Platinum glycerol oxidation

Dihydroxyacetone (DHA), the oxidation product of the secondary hydroxy group of glycerol, is an artificial tanning agent in cosmetics and a pharmaceutical intermediate. Glycerol oxidation in acidic medium on a platinum-bismuth catalyst (Bi/ Pt atomic ratio = 3) prepared by coprecipitation of Pt and Bi salts, yielded 20 % DHA at 30 % conversion [70]. The deposition of bismuth on platinum particles by oxido-reduction (Bi/Pt = 0.13) yielded 37 % DHA at 70% conversion... 

Pd [83] Reduction by NaBH4 Vulcan 0.45 V vs. NHE The platinum-free Pdo.gBio.i/C exhibits similar activity towards glycerol oxidation as Pt/C... 

Selective catal3ftic oxidation with air of glycerol and oxygenated derivatives on platinum metals... 

The electrochemical oxidation of polyhydric alcohols, viz. ethylene glycol, glycerol, meso-erythritol, xilitol, on a platinum electrode show high reactivity in alkaline solutions of KOH and K2C03 [53]. This electro-oxidation shows structural effects, Pt(lll) being the most active orientation. This results from different adsorption interactions of glycerol with the crystal planes [59]. 

Kimura H, Tsuto K, Wakisaka T, Kazumi Y, Inaya Y. Selective oxidation of glycerol on a platinum-bismuth catalyst. Appl Catal A Gen. 1993 96 217-28. 

Garcia R, Besson M, Gallezot P. Chemoselective catalytic oxidation of glycerol with air on platinum metals. Appl Catal A Gen. 1995 127 165-76. 

Worz N, Brandner A, Claus P. Platinum-bismuth catalyzed oxidation of glycerol kinetics and the origin of selective deactivation. J Phys Chem C. 2010 114 1164-72. 

In summary, this work demonstrates that high selectivities for oxygenated keto-acids derived from glycerol may be obtained by catalytic oxidation on bismuth-promoted platinum under acidic conditions. However, problems of catalyst deactivation by adsorbed acids, overoxidation of targeted products and leaching of the promoter need to be overcome to attain the ultimate goal of theoretical yield. 

It was found as early as the middle of the 19th century that oxidation of alcohols to aldehydes and acids with molecular oxygen is catalyzed by platinum metals, but these reactions have been comparatively little studied. After the pioneering work of Heyns et al. [1,2] most of the reports in the open literature were published by a small number of research groups at Eindhoven [3-24], Delft [25-39], Zurich [40-56], and Villeurbanne [57-68], and the oxidation of glycerol and derivatives was studied by Kimura [69-74]. A few review papers were devoted to the liquid-phase oxidation of alcohols and carbohydrates on metal catalysts [31,48, 75-77]. 

E.C. Venancio, W.T. Nappom, and A. Motheo, Electro-oxidation of glycerol on platinum dispersed in polyaniline matrices, Electrochim. Acta, 47, 1495-1501 (2002). 

Platinum and palladium are effective catalysts for alcohol oxidation when used alone however, significant stability and selectivity improvements have been observed on incorporation of a second (usually less active) metal promoter such as Bi, Pb, and Sn [63-65]. These observations are common to aerobic selox of allyhc and benzylic alcohols, as well as polyols such as propylene glycol [64] and glycerol [66]. In the case of Bi, in situ X-ray absorption spectroscopy (XAS) and attenuated total reflection infrared spectroscopy (ATR-IR) indicate that the promoter protects Pt against deactivation by overoxidation and prevents site blocking by, for example, aromatic solvents [67]. 

Villa, A., Campione, C., and Prati, L. Bimetallic gold/platinum catalyst for the selective liquid phase oxidation of glycerol. Catal Lett., 115, 133 (2007). 

In addition to this possibility, Lamy and co-workers [41] also proposed that glycerol can interact with platinum oxides, formed at high overpotentials, by simultaneous attack of two carbon atoms ... 

With a different approach, the influence of bismuth on the electrocatalysis of glycerol was also investigated by Koper and co-workers [67]. They observed that a carbon supported platinum electrode in a bismuth-saturated solution is highly selective to the electro-oxidation of the secondary alcohol of the glycerol, leading to 100 % of dihydroxyacetone at a carefully chosen potential. Using a combinatiOTi of online HPLC and in situ FTIR, the authors have shown that bismuth not only blocks the pathway towards the primary alcohol oxidation but also provides a... 

Kwon Y, Schouten KIP, Koper MTM (2011) Mechanism of the catalytic oxidation of glycerol on polycrystalline gold and platinum electrodes. ChemCatChem 3 1176-1185... 

Kahyaoglu A, Beden B, Lamy C (1984) The electrocatalytic oxidation of glycerol on gold and platinum-electrodes in aqueous-media. Electrochim Acta 29 1489-1492... 

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