CONCENTRATION-DEPENDENT MICROPORE DIFFUSION ANALYZED BY MEASURING LABORATORY ADSORBER DYNAMICS .1. STUDY OF THE ADSORBER FLOW BEHAVIOR

The flow behaviour of an isobaric laboratory adsorber is investigated. This investigation is the basis for a correct analysis of the concent ration-dependent micropore diffusion as presented in Part II. Exit fun ctions of the inactive adsorber (containing sorption inert particles) were measured as the response to non-ideal step functions. The experim ental exit functions are well fitted by the dispersion as well as the series-of-stirred-tanks (SST) model. However, only the more time-consu ming dispersion model is found to describe the real local mixing chara cteristics of the adsorber. This property of the flow model is necessa ry because the non-linear sorption dynamics are highly sensitive to va riations in the local mixing states, even if these variations do not a ffect the exit function (residence-time distribution) of the inactive adsorber. A computation study reveals that this sensitivity is repeale d by (1) measuring desorption (instead of adsorption) behaviour and (2 ) utilizing the short-bed technique. By implementing the latter condit ions it is possible to use the simple and computer time-sparing SST mo del for the correct determination of the non-linear micropore diffusio n mechanism.