Kinetic Analysis of Deactivation by Coke Formation

The data required for a kinetic formulation of the deactivation of the main reaction are probably best collected in a differential reactor. Some extrapolation to zero time is required when the reaction rate of the main reaction cannot be observed at zero coke content. The procedure can be hazardous with very fast coking, of course. In their study of butene dehydrogenation, Dumez and Froment [1976] were able to take samples of the exit stream of stabilized operation of the fixed bed reactor after 2 minutes, while the observations extended over more than 30 minutes. 

A specific and very useful equipment for coking rate studies is the electrobalance, used by Takeuchi et al. [1966] in their study of the dehydrogenation of isobutene, by Ozawa and Bischoff [1968] in their investigation of coking associated with ethylene cracking, by De Pauw and 

A convenient type of equipment for studies of this type is the tapered element oscillating microbalance (TEOM), developed by Patashnick and Rupprecht [1980] and shown in Fig. 5.3.3-2. The advantage of this equipment is that the full amount of gas is flowing through the element containing the catalyst bed, which is brought to oscillation. The evolution of the amount of 

Recycle micro-electrobalance for catalyst deactivation studies [Beirnaert et al., 1994]. 

As in any kinetic analysis, care has to be taken with diffusion influences, as already mentioned in Section 5.3.2.1. Assuming that these have been eliminated in the experimentation, a modern approach for the experimental work and data analysis could be as represented in Fig. 5.3.3-3. 

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Kinetic Analysis of Deactivation by Coke Formation Example 5.3.3.A Application to industrial Processes Coke... 

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