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% (Mn@Nb-Y30). 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 MOx@Nb-zeolite 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.

Automated summary

The oxidation of 5-hydroxymethylfurfural (HMF) to 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) has been studied using MOx@Nb-zeolite catalytic systems. The catalysts have hierarchical texture and acid-base properties, and were characterized using various techniques. A synergistic effect between MOx and Nb species was identified, which facilitated the activation of t-BuOOH and the oxidation of HMF. The absence of FDCA in the reaction products can be attributed to the presence of acidic sites that prevent further oxidation of HMFCA.