High-stability pillar-layered Zn/ZnCd-MOFs with optimized pores for efficient methane purification

Efficient methane (CH$_4$) purification is critical for the full utilization of clean natural gas in the petrochemical industry. Compared with conventional energy-intensive low-temperature distillation, adsorptive separation using porous metal–organic frameworks (MOFs) represents a more energy-efficient and high-performance alternative. Herein, we synthesized a series of layer-based Zn- and Zn/Cd-MOFs (LIFM-260–265) by regulating metal nodes and pillar ligands of different sizes to tailor their topologies and pore dimensions. Of these materials, the porous MOFs with pillar-layer structures (LIFM-263–265) enable simultaneous removal of ethane (C$_2$H$_6$) and propane (C$_3$H$_8$) from a CH$_4$/C$_2$H$_6$/C$_3$H$_8$ ternary mixture. Among them, LIFM-265 delivers the highest productivity of high-purity (>99.8%) CH$_4$ (7.92 mmol g−1) based on single breakthrough curve tests, outperforming its analogues LIFM-263 and LIFM-264. Theoretical simulations reveal that the optimal pore structures and aromatic surface environments of LIFM-263–265 promote favorable interactions with C$_2$H$_6$ and C$_3$H$_8$ molecules, thus enhancing selective adsorption of C2/C3 hydrocarbons. This work provides valuable insights for the rational design of pillar-layered MOFs for methane purification.