Modification of Salt-Templated Carbon Surface Chemistry for Efficient Oxidation of Glucose with Supported Gold Catalysts

摘要

Gold nanoparticles dispersed on high-surface-area carbon materials were investigated as heterogeneous catalysts for the selective oxidation of D-glucose to D-gluconic acid in aqueous solution with molecular oxygen. Salt-templated porous carbon supports were obtained from different precursors with and without nitrogen and treated under air or hydrogen atmosphere to functionalize the surface with nitrogen, oxygen, or hydrogen. The influence of the surface atomic structure of the carbonaceous supports with similar pore structure on the size and catalytic properties of the metallic nanoparticles was studied at gold nanoparticle loadings of 0.4-0.7wt%. The functionalisation significantly influences the surface polarity of the support materials and the strength of the interaction with the gold nanoparticles. The surface polarity influences the structure and properties of the catalysts because both the gold deposition and the glucose oxidation reaction take place in the aqueous phase. Rather hydrophilic supports are obtained by doping with oxygen and nitrogen and lead to large gold nanoparticles with low catalytic activity. In contrast, the rather hydrophobic as-made and hydrogen-treated supports provide higher catalytic activity (metal time yield up to 1.5mol(Glucose)mol(Au)(-1)s(-1)) resulting from their smaller gold particles of 3-5nm in diameter.