THE ROLE OF REACTION PRODUCTS IN THE SILVER-CATALYZED OXIDATION OF ETHYLENE

1960 ◽  
Vol 38 (11) ◽  
pp. 2256-2268 ◽  
Author(s):  
Kenneth E. Hayes
Keyword(s):  
Carbon Dioxide ◽  
Ethylene Oxide ◽  
Initial Rate ◽  
Flow System ◽  
Oxygen Exchange ◽  
Reaction Products ◽  
Exchange Reactions ◽  
Kinetics Of ◽  
Catalyzed Oxidation

Initial-rate studies of the kinetics of the silver-catalyzed oxidation of ethylene oxide and carbon dioxide in a flow system have been made. It was found that, using carefully purified reactants, the effect of added carbon dioxide was to suppress the formation of ethylene oxide only. The initial rate of the formation of ethylene oxide is given by the equation[Formula: see text]where r0 is the initial rate in the absence of CO2; m, n, and k are constants with m + n = 1.These results together with the results of oxygen exchange reactions between O18 and C2H4O16, CO216 and H2O16 are interpreted mechanistically.

scholarly journals The mechanism of the catalytic oxidation of ethylene - I. Experiments using a flow system

1946 ◽  
Vol 188 (1012) ◽  
pp. 92-104 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Ethylene Oxide ◽  
Catalytic Oxidation ◽  
Flow System ◽  
Oxidation Reactions ◽  
Direct Oxidation ◽  
Rate Of Reaction ◽  
Reaction Proceeds ◽  
Products Of Reaction ◽  
Kinetics Of

Experiments have been made using a flow system to determine the mechanism of the catalytic oxidation of ethylene on a silver catalyst. The effects of time of contact of the gases with the catalyst, gas concentration, and temperature have been investigated. The products of reaction are ethylene oxide, and carbon dioxide and water. There appear to be two processes whereby the carbon dioxide is formed: (1) by direct oxidation of the ethylene not via ethylene oxide, and (2) by the further oxidation of the ethylene oxide. The isomerization of ethylene oxide to acetaldehyde by the catalyst in the absence of any oxygen has also been examined. By comparison with the oxidation of ethylene oxide, it has been shown that this latter reaction proceeds to a large extent, and possibly entirely, through a preliminary isomerization of the ethylene oxide to acetaldehyde. The rate of oxidation of acetaldehyde is extremely rapid and no trace of acetaldehyde is found during the oxidation of ethylene or of ethylene oxide. Ethylene oxide forms on the catalyst an involatile deposit, which is oxidized away by oxygen, so that during oxidation reactions the quantity of it on the catalyst is kept low. The kinetics of the oxidation of ethylene, i.e. rate of reaction proportional to the oxygen concentration and slightly dependent on the ethylene pressure, are consistent with the view that ethylene reacts with oxygen adsorbed on the catalyst and that the slowest step in the whole series of reactions is the rate of adsorption of the oxygen. An energy of activation of about 27 kcal. was found for the production of ethylene oxide, and slightly less for the production of carbon dioxide and consumption of oxygen.

THE SILVER CATALYZED OXIDATION OF ETHYLENE: III. KINETICS OF ETHYLENE OXIDE OXIDATION

1954 ◽  
Vol 32 (4) ◽  
pp. 432-442 ◽  
Author(s):  
A. Orzechowski ◽  
K. E. MacCormack
Keyword(s):  
Ethylene Oxide ◽  
Initial Rate ◽  
Oxidation Mechanism ◽  
Kinetic Studies ◽  
Main Step ◽  
Direct Oxidation ◽  
Flow Rates ◽  
Rate Determining Step ◽  
Kinetics Of ◽  
Catalyzed Oxidation

A flow type apparatus was used for kinetic studies of the silver catalyzed oxidation of ethylene oxide (EtO) by oxygen at 274 °C. Using N2 as diluent the concentrations of O2 and ethylene oxide were varied independently from 9.9 to 79% and 2.35 to 9.4% respectively while a total pressure of 1 atmosphere was maintained. Flow rates were varied to give a range of contact times varying from 0.06 to 0.25 sec. It was shown that EtO is oxidized without previous dissociation into C2H4 and O2. The dependence of the initial rate of oxidation of EtO on reactant concentrations excludes isomerization of EtO (to acetalde hyde) as a main step in its oxidation, and a direct oxidation mechanism is suggested. The results of a few experiments to determine the extent of isomerization of EtO to acetaldehyde in the absence of oxygen are presented. No steady state could be achieved but the results may be used semiquantitatively to support the belief that isomerization is not the rate determining step in the oxidation of ethylene oxide.

The role of Tween 80 and SDS in the kinetics of semi-clathrate hydrates formation for carbon dioxide capture from flue gas

2021 ◽  
pp. 1-15
Author(s):  
Anton Petukhov ◽  
Artem Atlaskin ◽  
Maria Sergeeva ◽  
Sergey Kryuchkov ◽  
Dmitry Shablykin ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Flue Gas ◽  
Carbon Dioxide Capture ◽  
Tween 80 ◽  
Clathrate Hydrates ◽  
Kinetics Of

A Study of the Kinetics of the Basic Zinc Carbonate Formation Reaction

1975 ◽  
Vol 30 (9-10) ◽  
pp. 665-668 ◽  
Author(s):  
M. F. O'Connor
Keyword(s):  
Carbon Dioxide ◽  
Water Vapour ◽  
Water Layer ◽  
Water Vapour Pressure ◽  
Formation Reaction ◽  
Zinc Carbonate ◽  
Carbonate Formation ◽  
Carbon Dioxide Pressure ◽  
Kinetics Of

A study of the kinetic parameters involved in the formation of basic zinc carbonate by the action of carbon dioxide and water vapour on zinc oxide has been undertaken. A contracting sphere model is used to explain the reaction but its applicability is dependent upon the carbon dioxide pressure used. Water vapour pressures close to saturated water vapour pressure are necessary for the reaction to proceed and the role of the necessary near-liquid surface water layer in the absorption reaction is discussed.

THE KINETICS OF THE DECOMPOSITION REACTIONS OF THE LOWER PARAFFINS: IV. THE ROLE OF FREE RADICALS IN THE DECOMPOSITION OF n-BUTANE

1939 ◽  
Vol 17b (3) ◽  
pp. 105-120 ◽  
Author(s):  
E. W. R. Steacie ◽  
H. O. Folkins
Keyword(s):  
Nitric Oxide ◽  
Ethylene Oxide ◽  
Complete Suppression ◽  
Radical Chain ◽  
Decomposition Reactions ◽  
Maximum Inhibition ◽  
A Chain ◽  
Kinetics Of ◽  
Oxide Inhibition

An investigation has been made of the inhibition of free radical chain processes in the decomposition of n-butane by the addition of nitric oxide. The method was to initiate chains in butane at low temperatures by means of ethylene oxide, and then to investigate the efficiency of nitric oxide in suppressing these chains.It was found that nitric oxide is not completely efficient as a chain breaker, inasmuch as sensitization by ethylene oxide persisted in the presence of large amounts of nitric oxide. It is therefore concluded that maximum inhibition of organic decomposition reactions by nitric oxide does not in all cases correspond to complete suppression of chains, and hence the real chain length in such reactions may be greater than that inferred from the results of the nitric oxide inhibition method.

Kinetics and mechanistic study of the ruthenium(III) catalyzed oxidative deamination and decarboxylation of L-valine by alkaline permanganate

2001 ◽  
Vol 79 (12) ◽  
pp. 1926-1933 ◽  
Author(s):  
Dinesh C Bilehal ◽  
Raviraj M Kulkarni ◽  
Sharanappa T Nandibewoor
Keyword(s):  
Ionic Strength ◽  
Alkaline Medium ◽  
Activation Parameters ◽  
Solvent Polarity ◽  
Mechanistic Study ◽  
Reaction Products ◽  
Order Dependence ◽  
Alkaline Permanganate ◽  
Kinetics Of ◽  
Catalyzed Oxidation

The kinetics of ruthenium(III) catalyzed oxidation of L-valine by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction between permanganate and L-valine in alkaline medium exhibits 2:1 stoichiometry (KMnO4:L-valine). The reaction shows first-order dependence on the concentration of permanganate and ruthenium(III) and less than unit-order dependence on the concentrations of L-valine and alkali. The reaction rate increases both with an increase in ionic strength and a decrease in solvent polarity of the medium. Initial addition of reaction products did not significantly affect the rate. A mechanism involving the formation of a complex between catalyst and substrate has been proposed. The activation parameters were computed with respect to the slowest step of the mechanism.Key words: oxidation, L-valine, catalysis, ruthenium(III), kinetics.

THE SILVER CATALYZED OXIDATION OF ETHYLENE: I. SLOW PROCESSES ON THE CATALYST SURFACE

1954 ◽  
Vol 32 (4) ◽  
pp. 388-398 ◽  
Author(s):  
A. Orzechowski ◽  
K. E. MacCormack
Keyword(s):  
Ethylene Oxide ◽  
Reaction Temperature ◽  
Catalyst Surface ◽  
Flow System ◽  
Catalyst Activity ◽  
Reference State ◽  
Silver Catalyst ◽  
Kinetic Measurements ◽  
Catalyzed Oxidation ◽  
Oxygen Atoms

In the silver catalyzed oxidation of ethylene or ethylene oxide (EtO), the silver catalyst activity measured under constant standard conditions in a flow system was found to be dependent on the conditions of previous catalyst treatment such as reaction temperature and reactant composition. The results are explained on the basis of slow establishment of equilibrium respecting fixation of stably sorbed oxygen atoms and surface products of oxidation. It is emphasized that in view of the slow processes observed, the kinetic measurements must be punctuated by frequent stabilizing check runs in order to maintain the catalyst in the same reference state.

Kinetics of the oxidation of ethane by nitric oxide over manganese(III) oxide

1981 ◽  
Vol 59 (14) ◽  
pp. 2232-2238
Author(s):  
R. A. Ross ◽  
C. Fairbridge
Keyword(s):  
Nitric Oxide ◽  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Atmospheric Pressure ◽  
Flow System ◽  
Oxide Formation ◽  
Catalyst Structure ◽  
X Ray ◽  
Apparent Activation Energies ◽  
Kinetics Of

The catalytic reaction between ethane and nitric oxide over manganese(III) oxide has been investigated in a continuous flow system from 673 to 573 K at atmospheric pressure. The products of catalysis were nitrogen, carbon dioxide, nitrous oxide, and water. The rate of nitrous oxide formation was constant over this temperature region, while the apparent activation energies for nitrogen and carbon dioxide formation increased from 32 ± 4 and 22 ± 4 kJ mol−1, respectively, at 573 to 613 K, to 78 ± 4 and 63 ± 4 kJ mol−1 between 613 and 673 K. The kinetic results were best described by the rate equation:[Formula: see text]The surface mechanism appears to be complex and has been interpreted by a scheme involving interaction of the reactants in an absorbed layer. Both nitric oxide and ethane are believed to be involved further in subsequent steps. Infrared evidence indicates the possibility of a surface nitrate intermediate consistent with the mechanistic proposal. Scanning electron microscopy and X-ray powder diffraction techniques were used to assess the catalyst structure.

Vulcanization of Elastomers. 30. Kinetics of the Decrease of Sulfur Concentration during Vulcanization

1961 ◽  
Vol 34 (2) ◽  
pp. 606-628 ◽  
Author(s):  
Walter Scheele ◽  
Martin Cherubim
Keyword(s):  
Initial Rate ◽  
Order Reaction ◽  
Usual Sense ◽  
Complex Nature ◽  
Reaction Products ◽  
Sulfur Concentration ◽  
First Order ◽  
Synthetic Rubber ◽  
Kinetics Of ◽  
Characteristic Trend

Abstract The present discussion deals with the explanation and critical analysis of the kinetics of the decrease in concentration of sulfur in accelerated and unaccelerated vulcanizations of natural and synthetic rubber. A marked distinction is made between the time law and the dependence on concentration of the rate of decrease of sulfur, since there is lack of agreement between them, both in accelerated and unaccelerated vulcanizations, which indicates the complex nature of vulcanization. In unaccelerated vulcanization, the sulfur concentration drops, at all temperatures and independent of the concentration, according to a time law with exponent n=0.6. On the other hand, the dependence on concentration of the initial rate of sulfur decrease proceeds according to a first order reaction. These relations make it seem probable that sulfur decrease involves a process which is catalyzed by reaction products. In accelerated vulcanization, the reduction of concentration of sulfur also is expressed by a time law with the exponent n<1, and this too is independent of temperature and concentration of reactants (sulfur and accelerator). However, the concentration dependence of the rate of sulfur decrease cannot be expressed by a power law, so that we find no order of reaction in the usual sense. We attempt to explain the characteristic trend of the initial rate of sulfur decrease with sulfur concentration at constant accelerator content, or with accelerator concentration at constant sulfur content, by assuming that the vulcanization takes place through intermediate compounds. The pertinent theoretical conceptions are disclosed and critically examined and the attempt is made to show the extent to which they may be brought into accord with the experimental data.

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