<p>Zirconium based Metal-Organic Framework
UiO-66 is to date considered one of the benchmark compound among stable MOFs
and it has attracted a huge attention for its employment in many strategic
applications. Large scale production of UiO-66 for industrial purposes requires
the use of safe and green solvents, fulfilling the green chemistry principles
and able to replace the use of <i>N,N</i>-Dimethyl-Formamide (DMF), which,
despite its toxicity, is still considered the most efficient solvent for
obtaining UiO-66 of high quality. Herein we report on a survey of about 40
different solvents with different polarity, boiling point and acidity, used for
the laboratory scale synthesis of high quality UiO-66 crystals. The solvents
were chosen according the European REACH
Regulation 1907/2006 among those having low cost, low
toxicity and fully biodegradable. Concerning MOF synthesis, the relevant
parameters chosen for establishing the quality of the results obtained are the
degree are the crystallinity, microporosity and specific surface area,
yield and solvent recyclability. Taking into account also the chemical physical
properties of all the solvents, a color code was assigned in order to give a
final green assessment for the UiO-66 synthesis. Defectivity of the obtained products, the use
of acidic modulators and the use of alternative Zr-salts have been also taken
into consideration. Preliminary
results lead to conclude that GVL (γ-valerolactone) is among the most promising
solvents for replacing DMF in UiO-66 MOF synthesis. </p>
Extensive Screening of Green Solvents for Safe and Sustainable UiO-66 Synthesis
