Intrapellet and Bulk Species Concentrations

30-1 INTRAPELLET AND BULK SPECIES CONCENTRATIONS 30-1.1 Porous Catalytic Pellet 

Since contributions from convective transport are negligible in a porous catalyst, one begins with the steady-state mass transfer equation that includes diffusion and multiple chemical reactions for component i (i.e., see equations 9-18 and 27-14)  

Equation (30-3) is integrated over an arbitrary control volume V within the catalytic pores via Gauss s law  

Pick s law for diffusional mass flux j, peuet within the catalytic pores is written in terms of a concentration gradient, molecular weight, and the effective diffusivity 

The intrapellet mass transfer resistance for component i is directly proportional to the molar density difference on the left side of (30-8). It should be emphasized that the stoichiometric relations given by (30-5) and (30-8) are applicable throughout the entire volume of the pellet when one chemical reaction governs the rate of conversion of reactants to products. 

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