Zeolite Y, ZSM-5 and mordenite powder were used to obtain the adsorption curves of ethanol vapor. And spheres made from those powders were used to obtain the temperature profiles as well as the adsorption curves. A nonisothermal model considering heat effect in the sphere and both micro- and macropore diffusion was established from those experiments. Macropore diffusivity and linear isothermal constant were represented as functions of temperature.
It was shown by simulation that as the diffusion rate was more controlled by macropore diffusion rather than by micropore diffusion, the adsorption rate was more rapid and the maximum temperature in the pellet during adsorption became higher. And adsorption rate of nonisothermal model was more rapid than isthermal model, but as temperature decreased to its initial value, that is, the temperature of the surroundings, the adsorption rate increased more slowly toward equilibrium. As a result, the time required to reach equilibrium from the start of adsorption were nearly the same in both cases.
Data fitting of adsorption rate with model showed a good agreement but a little discrepancy at higher uptake. The discrepancy seemed to be originated from the assumptions of linear isotherm and/or concentration independent diffusivity in cases of zeolite Y and ZSM-5, while it was caused by the one dimensional pore structure in case of mordenite.
