共查询到20条相似文献,搜索用时 234 毫秒
1.
A. A. Medvinskii N. N. Bulgakov A. V. Kravtsov L. M. Smolova 《Reaction Kinetics and Catalysis Letters》1979,11(4):331-335
The choice of parameters according to the interacting bond method (IBM)/1/is under discussion for systems containing OH and CO-bond interacting with MgO crystal (100) plane. Various CO2 chemisorption forms on pure and hydroxylated surfaces are compared by a rough estimate of chemisorption heats.
(MBC) (1) ( (100) , OH CO. CO2 , .相似文献
2.
Molecular nitrogen and irradiation temperature are shown to affect the radiationchemical yield of O
st
–
in the radiolysis of N2O adsorbed on alumina with large surface areas and to exert no influence in the case of small surface areas of Al2O3.
, - O st – N2O, Al2O3 .相似文献
3.
A. A. Spojakina N. G. Kostova D. M. Shopov 《Reaction Kinetics and Catalysis Letters》1981,17(1-2):83-86
By means of DTA, reflectanc spectra and measurement of catalytic activity in thiophene hydrogenolysis, the effect of support (aluminium hydroxide and oxide) as well as of the order of introduction of molybdenum and cobalt compounds on the structure and catalytic surface of Co–Mo–Al2O3 catalysts is shown.
, ( ) , Co–Mo–Al2O3.相似文献
4.
H. -G. Jerschkewitz K. Wencke W. Hanke E. Schreier 《Reaction Kinetics and Catalysis Letters》1981,18(3-4):443-448
The preparation of vanadium catalysts is described using fluorine modified Aerosil as support. It is shown that modification with fluorine changes the concentration and topology of the surface silanol groups and, as a consequence, the catalytic properties.
, , . , , , .相似文献
5.
In the temperature range investigated the mild oxidation products are strongly affected by the oxygen partial pressure. The -allyl intermediates may undergo oxidation to methocrolein or dimerization to 2,5-dimethyl-1,5-hexadiene and after cycloaromatization to p-xylene.
, . - 2,5--1,5- -.相似文献
6.
《Reaction Kinetics and Catalysis Letters》1974,1(2):215-221
, - CuO–MgO. . ( - , , -) . , - .
The catalytic oxidation of propene over CuO–MgO has been compared with TPD and IR spectroscopic data. The products of extensive oxidation are shown to be formed from a strongly adsorbed propene species. Weakly adsorbed propene /-allyl or -complexes/ is an intermediate in the conversion of propene to to acrolein. The role of -complexes is not yet clear.相似文献
7.
The kinetics of Fe3+ and Cu2+ sorption from sulfate salt solutions by fibrous polyampholite have been studied.
Fe3+ Cu2+ , .相似文献
8.
The behavior of the bromate-maloni acid-cerium (III) oscillator in the presence of mercury (II)-a bromide-removing ion-can be simulated by the Oregonator model if the dynamics of bromocomplex-formation and dissociation reactions is taken into account.
- - (III) (II)- - , .相似文献
9.
The kinetics of the thermal decompositions of CaC2O4, SrC2O4 and BaC2O4 to their carbonates were studied by thermogravimetry at constant and at linearly increasing temperatures. Isothermally, the three oxalates decompose according to A1.43, R1.54 and R1 laws, respectively. Dynamically, the decompositions of the first two oxalates proceed in a similar way as under the isothermal conditions, whereas BaC2O4 decomposes according to a different law.Kinetic compensation laws were established for the decomposition of CaC2O4 and SrC2O4 under both isothermal and non-isothermal conditions. Such a compensation law is considered to result if correct kinetic model functionsF () are used when the isothermal and non-isothermal decompositions are regulated by the sameF().
Zusammenfassung Die Kinetik der thermischen Zersetzung von CaC2O4, SrC2O4 und BaC2O4 zu den entsprechenden Carbonaten wurde durch Thermogravimetrie bei konstanter und linear ansteigender Temperatur untersucht. Isotherm werden die drei Oxalate entsprechend A1.43, R1.54 bzw. R1 zersetzt. Dynamisch verläuft die Zersetzung der ersten zwei Oxalate auf ähnlichem Wege, während BaC2O4 nach einem davon verschiedenem Gesetz abgebaut wird. Kinetische Kompensationsgesetze wurden sowohl unter isothermen als auch unter nicht-isothermen Bedingungen für die Zersetzung von CaC2O4 und SrC2O4 ermittelt. Ein solches Kompensationsgesetz wird als Ergebnis eines solchen Vorgehens angesehen, bei dem richtige kinetische ModellfunktionenF() benutzt werden, wenn die nicht-isothermen Zersetzungen durch die gleichenF() bestimmt sind.
- , . , , A1.43, R1.54 · R1- , . , . F() «» , F().相似文献
10.
Kinetic parameters of thermal decomposition of compounds of general formulaM
2
I
M
II[Ni(NO2)6], whereM
I= K+, Rb+ or Cs+ andM
II= Ca2+, Sr2+ or Ba2+, were investigated on the basis of the respective thermal curves. Calculations of the reaction order and activation energy carried out by the Coats-Redfern method and by Doyle's method (modified by Zsakó) gave similar results, The reaction order is 2 for all the compounds investigated. In the group of potassium salts the activation energy increases fromM
II=Ca2+ toM
II=Ba2+. In the groups of rubidium and caesium salts, the lowest activation energy is observed whenM
II=Sr2+. Such behaviour of the nitritonickelates is explained in terms of structures and the principle of maximum density.
Zusammenfassung Die kinetischen Parameter der thermischen Zersetzung von Verbindungen der allgemeinen FormelM 2 I M II [Ni(NO2)6] (M I= K+, Rb+ oder Cs+ und MII = =Ca2+, Sr2+ oder Ba2+) wurden auf Grund der entsprechenden thermischen Kurven untersucht. Die an Hand der Coats-Redfern Methode und der durch Zsakó modifizierten Doyleschen Methode durchgeführten Berechnungen der Reaktionsordnung und der Aktivierungsenergie ergaben ähnliche Resultate. Die Reaktionsordnung ist 2 für sämtliche untersuchten Verbindungen. In der Gruppe der Kaliumsalze steigt die Aktivierungsenergie vonM II=Ca2+ in RichtungM II=Ba2+ an. In der Gruppe der Rubidium- und Caesiumsalze wird die niedrigste Aktivierungsenergie beiM II=Sr2+ beobachtet. Dieses Verhalten der Nitritonickelate wird durch die Strukturen und das Prinzip der maximalen Dichte erklärt.
1 2 II[Ni(NO2)6], I= +, Rb+Cs+,a II= 2+,8r2+2+. , - ( ), . 2. + 2+. II=S2+. .相似文献
11.
The kinetic law of ammonium perchlorate decomposition in the presence and absence of metal oxides has been studied. Sublimation has also been considered from the kinetic point of view.
. .相似文献
12.
The paper analyzes the simplest case of concentration independent deactivation of a catalyst surface in the presence of external transport limitations and accounts for the variations around the mean value of the activity of the catalysts leading to a stochastic formulation. The results reveal interesting features which would not be evident from the conventional deterministic analysis.
- , , . , .相似文献
13.
S. P. Srivastava A. K. Mittal V. K. Gupta 《Reaction Kinetics and Catalysis Letters》1981,18(3-4):415-420
Results of the kinetic studies of peroxydisulfate ion oxidation of sulfaguanidine are discussed. N,N'-bis(guanyl)azoxybenzene-p,p'-disulfonamide has been identified as the main oxidation product. On the basis of product identification and kinetic studies a radical mechanism is proposed.
. N,N'- () -, '- . , .相似文献
14.
Kinetic regularities of dimethyl sulfide synthesis from methanol and H2S in the presence of WO3/Al2O3 have been studied under gradientless conditions. A stepwise mechanism of the reaction is suggested implying that methanol methoxylates the catalyst surface, the reaction of CH3O groups with H2S yields methylmercaptan and then dimethyl sulfide, whereas that with methanol produces dimethyl ether. The kinetic equations describe fairly well the process on inhomogeneous catalyst surface.
H2S WO3/Al2O3. , , CH3O- H2S , — . , .相似文献
15.
Differential scanning calorimetry (DSC) has provided a universal tool for ascertaining the effects of preparation and thermal history on the physical characteristics of polymers. When applied to the study of nonpolymeric compounds, however, the interpretation of thermal analysis data may be complicated by the possible occurrence of chemical as well as physical transformations under thermal stress. In the present study involving 2'-deoxynucleosides, this difficulty has been resolved by utilizing a DSC-TLC combination to correlate thermal phenomena with corresponding chemical and physical changes. This combination shows great promise in extending the application of DSC to the investigation of thermal reactions.
N.S.F. Undergraduate Research Participant from SUNY College at Plattsburg, Summer 1975. 相似文献
Zusammenfassung Die Differential-Scanning-Kalorimetrie (DSC) ist besonders geeignet zum Nachweis des Einflusses der Herstellungsbedingungen und thermischen Vorgeschichte auf die Beschaffenheit von Polymeren. Beim Einsatz zur Untersuchung nicht-polymerer Verbindungen kann jedoch die Deutung der Daten der Thermoanalyse schwierig werden, da durch thermische Stresswirkung chemische sowie physikalische Unwandlungen stattfinden können. In diesem Beitrag, der sich mit 2'-Desoxynucleosiden befasst, wurde diese Schwierigkeit durch Anwendung einer Kombination von DSC und TLC behoben, welche die Korrelation thermischer Erscheinungen mit den entsprechenden chemischen und physikalischen Änderungen gestattete. Diese Kombination von DSC und TLC ist hinsichtlich der Erweiterung des Anwendungsgebiets der DSC auf die Untersuchung thermischer Reaktionen vielversprechend.
Résumé L'analyse calorimétrique différentielle (DSC) est une méthode universelle pour mettre en évidence les effets de la préparation et du passé thermique sur les caractéristiques physiques des polymères. Cependant, si on l'applique à l'étude de composés non-polymères, l'interprétation des données d'analyse thermique peut être compliquée par l'intervention possible de transformations chimiques ou physiques sous l'effet du traitement thermique. Dans la présente étude sur les désoxy-2'-nucléosides cette difficulté est éliminée en combinant la DSC et la TLC afin d'établir une corrélation entre les phénomènes thermiques qui correspondent aux changements chimiques et physiques. L'emploi combiné de ces deux méthodes semble promis à une grande extension.
. , , , . , 2- ** , - . ** .
N.S.F. Undergraduate Research Participant from SUNY College at Plattsburg, Summer 1975. 相似文献
16.
Hydrogen desorption proceeds in several temperature regions and differs by its order of magnitude and activation energy. Differential curves of adsorbed hydrogen distribution with respect to the desorption activation energy, dN/dE (E), show a considerable inhomogeneity of adsorbed atomic species and the energetic homogeneity of molecular species.
. dN/dE (E) .相似文献
17.
As a result of computer experiments with model porous networks, the factors (other than pore shape and size distribution) determining the form of the adsorption-desorption hysteresis loop have been elucidated.
, - - .相似文献
18.
M. A. Aramendía V. Borau C. Jiménez J. M. Marinas M. E. Sempere 《Reaction Kinetics and Catalysis Letters》1986,32(2):525-531
In this work we have assessed the use of sepiolites from Vallecas (Madrid, Spain) as supports of Pd catalysts applicable to the liquid-phase unblocking of amino acids and dipeptides protected by a benzyloxycarbonyl group (Z) with gaseous hydrogen. The sepiolites used have been compared with other supports employed by our team. We have also discussed the influence of the type of amino acid or dipeptide, the catalytic support and the precursor Pd salt on the unblocking rate.
(, ) Pd , , (Z), . , . , Pd .相似文献
19.
Dependence of excitation energy on the coordination of oxygen atoms in cluster models of MgO surface
Cluster models of the MgO surface have been calculated by a semi empirical method. The energies of transitions between the surface states localized on ions of definite coordination are dependent on their coordination numbers. The lower transition energies correspond to a lower coordination number of oxygen ions.
, . , , , . .相似文献
20.
A. A. Raskin 《Journal of Thermal Analysis and Calorimetry》1985,30(4):901-911
Comparative analysis of several methods for purity determination using DSC is presented. This is based on a mathematical model including the construction of theoretical melting curves for two-component systems and the calculation of recorded melting curves with the help of a set of equations describing the formation of a DSC output signal. It is shown that the true accuracy of purity determinations in the range of impurity concentrations ¯x=0.005–0.02 does not exceed 30–50%.
Zusammenfassung Eine Vergleichende Analyse verschiedener Methoden zur Reinheitsbestimmung mittels DSC wurde ausgeführt. Diese basiert auf einem mathematischen System, daß die Konstruktion theoretischer Schmelzkurven für Zweikomponentensysteme und die Berechnung von registrierten Schmelzkurven mit Hilfe einer Reihe die Ausbildung des DSC-Signals beschreibenden Gleichungen in sich einschließt. Es wird gezeigt, daß die Genauigkeit der Reinheitsbestimmungen bei Konzentrationen der Verunreinigungen von ¯X2=0.005–0.02 30–50% nicht überschreitet.
, , . , 0,005-0,02 30–50%.相似文献