Abstract
Five different imidazolium-based ionic liquids (ILs) were incorporated into a metal-organic framework (MOF), MIL-53(Al), to investigate the effect of IL incorporation on the CO(2) separation performance of MIL-53(Al). CO(2) , CH(4) , and N(2) adsorption isotherms of the IL/MIL-53(Al) composites and pristine MIL-53(Al) were measured to evaluate the effect of the ILs on the CO(2) /CH(4) and CO(2) /N(2) selectivities of the MOF. Of the composite materials that were tested, [BMIM][PF(6) ]/MIL-53(Al) exhibited the largest increase in CO(2) /CH(4) selectivity, 2.8-times higher than that of pristine MIL-53(Al), whilst [BMIM][MeSO(4) ]/MIL-53(Al) exhibited the largest increase in CO(2) /N(2) selectivity, 3.3-times higher than that of pristine MIL-53(Al). A comparison of the CO(2) separation potentials of the IL/MOF composites showed that the [BMIM][BF(4) ]- and [BMIM][PF(6) ]-incorporated MIL-53(Al) composites both showed enhanced CO(2) /N(2) and CO(2) /CH(4) selectivities at pressures of 1-5 bar compared to composites of CuBTC and ZIF-8 with the same ILs. These results demonstrate that MIL-53(Al) is a versatile platform for IL/MOF composites and could help to guide the rational design of new composites for target gas-separation applications.