Selective oxidation of glucose to produce mono- and di-carboxylic acids is an attractive catalytic technology for the production of valuable chemical intermediates from biomass. Currently, most heterogeneously-catalyzed processes for the transformation of glucose to gluconic acid require the use of corrosive basic promoters (e.g. NaOH) to regulate the pH of the reaction, given that severe catalyst deactivation occurs once the solution enters the acidic regime. The development of a catalyst that maintains high catalytic activity and product selectivity in the absence of basic promoters is of considerable importance.  Here, we show that gold supported on nanocrystalline metal oxides quantitatively oxidize glucose to gluconic acid without the need to control pH. The catalysts exhibit high stability, maintaining activity after multiple cycles without excessive metal leaching.  Importantly, we shown that these materials maintain catalytic activity even under highly acidic conditions (pH >1.6) without jeopardizing the selectivity. This class of highly efficient, acid tolerant, and recyclable heterogeneous catalysts open greener routes for the oxidation of carbohydrates, while also presenting exciting opportunities to streamline biomass conversion schemes by coupling oxidation chemistry with acid-catalyzed processes.

Gold supported on nanocrystalline metal oxides as highly effective catalysts for the oxidation of glucose under base-free conditions

243rd National Meeting (2012)

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