The internal diffusion resistance, expressed in terms of an effectiveness factor, cannot be represented in terms of a unique curve using the generalized Thiele modulus approach.
We present a general solution of the diffusion reaction problem for linear kinetics and an expression for the effectiveness factor in terms of the shape normalized Thiele modulus for a catalyst particle of arbitrary shape and with an arbitrary activity profile.
An analytical simple algebraic expression for isothermal effectiveness factor in a porous pellet is presented.
When applied to compute the concentration profile and the effectiveness factor in a porous catalyst, the conventional shooting method requires that the concentration at the catalyst center y(0) must be greater than zero to yield a nontrivial solution.
A model to calculate the actual transient effectiveness factor in spherical porous catalyst particles in gradientless reactors, where a first order reaction takes place under isothermal conditions, linear equilibrium adsorption and intraparticle diffusion control, was developed.
The model is used to demonstrate the influence of network topology (regular vs. random) and pore structure parameters (mean pore size, standard deviation pore size and network connectivity) upon the catalyst effectiveness factor in the presence of a fraction of catalyst pores that are filled with capillary condensate.
Since transport resistance limits the effectiveness factor in the reactor to values much less than unity, increasing the catalyst surface area increases its activity.
Transport resistance evaluation revealed that in spite of significant intraparticle diffusion limitation (effectiveness factor in the range of 0.01), the both resistances of mass transfer around the catalyst particle and inside the catalyst pores should be taken into account.
This paper describes a method for the determination of effectiveness factors in a monolith washcoat of non-uniform thickness.
A simplified method to calculate the effectiveness factors in irregular geometries of washcoats is presented.
