Bismuth as an additive modifying the selectivity of palladium catalysts

• Published in: Journal of molecular catalysis. A, Chemical Chemical, 2003-01, Vol.191 (1), p.87-92
• Main Authors: Karski, S, Witońska, I
• Format: Article
• Language: English
• Subjects: Catalysis; Catalytic oxidation of glucose; Catalytic reactions; Chemistry; Exact sciences and technology; General and physical chemistry; Pd–Bi catalysts; Silica; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(02)00359-X

This paper deals with the oxidation of glucose with palladium on SiO 2 catalysts modified with bismuth. The catalysts were characterized by XRD studies and temperature-programmed oxidation (TPO) method after their reduction at 533 K. The influence of bismuth addition on the activity and selectivity of palladium catalysts supported on SiO 2 in the reaction of glucose oxidation to gluconic acid was studied. The catalysts modified with Bi show much better selectivity and activity than palladium catalysts. The XRD studies proved the presence of intermetallic compounds BiPd and Bi 2Pd, which probably increase activity and selectivity of PdBi/SiO 2 catalysts in the oxidation of glucose. The TPO studies of catalysts containing 5 wt.% Pd/SiO 2, 3 wt.% Bi/SiO 2 and 5 wt.% Pd–5 wt.% Bi/SiO 2 show that palladium oxidation occurs at much higher temperatures than in the case of bismuth. The maximum rate of Pd oxidation occurs at around 580 K while the maximum rate of Bi oxidation takes place at around 430 K. Considering the above facts, a reaction involving bimetallic catalysts in oxidizing atmosphere at 333 K should not lead to surface oxidation of palladium and thus their deactivation.