Multiple-Site Engineered Metal–Organic Frameworks for Efficient One-Step Separation of Methanol-to-Olefin Products and Natural Gas

Efficient one-step adsorption separation of light hydrocarbons (LHs) from methanol-to-olefin products and natural gas is highly desirable in the petrochemical industry. However, designing adsorbents that simultaneously achieve high selectivity and capacity remains a critical challenge. Here, we report a microporous Zn-based metal–organic framework (MAC-4-F) decorated with electronegative O, N, and F trifunctional sites, which markedly enhance host–guest interactions for the selective recognition of multi-C–H-bond gases such as C 3 H 6 and C 3 H 8 . The well-defined pore environment (∼4.2 Å) and high surface area (1295.8 m 2 ·g –1 ) endow MAC-4-F with outstanding adsorption capacities of 5.0 and 4.7 mmol·g –1 for C 3 H 6 and C 3 H 8, respectively, at 298 K and 100 kPa, together with high IAST selectivity values of 9.8 (C 3 H 6 /C 2 H 4 ), 15.4 (C 2 H 6 /CH 4 ), and 91.6 (C 3 H 8 /CH 4 ). Dynamic breakthrough-desorption experiments further confirm its ability to produce high-purity C 2 H 4 (46.9 L·kg –1 ) and enrich C 3 H 6 (13.3 L·kg –1 ) in a single step, as well as recover high-purity CH 4 (349.5 L·kg –1 ) and C 3 H 8 (18.6 L·kg –1 ) from light alkane mixtures. Moreover, MAC-4-F exhibits excellent moisture stability and recyclability. Theoretical calculations reveal that the N–O–F sites reinforce multiple interactions (C–H···F/O/N, C···O–H, and C–H···π) with target molecules. Overall, this work demonstrates MAC-4-F as a highly competitive dual-function adsorbent for olefin or alkane separation from LHs, while providing new insights into the design of MOFs with electronegative-rich functional sites to overcome the capacity–selectivity trade-off in LH separation.