Modified Niobium Oxyhydroxide Catalyst: An Acetalization Reaction to Produce Bio‐additives for Sustainable Use of Waste Glycerol

We report the synthesis and characterization of new niobium oxyhydroxide catalysts from ammonium niobium oxalate (NH4[NbO(C2O4)(2)(H2O)](H2O)(n)) or niobium chloride (NbCl5) precursors. The materials have been modified by incorporating a surfactant, specifically cetyltrimethylammonium bromide, on the catalyst surface to impart partial hydrophobicity to the catalyst. The change in the precursor during the synthesis changes properties associated with the morphology, texture and number of acid sites. These properties provide increased contact at the interface between the hydrophilic and hydrophobic regions to improve the catalytic properties, particularly in biphasic reactions. Acetalization reactions were tested using three different glycerols: commercial glycerol p.a., a crude residual originating from biodiesel production and the same material after desalination. The results show 65 and 60% conversion for the acetalization under mild reactions conditions.