Probing sub-5 Ångstrom micropores in carbon for precise light olefin/paraffin separation.
basic_science · Level V
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- Record sourced from PubMed, PMID 36864084.
- Also identified by DOI 10.1038/s41467-023-36890-6 and PMC identifier 9981619.
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Abstract
Olefin/paraffin separation is an important but challenging and energy-intensive process in petrochemical industry. The realization of carbons with size-exclusion capability is highly desirable but rarely reported. Herein, we report polydopamine-derived carbons (PDA-Cx, where x refers to the pyrolysis temperature) with tailorable sub-5 Å micropore orifices together with larger microvoids by one-step pyrolysis. The sub-5 Å micropore orifices centered at 4.1-4.3 Å in PDA-C800 and 3.7-4.0 Å in PDA-C900 allow the entry of olefins while entirely excluding their paraffin counterparts, performing a precise cut-off to discriminate olefin/paraffin with sub-angstrom discrepancy. The larger voids enable high C<sub>2</sub>H<sub>4</sub> and C<sub>3</sub>H<sub>6</sub> capacities of 2.25 and 1.98 mmol g<sup>-1</sup> under ambient conditions, respectively. Breakthrough experiments confirm that a one-step adsorption-desorption process can obtain high-purity olefins. Inelastic neutron scattering further reveals the host-guest interaction of adsorbed C<sub>2</sub>H<sub>4</sub> and C<sub>3</sub>H<sub>6</sub> molecules in PDA-Cx. This study opens an avenue to exploit the sub-5 Å micropores in carbon and their desirable size-exclusion effect.