Hierarchically MOx@Nb-zeolites for the selective oxidation of HMF to HMFCA

The oxidation of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) has been investigated on MOx@Nb-zeolite catalytic systems (where MOx = CoOx, MnOx or FeOx and zeolite - USY and Beta) with hierarchical texture and acid-base properties. These catalysts were exhaustively characterized by several techniques such as XRD, adsorption-desorption of liquid nitrogen at 77 K, CO2- and NH3-TPD, DRIFT, XPS, and SS NMR. The new hierarchically catalysts produced HMFCA with a selectivity of 97.0% for a XHMF = 95.0% ([email protected]). A synergetic effect between MOx and Nb species in the activation of t-BuOOH and oxidation of HMF has been identified. The absence of FDCA in the reaction products using [email protected] catalysts can be due to the preponderant presence of the acidic sites (associated to both framework and extra framework AlOx) which prevent a further oxidation of HMFCA to FDCA.