Synthesis, Characterization, and Life Cycle Assessment of MIL-101(Cr) for Sorption Applications

MIL-101(Cr) is considered a potential material for sorption-based storage applications; however, the chemicals and protocols used in its synthesis pose several environmental issues. This situation demands establishing a green synthesis protocol using eco-friendly chemicals while fulfilling the end application needs. Based on the life cycle assessment (LCA) concept, the present study examines the role of different protocols (mechanochemical and solvothermal) and washing solvents (N,N-dimethylformamide [DMF] and dimethyl sulfoxide [DMSO]) in synthesizing the MIL-101(Cr) and their impact on the environment. Towards this, four samples were synthesized using the aforementioned protocols and washing solvents and tested for carbon dioxide (CO2) capture and thermochemical energy storage (TCES). At 25 degrees C and 1 bar, the CO2 uptake ranges from 1.4 to 2.33 mmol g-1. These samples also demonstrated their suitability for a typical TCES application, with reaction enthalpies ranging from 186 to 1170.2 J g-1. The LCA study suggests that the heating and drying processes contributed over 65% to the environmental impact, while the metal ion poses higher human carcinogenic toxicity and health risks. Replacing the DMF with DMSO helps reduce the impact on marine eutrophication by 91%. This comprehensive LCA study helped understand the role of the synthesis protocol and washing solvent in influencing the pore characteristics of MIL-101(Cr) and offers critical insights for sustainable MOF production.