Fabrication of robust zirconium metal-organic frameworks for efficient C₃H₆/C₂H₄ separation

Adsorption separation of C₃H₆/C₂H₄ mixtures has garnered significant attention owing to its immense potential to reduce energy consumption. To further advance this process, the key lies in the construction of adsorbents with excellent separation performance. Herein, we report the synthesis of a zirconium-based metal–organic framework (MOF) material, UiO-68-2CH₂OCH₃, which was isostructural to UiO-68 and possesses a high specific surface area of up to 3133 m²·g⁻¹ together with high pore volume up to 1.63 cm³·g⁻¹, attributes that enable its high capacity for C₃H₆. The C₃H₆ adsorption capacity of UiO-68-2CH₂OCH₃ reached 238.7 cm³·g⁻¹ at 298 K, which is comparable to the top-performing MOFs, and the C₃H₆/C₂H₄ (v: v = 50:50) selectivity at 298 K and 100 kPa was calculated to be 6.6. The corresponding separation potential can be up to 5.0 mmol·g⁻¹. Dynamic breakthrough experiments on UiO-68-2CH₂OCH₃ confirm its efficient separation of C₃H₆/C₂H₄ under actual dynamic conditions, with the breakthrough time remaining virtually unchanged over five cycles. The GCMC simulations further reveal that the more C-H···π interactions and hydrogen bond interactions with methoxymethyl groups in UiO-68-2CH₂OCH₃ facilitate the affinity for C₃H₆. In addition, UiO-68-2CH₂OCH₃ displayed fine stability across a range of pH conditions. Therefore, this project not only provides a promising candidate for the separation of the C₃H₆/C₂H₄ mixture but also provides empirical guidance for the construction of high-performance adsorbents.