Rational Pore Design of a Cage-like Metal-Organic Framework for Efficient CH/CO Separation.

Considering the importance of CH in industry, it is of great significance to develop porous materials for efficient CH/CO separation. Besides the high selectivity, the CH adsorption capacity is another vital factor in CH/CO separation. However, the "trade-off" between these two factors is still perplexing. Rational pore design of metal-organic frameworks (MOFs) has been proven to be an effective way to solve the above problem. In this work, we have appropriately combined three kinds of strategies in the design of the MOF (), i.e., the introduction of open metal sites, construction of cage-like cavities, and adjustment of moderate pore size. As anticipated, exhibits both outstanding CH adsorption capacity and high CH/CO selectivity. At 298 K and 100 kPa, the CH storage capacity of is 154 cm/g, while the CO uptake is only 80 cm/g. The ideal adsorbed solution theory (IAST) selectivity of CH/CO (50:50) is calculated as high as 15.5 at 298 K. More importantly, the excellent practical separation performance was verified by breakthrough experiments. In addition, the calculation of adsorption sites and relevant energy by density functional theory (DFT) provides a good explanation for the excellent separation performance and pore design strategy.