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.与绝大多数气体不同，乙炔的储存极具挑战，因其固有的压力敏感性。本文针对一种方格晶格（square lattice, sql）配位网络[Cu(4,4'-联吡啶)₂(BF₄)₂]ₙ（命名为sql-1-Cu-BF₄）展开研究，考察其在189至298 K温度范围内对乙炔（C₂H₂）的吸附行为。乙炔吸附研究结果表明，sql-1-Cu-BF₄呈现出与温度相关的多步吸附等温线，该等温线与乙炔吸附诱导下材料从"闭合"（无孔）相转变为四种"开放"（多孔）相的过程相符。采用克劳修斯-克拉佩龙方程计算了sql-1-Cu-BF₄在压力大于1 bar条件下的乙炔储存性能，结果显示，在更安全的压力区间（1~3.5 bar vs 1~15 bar）内，该材料在288 K下的体积工作容量略优于丙酮（174 vs 170 cm³·cm⁻³）。分子模拟为所观测到的开关现象提供了机理解释，结果表明sql-1-Cu-BF₄的层间扩张是通过乙炔的插层与包合作用实现的。上述研究结果表明，具备开关特性的层状吸附材料在乙炔储存与输送领域具有良好的应用前景。