High Working Capacity Acetylene Storage at Ambient Temperature Enabled by a Switching Adsorbent Layered Material.

Unlike most gases, acetylene storage is a challenge because of its inherent pressure sensitivity. Herein, a square lattice (sql) coordination network [Cu(4,4'-bipyridine)2(BF4)2]n (sql-1-Cu-BF4) is investigated with respect to its C2H2 sorption behavior from 189 to 298 K. The C2H2 sorption studies revealed that sql-1-Cu-BF4 exhibits multistep isotherms that are temperature-dependent and consistent with the transformation from "closed" (nonporous) to four "open" (porous) phases induced by the C2H2 uptake. The Clausius-Clapeyron equation was used to calculate the performance of sql-1-Cu-BF4 for C2H2 storage at pressures >1 bar, which revealed that its volumetric working capacity at 288 K is slightly superior to acetone (174 vs 170 cm3 cm-3) over a safer pressure range (1-3.5 vs 1-15 bar). Molecular simulations provided insights into the observed switching phenomena, revealing that the layer expansion of sql-1-Cu-BF4 occurs via intercalation and inclusion of C2H2. These results indicate that switching adsorbent layered materials offer promise for utility in the context of C2H2 storage and delivery.