They exhibit a much shorter mass transfer zone and a vastly improved overall adsorption kinetic constant compared to a packed bed. However, this depends on the exact geometry of the considered laminate, foam, monolith, or pellet being compared. The drawback of structured adsorbents is a lower density of active adsorbent. We found that the pellet density impacts productivity greatly because it is directly related to the density of the active adsorbent. Despite this, Rezaei and Webley showed that a PSA process still favours laminates in terms of productivity.