Efficient ethylene purification by a robust ethane-trapping porous organic cage.

Su, Kongzhao; Wang, Wenjing; Du, Shunfu; Ji, Chunqing; Yuan, Daqiang · Nat Commun · 2021

basic_science · Level V

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Abstract

The removal of ethane (C<sub>2</sub>H<sub>6</sub>) from its analogous ethylene (C<sub>2</sub>H<sub>4</sub>) is of paramount importance in the petrochemical industry, but highly challenging due to their similar physicochemical properties. The use of emerging porous organic cage (POC) materials for C<sub>2</sub>H<sub>6</sub>/C<sub>2</sub>H<sub>4</sub> separation is still in its infancy. Here, we report the benchmark example of a truncated octahedral calix[4]resorcinarene-based POC adsorbent (CPOC-301), preferring to adsorb C<sub>2</sub>H<sub>6</sub> than C<sub>2</sub>H<sub>4</sub>, and thus can be used as a robust absorbent to directly separate high-purity C<sub>2</sub>H<sub>4</sub> from the C<sub>2</sub>H<sub>6</sub>/C<sub>2</sub>H<sub>4</sub> mixture. Molecular modelling studies suggest the exceptional C<sub>2</sub>H<sub>6</sub> selectivity is due to the suitable resorcin[4]arene cavities in CPOC-301, which form more multiple C-H···π hydrogen bonds with C<sub>2</sub>H<sub>6</sub> than with C<sub>2</sub>H<sub>4</sub> guests. This work provides a fresh avenue to utilize POC materials for highly selective separation of industrially important hydrocarbons.