In previous reports of propylene diffusion in CMS Takeda 5A, the micropore resistance controls the diffusion process [9]. No data were found for the diffusivity of propylene on CMS 4A and in general data with propylene on CMS was found only for the case of wider micropores [12] and for the case of membrane permeation [49]. Of course if the controlling step is diffusion in the micropores of CMS 5A, we should expect the same tendency in this adsorbent.