EVALUATION OF BIDISPERSE DIFFUSIVITIES AND TORTUOSITY FACTORS IN POROUS CATALYSTS USING BATCH AND CONTINUOUS ADSORBERS - A THEORETICAL-STUDY

A method has been developed to evaluate catalyst macro- and micropore diffusion and tortuosity parameters using batch and continuous adsorbers free from errors due to rates of surface diffusion and adsorption. The operator approach of D. Ramkrishna and N. R. Amundson can be used effectively to generate simple, transient mathematical solutions of batch and continuous adsorbers containing a bidisperse solid; this being used for subsequent evaluation of diffusion parameters from experiment. This theoretical study has shown that commonly used effective diffusivity models used in reaction engineering are only applicable for large pellet sizes where macropore diffusion is controlling.