Changes in reaction rate for different kinetic models

Conclusions

The material presented indicates the expediency of the preliminary analysis of kinetic data based not only on the reaction rate as function of the degree of conversion, proposed earlier [1], but also based on other parameters of the process. The analysis of the relationships between reaction rate and temperature, dilution (or total pressure), and composition of the initial mixture leads to curves, from the specific form and direction of which it is possible to derive the actual form of the kinetic equation and the ratio of its constants. This treatment is complementary to the analysis of the form of the kinetic equation and refers to the “initial level” [1] of the kinetic relationship at a composition of the reaction mixture or a degree of conversion kept constant while changing each of the other parameters. Based on the relationship between the “level” of the kinetic function and its form, the analysis provides the information which reduces the possible ambiguity in the interpretation of kinetic data.

Evidently this analysis does not encompass all cases of multidirectional reactions, described sometimes by complex and laborious kinetic equations. It can be carried out, however, in each particular case. Of particular interest is the case where the denominator of the total kinetic equation (2) is a product of polynomials with the corresponding exponents, due to inhomogeneity of the catalyst surface [9]. An approximative analysis of the kinetic equation can be obtained with a denominator approximated with a polynomial carrying a certain exponentl.

The examples cited indicate that such a preliminary analysis of kinetic functions derived directly from experimental data are useful and necessary for the design of kinetic models, by offering a less ambiguous interpretation.