Efficient Mechanochemical Synthesis of MOF-5 for Linear Alkanes Adsorption

An efficient mechanochemical method was proposed to synthesize MOF-5 with high BET area within minutes. The effects of parameters such as solvents activation, the metal/ligand ratio, grinding speed and time were carefully studied and the optimized MOF-5-B was used to investigate its adsorption properties of linear alkanes (C1–nC7). The results showed that solvents activation played an important role in the formation of MOF-5. Besides, the Zn2+/BDC ratio had a great impact on the formation of crystalline MOF-5, and the appropriate Zn2+/BDC ratio was 3:1 for mechanochemical synthesis of MOF-5. Grinding for 60 min could lead to a better crystallinity and the highest surface area of MOF-5-B. The resulting MOF-5-B possessed BET area of 3465.9 m2·g–1. More importantly, MOF-5-B showed a preferential adsorption for long alkanes over short alkanes at low pressures. The saturated adsorption capacities of nC4–nC7 decreased with the increase of hydrocarbon chain length. The isosteric heats of C1–nC7 increased with the increase of the alkyl chain length. Furthermore, the adsorption capacities of the alkanes (C3–nC7) on MOF-5-B were much higher than those of conventional activated carbons and zeolites.