Simultaneous removal of C 2 H 2 and C 2 H 6 for C 2 H 4 purification by robust MOFs featuring a high density of heteroatoms

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 11; no. 39; pp. 21401 - 21410
• Main Authors: Xian, Shikai, Peng, Junjie, Pandey, Haardik, Graham, Wells, Yu, Liang, Wang, Hao, Tan, Kui, Thonhauser, Timo, Li, Jing
• Format: Journal Article
• Language: English
• Published: United Kingdom Royal Society of Chemistry (RSC) 10.10.2023
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/D3TA01598J

Simultaneous removal of C 2 H 6 and C 2 H 2 from C 2 H 4 streams is of great importance in the petrochemical industry but remains a challenging task. To address this challenge, we have selected three isoreticular MOFs with high stability, low cost, and desirable scale-up ability, namely, MOF-303, MIL-160, and CAU-23 and assessed their potential in simultaneous removal of acetylene and ethane for ethylene purification. Each MOF exhibits desirable C 2 H 2 and C 2 H 6 uptake capacity (>5.5 mmol g −1 and >4 mmol g −1 , respectively), as well as good C 2 H 2 /C 2 H 4 selectivity (>2) and C 2 H 6 /C 2 H 4 selectivity (>1.5). Notably, MOF-303 takes up 4.96 mmol g −1 C 2 H 6 at 298 K and 1 bar, the highest value among the three MOFs, with C 2 H 6 /C 2 H 4 selectivity in the range of 1.55–2.47. MIL-160 possesses a very high C 2 H 2 uptake (9.1 mmol g −1 ) and C 2 H 2 /C 2 H 4 selectivity, 10.6 (1 : 1, v/v), at 298 K, much higher than those of all other MOFs tested to date for simultaneous removal of C 2 H 6 and C 2 H 2 from C 2 H 4 . The results from breakthrough experiments confirm that all three MOFs demonstrate excellent performance for C 2 H 4 purification in a ternary mixture of C 2 H 6 /C 2 H 4 /C 2 H 2 (1 : 1 : 1, v/v/v). For MOF-303, MIL-160, and CAU-23, polymer-grade C 2 H 4 up to 0.164, 0.21, and 0.181 mmol g −1 can be obtained from the equimolar ternary mixture in a single separation step from the breakthrough experiment. Additionally, DFT calculations have been performed to further investigate the mechanism of adsorption/separation for C 2 H 6 , C 2 H 4 , and C 2 H 2 .