Oxidation of glucose and gluconate on Pt, Pt Bi, and Pt Au catalysts

Abstract

SSDI 0 1 6 5 -0 5 1 3 ( 9 6 ) 0 0 0 0 6 -3 Abstract.Glucose and gluconate aqueous solutions (2 mol/l) were oxidized with air (atmospheric pressure, 333K, pH 7) on active charcoal-supported, platinum catalysts (catalytic ratios substrate/Pt 2 787); some catalysts were promoted with bismuth or gold. The activity of unpromoted Pt/C catalysts for glucose oxidation was comparable with that of Pd-Bi/C catalysts and there was no deactivation; gluconate formed transiently was oxidized into glucarate, the final selectivity did not exceed 50%. The oxidation of gluconate on very well dispersed Pt catalysts prepared by cationic exchange or anionic adsorption leads to higher glucarate selectivities than those previously reported, in spite of the fact that the present solutions were much more concentrated and reduced amounts of platinum were used. Addition of bismuth adatoms by surface redox reaction produces a shift in selectivity towards 2-ketogluconate. Addition of gold adatoms on platinum decreases the catalyst deactivation.

Gel-type ion exchange resin stabilized Pd-Bi nanoparticles for the glycerol oxidation in liquid phase

“…Another possible explanation of this phenomenon is a diffusion of metallic bismuth towards the external surface of the active phase by the reason of its lower surface energy compared to palladium [52]. In view of the same bulk composition of both compared catalysts which can provide the same environment for the diffusion through the material, the coverage of Pd by Bi in line with the literature results seems to be more likely in our case [30,31]. The results may explain the different spatial configuration of the metallic particles observed in the SEM pictures for both the compared catalysts (Figs.5E and F).…”

“…A second metal or promoter is added sometimes in order to improve the activity and/or selectivity, to inhibit the over-oxidation or to prevent the deactivation. Bismuth is one of the well-established promoters of supported Pd and Pt catalysts for the selective liquid phase oxidation of alcohols [30][31][32]. The promoter itself is inactive for the oxidation reactions, but when associated with the noble metal, it can considerably suppress the oxygen poisoning of the Pd surface [30], increase the reaction rate [33,34] and modify the selectivity [12,13,35].…”

“…Bismuth is one of the well-established promoters of supported Pd and Pt catalysts for the selective liquid phase oxidation of alcohols [30][31][32]. The promoter itself is inactive for the oxidation reactions, but when associated with the noble metal, it can considerably suppress the oxygen poisoning of the Pd surface [30], increase the reaction rate [33,34] and modify the selectivity [12,13,35]. Models proposed to interpret the role of promoters include the formation of i) a complexes between an α-functionalized alcohol, a surface Pt or Pd atom and a promoter [36], ii) a bifunctional catalysis [37], iii) an ordered alloy [34], iv) Bi may act as cocatalyst due to its higher affinity for oxygen and protect Pt or Pd from overoxidation [36] or v) as a homogeneous catalyst by leached promoter [31].…”

Mesoporous carbon-confined Au catalysts with superior activity for selective oxidation of glucose to gluconic acid

“…In particular, the oxidation of glucose to gluconic acid over noble metal catalysts, including Pt, Pd and Au, has been extensively studied. [2][3][4] Compared with Pd and Pt catalysts, supported Au catalysts have shown higher catalytic activity with excellent selectivity to gluconic acid as reported. [5][6][7] Rossi and his co-workers 5 attributed this high catalytic performance to the higher resistivity of Au catalyst to overoxidation and self-poisoning compared to Pt or Pd.…”

Process Options for the Catalytic Conversion of Renewables into Bioproducts

“…The trend is to develop heterogeneous processes where the catalysts are recycled many times or used in continuous reactor for a long time on stream. Hydrogenation of glucose to sorbitol [19] and oxidation of glucose to gluconic acid [20] are illustrative examples of very selective catalytic conversion (yield > 99%) where the catalysts are used many times with negligible loss of activity and selectivity.…”