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 is commonly synthesized through the solvothermal method, and the election solvents are currently N, N-dimethylformamide (DMF) and water, both allowing the production of highly crystalline ZIF-8 with a high specific surface area. Considering the recently introduced severe restrictions on the use of DMF as defined very recently by European Chemical Agency, an innovative synthetic procedure in the biobased and nontoxic glycerol carbonate (GlyC) was reported. This approach delivers mesoporous ZIF-8 with high crystallinity and high 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 the respect of the 7th principle of green chemistry (using GlyC instead of DMF) does not necessarily embody, at present, a sustainable choice.