Effect of particle size distribution on catalyst effectiveness

Abstract

When calculating the effectiveness factor for a distribution of catalyst particle sizes, the average particle radius defined by Eq. (12) should be employed. Then, in the asymptotic limit of strong intraparticle diffusion resistance all plots of effectiveness factor vs Thiele modulus, regardless of the shape of the particle size distribution, will be identical to the plot for a uniform particle size. Outside the asymptotic limit one must take into account the distribution of particle sizes, Eq. (5), for precise calculations. However, an analysis based upon the log-normal distribution indicates that the use of an average particle radius is quite reasonable for values of the parameter β less than about 0.5 (Fig. 1). If errors of the order of 32% can be tolerated, then calculations based upon the average radius can be employed for values of β less than unity.