ANALYSIS OF ZLC TECHNIQUE FOR DIFFUSIVITY MEASUREMENTS IN BIDISPERSE POROUS ADSORBENT PELLETS

The zero length column (ZLC) technique has been successfully used to m easure diffusivities in zeolite crystals. However, in industrial appli cations pellets with bidisperse structure, containing macropores and m icropores (crystals), are commonly used as zeolites. In this paper, a model of ZLC desorption curves for bidisperse porous materials is deve loped. Model equations are analytically solved for linear systems. A n umerical solution of model equations using orthogonal collocation is a lso used. The various regions of control (macropore diffusion, micropo re diffusion) are identified. Simulations allow the choice of operatin g conditions for the ZLC technique. Procedures for the analysis of ZLC experiments are reported. Copyright (C) 1996 Elsevier Science Ltd.