Heat Effects in a Catalyst Pellet The Nonisothermal Effectiveness Factor

3 Heat Effects in a Catalyst Pellet The Nonisothermal Effectiveness Factor 

Illustration 4.9 considered the model that describes the isothermal diffusion and reaction in a catalyst pellet. Solution of that model yields tiie reactant concentration profile within the pellet, which is then converted by integration 

In general the heat of reaction, which is of the order of 100 kj/mol, caimot be ignored, and the mass balance must then be complemented by an appropriate shell energy balance. That balance must consider the heat conducted in and out of the shell, as well as the heat generated or consmned within the pellet. 

We assume the same slab geometry and first-order reaction as before and consider the reaction to be exothermic, which is the more common case. The following formulation is then obtained  

This expression is supplemented by the mass balance given in Illustration 4.9 in which the rate constant /c, is now a function of temperature. We repeat it here for completeness  

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