Adsorptive dehydration of ethanol using 3A zeolite: an evaluation of transport behaviour in a two-phase zeolite pellet

This paper dwells into the diffusional transport of water inside a pelleted zeolites wherein the transport behavior in binder phase as well as in the zeolite phase is explored. It is noted that both the phases contributes towards the separation process. A new variant of bi-disperse diffusion model is proposed for the water transport inside the adsorbent pellets. The equilibrium uptake of water is separately encountered in the binder and zeolite phases using a dual site Henry-Langmuir isotherm and a thermodynamically consistent correlation is developed for the boundary layer concentration of the zeolite phase with respect to the concentration within the binder phase. Adsorption kinetics measurements are reported for various adsorbent sizes and process temperatures, and their influence on transport diffusivity is explored. The proposed model prediction is in good agreement with the experimental observation in which the pellet diffusion controls the overall transport behaviour.