Sci Rep. 2023 Aug 10;13(1):13012. doi: 10.1038/s41598-023-40191-9.
To improve the CO2/N2 separation performance of metal-organic frameworks (MOFs), amine functionalized deep eutectic solvents (DESs) (choline chloride/ethanolamine (DES1), choline chloride/ethanolamine/diethanolamine (DES2), and choline chloride/ethanolamine/methyldiethanolamine (DES3)) confined in the NH2-MIL-53(Al). NH2-MIL-53(Al) impregnated with DES was synthesized and characterized using N2-sorption analysis and Fourier transform infrared (FTIR) spectroscopy. Morphology of the synthesized MOFs was investigated using scanning electron microscopy (SEM). Also, elemental analysis was determined by energy-dispersive X-ray spectroscopy (EDX). CO2 adsorption isotherms of amine-functionalized DESs impregnated NH2-MIL-53(Al) were measured at temperatures range of 288.15-308.15 K and pressures up to 5 bar. The results reveal that the impregnated MOF with functional group of amine DES improves separation performance NH2-MIL-53(Al). CO2 adsorption capacity of DES1/NH2-MILS-53(Al) was twofold respect to of pristine NH2-MIL-53(Al) at 5 bar and 298.15 K; which helps to guide the logical design of new mixtures for gas separation applications. Also, the heat of adsorption for the synthesized NH2-MIL-53(Al) and DESs/NH2-MIL-53(Al) were estimated. Most importantly, CO2 chemisorption by NH2 group in the sorbent structure has a significant effect on the adsorption mechanism.