Understanding the Enhanced Separation Mechanism of C<sub>2</sub>H<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> at Low Pressure by HKUST−1
The production of ethylene (C<sub>2</sub>H<sub>4</sub>) is typically accompanied by the formation of impurities like ethane (C<sub>2</sub>H<sub>6</sub>), making the separation of C<sub>2</sub>H<sub>4</sub> and C<sub>2</...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-10-01
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| Series: | Chemistry |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2624-8549/6/6/77 |
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| Summary: | The production of ethylene (C<sub>2</sub>H<sub>4</sub>) is typically accompanied by the formation of impurities like ethane (C<sub>2</sub>H<sub>6</sub>), making the separation of C<sub>2</sub>H<sub>4</sub> and C<sub>2</sub>H<sub>6</sub> crucial in industrial processes. Here, we investigated the S-shaped adsorption phenomenon of C<sub>2</sub>H<sub>6</sub> on the metal–organic framework HKUST−1. The virial equation is used to fit the C<sub>2</sub>H<sub>6</sub> and C<sub>2</sub>H<sub>4</sub> adsorption isotherms under low coverage. The results showed that the repulsion energy between neighboring C<sub>2</sub>H<sub>6</sub> molecules was significantly higher than that between neighboring C<sub>2</sub>H<sub>4</sub> molecules, which was an important reason for the lower adsorption of C<sub>2</sub>H<sub>6</sub> by HKUST−1 at low coverage. As more molecules are adsorbed, gas molecules aggregate within pores, leading to more hydrogen bonds formed between HKUST−1 and larger-sized C<sub>2</sub>H<sub>6</sub> under high coverage conditions. This phenomenon plays a crucial role in the S-shaped adsorption behavior of HKUST−1 on C<sub>2</sub>H<sub>6</sub>. Additionally, this unique adsorption behavior allows for the efficient separation of C<sub>2</sub>H<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> mixtures at low pressures. The ideal adsorbed solution theory (IAST) selectivity of HKUST−1 for C<sub>2</sub>H<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> mixtures was 3.78 at 283 K and 1 bar, but increased significantly to 7.53 under low pressure. This unique mechanism provides a theoretical basis for the low-pressure separation of C<sub>2</sub>H<sub>4</sub>/C<sub>2</sub>H<sub>6</sub> by HKUST−1 and establishes a solid foundation for future practical research applications. |
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| ISSN: | 2624-8549 |