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.