Atomic-Level Design of Electron-Rich Framework Oxygens Enhances Trace CO 2 Capture in Mordenite Zeolite Monoliths

The development of efficient physisorbents for trace CO 2 capture remains a critical challenge. Moving beyond conventional metal–CO 2 interaction strategies, we demonstrate a powerful alternative pathway through atomic-level engineering of zeolite oxygen electronic states. Incorporating Ce into the mordenite (MOR) framework generates electron-rich lattice oxygens and spatially polarized O δ− –Ce δ+ –O δ− domains within the channels. These unique electronic features endow the resulting Ce-MOR with exceptional CO 2 uptake, even at high Si/Al ratios (∼8). Spectroscopic analyses and density functional theory (DFT) calculations reveal that strong Ce 4f–O 2p orbital coupling redistributes electron density, creating robust trapping sites. The electron-rich O δ− atoms serve as primary binding centers, synergizing with adjacent Ce δ+ to enable dual CO 2 adsorption pathways: C δ+ (CO 2 )···O δ− (framework) and O δ− (CO 2 )···Ce δ+ . Furthermore, by assembling Ce-MOR crystals into a binder-free monolith, we achieve enhanced mass transport and mechanical stability, translating the intrinsic adsorption advantages of Ce-MOR into superior dynamic CO 2 capture performance under realistic flow conditions. This work offers a novel perspective on designing practical, high-efficiency physisorbents by tailoring electron-rich anionic centers and integrating them into scalable monolithic architectures.