State-of-the-art packed-bed sorbent systems that rely on randomly distributed solid sorbent beads, pellets, or granules suffer from several constraints, including a limited packing density at about 64%, high pressure drop penalties, poor thermal management due to point-to-point contacts, and wall channeling leading to early breakthrough and uneven bed utilization. 3D-printed sorbent beds are envisioned to alleviate some of these challenges, particularly by addressing wall channeling and packing density limitations. However, existing 3D-printed sorbent beds are predominantly focused on small-scale structures, making it challenging to assess their system-level adsorption performance, including a conclusive determination of the presence or absence of the wall channeling effect. Moreover, prior 3D-printed sorbent structures exhibit limited packing densities, often substantially below those attainable with packed beds filled with beads. In this study, a large-scale 3D-printed zeolite-13X bed with a packing density exceeding the theoretical limit of conventional packed spherical-bead beds is developed to evaluate its system-level adsorption performance. Through detailed breakthrough sorption experiments comparing centerline and mixed outlet breakthrough curves, it is demonstrated, for the first time, that a 3D-printed sorbent bed can indeed eliminate the wall channeling effect. Also, the experimental results indicate that increasing the inlet air velocity shortens the breakthrough time due to enhanced adsorption rates; however, it elongates the axial dispersion length of the mass transfer zone, leading to reduced bed utilization at a target breakthrough percentage, as revealed by time derivatives of the centerline breakthrough curves in the spatial domain. Additionally, elevating the inlet CO 2 concentration decreases the breakthrough time owing to the greater CO 2 partial pressure potential and simultaneously shortens the axial dispersion length of the mass transfer zone, thereby improving bed utilization. Furthermore, at a similar packing density, the 3D-printed sorbent bed exhibits a lower pressure drop penalty compared to a conventional packed bed. Insights gained from this study advance the development of next-generation 3D-printed sorbent systems for selective gas separation, with potential impacts spanning from industrial decarbonization to extraterrestrial life support systems.