Construction of Molecular Fans in Metal-Organic Framework to Overcome Diffusion Resistance in Molecular-size-matched Pores for Trace Benzene Capture

Molecular size-matched pores of adsorbents provide strong adsorptive forces for benzene, but high diffusion resistance. Overcoming the diffusion resistance within molecular size-matched pores is essential to efficient capture of trace benzene from indoor air or industrial exhaust gas, but challenging. Herein, we report a robust Fe-based metal-organic framework (ZJU-701) featuring hierarchical micropores (5.8 ± 0.9, 10.2 ± 2.3, and 21.2 ± 1.4 Å) and molecular fans with 1,4-naphthylene as rotors between micropores. ZJU-701 shows adsorption rate constant of 6.0×10⁻ ³ min⁻¹ and adsorption capacity of 2.05 mmol·g⁻¹ for benzene at P/P₀ =0.001 and 298 K, surpassing other benchmark adsorbents. Strikingly, ZJU-701 exhibits only 8.2% loss of dynamic adsorption capacity for trace benzene as the gas flow rate increases from 0.03 to 0.12 m·s⁻¹, much lower than other benchmark adsorbents (23.3%~83.1%). This work pioneers the dynamic pore-engineering with molecular fans to overcome diffusion resistance within molecular size-matched pores and balance adsorption rate and capacity for trace gas capture.