Acetylene production typically generates carbon dioxide (CO₂) as the main by-product, and separating the two gases is notoriously challenging due to their similar properties. Current separation methods, such as solvent extraction or low-temperature distillation, are energy-intensive and come with significant safety risks, particularly due to explosive nature of C₂H₂. Therefore, developing a safer and more efficient method to separate acetylene from CO₂ and store acetylene securely is crucial.

Recent research by Professor Sihai Yang from Peking University and Professor Martin Schröder from the University of Manchester introduces a promising new approach for the purification and safe storage of C₂H₂. Lixia Guo, a BMS research fellow at Peking University, is the first independent author. The material, MFM-190 (NO₂), demonstrates outstanding performance in selectively adsorbing C₂H₂, with a C₂H₂ adsorption capacity of 216 cm³/g at 298 K and 1.0 bar, significantly exceeding the performance of other reported MOF materials. Furthermore, dynamic separation experiments confirmed its effectiveness in separating C₂H₂ from CO₂ at room temperature.

Figure 1. Adsorption data of C₂H₂/CO₂ separation and C₂H₂ storage

We also investigated the host-guest interaction using in-situ neutron powder diffraction. We discovered the crucial role of divalent copper vacancies and free -NO₂ groups in enhancing the adsorption of C₂H₂. The results showed that C₂D₂ (deuterated acetylene) binds at multiple well-defined sites in the framework, with one particularly strong interaction occurring at the Cu(II) vacancy site.

Figure 2. Neutron powder diffraction analysis of the adsorption sites of C₂H₂ in MFM-190(NO₂)

The study received support from the National Natural Science Foundation of China, the Beijing National Research Center for Molecular Sciences, EPSRC (EP/I011870, EP/V056409), and the University of Manchester, among others.

Find the link for more information：doi.org/10.1002/anie.202417183