Highly efficient separation of linear and branched C4 isomers with a tailor‐made metal–organic framework

Abstract Separation of linear and branched isomers is of great commercial significance but still one of the energy‐intensive and challenging processes in petrochemical industry. Here, we for the first time report a tailor‐made metal–organic framework, ZU‐36‐Co (also termed GeFSIX‐3‐Co, GeFSIX = GeF 6 2− , 3 = pyrazine), for the separation of both C4 linear/branched olefins ( n −/ iso ‐C 4 H 8 ) and paraffin isomers ( n −/ iso ‐C 4 H 10 ). With the pore size ranged between 3.82–5.25 Å, ZU‐36‐Co traps a large amount of n ‐C 4 H 8 (2.35 mmol/g) and n ‐C 4 H 10 (2.20 mmol/g) with iso ‐C 4 H 8 and iso ‐C 4 H 10 excluded. The molecular exclusion effect illustrates the significance of tailor‐made pore window size for gas separation. To our knowledge, ZU‐36‐Co exhibits the highest n −/ iso ‐C 4 H 8 uptake ratio (13.8) and superior n −/ iso ‐C 4 H 10 separation performance compared with the state‐of‐the‐art materials and sets a benchmark for the separation of linear and branched C4 isomers. This excellent molecular exclusion effect of ZU‐36‐Co was further confirmed by mixed gas breakthrough tests.