Design of ultra-stable Yttrium-organic framework adsorbents for efficient methane purification and storage

As a cleaner, cheaper and globally distributed fuel, methane (CH4) has considerable environmental, economic, and political advantages over petroleum as a source of energy for the transportation sector. However, it is still challenging to achieve efficient CH4 purification from CO2 or C2-hydrocarbons and its following storage for practical application, where the design of high-performance adsorbent materials is critical. Here we report two isostructural ultra-stable double-interpenetrated yttrium-based metal–organic frameworks (MOFs), SNNU-324 and SNNU-325, which are rationally designed by a topology-guided strategy with 1,3,5-tris(4-carboxyphenyl)benzene (BTB) and 2,4,6-tris(4-carboxyphenyl)- 1,3,5-triazine (TATB) as tritopic linkers and [Y3(OH)2(H2O)4(COO)8] and [Y4O2(H2O)4(COO)8] clusters as secondary building units (SBUs), respectively. Notably, thanks to the high-connectivity and double-interpenetrated architectures, SNNU-324–325 MOFs exhibit extra-high thermal, water and pH stability. Low-pressure gas adsorption, IAST selectivity and breakthrough curves reveal a remarkable CO2/C2-hydrocarbons over CH4 separation performance of SNNU-324 and SNNU-325. In particular, the breakthrough interval times can reach up to 20, 45, 38, and 61 min g−1 for CO2/CH4, C2H2/CH4, C2H4/CH4 and C2H6/CH4 with 2 mL min−1 for SNNU-325 at 298 K, which exceed most well-known MOF adsorbents. High-pressure gas uptake experiments further indicate SNNU-324 and SNNU-325 are promising CH4 storage adsorbents. Specially, at room temperature, SNNU-325 exhibits a total CH4 uptake of 120 cm3 cm−3 under 35 bar and deliver capacity of 65/78 cm3 cm−3 under 35/65 bar, which are comparable with most top-level methane storage MOFs.