Honeycomb-like Mordenite Zeolite Monoliths with Hierarchical Porosity for Promoting Direct Air Capture of CO 2

Porous physical adsorbents with low cost hold great promise for direct air capture (DAC) of CO 2, offering a solution to the prohibitive costs of current technologies. However, traditional microporous adsorbents face severe diffusion limitations and sluggish adsorption kinetics under trace CO 2 conditions due to their narrow pore architectures. Here, we present a protozeolite-assisted kinetic regulation strategy to synthesize monolithic mordenite (MOR) zeolites with honeycomb-like, hierarchical micro-meso-macroporous networks. The hierarchical structure provides rapid mass transfer channels, while the binder-free monolithic architecture avoids pore occlusion and ensures efficient diffusion. Benefiting from enhanced site accessibility and optimized diffusion pathways, the honeycomb-like MOR exhibits a CO 2 breakthrough adsorption capacity of 1.15 mmol g –1 at 400 ppm, significantly surpassing the breakthrough performance of conventional zeolitic materials. Combined Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations elucidate the hierarchical pore-driven enhancement of CO 2 diffusion coefficients ( D s ) and establish the structure-diffusion-adsorption interplay. This work provides critical insights into the role of pore architecture in trace CO 2 capture and delivers guidelines for designing the next generation of high-capacity DAC adsorbents that align with the principles of green chemistry and sustainable engineering.