Life Cycle Assessment of Solvothermal Zeolitic Imidazolate Framework-8 Synthesis: Is the Substitution of N,N-Dimethylformamide with Glycerol Carbonate Environmentally Sustainable?

In this work, a comparative life cycle assessment of the solvothermal synthesis of zeolitic imidazolate framework (ZIF-8) is reported.ZIF-8 is listed among the most representative structures of ZIFs, an emerging subclass of metal–organic frameworks (MOFs). ZIF-8 iscommonly synthesized through the solvothermal method, and the election solvents are currently N, N-dimethylformamide (DMF) andwater, both allowing the production of highly crystalline ZIF-8 with a high specific surface area. Considering the recently introducedsevere restrictions on the use of DMF as defined very recently by European Chemical Agency, an innovative synthetic procedure in thebiobased and nontoxic glycerol carbonate (GlyC) was reported. This approach delivers mesoporous ZIF-8 with high crystallinity andhigh specific surface area. The present study suggests a cradle-to-gate life cycle assessment of the laboratory scale ZIF-8 synthesis,comparing the same process in DMF and GlyC in terms of their environmental impacts. The results help to demonstrate that therespect of the 7th principle of green chemistry (using GlyC instead of DMF) does not necessarily embody, at present, a sustainable choice.