Adsorption of hydrogen sulfide by amine-functionalized metal organic framework (MOF-199): An experimental and simulation study

A series of amine modified MOF-199 adsorbents were prepared by impregnation method for using H2S room temperature removal. The parent and functionalized materials were characterized by XRD, FT-IR, SEM, N2 adsorption/desorption isotherms, and XPS. It was indicated that the structure of MOF-199 can be maintained after modification by appropriate tertiary amine triethanolamine (TEA), while primary amine monoethanolamine (MEA) and secondary amine diethanolamine (DEA) modification can destroy its structure due to the strong interaction with MOF-199. Breakthrough results showed that MOF-199 functionalized by TEA presented an improved H2S adsorption capacity of 2.74 mmol/g, higher than that of parent MOF-199 (1.67 mmol/g). Whereas, grafting of MEA and DEA into MOF-199 led to the sulfur capacity decrease to 0.83 mmol/g and 0.58 mmol/g, respectively. Calculation by density functional theory revealed that the binding energies of H2S adsorption on the TEA/MOF-199 were larger than that on bare MOF-199, which was considered to contribute to the improved adsorption. The enhanced binding energy of H2S on the TEA/MOF-199 was attributed to the hydroxyl in TEA.