Scalable Green Synthesis of Robust Ultra-Microporous Hofmann Clathrate Material with Record C H Storage Density for Efficient C H /C H Separation.

Developing porous materials for C H /C H separation faces the challenge of merging excellent separation performance with high stability and easy scalability of synthesis. Herein, we report a robust Hofmann clathrate material (ZJU-75a), featuring high-density strong binding sites to achieve all the above requirements. ZJU-75a adsorbs large amount of C H with a record high storage density of 0.818 g mL , and concurrently shows high C H /C H selectivity (54.2) at 296 K and 1 bar. Single-crystal structure analysis unveil that the high-density binding sites in ZJU-75a not only provide much stronger interactions with C H but also enable the dense packing of C H . Breakthrough experiments on gas mixtures afford both high separation factor of 14.7 and large C H uptake (2.79 mmol g ). This material is highly stable and can be easily produced at kilogram-scale using a green synthesis method, making it as a benchmark material to address major challenges for industrial C H /C H separation.