scholarly journals The kinetics of the combustion of methane

1936 ◽  
Vol 157 (892) ◽  
pp. 503-525 ◽  
Keyword(s):  
Induction Period ◽  
Time Curve ◽  
Kinetics Of Oxidation ◽  
Reaction Velocity ◽  
Oxidation Of Methane ◽  
Pressure Time ◽  
Reactive Mixture ◽  
A Chain ◽  
Combustion Processes ◽  
Kinetics Of

The kinetics of oxidation of methane at pressures comparable with atmospheric pressure presents many features of great interest and of considerable importance to the elucidation of the nature of combustion processes in general. The facts which have accumulated to date, though fairly precise and definite, require in some cases amplification and further study in view of the realization that combustion has the character of a chain reaction. It has been found that the temperature of ignition of methane, which lies in the region 700-800°C., is dependent on the composition and total pressure of the mixture. For equimolecular mixtures of CH 4 and O 2 , no lower limit phenomena of the kind associated with hydrogen or carbon monoxide ignition have been observed. Below the ignition limit there is a readily measurable reaction velocity, and it was shown by Fort and Hinshelwood that the pressure-time curve is comprised of three distinct parts: ( a ) an induction period of several seconds’ or minutes’ duration, during which almost no reaction can be detected; ( b ) a period of acceleration to a steady velocity, followed by ( c ) a gradual decline of the velocity to zero as the reactants are used up. Fort and Hinshelwood showed that the velocity during the reaction period was much more dependent on the pressure of methane than that of oxygen. They further established the fact that the reaction is almost completely inhibited by packing the vessel with pieces of quartz tubing. Bone and Allum showed that the most reactive mixture consists of methane and oxygen in the ratio 2:1, the induction period being shortest and the reaction velocity greatest for this proportion. It was further found that the reaction is subject to sensi­tization, small quantities of nitrogen peroxide, iodine, or formaldehyde practically removing the induction period and increasing the reaction rate. An analysis of the products of the reaction showed that it followed the general course: CH 4 + 1½ O 2 = 2H 2 O + CO. (I)

THE KINETICS OF THE OXIDATION OF GASEOUS ACETALDEHYDE

1932 ◽  
Vol 7 (2) ◽  
pp. 149-161 ◽  
Author(s):  
W. H. Hatcher ◽  
E. W. R. Steacie ◽  
Frances Howland
Keyword(s):  
Carbon Dioxide ◽  
Formic Acid ◽  
Induction Period ◽  
Reaction Vessel ◽  
Oxidation Products ◽  
Main Reaction ◽  
Chain Mechanism ◽  
Subsequent Reaction ◽  
A Chain ◽  
Kinetics Of

The kinetics of the oxidation of gaseous acetaldehyde have been investigated from 60° to 120 °C. by observing the rate of pressure decrease in a system at constant volume. A considerable induction period exists, during which the main products of the reaction are carbon dioxide, water, and formic acid. The main reaction in the subsequent stages involves the formation of peroxides and their oxidation products. The heat of activation of the reaction is 8700 calories per gram molecule. The indications are that the reactions occurring during the induction period are heterogeneous. The subsequent reaction occurs by a chain mechanism. The chains are initiated at the walls of the reaction vessel, and are also largely broken at the walls.

scholarly journals Further investigations on the kinetics of gaseous oxidation reactions

1930 ◽  
Vol 129 (810) ◽  
pp. 284-299 ◽  
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.

scholarly journals The mechanism of the catalytic oxidation of ethylene - II. Reactions between ethylene, etc. and chemisorbed oxygen monolayers

1946 ◽  
Vol 188 (1012) ◽  
pp. 105-122 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Ethylene Oxide ◽  
Low Temperatures ◽  
Adsorbed Oxygen ◽  
Silver Catalyst ◽  
Time Curve ◽  
Chemisorbed Oxygen ◽  
Pressure Time ◽  
Adsorbed Oxygen Atom ◽  
Kinetics Of

Experiments have been carried out at temperatures of 263° C and higher between oxygen adsorbed as atoms on the silver catalyst, and ethylene, ethylene oxide and acetaldehyde. The course of reaction was followed by measuring the change in pressure, and analyses of the products were made by micro-fractionation of the gases at low temperatures. In the reaction of ethylene with an oxygen-covered catalyst, the absence of an induction period in the pressure-time curve showed that oxidation of ethylene to carbon dioxide and water by a route not through ethylene oxide is possible. The reaction of acetaldehyde with the oxygenated catalyst was too fast to measure. The reactions of ethylene oxide were found to be complex, and reaction occurred both with the oxygenated and the clean catalyst. On a clean catalyst, ethylene oxide was simultaneously isomerized to acetaldehyde and converted back to ethylene and adsorbed oxygen; the acetaldehyde and adsorbed oxygen then reacted to form carbon dioxide and water. Both ethylene oxide and acetaldehyde, but not ethylene, were adsorbed with decomposition to form a non-volatile layer on the catalyst. This was composed of carbon, hydrogen and possibly oxygen, combined in indefinite and varying proportions. The kinetics of the reaction between ethylene and the adsorbed oxygen layer were measured. Throughout the course of any one reaction, the rate of oxidation to carbon dioxide was proportional to the square of the concentration of adsorbed oxygen, but the velocity constant depended on the initial concentration. The apparent energy of activation was 10 kcal. It is thought that when ethylene reacts with a single adsorbed oxygen atom, ethylene oxide is produced, and that with a pair of adsorbed oxygen atoms, intermediates such as formaldehyde are produced which react rapidly to form carbon dioxide and water.

Kinetics of oxidation of 2,4-pentanedione with Ce(IV) ions in relation to Belousov-Zhabotinskii reaction

1981 ◽  
Vol 46 (8) ◽  
pp. 1734-1739 ◽  
Author(s):  
Ľudovít Treindl ◽  
Peter Kaplán
Keyword(s):  
Induction Period ◽  
Sulphuric Acid ◽  
Reaction Step ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Inner Sphere ◽  
Belousov Zhabotinskii Reaction ◽  
Kinetics Of

Oxidation of 2,4-pentanedione with Ce(IV) ions in a solution of sulphuric acid is an inner-sphere reaction which proceeds via an intermediary complex. The reaction is of the first order with respect to both reactants, it is catalysed with H3O+ ions, and its rate diminishes with increasing concentrations of HSO4- and Ce(III) ions. According to the proposed mechanism, the rate-determining reaction step is an intramolecular redox step of the intermediary complex. The modified Belousov-Zhabotinskii reaction with 2,4-pentanedione as substrate is interesting in that oscillations with an increasing amplitude are formed after an induction period even in the absence of stirring.

Kinetic Studies in the Chemistry of Rubber and Related Materials. II. The Kinetics of Oxidation of Unconjugated Olefins

1947 ◽  
Vol 20 (3) ◽  
pp. 609-617 ◽  
Author(s):  
J. L. Holland ◽  
Geoffrey Gee
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Studies ◽  
Chain Termination ◽  
Low Oxygen ◽  
Chain Reaction ◽  
Kinetics Of Oxidation ◽  
Chain Initiation ◽  
A Chain ◽  
Kinetics Of ◽  
Direct Attack

Abstract A brief review is given of kinetic work on the oxidation of representative mono, 1,4 and 1,5 olefins. The essential process in each case is identified as a chain reaction in which hydrocarbon radicals are formed, absorb oxygen, and then react with another molecule of olefin to give a hydroperoxide and a new free radical. Three methods of chain initiation are considered: (1) direct attack of oxygen on the olefin, (2) thermal decomposition of the hydroperoxide, (3) thermal decomposition of added benzoyl peroxide. Chain termination results from interaction of two free radicals; except at low oxygen pressures, these are both peroxidic.

Solid state decomposition studies on fluoroperoxo species of transition metals. Part XI. Kinetics of isothermal and photochemical decomposition of K2TaO2F5.H2O

1982 ◽  
Vol 60 (14) ◽  
pp. 1891-1895 ◽  
Author(s):  
Gopal V. Jere ◽  
Latha Surendra ◽  
Surender M. Kaushik ◽  
Mahinder K. Gupta
Keyword(s):  
Solid State ◽  
Rate Equations ◽  
Time Curve ◽  
Solid State Decomposition ◽  
Initial Stage ◽  
Pressure Time ◽  
Peroxide Decomposition ◽  
Photochemical Decomposition ◽  
Volume Equation ◽  
Kinetics Of

The kinetics of the solid state isothermal and photochemical decompositions of K2TaO2F5.H2O have been studied by measuring the pressure of oxygen evolved in a constant volume apparatus. Isothermal decomposition of the sample was carried out in the temperature range 528 to 553 K. The reaction is predominantly deceleratory. The initial stage of the decomposition can be described by the unimolecular decay law whereas the later stage obeys the contracting volume equation. The activation energy values of the two processes are 120 and 90 kj mol−1, respectively. The photolysis of the compound at different intensities yields a pressure–time curve which can be described by the rate equations p = kt1/2. The rate of photolysis was found to be linearly dependent on intensity, indicating a monoexcitation process for peroxide decomposition.

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