Tailoring basic and acidic properties of MgAl hydrotalcite by fluoride anions: Effect on glycerol oligomerisation

In this work, two families of catalysts based on mixed metal oxides derived from MgAl hydrotalcites were synthesized with a Mg/Al molar ratio 3. On the one hand, in first family, fluoride anion was incorporated interlayer space by using ammonium fluoride, exploiting “memory effect” characteristic hydrotalcites. second anions substituted layer, incorporating directly them during precipitation hydroxides, cryolite as precursor for both fluorine and aluminium. The transformed into thermal treatment tested glycerol etherification reaction at 230 ºC, batch reactor atmospheric pressure. corresponding characterized different experimental techniques, such X-ray diffraction (XRD), elemental analysis (CHF), N2 sorption − 196 thermogravimetric (ATD-TG), photoelectron spectroscopy (XPS), temperature-programmed desorption CO2 NH3 (CO2-TPD NH3-DTP) solid state nuclear magnetic resonace (ssNMR) 19F. It found that prepared hydrotalcites, where synthesis step cryolite, achieved maximum conversion values complete selectivity towards diglycerol. Diglycerols unique detected products and, some cases, formation triglycerols also detected.