Enhancing CO₂ capture efficiency using optimized 3D-Printed structured adsorbents

3D-printed CO₂ adsorbents hold significant promise for industrial applications but face challenges such as reduced efficiency due to binder use and limitations in scalability. This study builds on our previously developed binder-free 3D printing platform using brominated poly(2,6-dimethyl-1,4-phenylene oxide) (Br-PPO). Leveraging its advantages of high printability with low-viscosity liquid ink, post-printing flexibility, and high gas selectivity and stability, in this study, we aim to improve CO₂ capture performance while maintaining compatibility with post-printing processes. Our approach employs three key strategies: (1) increasing the bromination level of PPO to improve intrinsic CO₂ adsorption capabilities, (2) optimizing 3D adsorbent structures to enhance surface-to-volume ratios and packing density without disrupting post-printing processes, and (3) modularizing 3D-printed adsorbent building blocks to address scalability challenges. Increasing PPO bromination to 67 % improved CO₂ adsorption capacity by 40 %, driven by the higher density of substituted amines introduced during post-printing amine-grafting. Structural optimization through customized mesh designs demonstrated that adsorbents with unevenly spaced filaments (MHh) achieved comparable CO₂ capture efficiency to evenly spaced designs (MH), despite higher porosity, underscoring the role of structural optimization in enhancing adsorption efficiency while minimizing mass. Dynamic flow tests with 3D-printed adsorbent assemblies further validated the platform's effectiveness, demonstrating efficient CO₂ capture at low flow rates (3 mm/min) without pressure drops and superior performance compared to activated carbon at equivalent volumes. These findings highlight the potential of 3D-printed adsorbents with tailored geometries as scalable solutions for CO₂ capture, particularly in compact, energy-efficient applications such as advanced air purification systems and industrial gas separation processes.