CONCENTRATION-DEPENDENT MICROPORE DIFFUSION ANALYZED BY MEASURING LABORATORY ADSORBER DYNAMICS .2. STUDY OF THE MICROPORE DIFFUSION MECHANISM

On the basis of the flow study presented in Part I the desorption beha viour of the isobariC laboratory adsorber is investigated. The investi gation is suitable to identify the micropore diffusion mechanism of NH 3 molecules in A-type zeolite crystals. The sorption system is charact erized by the fact that the diameter of diffusing molecules is of the same magnitude is the micropore diameter. For such systems, Gutsche et al. predicted the concentration dependence of Fickian diffusivity to obey the relation D(z) = D(z0) da/dq. This relation is a special form of a more general equation derivable from transition state theory. In the present work, the concentration dependence of NH3 diffusivities is found to satisfy the above relation. With this result, an experimenta l support for the prediction of Gutsche et al. is provided.