Gas adsorption in shaped zeolitic imidazolate framework-8

Zeolitic imidazolate framework-8 (ZIF-8) was prepared through a solve-thermal reaction method and then shaped using different additives. The influence of the shaping conditions on the microstructure of the shaped samples was characterized by the XRD, BET, and SEM techniques. The results demonstrate that the compressive strength of the various shaped tablets is greatly increased and capable of meeting the industrial requirements compared to the unshaped ZIF-8 and that the loss rate of specific surface areas was maintained at 10% after the addition of 10%(by mass) binder and 10%(by mass) solvent. The adsorption isotherms of CO2, CH4, C3H8, and C3H6 on powdery ZIF-8 and the shaped tablets (T-shaped ZIF-8, C-shaped ZIF-8, and N-shaped ZIF-8) were determined through volumetric measurements under different pressures and temperatures (298.2, 323.2, and 348.2 K). The adsorption capacities of the gases on both the ZIF-8 powder and the shaped tablets follow the order C3H6 > C3H8 > CO2 > CH4. Furthermore, the results show that the adsorption capacities of the gases on the shaped tablets are lower by approximately 10%–20% than those on the powdery ZIF-8. In fact, the adsorption equilibrium isotherms for CO2, CH4, C3H8, and C3H6 on both powdery and shaped ZIF-8 can be well described by the Langmuir equation.

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