Monometallic Au, Pt and Pd on carbon catalysts show poor activity in the liquid phase oxidation of D-sorbitol to gluconic/gulonic acids. However, by using bimetallic based catalysts (Au–Pt or Au–Pd) a great enhancement in the activity has been observed with respect to all the monometallic catalysts tested probably due to a synergetic effect between Au and Pt or Pd. In fact physical mixture of monometallic catalysts presented poor activity. Bimetallic showed a resistance to poisoning by dioxygen and by reaction products as high as gold monometallic catalyst, but also an improved selectivity toward monooxidation with respect to monometallic.
oxidation of polyols sorbitol oxidation bimetallic catalyst gold/palladium gold/platinum