An alloy phase of Pd3Pb and the activity of Pb/Pd/C catalysts in the liquid-phase oxidation of sodium lactate to pyruvate

Catalytic Conversion of Lignocellulosic Biomass to Value-Added Organic Acids in Aqueous Media

“…for the oxidation of alcohols into aldehydes and carboxylic acids with oxygen in liquid solutions. This effect has been wildly investigated in the oxidation of glucose or other monosaccharides [1,52,67].…”

Enhancement of Catalytic Activity on Pd/C and Te–Pd/C During the Oxidative Dehydrogenation of Sodium Lactate to Pyruvate in an Aqueous Phase Under Pressurized Oxygen

“…This indicates that the oxidative dehydrogenation of the a-position of the hydroxyl group proceeds on Pt/C loaded with Pb but not on Pt/C only, and that a variety of catalyst modification similar to Pb/Pt/C have been reported in the selective hydrogenation of acetylene to olefins (Pb/Pd/CaCO 3 ; Lindlar catalyst [18] and Pb/Pd/SiO 2 [19]), diacetoxylation of 1,3-butadiene (Te/Pd/ C) [20] and reforming (PtTe and PtSb/Al 2 O 3 ) [21]. In the oxidative dehydrogenation of lactic acid to pyruvic acid under a constant pH of 8, it was similarly reported that Pd/C and Te/Pd/C were inactive and active, respectively, while Te/Pd/C showed complete deactivation at a specific atomic ration of Te/Pd = 0.3 in the catalyst [10][11][12]. It should be noted that these results were observed under atmospheric conditions.…”

“…By contrast, such successive reactions can be suppressed in liquid phase conversion due to the lower reaction temperature. Hayashi et al have developed catalytic conversions of lactic acid to pyruvic acid in an aqueous phase [10][11][12] coupled with ethyl lactate in an organic solution [13]. In the former conversion, they found no absorption of oxygen in the attempted oxidative dehydrogenation of lactic acid to pyruvic acid on Pd/C while a spectacular change in the oxidation activity in favor of pyruvic acid was observed in the presence of Pd/C that had been doped by either lead, bismuth or tellurium at 363 K [10][11][12].…”

“…Hayashi et al have developed catalytic conversions of lactic acid to pyruvic acid in an aqueous phase [10][11][12] coupled with ethyl lactate in an organic solution [13]. In the former conversion, they found no absorption of oxygen in the attempted oxidative dehydrogenation of lactic acid to pyruvic acid on Pd/C while a spectacular change in the oxidation activity in favor of pyruvic acid was observed in the presence of Pd/C that had been doped by either lead, bismuth or tellurium at 363 K [10][11][12]. It is noted that the solution pH should be adjusted at 8 by the use of considerable amount of NaOH solution [10][11][12], which suggests that sodium lactate instead of lactic acid is a possibility for the a raw material.…”

“…In the former conversion, they found no absorption of oxygen in the attempted oxidative dehydrogenation of lactic acid to pyruvic acid on Pd/C while a spectacular change in the oxidation activity in favor of pyruvic acid was observed in the presence of Pd/C that had been doped by either lead, bismuth or tellurium at 363 K [10][11][12]. It is noted that the solution pH should be adjusted at 8 by the use of considerable amount of NaOH solution [10][11][12], which suggests that sodium lactate instead of lactic acid is a possibility for the a raw material. Since the solution pH during the oxidative dehydrogenation of lactic acid must be adjusted for an increase in activity, the employment of an autoclave to press the reaction solution by oxygen is problematic due to concerns about the structure of a typical autoclave.…”