Activity and selectivity of Pd–Bi/SiO2 catalysts in the light of mutual interaction between Pd and Bi

This work is devoted to the study of interactions between Pd and Bi in Pd–Bi/SiO2 catalysts and their connection with activity and selectivity of those systems in the selective oxidation of glucose and lactose.In the oxidation of glucose, high activity and selectivity of Pd–Bi/SiO2 systems having higher bismuth content were observed. For those systems the formation of BiPd and Bi2Pd took place.In the case of lactose oxidation better catalytic properties were found for Pd–Bi/SiO2 systems with a small amount of bismuth, where mainly a binary alloy BiPd is formed.

The presence of intermetallic compounds on the surface of 5% Pd–5% Bi/SiO2 catalysts are confirmed by ToF-SIMS measurements. The studies reveal lack of homogeneity of the sample. Palladium and bismuth are found in distinct clusters on the studied area, and so they are not evenly dispersed on the carrier. The concentration of palladium and bismuth is the highest on the same areas of the studied sample. Moreover, in the spectrum of secondary ions maxima of signal intensity for the following mass: 314, 315 and 317 ascribed to intermetallic compound BiPd were found. Figure optionsDownload as PowerPoint slide