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[UTSA-280] Molecular sieving of ethylene from ethane using a rigid metal–organic framework
Summary:
The authors from the University of Texas at San Antonio and the National Institute of Standards and Technology developed a rigid metal–organic framework (MOF) material UTSA-280 with molecular sieving capabilities, achieving highly selective separation of ethylene (C2H4) from ethane (C2H6) under ambient conditions.
Background:
1. To address the energy-intensive cryogenic distillation processes used for ethylene/ethane separation, previous researchers explored various MOFs with open metal sites and π-complexation, achieving some success but facing challenges such as co-adsorption of ethane and potential olefin polymerization.
2. The authors proposed a rigid MOF, UTSA-280, with precisely defined and rigid one-dimensional channels, obtaining results that demonstrate complete exclusion of ethane while selectively adsorbing ethylene.
Research Content:
1. Synthesis:
The authors synthesized UTSA-280 using calcium nitrate and squaric acid under mild conditions in water.
2. Characterizations:
1) BET surface area measurements showed a surface area of 331 m²/g and a pore volume of 0.18 cm³/g. Pore size distribution indicated dominant pore sizes of 3.2 × 4.5 Ų and 3.8 × 3.8 Ų.
2) SEM tests were not mentioned in the provided documents.
3) Gas sorption isotherms revealed that UTSA-280 adsorbs a large amount of C2H4 (2.5 mmol/g at 298 K and 1 bar) while showing negligible adsorption of C2H6 (0.098 mmol/g).
3. Application:
UTSA-280 was tested for the separation of C2H4/C2H6 mixtures. The material demonstrated high ethylene productivity (1.86 mol/kg) and complete exclusion of ethane, achieving >99% purity of ethylene in the final product.
4. Mechanism:
Single-crystal X-ray diffraction and DFT calculations revealed that C2H4 molecules fit into the rigid channels through weak C–H···O and π···π interactions, while C2H6 is excluded due to its larger cross-sectional area. The framework maintains its rigidity during the adsorption process, ensuring selective molecular sieving.
Outlook:
This research achieved significant progress in the selective separation of ethylene from ethane using a rigid MOF with precisely defined channels. The findings highlight the potential of UTSA-280 for industrial C2H4/C2H6 separation, offering energy-efficient and environmentally friendly alternatives to conventional distillation processes.
Molecular sieving of ethylene from ethane using a rigid metal–organic framework
Authors: Rui-Biao Lin, Libo Li, Hao-Long Zhou, Hui Wu, Chaohui He, Shun Li, Rajamani Krishna, Jinping Li, Wei Zhou, Banglin Chen
DOI: 10.1038/s41563-018-0206-2
Link: https://www.nature.com/articles/s41563-018-0206-2
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