Beijing University of Technology's MOF BUT-313 purifies C2F6 from fluorocarbon mixture to over 99.98%
Replacing one oxygen atom with sulfur in the linker narrowed the pore to 4.2 Å, so the framework adsorbs C2H2F4 and C2HF5 but largely excludes C2F6 in laboratory tests.
Researchers at the State Key Laboratory of Materials Low-Carbon Recycling, Beijing University of Technology, reported a metal-organic framework, BUT-313, for purifying hexafluoroethane (C2F6) from a ternary mixture with the hydrofluorocarbons C2H2F4 and C2HF5. The work was published in Nature Communications. According to the authors, conventional routes for this separation are energy-intensive. The material was tested at laboratory scale, including a batch scaled up to 10 g. doi.org
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Pore geometry change in the linker
The team started from the framework PCP-FDCA and made a minimal substitution of oxygen with sulfur in the dicarboxylate linker. According to the authors, this single-atom edit turns the original rectangular channel into an hourglass-like pore with a bottleneck constriction of 4.2 Å. doi.org
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The narrowed constriction acts as a shape-selective molecular sieve. BUT-313 strongly suppresses uptake of the more symmetric C2F6, while it still adsorbs the anisotropic fluorocarbons C2H2F4 and C2HF5. doi.org
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Adsorption and separation results
At 298 K and 100 kPa, BUT-313 shows uptake ratios of 7.7 for C2H2F4/C2F6 and 6.0 for C2HF5/C2F6. The authors describe these as the highest uptake ratios reported. The C2H2F4/C2F6 selectivity is 487.0, which the authors call a record-high value. doi.org
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In ternary mixture column experiments, BUT-313 delivered C2F6 with a purity above 99.98% and a productivity of 184.5 L/kg. The authors report that the performance was retained over multiple cycles and after scale-up to the 10 g level. doi.org
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The study was carried out by Heng-Yu Ruan, Xin Zhang, Zhi-Wei Zhai, Jia-Mei Yu, Xuefeng Bai and Jian-Rong Li. The results come from laboratory experiments with a framework material, not from an industrial installation. doi.org
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