al2O3), 14CO. CO .
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4.
Ru and Cu samples supported on SiO2, Al2O3 and MgO were studied by the temperature-programmed reduction (TPR) technique. Experiments were carried out both on unreduced impregnated salts and after oxidation of already reduced samples.The TPR profiles were found to be strongly dependent on the support used, indicating different degrees of interaction between the metal and the support, which can be ranked as MgOAl2O3>SiO2. It is suggested that the interaction occurs through the formation of surface complexes difficult to reduce. The decrease in hydrogen consumption observed on the Ru samples with the number of TPR cycles is attributed to the difficulty in oxidizing large Ru particles.
Zusammenfassung Auf SiO2, Al2O3 und MgO aufgebrachte Ru- und Cu-Proben wurden mittels temperaturprogrammierter Reduktion (TPR) untersucht. Experimente wurden sowohl an unreduzierten Salzimprägnierungen als auch nach Oxydation von bereits reduzierten Proben ausgeführt. Die TPR-Profile sind stark vom benutzten Trägen abhängig, was auf unterschiedliche Grade der Wechselwirkung zwischen Metall und Träger hindeutet; die Reihenfolge ist MgOAl2O3>SiO2. Es wird vermutet, daß das Wesen der Wechselwirkung in der Bildung von schwer reduzierbaren Oberflächenkomplexen zu suchen ist. Die bei Ru-Proben mit der Zahl der TPR-Zyklen beobachtete Verminderung des Wasserstoffverbrauchs wird mit der Schwierigkeit, große Ru-Partikel zu oxydieren, in Zusammenhang gebracht.

- () SiO2, l23 MgO. , , , . , , MgO Al2O3>SiO2. , , . , .
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5.
Tetrametal clusters such as Ru4(CO)13(-PPh2)2 and Ru4(CO)10(-PPh2)4 are 64-electron systems and, with five metal-metal interactions, are formally electron rich. In fact these clusters have unusual rhomboidal (or flat butterfly) structures with three or four elongated Ru-Ru bonds. With molecular orbitals antibonding with respect to metal metal interactions occupied in such clusters, facile two electron oxidation or ligand dissociation processes should occur, giving electron precise molecules. The molecule Ru4(CO)13(-PPh2)2 1a undergoes a remarkable, reversible transformation upon loss of CO affording (-H)Ru4(CO)10(-PPh2)[4-1(P),1(P),1(P),1,2-{C6H4}PPh]3 a cluster which contains a five coordinate phosphido bridge and an orthometallated 2 arene ring. This conversion is reversible under CO. These and other results which will be discussed confirm that M4 clusters with electrons in excess of the expected EAN rule count may exhibit unusual reactivity. The solid-state CP/MAS and static powder31P NMR spectra of some of these clusters exhibit99/101Ru-31P couplings, values of which have been measured for the first time.  相似文献   

6.
Summary Crystals of Co2(X 2O7)·2H2O,X=P/As were synthesized under hydrothermal conditions. Their crystal structures were determined by single crystal X-ray diffraction:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2)Å, =94.77(2)/94.74(2)°, space group P21/n,R=0.032/0.046,R w=0.028/0.034 for 2423/2042 reflections and 131/119 variables. Within the twoXO4 tetrahedra connected via a common corner to anX 2O7 group the average P-O bond lengths are approximately equal (1.540 and 1.543 Å), but As-O differs significantly (1.685 and 1.696 Å). A comparison with the isotypic Mn and Mg pyrophosphates shows a correlation between the ratio Me-O/X-O and the angle O-X-O.
Vergleich der Kristallstrukturen von Co2(X 2O7)·2H2O,X=P und As
Zusammenfassung Kristalle von Co2(X 2O7)·2H2O,X=P/As wurden unter Hydrothermalbedingungen synthetisiert. Ihre Kristallstrukturen wurden mittels Röntgenbeugung an Einkristallen bestimmt:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2) Å, =94.77(2)/97.74(2)°, Raumgruppe P21/n,R=0.032/0.046,R w=0.028/0.034 für 2423/2042 Reflexe und 131/119 Variable. In den beiden über eine gemeinsame Ecke zuX 2O7-Gruppen verknüpftenXO4-Tetraedern sind die mittleren P-O-Abstände ungefähr gleich (1.540 und 1.543 Å), hingegen differiert As-O signifikant (1.685 und 1.696 Å). Ein Vergleich mit den isotypen Mn- und Mg-Pyrophosphaten zeigt eine Korrelation zwischen dem Quotienten Me-O/X-O und dem WinkelX-O-X.
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7.
Seven complex compounds exhibiting the compositions Ni(en)3Ni(CN)4·H2O (I), Ni(en)3Ni(CN)4 (II),-Ni(en)2Ni(CN)4 (III), Ni(en)Ni(CN)4·2H2O (IV), Ni(en)Ni(CN)4 (V), Ni(en)2Ni(CN)4 · 2.5H2O (VI) and-Ni(en)2Ni(CN)4 (VII) were prepared from the system Ni-en-[Ni(CN)4]2–-H2O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.
Zusammenfassung Aus einem System Ni-en-[Ni(CN)4]2–-H2O wurden sieben Komplexe der Formeln Ni(en)3Ni(CN)4·H2O (I), Ni(en)3Ni(CN)4 (II),-Ni(en)2Ni(CN)4 (III), Ni(en)Ni(CN)4·2H2O (IV), Ni(en)Ni(CN)4 (V), Ni(en)2Ni(CN)4 · 2.5H2O (VI) und-Ni(en)2Ni(CN)4 (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.

Ni- -[No(N)]2 -2 Ni(en)3Ni(CN)4 · 2 (I), Ni(en)3Ni(CN)4 (II),-Ni(en)2Ni(CN)4 (III), Ni(en)Ni(CN)4-2H2O (IV), Ni(en)Ni(CN)4 (V), Ni(en)2Ni(CN)4 · 2,5H2O (VI) -Ni(en)2Ni(CN)4 (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .
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8.
The structural characterizations of some copper(I) halide (CuX) adducts with norbornadiene (nbd) are recorded. CuCl : nbd (1:1)4 (a redetermination), (2:1)2(|), are systems both based around Cu4Cl4 cubane-type cluster arrays. CuBr : nbd (7:3)(|)( 0.5 MeOH), a complex polymer with 3-symmetry, is believed to be the complex previously described as an adduct of 2:1 stoichiometry. Attempts to obtain an iodide counterpart have resulted in the definition of an ephemeral adduct CuI : MeCN (3:2)(|). 0.5 C7H8 in which, remarkably, the nbd is uncoordinated; the complex is a polymer, related to the [AgX(quinoline)](|) (X = Cl, Br) saddle polymer.  相似文献   

9.
For an electric model, relationships have been established as a function of the DTA baseline shift, the intensity of the signal, the slope of the leading edge, the heating rate, the thermal resistance of the heating disc built into the DTA apparatus, the contact resistance between the disc and the sample holders, and the heat resistance between the two measuring sites. Some of the relationships obtained supported knowledge acquired earlier by other approaches, and some furnished new information. The limits of use of this simple model are indicated.
Zusammenfassung Unter Anwendung eines elektrischen Modells wurden Zusammenhänge als Funktion der Verschiebung der Basislinie der DTA, der Signalintensität, der Steile der Leitkante, der Aufheizgeschwindigkeit, des Wärmewiderstandes der in das DTA-Gerät eingebauten Heizscheibe, des Kontaktwiderstandes, zwischen Scheibe und Probenbehälter und des Wärmewiderstandes zwischen den beiden Meßstellen ermittelt. Ein Teil der erhaltenen Zusammenhänge bestätigte von anderen Annäherungen her bereits vorliegende Kenntnisse, ein anderer Teil lieferte neue Informationen. Auf die Grenzen und der Nutzen dieses einfachen Modells wurden hingewiesen.

Résumé A l'aide d'un modèle électrique, on a établi des relations décrivant l'influence de la dérive de la ligne de base ATD, de l'intensité du signal, de la pente du bord du pic, de la vitesse de chauffage, de la résistance thermique du disque de chauffage incorporé dans l'appareil ATD, de la résistance de contact entre le disque et les porte-échantillons et enfin, de la résistance thermique entre les deux points de mesure. Une partie des relations obtenues confirme les connaissances déjà acquises par d'autres approches, l'autre partie fournit des renseignements nouveaux. Les limites d'utilisation de ce modèle simple sont indiquées.

, , , , , , , . , — . .
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10.
A novel nano-TiO2 polymer modified glassy carbon (GC) electrode was developed for the determination of an organophosphorous pesticide, fenitrothion (-NO2), in citrate buffer solution. The electrochemical behavior of fenitrothion was characterized by using cyclic voltammetry. An irreversible form, -NO2, was transformed into a reversible redox couple (-NHOH/-NO), and it can be used to determine trace fenitrothion by square wave voltammetry. The experimental parameters, such as film thickness, pH value, accumulation potential and time were optimized. Interestingly, a cyclic voltammetric scan was observed to be more effective than a constant potential for the accumulation of fenitrothion. A linear response over a fenitrothion concentration of 2.5×10–8 to 1.0×10–5M was exhibited, with a detection limit of 1.0×10–8M (S/N=3). The high sensitivity and selectivity of this film electrode was demonstrated by its practical application to the determination of trace amounts of fenitrothion in lake water and apple samples.  相似文献   

11.
Interaction of NO with NiCr2O4 has been studied at 473–1173 K. It has been established that on nickel-chromium spinels NO decomposition practically does not take place. Nitric oxide can interact only with prereduced samples to reoxidize them.
473–1173 NO NiCr2O4. , NO . (II) ; .
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12.
Sol-gel routes in the ternary system Al2O3-TiO5-ZrO2 were investigated to prepare Al2TiO5-ZrO2 mixed powders. The preparation of ZrTiO4 and Al2TiO5 was studied before going on with the ternary system. Zirconium titanate precursor gels were prepared from Ti(OPri)4 and Zr(OPrn)4 mixtures. The crystallization of ZrTiO4 develops at T<700°C. Al2TiO5 was prepared by different ways, using mixtures of Al(OBus)2(C6H9O3) with Ti(OPr i )4 (i), or with acetic acid addition (ii). Route (i) leads to a separate crystallization of TiO2 and -Al2O3, with subsequent formation of -Al2TiO5 at T1360°C. Although the pseudobrookite -Al2TiO5 is thermodynamically unstable below 1280°C, route (ii) leads to the crystallization of metastable -Al2TiO5 at T800°C. At increasing temperature, -Al2TiO5 decomposes into TiO2 and -Al2O3, then the two compounds react to form stable -Al2TiO5. For the ternary system, all the preparation routes which were studied lead to ZrTiO4 and -Al2O3 with subsequent reaction (at T1500°C) to give -Al2TiO5 and ZrO2.  相似文献   

13.
The effects of feed composition on the adsorption dynamics and the optimal process design were studied from the experimental and simulated results in the H2 layered bed PSA with activated carbon and zeolite 5A. The breakthrough results using the base composition (56.4 vol% H2; 26.6 vol% CH4; 8.4 vol% CO; 5.5 vol% N2; and 3.1 vol% CO2) in various layered beds were compared with those using the higher nitrogen composition and the no nitrogen composition. In the breakthrough dynamics, the propagation velocity of wave front of each component was closely related to the slope of isotherm estimated at its concentration in the feed. Breakthrough behavior at each layered bed in the higher nitrogen composition showed similar trends as that in the base composition. However, the no nitrogen composition showed different breakthrough behavior from the other groups. In this feed composition, it was observed that the order of CO and CH4 breakthrough times was reversed with a change in the carbon-to-zeolite ratio. Based on the adsorption dynamics and breakthrough behavior of each feed composition group in various layered beds, the effect of feed composition on a seven-step two-bed PSA process for the H2 recovery from coke oven gas was investigated numerically to develop a well-designed H2 PSA process under various operating conditions. As expected from the breakthrough results, the trends of the PSA performance in the higher nitrogen composition were similar to those in the base composition except for the slight decrease in the optimal carbon-to-zeolite ratio. However, in case of the no nitrogen composition, high purity product was obtained from the activated carbon-rich layered bed PSA because the adsorption capacity of the activated carbon for impurities was superior to that of zeolite. As a result, the optimum carbon-to-zeolite ratio at each operating condition was slightly changed depending on the propagation velocity of each component on each layer.  相似文献   

14.
The catalysts prepared sequentiallyvia the interaction of C3H5PdC5H5 with the surface of evacuated Pr4O7/C and reduction with H2 at 573 K, contain 20–30 Pd particles and Pr4O7 particles<20 . The catalysts obtained have two-order of magnitude higher specific activity in the CH3OH synthesis than Pd/C.  相似文献   

15.
The rate constants for Br(2P1/2) and Br(2P3/2) atoms in the reaction Br+CH3FHBr+CH2F in photobromination of CH3F have been determined. Their ratio is 10–(2.6±0.5) exp(10100±1000/RT) in the temperature range of 60–200 °C.
Br(2P1/2) Br(2P3/2) Br+CH3FHBr+CH2F CH3F. 60–200 °C 10–(2,6±0,5) exp (10100±1000/RT).
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16.
The thermodynamic parameters for the interaction of Cu2+, Ni2+, Co2+, Cd2+, andAg+ with the new title ligand have been determined by titration calorimetry in 50% THF–methanol (V/V) at 25 °C.Ag+ exhibited remarkably higher complexation selectivity.Ag+ and several transition metal ions have been transportedusing this ligand as carrier in a bulk liquid membrane. CompetitiveAg+–M2+ transport studies have also beencarried out for the same system. In this membrane transport study, high transport of Ag+ was observed in both single and competitiveAg+–M2+ transport studies. The complexformation of N,N-bis[o-(diphenylphosphino)benzylidene]ethylenediamine (P2N2) with silver,[Ag(P2N2)] (NO3), (1) is reported. Complex 1 has been characterized by X-ray crystallography. 1 ismonoclinic, space group P21/n (No. 14), with cell dimensionsa = 13.398(4) , b=12.577(5) , c = 21.521(4) , =100.14(2) , V = 3570(2) 3 and Z = 4.  相似文献   

17.
The catalytic reduction of nitrogen oxides (NO, N2O and NO2) by carbon monoxide over NiO has been studied in the temperature range from 200 to 500°C. The reaction of NO2 with CO is much faster than that of NO with CO. The former reaction in the presence of a 3–4-fold excess of oxygen proceeds at a significant rate. In the temperature range studied, NO2 decomposes to N2 and O2.
200–500°C (NO, N2O NO2) NiO. NO2 CO NO CO. NO2 CO 3–4- . NO2 N2 O2.
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18.
The interaction of the cobalt phosphine complexes Co(N2)(PPh3)3, HCo(N2)(PPh3)3 and H3Co(PPh3)3 with styrene yields mono and dinuclear complexes identified by the ESR method. A paramagnetic complex, Co(PPh3) (styrene)2, is one of the intermediates in the catalytic hydrogenation of styrene.
Co(N2)(PPh3)3, HCo(N2)(PPh3)3 H3Co(PPh3)3 . , Co(PPh3) ()2.
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19.
Thermogravimetry and simultaneous DTA were used to investigate the phenomena of adsorption, desorption and surface reactions on solid catalysts. The measurements were carried out with NaX and X-type ion-exchanged zeolites and silica-alumina gels (Ketjen) treated with sodium hydroxide in the presence of carbon dioxide. On the basis of the quantitative results it is possible to give an interpretation of the surface phenomena and to establish the existence of various active centres on the surfaces of the catalysts. In the case of the adsorption of carbon dioxide on X-type zeolites, the quantity of carbon dioxide adsorbed is much smaller on ion-exchanged zeolites than on NaX.
Zusammenfassung Thermogravimetrie und simultane DTA wurden zur Untersuchung der Adsorptions-, Desorptions-Erscheinungen und Oberflächenreaktionen an festen Katalysatoren eingesetzt. Die Messungen wurden and NaX und Zeolithen des Typs X sowie an Silika-Aluminiumoxidgelen Ketjen durchgeführt, welche mit Natriumhydroxid in Gegenwart von Kohlendioxid behandelt worden waren. Aufgrund der quantitativen Ergebnisse ist es möglich eine Deutung der Oberfiächenerscheinungen zu geben und die Existenz verschiedener aktiver Zentren an der Katalysatorenoberfläche nachzuweisen. Im Falle der Adsorption von Kohlendioxid an Zeolithen des Typs X ist die Menge des adsorbierten Kohlendioxids am Ionenaustauscher viel niedriger als am NaX.

Résumé Application de la TG et de l'ATD simultanées à l'étude des phénomènes d'adsorption, de désorption et de réactions de surface sur des catalyseurs solides. Les mesures ont été effectuées avec des zéolites échangeuses d'ions de type NaX et X ainsi qu'avec des gels Ketjen silice-alumine traités par NaOH en présence de CO2. Les résultats quantitatifs permettent de donner une interprétation des phénomènes de surface et d'établir l'existence de divers centres actifs à la surface des catalyseurs. Dans le cas de l'adsorption de CO2 sur les zéolites de type X, la quantité de CO2 adsorbé est beaucoup plus faible que sur les zéolites de type NaX.

DTA , . - NaX X - « », . . X, - , NaX.
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20.
Within the prospect of quantifying the geometrical dissimilarity of molecular models on the basis of a thermodynamical formalism, the algebra of stereogenic pairing equilibria is reviewed and applied to molecular geometry: developing Rassat's proposition, an interaction energy of two figures F and F is taken as proportional tod H Emphasis>/2 (F, F), whered H denotes the Hausdorff distance. IfG is a group of rotations in E n the geometrical version of the general equation (E) of the chemical algebra defines a distance extensionD p(F,F) ofd H(F,F), which is independent of the orientations of F and F, and where the coefficientp is interpreted as the reciprocal of a temperature-like parameter:p 1/T. At K (p = ), no formal entropy contributes to the definition of the uniform distanceD . At K (p = 0), the discrimination between homo- and hetero-pairing of figures by the harmonic distance Do is averaged over orientation states. Temperature-dependent chirality measuresc p are derived fromD p, andc is analogous to Mislow's chirality measure. If T and oT are normalized enantiomorphic triangles with coincident centroids inE 2,c p(T) =D p (T, T) is calculated forp = 0 andp = , and discussed for 0 <p < . Finally, the Hausdorff interaction model is putatively related to energy profiles versus dihedral angle inmeso- anddl-molecules.  相似文献   

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