High-temperature kinetics

In kinetics studies, as in mass spectrometry, data reduction can be helpful before starting a detailed analysis. A typical application in which data reduction is of value is high-temperature kinetics. Reactions in flames are complex, so study of these reactions is challenging not just experimentally but also... 

Baulch D.L., Duxbury J., Grant S.J., and Montague D.G. (1981) Evaluated high temperature kinetic data. /. Phys. Chem. Ref. Data 10 (suppl. 1). 

As discussed in Chapter 5, kinetic theories predict that the preexponential factor should have a temperature dependence that manifests itself in curved Arrhenius plots if the reactions are studied over a sufficiently broad temperature range. This is the case for OH-al-kane reactions, where there has been great interest in the high-temperature kinetics for combustion systems. Table 6.2 also shows the temperature dependence for the OH reactions in the form k = BT"e c/l, where C = E.JR and in the form recommended by Donahue et al. (1998a). 

We are basically interested in heterogeneous, high temperature kinetics. At high temperatures, the chemical reactions occur as fast as the reactants can get together, like ionic solution reactions. Hence, we are concerned mainly with how fast the species can get from one part of the system to another. These transport processes are the bottlenecks... 

Estimation of tensile property degradation rates at room temperature (20°C) from the high temperature kinetic data was accomplished by application of the Arrhenius equation ... 

The salt decomposes during fusion60 and therefore the melting point can only be determined approximately. The decomposition is exothermic and yields only RbCl and 02 as the final products. The high-temperature kinetic data can be fitted by various rate equations, all of which yield an Arrhenius activation energy near 293 K,95 consistent with the loss of one oxygen as the rate-determining step ... 

Reaction Path During Quench. Unfortunately, there is a sparsity of high-temperature kinetic data for the H—C—N system. Hence, one is unable to predict with certainty the reaction path followed as the atomic-species H, C, and N, are cooled from 15,000°K. to 500°K. in 10 msec., for example. After an examination of the experimental results in the succeeding sections, it may be possible to infer the important steps in the reaction sequence. 

With = 1 and mP = 2, the low-temperature rate constant is then determined mainly by for a given value of E. The low-temperature and temperature independent kinetic isotope effect k /k is, therefore, determined by which is obtained experimentally at high temperatures. In other words, kg /kg and the high-temperature kinetic isotope effects cannot be varied independently of each other, which is not in agreement with experimental data. This effect can be associated with heavy atom tunneling during the H-transfer. The tunneling mass is increased and the low-temperature H/D isotope effect decreased. 

Most of the studies show that some of the kinetic expressions valid for high-temperature WGSR are also valid for low-temperature WGSR. Shchibiya et al. found a kinetic expression similar to high-temperature kinetic equation based on Cu0/Zn0/Cr203 [2b]. Later Uchida et al. [49] confirmed that the kinetic expression derived from redox mechanism accurately correlated the kinetic data obtained with the Cu-Zn catalysts. Cherednik et al. [50] proposed other equation for a commercial catalyst (2u0/Zn0/Cr203... 

Jarrold, M.F., Ijiri, Y., Ray, U., Interaction of silicon cluster ions with ammonia annealing, equilibria, high temperature kinetics, and saturation studies. J. Chem. Phys. 1991, 94, 3607. 

Key words isobutylene, in situ ATR-FTIR, BCI3, high temperature, kinetics... 

Bustamante F, Enick RM, Cugini AV, Killmeyer RP, Howard BH, Rothenberger KS, Ciocco MV, Morreale BD, Chattopadhyay S, Shi S. (2004) High-temperature kinetics of the homogeneous reverse water-gas shift reaction. AICHEJ, 50 1028-1041. 

Catoire L., Swihart M.T. High-temperature kinetics of AICI3 decomposition in the presence of... 

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