General kinetic model and prediction of critical effects

General kinetic model and prediction of critical effects 

One of the most essential problems in the construction of a general kinetic model is to describe both the high-vacuum and the normal pressure regions (we have discussed this problem more fully in Sect. 1). 

Today a detailed model for the complex reaction of CO oxidation over metals can be constructed only in the high-vacuum region where there exist mechanisms obtained on the basis of the direct observation of the catalyst state and its surface composition. But of applied significance is also the region of pressures above 1 Torr for which such measurements are practically absent in the literature. 

Nevertheless even now it is possible to apply the qualitative investigation of kinetic models corresponding to simple model mechanisms, not only for a description of the established experimental kinetic curves, but also for the prediction of kinetic regularities in the parametric region that has not been examined by experiment [165]. 

Let us illustrate this by the example of critical effects. For CO oxidation these effects were observed quite often at normal pressures but extremely rarely in the high-vacuum region (see Sect. 1). Meanwhile the above calculated data show that the critical effect can also be observed in this region. Steady-state diagrams (Figs. 2 and 3) demonstrate intervals for the conditions under which critical effects do exist. This contradiction has existed until recently. 

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