Flow Semi-continuous Mechanochemistry as a Versatile and Efficient Tool for the Synthesis of Hydrocalumite and the Isomerization of Glucose to Fructose

Abstract

In this work, hydrocalumite, a layered double hydroxide with formula Ca2Al(OH)6Cl·2H2O, has been prepared for the first time using flow semi-continuous mechanochemistry with a DYNO®-MILL ESEARCH LAB (Willy A. Bachofen AG, Switzerland), with stoichiometric amount of reactants in water, after only 5 min at 25 °C. Hydrocalumite, before and after thermal treatment, was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG–DTA) and N2 sorption at − 196 °C. Moreover, calcined hydrocalumite has been evaluated as catalyst for the isomerization of glucose to fructose, a catalytic process which has also been performed in the same flow semicontinuous mechanochemical reactor. This mechanochemical system, unlike conventional ball milling, allows working in semi-continuous and/or continuous mode, using solvents and allowing heating control up to temperatures of 80 °C. The isomerization of glucose to fructose was successfully carried out in this reactor, demonstrating that hydrocalumite prepared by mechanochemistry is more active than that prepared by co-precipitation.