Search for: All records

Pyrazine‐linked hybrid ultramicroporous (pore size <7 Å) materials (HUMs) offer benchmark performance for trace carbon capture thanks to strong selectivity for CO₂over small gas molecules, including light hydrocarbons. That the prototypal pyrazine‐linked HUMs are amenable to crystal engineering has enabled second generation HUMs to supersede the performance of the parent HUM,SIFSIX‐3‐Zn, mainly through substitution of the metal and/or the inorganic pillar. Herein, we report that two isostructural aminopyrazine‐linked HUMs,MFSIX‐17‐Ni(17=aminopyrazine; M=Si, Ti), which we had anticipated would offer even stronger affinity for CO₂than their pyrazine analogs, unexpectedly exhibit reduced CO₂affinity but enhanced C₂H₂affinity.MFSIX‐17‐Niare consequently the first physisorbents that enable single‐step production of polymer‐grade ethylene (>99.95 % forSIFSIX‐17‐Ni) from a ternary equimolar mixture of ethylene, acetylene and CO₂thanks to coadsorption of the latter two gases. We attribute this performance to the very different binding sites inMFSIX‐17‐NiversusSIFSIX‐3‐Zn.

Pyrazine‐linked hybrid ultramicroporous (pore size <7 Å) materials (HUMs) offer benchmark performance for trace carbon capture thanks to strong selectivity for CO₂over small gas molecules, including light hydrocarbons. That the prototypal pyrazine‐linked HUMs are amenable to crystal engineering has enabled second generation HUMs to supersede the performance of the parent HUM,SIFSIX‐3‐Zn, mainly through substitution of the metal and/or the inorganic pillar. Herein, we report that two isostructural aminopyrazine‐linked HUMs,MFSIX‐17‐Ni(17=aminopyrazine; M=Si, Ti), which we had anticipated would offer even stronger affinity for CO₂than their pyrazine analogs, unexpectedly exhibit reduced CO₂affinity but enhanced C₂H₂affinity.MFSIX‐17‐Niare consequently the first physisorbents that enable single‐step production of polymer‐grade ethylene (>99.95 % forSIFSIX‐17‐Ni) from a ternary equimolar mixture of ethylene, acetylene and CO₂thanks to coadsorption of the latter two gases. We attribute this performance to the very different binding sites inMFSIX‐17‐NiversusSIFSIX‐3‐Zn.

Porous materials capable of selectively capturing CO₂from flue‐gases or natural gas are of interest in terms of rising atmospheric CO₂levels and methane purification. Size‐exclusive sieving of CO₂over CH₄and N₂has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore‐size in a coordination network, [Cu(quinoline‐5‐carboxyate)₂]_n(Qc‐5‐Cu) ena+bles ultra‐high selectivity for CO₂over N₂(S_CN≈40 000) and CH₄(S_CM≈3300).Qc‐5‐Cu‐sql‐β, a narrow pore polymorph of the square lattice (sql) coordination networkQc‐5‐Cu‐sql‐α,adsorbs CO₂while excluding both CH₄and N₂. Experimental measurements and molecular modeling validate and explain the performance.Qc‐5‐Cu‐sql‐βis stable to moisture and its separation performance is unaffected by humidity.