Arrhenius expression, temperature

Each k is given by an Arrhenius expression, k = A exp(—F/i T), and the fraction of the tightly bound component is a parameter. For the high temperature results in Figure 6, some charring of toluene was observed at the highest wall temperature (790°C). The fraction of toluene remaining in the bed was deterrnined from gas-phase total hydrocarbon, O2, and CO2 measurements. 

The classical experiment tracks the off-gas composition as a function of temperature at fixed residence time and oxidant level. Treating feed disappearance as first order, the pre-exponential factor and activation energy, E, in the Arrhenius expression (eq. 35) can be obtained. These studies tend to confirm large activation energies typical of the bond mpture mechanism assumed earlier. However, an accelerating effect of the oxidant is also evident in some results, so that the thermal mpture mechanism probably overestimates the time requirement by as much as several orders of magnitude (39). Measurements at several levels of oxidant concentration are useful for determining how important it is to maintain spatial uniformity of oxidant concentration in the incinerator. 

AH the models described above indicate the importance of system temperature on growth rate. Dependencies of growth kinetics on temperature are often expressed in terms of an Arrhenius expression ... 

Temperature of the system has a pronouneed effeet on the growth rate. The relation between growth kineties and temperature is often given by Arrhenius expression... 

Expression (109) appears to be similar to the Arrhenius expression, but there is an important difference. In the Arrhenius equation the temperature dependence is in the exponential only, whereas in collision theory we find a dependence in the pre-exponential factor. We shall see later that transition state theory predicts even stronger dependences on T. 

The temperature coefficient of the rate of a polymerization induced by a thermally decomposing initiator must depend according to Eq. (12) both on the temperature coefficient of kp/k] and on that of kd. Upon substituting Arrhenius expressions for each of the rate constants... 

The rate model contains four adjustable parameters, as the rate constant k and a term in the denominator, Xad, are written using the Arrhenius expression and so require a preexponential term and an activation energy. The equilibrium constant can be calculated from thermodynamic data. The constants depend on the catalyst employed, but some, such as the activation energy, are about the same for many commercial catalysts. Equation (57) is a steady-state model the low velocity of temperature fronts moving through catalyst beds often justifies its use for periodic flow reversal. 

The magnitude of Eacl for a reaction may be calculated from values of k, the rate constant (cf p. 39), determined experimentally at two different temperatures, Tj and T2, using the Arrhenius expression which relates k to T, the absolute temperature ... 

Oxidation rate constant k, for gas-phase second order rate constants, koH for reaction with OH radical, kN03 with N03 radical and ko3 with 03 or as indicated, data at other temperatures and/or the Arrhenius expression see reference ... 

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