Highly Efficient Separation of CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub> from Natural Gas on a Novel Copper-Based Metal–Organic Framework
Danxia Lin, Shi Tu, Liang Yu, Yinuo Yuan, Ying Wu, Xin Zhou, Zhong Li, Qibin Xia
Abstract
The separation of light hydrocarbons like methane, ethane, and propane is an important section of the chemical industry. Herein, we reported a novel porous metal–organic framework (MOF) Cu-IPA and investigated its CH 4 /C 2 H 6 /C 3 H 8 separation performance, particularly for efficient capture of C 2 H 6 and C 3 H 8 at low concentrations. Cu-IPA featured 1D hexagonal channels and triangular channels decorated with extensive oxygen atoms. It showed high C 2 H 6 and C 3 H 8 capacities in the low-pressure region, where C 3 H 8 uptake at 5 kPa was 1.62 mmol/g and C 2 H 6 uptake reached 1.33 mmol/g at 10 kPa, suggesting the strong adsorption affinities toward C 2 H 6 and C 3 H 8 . For an equimolar C 2 H 6 /CH 4 mixture, Cu-IPA exhibited a considerable IAST selectivity of 40, exceeding most reported MOF adsorbents. Excellent CH 4 /C 2 H 6 /C 3 H 8 separation performance for Cu-IPA can be attributed to its appropriate pore size and abundant accessible oxygens atoms in the triangular channel. The molecular simulation revealed that Cu-IPA tended to form stronger C–H ··· O interactions with C 2 H 6 and C 3 H 8 due to the higher polarizabilities, resulting in larger interaction differences between C 2 H 6 /CH 4 and C 3 H 8 /CH 4 . Breakthrough tests also supported the excellent dynamic separation performance and recyclability of Cu-IPA.