Model Discrimination in the Dehydrogenation of -Butene into Butadiene

Example 23.d.l-l Model discrimination in the dehydrogenation of 1-butene into butadiene 

Dumez and Froment studied the dehydrogenation of 1-butene into butadiene on a chromium-aluminium oxide catalyst in a differential reactor [57]. This work is probably the first in which the experimental program was actually and uniquely based on a sequential discrimination procedure. The reader is also referred to a more detailed treatment, Dumez, Hosten, and Froment [58]. The following mechanisms were considered to be plausible  

For each of these mechanisms several rate equations may be deduced, depending on the rate-determining step that is postulated. Fifteen possible rate equations were retained, corresponding to the rate-determining steps a, fc,. ..64, c. cj, / dj, e, and ej respectively. These equations will not be given here, except the finally retained one, by way of example. 

The discrimination was based on the divergence criterion of Eq. 2.3.d.l-2 in which y is replaced by r and model adequacy criterion Eq. 2.3.d.l-4 utilized. Since the experiments were performed in a differential reactor the independent variables were the partial pressures of butene, pg, butadiene pj, and hydrogen, TTie operability region for the experiments at 525°C is shown in Fig. 1. The equilibrium surface is also represented in this figure by means of hyperbola paralle] to the PoPHj-plane and straight lines parallel to the p pni- and p po-plane respectively. Possible experiments are marked with a white dot. Experimental settings too close to the equilibrium were avoided, for obvious reasons. The maximum number of parameters in the possible models is six, so that at least seven preliminary 

Discrimination Using the Integral Method of Kinetic Analysis 

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