Kinetics of Metal Atom Oxidation Reactions

The CeO2/CeO2−δ redox system occupies a unique position as an oxygen carrier in chemical looping processes for producing solar fuels, using concentrated solar energy. The two-step thermochemical ceria-based cycle for the production of synthesis gas from methane and solar energy, followed by CO2 splitting, was considered in this work. This topic concerns one of the emerging and most promising processes for the recycling and valorization of anthropogenic greenhouse gas emissions. The development of redox-active catalysts with enhanced efficiency for solar thermochemical fuel production and CO2 conversion is a highly demanding and challenging topic. The determination of redox reaction kinetics is crucial for process design and optimization. In this study, the solid-state redox kinetics of CeO2 in the two-step process with CH4 as the reducing agent and CO2 as the oxidizing agent was investigated in an original prototype solar thermogravimetric reactor equipped with a parabolic dish solar concentrator. In particular, the ceria reduction and re-oxidation reactions were carried out under isothermal conditions. Several solid-state kinetic models based on reaction order, nucleation, shrinking core, and diffusion were utilized for deducing the reaction mechanisms. It was observed that both ceria reduction with CH4 and re-oxidation with CO2 were best represented by a 2D nucleation and nuclei growth model under the applied conditions. The kinetic models exhibiting the best agreement with the experimental reaction data were used to estimate the kinetic parameters. The values of apparent activation energies (~80 kJ·mol−1 for reduction and ~10 kJ·mol−1 for re-oxidation) and pre-exponential factors (~2–9 s−1 for reduction and ~123–253 s−1 for re-oxidation) were obtained from the Arrhenius plots.

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Gas phase interaction with catalytic oxidation reactions

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1972.0006 ◽

1972 ◽

Vol 326 (1565) ◽

pp. 215-227 ◽

Cited By ~ 7

Keyword(s):

Carbon Dioxide ◽

Maleic Anhydride ◽

Catalytic Oxidation ◽

Gas Phase ◽

Major Part ◽

Oxidation Reactions ◽

Mixed Gas ◽

Kinetics Of ◽

Oxidation Of Benzene ◽

Homogeneous Decomposition

Studies of the catalytic oxidation of benzene to maleic anhydride and carbon dioxide over vanadia/molybdena catalysts show that the major part of the reaction involves interacting gas and gas-solid processes. The results are consistent with a mechanism in which a benzeneoxygen adduct is formed catalytically, desorbs and then reacts to give maleic anhydride entirely in the gas phase. On the basis of this proposed mechanism, the kinetics of individual reactions have been investigated in some depth. The over-oxidation of maleic anhydride has been found to be not significant under the conditions of reaction. The kinetic relationships governing the homogeneous decomposition of the adduct and the oxidation of the adduct to maleic anhydride and to carbon dioxide have been established. The results show that essentially all of the anhydride originates from mixed gas-solid/gas reaction while substantial amounts of carbon dioxide are produced entirely catalytically.

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Oxidation of Olefins Representing Some Structural Units of GR-S

Rubber Chemistry and Technology ◽

10.5254/1.3543370 ◽

1952 ◽

Vol 25 (1) ◽

pp. 21-32 ◽

Cited By ~ 1

Author(s):

W. C. Warner ◽

J. Reid Shelton

Keyword(s):

Phenyl Group ◽

Kinetic Mechanism ◽

Oxidation Reactions ◽

Chain Reaction ◽

Instantaneous Rate ◽

Initial Oxygen ◽

Oxidation Of Olefins ◽

A Minor ◽

The Relationship ◽

Kinetics Of

Abstract Three olefins were oxidized in the liquid phase with molecular oxygen to determine the kinetics of the oxidation reactions and the relationship to oxidation of rubber. The instantaneous rate of oxidation was found to be related to the analytically determined olefin and peroxide concentrations by the equation : Rate=k (unreacted olefin)(peroxide), where rate equals moles of oxygen per mole of original olefin per hour and the parentheses represent molarities. Presence of a phenyl group was found to affect k, but only in a minor way, indicating that the same fundamental kinetic mechanism applies in both aromatic and aliphatic olefins. The data are consistent with the general kinetic mechanism of Bolland involving oxygen attack at the alpha-methylenic group. However, it appears probable that initial oxygen attack can also occur at the double bond, resulting in the formation of a peroxide biradical, which may then react with other olefin molecules, initiating the usual chain reaction mechanism.

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Chiral [Mo3S4H3(diphosphine)3]+Hydrido Clusters and Study of the Effect of the Metal Atom on the Kinetics of the Acid-Assisted Substitution of the Coordinated Hydride: Mo vs W

Inorganic Chemistry ◽

10.1021/ic100381u ◽

2010 ◽

Vol 49 (13) ◽

pp. 5935-5942 ◽

Cited By ~ 31

Author(s):

Andrés G. Algarra ◽

Manuel G. Basallote ◽

M. Jesús Fernández-Trujillo ◽

Marta Feliz ◽

Eva Guillamón ◽

...

Keyword(s):

Metal Atom ◽

Kinetics Of

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Kinetics of uncatalysed and catalysed oxidation reactions of α-hydroxy acids by periodate

Proceedings of the Indian Academy of Sciences - Section A ◽

10.1007/bf03182120 ◽

1978 ◽

Vol 87 (4) ◽

pp. 87-94

Author(s):

Subas C Pati ◽

Y Sriramulu

Keyword(s):

Oxidation Reactions ◽

Hydroxy Acids ◽

Catalysed Oxidation ◽

Kinetics Of

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ChemInform Abstract: Kinetics of Neutral Transition-Metal Atoms in the Gas Phase: Oxidation Reactions of Ti(a3F) from 300 to 600 K.

ChemInform ◽

10.1002/chin.199345024 ◽

2010 ◽

Vol 24 (45) ◽

pp. no-no

Author(s):

M. L. CAMPBELL ◽

R. E. MCCLEAN

Keyword(s):

Transition Metal ◽

Gas Phase ◽

Oxidation Reactions ◽

Metal Atoms ◽

Transition Metal Atoms ◽

Phase Oxidation ◽

Gas Phase Oxidation ◽

Kinetics Of

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Further investigations on the kinetics of gaseous oxidation reactions

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1930.0156 ◽

1930 ◽

Vol 129 (810) ◽

pp. 284-299 ◽

Cited By ~ 27

Keyword(s):

Rate Of Change ◽

Chain Mechanism ◽

Oxidation Reactions ◽

Chain Reactions ◽

Oxidation Of Methane ◽

Simple Order ◽

Oxidation Of Hydrocarbons ◽

Rate Of Reaction ◽

A Chain ◽

Kinetics Of

Investigation of the kinetics of the oxidation of ethylene and of benzene showed that these reactions are peculiar in the following respects. First, the relation between the rate of reaction and concentration is such that the reactions possess no simple “order,” though the nearest integral value for the order is about the third of fourth. The rate increases very rapidly with increasing hydrocarbon concentration, but is relatively little influenced by oxygen; under some conditions oxygen may have a retarding influence. Secondly, the reactions can be slowed down by increasing the surface exposed to the gases. This indicates that the oxidation occurs by a chain mechanism. Thirdly, the rate of change of pressure accompanying the oxidation only attains its full value after an induction period, during which evidently intermediate products are accumulating. Accepting the fact that the oxidations are probably chain reactions, the relation between rate and concentration shown that the chains are much more easily propagated when the intermediate active molecules encounter more hydrocarbon than when they encounter oxygen. Following the view of Egerton, and consistently with previous work on the combination of hydrogen and oxygen, the working hypothesis adopted is that some intermediate peroxidised substance is responsible for the propagation of the chains. This being so, the question arises whether the peculiarities found in the oxidation of hydrocarbons will also be found with substances already containing oxygen. To investigate, therefore, the influence of chemical configuration on the mechanism of oxidation reactions the following series of compounds has been studied CH 4 CH 3 OH HCHO which represent the stages through which Bone and others have shown the oxidation of methane to occur.

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