High pressure methane adsorption in the metal-organic frameworks Cu3(btc)2, Zn2(bdc)2dabco, and Cr3F(H2O)2O(bdc)3

摘要

Three porous coordination polymers Cu3(btc)2 (HKUST-1) (btc = benzene-1,3,5-tricarboxylate) (1), Zn2(bdc)2dabco (2) (bdc = benzene- 1,4-dicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane), and Cr3F(H2O)2O(bdc)3 (MIL-101) (3) were evaluated as methane storage materials. The compounds were synthesized using solvothermal method and identified as pure phases using powder X-ray diffraction. Nitrogen physisorption at 77 K revealed a high specific micropore volume ranging from 0.75 to 1.303 cm~3 g~(-1). Methane adsorption isotherms were measured using gravimetric method at 303 K up to 200 bar. A volumetric miniature tank system was used to measure the effective volumetric storage capacity taking the packing density into account. Among the three materials, Cu3(btc)2 shows the highest excess adsorption at 303 K (15.7 wt.%) and effective volumetric storage capacity of 228 m~(-3) m~(-3) (150 bar), whereas for Zn2(bdc)2dabco and MIL-101 the maximum excess adsorption is lower (14.3 and 14.2 wt.%, respectively). For MIL-101, the maximum in the excess adsorption is observed at higher pressure (125 bar) as compared to Cu3(btc)2 and Zn2(bdc)2dabco (75 bar).