Efficient separation of CO from CH and N in an ultra-stable microporous metal-organic framework.

The efficient separation of CO from CH and N is essential for the upgrading of biogas and reducing carbon emissions in flue gas, but is challenging in the energy industry. Developing ultra-stable adsorbents with high CO adsorption performance in adsorption separation technology is deemed an effective solution for the separation of CO/CH and CO/N. Herein, we report an ultra-stable yttrium-based microporous metal-organic framework (Y-bptc) used for the efficient separation of CO/CH and CO/N. The single-component equilibrium adsorption capacity of CO reached 55.1 cm g at 1 bar and 298 K, while the adsorption capacity of CH and N was almost negligible and thus resulted in a high adsorption ratio for CO/CH (45.5) and CO/N (18.1). GCMC simulations revealed that the μ-OH functional groups distributed in the pore cage of Y-bptc provide stronger adsorption sites for CO hydrogen-bonding interactions. The relatively lower heat of adsorption of CO (24 kJ mol) further reduces the desorption regeneration energy consumption. Dynamic breakthrough experiments using Y-bptc for the separation of CO/CH (1/1) and CO/N (1/4) mixtures could obtain high purity (>99%) CH and N, and the CO dynamic adsorption capacities reached 52 and 31 cm g, respectively. More importantly, the structure of Y-bptc remained intact under hydrothermal conditions. The high adsorption ratio, low heat of adsorption, great dynamic separation performance, and ultra-stable structure of Y-bptc make it one of the candidate adsorbents suitable for the separation of CO/CH and CO/N in real-world applications.