Modulation of the Pore Environment of Zr-MOFs by Alkoxy Engineering for Efficient Natural Gas Purification

Adsorptive separation by porous materials holds great potential for natural gas purification, yet precise pore regulation for performance optimization still faces difficulties. This study optimizes the pore environment of metal-organic frameworks (MOFs) via alkoxy engineering for efficient natural gas purification. We designed and successfully synthesized three Zr-MOF materials (UiO-68-MeOMe, UiO-68-MeOEt, and UiO-68-MeOPr), systematically investigating the influence of the alkoxy chain length on the MOF pore structure and thus natural gas separation performance. UiO-68-MeOMe has the highest specific surface area. At 298 K and 1 bar, it exhibits a high C3H8 adsorption capacity of 261.8 cm3 g-1. Compared with UiO-68-MeOEt and UiO-68-MeOPr, it exhibits the highest separation potential, a comprehensive metric that integrates both adsorption capacity and selectivity, with values of 7.2 mmol g-1 for C3H8/CH4 and 1.6 mmol g-1 for C2H6/CH4. UiO-68-MeOMe delivers the most outstanding overall performance by optimally balancing the enhanced host-guest interactions against the structural defects arising from alkoxy chain modification. Breakthrough experiments further confirm that UiO-68-MeOMe exhibits good separation performance and shows remarkable cycling stability. Grand Canonical Monte Carlo simulations further verify that UiO-68-MeOMe displays preferential adsorption toward C3H8 and C2H6 over CH4. This work offers a straightforward ligand-engineering route to tailor MOF and adsorbate interactions, guiding the rational design of advanced adsorbents for natural gas purification.