Mono- and bimetallic catalysts for glucose oxidation

Mono- and bimetallic catalysts (Au, Pt, Pd and Rh) in form of supported particles or colloidal dispersions were tested in the aerobic oxidation of d-glucose to d-gluconic acid in water solution under mild conditions. Whereas the activity of single metals under acidic conditions was weak in the case of Au and Pt (TOF = 51–60 h−1) and very low in the case of Rh and Pd (TOF < 2), the activity of the bimetallic particles resulted enhanced by combining Au with Pd and Pt. In the latter case high TOFs (max 924 h−1) allow a new route to the synthesis of gluconic acid.In the presence of alkali at pH 9.5, the oxidation of glucose to gluconate resulted remarkably improved either in the case of monometallic gold or bimetallic catalysts, but no evident synergetic effects among metals have been detected.

Mono- and bimetallic gold catalysts, derived from nanometric colloidal sols, have been applied to the aerobic oxidation of d-glucose to d-gluconic acid under mild conditions (pressure 300 kPa, temperature 323–363 K). A synergetic effect was discovered adding palladium and, mainly, platinum to gold: in the case of Au:Pt = 2 w/w composition, the total conversion of glucose was obtained with TOF up to 924 h−1 (Fig. 1). The catalytic activity is increased more than one order of magnitude by working in the presence of alkali at pH 9.5, where monometallic Au is superior to Pd and Pt metals but no synergetic effects were detected after alloying with Pd and Pt. Figure optionsDownload as PowerPoint slide