De-Linker-Enabled Exceptional Volumetric Acetylene Storage Capacity and Benchmark C2H2/C2H4 and C2H2/CO2 Separations in Metal-Organic Frameworks.

Abstract

An ideal adsorbent for separation requires optimizing both storage capacity and selectivity, but maximizing both or achieving a desired balance remain challenging. Herein, a de-linker strategy is proposed to address this issue for metal-organic frameworks (MOFs). Broadly speaking, the de-linker idea targets a class of materials that may be viewed as being intermediate between zeolites and MOFs. Its feasibility is shown here by a series of ultra-microporous MOFs (SNNU-98-M, M = Mn, Co, Ni, Zn). SNNU-98 exhibit high volumetric C2H2 uptake capacity under low and ambient pressures (175.3 cm3 cm-3 @ 0.1 bar, 222.9 cm3 cm-3 @ 1 bar, 298 K), as well as extraordinary selectivity (2405.7 for C2H2/C2H4, 22.7 for C2H2/CO2). Remarkably, SNNU-98-Mn can efficiently separate C2H2 from C2H2/CO2 and C2H2/C2H4 mixtures with a benchmark C2H2/C2H4 (1/99) breakthrough time of 2325 min g-1, and produce 99.9999% C2H4 with a productivity up to 64.6 mmol g-1, surpassing values of reported MOF adsorbents.