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A metal–organic framework functionalized with piperazine exhibiting enhanced CH₄ storage

Zhang, Mingxing, Chen, Cong, Wang, Qian, Fu, Wensheng, Huang, Kunlin, Zhou, Wei
Journal of materials chemistry A 2016 v.5 no.1 pp. 349-354
ambient temperature, coordination polymers, lipophilicity, methane, piperazine, porosity, United States
NJU-Bai 19, the first cycloaliphatic ring (piperazine) functionalized MOF-505 analogue, exhibits a notably high methane storage capacity of 246.4 cm³ (STP) cm⁻³ (at room temperature and 65 bar); this is 93.6% of the new volumetric target of the US Department of Energy if the packing density loss is ignored. Compared with NOTT-101, when piperazine groups are inserted, the methane uptake capacity of NJU-Bai 19 at 65 bar and RT can be significantly enhanced with lower Qₛₜ. A relatively low increase was also observed in the uptake at 5 bar. Thus it has a much higher methane storage working capacity (deliverable amount of methane between 65 and 5 bar) of 185 cm³ (STP) cm⁻³ compared with NOTT-101 (174 cm³ (STP) cm⁻³). When the temperature was decreased from 298 to 273 K at working pressures between 65 bar and 5 bar, the volumetric CH₄ working capacity of NJU-Bai 19 is almost unchanged (from 185 to 189 cm³ (STP) cm⁻³), while some of the famous MOFs with high Qₛₜ showed a decrease with a decrease in temperature. The combination of the balanced porosity and framework density and the lipophilic surface is considered to result in the increased methane storage and working capacities.