A microporous water stable MOF for consistent and selective C2H2/C2H4 separation

Polymer-grade ethylene production requires the removal of trace acetylene, which possesses an intractable in-dustrial separation task. Metal-organic frameworks (MOFs) having stability in water/moisture-containing en-vironments are the promising alternative physisorbent material for the purification of C2H4 from C2H2- containing mixtures. In this study, a three-dimensional MOF (IITKGP-30) with narrow pore channels (-4.5 x 4.5 & ANGS;2) is developed for C2H2/C2H4 separation exhibiting excellent IAST separation selectivity of 3.3 (1:99) and 6.2 (50:50) at 295 K under 1 bar. Theoretical investigation revealed preferentially binding of acetylene molecules to the metal site in an end-on fashion equivalent to 4.76 kJ mol-1 more binding energy than ethylene. Dynamic breakthrough experiments with 1:99 (v/v) C2H2/C2H4 mixtures at 298 K revealed a complete separation of the binary mixture with excellent breakthrough selectivity of 2.4 and the ethylene productivity of 10.4 mL g-1. It is highly stable under 97% RH as long as 15 days and in the presence of water, can maintain a C2H2 uptake and retention time minimum up to three breakthrough cycles with ease of regenerability, thus showing its great promise for practical deployment.

Automated summary

A three-dimensional metal-organic framework (IITKGP-30) with narrow pore channels was developed for efficient separation of C2H2 from C2H4, exhibiting excellent separation selectivity and stability.