Kinetics of elementary processes at the surface of a solid

1965 ◽  
Vol 1 (1) ◽  
pp. 40-43
Author(s):  
V. I. Osherov
Keyword(s):  
Elementary Processes ◽  
Kinetics Of

Kinetic study by controlled-transformation rate thermal analysis of the dehydroxylation of kaolinite

Clay Minerals ◽  
1998 ◽  
Vol 33 (2) ◽  
pp. 269-276 ◽  
Author(s):  
P. Dion ◽  
J.-F. Alcover ◽  
F. Bergaya ◽  
A. Ortega ◽  
P. L. Llewellyn ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Vapour Pressure ◽  
Reaction Rate ◽  
Diffusion Mechanism ◽  
Transformation Rate ◽  
Elementary Processes ◽  
Precise Control ◽  
First Order ◽  
Temperature And Pressure ◽  
Kinetics Of

AbstractAlthough the kinetics of the dehydroxylation of kaolinite have been widely studied, there is no definitive explanation of its mechanism due to its dependence on a variety of parameters. In this study, the dehydroxylation of kaolinite has been studied using controlled-transformation rate thermal analysis (CRTA), allowing precise control of the reaction rate, and thus of both the temperature and pressure above the sample. Modelling of the experimental results obtained by CRTA as well as those from TEM and MAS-NMR show that two elementary processes (diffusion and firstorder) can occur in competition. At the start of the decomposition the diffusion mechanism is predominant, but as the reaction progresses, the first-order mechanism prevails. It would seem that the importance of each process depends, in particular, on the presence of defects as well as on the local vapour pressure.

On the Kinetics of Elementary Processes of Pressure Solution

1998 ◽  
Vol 152 (4) ◽  
pp. 667-683 ◽  
Author(s):  
V. Kruzhanov ◽  
B. Stöckhert
Keyword(s):  
Pressure Solution ◽  
Elementary Processes ◽  
Kinetics Of

Elementary processes and kinetics of H2plasmas for different technological applications

2002 ◽  
Vol 11 (3A) ◽  
pp. A7-A25 ◽  
Author(s):  
M Capitelli ◽  
R Celiberto ◽  
F Esposito ◽  
A Laricchiuta ◽  
K Hassouni ◽  
...  
Keyword(s):  
Elementary Processes ◽  
Kinetics Of

The mechanism of the acetaldehyde pyrolysis

1967 ◽  
Vol 297 (1450) ◽  
pp. 365-375 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Main Chain ◽  
Small Contribution ◽  
Methyl Radicals ◽  
Additional Source ◽  
Elementary Processes ◽  
Order Coefficient ◽  
Kinetics Of Formation ◽  
Low Pressures ◽  
Kinetics Of

Previous work on the acetaldehyde pyrolysis is shown to be vitiated by the presence, in the acetaldehyde, of impurities, mainly ethanol and crotonaldehyde. The reaction has been reinvestigated with the use of acetaldehyde, prepared from paraldehyde, which is free from these and other impurities. On the basis of a study of the kinetics of formation of the major products (methane and carbon monoxide) and of a number of minor products (hydrogen, acetone, propionaldehyde, ethane and ethylene) a reaction mechanism is proposed. This includes all of the reactions in the original Rice-Herzfeld scheme, together with a number of other elementary processes, in particular CH 3 + CH 3 CHO → CH 4 + CH 2 CHO. The decomposition of the radical CH 2 CHO into CH 2 CO and H provides an additional source of hydrogen, the rate of production of which is therefore not a measure of the rate of the initiation process. Acetone is believed to arise mainly by the reaction CH 3 + CH 3 CHO → CH 3 COCH 3 + H, and only to a negligible extent by the combination of CH 3 and CH 3 CO. The main chain-ending step is concluded to be CH 3 + CH 3 → C 2 H 6 , with a small contribution from CH 3 + CH 2 CHO → CH 3 CH 2 CHO. The work provides further evidence for the falling off, at low pressures, of the second order coefficient for the combination of methyl radicals. Rate constants for various elementary processes are deduced from the rates of formation of the various products, and are shown to be consistent with values obtained directly.

The rates of elementary processes in the chain reaction between hydrogen and oxygen III. Kinetics of the combination of hydrogen atoms with nitric oxide

1967 ◽  
Vol 297 (1451) ◽  
pp. 520-533 ◽  
Keyword(s):  
Ground State ◽  
Third Body ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Chain Reaction ◽  
Elementary Processes ◽  
The Third ◽  
Electronically Excited ◽  
Kinetics Of ◽  
Related Process

A detailed study of the kinetics of the raction H + NO + M = HNO + M + 49.9 kcal/mole (1) shows that all the third bodies examined except H 2 O give similar relative efficiencies for the formation of ground state ( 1 A ') and electronically excited ( 1 A ") HNO. The overall rate constants found at 293°K (in cm 6 mole -2 s -1 x 10 -16 ) are: Ar, 1.11 ± 0.15; H 2 , 2.07 ± 0.18; CO 2 , 2.26 ± 0.23; N 2 O, 2⋅45 ± 0⋅44; SF 6 , 3.96 ± 0.46; H 2 O, 6.8 ± 1.2. For the reaction D + NO + Ar = DNO + Ar a rate constant of (1.28 ± 0.21) x 10 16 cm 6 mole -2 s -1 was obtained. The relative third body efficiencies in reaction (1) were less similar to the closely related Process H + O 2 + M = HO 2 + M + 47.1 kcal/mole than to the reaction O + NO + M = NO 2 + M + 73.2 kcal/mole.

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