Value analysis of the kinetic model

Now let us schematically represent the stages laid down in the value analysis of the kinetic model for formaldehyde oxidation in the presence of carbon oxide (11). First let us choose the target functional characterizing the change in the concentration of the initial substances formaldehyde, carbon oxide (II) and oxygen... 

Defining the Optimal Values for Controlling Parameters by Means of the Value Analysis of the Kinetic Model... 

Besides, as is already known (see Seetion 3.4) the value analysis of the kinetic model promotes increasing its prognostic capability, thus broadening possible interval of the adequate effect of the control parameter u(f) (equation 4.26). 

The value analysis of the kinetic models, and as a consequence, the ranking of individual chemical transformations by their contribution into the resultant indicator of a chemical multisteps reaction, provides a basis which enables to retrieve information on the reactivity of the reacting particles. For example, it is possible to identify what chemical reactions involving an initial reagent and its intermediates play an important role and then to forecast how the change in the molecular structure of a reaction species will influence on the result of a complex chemical process. 

Summari2dng, let us note one more remarkable fact emerging from the results of the value numerical analysis of the kinetic model for a-methylacrolein oxidation. The magnitudes for the chain carriers are categorized into two classes by their importance... 

An analogous analysis of the solution copolymerization of styrene with acrylonitrile in toluene leads [283] to the same conclusion concerning the choice of the kinetic model as for the bulk copolymerization of these monomers. The applicability of the penultimate model (2.3) was also convincingly proved [283] for the given system, and the estimated values of its four parameters (2.4) (see Table 6.8) were found to be slightly different from the ones obtained in the bulk copolymerization [283], The experimental values of the fractions of all six triads, determined by means of NMR, in the solution copolymerization products, practically do fit the theoretical plots of the triad fractions vs conversion, which were calculated on the basis of the kinetic parameters presented in Table 6.8. 

The value of the stability constant is not accepted. An analysis of the method used to determine the parameters of the kinetic model made in Appendix A indicates that the method used to calculate is in error. 

We suppose that the value method of analyzing the reaction kinetic models may enhance considerably the efficiency of a similar procedure, as it improves the capabilities to retrieve information from the kinetic models of reactions. On the other hand, this method enables to rank the steps, and accordingly, the rate constants of the kinetic model, by their sensitivity in describing specific experimental results. This will permit to determine acceptability of applying the rate constants with a prescribed accuracy. One can look through the analysis of imcertainty of the kinetic model due to the uncertainty of rate constant of steps in references [58,65,66]. 

Thus, by the example of the kinetic model for oxidation of formaldehyde in the presence of carbon oxide (II) it may be concluded that value analysis is a quite reliable method to reduce the reaction mechanisms that results in the identification of the base kinetic model for a chemical transformation. 

Two main reasons of this phenomenon were disclosed by the value analysis of the reaction kinetic model. 

The solution space of the kinetic model includes the electrical current as a function of the transient potential, normalized to the scan rate, in addition to coverages of different surface oxide species considered. Using parameters obtained from the fits of CV scans, steady-state coverages as a function of potential in the limit of 0 can be evaluated. Figure 3.19 compares these coverages with coverage values obtained by analysis of EC-XPS data (Wakisaka et al., 2010). Among parameters obtained... 

This chapter has discussed the analysis of reactors for step-growth polymerization assuming the equal reactivity hypothesis to be valid. Polymerization involves an infinite set of elementary reactions under the assumption of this hypothesis, the polymerization can be equivalently represented by the reaction of functional groups. The analysis of a batch (or tubular) reactor shows that the polymer formed in the reactor cannot have a polydispersity index (PDI) greater than 2. However, the PDI can be increased beyond this value if the polymer is recycled or if an HCSTR is used for polymerization. A comparison of the kinetic model with experimental data shows that the deviation between the two exists because of (1) several side reactions that must be accounted for, (2) chain-length-dependent reactivity, (3) unequal reactivity of various functional groups, or (4) comphca-tions caused by mass transfer effects. 

The kinetic analysis of the sigmoid pH-rate profile will yield numerical estimates of the pH-independent parameters K, k, and k". With these estimates the apparent constant k is calculated using the theoretical equation over the pH range that was explored experimentally. Quantitative agreement between the calculated line and the experimental points indicates that the model is a good one. A further easy, and very pertinent, test is a comparison of the kinetically determined value with the value obtained by conventional methods under the same conditions. 

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