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 CO2 separation performance of MIL‐53(Al). CO2, CH4, and N2 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 CO2/CH4 and CO2/N2 selectivities of the MOF. Of the composite materials that were tested, BMIM]PF6]/MIL‐53(Al) exhibited the largest increase in CO2/CH4 selectivity, 2.8‐times higher than that of pristine MIL‐53(Al), whilst BMIM]MeSO4]/MIL‐53(Al) exhibited the largest increase in CO2/N2 selectivity, 3.3‐times higher than that of pristine MIL‐53(Al). A comparison of the CO2 separation potentials of the IL/MOF composites showed that the BMIM]BF4]‐ and BMIM]PF6]‐incorporated MIL‐53(Al) composites both showed enhanced CO2/N2 and CO2/CH4 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. |