Selective oxidation of glucose to gluconic acid over Pd–Te supported catalysts

The effect of tellurium introduction on the activity and selectivity of home-made supported palladium catalysts in the oxidation of glucose to gluconic acid was studied. Bimetallic Pd–Te/SiO2 and Pd–Te/Al2O3 catalysts containing 5 wt.% of Pd and 0.3–5 wt.% of Te are characterized by both high activity and high selectivity to gluconic acid. However, catalysts 5%Pd–8%Te/support show lower conversion but their selectivity to gluconic acid is still high. The activation of bimetallic Pd–Te/support catalysts at 300 °C in hydrogen atmosphere leads to the formation of PdTe and PdTe2 compounds. The presence of intermetallic phase PdxTey on the surface of studied catalysts probably modifies their catalytic properties. The catalysts, for which the existence of PdTe was proved, show high activity and selectivity in the studied reaction. The existence of those compounds on the surface was confirmed by XRD, SIMS-ToF, XPS and TPR techniques. Moreover, another important feature of the bimetallic Pd–Te/support catalysts is their high stability in the process of glucose oxidation in the liquid phase.

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► Pd–Te/support catalysts show high activity and selectivity in the glucose oxidation.
► After catalyst activation in H2 the formation of PdTe and PdTe2 phases was observed.
► The best activities show the systems for which the presence of only PdTe phase was proved
► Intermetallic PdxTey compounds can modify the catalytic properties of studied systems.
► 5%Pd–1%Te/SiO2 system is characterized by high stability in the glucose oxidation.