Extraordinary Separation of Acetylene-Containing Mixtures in a Honeycomb Calcium-Based MOF with Multiple Active Sites.

Acetylene (CH) separation from multicomponent mixtures is vitally important but industrially challenging for the collection of high-purity CH. To address this requirement, the reaction between the alkaline-earth Ca ions with a dicarboxylate-diazolate linker, 4,6-di(1-tetrazol-5-yl)isophthalic acid (Hdtzip), gave rise to a new metal-organic framework (MOF) material [Ca(dtzip)HO]·2HO (). The material presents unique regular tubular channels based on threefolded helical rod-like secondary building units with rich open metal sites and exposed organic hydrogen-bonding N/O acceptors that enhance the interactions with CH molecules, endowing significant selectivity for CH over CH (5.4), CH (5.6), CH (30.0), and CO (7.7) at 298 K and 100 kPa. Column breakthrough experiments confirmed the extraordinary CH separation performance of the material with the separation time intervals in the range of 18-24 min g for binary (CH-CH, CH-CH, CH-CO, and CH-CH) or ternary (CH-CH-CH and CH-CH-CO) gas mixtures under dynamic conditions.