Dynamical adsorption in fixed bed

The behavior of an adsorbent fixed-bed had been investigated for irreversible equilibrium when the adsorption rate is limited by internal diffusion. Breakthrough curves equations has been established for spherical or cubic sorbent particles considering axial dispersion. It has been found out a linear law between the extrapolated breakthrough time and the inverse of adsorbate flowrate. That allows the evaluation of internal diffusion and axial dispersion coefficients.The breakthrough curves of propylene on 13X molecular sieves are interpreted accurately when it is admitted that the adsorption rate is limited by the action of combined internal and external difrusions and when the axial diffusion is taken into account.When the axial diffusion is neglected, the breakthrough curves can be also computed but the coefficients of mass transfer chosen for a good fitting do not agree with those predicted by classical formula.