Glycerol selective oxidation

Au/C was established to be a good candidate for selective oxidation carried out in liquid phase showing a higher resistance to poisoning with respect to classical Pd-or Pt-based catalysts [40]. The reaction pathway for glycerol oxidation (Scheme 1) is complicated as consecutive or parallel reactions could take place. Moreover, in the presence of a base interconversion between different products through keto-enolic equilibria could be possible. 

Table 3. Selective oxidation of glycerol using l%Au/C catalyst prepared via sol immobilisation.

The importance of size control has been depicted for the selective oxidation of glycerol it was shown that by increasing particle size a high selectivity to glycerate has been reached at the expense of the consecutive oxidation of glycerate to tartronate. 

Fig. 5 Scheme of the possible products obtained from glycerol by selective oxidation, with an indication also of other possible routes for upgrading glycerol. 

S. Carrettin, P. McMom, P. Johnston, K. Griffin, and G. J. Hutchings, Selective oxidation of glycerol to glyceric acid using a gold catalyst in aqueous sodium hydroxide, Chem. Commun. 7, 696-697 (2002). 

The selective oxidation of a 50% aqueous solution of glycerol was performed at 50 °C with an oxygen/glycerol ratio of 2, in a continuous fixed bed process using a Pt-Bi catalyst supported on charcoal. Here, a DHA selectivity of 80% at a conversion of 80% was obtained. 

Hutchings and coworkers demonstrated, that in the selective oxidation of glycerol the selectivity to glyceric acid was 100% at a conversion of 50% but gradually decreased to 86% at 72% conversion under 0.3 MPa of 02 at 333 K over Au/AC in the presence of an equimolar amount of NaOH [169, 179-181]. More than an equimolar amount of NaOH was necessary to promote the reaction the reaction did not occur without base. 

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. 

Porta F, Prati L. Selective oxidation of glycerol to sodium glycerate with gold-on-carbon catalyst an insight into reaction selectivity. J Catal. 2004 224 397-403. 

Figure 4. Oxidation of allyl alcohol in water at 65 °C conversion glycidol selectivity glycerol selectivity.

Figure 5. Oxidation of allyl alcohol in methanol at 65 C conversion glycidol selectivity A ether diols glycerol selectivity.

A large number of products can be obtained from glycerol oxidation processes (Scheme 3.7). If the secondary hydroxy group of glycerol is oxidized selectively, dihydroxyacetone (DHA) is formed. DHA has been used for years as an active... 

Glycerol can be oxidized to the high value-added products given in Figure 3. One of the two primary alcohol functions can be selectively oxidized in basic media to give sodium glycerate. This was best achieved with Pd/C catalyst at pH 11 [62] glycerate selectivity was 70% at 100% conversion, tartronate and oxalate were the main by-products. 

Single-phase bimetallic system for the selective oxidation of glycerol to glycerate... 

Au-Pd bimetallic systems on carbon, (Pd Au)/C (1) and Pd Au/C (2), have been prepared by using metallic colloidal solutions, following two different procedures. The total metal loading was l%wt and Au/Pd molar ratio 6/4. The catalytic activities have been studied and compared in the selective oxidation of glycerol to glycerate, in basic medium. 

Hirasawa S, Nakagawa Y, Tomishige K (2012) Selective oxidation of glycerol to dihydroxy-acetone over Pd-Ag catalyst. Catal Sci Technol 2 1150-1152... 

Hirasawa S, Watanabe H, Kizuka T, Nakagawa Y, Tomishige K (2013) Performance, structure and mechanism of Pd-Ag alloy catalyst for selective oxidation of glycerol to dihydroxyace-tone. J Catal 300 205-216... 

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